Interactions between EHD proteins and Rab11-FIP2: A role for EHD3 in early endosomal transport
Interactions between EHD proteins and Rab11-FIP2: A role for EHD3 in early endosomal transport
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DOI：
10.1091/mbc.e05-05-0466
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发表时间：
2006-01-01
影响因子：
3.3
通讯作者：
Caplan, S
中科院分区：
文献类型：
--
作者：
Naslavsky, N;Rahajeng, J;Caplan, S
Eps 15同源结构域（EHD）1通过控制内化分子从内吞再循环室（ERC）到质膜的出口来实现膜再循环，类似于Rab 11所述的作用。然而，Rab 11和EHD家族蛋白之间的物理或功能联系尚未得到证实，它们协调其调节活性的模式仍然未知。在这里，我们证明了EHD 1和EHD 3（最接近的EHD 1 parabolic），结合Rab 11效应Rab 11-FIP 2通过EH-NPF相互作用。EHD/Rab 11-FIP 2关联受EHD蛋白结合核苷酸的能力影响，Rab 11-FIP 2被募集到含EHD的膜。这些结果与EHD 1和Rab 11-FIP 2在调节ERC退出方面的协调作用一致。然而，由于EHD 3没有功能，因此其与Rab 11-FIP 2相互作用的意义仍不清楚。令人惊讶的是，EHD 3表达的丧失阻止了内化的转铁蛋白和早期内体蛋白向ERC的递送，这种作用不同于EHD 1敲低后所描述的作用。此外，Rab 11-FIP 2和内源性Rab 11的亚细胞定位在EHD 3敲除后发生改变，这两种蛋白质都不存在于ERC中并保留在细胞外周中。本文所呈现的结果促进了EHD蛋白和Rab 11-FIP 2在介导内吞再循环中的协调作用，并为EHD 3在早期内体至ERC转运中的功能提供了证据。
Eps15 homology domain (EHD) 1 enables membrane recycling by controlling the exit of internalized molecules from the endocytic recycling compartment (ERC) en route to the plasma membrane, similar to the role described for Rab11. However, no physical or functional connection between Rab11 and EHD-family proteins has been demonstrated yet, and the mode by which they coordinate their regulatory activity remains unknown. Here, we demonstrate that EHD1 and EHD3 (the closest EHD1 paralog), bind to the Rab11-effector Rab11-FIP2 via EH-NPF interactions. The EHD/Rab11-FIP2 associations are affected by the ability of the EHD proteins to bind nucleotides, and Rab11-FIP2 is recruited to EHD-containing membranes. These results are consistent with a coordinated role for EHD1 and Rab11-FIP2 in regulating exit from the ERC. However, because no function has been attributed to EHD3, the significance of its interaction with Rab11-FIP2 remained unclear. Surprisingly, loss of EHD3 expression prevented the delivery of internalized transferrin and early endosomal proteins to the ERC, an effect differing from that described upon EHD1 knockdown. Moreover, the subcellular localization of Rab11-FIP2 and endogenous Rab11 were altered upon EHD3 knockdown, with both proteins absent from the ERC and retained in the cell periphery. The results presented herein promote a coordinated role for EHD proteins and Rab11-FIP2 in mediating endocytic recycling and provide evidence for the function of EHD3 in early endosome to ERC transport.