Platelet Receptor Proteolysis

Andrews, Robert K.; Karunakaran, Denuja; Gardiner, Elizabeth E.; Berndt, Michael C.

doi:10.1161/atvbaha.107.141390

Cited by 88 publications

(27 citation statements)

References 118 publications

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“…Furthermore, GPIb-V-IX binds with high affinity to thrombin, which can support thrombin-induced activation of the receptors PAR1 and PAR4, although the physiological importance of the GPIb pathway is debated (68). In addition, GPIb␣ has been reported to bind the coagulation factors FXI, FXII, and high-molecular-weight kininogen (7) and may also function as a coreceptor for FVIIa (314) and FXI(a) (17). On the other hand, recent findings suggest that FXI binds to platelets via the receptor LRP8 (ApoeER2) (317).…”

Section: A Platelet Leucine-rich Repeat and Immunoglobulin Family Rementioning

confidence: 99%

New Fundamentals in Hemostasis

Versteeg

Heemskerk

Levi

et al. 2013

Physiological Reviews

893

831

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Hemostasis encompasses the tightly regulated processes of blood clotting, platelet activation, and vascular repair. After wounding, the hemostatic system engages a plethora of vascular and extravascular receptors that act in concert with blood components to seal off the damage inflicted to the vasculature and the surrounding tissue. The first important component that contributes to hemostasis is the coagulation system, while the second important component starts with platelet activation, which not only contributes to the hemostatic plug, but also accelerates the coagulation system. Eventually, coagulation and platelet activation are switched off by blood-borne inhibitors and proteolytic feedback loops. This review summarizes new concepts of activation of proteases that regulate coagulation and anticoagulation, to give rise to transient thrombin generation and fibrin clot formation. It further speculates on the (patho)physiological roles of intra-and extravascular receptors that operate in response to these proteases. Furthermore, this review provides a new framework for understanding how signaling and adhesive interactions between endothelial cells, leukocytes, and platelets can regulate thrombus formation and modulate the coagulation process. Now that the key molecular players of coagulation and platelet activation have become clear, and their complex interactions with the vessel wall have been mapped out, we can also better speculate on the causes of thrombosis-related angiopathies.

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Section: A Platelet Leucine-rich Repeat and Immunoglobulin Family Rementioning

confidence: 99%

New Fundamentals in Hemostasis

Versteeg

Heemskerk

Levi

et al. 2013

Physiological Reviews

893

831

View full text Add to dashboard Cite

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“…23,24,26,27,43 To ascertain whether fibrin could induce GPVI shedding, we first assessed the effect of thrombin or other GPCR ligands on GPVI levels. GPVI shedding was calculated as a percentage of GPVI detected in unstimulated samples compared with GPVI levels after stimulation.…”

Section: Exposure Of Platelets To Fibrin But Not Gpcr Stimulation Imentioning

confidence: 99%

Soluble GPVI is elevated in injured patients: shedding is mediated by fibrin activation of GPVI

Montague

Delierneux

Lecut³

et al. 2018

Blood Advances

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• Soluble GPVI is elevated in patients with thermal injury with sepsis, and sGPVI levels augment severity score prediction of mortality.• The GPVI ligand, fibrin, induces GPVI shedding without requirement for platelet activation or signaling Soluble glycoprotein VI (sGPVI) is shed from the platelet surface and is a marker of platelet activation in thrombotic conditions. We assessed sGPVI levels together with patient and clinical parameters in acute and chronic inflammatory conditions, including patients with thermal injury and inflammatory bowel disease and patients admitted to the intensive care unit (ICU)for elective cardiac surgery, trauma, acute brain injury, or prolonged ventilation. Plasma sGPVI was measured by enzyme-linked immunosorbent assay and was elevated on day 14 after thermal injury, and was higher in patients who developed sepsis. sGPVI levels were associated with sepsis, and the value for predicting sepsis was increased in combination with platelet count and Abbreviated Burn Severity Index. sGPVI levels positively correlated with levels of D-dimer (a fibrin degradation product) in ICU patients and patients with thermal injury. sGPVI levels in ICU patients at admission were significantly associated with 28-and 90-day mortality independent of platelet count. sGPVI levels in patients with thermal injury were associated with 28-day mortality at days 1, 14, and 21 when adjusting for platelet count. In both cohorts, sGPVI associations with mortality were stronger than D-dimer levels. Mechanistically, release of GPVI was triggered by exposure of platelets to polymerized fibrin, but not by engagement of G protein-coupled receptors by thrombin, adenosine 59-diphosphate, or thromboxane mimetics. Enhanced fibrin production in these patients may therefore contribute to the observed elevated sGPVI levels. sGPVI is an important platelet-specific marker for platelet activation that predicts sepsis progression and mortality in injured patients.

