The Mechanism Of Deacetylase HDAC3 Involved In The Occurrence Of Cardiomyopathy

Objective:Cardiomyopathy is a genetic or acquired disease.Due to myocardial injury and changes in myocardial structure and function,the myocardium contraction is weakened,resulting in reduced blood output of the heart,which cannot meet the blood supply required by the metabolism of the body tissues.This is a progressive and irreversible process.HDAC3protein,on the one hand,acts as a histone deacetylase on histones to inhibit histone deacetylation and inhibits gene expression,on the other hand,it forms an inhibitory complex with NCo R/SMRT to inhibit gene expression.Studies have found that HDAC3 participates in liver lipid metabolism and does not depend on the activity of deacetylase.The cardiac-specific HDAC3 knockout caused myocardial lipid metabolism disorders,which leads to decreased cardiac contractility in mice.However,whether the involvement of HDAC3 in cardiomyopathy depends on the molecular mechanism of deacetylase activity remains unclear.This topic aims to further clarify the molecular mechanism of the deacetylase HDAC3 in the occurrence and development of cardiomyopathy.Methods:First,the cardiac-specific driver Hand-Gal4 was used to specifically knock down（KD）the expression of HDAC3 in the Drosophila heart.The Drosophila adult heart physiology function analysis platform analyzes various physiological indicators of the Drosophila heart,including systolic interval,diastolic interval,heart period,systolic diameter,diastolic diameter,arrhythmia index and fractional shortening representing myocardial contractility.Phalloidin staining was used to observe the changes in the morphological structure of the Drosophila heart.Survival curve analysis to view the lifespan of Drosophila.DHE staining was used to observe the level of ROS in the nucleus of Drosophila cardiomyocytes.The TAG kit detects the TAG content in the Drosophila heart.Western blot and immunofluorescence staining were used to detect the expression level of extracellular matrix protein pericardin in Drosophila heart.RT-q PCR technology detects the expression level of HDAC3 target genes in the Drosophila heart.Results:Compared with the control group,（1）the cardiac-specific HDAC3 KD resulted in prolonged diastolic interval（P<0.05）and significantly decreased myocardial contractility of Drosophila heart（P<0.001）.（2）The cardiac-specific HDAC3 KD caused half of the Drosophila to have myocardial fiber injury defects.（3）The lifespan of the cardiac-specific HDAC3 KD Drosophila was significantly shorter（P<0.0001）.（4）The cardiac-specific HDAC3 KD did not change the ROS level in the Drosophila heart,but caused the triglyceride TAG in the heart of Drosophila to increase（P<0.05）and the expression of the extracellular matrix protein pericardin was significantly increased（P<0.01）.（5）The cardiac-specific HDAC3 KD resulted in decreased expression of Drosophila heart structural genes MSP300,TPNC25D and cardiac lipid metabolism transcription factor Smr,ATF3（P<0.05）.Compared with the normal food,high-fat diet also resulted in down-regulation of the above-mentioned genes in the control Drosophila heart.（6）The HDAC3deacetylase activity mutant HDAC3^K26A transgene partially rescues the decreased cardiac contractility,myocardial fiber damage and myocardial fibrosis phenotype caused by HDAC3 KD.Conclusion:（1）Cardiac-specific HDAC3 KD leads to decreased myocardial contractility,myocardial fiber damage and shortened lifespan in Drosophila.（2）Cardiac-specific HDAC3 KD did not affect the ROS level of Drosophila heart,causing the increase of TAG level and extracellular matrix protein pericardin,and myocardial fibrosis.（3）Cardiac-specific HDAC3 KD resulted in down-regulated expression of Drosophila myocardial structural genes TPCN25D and MSP300,as well as down-regulated expression of lipid metabolism-related transcription factors Smr and ATF3,which may be associated with decreased cardiac contractility and increased TAG.High-fat diet also resulted in the down-regulation of the above heart genes in Drosophila,suggesting that high-fat diet and HDAC3 KD may lead to the occurrence of cardiomyopathy through affecting the same downstream signaling pathway.（4）The involvement of HDAC3 in the occurrence of cardiomyopathy is independent of its deacetylase activity.