UBC9 Regulates the Stability of XBP1, a Key Transcription Factor Controlling the ER Stress Response

Cell Structure and Function

Yusaku Matsuo¹  Mai Taniguchi¹  Sadao Wakabayashi¹  Aya Uemura²  Hiderou Yoshida²  Masaya Oku² 

[1] Department of Molecular Biochemistry, Graduate School of Life Science, University of Hyogo;Department of Biophysics, Graduate School of Science, Kyoto University

关键词: ER stress response;    unfolded protein response;    chaperone;    XBP1;    UBC9;   

DOI  :  10.1247/csf.12026

学科分类：分子生物学，细胞生物学和基因

来源: Japan Society for Cell Biology

【 摘 要 】

References(46)Cited-By(5)XBP1 is a key transcription factor regulating the mammalian endoplasmic reticulum (ER) stress response, which is a cytoprotective mechanism for dealing with an accumulation of unfolded proteins in the ER (ER stress). The expression of XBP1 is regulated by two different mechanisms: mRNA splicing and protein stability. When ER stress occurs, unspliced XBP1 mRNA is converted to mature mRNA, from which an active transcription factor, pXBP1(S), is translated and activates the transcription of ER-related genes to dispose of unfolded proteins. In the absence of ER stress, pXBP1(U) is translated from unspliced XBP1 mRNA and enhances the degradation of pXBP1(S). Here, we analyzed the regulatory mechanism of pXBP1(S) stability, and found that a SUMO-conjugase, UBC9, specifically bound to the leucine zipper motif of pXBP1(S) and increased the stability of pXBP1(S). Suppression of UBC9 expression by RNA interference reduced both the expression of pXBP1(S) and ER stress-induced transcription by pXBP1(S). Interestingly, overexpression of a UBC9 mutant deficient in SUMO-conjugating activity was able to increase pXBP1(S) expression as well as wild-type UBC9, indicating that UBC9 stabilizes pXBP1(S) without conjugating SUMO moieties. From these observations, we concluded that UBC9 is a novel regulator of the mammalian ER stress response.

【 授权许可】

Unknown