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“…Thus, ectodomain shedding of platelet adheso-signaling receptors, GP Ibα and GP VI, would provide an attractive mechanism for limiting thrombus growth and stability. 109 Another mechanism contributing to restrict thrombus growth under flow is the cleavage by ADAMS13 of VWF engaged in thrombi surface, as suggested by recent perfusion experiments in the presence of a functionblocking antibody against this metalloprotease. …”

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confidence: 99%

Platelet receptors and signaling in the dynamics of thrombus formation

Rivera¹,

Lozano²,

et al. 2009

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Hemostasis and pathological thrombus formation are dynamic processes that require a co-ordinated series of events involving platelet membrane receptors, bidirectional intracellular signals, and release of platelet proteins and inflammatory substances. This review aims to summarize current knowledge in the key steps in the dynamics of thrombus formation, with special emphasis on the crucial participation of platelet receptors and signaling in this process. Initial tethering and firm adhesion of platelets to the exposed subendothelium is mediated by glycoprotein (GP) Ib/IX/V complex and collagen receptors, GP VI and α2β1 integrin, in the platelet surface, and by VWF and fibrillar collagen in the vascular site. Interactions between these elements are largely influenced by flow and trigger signaling events that reinforce adhesion and promote platelet activation. Thereafter, soluble agonists, ADP, thrombin, TxA2, produced/released at the site of vascular injury act in autocrine and paracrine mode to amplify platelet activation and to recruit circulating platelets to the developing thrombus. Specific interactions of these agonists with their G-protein coupled receptors generate inside-out signaling leading to conformational activation of integrins, in particular αIIbβ3, increasing their ligand affinity. Binding of αIIbβ3 to its ligands, mainly fibrinogen, supports processes such as clot retraction and platelet aggregation. Stabilization of thrombi is supported by the late wave of signaling events promoted by close contact between aggregated platelets. The best known contact-dependent signaling is outside-in signaling through αIIbβ3, but new ones are being clarified such as those mediated by interaction of Eph receptors with ephrins, or by Sema 4D and Gas-6 binding to their receptors. Finally, newly identified mechanisms appear to control thrombus growth, including back-shifting of activated integrins and actuation of compensatory molecules such as ESAM or PECAM-1. The expanding knowledge of thrombotic disease is expected to translate into the development of new drugs to help management and prevention of thrombosis.Key words: platelet, receptors, thrombus formation.Citation: Rivera J, Lozano ML, Navarro-Núñez L, Vicente V. Platelet receptors and signaling in the dynamics of thrombus formation. Haematologica 2009; 94:700-711. doi:10.3324/haematol.2008 This is an open-access paper. ABSTRACT Platelet receptors and signaling in the dynamics of thrombus formationJosé Rivera, María Luisa Lozano, Leyre Navarro-Núñez, and Vicente Vicente Unit of Hematology and Clinical Oncology, Centro Regional de Hemodonación, University of Murcia, Spain © F e r r a t a S t o r t i F o u n d a t i o nand metastasis, or immunological host defense. 1Internally, platelets contain a cytoskeleton, a dense tubular system, few mitochondrias, glycogen granules, dense (δ) and α storage granules and peroxisomes. The α-granules retain relevant proteins for the hemostatic function of platelets, such as von Willebrand factor (VWF), fibrinogen, P-selectin,...

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Platelet Receptor Proteolysis

Cited by 88 publications

References 118 publications

New Fundamentals in Hemostasis

New Fundamentals in Hemostasis

Soluble GPVI is elevated in injured patients: shedding is mediated by fibrin activation of GPVI

Platelet receptors and signaling in the dynamics of thrombus formation

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