Tyrosine phosphorylation of Grb2 by Bcr/Abl and epidermal growth factor receptor: a novel regulatory mechanism for tyrosine kinase signaling
Tyrosine phosphorylation of Grb2 by Bcr/Abl and epidermal growth factor receptor: a novel regulatory mechanism for tyrosine kinase signaling
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DOI：
10.1093/emboj/20.23.6793
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发表时间：
2001-12-03
期刊：
影响因子：
11.4
通讯作者：
Van Etten, RA
中科院分区：
文献类型：
--
作者：
Li, SG;Couvillon, AD;Van Etten, RA
生长因子受体结合蛋白2（Growth factor receptor-binding protein-2，Grb 2）是Bcr/Abl癌蛋白和生长因子介导的信号转导的关键蛋白，通过其Src同源结构域SH 2和SH 3起衔接蛋白的作用。我们发现，Grb 2酪氨酸磷酸化的细胞表达BCR/ABL和A431细胞与表皮生长因子（EGF）刺激。Bcr/Abl或EGF受体对Grb 2的磷酸化可降低其与Sos的结合，但不影响其与Bcr/Abl的结合。酪氨酸磷酸化位点Tyr 209位于Grb 2的C-末端SH 3结构域中，在体外，Tyr 209的磷酸化可消除SH 3结构域与富含脯氨酸的Sos肽的结合。在体内表达的Grb 2突变体，其中Tyr 209被改变为苯丙氨酸增强BCR/ABL诱导的ERK激活和成纤维细胞转化，并增强和延长Grb 2介导的激活Ras，丝裂原活化蛋白激酶和c-Jun N-末端激酶对EGF刺激的反应。这些结果表明，酪氨酸磷酸化的Grb 2是一种新的机制，下调酪氨酸激酶信号。
Growth factor receptor-binding protein-2 (Grb2) plays a key role in signal transduction initiated by Bcr/Abl oncoproteins and growth factors, functioning as an adaptor protein through its Src homology 2 and 3 (SH2 and SH3) domains. We found that Grb2 was tyrosine-phosphorylated in cells expressing BCR/ABL and in A431 cells stimulated with epidermal growth factor (EGF). Phosphorylation of Grb2 by Bcr/Abl or EGF receptor reduced its SH3-dependent binding to Sos in vivo, but not its SH2-dependent binding to Bcr/Abl. Tyr209 within the C-terminal SH3 domain of Grb2 was identified as one of the tyrosine phosphorylation sites, and phosphorylation of Tyr209 abolished the binding of the SH3 domain to a proline-rich Sos peptide in vitro. In vivo expression of a Grb2 mutant where Tyr209 was changed to phenylalanine enhanced BCR/ABL-induced ERK activation and fibroblast transformation, and potentiated and prolonged Grb2-mediated activation of Ras, mitogen-activated protein kinase and c-Jun N-terminal kinase in response to EGF stimulation. These results suggest that tyrosine phosphorylation of Grb2 is a novel mechanism of down-regulation of tyrosine kinase signaling.