He T C, Jiang N, Zhuang H, Wojchowski D M
Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park 16802, USA.
J Biol Chem. 1995 May 12;270(19):11055-61. doi: 10.1074/jbc.270.19.11055.
Based on the recently implicated role of Shc as a signaling effector for type I cytokine receptors, factors which mediate the recruitment and phosphorylation of Shc in the erythropoietin receptor (EPOR) system have been studied. FDC-P1 cells stably expressing the wild type murine EPOR supported the EPO-induced association of Shc with Jak2 and its rapid tyrosine phosphorylation. However, this did not depend upon the presence of phosphotyrosine sites within the EPOR and was mediated by a mitogenically deficient receptor form (EPOR329) lacking cytoplasmic tyrosine residues. This was shown both by Western blotting of Shc and Jak2 co-immunoprecipitates and through the development of an in vitro assay for cytokine-induced Shc phosphorylation. The direct association of Shc with Jak2 also was observed and was shown to depend upon EPO-exposure and the SH2 subdomain of Shc. Together, these studies indicate that Jak2, in part, may mediate the EPO-induced phosphorylation of Shc.
基于Shc最近被认为是I型细胞因子受体的信号转导效应器这一作用，人们对介导红细胞生成素受体（EPOR）系统中Shc募集和磷酸化的因子进行了研究。稳定表达野生型小鼠EPOR的FDC-P1细胞支持EPO诱导的Shc与Jak2的结合及其快速酪氨酸磷酸化。然而，这并不依赖于EPOR内磷酸酪氨酸位点的存在，而是由缺乏细胞质酪氨酸残基的有丝分裂缺陷型受体形式（EPOR329）介导的。这通过Shc和Jak2共免疫沉淀的蛋白质印迹以及通过开发一种用于细胞因子诱导的Shc磷酸化的体外测定法得以证明。还观察到Shc与Jak2的直接结合，并表明其依赖于EPO暴露和Shc的SH2亚结构域。总之，这些研究表明Jak2可能部分介导EPO诱导的Shc磷酸化。
