PDK1 Determines Collagen-Dependent Platelet Ca2+ Signaling and Is Critical to Development of Ischemic Stroke In Vivo
PDK1 Determines Collagen-Dependent Platelet Ca2+ Signaling and Is Critical to Development of Ischemic Stroke In Vivo
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DOI：
10.1161/atvbaha.115.307105
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发表时间：
2016-08-01
影响因子：
8.7
通讯作者：
Borst, Oliver
中科院分区：
文献类型：
--
作者：
Muenzer, Patrick;Walker-Allgaier, Britta;Borst, Oliver
目的内皮下胶原激活血小板，引起细胞内钙离子浓度([Ca~(2+)](I))升高，继而导致血小板活化和血栓形成，导致血管闭塞。本研究探讨了磷脂酰肌醇依赖的蛋白激酶1(PDK1)在活体胶原依赖的血小板钙信号转导和缺血性卒中中的作用。方法和结果用VI型胶原受体激动剂、胶原相关肽或惊厥毒素激活血小板后，PDK1活性显著增加，而不依赖于第二波信号。PDK1缺乏与血小板磷脂酶C2依赖的三磷酸肌醇的产生和细胞内[Ca~(2+)](I)对胶原相关肽或惊厥毒素刺激的反应减少有关。[Ca~(2+)](I)的缺陷增加导致激活依赖的血小板分泌和聚集在胶原相关肽刺激上的实质性缺陷。此外，在PDK1缺乏的血小板中，在动脉切变率较高的情况下，rac1的激活和扩散、与胶原的黏附和血栓形成显著减少。体内实验显示，PDK1基因缺陷的小鼠可预防FeCl3诱导的肠系膜小动脉损伤和缺血性卒中后的动脉血栓闭塞。这些小鼠显著减少了脑梗塞体积，在没有增加脑内出血的情况下，短暂大脑中动脉闭塞后7天的存活率显著增加。PDK1(-/-)小鼠尾部出血时间延长，反映了PDK1在初次止血中的重要作用。结论PDK1在体内依赖钙激活的血小板活化、动脉血栓闭塞和缺血性卒中中是必需的。
Objective Activation of platelets by subendothelial collagen results in an increase of cytosolic Ca2+ concentration ([Ca2+](i)) and is followed by platelet activation and thrombus formation that may lead to vascular occlusion. The present study determined the role of phosphoinositide-dependent protein kinase 1 (PDK1) in collagen-dependent platelet Ca2+ signaling and ischemic stroke in vivo.Approach and Results Platelet activation with collagen receptor glycoprotein VI agonists collagen-related peptide or convulxin resulted in a significant increase in PDK1 activity independent of second-wave signaling. PDK1 deficiency was associated with reduced platelet phospholipase C2-dependent inositol-1,4,5-trisphosphate production and intracellular [Ca2+](i) in response to stimulation with collagen-related peptide or convulxin. The defective increase of [Ca2+](i) resulted in a substantial defect in activation-dependent platelet secretion and aggregation on collagen-related peptide stimulation. Furthermore, Rac1 activation and spreading, adhesion to collagen, and thrombus formation under high arterial shear rates were significantly diminished in PDK1-deficient platelets. Mice with PDK1-deficient platelets were protected against arterial thrombotic occlusion after FeCl3-induced mesenteric arterioles injury and ischemic stroke in vivo. These mice had significantly reduced brain infarct volumes, with a significantly increased survival of 7 days after transient middle cerebral artery occlusion without increase of intracerebral hemorrhage. Tail bleeding time was prolonged in pdk1(-/-) mice, reflecting an important role of PDK1 in primary hemostasis.Conclusions PDK1 is required for Ca2+-dependent platelet activation on stimulation of collagen receptor glycoprotein VI, arterial thrombotic occlusion, and ischemic stroke in vivo.