The Nrf1 CNC-bZIP protein is regulated by the proteasome and activated by hypoxia.
The Nrf1 CNC-bZIP protein is regulated by the proteasome and activated by hypoxia.
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DOI：
10.1371/journal.pone.0029167
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Willmore WG
中科院分区：
文献类型：
--
作者：
Chepelev NL;Bennitz JD;Huang T;McBride S;Willmore WG
Nrf1（核因子-红细胞2 p45亚基相关因子1）是一种介导细胞对外源和促氧化应激反应的转录因子。Nrf1通过位于启动子区域的亲电反应元件（EpREs）调控许多应激相关基因的转录。尽管Nrf1对人类健康具有潜在的重要性，但其控制机制尚未得到充分研究。我们发现蛋白酶体抑制剂MG-132和clasto-lactacystin-β-内酯稳定了全长Nrf1在COS7和WFF2002细胞中的表达。同时，蛋白酶体抑制降低了一个较小的n端Nrf1片段的表达，其分子量约为23 kDa。EpRE-luciferase报告基因检测显示，蛋白酶体抑制显著抑制Nrf1的转激活活性。这些结果支持了先前的假设，即26s蛋白酶体通过去除将Nrf1固定在内质网上的抑制n端结构域，将Nrf1加工成活性形式。免疫沉淀表明Nrf1泛素化，蛋白酶体抑制增加了Nrf1泛素化的程度。此外，Nrf1蛋白在COS7细胞中的半衰期约为5小时。相比之下，缺氧（1% O2）显著增加了外源性Nrf1蛋白的荧光素酶报告活性，同时降低了p65的蛋白表达，p65是Nrf1的一种较短的形式，被认为是epre控制基因表达的抑制因子。最后，蛋白磷酸酶抑制剂冈田酸激活Nrf1报告因子活性，而后者被PKC抑制剂staurosporine抑制。总的来说，我们的数据表明Nrf1受几种翻译后机制的控制，包括泛素化、蛋白水解加工和蛋白酶体介导的降解，以及它的磷酸化状态。
Nrf1 (nuclear factor-erythroid 2 p45 subunit-related factor 1) is a transcription factor mediating cellular responses to xenobiotic and pro-oxidant stress. Nrf1 regulates the transcription of many stress-related genes through the electrophile response elements (EpREs) located in their promoter regions. Despite its potential importance in human health, the mechanisms controlling Nrf1 have not been addressed fully. We found that proteasomal inhibitors MG-132 and clasto-lactacystin-β-lactone stabilized the protein expression of full-length Nrf1 in both COS7 and WFF2002 cells. Concomitantly, proteasomal inhibition decreased the expression of a smaller, N-terminal Nrf1 fragment, with an approximate molecular weight of 23 kDa. The EpRE-luciferase reporter assays revealed that proteasomal inhibition markedly inhibited the Nrf1 transactivational activity. These results support earlier hypotheses that the 26 S proteasome processes Nrf1 into its active form by removing its inhibitory N-terminal domain anchoring Nrf1 to the endoplasmic reticulum. Immunoprecipitation demonstrated that Nrf1 is ubiquitinated and that proteasomal inhibition increased the degree of Nrf1 ubiquitination. Furthermore, Nrf1 protein had a half-life of approximately 5 hours in COS7 cells. In contrast, hypoxia (1% O2) significantly increased the luciferase reporter activity of exogenous Nrf1 protein, while decreasing the protein expression of p65, a shorter form of Nrf1, known to act as a repressor of EpRE-controlled gene expression. Finally, the protein phosphatase inhibitor okadaic acid activated Nrf1 reporter activity, while the latter was repressed by the PKC inhibitor staurosporine. Collectively, our data suggests that Nrf1 is controlled by several post-translational mechanisms, including ubiquitination, proteolytic processing and proteasomal-mediated degradation as well as by its phosphorylation status.
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影响因子：
10.5
作者：
Itoh, K;Wakabayashi, N;Yamamoto, M
通讯作者：
Yamamoto, M
影响因子：
56.9
作者：
ROGERS, S;WELLS, R;RECHSTEINER, M
通讯作者：
RECHSTEINER, M
影响因子：
5.8
作者：
Larkin, M. A.;Blackshields, G.;Higgins, D. G.
通讯作者：
Higgins, D. G.
影响因子：
3.8
作者：
Li, J;Johnson, D;Johnson, J
通讯作者：
Johnson, J
DOI：
10.1073/pnas.1019209108
发表时间：
2011-05-17
影响因子：
11.1
作者：
Lee, Candy S.;Lee, Chiashan;Chan, Jefferson Y.
通讯作者：
Chan, Jefferson Y.