A redox-resistant sirtuin-1 mutant protects against hepatic metabolic and oxidant stress.
Sirtuin-1 (SirT1), a member of the NAD(+)-dependent class III histone deacetylase family, is inactivated in vitro by oxidation of critical cysteine thiols. In a model of metabolic syndrome, SirT1 activation attenuated apoptosis of hepatocytes and improved liver function including lipid metabolism. We show in SirT1-overexpressing HepG2 cells that oxidants (nitrosocysteine and hydrogen peroxide) or metabolic stress (high palmitate and high glucose) inactivated SirT1 by reversible oxidative post-translational modifications (OPTMs) on three cysteines. Mutating these oxidation-sensitive cysteines to serine preserved SirT1 activity and abolished reversible OPTMs. Overexpressed mutant SirT1 maintained deacetylase activity and attenuated proapoptotic signaling, whereas overexpressed wild type SirT1 was less protective in metabolically or oxidant-stressed cells. To prove that OPTMs of SirT1 are glutathione (GSH) adducts, glutaredoxin-1 was overexpressed to remove this modification. Glutaredoxin-1 overexpression maintained endogenous SirT1 activity and prevented proapoptotic signaling in metabolically stressed HepG2 cells. The in vivo significance of oxidative inactivation of SirT1 was investigated in livers of high fat diet-fed C57/B6J mice. SirT1 deacetylase activity was decreased in the absence of changes in SirT1 expression and associated with a marked increase in OPTMs. These results indicate that glutathione adducts on specific SirT1 thiols may be responsible for dysfunctional SirT1 associated with liver disease in metabolic syndrome.
From the Vascular Biology Section and.
Di
D
Shao
Jessica L
JL
Fry
Jingyan
J
Han
Xiuyun
X
Hou
David R
DR
Pimentel
Reiko
R
Matsui
Richard A
RA
Cohen
Markus M
MM
Bachschmid
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D054477:Glutaredoxins / Q000235:genetics; D005978:Glutathione / Q000737:chemistry; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D008099:Liver / Q000378:metabolism*; D008107:Liver Diseases / Q000378:metabolism; D008297:Male; D024821:Metabolic Syndrome / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009154:Mutation; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D056564:Sirtuin 1 / Q000235:genetics*
D054477:Glutaredoxins; D016877:Oxidants; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; C447939:SIRT1 protein, human; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1; D005978:Glutathione; D010100:Oxygen
Glutathiolation; Glutathionylation; High Fat High Sucrose Diet; Metabolic Diseases; Oxidative Stress; Polyphenols; Reactive Oxygen and Nitrogen Species; Resveratrol