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English Platelet functional responses and signalling: the molecular relationship. Part 2: receptors.
Alexey Martyanov1,2,3
, Alexey Martyanov
MSU, Faculty of physics
Mikhail Panteleev1,2,4
show the whole list
Introduction
Platelets are blood cells that play a key role in the process of stopping bleeding
[
1
Hemostasis and thrombosis beyond biochemistry: roles of geometry, flow and diffusion
M. Panteleev, N. Dashkevich, F. Ataullakhanov
Thrombosis Research. 2015, 136, 699-711
]
, as well as in the formation of a hemostatic plug in trauma
[
2
Novel mouse hemostasis model for real-time determination of bleeding time and hemostatic plug composition
T. Getz, R. Piatt, B. Petrich, D. Monroe, N. Mackman, W. Bergmeier
Journal of Thrombosis and Haemostasis. 2015, 13, 417-425
]
, maintaining the integrity of blood vessels
[
3,
Platelets and vascular integrity
C. Deppermann
Platelets. 2018, 29, 549-555
4,
Physiological and pathophysiological aspects of blood platelet activation through CLEC-2 receptor
A. Martyanov, V. Kaneva, M. Panteleev, A. Sveshnikova
Oncohematology. 2018, 13, 83-90
5
How platelets safeguard vascular integrity
B. HO-TIN-NOÉ, M. DEMERS, D. WAGNER
Journal of Thrombosis and Haemostasis. 2011, 9, 56-65
]
and modulating immune responses
[
6,
Platelet ITAM signaling is critical for vascular integrity in inflammation
Yacine Boulaftali, Paul R. Hess, Todd M. Getz, Agnieszka Cholka, Moritz Stolla, Nigel Mackman, A. Phillip Owens III, Jerry Ware, Mark L. Kahn, Wolfgang Bergmeier
The Journal of Clinical Investigation. 2013, 123 (2), 908-916
7,
Editorial: Platelets and Immune Responses During Thromboinflammation
M. Schattner, C. Jenne, S. Negrotto, B. Ho-Tin-Noe
Frontiers in Immunology. 2020, 11, None
8
The dual role of platelet-innate immune cell interactions in thrombo-inflammation
J. Rayes, J. Bourne, A. Brill, S. Watson
Research and Practice in Thrombosis and Haemostasis. 2020, 4, 23-35
]
. The protein composition of platelets is predetermined, although minor de novo protein synthesis is still present
[
9
Lipopolysaccharide Signaling without a Nucleus: Kinase Cascades Stimulate Platelet Shedding of Proinflammatory IL-1β–Rich Microparticles
G. Brown, T. McIntyre
The Journal of Immunology. 2011, 186, 5489-5496
]
. However, the main functional responses of the platelet (Figure 1) are independent of protein synthesis
[
10
Platelet functional responses and signalling: the molecular relationship. Part 1: responses.
A. Sveshnikova, M. Stepanyan, M. Panteleev
Systems Biology and Physiology Reports. 2021, 1, 20-28
]
.
The first response to a meeting with an activator is a change in shape. Initially, discoid cells significantly increase their surface area due to the unraveling of the membrane folds inside in the form of an open canalicular system
[
11
Platelets: production, morphology and ultrastructure
Thon JN, Italiano JE
Handbook of Experimental Pharmacology. 2012, None, 3-22
]
. The shape change occurs in several stages
[
12
Platelet shape change and spreading
Aslan JE, Itakura A, Gertz JM, McCarty OJT
Methods in Molecular Biology. 2012, 788, 91-100
]
: microtubule depolymerization
[
13,
Tubulin in Platelets: When the Shape Matters
E. Cuenca-Zamora, F. Ferrer-Marín, J. Rivera, R. Teruel-Montoya
International Journal of Molecular Sciences. 2019, 20, 3484
14
New explanations for old observations: marginal band coiling during platelet activation
K. Sadoul
Journal of Thrombosis and Haemostasis. 2015, 13, 333-346
]
, rearrangement of the actin cytoskeleton
[
15
Actin dynamics in platelets
Bearer EL, Prakash JM, Li Z.
International Review of Cytology. 2002, 217, 137-82
]
and the sequential formation of the filopodia and lamellipodia
[
12
Platelet shape change and spreading
Aslan JE, Itakura A, Gertz JM, McCarty OJT
Methods in Molecular Biology. 2012, 788, 91-100
]
. Platelets can spread on the surface, and this process is majorly governed by the actin cytoskeleton
[
12,
Platelet shape change and spreading
Aslan JE, Itakura A, Gertz JM, McCarty OJT
Methods in Molecular Biology. 2012, 788, 91-100
16
Platelet Shape Changes and Cytoskeleton Dynamics as Novel Therapeutic Targets for Anti-Thrombotic Drugs
E. Shin, H. Park, J. Noh, K. Lim, J. Chung
Biomolecules & Therapeutics. 2017, 25, 223-230
]
.
The key functional response of the platelet, probably, is the transition to a proaggregant state, in which platelet integrins αIIbβ3
[
17
The first comprehensive and quantitative analysis of human platelet protein composition allows the comparative analysis of structural and functional pathways
J. Burkhart, M. Vaudel, S. Gambaryan, S. Radau, U. Walter, L. Martens, J. Geiger, A. Sickmann, R. Zahedi
Blood. 2012, 120, e73-e82
]
pass into a state with high affinity for fibrinogen
[
18
Platelet signaling
Stalker TJ, Newman DK, Ma P, Wannemacher KM, Brass LF
Handbook of Experimental Pharmacology. 2012, None, 59-85
]
and provide platelet “adhesion” through the “αIIbβ3 - fibrinogen - αIIbβ3 bridges”
[
19
Regulation of Platelet Activation and Coagulation and Its Role in Vascular Injury and Arterial Thrombosis
M. Tomaiuolo, L. Brass, T. Stalker
Interventional Cardiology Clinics. 2017, 6, 1-12
]
. Thus, the path from receptors to the activation of integrins is called “inside-out”, while the enhancement of platelet activation, in which integrins already act as receptors, is called “outside-in”
[
20
RAP GTPases and platelet integrin signaling
L. Stefanini, W. Bergmeier
Platelets. 2019, 30, 41-47
]
.
Another important functional response of the platelet is granule release
[
10
Platelet functional responses and signalling: the molecular relationship. Part 1: responses.
A. Sveshnikova, M. Stepanyan, M. Panteleev
Systems Biology and Physiology Reports. 2021, 1, 20-28
]
. Platelets contain three types of granules: α- and δ-granules and lysosomes, and it is believed that the release of alpha-granules occurs at weaker stimulation. In contrast, the release of dense granules is a sign of strong platelet activation
[
21
Platelet Secretion. In: Michelson AD, editor. Platelets (Fourth Edition)
Flaumenhaft R, Sharda A
Academic Press. 2019, None, 349-70
]
. a-granules contain various proteins, glycoproteins, and chemokines, while dense (δ) granules contain primarily low-molecular substances and ions
[
22
Sorting machineries: how platelet-dense granules differ from α-granules
Y. Chen, Y. Yuan, W. Li
Bioscience Reports. 2018, 38, None
]
. All substances secreted by platelets play an essential role in the secondary activation of platelets and the regulation of the lumen of the vessel and the immune response
[
10
Platelet functional responses and signalling: the molecular relationship. Part 1: responses.
A. Sveshnikova, M. Stepanyan, M. Panteleev
Systems Biology and Physiology Reports. 2021, 1, 20-28
]
.
Under certain conditions, for example, upon stimulation of platelets with the combination of thrombin and collagen, mitochondrial-dependent necrosis of a subpopulation of platelets occurs, which at the same time lose the capability to aggregate, exhibit a negatively charged phospholipid phosphatidylserine, which is one of the landing sites for tenase and prothrombinase complexes, which significantly accelerates the work of the blood plasma coagulation cascade
[
23,
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
24
Procoagulant Platelets Form an α-Granule Protein-covered “Cap” on Their Surface That Promotes Their Attachment to Aggregates
A. Abaeva, M. Canault, Y. Kotova, S. Obydennyy, A. Yakimenko, N. Podoplelova, V. Kolyadko, H. Chambost, A. Mazurov, F. Ataullakhanov, A. Nurden, M. Alessi, M. Panteleev
Journal of Biological Chemistry. 2013, 288, 29621-29632
]
. This population is called "procoagulant". It is assumed that many procoagulant platelets in the thrombus nucleus promote the acceleration of fibrin polymerization, which strengthens the thrombus
[
25,
Regulating thrombus growth and stability to achieve an optimal response to injury
L. BRASS, K. WANNEMACHER, P. MA, T. STALKER
Journal of Thrombosis and Haemostasis. 2011, 9, 66-75
26
Clot Contraction Drives the Translocation of Procoagulant Platelets to Thrombus Surface
D. Nechipurenko, N. Receveur, A. Yakimenko, T. Shepelyuk, A. Yakusheva, R. Kerimov, S. Obydennyy, A. Eckly, C. Léon, C. Gachet, E. Grishchuk, F. Ataullakhanov, P. Mangin, M. Panteleev
Arteriosclerosis, Thrombosis, and Vascular Biology. 2019, 39, 37-47
]
. Transitions of the platelets between different states with different degrees of activation are shown in Figure 1.
Figure 1. Different degrees of the platelet activation in hemostasis. Upon weak stimulation, platelets pass into a weakly activated state, in which there is no clustering of platelet integrins and no significant change in the shape of platelets. This weak activation is reversible, and it corresponds to the state of platelets in the outer layers ("coat") of the thrombus. Upon stronger activation, platelet shape significantly changes. Platelets become irreversibly activated and aggregate. The secretion of platelet granules also occurs. At the maximum degree of activation, platelet mitochondria collapse, and platelets pass into a procoagulant state, exposing phosphatidylserine, which significantly accelerates blood plasma coagulation.
A vast network of receptors and signaling pathways of platelets regulates implementing the listed functions where and when required
[
10
Platelet functional responses and signalling: the molecular relationship. Part 1: responses.
A. Sveshnikova, M. Stepanyan, M. Panteleev
Systems Biology and Physiology Reports. 2021, 1, 20-28
]
. How does it work? It turns out that the basic principles of information transfer are applicable to living cells. Namely, the system must have a "source", "transmitter," and "receiver" (Fig. 2). From the point of view of the platelet, the external signal is processed by receptors, which transmit signals to the inside of the cell to the transmitters – secondary messengers. This review will focus on analyzing how various platelet activators regulate the concentrations of secondary messengers, which, in turn, control the listed functional responses, which will be discussed in the third part of this series.
Figure 2. The basic scheme of signal transduction by a non-nucleated cell. From the extracellular environment comes some "signal" that activates the receptor. This leads to secondary messengers, which, passing through the "amplification", induce intermediate and then functional responses. The system also contains regulators that play the role of positive or negative feedback loops.
Secondary messengers of the platelets
The platelet receptor network can be roughly divided into several sub-networks, each controlled by its own set of secondary messengers, which may overlap in some cases. It can be argued that secondary messengers are at the center of intracellular signaling: they “collect” information from receptors and “transmit” it to functional systems. Therefore, in this review, we will look at how the concentration of the secondary messengers in the platelets is regulated. In this case, one should not forget that platelets are non-nucleated cells, i.e., they have no pathways that induce protein synthesis. Below, we briefly list the primary, secondary platelet messengers.
Based on the previously published works
[
27,
Platelet biology and functions: new concepts and clinical perspectives
P. van der Meijden, J. Heemskerk
Nature Reviews Cardiology. 2019, 16, 166-179
28,
Computational biology analysis of platelet signaling reveals roles of feedbacks through phospholipase C and inositol 1,4,5-trisphosphate 3-kinase in controlling amplitude and duration of calcium oscillations
F. Balabin, A. Sveshnikova
Mathematical Biosciences. 2016, 276, 67-74
29
Dynamics of calcium spiking, mitochondrial collapse and phosphatidylserine exposure in platelet subpopulations during activation
S. Obydennyy, A. Sveshnikova, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 1867-1881
]
, which aligns with our vision, the critical secondary messenger in the platelet is the cytosolic free calcium ions. Under resting conditions, its low levels are maintained by membrane ATPases PMCA and SERCA (sarcoplasmic/endoplasmic reticulum calcium ATPase)
[
23,
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
30
Control of Platelet CLEC-2-Mediated Activation by Receptor Clustering and Tyrosine Kinase Signaling
A. Martyanov, F. Balabin, J. Dunster, M. Panteleev, J. Gibbins, A. Sveshnikova
Biophysical Journal. 2020, 118, 2641-2655
]
, which “pump out” calcium from the cytosol to the extracellular space or to intracellular stores, respectively
[
23,
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
29
Dynamics of calcium spiking, mitochondrial collapse and phosphatidylserine exposure in platelet subpopulations during activation
S. Obydennyy, A. Sveshnikova, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 1867-1881
]
. Calcium mobilization (i.e., release) can occur via varied membrane channels
[
23
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
]
. Usually, inositol-1,4,5-triphosphate (inositol-1,4,5-triphosphate, IP3), which is generated by the phospholipase C on the plasma membrane, activates receptor channels to IP3 (IP3R)
[
31,
Compartmentalized calcium signaling triggers subpopulation formation upon platelet activation through PAR1
A. Sveshnikova, F. Ataullakhanov, M. Panteleev
Molecular BioSystems. 2015, 11, 1052-1060
32
Calcium signaling in platelets
D. VARGA-SZABO, A. BRAUN, B. NIESWANDT
Journal of Thrombosis and Haemostasis. 2009, 7, 1057-1066
]
. Based on the studies of calcium signaling in single cells, an increase in calcium concentration during platelet activation does not occur uniformly but in the form of individual spikes
[
27,
Platelet biology and functions: new concepts and clinical perspectives
P. van der Meijden, J. Heemskerk
Nature Reviews Cardiology. 2019, 16, 166-179
29
Dynamics of calcium spiking, mitochondrial collapse and phosphatidylserine exposure in platelet subpopulations during activation
S. Obydennyy, A. Sveshnikova, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 1867-1881
]
, which merge, possibly due to IP3R clustering
[
33
Agonist-evoked inositol trisphosphate receptor (IP3R) clustering is not dependent on changes in the structure of the endoplasmic reticulum
M. Chalmers, M. Schell, P. Thorn
Biochemical Journal. 2006, 394, 57-66
]
.
While the primary storage for calcium ions in platelets is the endoplasmic reticulum, calcium adhesions can also pump calcium into platelet mitochondria through a calcium uniporter. Calcium can also be pumped out of mitochondria through the NCLX pump
[
23
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
]
. However, strong activation, mitochondrial overload with calcium, a drop in mitochondrial potential, opening the mitochondrial pore, and mitochondrial collapse can occur. All this leads to necrosis and the transition of the platelets to the procoagulant state
[
23
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
]
. For example, it has been shown that if there are fewer mitochondria in platelets, then they become more prone to become procoagulant
[
34
Mechanisms of increased mitochondria-dependent necrosis in Wiskott-Aldrich syndrome platelets
S. Obydennyi, E. Artemenko, A. Sveshnikova, A. Ignatova, T. Varlamova, S. Gambaryan, G. Lomakina, N. Ugarova, I. Kireev, F. Ataullakhanov, G. Novichkova, A. Maschan, A. Shcherbina, M. Panteleev
Haematologica. 2020, 105, 1095-1106
]
. There are also hypotheses about the initial pre-determinism of a part of platelets to the transition to a procoagulant state, which may also be related to the number of their mitochondria
[
35
Platelet subpopulations remain despite strong dual agonist stimulation and can be characterised using a novel six-colour flow cytometry protocol
A. Södergren, S. Ramström
Scientific Reports. 2018, 8, None
]
. Procoagulant platelets can be formed not only by the pathway of necrosis but also by the classical pathway of mitochondria-dependent apoptosis, induced, for example, by inhibitors of Bcl-proteins (e.g., ABT-737)
[
36
Программируемая клеточная смерть и функциональная активность тромбоцитов при онкогематологических заболеваниях
А. Мартьянов, А. Игнатова, Г. Свидельская, Е. Пономаренко, С. Гамбарян, А. Свешникова, М. Пантелеев
Биохимия. 2020, 85, 1489-1499
]
.
IP3 is also a secondary messenger, as it is formed due to phospholipase C activity combined with diacylglycerol (DAG) from a membrane phospholipid phosphoinositide-4,5-bisphosphate (PIP2). Interestingly, the concentration of IP3 in the platelet cytosol also depends on the enzyme IP3-3 kinase (IP3K)
[
37
Expression, Purification, and Regulation of Two Isoforms of the Inositol 1,4,5-Trisphosphate 3-Kinase
P. Woodring, J. Garrison
Journal of Biological Chemistry. 1997, 272, 30447-30454
]
. IP3K catalyzes the phosphorylation of IP3, thereby directly reducing the number of secondary messengers available to interact with IP3R. According to
[
38
Glutamate regulation of calcium and IP3 oscillating and pulsating dynamics in astrocytes
M. De Pittà, M. Goldberg, V. Volman, H. Berry, E. Ben-Jacob
Journal of Biological Physics. 2009, 35, 383-411
]
, IP3K is activated by high concentrations of calcium-bound calmodulin, which are available only at high concentrations of cytosolic calcium (> 1 μM). It is assumed that upon platelet activation, IP3 concentration reaches 1-2 μM (this concentration is enough to open IP3R completely
[
23,
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
28
Computational biology analysis of platelet signaling reveals roles of feedbacks through phospholipase C and inositol 1,4,5-trisphosphate 3-kinase in controlling amplitude and duration of calcium oscillations
F. Balabin, A. Sveshnikova
Mathematical Biosciences. 2016, 276, 67-74
]
), but it should be noted that experimental data on the absolute concentration of inositol-1,4,5-triphosphate in platelets are absent (despite the fact that this is the most active form of IP3, other forms are also observed in intracellular signaling, primarily inositol-1,3,4-triphosphate, the concentration of which can be much higher, and experimental separation of these substances is difficult)
[
39
Inositol 1,4,5-trisphosphate 3-kinases: functions and regulations
H. XIA, G. YANG
Cell Research. 2005, 15, 83-91
]
.
A secondary messenger comparable in importance to calcium is the membrane concentration of the phospholipid phosphoinositide-3,4,5-triphosphate (phosphoinositide-3,4,5-trisphosphate, PIP3). Phosphorylated residues of inositide — phosphoinositides — account for 10–15% of the lipid composition of the inner layer of the plasma membrane of platelets
[
40
Regulation of platelet plug formation by phosphoinositide metabolism
S. Min, C. Abrams
Blood. 2013, 122, 1358-1365
]
. Among membrane phosphoinositides, the most abundant is PIP2, which is synthesized from phosphoinositide-4-phosphate by phosphatidylinositide-4-phosphate-5-kinase (PI4.5K)
[
40
Regulation of platelet plug formation by phosphoinositide metabolism
S. Min, C. Abrams
Blood. 2013, 122, 1358-1365
]
. PIP2 can independently act as a docking site for proteins associated with membranes: PIP2 is a docking site for talin, a key protein required for the association of platelet integrins and the actin cytoskeleton
[
41,
Platelet Signal Transduction. In: Michelson AD, editor. Platelets (Fourth Edition)
Lee RH, Stefanini L, Bergmeier W.
