Regulation of endocytic recycling by C-elegans Rab35 and its regulator RME-4, a coated-pit protein
Regulation of endocytic recycling by C-elegans Rab35 and its regulator RME-4, a coated-pit protein
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DOI：
10.1038/emboj.2008.54
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发表时间：
2008-04-23
期刊：
影响因子：
11.4
通讯作者：
Grant, Barth D.
中科院分区：
文献类型：
--
作者：
Sato, Miyuki;Sato, Ken;Grant, Barth D.
利用秀丽隐杆线虫遗传筛选，我们确定受体介导的内吞作用（RME）-4和RME-5/ RAB-35作为体内卵黄内吞作用的重要调节因子。在rme-4和rab-35突变体中，卵黄受体不像预期的那样在细胞膜上积累，而是从皮质内体中丢失受体并在分散的小泡中积累，这表明受体再循环的缺陷。与此一致，遗传测试表明RME-4和RAB-35在网格蛋白的下游、RAB-7的上游起作用，并与再循环调节剂RAB-11和RME-1协同作用。我们发现，RME-4是一个保守的DENN结构域蛋白结合RAB-35在其GDP负载的构象。GFP-RME-4也与AP-2物理相互作用，富集在网格蛋白包被的凹坑上，并且需要网格蛋白而不是RAB-5用于皮质缔合。GFP-RAB-35定位于质膜和早期内吞区室，但在rme-4突变体中从内体丢失。我们提出RME-4在包被的凹坑和/或囊泡上起作用以募集RAB-35，RAB-35反过来在内体中起作用以促进受体再循环。
Using Caenorhabditis elegans genetic screens, we identified receptor-mediated endocytosis (RME)-4 and RME-5/ RAB-35 as important regulators of yolk endocytosis in vivo. In rme-4 and rab-35 mutants, yolk receptors do not accumulate on the plasma membrane as would be expected in an internalization mutant, rather the receptors are lost from cortical endosomes and accumulate in dispersed small vesicles, suggesting a defect in receptor recycling. Consistent with this, genetic tests indicate the RME-4 and RAB-35 function downstream of clathrin, upstream of RAB-7, and act synergistically with recycling regulators RAB-11 and RME-1. We find that RME-4 is a conserved DENN domain protein that binds to RAB-35 in its GDP-loaded conformation. GFP-RME-4 also physically interacts with AP-2, is enriched on clathrin-coated pits, and requires clathrin but not RAB-5 for cortical association. GFP-RAB-35 localizes to the plasma membrane and early endocytic compartments but is lost from endosomes in rme-4 mutants. We propose that RME-4 functions on coated pits and/or vesicles to recruit RAB-35, which in turn functions in the endosome to promote receptor recycling.