The Deubiquitinating Enzyme USP8 Promotes Trafficking and Degradation of the Chemokine Receptor 4 at the Sorting Endosome
The Deubiquitinating Enzyme USP8 Promotes Trafficking and Degradation of the Chemokine Receptor 4 at the Sorting Endosome
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DOI：
10.1074/jbc.m110.129411
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发表时间：
2010-11-26
影响因子：
4.8
通讯作者：
Nash, Piers D.
中科院分区：
文献类型：
--
作者：
Berlin, Ilana;Higginbotham, Katherine M.;Nash, Piers D.
可逆的泛素化由泛素连接酶和去泛素化酶的相互作用所协调，介导细胞表面受体的内吞运输以进行溶酶体降解。泛素特异性蛋白酶8（USP 8）先前已经通过其去泛素化而涉及几种受体的内吞作用。本研究探讨了USP 8通过调节趋化因子受体4（CXCR 4）在货物运输中的间接作用。与USP 8缺失对增强型绿色荧光蛋白的影响相反，我们发现USP 8缺失稳定了细胞表面上的CXCR 4，并减弱了受体降解，而不影响其泛素化状态。在配体的存在下，减少CXCR 4周转伴随着受体在扩大的早期内体上的积累，并导致磷酸化ERK信号传导的增强。由USP 8失活引起的CXCR 4运输的扰动发生在ESCRT-0检查点，特异性靶向ESCRT-0复合物的USP 8的催化突变损害了分选内体的空间和时间组织。USP 8在功能上对抗泛素连接酶AIP 4对ESCRT-0的泛素化，从而促进CXCR 4的运输。总的来说，我们的研究结果表明，在CXCR 4的早期分选阶段，USP 8、AIP 4和ESCRT-0机制之间存在功能性合作，并强调了USP 8在早期至晚期内体转变中塑造贩运事件的多功能性。
Reversible ubiquitination orchestrated by the opposition of ubiquitin ligases and deubiquitinating enzymes mediates endocytic trafficking of cell surface receptors for lysosomal degradation. Ubiquitin-specific protease 8 (USP8) has previously been implicated in endocytosis of several receptors by virtue of their deubiquitination. The present study explores an indirect role for USP8 in cargo trafficking through its regulation of the chemokine receptor 4 (CXCR4). Contrary to the effects of USP8 loss on enhanced green fluorescent protein, we find that USP8 depletion stabilizes CXCR4 on the cell surface and attenuates receptor degradation without affecting its ubiquitination status. In the presence of ligand, diminished CXCR4 turnover is accompanied by receptor accumulation on enlarged early endosomes and leads to enhancement of phospho-ERK signaling. Perturbation in CXCR4 trafficking, resulting from USP8 inactivation, occurs at the ESCRT-0 checkpoint, and catalytic mutation of USP8 specifically targeted to the ESCRT-0 complex impairs the spatial and temporal organization of the sorting endosome. USP8 functionally opposes the ubiquitin ligase AIP4 with respect to ESCRT-0 ubiquitination, thereby promoting trafficking of CXCR4. Collectively, our findings demonstrate a functional cooperation between USP8, AIP4, and the ESCRT-0 machinery at the early sorting phase of CXCR4 and underscore the versatility of USP8 in shaping trafficking events at the early-to-late endosome transition.