Academic Press. 2019, None, 329-48
42
Recruitment and regulation of phosphatidylinositol phosphate kinase type 1γ by the FERM domain of talin
G. Di Paolo, L. Pellegrini, K. Letinic, G. Cestra, R. Zoncu, S. Voronov, S. Chang, J. Guo, M. Wenk, P. De Camilli
Nature. 2002, 420, 85-89
]
. Studies in mice deficient in specific isoforms of PIP5K indicate that several distinct pools of PIP2 exist within the platelet membrane; PIP2, produced by PIP5Kγ, is important for membrane attachment to the underlying cytoskeleton, while PIP2, synthesized by PIP5Kα and PIP5Kβ, is used as a substrate for secondary messengers
[
43
Platelets lacking PIP5KIγ have normal integrin activation but impaired cytoskeletal-membrane integrity and adhesion
Y. Wang, L. Zhao, A. Suzuki, L. Lian, S. Min, Z. Wang, R. Litvinov, T. Stalker, T. Yago, A. Klopocki, D. Schmidtke, H. Yin, J. Choi, R. McEver, J. Weisel, J. Hartwig, C. Abrams
Blood. 2013, 121, 2743-2752
]
. PIP2 is a substrate for the two key signaling enzymes, PLC and PI3K, which will be discussed below. Phosphoinositide-3-kinase (PI3K) phosphorylates various phosphoinositides at the 3rd carbon atom. PIP3 is the most important of its products
[
44
The role of class I, II and III PI 3-kinases in platelet production and activation and their implication in thrombosis
C. Valet, S. Severin, G. Chicanne, P. Laurent, F. Gaits-Iacovoni, M. Gratacap, B. Payrastre
Advances in Biological Regulation. 2016, 61, 33-41
]
. PIP3, alike PIP2, is recognized by specific PH-domains of proteins. It is also recognized by the PX and FYVE domains. Phosphoinositide signaling is associated with membrane docking and subsequent activation of proteins containing PH domains, such as PLCγ2, Btk / Tec, and serine / threonine kinase Akt
[
44
The role of class I, II and III PI 3-kinases in platelet production and activation and their implication in thrombosis
C. Valet, S. Severin, G. Chicanne, P. Laurent, F. Gaits-Iacovoni, M. Gratacap, B. Payrastre
Advances in Biological Regulation. 2016, 61, 33-41
]
. Akt phosphorylation is the key effector of PI3K-dependent PIP3 generation in platelets. It is noteworthy that Kindlin 3, a component of the platelet integrin activation complex that controls the avidity of integrins to fibrinogen, has an atypical FERM domain that also contains a PH domain
[
46
Structure and lipid-binding properties of the kindlin-3 pleckstrin homology domain
T. Ni, A. Kalli, F. Naughton, L. Yates, O. Naneh, M. Kozorog, G. Anderluh, M. Sansom, R. Gilbert
Biochemical Journal. 2017, 474, 539-556
]
. PIP3 clusters can be considered as the governing centers for signal propagation
[
41
Platelet Signal Transduction. In: Michelson AD, editor. Platelets (Fourth Edition)
Lee RH, Stefanini L, Bergmeier W.
Academic Press. 2019, None, 329-48
]
. On the other hand, phosphoinositide signaling in platelets is regulated by lipid phosphatases (PTEN, SHIP1, SHIP2), which, by decreasing the PIP3 level, suppresses PI3K-dependent platelet activation
[
17,
The first comprehensive and quantitative analysis of human platelet protein composition allows the comparative analysis of structural and functional pathways
J. Burkhart, M. Vaudel, S. Gambaryan, S. Radau, U. Walter, L. Martens, J. Geiger, A. Sickmann, R. Zahedi
Blood. 2012, 120, e73-e82
47
Different roles of SHIP1 according to the cell context: The example of blood platelets
M. Gratacap, S. Séverin, G. Chicanne, M. Plantavid, B. Payrastre
Advances in Enzyme Regulation. 2008, 48, 240-252
]
. In particular, for mice, SHIP1 plays a major role in the downregulation of PIP3 concentrations
[
48
SH2-containing inositol 5-phosphatases 1 and 2 in blood platelets: their interactions and roles in the control of phosphatidylinositol 3,4,5-trisphosphate levels
S. GIURIATO, X. PESESSE, S. BODIN, T. SASAKI, C. VIALA, E. MARION, J. PENNINGER, S. SCHURMANS, C. ERNEUX, B. PAYRASTRE
Biochemical Journal. 2003, 376, 199-207
]
, however, its deficiency does not affect the “inside-out” activation of integrins
[
49
Deficiency of Src homology 2 domain–containing inositol 5-phosphatase 1 affects platelet responses and thrombus growth
S. Séverin, M. Gratacap, N. Lenain, L. Alvarez, E. Hollande, J. Penninger, C. Gachet, M. Plantavid, B. Payrastre
Journal of Clinical Investigation. 2007, 117, 944-952
]
.
The last secondary mediator of platelet signaling is the cytosolic concentration of cyclic nucleotides - cAMP and cGMP
[
50
Effects of bacterial lipopolysaccharides on platelet function: inhibition of weak platelet activation
A. Martyanov, A. Maiorov, A. Filkova, A. Ryabykh, G. Svidelskaya, E. Artemenko, S. Gambaryan, M. Panteleev, A. Sveshnikova
Scientific Reports. 2020, 10, None
]
. Cyclic nucleotides are generated by cyclases: adenylate cyclase (cAMP from ATP) and guanylate cyclase (cGMP from GTP) and are converted into monophosphoribonucleotides by low-specific phosphodiesterases (PDE)
[
51
GMP and cGMP-dependent protein kinase in platelets and blood cells
Walter U, Gambaryan S
Handbook of Experimental Pharmacology. 2009, None, 533-48
]
. While PDE activity is mainly regulated by the availability of substrates, cyclase activity can be either increased or decreased by external signals. Thus, the concentration of cyclic nucleotides in platelets can change in both directions
[
51,
GMP and cGMP-dependent protein kinase in platelets and blood cells
Walter U, Gambaryan S
Handbook of Experimental Pharmacology. 2009, None, 533-48
52
A review and discussion of platelet nitric oxide and nitric oxide synthase: do blood platelets produce nitric oxide from l-arginine or nitrite?
S. Gambaryan, D. Tsikas
Amino Acids. 2015, 47, 1779-1793
]
. An increase in the amount of cAMP in the cell leads to the activation of cAMP-dependent protein kinase A (PKA)
[
53
A Boolean view separates platelet activatory and inhibitory signalling as verified by phosphorylation monitoring including threshold behaviour and integrin modulation
M. Mischnik, D. Boyanova, K. Hubertus, J. Geiger, N. Philippi, M. Dittrich, G. Wangorsch, J. Timmer, T. Dandekar
Molecular BioSystems. 2013, 9, 1326
]
. Activate PKA phosphorylates many regulatory proteins such as VASP (vasodilator-stimulated phosphoprotein). In addition, PKA indirectly regulates calcium signaling by phosphorylating IP3R and PMCA
[
50
Effects of bacterial lipopolysaccharides on platelet function: inhibition of weak platelet activation
A. Martyanov, A. Maiorov, A. Filkova, A. Ryabykh, G. Svidelskaya, E. Artemenko, S. Gambaryan, M. Panteleev, A. Sveshnikova
Scientific Reports. 2020, 10, None
]
. It is known that an increase in the level of cAMP suppresses all functional responses of platelets; however, the mechanisms of this suppression have been studied superficially. Perhaps phospho-proteomics of platelets in response to forskolin (an activator of AS) will give answers here
[
17
The first comprehensive and quantitative analysis of human platelet protein composition allows the comparative analysis of structural and functional pathways
J. Burkhart, M. Vaudel, S. Gambaryan, S. Radau, U. Walter, L. Martens, J. Geiger, A. Sickmann, R. Zahedi
Blood. 2012, 120, e73-e82
]
.
G-protein coupled receptors (GPCRs)
Approximately half of the platelet receptors are serpentine receptors, otherwise called 7TM receptors or G-protein coupled receptors (GPCR)
[
54
Activation of Platelet Function Through G Protein–Coupled Receptors
S. Offermanns
Circulation Research. 2006, 99, 1293-1304
]
. GPCRs are one of the largest protein families in humans. GPCRs recognize a wide variety of extracellular signals and control a variety of cellular and physiological responses
[
55
Kinetic diversity in G-protein-coupled receptor signalling
V. Katanaev, M. Chornomorets
Biochemical Journal. 2007, 401, 485-495
]
. GPCRs transmit signals into the cell by activating trimeric G-proteins. These proteins at rest exist as heterotrimers of α, β, and γ subunits, where the α subunit is associated with GDP. The GαGDPβγ complex can associate with GPCR. When bound to an extracellular ligand, GPCR is activated and functions as a GEF (Guanine-nucleotide Exchange Factor) for G-proteins, catalyzing the exchange of α-subunit-associated GDP for GTP. This leads to the dissociation of the complex into activated GPCR, GαGTP, and βγ, which can independently transmit signals to various downstream effectors. Over time, GTP to Gα is hydrolyzed back to GDP via the intrinsic GTPase activity of Gα or via GAP (GTPase-activating protein). GAP-like activity is exhibited by direct targets of GαGTP, for example, PLCβ (phospholipase Cβ), or specialized proteins of the RGS family (Regulator of G-protein Signaling)
[
56
Synergistic Activation of Phospholipase C-β3 by Gαq and Gβγ Describes a Simple Two-State Coincidence Detector
F. Philip, G. Kadamur, R. Silos, J. Woodson, E. Ross
Current Biology. 2010, 20, 1327-1335
]
. GαGDP can bind βγ and restore the original complex. It is believed that receptor activation leads to a significant increase in steady-state concentrations of free GαGTP and βγ and a corresponding intracellular signal. After some time, activation decreases as a result of the disappearance of the ligand
[
57
A quantitative characterization of the yeast heterotrimeric G protein cycle
T. Yi, H. Kitano, M. Simon
Proceedings of the National Academy of Sciences. 2003, 100, 10764-10769
]
or removal of the receptor from the cell surface (desensitization due to internalization)
[
58
Receptor-Mediated Activation of Heterotrimeric G-Proteins in Living Cells
C. Janetopoulos
Science. 2001, 291, 2408-2411
]
. Under certain conditions, covalent unlinking of the receptor with G-proteins occurs. The homogeneity of G-protein activation by GPCR raises the problem of specificity in the GPCR signal, considered in the works of V.L. Katanaev et al.
[
55,
Kinetic diversity in G-protein-coupled receptor signalling
V. Katanaev, M. Chornomorets
Biochemical Journal. 2007, 401, 485-495
59,
A Direct and Functional Interaction Between Go and Rab5 During G Protein-Coupled Receptor Signaling
V. Purvanov, A. Koval, V. Katanaev
Science Signaling. 2010, 3, ra65-ra65
60,
Double Suppression of the Gα Protein Activity by RGS Proteins
C. Lin, A. Koval, S. Tishchenko, A. Gabdulkhakov, U. Tin, G. Solis, V. Katanaev
Molecular Cell. 2014, 53, 663-671
]
. Moreover, receptors can activate G proteins containing different Gα subunits
[
63
Biochemical and pharmacological control of the multiplicity of coupling at G-protein-coupled receptors
E. Hermans
Pharmacology & Therapeutics. 2003, 99, 25-44
]
. There are multiple enzymes activated by G-proteins or simply localized by G-proteins at the membrane; we will consider only the most important ones for platelet activation.
Due to the importance of calcium signaling, we start with phospholipase Cβ (phospholipase C, PLCβ), which hydrolyzes PIP2 to inositol 3,4,5 triphosphate (IP3) and diacylglycerol (DAG). PLCβ activation consists in its localization at the plasma membrane close to its substrates
[
64,
Bifurcation of Lipid and Protein Kinase Signals of PI3K to the Protein Kinases PKB and MAPK
T. Bondeva
Science. 1998, 282, 293-296
65
Synergistic Activation of Phospholipase C-β3 by Gαq and Gβγ Describes a Simple Two-State Coincidence Detector
F. Philip, G. Kadamur, R. Silos, J. Woodson, E. Ross
Current Biology. 2010, 20, 1327-1335
]
. It can be speculated that the longer the PLC stays near the membrane, the higher its activity. The key factor keeping PLCβ near the membrane is type q GαGTP
[
23
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
]
. However, Gβγ is also able to retain PLCβ (especially type 3 PLCβ) near the membrane independently from Ga, and together with the α-subunit, the amplification of attraction can be more than 6-10 times
[
56
Synergistic Activation of Phospholipase C-β3 by Gαq and Gβγ Describes a Simple Two-State Coincidence Detector
F. Philip, G. Kadamur, R. Silos, J. Woodson, E. Ross
Current Biology. 2010, 20, 1327-1335
]
. Moreover, activation by intracellular calcium concentration is also of essential importance for PLC
[
66,
The actin-binding protein profilin binds to PIP2 and inhibits its hydrolysis by phospholipase C
P. Goldschmidt-Clermont, L. Machesky, J. Baldassare, T. Pollard
Science. 1990, 247, 1575-1578
67
Structure, Function, and Control of Phosphoinositide-Specific Phospholipase C
M. Rebecchi, S. Pentyala
Physiological Reviews. 2000, 80, 1291-1335
]
. According to
[
67
Structure, Function, and Control of Phosphoinositide-Specific Phospholipase C
M. Rebecchi, S. Pentyala
Physiological Reviews. 2000, 80, 1291-1335
]
, PLC has several Ca2+ -binding sites, but only one of them is catalytic
[
68
Catalysis by Phospholipase C δ1 Requires That Ca2+ Bind to the Catalytic Domain, but Not the C2 Domain
J. Grobler, J. Hurley
Biochemistry. 1998, 37, 5020-5028
]
. According to
[
69
Activation of phospholipase C-beta 2 mutants by G protein alpha q and beta gamma subunits
Lee SB, Shin SH, Hepler JR, Gilman AG, Rhee SG.
Journal of Biological Chemistry. 1993, 268, 25952–7
]
, the mutant type PLC, in which all calcium-binding sites are absent, except for the TIM catalytic cylinder, has kinetics similar to the wild type, which is described by the Hill equation with positive cooperativity. According to proteomics data
[
70
The first comprehensive and quantitative analysis of human platelet protein composition allows the comparative analysis of structural and functional pathways
J. Burkhart, M. Vaudel, S. Gambaryan, S. Radau, U. Walter, L. Martens, J. Geiger, A. Sickmann, R. Zahedi
Blood. 2012, 120, e73-e82
]
, there are about 2000 molecules of PLCβ2 and PLCβ3 in a platelet, which can create a sharp increase in the IP3 concentration in the cytosol with the rate of 200-400 s-1. The second product of PLC operation is diacylglycerol (DAG)
[
45
Impact of the PI3-kinase/Akt pathway on ITAM and hemITAM receptors: Haemostasis, platelet activation and antithrombotic therapy
A. Moroi, S. Watson
Biochemical Pharmacology. 2015, 94, 186-194
]
, which remains in the membrane and becomes an important docking site for many enzymes containing the C1 domain
[
71
Protein Kinase C in Oncogenic Transformation and Cell Polarity. In: Kramer IjM, editor. Signal Transduction (Third Edition)
Kramer IjM.
Boston: Academic Press. 2016, None, 529–88
]
. The most important DAG-activated enzymes are type C serine/threonine kinases (PKC), various isoforms of which are activated by binding to DAG and, sometimes, calcium, which leads to activation, degranulation, and changes in the shape of platelets
[
71
Protein Kinase C in Oncogenic Transformation and Cell Polarity. In: Kramer IjM, editor. Signal Transduction (Third Edition)
Kramer IjM.
Boston: Academic Press. 2016, None, 529–88
]
. Human platelets also express several diacylglycerol kinases (DGKs) responsible for the phosphorylation of DAG. Inhibition of DGK is known to attenuate platelet calcium responses to activation, which highlights the importance of DAG for intracellular signaling in platelets
[
72
Purification and characterization of cytosolic diacylglycerol kinases of human platelets.
Y. Yada, T. Ozeki, H. Kanoh, Y. Nozawa
Journal of Biological Chemistry. 1990, 265, 19237-19243
]
.
The second enzyme activated by G proteins is called phosphoinositide 3 kinase γ (PI3Kγ). The most characterized members of the PI3K family are PI3K class I, which are heterodimeric proteins: they consist of a catalytic subunit (p110α, p110β or p110δ) linked to an SH2-containing regulatory subunit (five types, with p85α being the most common). p110β associates with the plasma membrane via the Gβγ subunits. PI3K class IB (PI3Kγ) consists of the p110γ catalytic subunit associated with the regulatory subunit (p84), which is also activated by binding to the Gβγ subunit
[
73
Heterodimeric Phosphoinositide 3-Kinase Consisting of p85 and p110β Is Synergistically Activated by the βγ Subunits of G Proteins and Phosphotyrosyl Peptide
H. Kurosu, T. Maehama, T. Okada, T. Yamamoto, S. Hoshino, Y. Fukui, M. Ui, O. Hazeki, T. Katada
Journal of Biological Chemistry. 1997, 272, 24252-24256
]
. The most important for platelet is PI3K activation from P2Y12
[
20,
RAP GTPases and platelet integrin signaling
L. Stefanini, W. Bergmeier
Platelets. 2019, 30, 41-47
41
Platelet Signal Transduction. In: Michelson AD, editor. Platelets (Fourth Edition)
Lee RH, Stefanini L, Bergmeier W.
Academic Press. 2019, None, 329-48
]
, since its activation results in the release of the largest number of Gβγ subunits.
G12/13 - activates RhoA (GTPases Ras homolog gene family, member A) and Rho kinases. Activated Rho-kinase stimulates the phosphorylation of myosin light chains MLC (Myosin Light Chain)
[
74
Dichotomous regulation of myosin phosphorylation and shape change by Rho-kinase and calcium in intact human platelets
M Bauer, M Retzer, J I Wilde, P Maschberger, M Essler, M Aepfelbacher, S P Watson, W Siess
Blood. 1999, None, 1665–72
]
, thus participating in the platelet shape change and cytoskeleton rearrangement. Furthermore, RhoA is directly involved in granule secretion
[
18
Platelet signaling
Stalker TJ, Newman DK, Ma P, Wannemacher KM, Brass LF
Handbook of Experimental Pharmacology. 2012, None, 59-85
]
.
The last protein controlled by the platelet G-proteins, paradoxically, is adenylate cyclase (AC)
[
75,
Platelet Adenylyl Cyclase Activity: A Biological Marker for Major Depression and Recent Drug Use
L. Hines, B. Tabakoff
Biological Psychiatry. 2005, 58, 955-962
76
G-Protein–Coupled Receptors Signaling Pathways in New Antiplatelet Drug Development
P. Gurbel, A. Kuliopulos, U. Tantry
Arteriosclerosis, Thrombosis, and Vascular Biology. 2015, 35, 500-512
]
. The paradox here is related to the fact that AC controls the concentration of cAMP and, for many cells, for example, for myocytes, is the main enzyme in the regulation of energy metabolism. Since platelets live only a few days, the significance of glycogen stores and glycolysis / oxidative phosphorylation activity in platelets is questionable
[
77
Fueling Platelets
S. Whiteheart
Arteriosclerosis, Thrombosis, and Vascular Biology. 2017, 37, 1592-1594
]
. As has been mentioned earlier, the key role of AC in platelets is to control the concentration of cAMP. The dominating type of AC in platelets is AC3, a membrane enzyme that is activated upon binding to the Gs αGTP subunit and which is inhibited upon binding to the Gi or Gz αGTP subunit
[
78
Signaling through Gi Family Members in Platelets
J. Yang, J. Wu, H. Jiang, R. Mortensen, S. Austin, D. Manning, D. Woulfe, L. Brass
Journal of Biological Chemistry. 2002, 277, 46035-46042
]
.
