title: Sirt1 modulates premature senescence-like phenotype in human endothelial cells.
abstract: Yeast Sir2 plays critical roles in gene silencing, stress resistance and longevity. Mammalian Sirt1 NAD(+)-dependent protein deacetylase, the closest homolog of Sir2, regulates cell cycle, cellular senescence, apoptosis and metabolism, by functional interactions with a number of biological molecules such as p53. To investigate a role of Sirt1 in endothelial dysfunction and premature senescence, we examined the effects of Sirt1 inhibition in human umbilical vein endothelial cells (HUVEC). Sirt1 inhibition by sirtinol, which is a 2-hydroxy-1-napthaldehyde derivative, or siRNA for Sirt1-induced premature senescence-like phenotype, as judged by increased senescence-associated beta-galactosidase (SA-beta-gal) activity, sustained growth arrest and enlarged and flattened cell morphology at 10 days after the treatment. Sixty-four percent of sirtinol (60 mumol/L)-treated HUVEC was SA-beta-gal-positive, whereas only 17% of vehicle-treated cells were positive. Sirt1 inhibition by sirtinol or Sirt1 siRNA increased PAI-1 expression and decreased both protein expression and activity of eNOS. Treatment with sirtinol or Sirt1 siRNA increased acetylation of p53, while p53 expression was unaltered. Impaired epidermal growth factor-induced activation of mitogen-activated protein kinases was associated with Sirt1 inhibition-induced senescence-like growth arrest. Conversely, overexpression of Sirt1 prevented hydrogen peroxide-induced SA-beta-gal activity, morphological changes and deranged expression of PAI-1 and eNOS. These results showed that Sirt1 inhibition increased p53 acetylation and induced premature senescence-like phenotype in parallel with increased PAI-1 and decreased eNOS expression. Our data suggest that Sirt1 may exert protective effects against endothelial dysfunction by preventing stress-induced premature senescence and deranged expression of PAI-1 and eNOS.
authors.affiliation: Department of Geriatric Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Ota
authors.forename: Masahiro
authors.initials: M
authors.lastname: Akishita
authors.forename: Masato
authors.initials: M
authors.lastname: Eto
authors.forename: Katsuya
authors.initials: K
authors.lastname: Iijima
authors.forename: Masao
authors.initials: M
authors.lastname: Kaneki
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Ouchi
mesh_terms: D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000235:genetics*; D004730:Endothelium, Vascular / Q000201:enzymology / Q000502:physiology*; D006801:Humans; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010641:Phenotype; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D056564:Sirtuin 1; D037761:Sirtuins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D014471:Umbilical Veins; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D019001:Nitric Oxide Synthase; D001616:beta-Galactosidase; C447939:SIRT1 protein, human; D056564:Sirtuin 1; D037761:Sirtuins