Epidermal growth factor-stimulated tyrosine phosphorylation of caveolin-1 - Enhanced caveolin-1 tyrosine phosphorylation following aberrant epidermal, growth factor receptor status
Epidermal growth factor-stimulated tyrosine phosphorylation of caveolin-1 - Enhanced caveolin-1 tyrosine phosphorylation following aberrant epidermal, growth factor receptor status
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DOI：
10.1074/jbc.275.11.7481
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发表时间：
2000-03-17
影响因子：
4.8
通讯作者：
Bertics, PJ
中科院分区：
文献类型：
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作者：
Kim, YN;Wiepz, GJ;Bertics, PJ
小窝蛋白-1是小窝的主要外壳蛋白，已被报道与包括表皮生长因子受体在内的多种细胞内信号分子相互作用。为了研究小窝蛋白-1在EGF受体作用中的作用，我们利用转基因的小鼠B82L成纤维细胞：(A)野生型EGF受体，(B)1022位C端截短的EGF受体，(C)973位的C端截短的EGF受体，或(D)无活性的EGF受体(R721M)。在EGF处理后，表达截短型EGF受体的细胞中的小窝蛋白-1的凝胶迁移率发生了明显的变化，但在野生型EGF受体的正常水平或激酶失活受体的细胞中都没有检测到这种变化。在加入其他细胞刺激，如血小板衍生生长因子、胰岛素、碱性成纤维细胞生长因子或佛波酯13-醋酸酯后，也没有观察到这种迁移率的变化。对EGF刺激或非刺激细胞的小窝蛋白-1免疫沉淀物的分析表明，在表达截短的EGF受体的细胞中，EGF诱导的小窝蛋白-1的迁移率改变与其酪氨酸磷酸化有关，在10 nm EGF作用后5分钟内达到最大的小窝蛋白-1磷酸化并保持升高至少2小时。此外，几种不同的含磷酸酪氨酸的蛋白(60，45，29，24，和20 kDa)以EGF依赖的方式与小窝蛋白-1免疫共沉淀。此外，Src家族激酶抑制剂PP1不影响受体的自磷酸化，但它确实抑制EGF诱导的小窝蛋白-1的迁移率变化和磷酸化。相反，MEK抑制剂PD98059和UO126可以减弱EGF诱导的丝裂原活化蛋白激酶的激活，但不影响EGF诱导的小窝蛋白-1的迁移率变化。由于EGF受体的截短和过表达与细胞转化有关，这些结果首次证明小窝蛋白-1的酪氨酸磷酸化是通过EGF敏感的信号通路发生的，该信号通路可以被各种形式的EGF受体的异常活性或表达所增强。
Caveolin-1 is the major coat protein of caveolae and has been reported to interact with various intracellular signaling molecules including the epidermal growth factor (EGF) receptor. To investigate the involvement of caveolin-1 in EGF receptor action, we used mouse B82L fibroblasts transfected with (a) wild type EGF receptor, (b) a C-terminally truncated EGF receptor at residue 1022, (c) a C-terminally truncated EGF receptor at residue 973, or (d) a kinase-inactive EGF receptor (R721M). Following EGF treatment, there was a distinct electrophoretic mobility shift of the caveolin-1 present in cells expressing the truncated forms of the EGF receptor, but this shift was not detectable in cells bearing either normal levels of the wild type EGF receptor or a kinase-inactive receptor. This mobility shift wins also not observed following the addition of other cell stimuli, such as platelet-derived growth factor, insulin, basic fibroblast growth factor, or phorbol 12-myristate 13-acetate, Analysis of caveolin-1 immunoprecipitates from EGF-stimulated or nonstimulated cells demonstrated that the EGF-induced mobility shift of caveolin-1 was associated with its tyrosine phosphorylation in cells expressing truncated EGF receptors, Maximal caveolin-1 phosphorylation was achieved within 5 min after exposure to 10 nm EGF and remained elevated for at least 2 h. Additionally, several distinct phosphotyrosine-containing proteins (60, 45, 29, 24, and 20 kDa) were co-immunoprecipitated with caveolin-1 in an EGF-dependent Manner. Furthermore, the Src family kinase inhibitor, PP1, does not affect autophosphorylation of the receptor, but it does inhibit the EGF-induced mobility shift and phosphorylation of caveolin-1. Conversely, the MEK inhibitors PD98059 and UO126 could attenuate EGF-induced mitogen-activated protein kinase activation, they do not affect the EGF-induced mobility shift of caveolin-1. Because truncation and overexpression of the EGF receptor have been linked to cell transformation, these results provide the first evidence that the tyrosine phosphorylation of caveolin-1 occurs via an EGF-sensitive signaling pathway that can be potentiated by an aberrant activity or expression of various forms of the EGF receptor.