title: Redox factor-1 activates endothelial SIRTUIN1 through reduction of conserved cysteine sulfhydryls in its deacetylase domain.
abstract: Apurinic/Apyrmidinic Endonuclease 1/Redox Factor-1 (APE1/Ref-1) is a reductant which is important for vascular homeostasis. SIRTUIN1 (SIRT1) is a lysine deacetylase that also promotes endothelium-dependent vasorelaxation. We asked if APE1/Ref-1 governs the redox state and activity of SIRT1, and whether SIRT1 mediates the effect of APE1/Ref-1 on endothelium-dependent vascular function. APE1/Ref-1 maintains sulfhydryl (thiol) groups of cysteine residues in SIRT1 in the reduced form and promotes endothelial SIRT1 activity. APE1/Ref-1 stimulates SIRT1 activity by targeting highly conserved vicinal thiols 371 and 374 which form a zinc tetra-thiolate motif in the deacetylase domain of SIRT1. Cysteine residues in the N-terminal redox domain of APE1/Ref-1 are essential for reducing SIRT1 and stimulating its activity. APE1/Ref-1 protects endothelial SIRT1 from hydrogen peroxide-induced oxidation of sulfhydryls and from inactivation. APE1/Ref-1 also promotes lysine deacetylation of the SIRT1 target endothelial nitric oxide synthase (eNOS). SIRT1 mutated at cysteines 371 and 374, which renders it non-reducible by APE1/Ref-1, prevents lysine deacetylation of eNOS by APE1/Ref-1. SIRT1 free thiol (reduced sulfhydryl) content and deacetylase activity are diminished in all examined tissues of APE1/Ref-1(+/-) mice, including the vasculature. Overexpression of SIRT1 in aortas of APE1/Ref-1(+/-) mice restores endothelium-dependent vasorelaxation and bioavailable nitric oxide (NO) to levels similar to those observed in wild-type mice. Thus, APE1/Ref-1, by maintaining functionally important cysteine sulfhydryls in SIRT1 in the reduced form, promotes endothelial SIRT1 activity. This reductive activation of endothelial SIRT1 by APE1/Ref-1 mediates the effect of APE1/Ref-1 on eNOS acetylation, promoting endothelium-derived NO and endothelium-dependent vasorelaxation.
authors.affiliation: Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Saet-Byel
authors.initials: SB
authors.lastname: Jung
authors.forename: Cuk-Seong
authors.initials: CS
authors.lastname: Kim
authors.forename: Young-Rae
authors.initials: YR
authors.lastname: Kim
authors.forename: Asma
authors.initials: A
authors.lastname: Naqvi
authors.forename: Tohru
authors.initials: T
authors.lastname: Yamamori
authors.forename: Santosh
authors.initials: S
authors.lastname: Kumar
authors.forename: Ajay
authors.initials: A
authors.lastname: Kumar
authors.forename: Kaikobad
authors.initials: K
authors.lastname: Irani
mesh_terms: D000107:Acetylation; D000818:Animals; D001011:Aorta / Q000201:enzymology; D003545:Cysteine / Q000378:metabolism*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000235:genetics / Q000378:metabolism*; D015194:Diffusion Chambers, Culture; D004730:Endothelium, Vascular / Q000201:enzymology*; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009569:Nitric Oxide / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D015398:Signal Transduction; D056564:Sirtuin 1 / Q000235:genetics / Q000378:metabolism*; D046509:Tissue Culture Techniques; D014664:Vasodilation / Q000235:genetics
chemical_list: D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1; C486216:Apex1 protein, mouse; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D003545:Cysteine