p120(cbl) is a cytosolic adapter protein that associates with phosphoinositide 3-kinase in response to epidermal growth factor in PC12 and other cells
p120(cbl) is a cytosolic adapter protein that associates with phosphoinositide 3-kinase in response to epidermal growth factor in PC12 and other cells
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DOI：
10.1074/jbc.271.1.563
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发表时间：
1996-01-05
影响因子：
4.8
通讯作者：
Cantley, LC
中科院分区：
文献类型：
--
作者：
Soltoff, SP;Cantley, LC
虽然表皮生长因子（EGF）激活磷脂酰肌醇（PI）3-激酶的活性在许多类型的细胞或细胞系，在大多数情况下，我们已经研究了PI 3-激酶的p85调节亚基似乎不直接结合到EGF受体。以前，我们证明，表皮生长因子依赖的PI 3-激酶活性在A431细胞中的激活是伴随着结合的p85的ErbB 3，表皮生长因子受体同源物。然而，这一机制并不能解释PI 3-激酶活性的大激活，这是在PC 12和A549细胞中发现的，它们几乎没有或没有ErbB 3。在这里，我们提供的证据表明，p120（cbl）原癌蛋白是一种细胞内的衔接蛋白，与PI 3-激酶，从而参与EGF依赖性激活这种酶在这两个细胞系。使用抗p120（cbl）抗体，我们免疫沉淀EGF受体从PC 12细胞和PI 3-激酶活性从PC 12和A549细胞中的EGF依赖的方式。用神经生长因子或胰岛素处理PC 12细胞可刺激PI 3-激酶活性的大量增加，这种活性用抗Tyr（P）抗体免疫沉淀，但用抗p120（cbl）抗体则不能。在EGF处理的PC 12细胞中，p120（cbl）的酪氨酸磷酸化显示出与PI 3-激酶激活相似的动力学，这通过使用抗p120（cbl）和抗Tyr（P）免疫沉淀物进行的体内脂质产生和脂质激酶测定来测量。利用p85不同结构域的谷胱甘肽S-转移酶融合蛋白证明，与p85的SH 2和SH 3结构域结合的p120（cbl）也存在于A431细胞中，并提供了EGF激活这些细胞中PI 3-激酶的额外途径。
Although epidermal growth factor (EGF) activates phosphoinositide (PI) 3-kinase activity in a number of types of cells or cell lines, in most cases that we have investigated the p85 regulatory subunit of PI 3-kinase does not appear to bind directly to the EGF receptor. Previously we demonstrated that EGF dependent activation of PI 3-kinase activity in A431 cells is accompanied by the binding of p85 to ErbB3, an EGF receptor homologue. However, this mechanism did not explain the large activation of PI 3-kinase activity that was found in PC12 and A549 cells, which possess little or no ErbB3. Here we provide evidence that the p120(cbl) protooncoprotein is an intracellular adapter protein that associates with PI 3-kinase and thus is involved in the EGF-dependent activation of this enzyme in these two cell lines. Using an anti-p120(cbl) antibody, we immunoprecipitated the EGF receptor from PC12 cells and PI 3-kinase activity from PC12 and A549 cells in an EGF-dependent fashion. Treatment of PC12 cells with nerve growth factor or insulin stimulated large increases in PI 3-kinase activity that was immunoprecipitated using anti-Tyr(P) antibody but not using anti p120(cbl) antibody. In EGF-treated PC12 cells, the tyrosine phosphorylation of p120(cbl) displayed similar kinetics to the activation of PI 3-kinase as measured by both in vivo lipid production and lipid kinase assays conducted using anti-p120(cbl) and anti-Tyr(P) immunoprecipitates. The use of glutathione S-transferase fusion proteins of various domains of p85 demonstrated that p120(cbl) associated with both the SH2 and SH3 domains of p85, p120(cbl) was also present in A431 cells and offers an additional pathway by which EGF can activate PI 3-kinase in these cells.