Protease-Activated Receptor (PAR) 1 and PAR4 Differentially Regulate Factor V Expression from Human Platelets
Protease-Activated Receptor (PAR) 1 and PAR4 Differentially Regulate Factor V Expression from Human Platelets
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DOI：
10.1124/mol.112.083477
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发表时间：
2013-04-01
影响因子：
3.6
通讯作者：
Hamm, Heidi
中科院分区：
文献类型：
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作者：
Duvernay, Matthew;Young, Summer;Hamm, Heidi
随着最近的兴趣蛋白酶激活受体（PAR）1和PAR 4作为治疗血栓性疾病的可能目标，我们比较了蛋白酶激活受体（PAR）1和PAR 4在血小板膜上产生促凝血表型的功效。PAR 4-活化肽（AP）刺激的血小板促进血浆中凝血酶的产生比PAR 1-AP刺激的血小板早5分钟。PAR 4-AP介导的因子V（FV）与血小板表面的结合是PAR 1-AP的1.6倍。此外，与PAR 1刺激相比，PAR 4刺激导致3倍更大的微粒释放。使用PAR 4-AP的更强的FV分泌和微粒产生归因于肌球蛋白轻链在丝氨酸19和苏氨酸18处的更强和更持续的磷酸化。Rho激酶的抑制将PAR 4-AP介导的FV分泌和微粒产生降低至PAR 1-AP介导的水平。凝血酶生成测定法测量凝血酶原酶复合物活性，结果显示PAR 4-AP刺激的血小板上的凝血酶峰值水平比PAR 1-AP刺激的血小板高1.5倍。Rho激酶抑制剂使PAR 4-AP介导的凝血酶生成峰值降低25%，但对PAR 1-AP介导的凝血酶生成无显著影响。总之，与PAR 1刺激相比，PAR 4对血小板的刺激导致更快和更稳健的凝血酶生成。更大的促凝血潜力与更有效的FV从细胞内储存释放以及由更强和更持续的肌球蛋白轻链磷酸化驱动的微粒产生有关。这些数据表明PAR 4在止血过程中的作用，并且根据最近开发PAR拮抗剂治疗血栓性疾病的努力，这些数据具有临床相关性。
With the recent interest of protease-activated receptors (PAR) 1 and PAR4 as possible targets for the treatment of thrombotic disorders, we compared the efficacy of protease-activated receptor (PAR) 1 and PAR4 in the generation of procoagulant phenotypes on platelet membranes. PAR4-activating peptide (AP)-stimulated platelets promoted thrombin generation in plasma up to 5 minutes earlier than PAR1-AP-stimulated platelets. PAR4-AP-mediated factor V (FV) association with the platelet surface was 1.6-fold greater than for PAR1-AP. Moreover, PAR4 stimulation resulted in a 3-fold greater release of microparticles, compared with PAR1 stimulation. More robust FV secretion and microparticle generation with PAR4-AP was attributable to stronger and more sustained phosphorylation of myosin light chain at serine 19 and threonine 18. Inhibition of Rho-kinase reduced PAR4-AP-mediated FV secretion and microparticle generation to PAR1-AP-mediated levels. Thrombin generation assays measuring prothrombinase complex activity demonstrated 1.5-fold higher peak thrombin levels on PAR4-AP-stimulated platelets, compared with PAR1-AP-stimulated platelets. Rho-kinase inhibition reduced PAR4-AP-mediated peak thrombin generation by 25% but had no significant effect on PAR1-AP-mediated thrombin generation. In conclusion, stimulation of PAR4 on platelets leads to faster and more robust thrombin generation, compared with PAR1 stimulation. The greater procoagulant potential is related to more efficient FV release from intracellular stores and microparticle production driven by stronger and more sustained myosin light chain phosphorylation. These data have implications about the role of PAR4 during hemostasis and are clinically relevant in light of recent efforts to develop PAR antagonists to treat thrombotic disorders.