Research On The Mechanism Of Hypoxia Induces Mitochondrial Dysfunction Via TET2-mediated Demethylation To Participate In Cardiomyocyte Hypertrophy

Background: Cardiac hypertrophy is a common pathophysiological feature of many cardiovascular diseases,including: hypertension,coronary heart disease,cardiomyopathy and other pathological changes can be manifested as myocardial hypertrophy,and hypoxia is one of the common pathogenic factors of the above diseases.one.At present,the main causes of hypoxia are known to include ischemia and hypoxia,environment and aging,while the research on hypoxia and myocardial hypertrophy mainly focuses on the changes caused by ischemia,while ignoring the effects of environment,aging and other factors.According to research,environmental factors and aging can lead to abnormal epigenetic changes,and the latter is associated with many cardiovascular diseases,including cardiomyopathy.Cardiac hypertrophy is the main pathological change in heart failure,and changes in mitochondrial function and structure can be observed in hypertrophic cardiomyocytes.However,there is a lack of research on how hypoxia-induced DNA demethylation affects mitochondrial function and contributes to cardiac hypertrophy.Therefore,this study aimed to investigate the relationship between DNA demethylation and hypoxia-induced cardiac hypertrophy.Methods(1)AC16 passaged ventricular myocytes were treated with 21% O2 and 1% O2 for 6 h,respectively,to simulate normal oxygen concentration and hypoxia environment,and establish a hypoxia-induced myocardial hypertrophy model.(2)The expression levels of TET2 enzyme,ANP,β-MHC,Mfn2 and Drp1 protein in AC16 cells were examined by western blot.(3)The morphological changes of mitochondria were observed by transmission electron microscope(4)The pathological changes of AC16 ventricular myocytes were detected by WGA staining;(5)The level of intracellular mitochondrial membrane potential was detected by flow cytometry(6)Mfn2 was detected by pyrosequencing and Drp1 promoter region methylation levelsResults(1)In AC16 ventricular myocytes cultured under hypoxia,the cardiomyocytes were significantly hypertrophied,accompanied by increased expression of ANP and β-MHC.In hypertrophic cardiomyocytes,the expression of demethylation-related protein TET2 is increased,while the expression of proteins related to mitochondrial dynamics,Drp1 and Mfn2,is decreased,and the mitochondrial membrane potential is significantly reduced.It can be noted that the methylation levels of Mfn2 and Drp1 promoter regions reduce.(2)In AC16 ventricular myocytes cultured under hypoxia,different methods of inhibiting TET2 could reverse the decrease in the expression of Mfn2 and Drp1,and reverse the increase in the expression of ANP and β-MHC.At the same time,the methylation levels of Mfn2 and Drp1 promoter regions increased significantly.Conclusion: Our data suggest that there is a correlation between TET2 and markers of cardiac hypertrophic response.Inhibiting the expression of TET2 can help alleviate myocardial hypertrophy under hypoxic conditions by correcting mitochondrial dynamics disorders,and further improve mitochondrial fusion and fission affected by DNA demethylation in cardiomyocytes.Epigenetics and cardiac hypertrophy associated with hypoxia provide an experimental basis.