One of the interesting features of GPCR receptors is the possibility of their desensitization as a result of contact with an activator
[
79,
G-Protein Coupled Receptor Resensitization - Appreciating the Balancing Act of Receptor Function
M. L. Mohan, N. T. Vasudevan, M. K. Gupta, E. E. Martelli, S. V. Naga Prasad
Current Molecular Pharmacology. 2013, 5, 350-361
80
Heterogeneity of Integrin αIIbβ3 Function in Pediatric Immune Thrombocytopenia Revealed by Continuous Flow Cytometry Analysis
A. Martyanov, D. Morozova, M. Sorokina, A. Filkova, D. Fedorova, S. Uzueva, E. Suntsova, G. Novichkova, P. Zharkov, M. Panteleev, A. Sveshnikova
International Journal of Molecular Sciences. 2020, 21, 3035
]
. It is believed that desensitization is necessary for cells to regulate their responses to tonic signals, which can lead to pathological hyperactivation and death
[
79
G-Protein Coupled Receptor Resensitization - Appreciating the Balancing Act of Receptor Function
M. L. Mohan, N. T. Vasudevan, M. K. Gupta, E. E. Martelli, S. V. Naga Prasad
Current Molecular Pharmacology. 2013, 5, 350-361
]
. Upon activation of the GPCR receptor and dissociation of Ga from Gbg, the GPCR itself can be phosphorylated by G-protein associated kinases (GRK). This leads to the landing on the GPCR of-arrestin and clathrin. PI3K also plays an important role in the desensitization process, as well as β-arrestin binds to phosphorylated GRK GPCRs, activate and produce PIP3, which is necessary for recruiting the AP-2 adapter protein. AP-2, clathrin, and β-arrestin trigger endocytosis of the GPCR receptor
[
79
G-Protein Coupled Receptor Resensitization - Appreciating the Balancing Act of Receptor Function
M. L. Mohan, N. T. Vasudevan, M. K. Gupta, E. E. Martelli, S. V. Naga Prasad
Current Molecular Pharmacology. 2013, 5, 350-361
]
. Thus, the receptor is inaccessible for both the agonist and the G-proteins. Desensitization of GPCR is reversible: upon internalization, dissociation of AP-2 and clathrin occurs, which decreases the affinity of β-arrestin for phosphorylated GPCR molecules
[
79
G-Protein Coupled Receptor Resensitization - Appreciating the Balancing Act of Receptor Function
M. L. Mohan, N. T. Vasudevan, M. K. Gupta, E. E. Martelli, S. V. Naga Prasad
Current Molecular Pharmacology. 2013, 5, 350-361
]
. This allows non-specific phosphatases (such as PP2) to dephosphorylate the GPCR. Dephosphorylated GPCRs return to the platelet plasma membrane and can again form complexes with G-proteins
[
79,
G-Protein Coupled Receptor Resensitization - Appreciating the Balancing Act of Receptor Function
M. L. Mohan, N. T. Vasudevan, M. K. Gupta, E. E. Martelli, S. V. Naga Prasad
Current Molecular Pharmacology. 2013, 5, 350-361
80
Heterogeneity of Integrin αIIbβ3 Function in Pediatric Immune Thrombocytopenia Revealed by Continuous Flow Cytometry Analysis
A. Martyanov, D. Morozova, M. Sorokina, A. Filkova, D. Fedorova, S. Uzueva, E. Suntsova, G. Novichkova, P. Zharkov, M. Panteleev, A. Sveshnikova
International Journal of Molecular Sciences. 2020, 21, 3035
]
.
Platelet activation by thrombin
Thrombin is one of the key platelet activators and the key enzyme of the blood coagulation system. Thrombin activates platelets by binding to PAR (Protease-Activated Receptors). On the surface of platelets, there are two kinds of these GPCRs: PAR1 and PAR4 in humans and PAR3 and PAR4 in mice. Thrombin cuts off a small oligopeptide from the N-terminus of these receptors, which subsequently activates the corresponding receptor
[
81
Domains specifying thrombin–receptor interaction
T. Vu, V. Wheaton, D. Hung, I. Charo, S. Coughlin
Nature. 1991, 353, 674-677
]
and leads to instant platelet activation. For humans, the PAR1 receptor is considered to be the most important one since it has a higher affinity for thrombin than PAR4 (50-200 pM and 10-100 nM, respectively). PARs activate Gq-
[
23
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
]
and possibly G12/13
[
82
RhoA downstream of Gq and G12/13 pathways regulates protease-activated receptor-mediated dense granule release in platelets
J. Jin, Y. Mao, D. Thomas, S. Kim, J. Daniel, S. Kunapuli
Biochemical Pharmacology. 2009, 77, 835-844
]
. Gq signaling leads to an increase in the concentration of free calcium ions in the cell cytosol. At thrombin concentrations even of the order of 0.1 nM, the concentration of calcium ions in platelets can instantly increase tenfold. As we showed earlier
[
23
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
]
, platelets need a pair of receptors with similar signaling pathways in order to expand the range of sensitivity to thrombin (together PAR1 and PAR4 are able to distinguish from 0.1 to 100 nM thrombin) and to increase the duration of the calcium response while maintaining a rapid initial response.
It is known that thrombin can cause the decrease of the concentration of cAMP in platelets via inhibition of adenylate cyclase (which catalyzes the conversion of ATP to cAMP) through the Gi protein associated with the thrombin receptor, or indirectly, via promoting the release of ADP, and an increase in the activity of phosphodiesterases (enzymes that catalyze the hydrolysis of cAMP in AMP). However, it is assumed that this effect is mediated by the P2Y12 receptor activation by secreted ADP
[
21,
Platelet Secretion. In: Michelson AD, editor. Platelets (Fourth Edition)
Flaumenhaft R, Sharda A
Academic Press. 2019, None, 349-70
41
Platelet Signal Transduction. In: Michelson AD, editor. Platelets (Fourth Edition)
Lee RH, Stefanini L, Bergmeier W.
Academic Press. 2019, None, 329-48
]
.
In addition to PAR receptors, thrombin can bind GPIb-V-IX. It is assumed that binding to GPIb enhances thrombin affinity to PAR receptors, dramatically accelerating their proteolysis, thereby accelerating PAR-dependent platelet activation
[
83
Primary haemostasis: newer insights
M. Berndt, P. Metharom, R. Andrews
Haemophilia. 2014, 20, 15-22
]
.
Thrombin is one of the most potent platelet activators and leads to platelet aggregation, the release of ADP and ATP, synthesis of thromboxane A2 (TxA2), and, like collagen, can lead to the strongest degree of platelet activation - procoagulant activity. These signaling paths will be described later.
АDP-induced platelet activation
ADP is contained in dense platelet granules, which are secreted upon platelet activation
[
84
New Fundamentals in Hemostasis
H. Versteeg, J. Heemskerk, M. Levi, P. Reitsma
Physiological Reviews. 2013, 93, 327-358
]
. Vascular endothelial cells, if damaged, also release the ADP they contain. When ADP is added to the system in vitro, platelet phospholipase A2 (PLA2) and cyclooxygenase 1 (COX1) become activated and produce TxA2 from arachidonic acid
[
85
Adenosine diphosphate (ADP)–induced thromboxane A2generation in human platelets requires coordinated signaling through integrin αIIbβ3 and ADP receptors
J. Jin, T. Quinton, J. Zhang, S. Rittenhouse, S. Kunapuli
Blood. 2002, 99, 193-198
]
. ADP also triggers calcium signaling, shape changes, protein phosphorylation, and platelet aggregation
[
86
Mechanisms of platelet activation: Need for new strategies to protect against platelet-mediated atherothrombosis
L. Jennings
Thrombosis and Haemostasis. 2009, 102, 248-257
]
. Platelet aggregation upon ADP stimulation increases in a dose-dependent manner
[
87
Platelet adhesion, shape change, and aggregation: rapid initiation and signal transduction events
A. Gear
Canadian Journal of Physiology and Pharmacology. 1994, 72, 285-294
]
. Thus, in case of damage to the blood vessel wall, numerous platelets become activated, and ADP is released to the blood flow, activating other platelets.
There are two types of ADP receptors on the platelet surface, P2Y1, and P2Y12, both of which are GPCRs
[
88
Defective platelet activation in Gαq-deficient mice
S. Offermanns, C. Toombs, Y. Hu, M. Simon
Nature. 1997, 389, 183-186
]
. Resting platelets have about 160 P2Y1 receptors and 745 P2Y12 receptors on the surface
[
17
The first comprehensive and quantitative analysis of human platelet protein composition allows the comparative analysis of structural and functional pathways
J. Burkhart, M. Vaudel, S. Gambaryan, S. Radau, U. Walter, L. Martens, J. Geiger, A. Sickmann, R. Zahedi
Blood. 2012, 120, e73-e82
]
. When platelets become activated by a strong activator (thrombin or collagen), the number of these receptors on the platelet surface increases because these receptors are contained in its α-granules, secreted by the platelets upon activation
[
21
Platelet Secretion. In: Michelson AD, editor. Platelets (Fourth Edition)
Flaumenhaft R, Sharda A
Academic Press. 2019, None, 349-70
]
.
The P2Y1 receptor transmits a signal via the Gq protein, which leads to the same platelet signaling as thrombin, yet significantly less strong
[
80
Heterogeneity of Integrin αIIbβ3 Function in Pediatric Immune Thrombocytopenia Revealed by Continuous Flow Cytometry Analysis
A. Martyanov, D. Morozova, M. Sorokina, A. Filkova, D. Fedorova, S. Uzueva, E. Suntsova, G. Novichkova, P. Zharkov, M. Panteleev, A. Sveshnikova
International Journal of Molecular Sciences. 2020, 21, 3035
]
. The binding of ADP to the P2Y12 receptor leads to the activation of the Gi protein, which causes inhibition of adenylate cyclase and a decrease in the level of cAMP in the cell, as described above. In the absence or blockage of the P2Y1 receptor, ADP is still able to inhibit the formation of cAMP, but its ability to induce calcium mobilization, change the shape of platelets, and their aggregation is greatly reduced. In P2Y1-/- mice, there is a slight increase in bleeding time and resistance to ADP-induced thromboembolism. On the other hand, these mice do not have a predisposition to spontaneous bleeding
[
18
Platelet signaling
Stalker TJ, Newman DK, Ma P, Wannemacher KM, Brass LF
Handbook of Experimental Pharmacology. 2012, None, 59-85
]
. Platelets from P2Y12-/- mice are unable to aggregate normally in response to ADP administration. They retain the ability to change their shape and PLC activation, but this is due to the normal functioning of the P2Y1 receptor. In such platelets, a decrease in the ability to inhibit the formation of cAMP in response to ADP is observed
[
18
Platelet signaling
Stalker TJ, Newman DK, Ma P, Wannemacher KM, Brass LF
Handbook of Experimental Pharmacology. 2012, None, 59-85
]
.
Considering ADP as a platelet activator, it should be noted that in plasma, ADP is hydrolyzed to AMP with a half-life of 10-15 minutes, which affects the number of platelets that it can activate. Hydrolysis of ADP in plasma occurs under the action of ADPase, which is produced by lymphocytes and endothelial cells
[
89
Metabolism of adenine nucleotides in human blood.
S. Coade, J. Pearson
Circulation Research. 1989, 65, 531-537
]
. Erythrocytes also participate in ADP hydrolysis
[
90
Demonstration of a novel ecto-enzyme on human erythrocytes, capable of degrading ADP and of inhibiting ADP-induced platelet aggregation
J. LUTHJE, A. SCHOMBURG, A. OGILVIE
European Journal of Biochemistry. 1988, 175, 285-289
]
. This process is necessary for the prevention of the spontaneous activation of platelets in blood circulation.
Platelet activation by TxA2, serotonin, and adrenaline
TxA2 is also a weak platelet activator and is considered an even weaker activator than ADP. Upon addition of TxA2 (or its stable analog U46619), platelets in vitro exhibit all functional responses except for the procoagulant
[
86
Mechanisms of platelet activation: Need for new strategies to protect against platelet-mediated atherothrombosis
L. Jennings
Thrombosis and Haemostasis. 2009, 102, 248-257
]
. The TP receptor is the only receptor for TxA2 on the platelet surface. It is associated with Gq and G12/13 proteins, with signal transmission pathways being completely identical to those described above
[
18
Platelet signaling
Stalker TJ, Newman DK, Ma P, Wannemacher KM, Brass LF
Handbook of Experimental Pharmacology. 2012, None, 59-85
]
. When a platelet is activated by a strong activator (thrombin or collagen), the number of these receptors on the platelet surface increases because these receptors are contained in its α-granules
[
91
The evolution of megakaryocytes to platelets
P. Nurden, C. Poujol, A. Nurden
Baillière's Clinical Haematology. 1997, 10, 1-27
]
.
In TP-/- mice, prolonged bleeding time was observed. Their platelets were unable to aggregate in response to TxA2 administration, and their aggregation time in response to collagen was increased. In vitro, in the presence of aspirin (inhibitor of TxA2 synthesis), platelet responses to ADP or collagen are impaired. The defect in response to thrombin looks like a shift in the concentration/aggregation curve, which indicates that TxA2 synthesis only supports platelet activation from thrombin but is not required for this process
[
18
Platelet signaling
Stalker TJ, Newman DK, Ma P, Wannemacher KM, Brass LF
Handbook of Experimental Pharmacology. 2012, None, 59-85
]
.
Platelet activation by TxA2 does not cause synthesis and release of TxA2
[
92
Possible involvement of cytoskeleton in collagen-stimulated activation of phospholipases in human platelets
Nakano T, Hanasaki K, Arita H.
Journal of Biological Chemistry. 1989, 264, 5400-6
]
, but single platelet secretes about 10-8 nmol of ADP contained in dense granules, with a characteristic release time of about 5 seconds
[
93
Detection of local ATP release from activated platelets using cell surface-attached firefly luciferase
R. Beigi, E. Kobatake, M. Aizawa, G. Dubyak
American Journal of Physiology-Cell Physiology. 1999, 276, C267-C278
]
. In the presence of platelets, TxA2 is hydrolyzed to thromboxane B2 (its half-life is about 30 seconds)
[
94
Persistence of thromboxane A2-like material and platelet release-inducing activity in plasma.
J. Smith, C. Ingerman, M. Silver
Journal of Clinical Investigation. 1976, 58, 1119-1122
]
, which severely limits its area of distribution and the number of platelets that it can activate.
Currently, the TxA2 signaling cascade in platelets is not completely understood. It is not clear why TxA2 synthesis is not initiated upon platelet activation by TxA2, although intracellular events, in this case, are completely identical to the case of platelet activation by ADP. It is possible that the short-lived TxA2 plays the role of a weak initiator of the platelet activation process, while the longer-lived ADP enhances this process and expands the platelet activation area.
Adrenaline and serotonin may also play a significant role in platelet activation
[
95
Signaling During Platelet Adhesion and Activation
Z. Li, M. Delaney, K. O'Brien, X. Du
Arteriosclerosis, Thrombosis, and Vascular Biology. 2010, 30, 2341-2349
]
. Serotonin is contained in dense platelet granules and is secreted when activated. It has also been shown that platelets are one of the main stores of serotonin in the bloodstream of mammals
[
96
Molecular Mechanisms of SERT in Platelets: Regulation of Plasma Serotonin Levels
C. Mercado, F. Kilic
Molecular Interventions. 2010, 10, 231-241
]
. Serotonin induces platelet activation in a Gq-dependent manner, triggering calcium responses via PLCb
[
95,
Signaling During Platelet Adhesion and Activation
Z. Li, M. Delaney, K. O'Brien, X. Du
Arteriosclerosis, Thrombosis, and Vascular Biology. 2010, 30, 2341-2349
97
Epinephrine restores platelet functions inhibited by ticagrelor: A mechanistic approach
A. Martin, D. Zlotnik, G. Bonete, E. Baron, B. Decouture, T. Belleville-Rolland, B. Le Bonniec, S. Poirault-Chassac, M. Alessi, P. Gaussem, A. Godier, C. Bachelot-Loza
European Journal of Pharmacology. 2020, 866, 172798
]
. It has been shown that in patients with serotonin reuptake inhibitors (inhibitors of SERT pumps), which are used in depression treatment, platelet aggregation is impaired
[
96
Molecular Mechanisms of SERT in Platelets: Regulation of Plasma Serotonin Levels
C. Mercado, F. Kilic
Molecular Interventions. 2010, 10, 231-241
]
. The adrenaline agonist on platelets is the adrenergic receptor, which induces similar signaling with the P2Y12 receptor: a2-receptor inhibits the activity of adenylate cyclase via Gi and thus potentiates platelet activation
[
95
Signaling During Platelet Adhesion and Activation
Z. Li, M. Delaney, K. O'Brien, X. Du
Arteriosclerosis, Thrombosis, and Vascular Biology. 2010, 30, 2341-2349
]
.
Receptors that cause tyrosine-kinase signaling
The second important signaling branch in platelets is tyrosine kinase signaling. Tyrosine kinase signaling in platelets is built around a cascade of tyrosine kinases, which phosphorylate both each other and the surrounding effector proteins
[
98,
Platelet ITAM signaling
W. Bergmeier, L. Stefanini
Current Opinion in Hematology. 2013, 20, 445-450
101
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
]
. Each of these tyrosine kinases has a complex domain structure that determines the mechanisms of their activation and regulation
[
100,
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
101
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
]
. Simultaneously, an equally important role is played by enzymes that reverse tyrosine phosphorylation - tyrosine phosphatases, which control both activation and inhibitory signals
[
101,
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
102
Dominant Role of the Protein-Tyrosine Phosphatase CD148 in Regulating Platelet Activation Relative to Protein-Tyrosine Phosphatase-1B
J. Mori, Y. Wang, S. Ellison, S. Heising, B. Neel, M. Tremblay, S. Watson, Y. Senis
Arteriosclerosis, Thrombosis, and Vascular Biology. 2012, 32, 2956-2965
]
. Despite the wide variety of tyrosine kinases, most of the regulatory domains responsible for their regulation are similar
[
100
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
]
. The most widespread regulatory domains are:calcium-binding domains (C2-domain, EF- "handles"); domains that recognize certain amino acid sequences (SH2, SH3, immunoglobulin-like domains, DED); membrane-binding domains (PH, SH4, C1); aactin-bindingdomains (REM; FH2)
[
100,
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
103
Mechanisms of receptor tyrosine kinase activation in cancer
Z. Du, C. Lovly
Molecular Cancer. 2018, 17, None
]
.
The key kinases required for the initiation of tyrosine kinase signaling in platelets are the tyrosine kinases of the SFK family, as well as the kinases Syk and Btk. Tyrosine kinases of the SFK family, which include Src, Fyn, and Lyn in platelets
[
101
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
]
, are graduated “switches”: activation of their domains leads to an increase in their activity. These kinases consist of 4 main domains: a catalytic domain that conducts phosphorylation, as well as three regulatory domains SH2, SH3, SH4
[
100,
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
101
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
]
. The SH2 domain of SFK kinases allows them to bind to phosphorylated tyrosine residues on other proteins, for example, in phosphorylated YxxL sequences, which are called immune tyrosine-activated motifs (ITAM)
[
104
SH2 domains: modulators of nonreceptor tyrosine kinase activity
P. Filippakopoulos, S. Müller, S. Knapp
Current Opinion in Structural Biology. 2009, 19, 643-649
]
. The SH3 domain is required for SFK binding to polyproline regions (xPPxP) in proteins
[
105
SH3 domain ligand binding: What's the consensus and where's the specificity?
K. Saksela, P. Permi
FEBS Letters. 2012, 586, 2609-2614
]
: for example, due to SH3 domains, SFK kinases can associate with BCR and GPVI receptors, the cytoplasmic domains of which contain polyproline-enriched sequences
[
106
Molecular priming of Lyn by GPVI enables an immune receptor to adopt a hemostatic role
A. Schmaier, Z. Zou, A. Kazlauskas, L. Emert-Sedlak, K. Fong, K. Neeves, S. Maloney, S. Diamond, S. Kunapuli, J. Ware, L. Brass, T. Smithgall, K. Saksela, M. Kahn
Proceedings of the National Academy of Sciences. 2009, 106, 21167-21172
]
. Finally, the SH4 domain of SFK kinases is required for their localization in the juxta-membrane regions: SH4 is attached to palmitoic or meristoic acid residues, which are hydrophobic and, therefore, allow SFK to be “anchored” in the membrane
[
101
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
]
. SFK activation usually occurs according to the following scheme: initially, SFKs are in an autoinhibited state. Then CD148 phosphatase dephosphorylates them, which translates them into an active state
[
100,
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
101
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
]
. Then, SFKs can SH3, and SH2 domains can attach to target proteins (for example, to receptors), which will transfer them to the ¾ active state. Thereafter, unfolded SFKs can become maximally active by autophosphorylation
[
100
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
]
. It is noteworthy that the reaction opposite to the maximum activation reaction is carried out by the same phosphatase CD148 as the initial one
[
100
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
]
.
Syk tyrosine kinases are OR switches - they can be activated by activating one of the two regulatory sites. The structure of Syk kinases is less complex than the structure of SFK kinases: Syk consists of three domains: one catalytic and two SH2 domains
[
107
Molecular Mechanism of the Syk Activation Switch
E. Tsang, A. Giannetti, D. Shaw, M. Dinh, J. Tse, S. Gandhi, H. Ho, S. Wang, E. Papp, J. Bradshaw
Journal of Biological Chemistry. 2008, 283, 32650-32659
]
. Syk is activated by simultaneous binding of two of their SH2 domains to phosphorylated tyrosine residues in YxxL sequences
[
100,
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
107
Molecular Mechanism of the Syk Activation Switch
E. Tsang, A. Giannetti, D. Shaw, M. Dinh, J. Tse, S. Gandhi, H. Ho, S. Wang, E. Papp, J. Bradshaw
Journal of Biological Chemistry. 2008, 283, 32650-32659
]
, or Syk can be activated by phosphorylation of their linker domain between the kinase and the first of the SH2 domains
[
107
Molecular Mechanism of the Syk Activation Switch
E. Tsang, A. Giannetti, D. Shaw, M. Dinh, J. Tse, S. Gandhi, H. Ho, S. Wang, E. Papp, J. Bradshaw
Journal of Biological Chemistry. 2008, 283, 32650-32659
]
. This reaction can be carried out by both representatives of SFK and active Syk
[
108
The N-terminal SH2 domain of Syk is required for (hem)ITAM, but not integrin, signaling in mouse platelets
C. Hughes, B. Finney, F. Koentgen, K. Lowe, S. Watson
Blood. 2015, 125, 144-154
]
.
