GRIF1 binds Hrs and is a new regulator of endosomal trafficking
GRIF1 binds Hrs and is a new regulator of endosomal trafficking
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DOI：
10.1242/jcs.03249
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发表时间：
2006-11-15
影响因子：
4
通讯作者：
Li, Lian
中科院分区：
文献类型：
--
作者：
Kirk, Elizabeth;Chin, Lih-Shen;Li, Lian
内化的细胞表面受体向溶酶体途径的内体分选在细胞信号传导和功能的控制中起着至关重要的作用。在此我们报道了γ-氨基丁酸A（GABA(A)）受体相互作用因子 - 1（GRIF1）的鉴定，它是一种最近发现的功能未知的蛋白质，是内体到溶酶体运输的一种新的调节因子。酵母双杂交筛选和免疫共沉淀分析表明，GRIF1与肝细胞生长因子调节的酪氨酸激酶底物（Hrs）相互作用，Hrs是内体分选机制的一个重要组成部分。我们绘制了介导它们相互作用的GRIF1和Hrs的结合结构域，并显示了GRIF1与Hrs在早期内体上的共定位。与Hrs一样，GRIF1的过表达和小干扰RNA（siRNA）介导的缺失都抑制内化的表皮生长因子受体的降解，并阻断受体从早期内体向溶酶体途径的运输。我们的结果首次表明GRIF1在调节内体运输中具有功能性作用。有趣的是，全长GRIF1的过表达，而不是与Hrs或驱动蛋白相互作用的GRIF1缺失突变体，会导致早期内体在核周聚集。我们的研究结果表明，GRIF1还可能通过作为一种衔接蛋白，将含有Hrs的内体与驱动蛋白连接起来，参与基于微管的早期内体运输。
Endosomal sorting of internalized cell surface receptors to the lysosomal pathway plays a crucial role in the control of cell signaling and function. Here we report the identification of GABA(A) receptor interacting factor-1 (GRIF1),a recently discovered protein of unknown function, as a new regulator of endosome-to-lysosome trafficking. Yeast two-hybrid screen and co-immunoprecipitation analysis reveal that GRIF1 interacts with hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs), an essential component of the endosomal sorting machinery. We have mapped the binding domains of GRIF1 and Hrs that mediate their association and shown the colocalization of GRIF1 with Hrs on early endosomes. Like Hrs, both overexpression and siRNA-mediated depletion of GRIF1 inhibit the degradation of internalized epidermal growth factor receptors and block the trafficking of the receptors from early endosomes to the lysosomal pathway. Our results indicate, for the first time, a functional role for GRIF1 in the regulation of endosomal trafficking. Interestingly, overexpression of full-length GRIF1, but not the Hrs- or kinesin-interacting GRIF1 deletion mutants, causes a perinuclear clustering of early endosomes. Our findings suggest that GRIF1 may also participate in microtubule-based transport of early endosomes by acting as an adaptor linking Hrs- containing endosomes to kinesin.