Austin Richard C, Fox Joan E B, Werstuck Geoff H, Stafford Alan R, Bulman Dennis E, Dally Ghassan Y, Ackerley Cameron A, Weitz Jeffrey I, Ray Peter N
Department of Pathology, McMaster University and the Henderson Research Centre, Hamilton, Ontario L8V 1C3, Canada.
J Biol Chem. 2002 Dec 6;277(49):47106-13. doi: 10.1074/jbc.M203289200. Epub 2002 Oct 4.
Utrophin is a component of the platelet membrane cytoskeleton and participates in cytoskeletal reorganization (Earnest, J. P., Santos, G. F., Zuerbig, S., and Fox, J. E. B. (1995) J. Biol. Chem. 270, 27259-27265). Although platelets do not contain dystrophin, the identification of smaller C-terminal isoforms of dystrophin, including Dp71, which are expressed in a wide range of nonmuscle tissues and cell lines, has not been investigated. In this report, we have identified Dp71 protein variants of 55-60 kDa (designated Dp71Delta(110)) in the membrane cytoskeleton of human platelets. Both Dp71Delta(110) and utrophin sediment from lysed platelets along with the high speed detergent-insoluble pellet, which contains components of the membrane cytoskeleton. Like the membrane cytoskeletal proteins vinculin and spectrin, Dp71Delta(110) and utrophin redistributed from the high speed detergent-insoluble pellet to the integrin-rich low speed pellet of thrombin-stimulated platelets. Immunoelectron microscopy provided further evidence that Dp71Delta(110) was localized to the submembranous cytoskeleton. In addition to Dp71Delta(110), platelets contained several components of the dystrophin-associated protein complex, including beta-dystroglycan and syntrophin. To better understand the potential function of Dp71Delta(110), collagen adhesion assays were performed on platelets isolated from wild-type or Dp71-deficient (mdx(3cv)) mice. Adhesion to collagen in response to thrombin was significantly decreased in platelets isolated from mdx(3cv) mice, compared with wild-type platelets. Collectively, our results provide evidence that Dp71Delta(110) is a component of the platelet membrane cytoskeleton, is involved in cytoskeletal reorganization and/or signaling, and plays a role in thrombin-mediated platelet adhesion.
肌养蛋白是血小板膜细胞骨架的一个组成部分，参与细胞骨架的重组（欧内斯特，J.P.，桑托斯，G.F.，祖尔比希，S.，以及福克斯，J.E.B.（1995年）《生物化学杂志》270卷，27259 - 27265页）。虽然血小板不含抗肌萎缩蛋白，但抗肌萎缩蛋白较小的C末端异构体，包括在多种非肌肉组织和细胞系中表达的Dp71，尚未得到研究。在本报告中，我们在人血小板的膜细胞骨架中鉴定出了55 - 60 kDa的Dp71蛋白变体（命名为Dp71Delta(110)）。Dp71Delta(110)和肌养蛋白与含有膜细胞骨架成分的高速去污剂不溶性沉淀一起，从裂解的血小板中沉降下来。与膜细胞骨架蛋白纽蛋白和血影蛋白一样，Dp71Delta(110)和肌养蛋白从高速去污剂不溶性沉淀重新分布到凝血酶刺激血小板的富含整合素的低速沉淀中。免疫电子显微镜提供了进一步的证据，表明Dp71Delta(110)定位于膜下细胞骨架。除了Dp71Delta(110)，血小板还含有抗肌萎缩蛋白相关蛋白复合物的几种成分，包括β - 肌营养不良聚糖和肌萎缩蛋白结合蛋白。为了更好地理解Dp71Delta(110)的潜在功能，对从野生型或Dp71缺陷型（mdx(3cv)）小鼠分离的血小板进行了胶原黏附试验。与野生型血小板相比，从mdx(3cv)小鼠分离的血小板对凝血酶刺激的胶原黏附显著降低。总的来说，我们的结果提供了证据，表明Dp71Delta(110)是血小板膜细胞骨架的一个组成部分，参与细胞骨架重组和/或信号传导，并在凝血酶介导的血小板黏附中起作用。
