Recycling of the Epidermal Growth Factor Receptor Is Mediated by a Novel Form of the Clathrin Adaptor Protein Eps15
Recycling of the Epidermal Growth Factor Receptor Is Mediated by a Novel Form of the Clathrin Adaptor Protein Eps15
复制标题
DOI：
10.1074/jbc.m111.247577
复制
发表时间：
2011-10-07
影响因子：
4.8
通讯作者：
McNiven, Mark A.
中科院分区：
文献类型：
--
作者：
Chi, Susan;Cao, Hong;McNiven, Mark A.
表皮生长因子受体（EGFR）在细胞表面的水平受到一个复杂的内吞机制的严格调节。在内化之后，EGFR被再循环回到细胞表面或转运到晚期内体/溶酶体进行降解。目前，调节这种分选途径的分子机制仅部分确定。Eps 15（EGFR途径底物15）是一种内吞衔接蛋白，已知其支持网格蛋白介导的EGFR在质膜上的内化。使用RT-PCR，我们已经确定了一种新的短形式的Eps 15（Eps 15 S）从大鼠肝脏，缺乏传统的Eps 15形式中存在的111个C-末端氨基酸。本研究的目的是确定新的Eps 15 S形式在EGFR运输中的功能作用。Eps 15 S突变体（Eps 15 S Delta EH 2/EH 3）的过表达并不阻断EGFR的内化，但减少了其向细胞表面的再循环。敲除所有Eps 15形式后，Eps 15 S的再表达显著降低了EGFR降解，同时促进再循环回到细胞表面。相反，Eps 15的再表达并不增强受体的再循环。此外，突变体Eps 15 S的过表达大大降低了细胞增殖，将EGFR回收与下游有丝分裂效应联系起来。最后，我们发现Eps 15 S定位于Rab 11阳性再循环内体，该内体在表达Eps 15 S突变体的细胞中被破坏，导致EGFR在早期内体中积累。这些发现表明，不同形式的Eps 15将EGFR引导至晚期内体/溶酶体以进行降解（Eps 15）或引导至再循环内体以转运回到细胞表面（Eps 15 S）。
Levels of the epidermal growth factor receptor (EGFR) at the cell surface are tightly regulated by a complex endocytic machinery. Following internalization, EGFR is either recycled back to the cell surface or transported to the late endosome/lysosome for degradation. Currently, the molecular machinery that regulates this sorting pathway is only partially defined. Eps15 (EGFR pathway substrate 15) is an endocytic adaptor protein that is well known to support clathrin-mediated internalization of EGFR at the plasma membrane. Using RT-PCR, we have identified a novel short form of Eps15 (Eps15S) from rat liver that lacks the 111 C-terminal amino acids present in the traditional Eps15 form. The goal of this study was to define the functional role of the novel Eps15S form in EGFR trafficking. Overexpression of a mutant form of Eps15S (Eps15S Delta EH2/EH3) did not block EGFR internalization but reduced its recycling to the cell surface. After knockdown of all Eps15 forms, re-expression of Eps15S significantly reduced EGFR degradation while promoting recycling back to the cell surface. In contrast, re-expression of Eps15 did not potentiate receptor recycling. Furthermore, overexpression of the mutant Eps15S substantially reduced cell proliferation, linking EGFR recycling to downstream mitogenic effects. Finally, we found that Eps15S is localized to the Rab11-positive recycling endosome that is disrupted in cells expressing the Eps15S mutant, leading to an accumulation of the EGFR in early endosomes. These findings suggest that distinct forms of Eps15 direct EGFR to either the late endosome/lysosome for degradation (Eps15) or to the recycling endosome for transit back to the cell surface (Eps15S).