NO-induced downregulation of HSP10 and HSP60 expression in the postischemic brain
NO-induced downregulation of HSP10 and HSP60 expression in the postischemic brain
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DOI：
10.1002/jnr.21236
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发表时间：
2007-05-01
影响因子：
4.2
通讯作者：
Lee, Ja-Kyeong
中科院分区：
文献类型：
--
作者：
Kim, Seung-Woo;Lee, Ja-Kyeong
热休克蛋白60 （HSP60）和HSP10是线粒体伴侣蛋白，负责线粒体DNA编码的新输入蛋白和13多肽的折叠。HSP60和HSP10的表达同时受到调控，因为这些基因位于染色体上，由一个双向启动子分隔，该启动子包含热休克元件（HSE）、CHOP、STAT3和SP1结合位点。在本研究中，我们发现在大脑中动脉闭塞（MCAO）后，HSP60和HSP10的表达被显著诱导。有趣的是，HSP60和HSP10的表达被氨基胍（AG）进一步上调，氨基胍是一种诱导性一氧化氮合酶（iNOS）的抑制剂，已知可以减轻MCAO后动物模型的缺血性损伤。本研究结果表明，HSP10和HSP60在缺血后的大脑中被诱导，但在MCAO/再灌注后12小时产生的NO下调了HSP10和HSP60。体外实验证实了NO对HSP60和HSP10的下调作用，在C6星形胶质瘤细胞中，LPS和IFN γ (LPS/INF γ)处理后HSP10和SHP60的表达升高，另一种iNOS抑制剂NMMA进一步上调HSP10和SHP60的表达。报告基因分析结合缺失和突变研究表明，双向启动子中的STAT3结合位点负责LPS/INF γ诱导的上调和NO的下调。我们的研究结果表明，NO通过抑制STAT3与其识别位点的结合来抑制HSP60和HSP10在脑缺血后的诱导。(C) 2007 Wiley-Liss, Inc。
Heat shock protein 60 (HSP60) and HSP10 are mitochondrial chaperonin proteins and are responsible for the folding of newly imported proteins and 13 polypeptides encoded by mitochondrial DNA. The expressions of HSP60 and HSP10 are regulated simultaneously because these genes are localized head to head on chromosome, separated by a bidirectional promoter, which harbors heat shock element (HSE), CHOP, STAT3, and SP1 binding sites. In the present study, we show that the expressions of HSP60 and HSP10 in the brain after middle cerebral artery occlusion (MCAO) are induced significantly. Interestingly, the expressions of HSP60 and HSP10 were further upregulated by the administration of aminoguanidine (AG), an inhibitor of the inducible nitric oxide synthase (iNOS), which is known to reduce ischemic damage in an animal model after MCAO. The results obtained in the present study suggest that HSP10 and HSP60 are induced in the postischemic brain, yet are downregulated by NO generated from 12 hr after MCAO/ reperfusion. The downregulation of HSP60 and HSP10 by NO were confirmed in vitro, wherein HSP10 and SHP60 expressions were increased by treatment of LPS and IFN gamma (LPS/INF gamma) in C6 astroglioma cells and further upregulated by NMMA, another iNOS inhibitor. Reporter gene analysis combined with deletion and mutation studies showed that STAT3 binding site in the bidirectional promoter is responsible for LPS/INF gamma-induced upregulation and for downregulation by NO. Our results indicated that NO suppresses HSP60 and HSP10 inductions in the postischemic brain by suppressing STAT3 binding to its recognition site. (C) 2007 Wiley-Liss, Inc.