RAB-10 Promotes EHBP-1 Bridging of Filamentous Actin and Tubular Recycling Endosomes.
RAB-10 Promotes EHBP-1 Bridging of Filamentous Actin and Tubular Recycling Endosomes.
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RAB-10 促进 EHBP-1 丝状肌动蛋白和管状回收内体的桥接。
DOI：
10.1371/journal.pgen.1006093
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发表时间：
2016-06
期刊：
影响因子：
4.5
通讯作者：
Grant BD
中科院分区：
文献类型：
--
作者：
Wang P;Liu H;Wang Y;Liu O;Zhang J;Gleason A;Yang Z;Wang H;Shi A;Grant BD
EHBP-1 (Ehbp1) 是内吞再循环的保守调节因子，充当包括 RAB-10 (Rab10) 在内的小 GTP 酶的效应子。在这里，我们提出证据表明 EHBP-1 通过 N 端 C2 样 (NT-C2) 结构域与管状内体磷脂酰肌醇-4,5-二磷酸 [PI(4,5)P2] 富集膜相关联，并定义了 NT-C2 结构域内介导膜相互作用的残基。此外，我们的结果表明，EHBP-1 中央钙调蛋白同源 (CH) 结构域在 RAB-10(GTP) 刺激的反应中与肌动蛋白微丝结合。线虫肠上皮中 RAB-10/EHBP-1 系统任何方面的缺失都会导致基底外侧回收货物保留在失去正常管状内体网络 (TEN) 组织的内体中。我们提出了一种机制，通过 RAB-10 促进内体结合的 EHBP-1 也与肌动蛋白细胞骨架结合的能力，从而促进内体管状形成。内体是细胞内细胞器，可对膜上不可或缺的蛋白质和脂质成分以及更松散相关的腔内容物进行分类，以递送到不同的细胞内目的地。与将货物回收回质膜相关的内体通常在形态上呈管状，并且这种形态被认为对于回收功能至关重要。我们之前的工作发现了一个特别引人注目的内体小管网络，参与线虫基底外侧肠上皮细胞的膜蛋白回收。我们随后对该系统中的基底外侧循环进行遗传分析，确定了这些内体的许多关键调节因子，包括小 GTP 酶 RAB-10 及其效应子 EHBP-1。我们在此提出的新工作表明，EHBP-1 通过将膜脂 PI(4,5)P2 连接到肌动蛋白细胞骨架来促进内体管化，并且 EHBP-1 与 RAB-10 的相互作用增强了 EHBP-1 与肌动蛋白的连接。这项工作对于所有细胞中内体管状结构如何发生具有广泛的意义，并且对于 EHBP-1 在相关过程中的作用具有特定的意义，例如胰岛素刺激的人类脂肪细胞中葡萄糖转运蛋白的循环，这一过程与 II 型糖尿病密切相关。
EHBP-1 (Ehbp1) is a conserved regulator of endocytic recycling, acting as an effector of small GTPases including RAB-10 (Rab10). Here we present evidence that EHBP-1 associates with tubular endosomal phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] enriched membranes through an N-terminal C2-like (NT-C2) domain, and define residues within the NT-C2 domain that mediate membrane interaction. Furthermore, our results indicate that the EHBP-1 central calponin homology (CH) domain binds to actin microfilaments in a reaction that is stimulated by RAB-10(GTP). Loss of any aspect of this RAB-10/EHBP-1 system in the C. elegans intestinal epithelium leads to retention of basolateral recycling cargo in endosomes that have lost their normal tubular endosomal network (TEN) organization. We propose a mechanism whereby RAB-10 promotes the ability of endosome-bound EHBP-1 to also bind to the actin cytoskeleton, thereby promoting endosomal tubulation. Endosomes are intracellular organelles that sort protein and lipid components integral to the membrane, as well as more loosely associated lumenal content, for delivery to distinct intracellular destinations. Endosomes associated with recycling cargo back to the plasma membrane are often tubular in morphology, and this morphology is thought to be essential for recycling function. Our previous work identified a particularly dramatic network of endosomal tubules involved in membrane protein recycling in the basolateral intestinal epithelial cells of C. elegans. Our subsequent genetic analysis of basolateral recycling in this system identified a number of key regulators of these endosomes, including the small GTPase RAB-10 and its effector EHBP-1. Our new work presented here shows that EHBP-1 promotes endosomal tubulation by linking the membrane lipid PI(4,5)P2 to the actin cytoskeleton, and that the linkage of EHBP-1 to actin is enhanced by the interaction of EHBP-1 with RAB-10. This work has broad implications for how endosomal tubulation occurs in all cells, and has specific implications for the role of EHBP-1 in related processes such as insulin-stimulated recycling of glucose transporters in human adipocytes, a process intimately linked to type II diabetes.