Adapter protein SH2B1beta cross-links actin filaments and regulates actin cytoskeleton.
Adapter protein SH2B1beta cross-links actin filaments and regulates actin cytoskeleton.
复制标题
DOI：
10.1210/me.2008-0428
复制
发表时间：
2009-07
影响因子：
--
通讯作者：
Leah C. Rider;J. Tao;S. Snyder;Brittany N. Brinley;Jiayun Lu;M. Diakonova
中科院分区：
文献类型：
--
作者：
Leah C. Rider;J. Tao;S. Snyder;Brittany N. Brinley;Jiayun Lu;M. Diakonova
含有Src Homology 2(SH2)结构域的适配蛋白SH2B1beta在严重肥胖、瘦素和胰岛素抵抗以及不孕症中发挥作用。SH2B1beta最初被鉴定为Janus tyroine kinase2(JAK2)底物，它参与了细胞运动和GH和血小板衍生生长因子对肌动蛋白重排的调节。SH2B1beta也是李斯特氏菌基于肌动蛋白的最大运动能力所必需的。在这里，我们使用低速制粒试验和电子显微镜来证明SH2B1beta有两个肌动蛋白结合位点，并且它在体外使肌动蛋白细丝发生交叉连接。野生型SH2B1beta定位于细胞皱褶和丝状伪足，但缺失150-200位氨基酸(第一个肌动蛋白结合位点)导致该蛋白错误定位于丝状伪足顶端复合体，在那里它与血管扩张剂刺激的磷酸蛋白(VASP)共存。基于在Vasp缺失的MVD7(-/-)细胞中进行的研究，无论是否有绿色荧光蛋白-Vasp重组，我们得出的结论是，天然SH2B1beta的适当细胞内定位需要第一个SH2B1beta肌动蛋白结合位点和Vasp的存在。最后，我们发现两个SH2B1beta肌动蛋白结合域都是GH和催乳素诱导的最大细胞皱折所必需的。综上所述，这些结果表明SH2B1beta作为一种连接肌动蛋白细丝的适配蛋白发挥作用，导致对JAK2激活的细胞反应的调制。
The Src homology 2 (SH2) domain-containing adapter protein SH2B1beta plays a role in severe obesity, leptin and insulin resistance, and infertility. SH2B1beta was initially identified as a Janus tyrosine kinase 2 (JAK2) substrate, and it has been implicated in cell motility and regulation of the actin rearrangement in response to GH and platelet-derived growth factor. SH2B1beta is also required for maximal actin-based motility of Listeria. Here we have used a low-speed pelleting assay and electron microscopy to demonstrate that SH2B1beta has two actin-binding sites and that it cross-links actin filaments in vitro. Wild-type SH2B1beta localized to cell ruffles and along filopodia, but deletion of amino acids 150-200 (the first actin-binding site) led to mislocalization of the protein to filopodia tip complexes where it colocalized with vasodilator-stimulated phosphoprotein (VASP). Based on studies performed in VASP-deficient MVD7(-/-) cells, with or without green fluorescent protein-VASP reconstitution, we concluded that the proper intracellular localization of native SH2B1beta required the presence of the first SH2B1beta actin-binding site and VASP. Finally, we found that both SH2B1beta actin-binding domains were required for maximal GH- and prolactin-induced cell ruffling. Together, these results suggest that SH2B1beta functions as an adapter protein that cross-links actin filaments, leading to modulation of cellular responses in response to JAK2 activation.