Rho mediates endocytosis of epidermal growth factor receptor through phosphorylation of endophilin A1 by Rho-kinase
Rho mediates endocytosis of epidermal growth factor receptor through phosphorylation of endophilin A1 by Rho-kinase
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DOI：
10.1111/j.1365-2443.2005.00895.x
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发表时间：
2005-10-01
期刊：
影响因子：
2.1
通讯作者：
Kaibuchi, K
中科院分区：
文献类型：
--
作者：
Kaneko, T;Maeda, A;Kaibuchi, K
表皮生长因子（EGF）结合后，表皮生长因子受体被激活，通过内吞作用内化，随后通过溶酶体途径降解。活化的EGF受体的内吞运输对于控制EGF信号传导至关重要。在配体诱导的EGF受体激活后，Cbl（泛素连接酶）与激活的受体结合，并导致激活的EGF受体附近的CIN85 （85 kDa的Cbl相互作用蛋白）/嗜内啡肽复合物易位。内啡肽被认为是网格蛋白介导的内吞作用的关键调节因子，而内啡肽在活性EGF受体附近的易位被认为可以促进受体内化。小GTPase Rho的组成型活性突变体抑制EGF受体内吞作用。在这项研究中，我们发现这种抑制作用被Rho相关激酶（Rho激酶）的显性阴性形式所抵消，Rho相关激酶是Rho的一种效应。为了阐明Rho/Rho激酶信号下游的内吞作用的分子机制，我们寻找并鉴定了作为Rho激酶新底物的嗜内蛋白A1。我们确定了亲内生蛋白A1在Thr-14的磷酸化位点，并制成了亲内生蛋白T14D（用Asp取代Thr-14），有望模拟亲内生蛋白A1的磷酸化状态。嗜内啡肽T14D抑制EGF受体内化。此外，rho激酶磷酸化的嗜内肽抑制了与CIN85的结合。综上所述，这些结果表明Rho激酶磷酸化Rho下游的嗜内蛋白，并通过抑制嗜内蛋白与CIN85的结合来调节EGF受体的内吞作用。
After binding of epidermal growth factor (EGF), the EGF receptor is activated, internalized by endocytosis, and subsequently degraded in the lysosomal pathway. Endocytotic trafficking of the activated EGF receptor is essential for controlling EGF signaling. Upon ligand-induced activation of EGF receptors, Cbl (ubiquitin ligase) binds to the activated receptor and leads to translocation of the CIN85 (Cbl-interacting protein of 85 kDa)/endophilin complex in the vicinity of the activated EGF receptors. Endophilin is known as a key regulator of clathrin-mediated endocytosis, and the translocation of endophilin in the vicinity of active EGF receptor is thought to promote receptor internalization. The constitutively active mutant of small GTPase Rho inhibits EGF receptor endocytosis. In this study, we found that this inhibitory effect was canceled by the dominant negative form of Rho-associated kinase (Rho-kinase), which is an effector of Rho. To clarify the molecular mechanisms of endocytosis downstream of Rho/Rho-kinase signal, we searched for and identified endophilin A1 as a novel substrate of Rho-kinase. We identified the phosphorylation site of endophilin A1 at Thr-14 and made endophilin T14D (substitution of Thr-14 by Asp), which is expected to mimic the phosphorylation state of endophilin A1. Endophilin T14D inhibited EGF receptor internalization. Furthermore, phosphorylation of endophilin by Rho-kinase inhibited the binding to CIN85. Taken together, these results suggest that Rho-kinase phosphorylates endophilin downstream of Rho and regulates EGF receptor endocytosis through the inhibition of binding between endophilin and CIN85.