Association of Bcr-Abl with the proto-oncogene Vav is implicated in activation of the Rac-1 pathway
Association of Bcr-Abl with the proto-oncogene Vav is implicated in activation of the Rac-1 pathway
复制标题
DOI：
10.1074/jbc.m112397200
复制
发表时间：
2002-04-05
影响因子：
4.8
通讯作者：
Duyster, J
中科院分区：
文献类型：
--
作者：
Bassermann, F;Jahn, T;Duyster, J
Vav是Rho/Rac家族的鸟嘌呤核苷酸交换因子，主要在造血细胞中表达，并参与细胞增殖和细胞骨架组织。致癌酪氨酸激酶Bcr-Abl已被证明激活Rac-1，这对于Bcr-Abl诱导的白血病发生是重要的。Matsuguchi等人先前的研究（Matsuguchi，T.，因霍恩河C.的方法，Carlesso，N.，徐，G.，德鲁克，B.，和Griffin，J. D.（1995）EMBO J. 14，257-265）描述了表达Bcr-Abl的Mo 7 e细胞中Vav的增强的磷酸化，但未能证明两种蛋白质的缔合。在这里，我们报告的Vav和Bcr-Abl在酵母中，在体外和体内之间的直接复合物的鉴定。此外，我们显示酪氨酸磷酸化的Vav的Bcr-Abl。突变分析表明，SH 2结构域和C-末端SH 3结构域以及四脯氨酸基序直接相邻的N-末端SH 3结构域的Vav是重要的建立这种磷酸化酪氨酸依赖的相互作用。通过共表达编码SH 3-SH 2-SH 3结构域的Vav C末端作为显性负性构建体来消除Bcr-Abl对Rac-1的激活。与野生型骨髓相比，Bcr-Abl转导的Vav基因敲除小鼠的原代骨髓在培养细胞转化试验中显示增殖减少。这些结果表明，Bcr-Abl利用Vav作为鸟嘌呤核苷酸交换因子，在涉及Vav C末端折叠机制的过程中激活Rac-1。考虑到Rac-1激活对Bcr-Abl介导的白血病发生的重要性，该机制可能对慢性髓性白血病的分子发病机制至关重要，并且对导致Rac-1激活的其他信号转导途径也很重要。
Vav is a guanine nucleotide exchange factor for the Rho/Rac family predominantly expressed in hematopoietic cells and implicated in cell proliferation and cytoskeletal organization. The oncogenic tyrosine kinase Bcr-Abl has been shown to activate Rac-1, which is important for Bcr-Abl induced leukemogenesis. Previous studies by Matsuguchi et al. (Matsuguchi, T., Inhorn, R. C., Carlesso, N., Xu, G., Druker, B., and Griffin, J. D. (1995) EMBO J. 14, 257-265) describe enhanced phosphorylation of Vav in Bcr-Abl-expressing Mo7e cells yet fail to demonstrate association of the two proteins. Here, we report the identification of a direct complex between Vav and Bcr-Abl in yeast, in vitro and in vivo. Furthermore, we show tyrosine phosphorylation of Vav by Bcr-Abl. Mutational analysis revealed that the SH2 domain and the C-terminal SH3 domain as well as a tetraproline motif directly adjacent to the N-terminal SH3 domain of Vav are important for establishing this phosphotyrosine dependent interaction. Activation of Rac-1 by Bcr-Abl was abrogated by co-expression of the Vav C terminus encoding the SH3-SH2-SH3 domains as a dominant-negative construct. Bcr-Abl transduced primary bone marrow from Vav knock-out mice showed reduced proliferation in a culture cell transformation assay compared with wild-type bone marrow. These results suggest, that Bcr-Abl utilizes Vav as a guanine nucleotide exchange factor to activate Rac-1 in a process that involves a folding mechanism of the Vav C terminus. Given the importance of Rac-1 activation for Bcr-Abl-mediated leukemogenesis, this mechanism may be crucial for the molecular pathogenesis of chronic myeloid leukemia and of importance for other signal transduction pathways leading to the activation of Rac-1.