The Keap1-BTB protein is an adaptor that bridges Nrf2 to a Cul3-based E3 ligase: Oxidative stress sensing by a Cul3-Keap1 ligase
The Keap1-BTB protein is an adaptor that bridges Nrf2 to a Cul3-based E3 ligase: Oxidative stress sensing by a Cul3-Keap1 ligase
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DOI：
10.1128/mcb.24.19.8477-8486.2004
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发表时间：
2004-10-01
影响因子：
5.3
通讯作者：
Diehl, JA
中科院分区：
文献类型：
--
作者：
Cullinan, SB;Gordan, JD;Diehl, JA
Nrf2转录因子在引发氧化损伤的细胞损伤后促进细胞存活。Nrf2的活性受到BTB/POZ结构域蛋白Keap1的抑制。据推测，Keap1完全通过其抑制Nrf2核输入的能力来调节Nrf2的活性。近期的研究表明，对Nrf2的抑制可能还取决于泛素介导的蛋白水解作用。为了阐明依赖于Keap1的隔离作用与Nrf2蛋白水解作用的贡献，我们确定了调节Nrf2泛素化的E3连接酶。我们证明Keap1不仅仅是一种胞质锚定蛋白；相反，Keap1是一种将Nrf2连接到Cul3的衔接蛋白。我们证明Cul3 - Keap1复合物在体外和体内都调节Nrf2的多聚泛素化。抑制Keap1或Cul3都会增加Nrf2在核内的积累，导致Nrf2依赖的基因表达的杂乱激活。我们的数据表明，Keap1通过其将Nrf2靶向一种基于细胞质Cul3的E3连接酶的能力来抑制Nrf2的活性，并提出了一种模型，即Keap1协调调节Nrf2的积累以及对靶基因的可及性。
The Nrf2 transcription factor promotes survival following cellular insults that trigger oxidative damage. Nrf2 activity is opposed by the BTB/POZ domain protein Keap1. Keap1 is proposed to regulate Nrf2 activity strictly through its capacity to inhibit Nrf2 nuclear import. Recent work suggests that inhibition of Nrf2 may also depend upon ubiquitin-mediated proteolysis. To address the contribution of Keap1-dependent sequestration versus Nrf2 proteolysis, we identified the E3 ligase that regulates Nrf2 ubiquitination. We demonstrate that Keap1 is not solely a cytosolic anchor; rather, Keap1 is an adaptor that bridges Nrf2 to Cul3. We demonstrate that Cul3-Keap1 complexes regulate Nrf2 polyubiquitination both in vitro and in vivo. Inhibition of either Keap1 or Cul3 increases Nrf2 nuclear accumulation, leading to promiscuous activation of Nrf2-dependent gene expression. Our data demonstrate that Keap1 restrains Nrf2 activity via its capacity to target Nrf2 to a cytoplasmic Cul3-based E3 ligase and suggest a model in which Keap1 coordinately regulates both Nrf2 accumulation and access to target genes.