The tyrosine phosphatase SHP-2 is required for mediating phosphatidylinositol 3-kinase/Akt activation by growth factors
The tyrosine phosphatase SHP-2 is required for mediating phosphatidylinositol 3-kinase/Akt activation by growth factors
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DOI：
10.1038/sj.onc.1204699
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发表时间：
2001-09-20
期刊：
影响因子：
8
通讯作者：
Greene, MI
中科院分区：
文献类型：
--
作者：
Wu, CJ;O'Rourke, DM;Greene, MI
SHP-2是一种普遍表达的具有两个SH2结构域的非跨膜酪氨酸磷酸酶。多项反向遗传学研究表明，SHP-2是器官和动物发育所必需的成分。以野生型和纯合型SH2结构域缺失的小鼠成纤维细胞为研究对象，研究了SHP-2对生长因子激活磷脂酰肌醇3-激酶(PI3K)的调节作用。此外，将SHP-2和各种突变体分别导入人胶质母细胞瘤细胞和SHP-2(-/-)小鼠成纤维细胞。我们发现，EGF刺激和EGFR癌蛋白(Delta EGFR)的表达独立地诱导了PI3K的P85亚单位与SHP-2的免疫共沉淀。靶向缺失SHP-2的N端SH2结构域严重损害了PDGF和IGF诱导的Akt磷酸化。SHP-2在U87 MG胶质母细胞瘤细胞中的异位表达增强了EGF诱导的Akt磷酸化，其作用可被其N端SH2结构域的突变所抵消。同样，SHP-2(-/-)细胞中SHP-2表达的重建增强了EGF诱导的Akt磷酸化，而挽救了PDGF和IGF诱导的Akt磷酸化。进一步的脂蛋白激酶活性分析证实，SHP-2对Akt磷酸化的调节与其对PI3K激活的调节有关。根据这些结果，我们得出结论，SHP-2是介导PI3K/Akt激活所必需的，而N端SH2结构域对于SHP-2在调节PI3K途径激活中的正向作用至关重要。
SHP-2 is a ubiquitously expressed non-transmembrane tyrosine phosphatase with two SH2 domains. Multiple reverse-genetic studies have indicated that SHP-2 is a required component for organ and animal development. SHP-2 wild-type and homozygous mutant mouse fibroblast cells in which the N-terminal SH2 domain was target-deleted were used to examine the function of SHP-2 in regulating Phosphatidylinositol 3-Kinase (PI3K) activation by growth factors. In addition, SHP-2 and various mutants were introduced into human glioblastoma cells as well as SHP-2(-/-) mouse fibroblasts. We found that EGF stimulation and EGFR oncoprotein (Delta EGFR) expression independently induced the co-immunoprecipitation of the p85 subunit of PI3K with SHP-2. Targeted deletion of the N-terminal SH2 domain of SHP-2 severely impaired PDGF- and IGF-induced Akt phosphorylation. Ectopic expression of SHP-2 in U87MG gliobastoma cells elevated EGF-induced Akt phosphorylation, and the effect was abolished by mutation of its N-terminal SH2 domain. Likewise, the reconstitution of SHP-2 expression in the SHP-2(-/-) cells enhanced Akt phosphorylation induced by EGF while rescuing that induced by PDGF and IGF. Further lipid kinase activity assays confirmed that SHP-2 modulation of Akt phosphorylation correlated with its regulation of PI3K activation. Based on these results, we conclude that SHP-2 is required for mediating PI3K/Akt activation, and the N-terminal SH2 domain is critically important for a 'positive' role of SHP-2 in regulating PI3K pathway activation.