Pugh Nicholas, Maddox Ben D, Bihan Dominique, Taylor Kirk A, Mahaut-Smith Martyn P, Farndale Richard W
Nicholas Pugh, Department of Biomedical and Forensic Sciences, Anglia Ruskin University, Cambridge, CB1 1PT, UK, Tel.: +44 8451962661, E-mail:
Thromb Haemost. 2017 Jul 26;117(8):1588-1600. doi: 10.1160/TH16-12-0906. Epub 2017 May 24.
The platelet receptors glycoprotein (Gp)VI, integrin αβ and GpIb/V/IX mediate platelet adhesion and activation during thrombogenesis. Increases of intracellular Ca ([Ca]) are key signals during platelet activation; however, their relative importance in coupling different collagen receptors to functional responses under shear conditions remains unclear. To study shear-dependent, receptor-specific platelet responses, we used collagen or combinations of receptor-specific collagen-mimetic peptides as substrates for platelet adhesion and activation in whole human blood under arterial flow conditions and compared real-time and endpoint parameters of thrombus formation alongside [Ca] measurements using confocal imaging. All three collagen receptors coupled to [Ca] signals, but these varied in amplitude and temporal pattern alongside variable integrin activation. GpVI engagement produced large, sustained [Ca] signals leading to real-time increases in integrins αβ- and αβ-mediated platelet adhesion. αβ-dependent platelet aggregation was dependent on PY signalling. Co-engagement of αβ and GpIb/V/IX generated transient [Ca] spikes and low amplitude [Ca] responses that potentiated GpVI-dependent [Ca] signalling. Therefore αβ, GpIb/V/IX and GpVI synergise to generate [Ca] signals that regulate platelet behaviour and thrombus formation. Antagonism of secondary signalling pathways reveals distinct, separate roles for αβ in stable platelet adhesion and aggregation.
血小板受体糖蛋白（Gp）VI、整合素αβ和GpIb/V/IX在血栓形成过程中介导血小板黏附和激活。细胞内钙离子（[Ca]）浓度升高是血小板激活过程中的关键信号；然而，在剪切条件下，它们在将不同胶原受体与功能反应偶联中的相对重要性仍不清楚。为了研究剪切力依赖性、受体特异性的血小板反应，我们使用胶原或受体特异性胶原模拟肽组合作为底物，在动脉血流条件下的全血中进行血小板黏附和激活，并使用共聚焦成像比较血栓形成的实时和终点参数以及[Ca]测量值。所有三种胶原受体均与[Ca]信号偶联，但这些信号在幅度和时间模式上有所不同，同时整合素激活也存在差异。GpVI的激活产生大的、持续的[Ca]信号，导致整合素αβ和αβ介导的血小板黏附实时增加。αβ依赖性血小板聚集依赖于PY信号传导。αβ和GpIb/V/IX的共同激活产生短暂的[Ca]峰值和低幅度[Ca]反应，增强了GpVI依赖性[Ca]信号传导。因此，αβ、GpIb/V/IX和GpVI协同作用产生调节血小板行为和血栓形成的[Ca]信号。对二级信号通路的拮抗揭示了αβ在稳定血小板黏附和聚集中的不同、独立作用。
