title: Reactive oxygen species derived from NADPH oxidase 1 and mitochondria mediate angiotensin II-induced smooth muscle cell senescence.
abstract: Cellular senescence has emerged as an important player in both physiology and pathology. Excessive reactive oxygen species (ROS) is known to mediate cellular senescence. NADPH oxidases are major sources for ROS production in the vascular wall; the roles of different NADPH oxidase isoforms in cellular senescence remain unclear, however. We investigated the roles of two NADPH oxidase isoforms in mitochondrial dysfunction during angiotensin II (Ang II)-induced cellular senescence of human aortic vascular smooth muscle cells (VSMCs). Ang II (10(-7)M) stimulated ROS generation, exhibiting early increases between 30 and 60min and sustained increases between 24h and 72h, and induced VSMCs senescence after 48h or 72h treatment as assessed with senescence-associated β-galactosidase activity and the expression of two cell cycle inhibitors, p21 and p16. ROS scavengers and membrane-permeable catalase (catalase-PEG) reduced Ang II-stimulated cellular senescence. Furthermore, small interfering RNA (siRNA) of NADPH oxidase catalytic subunit Nox1, but not that of another isoform Nox4, inhibited Ang II-induced cellular senescence. Nox1 siRNA inhibited both early and sustained ROS increases induced by Ang II. In addition, a mitochondrial-specific antioxidant, mitoQ10, effectively inhibited Ang II-induced ROS increases and cellular senescence. Ang II decreased ATP synthesis and induced mitochondrial membrane depolarization, which were attenuated by pre-treating cells with Nox1 siRNA, mitoQ10 or catalase-PEG. The effect of Ang II on the mitochondrial regulator peroxisome-proliferator-activated receptor gamma coactivator-1α (PGC-1α) and its downstream genes was examined. Ang II stimulated S570 phosphorylation of PGC-1α with concomitant decreases in catalase and uncoupling protein-2 (UCP-2) levels between 12h and 72h, which were inhibited by Nox1 siRNA. Knockdown of both catalase and UCP-2 mimicked Ang II-induced VSMC senescence. These results suggested that Ang II-stimulated Nox1 activation mediates mitochondrial dysfunction, probably by decreasing PGC-1α activity and increasing mitochondrial oxidative stress, and leads to cellular senescence of VSMCs.
authors.affiliation: Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: I-Ching
authors.initials: IC
authors.lastname: Tsai
authors.affiliation: Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Zih-Cian
authors.initials: ZC
authors.lastname: Pan
authors.affiliation: Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Hui-Pin
authors.initials: HP
authors.lastname: Cheng
authors.affiliation: Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Chen-Hsiu
authors.initials: CH
authors.lastname: Liu
authors.affiliation: Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
authors.forename: Bor-Tyng
authors.initials: BT
authors.lastname: Lin
authors.affiliation: Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Tainan 70101, Taiwan; Cardiovascular Research Center, National Cheng Kung University, Tainan 70101, Taiwan. Electronic address: mjiang@mail.ncku.edu.tw.
authors.forename: Meei Jyh
authors.initials: MJ
authors.lastname: Jiang
mesh_terms: D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D002478:Cells, Cultured; D016922:Cellular Senescence; D055785:Gene Knockdown Techniques; D006801:Humans; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha / Q000378:metabolism; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species / Q000378:metabolism*; D000071246:Uncoupling Protein 2 / Q000378:metabolism
chemical_list: D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D000071246:Uncoupling Protein 2; D000804:Angiotensin II; D002374:Catalase; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases; C402799:NOX1 protein, human
keywords: Angiotensin II; Cellular senescence; Mitochondria; NADPH oxidase 1; Reactive oxygen species; Vascular smooth muscle cells