Tyrosine kinases Btk and Tec
[
100
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
]
are "AND" type switches - for their activation, several conditions must be met at once
[
100
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
]
. Btk tyrosine kinases are composed of PH, SH3, SH2, and kinase domains
[
100
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
]
. During the production of PIP3, Btk is localized on the plasma membrane, and their SH2 domain binds to phosphotyrosine
[
41,
Platelet Signal Transduction. In: Michelson AD, editor. Platelets (Fourth Edition)
Lee RH, Stefanini L, Bergmeier W.
Academic Press. 2019, None, 329-48
45
Impact of the PI3-kinase/Akt pathway on ITAM and hemITAM receptors: Haemostasis, platelet activation and antithrombotic therapy
A. Moroi, S. Watson
Biochemical Pharmacology. 2015, 94, 186-194
]
, while SH3, as suggested by
[
100,
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
101
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
]
, may be required to attract other proteins containing polyproline
[
109
Dynamics of the Tec-family tyrosine kinase SH3 domains
J. Roberts, S. Tarafdar, R. Joseph, A. Andreotti, T. Smithgall, J. Engen, T. Wales
Protein Science. 2016, 25, 852-864
]
. All these events lead to the activation of Btk, which, in turn, lead to the activation of PLCγ2, which are also localized in this region due to their SH2 domains and additional adapters vav and SLP-76
[
45,
Impact of the PI3-kinase/Akt pathway on ITAM and hemITAM receptors: Haemostasis, platelet activation and antithrombotic therapy
A. Moroi, S. Watson
Biochemical Pharmacology. 2015, 94, 186-194
98
Platelet ITAM signaling
W. Bergmeier, L. Stefanini
Current Opinion in Hematology. 2013, 20, 445-450
]
. Currently, several pharmacological inhibitors of Btk kinases are used in clinics for the treatment of leukemia
[
110
Ibrutinib-associated bleeding: pathogenesis, management and risk reduction strategies
J. Shatzel, S. Olson, D. Tao, O. McCarty, A. Danilov, T. DeLoughery
Journal of Thrombosis and Haemostasis. 2017, 15, 835-847
]
.
The activation of tyrosine kinases is the first step in initiating the assembly of signalosomes — large protein complexes — centcentersintracellular signal propagation
[
111
The transmembrane adapter LAT plays a central role in immune receptor signalling
P. Wonerow, S. Watson
Oncogene. 2001, 20, 6273-6283
]
. During tyrosine kinase signaling in platelets, the signalosome is based on the adapter protein LAT, which has a large number of phosphorylation sites
[
30
Control of Platelet CLEC-2-Mediated Activation by Receptor Clustering and Tyrosine Kinase Signaling
A. Martyanov, F. Balabin, J. Dunster, M. Panteleev, J. Gibbins, A. Sveshnikova
Biophysical Journal. 2020, 118, 2641-2655
]
. Type I PI3K binds to phospho-LAT by the regulatory (p85) subunit, which has two SH2 domains. This leads to the unfolding and activation of the catalytic subunit p110, which, in turn, phosphorylates the membrane phosphoinositide PIP2, producing PIP3
[
45
Impact of the PI3-kinase/Akt pathway on ITAM and hemITAM receptors: Haemostasis, platelet activation and antithrombotic therapy
A. Moroi, S. Watson
Biochemical Pharmacology. 2015, 94, 186-194
]
. PIP3 is a substrate for the PH domain, which determines the docking on the plasma membrane of a number of components of the platelet tyrosine kinase signaling network, including Btk and PLCγ2
[
41,
Platelet Signal Transduction. In: Michelson AD, editor. Platelets (Fourth Edition)
Lee RH, Stefanini L, Bergmeier W.
Academic Press. 2019, None, 329-48
100
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
]
.
It is important to note that not only kinases but also phosphatases play an important role in the activation of tyrosine kinase signaling. Thus, in addition to CD148, SFK can also be regulated by PTP1B and DUSP3 phosphatases, which are activated during the propagation of the activation signal by phosphorylation
[
102,
Dominant Role of the Protein-Tyrosine Phosphatase CD148 in Regulating Platelet Activation Relative to Protein-Tyrosine Phosphatase-1B
J. Mori, Y. Wang, S. Ellison, S. Heising, B. Neel, M. Tremblay, S. Watson, Y. Senis
Arteriosclerosis, Thrombosis, and Vascular Biology. 2012, 32, 2956-2965
112
Dual-Specificity Phosphatase 3 Deficiency or Inhibition Limits Platelet Activation and Arterial Thrombosis
L. Musumeci, M. Kuijpers, K. Gilio, A. Hego, E. Théâtre, L. Maurissen, M. Vandereyken, C. Diogo, C. Lecut, W. Guilmain, E. Bobkova, J. Eble, R. Dahl, P. Drion, J. Rascon, Y. Mostofi, H. Yuan, E. Sergienko, T. Chung, M. Thiry, Y. Senis, M. Moutschen, T. Mustelin, P. Lancellotti, J. Heemskerk, L. Tautz, C. Oury, S. Rahmouni
Circulation. 2015, 131, 656-668
]
. PTP1B is associated with the membrane of the endoplasmic reticulum and starts to participate when the platelet shape changes and intracellular organelles come to those in proximity to the plasma membrane
[
102
Dominant Role of the Protein-Tyrosine Phosphatase CD148 in Regulating Platelet Activation Relative to Protein-Tyrosine Phosphatase-1B
J. Mori, Y. Wang, S. Ellison, S. Heising, B. Neel, M. Tremblay, S. Watson, Y. Senis
Arteriosclerosis, Thrombosis, and Vascular Biology. 2012, 32, 2956-2965
]
. On the other hand, negative regulators of activation, in particular, SHP-1,2 phosphatase, also play an important role. SHP-1,2 possepossessesSH2 domains that can associate with phosphorylated tyrosines in immune tyrosine inhibitory motives (ITIMs). Activated SHPs perform ITAM dephosphorylation
[
113
ITIM receptors: more than just inhibitors of platelet activation
C. Coxon, M. Geer, Y. Senis
Blood. 2017, 129, 3407-3418
]
. Phosphorylation of ITIM also leads to the activation of SHIP1,2, which carry out a reaction opposite to the reaction catalyzed by PI3K - dephosphorylate PIP3, thus inhibiting the activation of Btk
[
47
Different roles of SHIP1 according to the cell context: The example of blood platelets
M. Gratacap, S. Séverin, G. Chicanne, M. Plantavid, B. Payrastre
Advances in Enzyme Regulation. 2008, 48, 240-252
]
.
Receptors that induce or inhibit tyrosine kinase signaling
There are 3 types of receptors on human platelets that trigger the activation of the tyrosine kinase cascade: the collagen GPVI receptor, the podoplanin receptor CLEC-2, and the immunoglobulin G receptor FcgRIIa
[
98,
Platelet ITAM signaling
W. Bergmeier, L. Stefanini
Current Opinion in Hematology. 2013, 20, 445-450
99
Platelet Immunoreceptor Tyrosine-Based Activation Motif (ITAM) Signaling and Vascular Integrity
Y. Boulaftali, P. Hess, M. Kahn, W. Bergmeier
Circulation Research. 2014, 114, 1174-1184
]
. Each of these receptors triggers a similar signaling cascade, but the specific features of their intracellular structure determine the characteristic times and the degree of strength of platelet activation when stimulated through them. Each of these receptors carries in its cytoplasmic domain one (CLEC-2)
[
114
Functional significance of the platelet immune receptors GPVI and CLEC-2
J. Rayes, S. Watson, B. Nieswandt
Journal of Clinical Investigation. 2019, 129, 12-23
]
or several (FcgRIIa) YxxL sequences
[
98
Platelet ITAM signaling
W. Bergmeier, L. Stefanini
Current Opinion in Hematology. 2013, 20, 445-450
]
– ITAM and hemITAM, respectively. YxxL sequences can also be on receptor-associated proteins, for example, the cytoplasmic domain of GPVI is covalently linked to the FcgR chain carrying ITAM
[
115
GPVI and CLEC-2 in hemostasis and vascular integrity
S. WATSON, J. HERBERT, A. POLLITT
Journal of Thrombosis and Haemostasis. 2010, 8, 1456-1467
]
. It is important to note that the tyrosine kinase signaling branch in human and mouse platelets is significantly different: for example, FcgRIIa is absent on mouse platelets
[
116
Human platelet IgG Fc receptor FcγRIIA in immunity and thrombosis
M. Arman, K. Krauel
Journal of Thrombosis and Haemostasis. 2015, 13, 893-908
]
. Tyrosine kinase signaling in platelets can also be triggered by the receptor tyrosine kinases EphA4 and EphB1, which are activated by ephrin. It has been shown that their activation leads to adhesion and aggregation of platelets to fibrinogen. The key elements of the signaling cascade of these receptors are PI3K
[
117
Signaling by ephrinB1 and Eph kinases in platelets promotes Rap1 activation, platelet adhesion, and aggregation via effector pathways that do not require phosphorylation of ephrinB1
N. Prévost, D. Woulfe, M. Tognolini, T. Tanaka, W. Jian, R. Fortna, H. Jiang, L. Brass
Blood. 2004, 103, 1348-1355
]
.
Besides activating tyrosine kinase-dependent receptors on the surface of platelets, inhibitory tyrosine kinase receptors are also present, which carry the ITIM and ITSM sequences in their cytoplasmic domains
[
113,
ITIM receptors: more than just inhibitors of platelet activation
C. Coxon, M. Geer, Y. Senis
Blood. 2017, 129, 3407-3418
118
SLAM Family Receptors and SAP Adaptors in Immunity
J. Cannons, S. Tangye, P. Schwartzberg
Annual Review of Immunology. 2011, 29, 665-705
]
. The most studied among them are the PECAM-1 (CD31) and G6b receptors
[
113
ITIM receptors: more than just inhibitors of platelet activation
C. Coxon, M. Geer, Y. Senis
Blood. 2017, 129, 3407-3418
]
. It is believed that these receptors are necessary to limit platelet activation: for example, a platelet that interacted with a thrombus, but did not adhere to it, can return to a resting state largely due to the activity of PECAM-1 and G6b-B
[
113
ITIM receptors: more than just inhibitors of platelet activation
C. Coxon, M. Geer, Y. Senis
Blood. 2017, 129, 3407-3418
]
. However, the mechanisms by which these receptors limit activation vary.
PECAM-1 is present not only on platelets but also on leukocytes and endotheliocytes
[
119
Platelet Inhibitory Receptors. In: Michelson AD, editor. Platelets (Fourth Edition)
Nagy Z, Senis YA
Academic Press. 2019, None, 279-93
]
. It has been shown that platelet PECAM-1 is involved in the interaction of platelets and endothelial cells, acting as an adhesion molecule
[
119
Platelet Inhibitory Receptors. In: Michelson AD, editor. Platelets (Fourth Edition)
Nagy Z, Senis YA
Academic Press. 2019, None, 279-93
]
. In resting platelets, ITSM is hidden in its cytoplasmic domain; however, upon platelet activation, the serine residue in the near-membrane region of PECAM-1 is phosphorylated
[
120
Minimal regulation of platelet activity by PECAM-1
T. Dhanjal, E. Ross, J. Auger, O. Mccarty, C. Hughes, Y. Senis, S. Watson
Platelets. 2007, 18, 56-67
]
. This leads to the unfolding of the PECAM-1 cytoplasmic domain and the release of ITIM and ITSM, which can then be phosphorylated by SFK
[
121
Collagen, Convulxin, and Thrombin Stimulate Aggregation-independent Tyrosine Phosphorylation of CD31 in Platelets
M. Cicmil, J. Thomas, T. Sage, F. Barry, M. Leduc, C. Bon, J. Gibbins
Journal of Biological Chemistry. 2000, 275, 27339-27347
]
. It has been demonstrated in vitro that ITIM and ITSM are phosphorylated upon stimulation of platelets by thrombin or collagen
[
121
Collagen, Convulxin, and Thrombin Stimulate Aggregation-independent Tyrosine Phosphorylation of CD31 in Platelets
M. Cicmil, J. Thomas, T. Sage, F. Barry, M. Leduc, C. Bon, J. Gibbins
Journal of Biological Chemistry. 2000, 275, 27339-27347
]
. SHP-1 or SHP-2 phosphatases, which carry two SH-2 motifs, attach to the ITIM-ITSM motifs of PECAM-1. This leads to their activation: active SHP-1 and SHP-2 dephosphorylate ITAM motifs, Syk kinases, SFK kinases, and LAT adapters
[
122
Thrombin-induced association of SHP-2 with multiple tyrosine-phosphorylated proteins in human platelets
C. Edmead, D. Crosby, M. Southcott, A. Poole
FEBS Letters. 1999, 459, 27-32
]
. It has been shown that SHIP-1 and SHIP-2 can also bind to PECAM-1
[
123
Differential association of cytoplasmic signalling molecules SHP-1, SHP-2, SHIP and phospholipase C-γ1 with PECAM-1/CD31
N. Pumphrey, V. Taylor, S. Freeman, M. Douglas, P. Bradfield, S. Young, J. Lord, M. Wakelam, I. Bird, M. Salmon, C. Buckley
FEBS Letters. 1999, 450, 77-83
]
. However, there is no reliable data that they are actively involved in the propagation of the inhibitory signal.
The cytoplasmic domain G6b-B also consists of two ITAM-ISTM motifs. However, unlike PECAM-1, G6b-B is constantly available for phosphorylation by SFK kinases
[
124
Maintenance of murine platelet homeostasis by the kinase Csk and phosphatase CD148
J. Mori, Z. Nagy, G. Di Nunzio, C. Smith, M. Geer, R. Al Ghaithi, J. van Geffen, S. Heising, L. Boothman, B. Tullemans, J. Correia, L. Tee, M. Kuijpers, P. Harrison, J. Heemskerk, G. Jarvis, A. Tarakhovsky, A. Weiss, A. Mazharian, Y. Senis
Blood. 2018, 131, 1122-1144
]
. Thus, G6b-B is phosphorylated not only in activated cells but in resting cells as well, and the proportion of SHP-1 and SHP-2 phosphatases is maintained in a constantly active state
[
124
Maintenance of murine platelet homeostasis by the kinase Csk and phosphatase CD148
J. Mori, Z. Nagy, G. Di Nunzio, C. Smith, M. Geer, R. Al Ghaithi, J. van Geffen, S. Heising, L. Boothman, B. Tullemans, J. Correia, L. Tee, M. Kuijpers, P. Harrison, J. Heemskerk, G. Jarvis, A. Tarakhovsky, A. Weiss, A. Mazharian, Y. Senis
Blood. 2018, 131, 1122-1144
]
. There are also hypotheses according to which phosphorylation of G6b-B can be enhanced by binding to heparan sulfate. Thus, unlike PECAM-1, which is mainly an activation-limiting receptor, G6b-B is rather an activation threshold that does not allow platelets to become activated when signals are too weak
[
125
An Investigation of Hierachical Protein Recruitment to the Inhibitory Platelet Receptor, G6B-b
C. Coxon, A. Sadler, J. Huo, R. Campbell
PLoS ONE. 2012, 7, e49543
]
.
GPVI – key platelet receptor for collagen
GPVI is a membrane glycoprotein that recognizes several glycine-proline-hydroxyproline (GPO) sequences characteristic of collagen
[
115
GPVI and CLEC-2 in hemostasis and vascular integrity
S. WATSON, J. HERBERT, A. POLLITT
Journal of Thrombosis and Haemostasis. 2010, 8, 1456-1467
]
. The role of GPVI in platelet activation by fibrin
[
126
Fibrin and D-dimer bind to monomeric GPVI
M. Onselaer, A. Hardy, C. Wilson, X. Sanchez, A. Babar, J. Miller, C. Watson, S. Watson, A. Bonna, H. Philippou, A. Herr, D. Mezzano, R. Ariëns, S. Watson
Blood Advances. 2017, 1, 1495-1504
]
, fibrinogen
[
127
Pharmacological Blockade of Glycoprotein VI Promotes Thrombus Disaggregation in the Absence of Thrombin
M. Ahmed, V. Kaneva, S. Loyau, D. Nechipurenko, N. Receveur, M. Le Bris, E. Janus-Bell, M. Didelot, A. Rauch, S. Susen, N. Chakfé, F. Lanza, E. Gardiner, R. Andrews, M. Panteleev, C. Gachet, M. Jandrot-Perrus, P. Mangin
Arteriosclerosis, Thrombosis, and Vascular Biology. 2020, 40, 2127-2142
]
and “outside-in” activation of fibrinogen-clustered integrins
[
99,
Platelet Immunoreceptor Tyrosine-Based Activation Motif (ITAM) Signaling and Vascular Integrity
Y. Boulaftali, P. Hess, M. Kahn, W. Bergmeier
Circulation Research. 2014, 114, 1174-1184
128
Integrin αIIbβ3. In: Michelson AD, editor. Platelets (Fourth Edition)
Bledzka K, Qin J, Plow EF.
Academic Press. 2019, None, 227–41
]
has been reported. GPVI activation requires receptor clustering
[
115,
GPVI and CLEC-2 in hemostasis and vascular integrity
S. WATSON, J. HERBERT, A. POLLITT
Journal of Thrombosis and Haemostasis. 2010, 8, 1456-1467
129
Comparison of the GPVI inhibitors losartan and honokiol
M. Onselaer, M. Nagy, C. Pallini, J. Pike, G. Perrella, L. Quintanilla, J. Eble, N. Poulter, J. Heemskerk, S. Watson
Platelets. 2020, 31, 187-197
]
, the mechanism of which is not fully elucidated
[
130
Clustering of glycoprotein VI (GPVI) dimers upon adhesion to collagen as a mechanism to regulate GPVI signaling in platelets
N. Poulter, A. Pollitt, D. Owen, E. Gardiner, R. Andrews, H. Shimizu, D. Ishikawa, D. Bihan, R. Farndale, M. Moroi, S. Watson, S. Jung
Journal of Thrombosis and Haemostasis. 2017, 15, 549-564
]
. Lipid rafts, membrane regions enriched with cholesterol and sphingomyelin, in which diffusion is significantly slowed down, play an important role in the clustering of platelet GPVIs
[
131
Function of Platelet Glycosphingolipid Microdomains/Lipid Rafts
K. Komatsuya, K. Kaneko, K. Kasahara
International Journal of Molecular Sciences. 2020, 21, 5539
]
. A large number of signaling molecules are associated with lipid rafts, among which are LAT and SFK kinases
[
101
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
]
.
The cytoplasmic domain of GPVI is associated through salt bridges with the ITAM-containing FcgR chain, on which ITAM is present
[
98
Platelet ITAM signaling
W. Bergmeier, L. Stefanini
Current Opinion in Hematology. 2013, 20, 445-450
]
. Through SH3 domains, SFK kinases are associated with GPVI, which are maintained in an active state by CD148 phosphatases
[
101
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
]
. Upon activation and clustering of GPVI SFKs phosphorylate ITAMs of the nearby GPVI-FcgR complexes
[
45,
Impact of the PI3-kinase/Akt pathway on ITAM and hemITAM receptors: Haemostasis, platelet activation and antithrombotic therapy
A. Moroi, S. Watson
Biochemical Pharmacology. 2015, 94, 186-194
115
GPVI and CLEC-2 in hemostasis and vascular integrity
S. WATSON, J. HERBERT, A. POLLITT
Journal of Thrombosis and Haemostasis. 2010, 8, 1456-1467
]
. Syk kinases bind to phosphorylated ITAMs, thus becoming active
[
100
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
]
. Due to the ability of Syk to autophosphorylation, positive feedback arises that accelerates the activation of Syk in the cytosol (Fig. 3). Active Syk phosphorylates LAT, to which vav1/3, SLP-76, PLCg2, and PI3K bind with their SH-2 domains, forming the signalosome
[
45
Impact of the PI3-kinase/Akt pathway on ITAM and hemITAM receptors: Haemostasis, platelet activation and antithrombotic therapy
A. Moroi, S. Watson
Biochemical Pharmacology. 2015, 94, 186-194
]
. PI3K activated in this process phosphorylates PIP2, producing PIP3 and thus attracting Btk
[
132
Role of PI3K/Akt signaling in memory CD8 T cell differentiation
E. Kim, M. Suresh
Frontiers in Immunology. 2013, 4, None
]
. Btk trapped in the signalosome are activated and trigger the activation of PLCg2, which hydrolyzes PIP2 to DAG and IP3. IP3 further triggers calcium signaling in platelets
[
114
Functional significance of the platelet immune receptors GPVI and CLEC-2
J. Rayes, S. Watson, B. Nieswandt
Journal of Clinical Investigation. 2019, 129, 12-23
]
.
