Proteasome proteolysis supports stimulated platelet function and thrombosis.
Proteasome proteolysis supports stimulated platelet function and thrombosis.
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DOI：
10.1161/atvbaha.113.302116
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发表时间：
2014-01
期刊：
影响因子：
--
通讯作者：
McIntyre TM
中科院分区：
文献类型：
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作者：
Gupta N;Li W;Willard B;Silverstein RL;McIntyre TM
蛋白酶体抑制剂被用于治疗血液病癌症，但也减少血栓形成。蛋白酶体是否参与血小板活化或功能尚不清楚，因为对这些终末分化细胞中的蛋白酶体知之甚少。血小板显示出MG132和硼替佐米（Velcade®）抑制的所有三种初级蛋白酶体蛋白酶活性。蛋白酶体底物由泛素标记，血小板含有功能性泛素化系统，通过单泛素化和多泛素化修饰蛋白质组。在fecl3损伤的颈动脉中，全身MG132强烈抑制闭塞的、富含血小板的血栓的形成。输注经MG132体外处理并在输注血小板减少小鼠前清洗的血小板也可减少颈动脉血栓形成。蛋白酶体抑制通过低凝血酶浓度和利斯托司汀刺激的凝集通过GPIb-IX-V复合物降低血小板聚集。在受刺激的血小板中，蛋白酶体抑制后，该受体没有被适当地内化，MG132暴露后，扩散和凝块缩回也减少。蛋白酶体抑制剂的作用并不局限于单一受体，因为MG132抑制凝血酶，ADP和lps刺激的微粒脱落。蛋白酶体抑制增加了细胞质蛋白的泛素修饰，包括细胞骨架蛋白丝蛋白A和Talin-1。质谱分析显示，在延长的Filamin a环的R1745之后，存在一个mg132敏感的色氨酸切割，将其肌动蛋白结合域与羧基末端GPIbα结合域分离。血小板含有泛素/蛋白酶体系统，该系统标记细胞骨架蛋白进行蛋白水解修饰，以促进血小板-血小板和血小板-壁的相互作用。
Proteasome inhibitors are in use to treat hematologic cancers, but also reduce thrombosis. Whether the proteasome participates in platelet activation or function is opaque since little is known of the proteasome in these terminally differentiated cells. Platelets displayed all three primary proteasome protease activities, which MG132 and bortezomib (Velcade®) inhibited. Proteasome substrates are marked by ubiquitin, and platelets contained a functional ubiquitination system that modified the proteome by mono- and poly-ubiquitination. Systemic MG132 strongly suppressed formation of occlusive, platelet-rich thrombi in FeCl3-damaged carotid arteries. Transfusion of platelets treated ex vivo with MG132 and washed prior to transfusion into thrombocytopenic mice also reduced carotid artery thrombosis. Proteasome inhibition reduced platelet aggregation by low thrombin concentrations and ristocetin-stimulated agglutination through the GPIb-IX-V complex. This receptor was not appropriately internalized after proteasome inhibition in stimulated platelets, and spreading and clot retraction after MG132 exposure also were decreased. The effects of proteasome inhibitors were not confined to a single receptor as MG132 suppressed thrombin-, ADP-, and LPS-stimulated microparticle shedding. Proteasome inhibition increased ubiquitin decoration of cytoplasmic proteins, including the cytoskeletal proteins Filamin A and Talin-1. Mass spectrometry revealed a single MG132-sensitive tryptic cleavage after R1745 in an extended Filamin A loop, which would separate its actin-binding domain from its carboxy terminal GPIbα binding domain. Platelets contain a ubiquitin/proteasome system that marks cytoskeletal proteins for proteolytic modification to promote productive platelet-platelet and platelet-wall interactions.