Naik Meghna U, Patel Pravin, Derstine Randall, Turaga Ramya, Chen Xi, Golla Kalyan, Neeves Keith B, Ichijo Hidenori, Naik Ulhas P
Cardeza Center for Vascular Biology, Department of Medicine, Thomas Jefferson University, Philadelphia, PA.
Department of Biological Sciences, University of Delaware, Newark, DE.
Blood. 2017 Mar 2;129(9):1197-1209. doi: 10.1182/blood-2016-07-729780. Epub 2016 Dec 27.
Mitogen-activated protein kinases (MAPKs) are expressed in platelets and are activated downstream of physiological agonists. Pharmacological and genetic evidence indicate that MAPKs play a significant role in hemostasis and thrombosis, but it is not well understood how MAPKs are activated upon platelet stimulation. Here, we show that apoptosis signal-regulating kinase 1 (ASK1), a member of the MAP3K family, is expressed in both human and murine platelets. ASK1 is rapidly and robustly activated upon platelet stimulation by physiological agonists. Disruption of ( ) resulted in a marked functional defect in platelets. platelets showed an impaired agonist-induced integrin αβ activation and platelet aggregation. Although there was no difference in Ca rise, platelet granule secretion and thromboxane A (TxA) generation were significantly attenuated in platelets. The defective granule secretion observed in platelets was a consequence of impaired TxA generation. Biochemical studies showed that platelet agonists failed to activate p38 MAPK in platelets. On the contrary, activation of c-Jun -terminal kinases and extracellular signal-regulated kinase 1/2 MAPKs was augmented in platelets. The defect in p38 MAPK results in failed phosphorylation of cPLA in platelets and impaired platelet aggregate formation under flow. The absence of Ask1 renders mice defective in hemostasis as assessed by prolonged tail-bleeding times. Deletion of also reduces thrombosis as assessed by delayed vessel occlusion of carotid artery after FeCl-induced injury and protects against collagen/epinephrine-induced pulmonary thromboembolism. These results suggest that the platelet Ask1 plays an important role in regulation of hemostasis and thrombosis.
丝裂原活化蛋白激酶（MAPKs）在血小板中表达，并在生理性激动剂下游被激活。药理学和遗传学证据表明，MAPKs在止血和血栓形成中起重要作用，但目前尚不清楚MAPKs在血小板刺激时是如何被激活的。在此，我们表明凋亡信号调节激酶1（ASK1）是MAP3K家族的成员，在人和小鼠血小板中均有表达。ASK1在生理性激动剂刺激血小板后迅速且强烈地被激活。（此处括号内容缺失无法准确翻译）的破坏导致血小板出现明显的功能缺陷。（此处相关血小板描述缺失无法准确翻译）血小板显示出激动剂诱导的整合素αβ活化受损和血小板聚集受损。尽管钙离子升高没有差异，但（此处相关血小板描述缺失无法准确翻译）血小板中的血小板颗粒分泌和血栓素A（TxA）生成显著减弱。在（此处相关血小板描述缺失无法准确翻译）血小板中观察到的颗粒分泌缺陷是TxA生成受损的结果。生化研究表明，血小板激动剂未能在（此处相关血小板描述缺失无法准确翻译）血小板中激活p38 MAPK。相反，c-Jun末端激酶和细胞外信号调节激酶1/2 MAPKs的激活在（此处相关血小板描述缺失无法准确翻译）血小板中增强。p38 MAPK的缺陷导致（此处相关血小板描述缺失无法准确翻译）血小板中cPLA磷酸化失败以及在血流条件下血小板聚集形成受损。通过延长的尾部出血时间评估，Ask1的缺失使小鼠在止血方面存在缺陷。通过FeCl诱导损伤后颈动脉延迟血管闭塞评估，Ask1的缺失也减少了血栓形成，并预防胶原/肾上腺素诱导的肺血栓栓塞。这些结果表明血小板Ask1在止血和血栓形成的调节中起重要作用。
