The Effect Of Egcg,a Hdac Inhibitor,on Expression Of Ctni In Rcm Mouse

Our previous studies on cTnIR193H-restricted cardiomyopathy model mice found that the imbalance between cTnI and mutant cTnI,i.e,decreased normal cTnI and accumulation of abnormal cTn I is one of the pathogenesis of restrictive cardiomyopathy.Previous study has demonstrated that EGCG can reduce the sensitivity of cardiomyocytes to calcium and effectively improve diastolic dysfunction in mice.Our previous study revealed that older mice have physiological diastolic dysfunction.When EGCG is given,cTnI expression is significantly improved and diastolic dysfunction related with age is alleviated,while the mechanism underlying remains unresolved.So the question is whether EGCG can control the expression of normal cTnI by regulating the normal cTnI histone acetylation level of the TnIR193H-restricted cardiomyopathy model mice,so as to improve the mice’s diastolic dysfunction.EGCG have many active,which can reduce the activity of histone deacetylase and regulate gene expression.In this study,we tried to treat cTnI R193H-restricted cardiomyopathy model mice with EGCG to increase the expression of normal cTn I,thereby improving the diastolic dysfunction in mice.ObjectiveEGCG is a broad-spectrum of histone deacetylase inhibitors that can also increase cTnI expression in myocardium of older mice,which was confirmed by our earlier study.The main clinical manifestation of cTnIR193H-restricted cardiomyopathy model mice was diastolic dysfunction that could be improved by EGCG administration,which was also confirmed by our earlier study.In this study,cTn IR193H-restricted cardiomyopathy model mice were treated with EGCG for as long as 3 months to investigate whether EGCG could increase normal cTnI expression,and,if so,the regulatory mechanism of EGCG on normal cTnI genomic histone acetylation in model mice would be discussed.Methods30 C57 BL / 6 mice and 30 cTn I R193 H male mice(8 weeks old,healthy,SPF)were randomly divided into EGCG + mice group,DMSO + mice group and untreated mice group.EGCG given 50 mg /(kg·d).DMSO were given intraperitoneal injection of DMSO(consistent with the dissolved dose of EGCG).The action of intraperitoneal injection was taken but nothing was injected in the untreated group.The mice were treated 5 days per week and heart tissue was collected in each group 3 months after the treatment.cTnI expression,mRNA expression of cTnI,GATA4 and HDAC1,H3K9 histone acetylation the binding of HDAC1 and GATA4 in cTnI promoter region were tested by Western blot,RT-PCR and Ch IP-Q-PCR.ResultsThe normal cTnI in EGCG group were significantly higher in R193H-restricted cardiomyopathy model mice than that in DMSO group and untreated group(P <0.05),whereas no differences were found in normal wild-type C57 mice.RT-PCR results showed increased expression level of mRNA of GATA4 and decreased expression level of mRNA of HDAC1 in EGCG treatment group in R193 H mice compared with that in DMSO group and untreated group(P <0.05).ChIP-Q-PCR results showed higher histone acetylation level of H3K9,lower binding level of HDAC1 and higher binding level of GATA4 in the cTnI promoter region in EGCG treatment group in R193 H mice compared with that in DMSO group and untreated group(P <0.05).ConclusionBy inhibiting HDAC1 expression level and the binding level of HDAC1 with cTnI gene promoter region,EGCG increases the histone acetylation level of H3K9,the expression level of cardiac transcription factor GATA4,as well as the binding level of GATA4 in cTnI promoter region,thereby reversing the low expression of normal cTn I in myocardium of restrictive cardiomyopathy.