Abstract

Platelets are nuclear-free cell fragments responsible for preventing blood loss in case of the vascular wall injury. After a contact with collagen exposed when the vessel is damaged, platelets become activated through the receptor glycoprotein GPVI. This leads to platelet shape change, degranulation, aggregation, and procoagulant responses. The aim of this study was to observe changes in the concentration of Ca²⁺ in the cytosol and functional responses of platelets upon stimulation through the GPVI receptor. The study involved healthy adult volunteers and house mice Mus musculus of the C57Bl6 line (wild type). Calcium signaling was monitored by Fura-Red fluorophore fluorescence using BD FACS Canto II flow cytometer. Functional responses were observed on a flow cytometer by binding of human fibrinogen conjugated to a fluorescent label or by Biola optical aggregometry. When tested on a cytometer, platelets were activated by collagen-related peptide CRP and when tested by aggregometry, platelets were activated using collagen. As a result of the study, the following phenomenon was revealed: despite a significant variability in the human platelet cytosolic Ca²⁺ levels in response to stimulation, the variability in activation of platelet integrins, shape change, and the aggregation response was significantly lower. No variability in the platelet cytosolic Ca²⁺ levels in response to stimulation was observed in mice. The observed variability of the calcium response of platelets could be caused by differences in the GPVI expression or polymorphisms of the GPVI receptor gene in the studied donors. Similarities in the functional responses of platelets with different signaling suggest a variable contribution of the phosphoinositide branch of intracellular signaling in platelets in response to activation of GPVI.

中文翻译：

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通过GPVI受体激活血小板：反应的变异性

摘要

血小板是无核细胞碎片，可在血管壁损伤的情况下防止失血。与血管受损时暴露的胶原蛋白接触后，血小板通过受体糖蛋白GPVI活化。这导致血小板形状改变，脱粒，聚集和促凝血反应。这项研究的目的是观察通过GPVI受体刺激后细胞质中Ca ²⁺浓度的变化和血小板的功能反应。该研究涉及健康的成年志愿者和家鼠小家鼠C57Bl6线（野生型）。使用BD FACS Canto II流式细胞仪通过Fura-Red荧光团荧光监测钙信号。在流式细胞仪上通过结合到荧光标记物上的人血纤蛋白原的结合或通过Biola光学聚集法观察到功能性反应。当在细胞仪上测试时，血小板被胶原相关肽CRP激活，而当通过凝集测定法测试时，血小板被胶原激活。研究的结果揭示了以下现象：尽管人体血小板胞浆Ca ²⁺水平响应刺激有显着变化，但血小板整合素激活，形状变化和聚集响应的变化却明显较低。血小板胞浆Ca ²⁺没有变化在小鼠中观察到对刺激的响应水平。所观察到的血小板钙反应的变异性可能是由于研究供体中GPVI表达的差异或GPVI受体基因的多态性引起的。具有不同信号传导的血小板的功能应答中的相似性表明，响应GPVI的活化，血小板内细胞内信号传导的磷酸肌醇分支的可变贡献。