Groysman M, Nagano M, Shaanan B, Katzav S
The Hubert H. Humphrey Center for Experimental Medicine and Cancer Research, The Hebrew University, Hadassah Medical School, Jerusalem, Israel.
Oncogene. 1998 Sep 24;17(12):1597-606. doi: 10.1038/sj.onc.1202074.
The vav proto-oncogene encodes a protein with multiple modulae domains that enable it to function as a mediator, linking tyrosine signaling to downstream events in hematopoietic cells. Circumstantial evidence suggests that protein-protein interactions exerted by two of these domains, the Src homology 2 (SH2) and the Src homology 3 (SH3), play an important role in the regulation of Vav activity. To study the relevance of the SH3 domain for the function of vav as a transforming gene, we have created several mutations in the SH3 domain located at its carboxy region. Substitution of the non-conserved aspartic acid 797 (to asparagine, D797N) retained the transforming potential of the vav oncogene, whereas substitutions of five highly conserved amino-acids: alanine 789 (to asparagine, A789N), leucine 801 (to arginine, L801R), tryptophan 821 (to arginine, W821R), glycine 830 (to valine, G830V) and valine 837 (to glutamic acid, V837E) greatly reduced its transforming potential. The mutant proteins resemble Vav in many biochemical properties; however, while the transforming mutant protein (D797N) associates with several unidentified proteins in a manner similar to that of Vav, the non-transforming mutant Vav proteins react very poorly with these proteins. Among the known Vav-interacting proteins, hnRNP-K associates with all mutant proteins except A789N and V837E whereas binding of Zyxin to any of the mutant proteins is not affected. Taken together, our results clearly demonstrate that the SH3 domain has a positive effect on vav activity and is needed for vav transformation. The vavSH3C associating protein(s) that are crucial for its activity as a transforming gene have probably not yet been identified.
vav原癌基因编码一种具有多个调节结构域的蛋白质，使其能够作为一种介质发挥作用，将酪氨酸信号传导与造血细胞中的下游事件联系起来。间接证据表明，由其中两个结构域，即Src同源2（SH2）和Src同源3（SH3）所产生的蛋白质-蛋白质相互作用，在Vav活性的调节中起重要作用。为了研究SH3结构域与vav作为转化基因功能的相关性，我们在位于其羧基区域的SH3结构域中产生了几个突变。非保守天冬氨酸797被替换为天冬酰胺（D797N）保留了vav癌基因的转化潜力，而五个高度保守氨基酸的替换：丙氨酸789（被替换为天冬酰胺，A789N）、亮氨酸801（被替换为精氨酸，L801R）、色氨酸821（被替换为精氨酸，W821R）、甘氨酸830（被替换为缬氨酸，G830V）和缬氨酸837（被替换为谷氨酸，V837E）大大降低了其转化潜力。突变蛋白在许多生化特性上类似于Vav；然而，虽然转化突变蛋白（D797N）以与Vav相似的方式与几种未鉴定的蛋白质结合，但非转化突变Vav蛋白与这些蛋白质的反应非常弱。在已知的与Vav相互作用的蛋白质中，hnRNP-K与除A789N和V837E之外的所有突变蛋白结合，而斑联蛋白与任何突变蛋白的结合不受影响。综上所述，我们的结果清楚地表明，SH3结构域对vav活性有积极影响，并且是vav转化所必需的。作为转化基因发挥其活性所必需的vavSH3C相关蛋白可能尚未被鉴定出来。
