Adaptor protein APPL1 interacts with EGFR to orchestrate EGF-stimulated signaling

信号转导枢纽蛋白APPL1调控表皮生长因子信号轴机制研究(英文)

Epidermal growth factor receptor(EGFR)mediates multiple signaling pathways that regulate cell migration, proliferation, and differentiation. Adaptor protein APPL1 has been reported to function as a downstream effector of EGFR signaling pathway. However, molecular mechanisms underlying the role of APPL1 downstream of EGFR signaling remains elusive. Here, we identified APPL1 as a critical molecule that interacts with EGFR.Suppression of APPL1 by si RNA inhibited EGF-stimulated Akt phosphorylation. Functionally, EGF stimulation of cells caused phosphorylation of APPL1 at Ser636, which subsequently promoted the interaction between APPL1 and EGFR, indicating that APPL1 sensitizes EGF stimulation by acting at a site downstream of the EGFR signaling.Importantly, non-phosphorylatable mutant of APPL1 reduced cell migration compared with wild-type APPL1 in an Akt-dependent manner. Our study reveals a novel function of APPL1 in EGF signaling and defines a novel molecular mechanism by which phosphorylation of APPL1 upon EGF stimulation regulates cell migration underlying EGF-stimulated Akt pathway.

表皮生长因子信号轴调控细胞可塑性与命运决定等重要细胞生理学过程,但细胞信号转导枢纽蛋白APPL1如何介导表皮生长因子信号轴在细胞迁移过程中的分子机制仍不甚清晰.我们在本项研究中鉴定出APPL1是一个新的表皮生长因子受体结合蛋白并调控表皮生长因子介导的细胞定向迁移活动.利用RNA干扰技术,我们发现:在细胞中敲低APPL1可下调EGF介导的Akt和GSK3β的磷酸化水平.进一步解析发现,EGF刺激会引起APPL1第636位丝氨酸的磷酸化,进而增强APPL1与表皮生长因子受体的结合力.通过转入模拟磷酸化及不可被磷酸化的APPL1突变体,我们发现抑制APPL1第636位丝氨酸的磷酸化可阻碍表皮生长因子介导的细胞迁移活动.我们认为,APPL1蛋白通过第636位丝氨酸的磷酸化增强其与表皮生长因子受体的结合及其在细胞质膜上的稳定性,从而延续表皮生长因子信号轴的活性并有效调控细胞的定向迁移活动.