CLEC-2 – a receptor that is required for the prevention of blood-lymph mixing
Lymphatic endothelial cells express podoplanin, a glycoprotein capable of activating platelets through their CLEC-2 receptor, on their surface
[
114
Functional significance of the platelet immune receptors GPVI and CLEC-2
J. Rayes, S. Watson, B. Nieswandt
Journal of Clinical Investigation. 2019, 129, 12-23
]
. Moreover, CLEC-2, combined with GPVI, appears to be important in preventing inflammatory bleeding and maintaining vascular integrity
[
133
Platelets and vascular integrity: how platelets prevent bleeding in inflammation
B. Ho-Tin-Noé, Y. Boulaftali, E. Camerer
Blood. 2018, 131, 277-288
]
.
The intracellular signaling cascade of the CLEC-2 receptor, with the exception of the initial stages of activation, is similar to the intracellular cascade of GPVI activation
[
108,
The N-terminal SH2 domain of Syk is required for (hem)ITAM, but not integrin, signaling in mouse platelets
C. Hughes, B. Finney, F. Koentgen, K. Lowe, S. Watson
Blood. 2015, 125, 144-154
115
GPVI and CLEC-2 in hemostasis and vascular integrity
S. WATSON, J. HERBERT, A. POLLITT
Journal of Thrombosis and Haemostasis. 2010, 8, 1456-1467
]
. Unlike GPVI, the cytoplasmic domain of CLEC-2 contains only one amino acid sequence, YxxL, and also lacks a polyproline-rich region
[
108,
The N-terminal SH2 domain of Syk is required for (hem)ITAM, but not integrin, signaling in mouse platelets
C. Hughes, B. Finney, F. Koentgen, K. Lowe, S. Watson
Blood. 2015, 125, 144-154
134
Syk and Src Family Kinases Regulate C-type Lectin Receptor 2 (CLEC-2)-mediated Clustering of Podoplanin and Platelet Adhesion to Lymphatic Endothelial Cells
A. Pollitt, N. Poulter, E. Gitz, L. Navarro-Nuñez, Y. Wang, C. Hughes, S. Thomas, B. Nieswandt, M. Douglas, D. Owen, D. Jackson, M. Dustin, S. Watson
Journal of Biological Chemistry. 2014, 289, 35695-35710
]
. Thus, the activation of CLEC-2 is even more dependent on the clustering of receptors, as well as on the localization of CLEC-2 in the region rich in other signaling molecules
[
134
Syk and Src Family Kinases Regulate C-type Lectin Receptor 2 (CLEC-2)-mediated Clustering of Podoplanin and Platelet Adhesion to Lymphatic Endothelial Cells
A. Pollitt, N. Poulter, E. Gitz, L. Navarro-Nuñez, Y. Wang, C. Hughes, S. Thomas, B. Nieswandt, M. Douglas, D. Owen, D. Jackson, M. Dustin, S. Watson
Journal of Biological Chemistry. 2014, 289, 35695-35710
]
. Primary phosphorylation of CLEC-2 upon its activation is produced by Syk kinases, which are maintained in an insignificant amount in an active state in resting platelets due to the activity of SFK
[
108
The N-terminal SH2 domain of Syk is required for (hem)ITAM, but not integrin, signaling in mouse platelets
C. Hughes, B. Finney, F. Koentgen, K. Lowe, S. Watson
Blood. 2015, 125, 144-154
]
. Then, inactive Syk is attached to the phosphorylated and clustered CLEC-2, which makes them active and triggers a positive feedback loop (Fig. 3). The production of active Syk, similarly to GPVI, leads to the formation of the LAT signalosome and the activation of PLCg2, which initiates calcium signaling in platelets.
Figure 3. Scheme of tyrosine kinase signaling in platelets (based on the signal transduction network of CLEC-2 receptor). Upon binding of the receptor to the ligand (podoplanin, rhodocytin, or fucoidan), receptor clustering occurs. At the same time, it is believed that receptors are clustered in the region of lipid rafts (membrane microdomains enriched in cholesterol). GPVI and FcRIIA also cluster after ligand binding. In resting platelets, small amounts of SFK are maintained in an active state by phosphatases CD148. Active SFKs can also support small numbers of active Syk. Upon clustering of receptors that trigger the activation of tyrosine kinases, either Syk (CLEC-2) or SFK (GPVI, FcRIIA) phosphorylate their cytoplasmic domains, which leads to increased activation of Syk. Active Syk phosphorylates the adapter protein LAT, to which PI3K binds, becoming active. PI3K phosphorylates PIP2, producing PIP3, which acts as a docking site for Btk tyrosine kinase. When Btk lands on the membrane, it becomes active and phosphorylates PLC2, which also binds to phosphorylated LAT. Active PLC2 hydrolyzes PIP2, producing a secondary activation messenger IP3, which activates the IP3R receptor on the endoplasmic reticulum. The IP3R releases calcium ions from the intracellular platelet stores, which are returned there due to the activity of the SERCA pumps. Calcium ions can also inhibit IP3R. This leads to the initiation of calcium oscillations in the cytosol of platelets.
Adhesion and immune receptors
One of the primary responses of platelets to the damage to the blood vessel walls is their adhesion in the damaged area. The key receptors for the platelet adhesion are glycoprotein Ib (GPIb) and aIIbb3-integrins. Glycoprotein Ib and aIIbb3-integrins do not directly activate tyrosine kinase signaling in platelets: neither GPIb nor aIIbb3-integrins have tyrosine residues, available for phosphorylation, that could serve as activation sites for initiating tyrosine kinase signaling
[
18,
Platelet signaling
Stalker TJ, Newman DK, Ma P, Wannemacher KM, Brass LF
Handbook of Experimental Pharmacology. 2012, None, 59-85
98
Platelet ITAM signaling
W. Bergmeier, L. Stefanini
Current Opinion in Hematology. 2013, 20, 445-450
]
. However, indirectly, through the formation of complexes with other enzymes and with each other, both GPIb and aIIbb3-integrins can significantly contribute to platelet activation, initiating the activation of tyrosine kinases
[
128,
Integrin αIIbβ3. In: Michelson AD, editor. Platelets (Fourth Edition)
Bledzka K, Qin J, Plow EF.
Academic Press. 2019, None, 227–41
135
Platelet GPIb complex as a target for anti-thrombotic drug development
J. Clemetson, K. Clemetson
Thrombosis and Haemostasis. 2008, 99, 473-479
]
. Other important integrins on the platelet surface area integrins αvβ3, αvβ1, and α6β1, which are necessary both for platelet interactions with fibronectin and laminin, as well as for the formation of platelet aggregates with immune cells
[
136
Targeting Integrin and Integrin Signaling in Treating Thrombosis
B. Estevez, B. Shen, X. Du
Arteriosclerosis, Thrombosis, and Vascular Biology. 2015, 35, 24-29
]
.
GPIb is a complex of three glycoproteins (GPIb-GPIX-GPV) that binds to the A2 domain of the flux-unfolded vWF
[
137,
Von Willebrand factor-A1 domain binds platelet glycoprotein Ibα in multiple states with distinctive force-dependent dissociation kinetics
L. Ju, Y. Chen, F. Zhou, H. Lu, M. Cruz, C. Zhu
Thrombosis Research. 2015, 136, 606-612
138
A short history of platelet glycoprotein Ib complex
Clemetson K
Thrombosis and Haemostasis. 2007, 98 (1), 63-8
]
. This leads to the attraction of platelets to the activating surfaces - damaged endothelium or collagen of the subendothelial matrix - and initiates activation, adhesion, and aggregation
[
27
Platelet biology and functions: new concepts and clinical perspectives
P. van der Meijden, J. Heemskerk
Nature Reviews Cardiology. 2019, 16, 166-179
]
. GPIb has been shown to be a mechanosensitive receptor, but the sequence of intracellular events in platelets upon GPIb binding to the ligand is unclear. GPIb forms a complex with the adapter protein 14-3-3x, which also possesses phospholipase activity
[
139
Association of a phospholipase A2 (14-3-3 protein) with the platelet glycoprotein Ib-IX complex
X. Du, S. Harris, T. Tetaz, M. Ginsberg, M. Berndt
Journal of Biological Chemistry. 1994, 269, 18287-18290
]
, as well as filamin A
[
140
The structure of the GPIb–filamin A complex
F. Nakamura, R. Pudas, O. Heikkinen, P. Permi, I. Kilpeläinen, A. Munday, J. Hartwig, T. Stossel, J. Ylänne
Blood. 2006, 107, 1925-1932
]
. These proteins bind GPIb to the actin cytoskeleton and can determine its mechanosensitivity. On the other hand, the relationship between GPIb and 14-3-3x may be important for the activation of GPIb-bound PI3K kinase
[
141,
A functional 14-3-3ζ–independent association of PI3-kinase with glycoprotein Ibα, the major ligand-binding subunit of the platelet glycoprotein Ib-IX-V complex
F. Mu, R. Andrews, J. Arthur, A. Munday, S. Cranmer, S. Jackson, F. Stomski, A. Lopez, M. Berndt
Blood. 2008, 111, 4580-4587
142
Functional association of phosphoinositide-3-kinase with platelet glycoprotein Ibα, the major ligand-binding subunit of the glycoprotein Ib-IX-V complex
F. MU, S. CRANMER, R. ANDREWS, M. BERNDT
Journal of Thrombosis and Haemostasis. 2010, 8, 324-330
]
. It is assumed that activation of GPIb leads to activation of PI3K, which, by producing PIP3, contributes to the activation of Btk tyrosine kinase
[
45,
Impact of the PI3-kinase/Akt pathway on ITAM and hemITAM receptors: Haemostasis, platelet activation and antithrombotic therapy
A. Moroi, S. Watson
Biochemical Pharmacology. 2015, 94, 186-194
142
Functional association of phosphoinositide-3-kinase with platelet glycoprotein Ibα, the major ligand-binding subunit of the glycoprotein Ib-IX-V complex
F. MU, S. CRANMER, R. ANDREWS, M. BERNDT
Journal of Thrombosis and Haemostasis. 2010, 8, 324-330
]
.
Integrin “outside-in” signaling is initiated upon integrin clustering
[
41,
Platelet Signal Transduction. In: Michelson AD, editor. Platelets (Fourth Edition)
Lee RH, Stefanini L, Bergmeier W.
Academic Press. 2019, None, 329-48
95,
Signaling During Platelet Adhesion and Activation
Z. Li, M. Delaney, K. O'Brien, X. Du
Arteriosclerosis, Thrombosis, and Vascular Biology. 2010, 30, 2341-2349
143
Platelet integrin αIIbβ3: signal transduction, regulation, and its therapeutic targeting
J. Huang, X. Li, X. Shi, M. Zhu, J. Wang, S. Huang, X. Huang, H. Wang, L. Li, H. Deng, Y. Zhou, J. Mao, Z. Long, Z. Ma, W. Ye, J. Pan, X. Xi, J. Jin
Journal of Hematology & Oncology. 2019, 12, None
]
. Similar to GPIb, the detailed signaling sequence for this process is currently unknown. It has been shown that the initiation of “outside-in” activation requires the participation of the FcgR chains of the GPVI receptor, as well as the FcgRIIa receptor
[
128,
Integrin αIIbβ3. In: Michelson AD, editor. Platelets (Fourth Edition)
Bledzka K, Qin J, Plow EF.
Academic Press. 2019, None, 227–41
143
Platelet integrin αIIbβ3: signal transduction, regulation, and its therapeutic targeting
J. Huang, X. Li, X. Shi, M. Zhu, J. Wang, S. Huang, X. Huang, H. Wang, L. Li, H. Deng, Y. Zhou, J. Mao, Z. Long, Z. Ma, W. Ye, J. Pan, X. Xi, J. Jin
Journal of Hematology & Oncology. 2019, 12, None
]
. On the other hand, it was suggested that the cytoplasmic domain of αIIbβ3 integrin also contains several tyrosine residues that do not belong to any canonical motifs but can be phosphorylated
[
128
Integrin αIIbβ3. In: Michelson AD, editor. Platelets (Fourth Edition)
Bledzka K, Qin J, Plow EF.
Academic Press. 2019, None, 227–41
]
. Whether they affect, activation is currently unknown. We assume that the following chain of events is most likely: platelets receive a “mechanical” signal from GPIb by interacting with vWF, which attracts them to collagen. The platelets then receive a subsequent signal from the GPVI receptor when they come into contact with collagen
[
19,
Regulation of Platelet Activation and Coagulation and Its Role in Vascular Injury and Arterial Thrombosis
M. Tomaiuolo, L. Brass, T. Stalker
Interventional Cardiology Clinics. 2017, 6, 1-12
95
Signaling During Platelet Adhesion and Activation
Z. Li, M. Delaney, K. O'Brien, X. Du
Arteriosclerosis, Thrombosis, and Vascular Biology. 2010, 30, 2341-2349
]
. This leads to the initiation of tyrosine kinase signaling. Activated GPIb also leads to the activation of associated PI3K, which enhances the activation of tyrosine kinases
[
142
Functional association of phosphoinositide-3-kinase with platelet glycoprotein Ibα, the major ligand-binding subunit of the glycoprotein Ib-IX-V complex
F. MU, S. CRANMER, R. ANDREWS, M. BERNDT
Journal of Thrombosis and Haemostasis. 2010, 8, 324-330
]
. These signals jointly trigger the activation of integrins "inside-out" and then "outside-in", which occurs tyrosine kinase-dependent
[
20,
RAP GTPases and platelet integrin signaling
L. Stefanini, W. Bergmeier
Platelets. 2019, 30, 41-47
98
Platelet ITAM signaling
W. Bergmeier, L. Stefanini
Current Opinion in Hematology. 2013, 20, 445-450
]
. Thus, GPIb and αIIbβ3 induced signaling to become strong positive feedbacks for tyrosine kinase signaling in platelets.
It has been shown that in bacterial sepsis and the generation of an immune response, platelets can surround bacteria that have appeared in the bloodstream, which will lead to the death of bacteria
[
144
The platelet Fc receptor, FcγRIIa
J. Qiao, M. Al-Tamimi, R. Baker, R. Andrews, E. Gardiner
Immunological Reviews. 2015, 268, 241-252
]
. FcγRIIa is the key immune receptor of the platelets
[
98,
Platelet ITAM signaling
W. Bergmeier, L. Stefanini
Current Opinion in Hematology. 2013, 20, 445-450
114
Functional significance of the platelet immune receptors GPVI and CLEC-2
J. Rayes, S. Watson, B. Nieswandt
Journal of Clinical Investigation. 2019, 129, 12-23
]
. The key function of this receptor is to recognize the constant amino acid sequence of IgG opsonizing antigens. Single IgGs are not capable of platelet activation via FcγRIIa
[
114,
Functional significance of the platelet immune receptors GPVI and CLEC-2
J. Rayes, S. Watson, B. Nieswandt
Journal of Clinical Investigation. 2019, 129, 12-23
144
The platelet Fc receptor, FcγRIIa
J. Qiao, M. Al-Tamimi, R. Baker, R. Andrews, E. Gardiner
Immunological Reviews. 2015, 268, 241-252
]
. Thus, like GPVI and CLEC-2, FcγRIIa requires clustering for sufficient activation.
Among the receptors that induce platelet activation, a group of receptors that recognize pathogen-associated molecular patterns (PAMP) and molecular patterns associated with damage (DAMP) - Tall-like receptors (TLR) – stands out
[
145,
Platelet Toll-like receptor expression and activation induced by lipopolysaccharide and sepsis
T. Claushuis, A. Van Der Veen, J. Horn, M. Schultz, R. Houtkooper, C. Van ’T Veer, T. Van Der Poll
Platelets. 2019, 30, 296-304
146
Platelet Toll-Like Receptors Mediate Thromboinflammatory Responses in Patients With Essential Thrombocythemia
C. Marín Oyarzún, A. Glembotsky, N. Goette, P. Lev, G. De Luca, M. Baroni Pietto, B. Moiraghi, M. Castro Ríos, A. Vicente, R. Marta, M. Schattner, P. Heller
Frontiers in Immunology. 2020, 11, None
]
. The main effector of TLR receptors in nuclear cells is the NFᴂB transcription factor, which triggers gene transcription and de novo protein synthesis in response to activation, which is not applicable to platelets
[
147
The inflammatory role of platelets via their TLRs and Siglec receptors
F. Cognasse
Frontiers in Immunology. 2015, 6, None
]
.
Activation of TLR receptors initiates the assembly of a signaling complex based on the adapter protein MyD88 — the middosome
[
148
Моделирование секреции гранул при активации тромбоцитов через TLR4-рецептор
Майоров А.С., Шепелюк Т.О., Балабин Ф.А., Мартьянов А.А., Нечипуренко Д.Ю., Свешникова А.Н.
Биофизика. 2018, 63 (3), 475-483
]
. The middosome also consists of the TIRAP adapter, which leads to IKkb activation, as well as the NFᴂB transcription factor
[
145,
Platelet Toll-like receptor expression and activation induced by lipopolysaccharide and sepsis
T. Claushuis, A. Van Der Veen, J. Horn, M. Schultz, R. Houtkooper, C. Van ’T Veer, T. Van Der Poll
Platelets. 2019, 30, 296-304
147
The inflammatory role of platelets via their TLRs and Siglec receptors
F. Cognasse
Frontiers in Immunology. 2015, 6, None
]
. On the other hand, the formation of the middosome complex also leads to the activation of soluble guanylate cyclase, which triggers the production of cGMP, as well as the activation of protein kinase G and further inhibitory signaling
[
147
The inflammatory role of platelets via their TLRs and Siglec receptors
F. Cognasse
Frontiers in Immunology. 2015, 6, None
]
. Finally, the middosome complex also includes the IRAK1, IRAK4, and TRAF6 adapters. PI3K is attached to TRAF-6 in the middosome complex, which leads to the activation of Akt and eNOS, which synthesizes NO, which also leads to the activation of guanylate cyclase, the production of cGMP, and the activation of PKG
[
149
Akt signaling in platelets and thrombosis
D. Woulfe
Expert Review of Hematology. 2010, 3, 81-91
]
. It has been shown that activation of IKkb leads to the activation of SNAP23, one of the key proteins required for platelet degranulation
[
150
IκB kinase phosphorylation of SNAP-23 controls platelet secretion
Z. Karim, J. Zhang, M. Banerjee, M. Chicka, R. Al Hawas, T. Hamilton, P. Roche, S. Whiteheart
Blood. 2013, 121, 4567-4574
]
. Thus, TLR-induced signaling can potentially lead to both platelet activation and platelet inhibition.
