Headpiece domain of dematin regulates calcium mobilization and signaling in platelets.
Headpiece domain of dematin regulates calcium mobilization and signaling in platelets.
复制标题
脱蛋白的头状结构域调节血小板中的钙动员和信号传导。
DOI：
10.1074/jbc.m112.364679
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Chishti,AtharH
中科院分区：
文献类型：
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作者：
Wieschhaus,AdamJ;LeBreton,GuyC;Chishti,AtharH
失调蛋白是一种广泛表达的膜细胞骨架蛋白，在红细胞中有很好的特征，在非红细胞中也有较少的特征。然而，痴呆蛋白在血小板中的功能尚不清楚。在这里，我们发现dematin在人和小鼠的血小板中都大量表达。从脱失蛋白头套敲除（HPKO）小鼠模型中收获的血小板在响应多种血小板激活激动剂时，在钙的动员方面表现出显著缺陷。HPKO血小板中钙动员的减少与血小板聚集和颗粒分泌的抑制有关。整合素α ib β3对激动剂的激活在HPKO血小板中减弱。突变血小板在纤维蛋白原和基础cAMP水平上的分布几乎正常；然而，在突变小鼠中，凝块收缩受到损害。免疫荧光分析表明，在血小板的致密管系统和质膜部分均存在失蛋白。对人血小板中痴呆相关蛋白进行蛋白质组学分析，发现肌醇1,4,5-三磷酸3-激酶异构体B （IP3KB）为结合伙伴，免疫沉淀分析证实了这一点。IP3KB是一种致密管系统蛋白，是钙稳态的主要调节因子。失乳蛋白头部的缺失导致膜上IP3KB的减少和细胞质中IP3KB的增加。总的来说，这些发现揭示了痴呆蛋白作为血小板内钙动员的一种新的调节剂，影响多种信号传导和细胞骨架功能。在其他细胞类型中，将讨论脑退化蛋白在钙稳态调节中的保守作用。
Dematin is a broadly expressed membrane cytoskeletal protein that has been well characterized in erythrocytes and to a lesser extent in non-erythroid cells. However, dematin's function in platelets is not known. Here, we show that dematin is abundantly expressed in both human and mouse platelets. Platelets harvested from the dematin headpiece knock-out (HPKO) mouse model exhibit a striking defect in the mobilization of calcium in response to multiple agonists of platelet activation. The reduced calcium mobilization in HPKO platelets is associated with concomitant inhibition of platelet aggregation and granule secretion. Integrin αIIbβ3activation in response to agonists is attenuated in the HPKO platelets. The mutant platelets show nearly normal spreading on fibrinogen and an unaltered basal cAMP level; however, the clot retraction was compromised in the mutant mice. Immunofluorescence analysis indicated that dematin is present both at the dense tubular system and plasma membrane fractions of platelets. Proteomic analysis of dematin-associated proteins in human platelets identified inositol 1,4,5-trisphosphate 3-kinase isoform B (IP3KB) as a binding partner, which was confirmed by immunoprecipitation analysis. IP3KB, a dense tubular system protein, is a major regulator of calcium homeostasis. Loss of the dematin headpiece resulted in a decrease of IP3KB at the membrane and increased levels of IP3KB in the cytosol. Collectively, these findings unveil dematin as a novel regulator of internal calcium mobilization in platelets affecting multiple signaling and cytoskeletal functions. Implications of a conserved role of dematin in the regulation of calcium homeostasis in other cell types will be discussed.