Derlin-1 promotes the efficient degradation of the cystic fibrosis transmembrane conductance regulator (CFTR) and CFTR folding mutants
Derlin-1 promotes the efficient degradation of the cystic fibrosis transmembrane conductance regulator (CFTR) and CFTR folding mutants
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DOI：
10.1074/jbc.m607085200
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发表时间：
2006-12-01
影响因子：
4.8
通讯作者：
Frizzell, Raymond A.
中科院分区：
文献类型：
--
作者：
Sun, Fei;Zhang, Ruilin;Frizzell, Raymond A.
涉及Derlin-1和p97的复合物介导酵母中错误折叠蛋白质的逆易位和内质网（ER）相关降解，并被某些病毒用于促进宿主细胞蛋白质降解（Romisch，K.（2005）Annu.修订版细胞发育21，435-456; Lilley，B. N.，和Ploegh，H. L.（2004）Nature 429，834-840; Ye，Y.，柴田，Y.，Yun，C.，罗恩博士，Rapoport，T. A.（2004）Nature 429，841 847）。我们问这个途径的组件是否参与内质网相关的哺乳动物膜蛋白，囊性纤维化跨膜传导调节因子（CFTR），底物的泛素-蛋白酶体系统的降解。我们报告说，Derlin-1和p97形成复合物与CFTR在人气道上皮细胞。Derlin-1与非泛素化CFTR相互作用，而p97与泛素化CFTR相关。Derlin-1的外源表达导致其与CFTR共定位于ER中，其中其减少野生型（WT）CFTR表达并有效降解疾病相关的CFTR折叠突变体Delta F508和G85 E（> 90%）。与此一致，Derlin-1还减少了洗涤剂不溶性聚集体中出现的WT或Delta F508 CFTR的量。通过RNA干扰对内源性Derlin-1的类似于70%的敲低使WT和Delta F508 CFTR的稳态水平增加了10-15倍，反映了其在CFTR降解中的显著作用。Derlin-1介导的N-末端CFTR片段的降解对应于CFTR的第一个跨膜结构域，但CFTR片段，纳入额外的结构域降解效率较低。这些研究结果表明，Derlin-1识别错误折叠，nonubiquitylated CFTR启动其错位和降解过程中的CFTR生物合成的早期，也许是通过检测第一个跨膜结构域内的结构不稳定性。
A complex involving Derlin-1 and p97 mediates the retrotranslocation and endoplasmic reticulum (ER)-associated degradation of misfolded proteins in yeast and is used by certain viruses to promote host cell protein degradation (Romisch, K. (2005) Annu. Rev. Cell Dev. Biol. 21, 435-456; Lilley, B. N., and Ploegh, H. L. (2004) Nature 429, 834-840; Ye, Y., Shibata, Y., Yun, C., Ron, D., and Rapoport, T. A. (2004) Nature 429, 841 847). We asked whether the components of this pathway are involved in the endoplasmic reticulum-associated degradation of the mammalian integral membrane protein, the cystic fibrosis transmembrane conductance regulator (CFTR), a substrate for the ubiquitin-proteasome system. We report that Derlin-1 and p97 formed complexes with CFTR in human airway epithelial cells. Derlin-1 interacted with nonubiquitylated CFTR, whereas p97 associated with ubiquitylated CFTR. Exogenous expression of Derlin-1 led to its co-localization with CFTR in the ER where it reduced wild type (WT) CFTR expression and efficiently degraded the disease-associated CFTR folding mutants, Delta F508 and G85E (> 90%). Consistent with this, Derlin-1 also reduced the amount of WT or Delta F508 CFTR appearing in detergent-insoluble aggregates. An similar to 70% knockdown of endogenous Derlin-1 by RNA interference increased the steady-state levels of WT and Delta F508 CFTR by 10-15-fold, reflecting its significant role in CFTR degradation. Derlin-1 mediated the degradation of N-terminal CFTR fragments corresponding to the first transmembrane domain of CFTR, but CFTR fragments that incorporated additional domains were degraded less efficiently. These findings suggest that Derlin-1 recognizes misfolded, nonubiquitylated CFTR to initiate its dislocation and degradation early in the course of CFTR biogenesis, perhaps by detecting structural instability within the first transmembrane domain.