Role And Mechanisms Of SIRT3 On Hydrogen Sulfide Against Myocardial Hypertrophy

ObjectiveHydrogen sulfide?H₂S?is a gaseous signal molecule with anti-oxidative ability.Sirtuin 3?SIRT3?is closely associated with mitochondrial function and oxidative stress.The study was to investigate whether and how H₂S improved myocardial hypertrophy via an SIRT3-dependent manner.MethodsNeonatal cardiomyocytes from Sprague-Dawley?SD?rat were pre-treated with NaHS?50?M?for 4 h followed by angiotensin II?Ang II,100 nM?for 24 h,SIRT 3 promoter activity and expression were detected.After SIRT3 was silenced with siRNA technology,SIRT 3promoter activity and expression,cell surface,atrial natriuretic peptide?ANP?,brain natriuretic peptide?BNP?mRNA expression,mitochondrial oxygen consumption rate and membrane potential was measured after NaHS and Ang II was administrated.Male 129S1/SvImJ?WT?and SIRT3 KO mice were intraperitoneally injected with Na HS?50?mol/kg/d?followed by transverse aortic constriction?TAC?.Rats were injected with NaHS intraperitoneally for 2 weeks.The systolic blood pressure?SBP?,diastolic blood pressure?DBP?and mean arterial pressure?MAP?of mice was monitored every week.The left ventricular posterior wall?LVPW?,the thickness of interventricular septum?IVS?,ejection fraction?EF?and fraction shortening?FS?were measured by echocardiography after 2 weeks,heart weight?HW?,heart mass index?HMI?,left ventricular mass index?LVMI?and LVW/TL,ANP and BNP expression,the production level of H₂S in the plasma and myocardium were measured.Extraction of the tissue measuring the level of malondialdehyde?MDA?,the activity of total antioxidant capacity?T-AOC?and superoxide dismutase?SOD?.The ultrastructure of mitochondria was observed by transmission electron microscopy.The level of oxidative stress was measured by DHE staining.The expression of optic atrophy 1?OPA1?and dynamin-related protein 1?DRP1?were detected by immunofluorescence.ResultsExperiments in vitro showed that:1.Ang II induced cardiac hypertrophyand increased the expression of hypertrophy gene ANP,BNP mRNA.NaHS inhibitd the expression of cardiac hypertrophy gene and increased the activity of SIRT3 promoter and the expression of SIRT3 mRNA;However,the effect of NaHS was attenuated after silencing SIRT3.2.Ang II stimulation reduced mitochondrial respiration-related indicators,reduced the level of ROS and damaged mitochondrial membrane potential.NaHS reversed the above results,but afer SIRT3 silenced,NaHS effect was inhibited.It suggested that Na HS improved mitochondrial respiratory function and membrane potential in cardiomyocytes stimulated by Ang II in a SIRT3-dependent manner.Animal experiments showed that:1.WT mice and SIRT3 KO mice produced cardiac hypertrophy after TAC.NaHS reduced the blood pressure of WT and SIRT3 KO mice after TAC and improved H₂S levels in serum and myocardium with the similar degree,indicating that there was no difference on blood pressure and H₂S levels after NaHS administration in both WT and SIRT3 KO mice.2.M-type echocardiography showed that NaHS reduced the thickness of IVS and LVPW in WT mice after TAC,but could not reduce the cardiac configuration of SIRT3 KO mice after TAC.3.The HW,HMI,LVMI and LVW/TL of WT mice were increased after TAC.NaHS treatment decreased the above indexes in WT mice after TAC,but the above indexs in SIRT3 KO mice did not decrease.4.Real-time PCR analysis showed that Na HS decreased the expression of ANP and BNP mRNA in WT mice,however,this effect was not obvious in SIRT3 KO mice.5.NaHS significantly inhibited the DHE fluorescence and MDA levels in TAC,increased the activity of T-AOC and total SOD,but NaHS had no obvious inhibitory effect on SIRT3 KO mice.6.Transmission electron microscopy showed that mitochondrial cristae of cardiomyocyte reduced.Some mitochondrial membrane was fused with vacuolar formation and sarcomere disorder after TAC.NaHS increased mitochondrial cristae but attenuated vacuolar formation and sarcomere disorder,respecting improvement of mitochondrial ultrastructure,in myocardium of WT mice but not of SIRT3 KO mice.7.Immunofluorescence staining showed that NaHS enhanced the expression of OPA1 in WT mice rather than SIRT3KO mice after TAC,while decreasing the expression of DRP1 in WT mice rather than SIRT3 KO mice after TAC.Conclusions NaHS improved mitochondrial function and inhibited oxidative stress in myocardial hypertrophy via a SIRT3 dependent manner.