Targeting Mitochondrial Deacetylase Sirt3 in Endothelial Dysfunction and Hypertension

Abstract

Hypertension is a multifactorial disorder involving perturbations of the vasculature, the kidney and the central nervous system. It represents a major risk factor for stroke, myocardial infarction, and heart failure; however, despite treatment with multiple drugs, one third of hypertensive patients remain hypertensive. We have recently shown that hypertension is associated with mitochondrial hyperacetylation due to reduced activity of the key mitochondrial deacetylase Sirt3 (Dikalova et al. Circ Res. 2017;121(5):564–574.). We hypothesized that targeting Sirt3 has therapeutic potential in endothelial dysfunction and hypertension. To test this hypothesis we have developed novel tamoxifen-inducible endothelium specific Sirt3 knockout (EcSirt3KO), inducible endothelial specific Sirt3 overexpressing (EcSirt3OX) mice and global Sirt3 overexpressing (Sirt3OX) on C57Bl/6J background, and examined the effect of Sirt3 expression on vascular dysfunction and hypertension. Blood pressure was measured by telemetry. Vascular superoxide was measured by HPLC analysis of O2• specific products of DHE and mitoSOX. Vascular NO was measured by EPR and NO spin trap Fe(DETC)2. Vascular reactivity was studied using isometric tension and vascular permeability was tested by Evans Blue assay. Angiotensin II-induced hypertension was markedly increased in EcSirt3KO compared with wild-type C57Bl/6J mice. Decrease of NO is a hallmark of endothelial dysfunction in hypertension due to vascular oxidative stress. Indeed, angiotensin II infusion in EcSirt3KO mice causes severe loss of endothelial nitric oxide (3-fold vs 2-fold in wild-type), overproduction of vascular superoxide, exacerbated endothelial dysfunction and increased vascular permeability. In contrast to EcSirt3KO, Sirt3 overexpression in Sirt3OX mice significantly attenuates hypertension by 25 mm Hg, prevents overproduction of vascular superoxide, protects endothelial dependent relaxation and vascular permeability. Interestingly, endothelial specific Sirt3 overexpression in EcSirt3OX mice mimics the protective effect of global Sirt3 overexpression by blocking vascular oxidative stress, protecting vascular relaxation and attenuating angiotensin II-induced hypertension. Our studies demonstrate that endothelial Sirt3 protects vascular functions and attenuates hypertension. These data support a therapeutic potential of targeting Sirt3 in vascular dysfunction and hypertension. Support or Funding Information This work was supported by funding from National Institute of Health (R01HL124116 and PO1HL129941), Vanderbilt University (VR7040 and UL1 RR024975). Dr. Dikalova was supported by American Heart Association (16GRNT31230017) and Dr. Itani was funded by the National Institute of Health (1F32HL124972). Vascular relaxation in wild-type and Sirt3OX mice before and after angiotensin II-infusion (0.7 mg/kg/day). Vascular reactivity was studied using isometric tension (B). Blood pressure in wild-type and Sirt3OX mice. (A) Systolic blood pressure was measured by telemetry before and after angiotensin II-infusion (0.7 mg/kg/day). Insert shows Western blot of Sirt3 and SOD2 in aorta mitochondria isolated from WT and Sirt3OX mice. Aaortic superoxide in wild-type and Sirt3OX mice before and after angiotensin II-infusion (0.7 mg/kg/day) was measured by DHE/HPLC assay (C). Results are mean ± SEM (n=5). *P<0.01 vs WT. **P<0.05 vs WT+AngII. Aortic endothelial nitric oxide in wild-type and Sirt3OX mice before and after angiotensin II-infusion (0.7 mg/kg/day) was measured by Electron Spin Resonance (D). Results are mean ± SEM (n=5). *P<0.01 vs WT. **P<0.05 vs WT+AngII. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.