From the TLR family, the expression of TLR2 receptors on platelets has been unambiguously demonstrated both at the mRNA and at the protein level
[
151
Platelet Toll-like receptor (TLR) expression and TLR-mediated platelet activation in acute myocardial infarction
K. Hally, A. La Flamme, P. Larsen, S. Harding
Thrombosis Research. 2017, 158, 8-15
]
. TLR-2 is a receptor that recognizes peptidoglycan sequences of gram-positive bacteria
[
151
Platelet Toll-like receptor (TLR) expression and TLR-mediated platelet activation in acute myocardial infarction
K. Hally, A. La Flamme, P. Larsen, S. Harding
Thrombosis Research. 2017, 158, 8-15
]
. Stimulation by two typical periodontopathogens (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans) caused the formation of heteroaggregates of platelets and neutrophils
[
152,
Efficient phagocytosis of periodontopathogens by neutrophils requires plasma factors, platelets and TLR2
A. ASSINGER, M. LAKY, G. SCHABBAUER, A. HIRSCHL, E. BUCHBERGER, B. BINDER, I. VOLF
Journal of Thrombosis and Haemostasis. 2011, 9, 799-809
153
Stimulation of Toll-Like Receptor 2 in Human Platelets Induces a Thromboinflammatory Response Through Activation of Phosphoinositide 3-Kinase
P. Blair, S. Rex, O. Vitseva, L. Beaulieu, K. Tanriverdi, S. Chakrabarti, C. Hayashi, C. Genco, M. Iafrati, J. Freedman
Circulation Research. 2009, 104, 346-354
]
, and this significantly enhanced the elimination of bacteria by neutrophils
[
152
Efficient phagocytosis of periodontopathogens by neutrophils requires plasma factors, platelets and TLR2
A. ASSINGER, M. LAKY, G. SCHABBAUER, A. HIRSCHL, E. BUCHBERGER, B. BINDER, I. VOLF
Journal of Thrombosis and Haemostasis. 2011, 9, 799-809
]
. In this case, the formation of heteroaggregates was significantly reduced upon inhibition of TLR2
[
152
Efficient phagocytosis of periodontopathogens by neutrophils requires plasma factors, platelets and TLR2
A. ASSINGER, M. LAKY, G. SCHABBAUER, A. HIRSCHL, E. BUCHBERGER, B. BINDER, I. VOLF
Journal of Thrombosis and Haemostasis. 2011, 9, 799-809
]
.
The platelet surface also contains a sufficient amount of the TLR4 receptor, which recognizes the components of the cell wall of gram-negative bacteria - lipopolysaccharides (LPS)
[
145
Platelet Toll-like receptor expression and activation induced by lipopolysaccharide and sepsis
T. Claushuis, A. Van Der Veen, J. Horn, M. Schultz, R. Houtkooper, C. Van ’T Veer, T. Van Der Poll
Platelets. 2019, 30, 296-304
]
. However, incubation of LPS with platelets is more likely to have an inhibitory effect
[
50
Effects of bacterial lipopolysaccharides on platelet function: inhibition of weak platelet activation
A. Martyanov, A. Maiorov, A. Filkova, A. Ryabykh, G. Svidelskaya, E. Artemenko, S. Gambaryan, M. Panteleev, A. Sveshnikova
Scientific Reports. 2020, 10, None
]
. Like TLR2, TLR4 may be of great importance primarily in immune rather than thrombotic responses. For example, it has been shown that the stimulation of platelets by LPS can induce the synthesis of inflammatory mediators in them, including IL-1β
[
9
Lipopolysaccharide Signaling without a Nucleus: Kinase Cascades Stimulate Platelet Shedding of Proinflammatory IL-1β–Rich Microparticles
G. Brown, T. McIntyre
The Journal of Immunology. 2011, 186, 5489-5496
]
, sCD40L
[
154
Periodontopathogens induce expression of CD40L on human platelets via TLR2 and TLR4
A. Assinger, M. Laky, S. Badrnya, A. Esfandeyari, I. Volf
Thrombosis Research. 2012, 130, e73-e78
]
, RANTES
[
155
The Role of Human Platelet Preparation for Toll-Like Receptors 2 and 4 Related Platelet Responsiveness
J. Koessler, M. Niklaus, K. Weber, A. Koessler, S. Kuhn, M. Boeck, A. Kobsar
TH Open. 2019, 03, e94-e102
]
. It has also been shown that LPS can enhance the production of eicosanoids and markers of oxidative stress
[
156
Lipopolysaccharide as trigger of platelet aggregation via eicosanoid over-production
C. Nocella, R. Carnevale, S. Bartimoccia, M. Novo, R. Cangemi, D. Pastori, C. Calvieri, P. Pignatelli, F. Violi
Thrombosis and Haemostasis. 2017, 117, 1558-1570
]
.
TLR7 is expressed in platelets both at the protein and mRNA levels
[
151
Platelet Toll-like receptor (TLR) expression and TLR-mediated platelet activation in acute myocardial infarction
K. Hally, A. La Flamme, P. Larsen, S. Harding
Thrombosis Research. 2017, 158, 8-15
]
. Recent data have demonstrated the potential role of platelet TLR7 in response to influenza virus
[
157
The role of platelets in mediating a response to human influenza infection
M. Koupenova, H. Corkrey, O. Vitseva, G. Manni, C. Pang, L. Clancy, C. Yao, J. Rade, D. Levy, J. Wang, R. Finberg, E. Kurt-Jones, J. Freedman
Nature Communications. 2019, 10, None
]
, consisting in endocytosis of virions, formation of platelet-neutrophil heteroaggregates, and subsequent activation of neutrophils due to increased expression of CD62P and CD40L on platelets
[
157,
The role of platelets in mediating a response to human influenza infection
M. Koupenova, H. Corkrey, O. Vitseva, G. Manni, C. Pang, L. Clancy, C. Yao, J. Rade, D. Levy, J. Wang, R. Finberg, E. Kurt-Jones, J. Freedman
Nature Communications. 2019, 10, None
158
Revisiting Platelets and Toll-Like Receptors (TLRs): At the Interface of Vascular Immunity and Thrombosis
K. Hally, S. Fauteux-Daniel, H. Hamzeh-Cognasse, P. Larsen, F. Cognasse
International Journal of Molecular Sciences. 2020, 21, 6150
]
. Functional TLR9 is also present on platelets, while TLR9 is localized in the near-membrane regions, being enclosed in vesicles
[
159
T granules in human platelets function in TLR9 organization and signaling
J. Thon, C. Peters, K. Machlus, R. Aslam, J. Rowley, H. Macleod, M. Devine, T. Fuchs, A. Weyrich, J. Semple, R. Flaumenhaft, J. Italiano
Journal of Cell Biology. 2012, 198, 561-574
]
. It has been shown that stimulation by a number of thrombotic agonists leads to the movement of TLR9 from intracellular vesicles to the membrane using vesicle-associated membrane proteins VAMP7 and VAMP8. The expression of TLR9 on the platelet surface enhances the uptake and endocytosis of DNA, the TLR9 ligand
[
159
T granules in human platelets function in TLR9 organization and signaling
J. Thon, C. Peters, K. Machlus, R. Aslam, J. Rowley, H. Macleod, M. Devine, T. Fuchs, A. Weyrich, J. Semple, R. Flaumenhaft, J. Italiano
Journal of Cell Biology. 2012, 198, 561-574
]
. It has also been shown that carboxy (alkylpyrrole) protein adducts (CAPs), lipid oxidation end products, are another ligand for platelet TLR9
[
160
Engagement of Platelet Toll-Like Receptor 9 by Novel Endogenous Ligands Promotes Platelet Hyperreactivity and Thrombosis
S. Panigrahi, Y. Ma, L. Hong, D. Gao, X. West, R. Salomon, T. Byzova, E. Podrez
Circulation Research. 2013, 112, 103-112
]
, causing integrin activation and a granule secretion.
In addition to PAMP-induced signaling, platelets can also be a source of DAMP, which will be recognized by TLR receptors. Thus, endogenous mitochondrial DAMPs, mitochondrial DNA (mtDNA), and mitochondrial proteins are powerful immunostimulants
[
161
Mitochondria in lung biology and pathology: more than just a powerhouse
P. Schumacker, M. Gillespie, K. Nakahira, A. Choi, E. Crouser, C. Piantadosi, J. Bhattacharya
American Journal of Physiology-Lung Cellular and Molecular Physiology. 2014, 306, L962-L974
]
. The structure and proinflammatory effects of mtDNA are similar, if not identical, to bacterial DNA due to its proteobacterial origin. This similarity extends to the ability of mtDNA to stimulate TLR9 due to the presence of unmethylated CpG dinucleotides in mtDNA
[
162,
MITOCHONDRIAL DNA IS RELEASED BY SHOCK AND ACTIVATES NEUTROPHILS VIA P38 MAP KINASE
Q. Zhang, K. Itagaki, C. Hauser
Shock. 2010, 34, 55-59
163
Circulating mitochondrial DAMPs cause inflammatory responses to injury
Q. Zhang, M. Raoof, Y. Chen, Y. Sumi, T. Sursal, W. Junger, K. Brohi, K. Itagaki, C. Hauser
Nature. 2010, 464, 104-107
]
. mtDNA can stimulate neutrophils and induce NETosis
[
164
Platelets release mitochondria serving as substrate for bactericidal group IIA-secreted phospholipase A2 to promote inflammation
L. Boudreau, A. Duchez, N. Cloutier, D. Soulet, N. Martin, J. Bollinger, A. Paré, M. Rousseau, G. Naika, T. Lévesque, C. Laflamme, G. Marcoux, G. Lambeau, R. Farndale, M. Pouliot, H. Hamzeh-Cognasse, F. Cognasse, O. Garraud, P. Nigrovic, H. Guderley, S. Lacroix, L. Thibault, J. Semple, M. Gelb, E. Boilard
Blood. 2014, 124, 2173-2183
]
. mtDNA can also induce endothelial cell permeability, thereby facilitating the transmission of a localized immunogenic response to distal organs
[
165
Mitochondrial DAMPs Increase Endothelial Permeability through Neutrophil Dependent and Independent Pathways
S. Sun, T. Sursal, Y. Adibnia, C. Zhao, Y. Zheng, H. Li, L. Otterbein, C. Hauser, K. Itagaki
PLoS ONE. 2013, 8, e59989
]
.
HMGB1 is another well-studied DAMP that is passively released during both cellular stress and necrosis: HMGB1 paracrine signals “danger” to neighboring cells. It has been shown that HMGB1 binds to several members of the TLR family: HMGB1 can form a complex with CpG-DNA and bind to TLR9 and RAGE, increasing cytokine production in plasma dendritic cells
[
166
Toll-like receptor 9–dependent activation by DNA-containing immune complexes is mediated by HMGB1 and RAGE
J. Tian, A. Avalos, S. Mao, B. Chen, K. Senthil, H. Wu, P. Parroche, S. Drabic, D. Golenbock, C. Sirois, J. Hua, L. An, L. Audoly, G. La Rosa, A. Bierhaus, P. Naworth, A. Marshak-Rothstein, M. Crow, K. Fitzgerald, E. Latz, P. Kiener, A. Coyle
Nature Immunology. 2007, 8, 487-496
]
. When HMGB1 binds to nucleosomes, macrophages and dendritic cells are activated via TLR2
[
167
Induction of inflammatory and immune responses by HMGB1–nucleosome complexes: implications for the pathogenesis of SLE
V. Urbonaviciute, B. Fürnrohr, S. Meister, L. Munoz, P. Heyder, F. De Marchis, M. Bianchi, C. Kirschning, H. Wagner, A. Manfredi, J. Kalden, G. Schett, P. Rovere-Querini, M. Herrmann, R. Voll
Journal of Experimental Medicine. 2008, 205, 3007-3018
]
.
Finally, platelets also contain receptors for the components of the complement system: C3aR, C5aR. It has been shown that upon their activation, the secretion of platelet granules and the exposure of P-selectin occur, which also attracts immune cells. Also, during the secretion of granules, the C1qR receptor is exposed. It has been shown that in patients with the coronary syndrome, the expression of these receptors on the platelet surface is increased
[
168
Platelets and Complement Cross-Talk in Early Atherogenesis
H. Kim, E. Conway
Frontiers in Cardiovascular Medicine. 2019, 6, None
]
.
Inhibition of platelet activation
The platelet is maintained in an inactivated state by high concentrations of cyclic nucleotides. An increase in cAMP concentration stimulates the prostacyclin receptor, IP, associated with Gs proteins
[
169
Vasodilator-Stimulated Phosphoprotein (VASP)-dependent and -independent pathways regulate thrombin-induced activation of Rap1b in platelets
P. Benz, H. Laban, J. Zink, L. Günther, U. Walter, S. Gambaryan, K. Dib
Cell Communication and Signaling. 2016, 14, None
]
. In addition to prostacyclin, there are also receptors for prostaglandin E2 (PGE2) on the platelet surface: EP3, which causes a decrease in the concentration of cAMP in a Gi-dependent manner, and EP4, on the contrary, increases the concentration of cAMP in platelets in a Gs-dependent manner
[
170
PGE1 and PGE2 modify platelet function through different prostanoid receptors
D. Iyú, M. Jüttner, J. Glenn, A. White, A. Johnson, S. Fox, S. Heptinstall
Prostaglandins & Other Lipid Mediators. 2011, 94, 9-16
]
. The increase in the concentration of cGMP occurs under the action of nitric oxide (NO) synthesized by healthy endothelium
[
52,
A review and discussion of platelet nitric oxide and nitric oxide synthase: do blood platelets produce nitric oxide from l-arginine or nitrite?
S. Gambaryan, D. Tsikas
Amino Acids. 2015, 47, 1779-1793
171
Endothelial Function and Dysfunction
J. Deanfield, J. Halcox, T. Rabelink
Circulation. 2007, 115, 1285-1295
]
. Also, NO can be synthesized by platelet NO synthases NOS2 and NOS3
[
172
Platelet-Derived Nitric Oxide Signaling and Regulation
E. Gkaliagkousi, J. Ritter, A. Ferro
Circulation Research. 2007, 101, 654-662
]
. In platelets, NO stimulates the soluble guanylate cyclase sGC, which increases the synthesis of cGMP from GTP. An increase in the level of activity of soluble GC (sGC) leads to a decrease in the level of intracellular calcium
[
50,
Effects of bacterial lipopolysaccharides on platelet function: inhibition of weak platelet activation
A. Martyanov, A. Maiorov, A. Filkova, A. Ryabykh, G. Svidelskaya, E. Artemenko, S. Gambaryan, M. Panteleev, A. Sveshnikova
Scientific Reports. 2020, 10, None
173
Nitric oxide specifically inhibits integrin-mediated platelet adhesion and spreading on collagen
W. ROBERTS, R. RIBA, S. HOMER-VANNIASINKAM, R. FARNDALE, K. NASEEM
Journal of Thrombosis and Haemostasis. 2008, 6, 2175-2185
]
. Also, NO is able to catalyze the phosphorylation of TxA2 receptors, thereby preventing the activation of TxA2 platelets
[
173
Nitric oxide specifically inhibits integrin-mediated platelet adhesion and spreading on collagen
W. ROBERTS, R. RIBA, S. HOMER-VANNIASINKAM, R. FARNDALE, K. NASEEM
Journal of Thrombosis and Haemostasis. 2008, 6, 2175-2185
]
. In addition, it has recently been shown that NO also affects the activation of integrins α2β1 and aIIbb3
[
173
Nitric oxide specifically inhibits integrin-mediated platelet adhesion and spreading on collagen
W. ROBERTS, R. RIBA, S. HOMER-VANNIASINKAM, R. FARNDALE, K. NASEEM
Journal of Thrombosis and Haemostasis. 2008, 6, 2175-2185
]
. Although NO has an inhibitory effect on platelet aggregation at high concentrations, it rather stimulates granule secretion by acting through the cGMP pathway at low concentrations (biphasic effect) in vivo
[
173,
Nitric oxide specifically inhibits integrin-mediated platelet adhesion and spreading on collagen
W. ROBERTS, R. RIBA, S. HOMER-VANNIASINKAM, R. FARNDALE, K. NASEEM
Journal of Thrombosis and Haemostasis. 2008, 6, 2175-2185
]
.
Conclusions
Platelet functioning is inextricably associated with the need to simultaneously receive and interpret a large number of external signals. Moreover, in some cases, these signals may contradict each other. Thanks to a complex and accurate network of receptors that trigger GPCR or tyrosine kinase signaling, platelets can “cope with such pressure” and adequately respond to arising breaches of the integrity of blood vessels. Moreover, signaling pathways in platelets can synergistically enhance each other (tyrosine kinase and GPCR) or, conversely, suppress (cAMP / cGMP signaling). Interestingly, platelets also contain voltage-gated receptors, such as the Kv1.3 and APMPA channels
[
175
The unique contribution of ion channels to platelet and megakaryocyte function
M. MAHAUT-SMITH
Journal of Thrombosis and Haemostasis. 2012, 10, 1722-1732
]
. For such a unique cell as a platelet, such a set of receptors becomes fundamentally important since platelets can have a minimal impact on their protein composition during the life cycle.
It is noteworthy that synergistic enhancement of platelet activation pathways can occur both within the same type of signaling and for different types. So, on the one hand, ADP induces calcium signaling and activation of platelet integrins aIIbb3 in a Gq-dependent manner through the P2Y1 receptor. On the other hand, ADP can also reduce the concentration of cAMP in a Gi-dependent manner through the P2Y12 receptor, which greatly enhances platelet activation. On the other hand, the tyrosine kinase signaling branch and GPCR signaling can amplify each other: both of these signaling branches induce the activation of PI3K, which triggers the phosphoinositide signaling branch. Moreover, activation of phosphoinositide signaling during outside-in signaling via platelet integrins aIIbb3 also becomes an important element of synergistic enhancement of platelet activation.
The interplay between the intracellular signaling pathways in platelets also allows them to be activated momentarily: platelets often become the first line of the body's response to pathology. Moreover, platelets are also important participants in immune processes, such as the body's response to a bacterial or viral infection, or to modulate the responses of components of cellular immunity. Secondary messengers that drive all of these platelet responses and provide interactions between activation signals and platelet functional responses will be the subject of the next part of our review series.
Author Contributions
A.A.M. drew the figures, wrote the text, and edited the paper; M.A.P. supervised the project, wrote the text and edited the paper. All authors have read and agreed to the published version of the manuscript.
Conflicts of Interest
The authors declare no conflict of interest
Funding
The project was supported by the Russian Presidential Scholarship SP 2675.2019.4
References of this article:
Hemostasis and thrombosis beyond biochemistry: roles of geometry, flow and diffusion
M. Panteleev, N. Dashkevich, F. Ataullakhanov
Thrombosis Research. 2015, 136, 699-711
Novel mouse hemostasis model for real-time determination of bleeding time and hemostatic plug composition
T. Getz, R. Piatt, B. Petrich, D. Monroe, N. Mackman, W. Bergmeier
Journal of Thrombosis and Haemostasis. 2015, 13, 417-425
Platelets and vascular integrity
C. Deppermann
Platelets. 2018, 29, 549-555
Physiological and pathophysiological aspects of blood platelet activation through CLEC-2 receptor
A. Martyanov, V. Kaneva, M. Panteleev, A. Sveshnikova
Oncohematology. 2018, 13, 83-90
How platelets safeguard vascular integrity
B. HO-TIN-NOÉ, M. DEMERS, D. WAGNER
Journal of Thrombosis and Haemostasis. 2011, 9, 56-65
Platelet ITAM signaling is critical for vascular integrity in inflammation
Yacine Boulaftali, Paul R. Hess, Todd M. Getz, Agnieszka Cholka, Moritz Stolla, Nigel Mackman, A. Phillip Owens III, Jerry Ware, Mark L. Kahn, Wolfgang Bergmeier
The Journal of Clinical Investigation. 2013, 123 (2), 908-916
Editorial: Platelets and Immune Responses During Thromboinflammation
M. Schattner, C. Jenne, S. Negrotto, B. Ho-Tin-Noe
Frontiers in Immunology. 2020, 11,
The dual role of platelet-innate immune cell interactions in thrombo-inflammation
J. Rayes, J. Bourne, A. Brill, S. Watson
Research and Practice in Thrombosis and Haemostasis. 2020, 4, 23-35
Lipopolysaccharide Signaling without a Nucleus: Kinase Cascades Stimulate Platelet Shedding of Proinflammatory IL-1β–Rich Microparticles
G. Brown, T. McIntyre
The Journal of Immunology. 2011, 186, 5489-5496
Platelet functional responses and signalling: the molecular relationship. Part 1: responses.
A. Sveshnikova, M. Stepanyan, M. Panteleev
Systems Biology and Physiology Reports. 2021, 1, 20-28
Platelets: production, morphology and ultrastructure
Thon JN, Italiano JE
Handbook of Experimental Pharmacology. 2012, , 3-22
Platelet shape change and spreading
Aslan JE, Itakura A, Gertz JM, McCarty OJT
Methods in Molecular Biology. 2012, 788, 91-100
Tubulin in Platelets: When the Shape Matters
E. Cuenca-Zamora, F. Ferrer-Marín, J. Rivera, R. Teruel-Montoya
International Journal of Molecular Sciences. 2019, 20, 3484
New explanations for old observations: marginal band coiling during platelet activation
K. Sadoul
Journal of Thrombosis and Haemostasis. 2015, 13, 333-346
Actin dynamics in platelets
Bearer EL, Prakash JM, Li Z.
