Gao Zhanguo, Ye Jianping
Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
Biochem Biophys Res Commun. 2008 Nov 28;376(4):793-6. doi: 10.1016/j.bbrc.2008.09.079. Epub 2008 Sep 26.
c-JUN is a major component of heterodimer transcription factor AP-1 (Activator Protein-1) that activates gene transcription in cell proliferation, inflammation and stress responses. SIRT1 (Sirtuin 1) is a histone deacetylase that controls gene transcription through modification of chromatin structure. However, it is not clear if SIRT1 regulates c-JUN activity in the control of gene transcription. Here, we show that SIRT1 associated with c-JUN in co-immunoprecipitation of whole cell lysate, and inhibited the transcriptional activity of c-JUN in the mammalian two hybridization system. SIRT1 was found in the AP-1 response element in the matrix metalloproteinase-9 (MMP9) promoter DNA leading to inhibition of histone 3 acetylation as shown in a ChIP assay. The SIRT1 signal was reduced by the AP-1 activator PMA, and induced by the SIRT1 activator Resveratrol in the promoter DNA. SIRT1-mediaetd inhibition of AP-1 was demonstrated in the MMP9 gene expression at the gene promoter, mRNA and protein levels. In mouse embryonic fibroblast (MEF) with SIRT1 deficiency (SIRT1(-/-)), mRNA and protein of MMP9 were increased in the basal condition, and the inhibitory activity of Resveratrol was significantly attenuated. Glucose-induced MMP9 expression was also inhibited by SIRT1 in response to Resveratrol. These data consistently suggest that SIRT1 directly inhibits the transcriptional activity of AP-1 by targeting c-JUN.
c-JUN是异二聚体转录因子AP-1（激活蛋白-1）的主要组成部分，该因子在细胞增殖、炎症和应激反应中激活基因转录。SIRT1（沉默调节蛋白1）是一种组蛋白脱乙酰酶，通过改变染色质结构来控制基因转录。然而，尚不清楚SIRT1在基因转录调控中是否调节c-JUN的活性。在此，我们发现，在全细胞裂解物的共免疫沉淀中，SIRT1与c-JUN相关联，并在哺乳动物双杂交系统中抑制c-JUN的转录活性。如染色质免疫沉淀分析所示，在基质金属蛋白酶-9（MMP9）启动子DNA的AP-1反应元件中发现了SIRT1，其导致组蛋白3乙酰化受到抑制。在启动子DNA中，AP-1激活剂佛波酯（PMA）可降低SIRT1信号，而SIRT1激活剂白藜芦醇可诱导该信号。在基因启动子、mRNA和蛋白质水平上，均证实了SIRT1介导的对AP-1的抑制作用存在于MMP9基因表达中。在缺乏SIRT1（SIRT1(-/-)）的小鼠胚胎成纤维细胞（MEF）中，基础条件下MMP9的mRNA和蛋白质水平升高，白藜芦醇的抑制活性显著减弱。白藜芦醇处理后，SIRT1也可抑制葡萄糖诱导的MMP9表达。这些数据一致表明，SIRT1通过靶向c-JUN直接抑制AP-1的转录活性。
