Class III PI3K Positively Regulates Platelet Activation and Thrombosis via PI(3) P-Directed Function of NADPH Oxidase
Class III PI3K Positively Regulates Platelet Activation and Thrombosis via PI(3) P-Directed Function of NADPH Oxidase
复制标题
III 类 PI3K 通过 NADPH 氧化酶的 PI(3)P 导向功能积极调节血小板活化和血栓形成
DOI：
10.1161/atvbaha.117.309751
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发表时间：
2017-01-01
影响因子：
8.7
通讯作者：
Hu, Hu
中科院分区：
文献类型：
--
作者：
Liu, Yangyang;Hu, Mengjiao;Hu, Hu
β-III类磷酸肌醇3-激酶，也称为VPS 34（vacuolar protein sorting 34），是一种高度保守的酶，调节重要的细胞功能，如NADPH氧化酶（NOX）组装、膜运输和自噬。尽管VPS 34在血小板中表达，但其参与血小板活化仍不清楚。在此，我们使用VPS 34基因敲除小鼠研究了VPS 34在血小板活化和血栓形成中的作用。血小板中VPS 34缺陷不影响尾部出血时间。在氯化铁诱导的肠系膜小动脉血栓形成模型中，与野生型小鼠相比，VPS 34（-/-）小鼠表现出较长的血管闭塞时间（42.05 +/- 4.09 vs 18.30 +/- 2.47分钟）。在体外微流控全血灌注测定中，VPS 34（-/-）血小板在动脉剪切下胶原上的血栓形成显著减少。VPS 34（-/-）血小板显示受损的聚集和致密颗粒分泌响应于低剂量的胶原蛋白或凝血酶。VPS 34缺陷延迟凝块收缩，但不影响血小板在纤维蛋白原上的铺展。我们还证明，VPS 34缺陷改变了静息血小板中自噬的基础水平，并在血小板活化过程中阻碍了NOX组装和mTOR（哺乳动物雷帕霉素靶蛋白）信号传导。重要的是，我们确定了NOX依赖性活性氧物质的产生作为VPS 34的主要下游效应物，VPS 34反过来可以介导血小板活化。此外，通过使用一个特定的抑制剂3-甲基腺嘌呤，VPS 34被发现通过一个类似的NOX依赖的机制，以促进人类platelet activation.Conclusions-Platelet VPS 34是血栓形成的关键，但止血的作用。VPS 34通过影响NOX组装来调节血小板活化。
Objective-Class III phosphoinositide 3-kinase, also known as VPS34 (vacuolar protein sorting 34), is a highly conserved enzyme regulating important cellular functions such as NADPH oxidase (NOX) assembly, membrane trafficking, and autophagy. Although VPS34 is expressed in platelets, its involvement in platelet activation remains unclear. Herein, we investigated the role of VPS34 in platelet activation and thrombus formation using VPS34 knockout mice.Approach and Results-Platelet-specific VPS34-deficient mice were generated and characterized. VPS34 deficiency in platelets did not influence tail bleeding time. In a ferric chloride-induced mesenteric arteriolar thrombosis model, VPS34(-/-) mice exhibited a prolonged vessel occlusion time compared with wild-type mice (42.05 +/- 4.09 versus 18.30 +/- 2.47 minutes). In an in vitro microfluidic whole-blood perfusion assay, thrombus formation on collagen under arterial shear was significantly reduced for VPS34(-/-) platelets. VPS34(-/-) platelets displayed an impaired aggregation and dense granule secretion in response to low doses of collagen or thrombin. VPS34 deficiency delayed clot retraction but did not influence platelet spreading on fibrinogen. We also demonstrated that VPS34 deficiency altered the basal level of autophagy in resting platelets and hampered NOX assembly and mTOR (mammalian target of rapamycin) signaling during platelet activation. Importantly, we identified the NOX-dependent reactive oxygen species generation as the major downstream effector of VPS34, which in turn can mediate platelet activation. In addition, by using a specific inhibitor 3-methyladenine, VPS34 was found to operate through a similar NOX-dependent mechanism to promote human platelet activation.Conclusions-Platelet VPS34 is critical for thrombosis but dispensable for hemostasis. VPS34 regulates platelet activation by influencing NOX assembly.