International Review of Cytology. 2002, 217, 137-82
Platelet Shape Changes and Cytoskeleton Dynamics as Novel Therapeutic Targets for Anti-Thrombotic Drugs
E. Shin, H. Park, J. Noh, K. Lim, J. Chung
Biomolecules & Therapeutics. 2017, 25, 223-230
The first comprehensive and quantitative analysis of human platelet protein composition allows the comparative analysis of structural and functional pathways
J. Burkhart, M. Vaudel, S. Gambaryan, S. Radau, U. Walter, L. Martens, J. Geiger, A. Sickmann, R. Zahedi
Blood. 2012, 120, e73-e82
Platelet signaling
Stalker TJ, Newman DK, Ma P, Wannemacher KM, Brass LF
Handbook of Experimental Pharmacology. 2012, , 59-85
Regulation of Platelet Activation and Coagulation and Its Role in Vascular Injury and Arterial Thrombosis
M. Tomaiuolo, L. Brass, T. Stalker
Interventional Cardiology Clinics. 2017, 6, 1-12
RAP GTPases and platelet integrin signaling
L. Stefanini, W. Bergmeier
Platelets. 2019, 30, 41-47
Platelet Secretion. In: Michelson AD, editor. Platelets (Fourth Edition)
Flaumenhaft R, Sharda A
Academic Press. 2019, , 349-70
Sorting machineries: how platelet-dense granules differ from α-granules
Y. Chen, Y. Yuan, W. Li
Bioscience Reports. 2018, 38,
Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling
A. Sveshnikova, A. Balatskiy, A. Demianova, T. Shepelyuk, S. Shakhidzhanov, M. Balatskaya, A. Pichugin, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 2045-2057
Procoagulant Platelets Form an α-Granule Protein-covered “Cap” on Their Surface That Promotes Their Attachment to Aggregates
A. Abaeva, M. Canault, Y. Kotova, S. Obydennyy, A. Yakimenko, N. Podoplelova, V. Kolyadko, H. Chambost, A. Mazurov, F. Ataullakhanov, A. Nurden, M. Alessi, M. Panteleev
Journal of Biological Chemistry. 2013, 288, 29621-29632
Regulating thrombus growth and stability to achieve an optimal response to injury
L. BRASS, K. WANNEMACHER, P. MA, T. STALKER
Journal of Thrombosis and Haemostasis. 2011, 9, 66-75
Clot Contraction Drives the Translocation of Procoagulant Platelets to Thrombus Surface
D. Nechipurenko, N. Receveur, A. Yakimenko, T. Shepelyuk, A. Yakusheva, R. Kerimov, S. Obydennyy, A. Eckly, C. Léon, C. Gachet, E. Grishchuk, F. Ataullakhanov, P. Mangin, M. Panteleev
Arteriosclerosis, Thrombosis, and Vascular Biology. 2019, 39, 37-47
Platelet biology and functions: new concepts and clinical perspectives
P. van der Meijden, J. Heemskerk
Nature Reviews Cardiology. 2019, 16, 166-179
Computational biology analysis of platelet signaling reveals roles of feedbacks through phospholipase C and inositol 1,4,5-trisphosphate 3-kinase in controlling amplitude and duration of calcium oscillations
F. Balabin, A. Sveshnikova
Mathematical Biosciences. 2016, 276, 67-74
Dynamics of calcium spiking, mitochondrial collapse and phosphatidylserine exposure in platelet subpopulations during activation
S. Obydennyy, A. Sveshnikova, F. Ataullakhanov, M. Panteleev
Journal of Thrombosis and Haemostasis. 2016, 14, 1867-1881
Control of Platelet CLEC-2-Mediated Activation by Receptor Clustering and Tyrosine Kinase Signaling
A. Martyanov, F. Balabin, J. Dunster, M. Panteleev, J. Gibbins, A. Sveshnikova
Biophysical Journal. 2020, 118, 2641-2655
Compartmentalized calcium signaling triggers subpopulation formation upon platelet activation through PAR1
A. Sveshnikova, F. Ataullakhanov, M. Panteleev
Molecular BioSystems. 2015, 11, 1052-1060
Calcium signaling in platelets
D. VARGA-SZABO, A. BRAUN, B. NIESWANDT
Journal of Thrombosis and Haemostasis. 2009, 7, 1057-1066
Agonist-evoked inositol trisphosphate receptor (IP3R) clustering is not dependent on changes in the structure of the endoplasmic reticulum
M. Chalmers, M. Schell, P. Thorn
Biochemical Journal. 2006, 394, 57-66
Mechanisms of increased mitochondria-dependent necrosis in Wiskott-Aldrich syndrome platelets
S. Obydennyi, E. Artemenko, A. Sveshnikova, A. Ignatova, T. Varlamova, S. Gambaryan, G. Lomakina, N. Ugarova, I. Kireev, F. Ataullakhanov, G. Novichkova, A. Maschan, A. Shcherbina, M. Panteleev
Haematologica. 2020, 105, 1095-1106
Platelet subpopulations remain despite strong dual agonist stimulation and can be characterised using a novel six-colour flow cytometry protocol
A. Södergren, S. Ramström
Scientific Reports. 2018, 8,
Программируемая клеточная смерть и функциональная активность тромбоцитов при онкогематологических заболеваниях
А. Мартьянов, А. Игнатова, Г. Свидельская, Е. Пономаренко, С. Гамбарян, А. Свешникова, М. Пантелеев
Биохимия. 2020, 85, 1489-1499
Expression, Purification, and Regulation of Two Isoforms of the Inositol 1,4,5-Trisphosphate 3-Kinase
P. Woodring, J. Garrison
Journal of Biological Chemistry. 1997, 272, 30447-30454
Glutamate regulation of calcium and IP3 oscillating and pulsating dynamics in astrocytes
M. De Pittà, M. Goldberg, V. Volman, H. Berry, E. Ben-Jacob
Journal of Biological Physics. 2009, 35, 383-411
Inositol 1,4,5-trisphosphate 3-kinases: functions and regulations
H. XIA, G. YANG
Cell Research. 2005, 15, 83-91
Regulation of platelet plug formation by phosphoinositide metabolism
S. Min, C. Abrams
Blood. 2013, 122, 1358-1365
Platelet Signal Transduction. In: Michelson AD, editor. Platelets (Fourth Edition)
Lee RH, Stefanini L, Bergmeier W.
Academic Press. 2019, , 329-48
Recruitment and regulation of phosphatidylinositol phosphate kinase type 1γ by the FERM domain of talin
G. Di Paolo, L. Pellegrini, K. Letinic, G. Cestra, R. Zoncu, S. Voronov, S. Chang, J. Guo, M. Wenk, P. De Camilli
Nature. 2002, 420, 85-89
Platelets lacking PIP5KIγ have normal integrin activation but impaired cytoskeletal-membrane integrity and adhesion
Y. Wang, L. Zhao, A. Suzuki, L. Lian, S. Min, Z. Wang, R. Litvinov, T. Stalker, T. Yago, A. Klopocki, D. Schmidtke, H. Yin, J. Choi, R. McEver, J. Weisel, J. Hartwig, C. Abrams
Blood. 2013, 121, 2743-2752
The role of class I, II and III PI 3-kinases in platelet production and activation and their implication in thrombosis
C. Valet, S. Severin, G. Chicanne, P. Laurent, F. Gaits-Iacovoni, M. Gratacap, B. Payrastre
Advances in Biological Regulation. 2016, 61, 33-41
Impact of the PI3-kinase/Akt pathway on ITAM and hemITAM receptors: Haemostasis, platelet activation and antithrombotic therapy
A. Moroi, S. Watson
Biochemical Pharmacology. 2015, 94, 186-194
Structure and lipid-binding properties of the kindlin-3 pleckstrin homology domain
T. Ni, A. Kalli, F. Naughton, L. Yates, O. Naneh, M. Kozorog, G. Anderluh, M. Sansom, R. Gilbert
Biochemical Journal. 2017, 474, 539-556
Different roles of SHIP1 according to the cell context: The example of blood platelets
M. Gratacap, S. Séverin, G. Chicanne, M. Plantavid, B. Payrastre
Advances in Enzyme Regulation. 2008, 48, 240-252
SH2-containing inositol 5-phosphatases 1 and 2 in blood platelets: their interactions and roles in the control of phosphatidylinositol 3,4,5-trisphosphate levels
S. GIURIATO, X. PESESSE, S. BODIN, T. SASAKI, C. VIALA, E. MARION, J. PENNINGER, S. SCHURMANS, C. ERNEUX, B. PAYRASTRE
Biochemical Journal. 2003, 376, 199-207
Deficiency of Src homology 2 domain–containing inositol 5-phosphatase 1 affects platelet responses and thrombus growth
S. Séverin, M. Gratacap, N. Lenain, L. Alvarez, E. Hollande, J. Penninger, C. Gachet, M. Plantavid, B. Payrastre
Journal of Clinical Investigation. 2007, 117, 944-952
Effects of bacterial lipopolysaccharides on platelet function: inhibition of weak platelet activation
A. Martyanov, A. Maiorov, A. Filkova, A. Ryabykh, G. Svidelskaya, E. Artemenko, S. Gambaryan, M. Panteleev, A. Sveshnikova
Scientific Reports. 2020, 10,
GMP and cGMP-dependent protein kinase in platelets and blood cells
Walter U, Gambaryan S
Handbook of Experimental Pharmacology. 2009, , 533-48
A review and discussion of platelet nitric oxide and nitric oxide synthase: do blood platelets produce nitric oxide from l-arginine or nitrite?
S. Gambaryan, D. Tsikas
Amino Acids. 2015, 47, 1779-1793
A Boolean view separates platelet activatory and inhibitory signalling as verified by phosphorylation monitoring including threshold behaviour and integrin modulation
M. Mischnik, D. Boyanova, K. Hubertus, J. Geiger, N. Philippi, M. Dittrich, G. Wangorsch, J. Timmer, T. Dandekar
Molecular BioSystems. 2013, 9, 1326
Activation of Platelet Function Through G Protein–Coupled Receptors
S. Offermanns
Circulation Research. 2006, 99, 1293-1304
Kinetic diversity in G-protein-coupled receptor signalling
V. Katanaev, M. Chornomorets
Biochemical Journal. 2007, 401, 485-495
Synergistic Activation of Phospholipase C-β3 by Gαq and Gβγ Describes a Simple Two-State Coincidence Detector
F. Philip, G. Kadamur, R. Silos, J. Woodson, E. Ross
Current Biology. 2010, 20, 1327-1335
A quantitative characterization of the yeast heterotrimeric G protein cycle
T. Yi, H. Kitano, M. Simon
Proceedings of the National Academy of Sciences. 2003, 100, 10764-10769
Receptor-Mediated Activation of Heterotrimeric G-Proteins in Living Cells
C. Janetopoulos
Science. 2001, 291, 2408-2411
A Direct and Functional Interaction Between Go and Rab5 During G Protein-Coupled Receptor Signaling
V. Purvanov, A. Koval, V. Katanaev
Science Signaling. 2010, 3, ra65-ra65
Double Suppression of the Gα Protein Activity by RGS Proteins
C. Lin, A. Koval, S. Tishchenko, A. Gabdulkhakov, U. Tin, G. Solis, V. Katanaev
Molecular Cell. 2014, 53, 663-671
High capacity in G protein-coupled receptor signaling
A. Keshelava, G. Solis, M. Hersch, A. Koval, M. Kryuchkov, S. Bergmann, V. Katanaev
Nature Communications. 2018, 9,
G PROTEIN βγ SUBUNITS
D. Clapham, E. Neer
Annual Review of Pharmacology and Toxicology. 1997, 37, 167-203
Biochemical and pharmacological control of the multiplicity of coupling at G-protein-coupled receptors
E. Hermans
Pharmacology & Therapeutics. 2003, 99, 25-44
Bifurcation of Lipid and Protein Kinase Signals of PI3K to the Protein Kinases PKB and MAPK
T. Bondeva
Science. 1998, 282, 293-296
Synergistic Activation of Phospholipase C-β3 by Gαq and Gβγ Describes a Simple Two-State Coincidence Detector
F. Philip, G. Kadamur, R. Silos, J. Woodson, E. Ross
Current Biology. 2010, 20, 1327-1335
The actin-binding protein profilin binds to PIP2 and inhibits its hydrolysis by phospholipase C
P. Goldschmidt-Clermont, L. Machesky, J. Baldassare, T. Pollard
Science. 1990, 247, 1575-1578
Structure, Function, and Control of Phosphoinositide-Specific Phospholipase C
M. Rebecchi, S. Pentyala
Physiological Reviews. 2000, 80, 1291-1335
Catalysis by Phospholipase C δ1 Requires That Ca2+ Bind to the Catalytic Domain, but Not the C2 Domain
J. Grobler, J. Hurley
Biochemistry. 1998, 37, 5020-5028
Activation of phospholipase C-beta 2 mutants by G protein alpha q and beta gamma subunits
Lee SB, Shin SH, Hepler JR, Gilman AG, Rhee SG.
Journal of Biological Chemistry. 1993, 268, 25952–7
The first comprehensive and quantitative analysis of human platelet protein composition allows the comparative analysis of structural and functional pathways
J. Burkhart, M. Vaudel, S. Gambaryan, S. Radau, U. Walter, L. Martens, J. Geiger, A. Sickmann, R. Zahedi
Blood. 2012, 120, e73-e82
Protein Kinase C in Oncogenic Transformation and Cell Polarity. In: Kramer IjM, editor. Signal Transduction (Third Edition)
Kramer IjM.
Boston: Academic Press. 2016, , 529–88
Purification and characterization of cytosolic diacylglycerol kinases of human platelets.
Y. Yada, T. Ozeki, H. Kanoh, Y. Nozawa
Journal of Biological Chemistry. 1990, 265, 19237-19243
Heterodimeric Phosphoinositide 3-Kinase Consisting of p85 and p110β Is Synergistically Activated by the βγ Subunits of G Proteins and Phosphotyrosyl Peptide
H. Kurosu, T. Maehama, T. Okada, T. Yamamoto, S. Hoshino, Y. Fukui, M. Ui, O. Hazeki, T. Katada
Journal of Biological Chemistry. 1997, 272, 24252-24256
Dichotomous regulation of myosin phosphorylation and shape change by Rho-kinase and calcium in intact human platelets
M Bauer, M Retzer, J I Wilde, P Maschberger, M Essler, M Aepfelbacher, S P Watson, W Siess
Blood. 1999, , 1665–72
Platelet Adenylyl Cyclase Activity: A Biological Marker for Major Depression and Recent Drug Use
L. Hines, B. Tabakoff
Biological Psychiatry. 2005, 58, 955-962
G-Protein–Coupled Receptors Signaling Pathways in New Antiplatelet Drug Development
P. Gurbel, A. Kuliopulos, U. Tantry
Arteriosclerosis, Thrombosis, and Vascular Biology. 2015, 35, 500-512
Fueling Platelets
S. Whiteheart
Arteriosclerosis, Thrombosis, and Vascular Biology. 2017, 37, 1592-1594
Signaling through Gi Family Members in Platelets
J. Yang, J. Wu, H. Jiang, R. Mortensen, S. Austin, D. Manning, D. Woulfe, L. Brass
Journal of Biological Chemistry. 2002, 277, 46035-46042
G-Protein Coupled Receptor Resensitization - Appreciating the Balancing Act of Receptor Function
M. L. Mohan, N. T. Vasudevan, M. K. Gupta, E. E. Martelli, S. V. Naga Prasad
Current Molecular Pharmacology. 2013, 5, 350-361
Heterogeneity of Integrin αIIbβ3 Function in Pediatric Immune Thrombocytopenia Revealed by Continuous Flow Cytometry Analysis
A. Martyanov, D. Morozova, M. Sorokina, A. Filkova, D. Fedorova, S. Uzueva, E. Suntsova, G. Novichkova, P. Zharkov, M. Panteleev, A. Sveshnikova
International Journal of Molecular Sciences. 2020, 21, 3035
Domains specifying thrombin–receptor interaction
T. Vu, V. Wheaton, D. Hung, I. Charo, S. Coughlin
Nature. 1991, 353, 674-677
RhoA downstream of Gq and G12/13 pathways regulates protease-activated receptor-mediated dense granule release in platelets
J. Jin, Y. Mao, D. Thomas, S. Kim, J. Daniel, S. Kunapuli
Biochemical Pharmacology. 2009, 77, 835-844
Primary haemostasis: newer insights
M. Berndt, P. Metharom, R. Andrews
Haemophilia. 2014, 20, 15-22
New Fundamentals in Hemostasis
H. Versteeg, J. Heemskerk, M. Levi, P. Reitsma
Physiological Reviews. 2013, 93, 327-358
Adenosine diphosphate (ADP)–induced thromboxane A2generation in human platelets requires coordinated signaling through integrin αIIbβ3 and ADP receptors
J. Jin, T. Quinton, J. Zhang, S. Rittenhouse, S. Kunapuli
Blood. 2002, 99, 193-198
Mechanisms of platelet activation: Need for new strategies to protect against platelet-mediated atherothrombosis
L. Jennings
Thrombosis and Haemostasis. 2009, 102, 248-257
Platelet adhesion, shape change, and aggregation: rapid initiation and signal transduction events
A. Gear
Canadian Journal of Physiology and Pharmacology. 1994, 72, 285-294
Defective platelet activation in Gαq-deficient mice
S. Offermanns, C. Toombs, Y. Hu, M. Simon
Nature. 1997, 389, 183-186
Metabolism of adenine nucleotides in human blood.
S. Coade, J. Pearson
Circulation Research. 1989, 65, 531-537
Demonstration of a novel ecto-enzyme on human erythrocytes, capable of degrading ADP and of inhibiting ADP-induced platelet aggregation
J. LUTHJE, A. SCHOMBURG, A. OGILVIE
European Journal of Biochemistry. 1988, 175, 285-289
The evolution of megakaryocytes to platelets
P. Nurden, C. Poujol, A. Nurden
Baillière's Clinical Haematology. 1997, 10, 1-27
Possible involvement of cytoskeleton in collagen-stimulated activation of phospholipases in human platelets
Nakano T, Hanasaki K, Arita H.
Journal of Biological Chemistry. 1989, 264, 5400-6
Detection of local ATP release from activated platelets using cell surface-attached firefly luciferase
R. Beigi, E. Kobatake, M. Aizawa, G. Dubyak
American Journal of Physiology-Cell Physiology. 1999, 276, C267-C278
Persistence of thromboxane A2-like material and platelet release-inducing activity in plasma.
J. Smith, C. Ingerman, M. Silver
Journal of Clinical Investigation. 1976, 58, 1119-1122
Signaling During Platelet Adhesion and Activation
Z. Li, M. Delaney, K. O'Brien, X. Du
Arteriosclerosis, Thrombosis, and Vascular Biology. 2010, 30, 2341-2349
Molecular Mechanisms of SERT in Platelets: Regulation of Plasma Serotonin Levels
C. Mercado, F. Kilic
Molecular Interventions. 2010, 10, 231-241
Epinephrine restores platelet functions inhibited by ticagrelor: A mechanistic approach
A. Martin, D. Zlotnik, G. Bonete, E. Baron, B. Decouture, T. Belleville-Rolland, B. Le Bonniec, S. Poirault-Chassac, M. Alessi, P. Gaussem, A. Godier, C. Bachelot-Loza
European Journal of Pharmacology. 2020, 866, 172798
Platelet ITAM signaling
W. Bergmeier, L. Stefanini
Current Opinion in Hematology. 2013, 20, 445-450
Platelet Immunoreceptor Tyrosine-Based Activation Motif (ITAM) Signaling and Vascular Integrity
Y. Boulaftali, P. Hess, M. Kahn, W. Bergmeier
Circulation Research. 2014, 114, 1174-1184
The Src, Syk, and Tec family kinases: Distinct types of molecular switches
J. Bradshaw
Cellular Signalling. 2010, 22, 1175-1184
Src family kinases: at the forefront of platelet activation
Y. Senis, A. Mazharian, J. Mori
Blood. 2014, 124, 2013-2024
Dominant Role of the Protein-Tyrosine Phosphatase CD148 in Regulating Platelet Activation Relative to Protein-Tyrosine Phosphatase-1B
J. Mori, Y. Wang, S. Ellison, S. Heising, B. Neel, M. Tremblay, S. Watson, Y. Senis
Arteriosclerosis, Thrombosis, and Vascular Biology. 2012, 32, 2956-2965
Mechanisms of receptor tyrosine kinase activation in cancer
Z. Du, C. Lovly
Molecular Cancer. 2018, 17,
SH2 domains: modulators of nonreceptor tyrosine kinase activity
P. Filippakopoulos, S. Müller, S. Knapp
Current Opinion in Structural Biology. 2009, 19, 643-649
SH3 domain ligand binding: What's the consensus and where's the specificity?
