文章基本信息

标题：Small ubiquitin-related modifier-1 modification mediates resolution of CREB-dependent responses to hypoxia
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作者：Katrina M. Comerford ; Martin O. Leonard ; Jorn Karhausen 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：3
页码：986-991
DOI：10.1073/pnas.0337412100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Phosphorylation-dependent ubiquitination combined with proteasomal degradation of transcriptional regulators is a recently appreciated mechanism for control of a number of inflammatory genes. Far less is known about the counterregulatory mechanisms that repress transcriptional activity in these pathways during resolution. Here, we investigated the transient nature of hypoxia-induced tumor necrosis factor (TNF) in T84 cells, a process we have previously shown to involve phosphorylation-dependent degradation of the cAMP-response element-binding protein (CREB). Initial studies indicate hypoxia-induced TNF to be a transient event, the resolution of which is associated with the appearance of a higher molecular weight modified form of CREB. Gene array analysis of mRNA derived from hypoxic cells identified a time-dependent induction of small ubiquitin-related modifier (SUMO)-1 mRNA. In prolonged hypoxia, CREB is posttranslationally modified by SUMO-1. Furthermore, SUMO-1 overexpression stabilizes CREB in hypoxia and enhances CREB-dependent reporter gene activity. Site-directed mutagenesis of lysine residues K285 and K304 identifies them as SUMO acceptors in vivo and in vitro. Mutation of K304 also results in loss of CREB nuclear localization, implying a role for SUMO-1 modification at this site in the subcellular localization of CREB. Thus, in prolonged hypoxia, CREB is modified by association with SUMO-1. Furthermore, we hypothesize that such an event stabilizes and promotes nuclear localization of CREB and thus complements an endogenous resolution phase for hypoxia-induced inflammatory processes.