Choi Jang Hyun, Bae Sun Sik, Park Jong Bae, Ha Sang Hoon, Song Hebok, Kim Jae-Ho, Cocco Lucio, Ryu Sung Ho, Suh Pann-Ghill
Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea.
Mol Cells. 2003 Apr 30;15(2):245-55.
Phospholipase C-gamma1 (PLC-gamma1) plays pivotal roles in cellular growth and proliferation through its two Src homology (SH) 2 domains and its single SH3 domain, which interact with signaling molecules in response to various growth factors and hormones. However, the role of the SH domains in the growth factor-induced regulation of PLC-gamma1 is unclear. By peptide-mass fingerprinting analysis we have identified Cbl as a binding protein for the SH3 domain of PLC-gamma1 from rat pheochromatocyte PC12 cells. Association of Cbl with PLC-gamma1 was induced by epidermal growth factor (EGF) but not by nerve growth factor (NGF). Upon EGF stimulation, both Cbl and PLC-gamma1 were recruited to the activated EGF receptor through their SH2 domains. Mutation of the SH2 domains of either Cbl or PLC-gamma1 abrogated the EGF-induced interaction of PLC-gamma1 with Cbl, indicating that SH2-mediated translocation is essential for the association of PLC-gamma1 and Cbl. Overexpression of Cbl attenuated EGF-induced tyrosine phosphorylation and the subsequent activation of PLC-gamma1 by interfering competitively with the interaction between PLC-gamma1 and EGFR. Taken together, these results provide the first indications that Cbl may be a negative regulator of intracellular signaling following EGF-induced PLC-gamma1 activation.
磷脂酶C-γ1（PLC-γ1）通过其两个Src同源（SH）2结构域和单个SH3结构域在细胞生长和增殖中发挥关键作用，这些结构域可响应各种生长因子和激素与信号分子相互作用。然而SH结构域在生长因子诱导的PLC-γ1调节中的作用尚不清楚。通过肽质量指纹图谱分析，我们已鉴定出Cbl是大鼠嗜铬细胞瘤PC12细胞中PLC-γ1的SH3结构域的结合蛋白。Cbl与PLC-γ1的结合是由表皮生长因子（EGF）诱导的，而不是由神经生长因子（NGF）诱导的。在EGF刺激下，Cbl和PLC-γ1都通过它们的SH2结构域被募集到活化的EGF受体上。Cbl或PLC-γ1的SH2结构域的突变消除了EGF诱导的PLC-γ1与Cbl的相互作用，表明SH2介导的易位对于PLC-γ1和Cbl的结合至关重要。Cbl的过表达通过竞争性干扰PLC-γ1与EGFR之间的相互作用减弱了EGF诱导的酪氨酸磷酸化以及随后PLC-γ1的激活。综上所述，这些结果首次表明Cbl可能是EGF诱导的PLC-γ1激活后细胞内信号传导的负调节因子。
