Kiyokawa E, Hashimoto Y, Kurata T, Sugimura H, Matsuda M
Department of Pathology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8840, Japan.
J Biol Chem. 1998 Sep 18;273(38):24479-84. doi: 10.1074/jbc.273.38.24479.
DOCK180 is one of the two principal proteins bound to the SH3 domain of the adaptor protein CrkII. Here, we have studied the involvement of DOCK180 in integrin signaling. DOCK180 was neither phosphorylated nor bound to CrkII in quiescent NIH 3T3 cells and 3Y1 cells. We found that DOCK180 was phosphorylated and bound to CrkII in NIH 3T3 cells stimulated with integrin and also in 3Y1 cells transformed by v-src or v-crk. The binding of DOCK180 to CrkII correlated with the binding of CrkII to p130(Cas), which is a major CrkII SH2 domain-binding protein at focal adhesions. In a reconstitution experiment, expression of DOCK180 induced hyperphosphorylation of p130(Cas) and a concomitant increase in the amount of CrkII bound to p130(Cas). Similarly, binding of DOCK180 to CrkII was also enhanced by the coexpression of p130(Cas). Finally, we found that coexpression of p130(Cas) and CrkII with DOCK180 induced local membrane spreading and accumulation of DOCK180-CrkII-p130(Cas) complexes at focal adhesions. These findings suggest that DOCK180 positively regulates signaling from integrins to CrkII-p130(Cas) complexes at focal adhesions.
DOCK180是与衔接蛋白CrkII的SH3结构域结合的两种主要蛋白质之一。在此，我们研究了DOCK180在整合素信号传导中的作用。在静止的NIH 3T3细胞和3Y1细胞中，DOCK180既不被磷酸化，也不与CrkII结合。我们发现，在用整合素刺激的NIH 3T3细胞以及被v-src或v-crk转化的3Y1细胞中，DOCK180被磷酸化并与CrkII结合。DOCK180与CrkII的结合与CrkII与p130（Cas）的结合相关，p130（Cas）是粘着斑处主要的CrkII SH2结构域结合蛋白。在重构实验中，DOCK180的表达诱导p130（Cas）的过度磷酸化，并伴随与p130（Cas）结合的CrkII量的增加。同样，p130（Cas）的共表达也增强了DOCK180与CrkII的结合。最后，我们发现p130（Cas）、CrkII与DOCK180的共表达诱导局部膜伸展，并使DOCK180-CrkII-p130（Cas）复合物在粘着斑处积累。这些发现表明，DOCK180在粘着斑处正向调节从整合素到CrkII-p130（Cas）复合物的信号传导。