K. Saksela, P. Permi
FEBS Letters. 2012, 586, 2609-2614
Molecular priming of Lyn by GPVI enables an immune receptor to adopt a hemostatic role
A. Schmaier, Z. Zou, A. Kazlauskas, L. Emert-Sedlak, K. Fong, K. Neeves, S. Maloney, S. Diamond, S. Kunapuli, J. Ware, L. Brass, T. Smithgall, K. Saksela, M. Kahn
Proceedings of the National Academy of Sciences. 2009, 106, 21167-21172
Molecular Mechanism of the Syk Activation Switch
E. Tsang, A. Giannetti, D. Shaw, M. Dinh, J. Tse, S. Gandhi, H. Ho, S. Wang, E. Papp, J. Bradshaw
Journal of Biological Chemistry. 2008, 283, 32650-32659
The N-terminal SH2 domain of Syk is required for (hem)ITAM, but not integrin, signaling in mouse platelets
C. Hughes, B. Finney, F. Koentgen, K. Lowe, S. Watson
Blood. 2015, 125, 144-154
Dynamics of the Tec-family tyrosine kinase SH3 domains
J. Roberts, S. Tarafdar, R. Joseph, A. Andreotti, T. Smithgall, J. Engen, T. Wales
Protein Science. 2016, 25, 852-864
Ibrutinib-associated bleeding: pathogenesis, management and risk reduction strategies
J. Shatzel, S. Olson, D. Tao, O. McCarty, A. Danilov, T. DeLoughery
Journal of Thrombosis and Haemostasis. 2017, 15, 835-847
The transmembrane adapter LAT plays a central role in immune receptor signalling
P. Wonerow, S. Watson
Oncogene. 2001, 20, 6273-6283
Dual-Specificity Phosphatase 3 Deficiency or Inhibition Limits Platelet Activation and Arterial Thrombosis
L. Musumeci, M. Kuijpers, K. Gilio, A. Hego, E. Théâtre, L. Maurissen, M. Vandereyken, C. Diogo, C. Lecut, W. Guilmain, E. Bobkova, J. Eble, R. Dahl, P. Drion, J. Rascon, Y. Mostofi, H. Yuan, E. Sergienko, T. Chung, M. Thiry, Y. Senis, M. Moutschen, T. Mustelin, P. Lancellotti, J. Heemskerk, L. Tautz, C. Oury, S. Rahmouni
Circulation. 2015, 131, 656-668
ITIM receptors: more than just inhibitors of platelet activation
C. Coxon, M. Geer, Y. Senis
Blood. 2017, 129, 3407-3418
Functional significance of the platelet immune receptors GPVI and CLEC-2
J. Rayes, S. Watson, B. Nieswandt
Journal of Clinical Investigation. 2019, 129, 12-23
GPVI and CLEC-2 in hemostasis and vascular integrity
S. WATSON, J. HERBERT, A. POLLITT
Journal of Thrombosis and Haemostasis. 2010, 8, 1456-1467
Human platelet IgG Fc receptor FcγRIIA in immunity and thrombosis
M. Arman, K. Krauel
Journal of Thrombosis and Haemostasis. 2015, 13, 893-908
Signaling by ephrinB1 and Eph kinases in platelets promotes Rap1 activation, platelet adhesion, and aggregation via effector pathways that do not require phosphorylation of ephrinB1
N. Prévost, D. Woulfe, M. Tognolini, T. Tanaka, W. Jian, R. Fortna, H. Jiang, L. Brass
Blood. 2004, 103, 1348-1355
SLAM Family Receptors and SAP Adaptors in Immunity
J. Cannons, S. Tangye, P. Schwartzberg
Annual Review of Immunology. 2011, 29, 665-705
Platelet Inhibitory Receptors. In: Michelson AD, editor. Platelets (Fourth Edition)
Nagy Z, Senis YA
Academic Press. 2019, , 279-93
Minimal regulation of platelet activity by PECAM-1
T. Dhanjal, E. Ross, J. Auger, O. Mccarty, C. Hughes, Y. Senis, S. Watson
Platelets. 2007, 18, 56-67
Collagen, Convulxin, and Thrombin Stimulate Aggregation-independent Tyrosine Phosphorylation of CD31 in Platelets
M. Cicmil, J. Thomas, T. Sage, F. Barry, M. Leduc, C. Bon, J. Gibbins
Journal of Biological Chemistry. 2000, 275, 27339-27347
Thrombin-induced association of SHP-2 with multiple tyrosine-phosphorylated proteins in human platelets
C. Edmead, D. Crosby, M. Southcott, A. Poole
FEBS Letters. 1999, 459, 27-32
Differential association of cytoplasmic signalling molecules SHP-1, SHP-2, SHIP and phospholipase C-γ1 with PECAM-1/CD31
N. Pumphrey, V. Taylor, S. Freeman, M. Douglas, P. Bradfield, S. Young, J. Lord, M. Wakelam, I. Bird, M. Salmon, C. Buckley
FEBS Letters. 1999, 450, 77-83
Maintenance of murine platelet homeostasis by the kinase Csk and phosphatase CD148
J. Mori, Z. Nagy, G. Di Nunzio, C. Smith, M. Geer, R. Al Ghaithi, J. van Geffen, S. Heising, L. Boothman, B. Tullemans, J. Correia, L. Tee, M. Kuijpers, P. Harrison, J. Heemskerk, G. Jarvis, A. Tarakhovsky, A. Weiss, A. Mazharian, Y. Senis
Blood. 2018, 131, 1122-1144
An Investigation of Hierachical Protein Recruitment to the Inhibitory Platelet Receptor, G6B-b
C. Coxon, A. Sadler, J. Huo, R. Campbell
PLoS ONE. 2012, 7, e49543
Fibrin and D-dimer bind to monomeric GPVI
M. Onselaer, A. Hardy, C. Wilson, X. Sanchez, A. Babar, J. Miller, C. Watson, S. Watson, A. Bonna, H. Philippou, A. Herr, D. Mezzano, R. Ariëns, S. Watson
Blood Advances. 2017, 1, 1495-1504
Pharmacological Blockade of Glycoprotein VI Promotes Thrombus Disaggregation in the Absence of Thrombin
M. Ahmed, V. Kaneva, S. Loyau, D. Nechipurenko, N. Receveur, M. Le Bris, E. Janus-Bell, M. Didelot, A. Rauch, S. Susen, N. Chakfé, F. Lanza, E. Gardiner, R. Andrews, M. Panteleev, C. Gachet, M. Jandrot-Perrus, P. Mangin
Arteriosclerosis, Thrombosis, and Vascular Biology. 2020, 40, 2127-2142
Integrin αIIbβ3. In: Michelson AD, editor. Platelets (Fourth Edition)
Bledzka K, Qin J, Plow EF.
Academic Press. 2019, , 227–41
Comparison of the GPVI inhibitors losartan and honokiol
M. Onselaer, M. Nagy, C. Pallini, J. Pike, G. Perrella, L. Quintanilla, J. Eble, N. Poulter, J. Heemskerk, S. Watson
Platelets. 2020, 31, 187-197
Clustering of glycoprotein VI (GPVI) dimers upon adhesion to collagen as a mechanism to regulate GPVI signaling in platelets
N. Poulter, A. Pollitt, D. Owen, E. Gardiner, R. Andrews, H. Shimizu, D. Ishikawa, D. Bihan, R. Farndale, M. Moroi, S. Watson, S. Jung
Journal of Thrombosis and Haemostasis. 2017, 15, 549-564
Function of Platelet Glycosphingolipid Microdomains/Lipid Rafts
K. Komatsuya, K. Kaneko, K. Kasahara
International Journal of Molecular Sciences. 2020, 21, 5539
Role of PI3K/Akt signaling in memory CD8 T cell differentiation
E. Kim, M. Suresh
Frontiers in Immunology. 2013, 4,
Platelets and vascular integrity: how platelets prevent bleeding in inflammation
B. Ho-Tin-Noé, Y. Boulaftali, E. Camerer
Blood. 2018, 131, 277-288
Syk and Src Family Kinases Regulate C-type Lectin Receptor 2 (CLEC-2)-mediated Clustering of Podoplanin and Platelet Adhesion to Lymphatic Endothelial Cells
A. Pollitt, N. Poulter, E. Gitz, L. Navarro-Nuñez, Y. Wang, C. Hughes, S. Thomas, B. Nieswandt, M. Douglas, D. Owen, D. Jackson, M. Dustin, S. Watson
Journal of Biological Chemistry. 2014, 289, 35695-35710
Platelet GPIb complex as a target for anti-thrombotic drug development
J. Clemetson, K. Clemetson
Thrombosis and Haemostasis. 2008, 99, 473-479
Targeting Integrin and Integrin Signaling in Treating Thrombosis
B. Estevez, B. Shen, X. Du
Arteriosclerosis, Thrombosis, and Vascular Biology. 2015, 35, 24-29
Von Willebrand factor-A1 domain binds platelet glycoprotein Ibα in multiple states with distinctive force-dependent dissociation kinetics
L. Ju, Y. Chen, F. Zhou, H. Lu, M. Cruz, C. Zhu
Thrombosis Research. 2015, 136, 606-612
A short history of platelet glycoprotein Ib complex
Clemetson K
Thrombosis and Haemostasis. 2007, 98 (1), 63-8
Association of a phospholipase A2 (14-3-3 protein) with the platelet glycoprotein Ib-IX complex
X. Du, S. Harris, T. Tetaz, M. Ginsberg, M. Berndt
Journal of Biological Chemistry. 1994, 269, 18287-18290
The structure of the GPIb–filamin A complex
F. Nakamura, R. Pudas, O. Heikkinen, P. Permi, I. Kilpeläinen, A. Munday, J. Hartwig, T. Stossel, J. Ylänne
Blood. 2006, 107, 1925-1932
A functional 14-3-3ζ–independent association of PI3-kinase with glycoprotein Ibα, the major ligand-binding subunit of the platelet glycoprotein Ib-IX-V complex
F. Mu, R. Andrews, J. Arthur, A. Munday, S. Cranmer, S. Jackson, F. Stomski, A. Lopez, M. Berndt
Blood. 2008, 111, 4580-4587
Functional association of phosphoinositide-3-kinase with platelet glycoprotein Ibα, the major ligand-binding subunit of the glycoprotein Ib-IX-V complex
F. MU, S. CRANMER, R. ANDREWS, M. BERNDT
Journal of Thrombosis and Haemostasis. 2010, 8, 324-330
Platelet integrin αIIbβ3: signal transduction, regulation, and its therapeutic targeting
J. Huang, X. Li, X. Shi, M. Zhu, J. Wang, S. Huang, X. Huang, H. Wang, L. Li, H. Deng, Y. Zhou, J. Mao, Z. Long, Z. Ma, W. Ye, J. Pan, X. Xi, J. Jin
Journal of Hematology & Oncology. 2019, 12,
The platelet Fc receptor, FcγRIIa
J. Qiao, M. Al-Tamimi, R. Baker, R. Andrews, E. Gardiner
Immunological Reviews. 2015, 268, 241-252
Platelet Toll-like receptor expression and activation induced by lipopolysaccharide and sepsis
T. Claushuis, A. Van Der Veen, J. Horn, M. Schultz, R. Houtkooper, C. Van ’T Veer, T. Van Der Poll
Platelets. 2019, 30, 296-304
Platelet Toll-Like Receptors Mediate Thromboinflammatory Responses in Patients With Essential Thrombocythemia
C. Marín Oyarzún, A. Glembotsky, N. Goette, P. Lev, G. De Luca, M. Baroni Pietto, B. Moiraghi, M. Castro Ríos, A. Vicente, R. Marta, M. Schattner, P. Heller
Frontiers in Immunology. 2020, 11,
The inflammatory role of platelets via their TLRs and Siglec receptors
F. Cognasse
Frontiers in Immunology. 2015, 6,
Моделирование секреции гранул при активации тромбоцитов через TLR4-рецептор
Майоров А.С., Шепелюк Т.О., Балабин Ф.А., Мартьянов А.А., Нечипуренко Д.Ю., Свешникова А.Н.
Биофизика. 2018, 63 (3), 475-483
Akt signaling in platelets and thrombosis
D. Woulfe
Expert Review of Hematology. 2010, 3, 81-91
IκB kinase phosphorylation of SNAP-23 controls platelet secretion
Z. Karim, J. Zhang, M. Banerjee, M. Chicka, R. Al Hawas, T. Hamilton, P. Roche, S. Whiteheart
Blood. 2013, 121, 4567-4574
Platelet Toll-like receptor (TLR) expression and TLR-mediated platelet activation in acute myocardial infarction
K. Hally, A. La Flamme, P. Larsen, S. Harding
Thrombosis Research. 2017, 158, 8-15
Efficient phagocytosis of periodontopathogens by neutrophils requires plasma factors, platelets and TLR2
A. ASSINGER, M. LAKY, G. SCHABBAUER, A. HIRSCHL, E. BUCHBERGER, B. BINDER, I. VOLF
Journal of Thrombosis and Haemostasis. 2011, 9, 799-809
Stimulation of Toll-Like Receptor 2 in Human Platelets Induces a Thromboinflammatory Response Through Activation of Phosphoinositide 3-Kinase
P. Blair, S. Rex, O. Vitseva, L. Beaulieu, K. Tanriverdi, S. Chakrabarti, C. Hayashi, C. Genco, M. Iafrati, J. Freedman
Circulation Research. 2009, 104, 346-354
Periodontopathogens induce expression of CD40L on human platelets via TLR2 and TLR4
A. Assinger, M. Laky, S. Badrnya, A. Esfandeyari, I. Volf
Thrombosis Research. 2012, 130, e73-e78
The Role of Human Platelet Preparation for Toll-Like Receptors 2 and 4 Related Platelet Responsiveness
J. Koessler, M. Niklaus, K. Weber, A. Koessler, S. Kuhn, M. Boeck, A. Kobsar
TH Open. 2019, 03, e94-e102
Lipopolysaccharide as trigger of platelet aggregation via eicosanoid over-production
C. Nocella, R. Carnevale, S. Bartimoccia, M. Novo, R. Cangemi, D. Pastori, C. Calvieri, P. Pignatelli, F. Violi
Thrombosis and Haemostasis. 2017, 117, 1558-1570
The role of platelets in mediating a response to human influenza infection
M. Koupenova, H. Corkrey, O. Vitseva, G. Manni, C. Pang, L. Clancy, C. Yao, J. Rade, D. Levy, J. Wang, R. Finberg, E. Kurt-Jones, J. Freedman
Nature Communications. 2019, 10,
Revisiting Platelets and Toll-Like Receptors (TLRs): At the Interface of Vascular Immunity and Thrombosis
K. Hally, S. Fauteux-Daniel, H. Hamzeh-Cognasse, P. Larsen, F. Cognasse
International Journal of Molecular Sciences. 2020, 21, 6150
T granules in human platelets function in TLR9 organization and signaling
J. Thon, C. Peters, K. Machlus, R. Aslam, J. Rowley, H. Macleod, M. Devine, T. Fuchs, A. Weyrich, J. Semple, R. Flaumenhaft, J. Italiano
Journal of Cell Biology. 2012, 198, 561-574
Engagement of Platelet Toll-Like Receptor 9 by Novel Endogenous Ligands Promotes Platelet Hyperreactivity and Thrombosis
S. Panigrahi, Y. Ma, L. Hong, D. Gao, X. West, R. Salomon, T. Byzova, E. Podrez
Circulation Research. 2013, 112, 103-112
Mitochondria in lung biology and pathology: more than just a powerhouse
P. Schumacker, M. Gillespie, K. Nakahira, A. Choi, E. Crouser, C. Piantadosi, J. Bhattacharya
American Journal of Physiology-Lung Cellular and Molecular Physiology. 2014, 306, L962-L974
MITOCHONDRIAL DNA IS RELEASED BY SHOCK AND ACTIVATES NEUTROPHILS VIA P38 MAP KINASE
Q. Zhang, K. Itagaki, C. Hauser
Shock. 2010, 34, 55-59
Circulating mitochondrial DAMPs cause inflammatory responses to injury
Q. Zhang, M. Raoof, Y. Chen, Y. Sumi, T. Sursal, W. Junger, K. Brohi, K. Itagaki, C. Hauser
Nature. 2010, 464, 104-107
Platelets release mitochondria serving as substrate for bactericidal group IIA-secreted phospholipase A2 to promote inflammation
L. Boudreau, A. Duchez, N. Cloutier, D. Soulet, N. Martin, J. Bollinger, A. Paré, M. Rousseau, G. Naika, T. Lévesque, C. Laflamme, G. Marcoux, G. Lambeau, R. Farndale, M. Pouliot, H. Hamzeh-Cognasse, F. Cognasse, O. Garraud, P. Nigrovic, H. Guderley, S. Lacroix, L. Thibault, J. Semple, M. Gelb, E. Boilard
Blood. 2014, 124, 2173-2183
Mitochondrial DAMPs Increase Endothelial Permeability through Neutrophil Dependent and Independent Pathways
S. Sun, T. Sursal, Y. Adibnia, C. Zhao, Y. Zheng, H. Li, L. Otterbein, C. Hauser, K. Itagaki
PLoS ONE. 2013, 8, e59989
Toll-like receptor 9–dependent activation by DNA-containing immune complexes is mediated by HMGB1 and RAGE
J. Tian, A. Avalos, S. Mao, B. Chen, K. Senthil, H. Wu, P. Parroche, S. Drabic, D. Golenbock, C. Sirois, J. Hua, L. An, L. Audoly, G. La Rosa, A. Bierhaus, P. Naworth, A. Marshak-Rothstein, M. Crow, K. Fitzgerald, E. Latz, P. Kiener, A. Coyle
Nature Immunology. 2007, 8, 487-496
Induction of inflammatory and immune responses by HMGB1–nucleosome complexes: implications for the pathogenesis of SLE
V. Urbonaviciute, B. Fürnrohr, S. Meister, L. Munoz, P. Heyder, F. De Marchis, M. Bianchi, C. Kirschning, H. Wagner, A. Manfredi, J. Kalden, G. Schett, P. Rovere-Querini, M. Herrmann, R. Voll
Journal of Experimental Medicine. 2008, 205, 3007-3018
Platelets and Complement Cross-Talk in Early Atherogenesis
H. Kim, E. Conway
Frontiers in Cardiovascular Medicine. 2019, 6,
Vasodilator-Stimulated Phosphoprotein (VASP)-dependent and -independent pathways regulate thrombin-induced activation of Rap1b in platelets
P. Benz, H. Laban, J. Zink, L. Günther, U. Walter, S. Gambaryan, K. Dib
Cell Communication and Signaling. 2016, 14,
PGE1 and PGE2 modify platelet function through different prostanoid receptors
D. Iyú, M. Jüttner, J. Glenn, A. White, A. Johnson, S. Fox, S. Heptinstall
Prostaglandins & Other Lipid Mediators. 2011, 94, 9-16
Endothelial Function and Dysfunction
J. Deanfield, J. Halcox, T. Rabelink
Circulation. 2007, 115, 1285-1295
Platelet-Derived Nitric Oxide Signaling and Regulation
E. Gkaliagkousi, J. Ritter, A. Ferro
Circulation Research. 2007, 101, 654-662
Nitric oxide specifically inhibits integrin-mediated platelet adhesion and spreading on collagen
W. ROBERTS, R. RIBA, S. HOMER-VANNIASINKAM, R. FARNDALE, K. NASEEM
Journal of Thrombosis and Haemostasis. 2008, 6, 2175-2185
Platelets
Michelson AD.
Elsevier. 2013, ,
The unique contribution of ion channels to platelet and megakaryocyte function
M. MAHAUT-SMITH
Journal of Thrombosis and Haemostasis. 2012, 10, 1722-1732