title: Involvement of the p65/RelA subunit of NF-kappaB in TNF-alpha-induced SIRT1 expression in vascular smooth muscle cells.
abstract: The proinflammatory cytokine TNF-alpha plays an important role in stimulating inflammatory responses of vascular smooth muscle cells (VSMCs). The anti-inflammatory function of Sirtuin 1 (SIRT1), a NAD-dependent class III histone/protein deacetylase, has been well documented, but how SIRT1 is regulated under inflammatory conditions is largely unknown. In the present research, we showed that levels of SIRT1 mRNA and protein expression increased in TNF-alpha-treated VSMCs. Overexpression of the p65/RelA subunit of NF-kappaB, a TNF-alpha-activated inflammatory transcription factor, in A7r5 cells, upregulated SIRT1 mRNA and protein expression as well as SIRT1 promoter activity, while knockdown of endogenous p65/RelA expression by RNAi not only led to a decrease in SIRT1's basal protein expression and promoter activity, but almost abolished the TNF-alpha-induced elevation of SIRT1 protein expression and SIRT1 promoter activity. Furthermore, using promoter deletion analysis and chromatin immunoprecipitation assays, we found that p65/RelA bound to the SIRT1 promoter at a consensus NF-kappaB binding site. Our study indicates that p65/RelA mediates the TNF-alpha-induced elevated expression of SIRT1 in VSMCs, shedding new light on the regulation of SIRT1 under inflammatory conditions.
authors.affiliation: National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 5 Dong Dan San Tiao, Beijing 100005, China.
authors.forename: Hui-Na
authors.initials: HN
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Peng
authors.initials: P
authors.lastname: Gao
authors.forename: Hou-Zao
authors.initials: HZ
authors.lastname: Chen
authors.forename: Ran
authors.initials: R
authors.lastname: Zhang
authors.forename: Yu-Sheng
authors.initials: YS
authors.lastname: Wei
authors.forename: De-Pei
authors.initials: DP
authors.lastname: Liu
authors.forename: Chih-Chuan
authors.initials: CC
authors.lastname: Liang
mesh_terms: D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D056564:Sirtuin 1 / Q000096:biosynthesis* / Q000235:genetics; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; C447939:SIRT1 protein, human; D056564:Sirtuin 1