Husson H, Mograbi B, Schmid-Antomarchi H, Fischer S, Rossi B
INSERM U364, Faculte de Medecine, Nice, France.
Oncogene. 1997 May 15;14(19):2331-8. doi: 10.1038/sj.onc.1201074.
Recently c-Cbl has been reported to be phosphorylated upon CSF-1 stimulation. The product of the c-cbl proto-oncogene (c-Cbl) is a 120 kDa protein harboring several docking sites for Src homology 2 (SH2) domain containing proteins and proline-rich regions that have been shown to allow its constitutive association with the SH3 domains of Grb2. We demonstrate here that CSF-1 exposure of stable transfectant CHO cells expressing the CSF-1 receptor induced the sustained tyrosine phosphorylation of c-Cbl and its subsequent association with Crk-II and the p85 kDa subunit of the PI 3-kinase, while it constitutively associates with Grb2. We demonstrate by in vitro experiments that these associations require the SH2 domain of Crk-II and both the C- and N-terminal SH2 domains of the p85 subunit of the PI 3-kinase. cCbl is the major PI 3-kinase-containing protein in c-Fms expressing CHO cells upon CSF-1 stimulation. Thus c-Cbl behaves as a core protein, allowing the formation of a quaternary complex including, Crk-II, PI 3-kinase and Grb2. We provide evidence that this multiprotein complex can interact with the tyrosine phosphorylated CSF-1 receptor through the unoccupied SH2 domain of Grb2.
最近有报道称，c-Cbl在集落刺激因子-1（CSF-1）刺激下会发生磷酸化。c-cbl原癌基因的产物（c-Cbl）是一种120 kDa的蛋白质，含有多个用于含Src同源2（SH2）结构域的蛋白质的对接位点以及富含脯氨酸的区域，这些区域已被证明可使其与Grb2的SH3结构域组成性结合。我们在此证明，表达CSF-1受体的稳定转染CHO细胞暴露于CSF-1会诱导c-Cbl的持续酪氨酸磷酸化及其随后与Crk-II和PI 3-激酶的85 kDa亚基结合，而它与Grb2组成性结合。我们通过体外实验证明，这些结合需要Crk-II的SH2结构域以及PI 3-激酶85 kDa亚基的C端和N端SH2结构域。在CSF-1刺激下，cCbl是表达c-Fms的CHO细胞中主要的含PI 3-激酶的蛋白质。因此，c-Cbl起着核心蛋白的作用，允许形成一个包含Crk-II、PI 3-激酶和Grb2的四聚体复合物。我们提供的证据表明，这种多蛋白复合物可以通过Grb2未被占据的SH2结构域与酪氨酸磷酸化的CSF-1受体相互作用。
