Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto M5G 1X5, Canada.
Nature. 2013 Jul 11;499(7457):166-71. doi: 10.1038/nature12308.
Cell-surface receptors frequently use scaffold proteins to recruit cytoplasmic targets, but the rationale for this is uncertain. Activated receptor tyrosine kinases, for example, engage scaffolds such as Shc1 that contain phosphotyrosine (pTyr)-binding (PTB) domains. Using quantitative mass spectrometry, here we show that mammalian Shc1 responds to epidermal growth factor (EGF) stimulation through multiple waves of distinct phosphorylation events and protein interactions. After stimulation, Shc1 rapidly binds a group of proteins that activate pro-mitogenic or survival pathways dependent on recruitment of the Grb2 adaptor to Shc1 pTyr sites. Akt-mediated feedback phosphorylation of Shc1 Ser 29 then recruits the Ptpn12 tyrosine phosphatase. This is followed by a sub-network of proteins involved in cytoskeletal reorganization, trafficking and signal termination that binds Shc1 with delayed kinetics, largely through the SgK269 pseudokinase/adaptor protein. Ptpn12 acts as a switch to convert Shc1 from pTyr/Grb2-based signalling to SgK269-mediated pathways that regulate cell invasion and morphogenesis. The Shc1 scaffold therefore directs the temporal flow of signalling information after EGF stimulation.
细胞表面受体通常利用支架蛋白来招募细胞质靶标,但这种做法的原理尚不清楚。例如,激活的受体酪氨酸激酶会与 Shc1 等支架结合,Shc1 含有磷酸酪氨酸 (pTyr) 结合 (PTB) 结构域。在这里,我们使用定量质谱法表明,哺乳动物 Shc1 通过多波不同的磷酸化事件和蛋白质相互作用对表皮生长因子 (EGF) 刺激做出反应。刺激后,Shc1 迅速与一组激活促有丝分裂或存活途径的蛋白质结合,这取决于 Grb2 衔接蛋白与 Shc1 pTyr 位点的募集。然后,Akt 介导的 Shc1 Ser 29 反馈磷酸化招募 Ptpn12 酪氨酸磷酸酶。随后是一组参与细胞骨架重排、运输和信号终止的蛋白质亚网络,它们以延迟的动力学与 Shc1 结合,主要通过 SgK269 假激酶/衔接蛋白。Ptpn12 充当开关,将 Shc1 从基于 pTyr/Grb2 的信号转导转换为 SgK269 介导的途径,从而调节细胞侵袭和形态发生。因此,Shc1 支架在 EGF 刺激后指导信号信息的时间流。
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