The Roles And Molecular Mechanisms Of MICAL2 In The Cardiac Hypertrophy Induced By Angiotensin ?

Objective: Cardiac hypertrophy is a structural and functional alterations of the heart that occurs under various CVD conditions such as hypertension and is characterized by an increase in cardiomyocyte volume,sarcomeric hyperplasia,and the reactivation of fetal genes.However,the inhibitory factors associated with cardiac hypertrophy have not been fully understood yet,which needs further study and is helpful to understand the pathogenesis of cardiac hypertrophy and explore potential targets.To explore the inhibitory factors associated with cardiac hypertrophy is an important direction in the field of cardiovascular biology research and is also an effective strategy to develop new methods of intervention and treatment of CVD.MICAL2 protein belongs to the MICAL family and is expressed in many tissues such as the heart.MICAL2 has the activity of flavoprotein monooxygenase,which means that under the action of coenzyme NADPH,MICAL2 protein produces more H2O2 and plays a varieties of biological functions.Previous studies have shown that the MICAL family can not only regulate the normal development of bristles growth of Drosophila,dendritic spine construction,axon guidance and hippocampal mossy fiber connection,but also participate in the pathogenesis of tumorigenesis,cerebral ischemia,spinal cord injury,epilepsy and other pathological processes,however,its roles and mechanisms in the occurrence and development of cardiac hypertrophy have not been reported yet.Methods: In this study,healthy and female Kunming mice were randomly divided into normal saline-infused group and Ang ?-infused group(8 mice in each group),and treated with saline or Ang ? for 2 weeks by Alzet osmotic pumps,the ultrasound Doppler technology,histomorphology technology and the detection of molecular markers were used to evaluate if the mouse model of Ang?-induced cardiac hypertrophy was established successfully.Western blot,immunohistochemistry and qPCR were used to detect the expression of MICAL2 in cardiac hypertrophy.The constructed plasmid of MICAL2 gene and control plasmid were transfected into cardiomyocytes and stimulated by Ang ?,then the degree of hypertrophy of cardiomyocytes was detected by immunofluorescencet,the ROS level of cardiomyocyte and HDAC2 activity were detected by fluorescent probe and microplate reader.The level of acetylation and phosphorylation of HDAC2 protein were detected by Western blot,and the effect of MICAL2 expression on the interaction between HDAC2 and CK2?1 was detected by co-immunoprecipitation assay.Results: 1.The significant pathological process of cardiac hypertrophy had been induced by Ang ? stimulation;2.Compared with the control group,both of mRNA level and protein level of MICAL2 gene in hypertrophic myocardium were down-regulated significantly,meanwhile,the expression level of MICAL2 protein in cardiomyocytes stimulated by Ang ? was also decreased significantly;3.Overexpression of MICAL2 protein can block the cardiomyocyte hypertrophy induced by Ang ?;4.Overexpression of MICAL2 protein could significantly increase the level of ROS in cardiomyocytes and thereby decreasing HDAC2 activity and increase the acetylation level of histone H3;5.MICAL2 can compete with HDAC2 to affect the interaction between HDAC2 and CK2?1,and then decreased the phosphorylation level of HDAC2-S394.Conclusion: MICAL2 protein is abnormally expressed in hypertrophic myocardium induced by Ang ?,and can negatively regulate the hypertrophy of cardiomyocytes induced by Ang ?.In one hand,MICAL2 inhibits the activity of HDAC2 through its own flavin monoxynase enzyme activity,on the other hand,MICAL2 can competitively inhibit the interaction between HDAC2 and CK2?1,and reduce the phosphorylation level of HDAC2-S394,finally exerting the effect of inhibiting Ang ?-induced cardiomyocyte hypertrophy.