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Control of cell proliferation and differentiation by heme bindiny transcription factor Bachl

血红素结合转录因子 Bachl 控制细胞增殖和分化

基本信息

批准号：
17390080
负责人：
IGARASHI Kazuhiko
金额：
$ 9.28万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

The transcription repressor Bach1 is a sensor and an effecter of heme that regulates the expression of heme oxygenase-1 and globin genes. Heme binds to Bachl, inhibiting its DNA binding activity and inducing its nuclear export. We found that hemin further induced the degradation of endogenous Bachl in NIH3T3 cells, murine embryonic fibroblasts, and murine erythroleukemia cells. In contrast, succinylacetone, an inhibitor of heme synthesis, caused accumulation of Bachl in murine embryonic fibroblasts, indicating that physiological levels of heme regulated the Bachl turnover. Poly-ubiquitination and rapid degradation of overexpressed Bachl were induced by hemin treatment. HOIL-1, an ubiquitin-protein ligase which recognizes heme-bound, oxidized iron regulatory protein 2, was found to bind with Bachl when both were overexpressed in NIH3T3 cells. HOIL-1 stimulated the poly-ubiquitination of Bachl in a purified in vitro ubiquitination system depending on the intact heme binding motifs of Bachl. Expression of dominant negative HOIL-1 in murine erythroleukemia cells resulted in higher stability of endogenous Bachl, raising the possibility that the heme-regulated degradation involved HOIL-1 in murine erythroleukemia. cells. These results suggest that heme within a cell regulates the poly-ubiquitination and degradation of Bachl.In addition, we found in this study that Bachl inhibits oxidative stress-induced cellular senescence. Bachl-deficient murine embryonic fibroblasts (MEFs) showed profound cellular senescence in response to oxygen in vitro as compared to wild-type control MEFs. Expression profiling of Bachl-deficient MEFs suggested that overexpression of several genes might be responsible for the oxygen-induced cellular senescence.

转录抑制因子Bach1是血红素的感受器和效应器，调节血红素加氧酶-1和珠蛋白基因的表达。血红素与Bachl结合，抑制其DNA结合活性，并诱导其核输出。我们发现氯化血红素在NIH3T3细胞、小鼠胚胎成纤维细胞和小鼠红白血病细胞中进一步诱导内源性Bachl的降解。相比之下，血红素合成的抑制剂琥珀酰丙酮导致小鼠胚胎成纤维细胞中Bachl的积累，表明生理水平的血红素调节Bachl的周转。氯化高铁血红素可诱导Bachl的多泛素化和快速降解。HOIL-1是一种识别血红素结合的氧化铁调节蛋白2的泛素蛋白连接酶，当两者在NIH3T3细胞中过表达时，HOIL-1被发现与Bachl结合。HOIL-1在体外纯化的泛素化系统中刺激Bachl的多泛素化，依赖于Bachl完整的血红素结合基序。在小鼠红白血病细胞中表达显性负性HOIL-1导致内源性Bachl具有更高的稳定性，增加了血红素调节的降解涉及HOIL-1在小鼠红白血病中的可能性。细胞。这些结果表明，细胞内的血红素调节了Bachl的多泛素化和降解。此外，我们在本研究中发现Bachl抑制了氧化应激诱导的细胞衰老。与野生型对照小鼠胚胎成纤维细胞相比，Bachl基因缺陷的小鼠胚胎成纤维细胞(MEF)在体外对氧气的反应显示出严重的细胞衰老。Bachl缺陷型MEF的表达谱表明，几个基因的过度表达可能与氧诱导的细胞衰老有关。