SH2-Bβ is a Rac-binding protein that regulates cell motility
SH2-Bβ is a Rac-binding protein that regulates cell motility
复制标题
DOI：
10.1074/jbc.m111138200
复制
发表时间：
2002-03-22
影响因子：
4.8
通讯作者：
Carter-Su, C
中科院分区：
文献类型：
--
作者：
Diakonova, M;Gunter, DR;Carter-Su, C
Src同源2 （SH2）结构域蛋白SH2- bbeta结合生长激素（GH）和细胞因子受体相关酪氨酸激酶JAK2的底物。SH2- β也通过其SH2结构域与多种激活的生长因子受体酪氨酸激酶结合。我们之前已经发现sh2 - β参与GH和血小板源性生长因子对肌动蛋白细胞骨架的调节。我们通过建立SH2-Bbeta对gh依赖性细胞运动的增强作用并定义这种增强所需的SH2-Bbeta区域来扩展这些发现。延时视频显微镜、吞噬动力学和/或损伤实验表明，由于点突变或c端截断，过度表达SH2- bbeta的细胞缺乏完整的SH2结构域，从而减少了细胞的运动。SH2- bbeta的n端富含脯氨酸结构域（氨基酸85-106）是抑制SH2结构域缺陷突变体细胞运动所必需的。共免疫沉淀实验表明Rac与该结构域结合。GH可激活内源性Rac， SH2-Bbeta显性负突变体可抑制组成活性Rac诱导的膜皱折。这些发现表明SH2-Bbeta是一种连接蛋白，通过招募Rac和潜在的Rac调节蛋白、Rac效应蛋白或其他肌动蛋白调节蛋白来激活细胞因子（如GH）和生长因子受体，从而促进肌动蛋白重排和细胞运动。
The Src homology 2 (SH2) domain-containing protein SH2-Bbeta binds to and is a substrate of the growth hormone (GH) and cytokine receptor-associated tyrosine kinase JAK2. SH2-Bbeta also binds, via its SH2 domain, to multiple activated growth factor receptor tyrosine kinases. We have previously implicated SH2-Bbeta in GH and platelet-derived growth factor regulation of the actin cytoskeleton. We extend these findings by establishing a potentiating effect of SH2-Bbeta on GH-dependent cell motility and defining regions of SH2-Bbeta required for this potentiation. Time-lapse video microscopy, phagokinetic, and/or wounding assays demonstrate reduced movement of cells overexpressing SH2-Bbeta lacking an intact SH2 domain because of a point mutation or a C-terminal truncation. An N-terminal proline-rich domain (amino acids 85-106) of SH2-Bbeta is required for inhibition of cellular motility by SH2 domain-deficient mutants. Co-immunoprecipitation experiments indicate that Rac binds to this domain. GH is shown to activate endogenous Rac, and dominant negative mutants of SH2-Bbeta are shown to inhibit membrane ruffling induced by constitutively active Rac. These findings suggest that SH2-Bbeta is an adapter protein that facilitates actin rearrangement and cellular motility by recruiting Rac and potentially Rac-regulating, Rac effector, or other actin-regulating proteins to activated cytokine (e.g. GH) and growth factor receptors.