Biological And Mechanical Coupling Mechanism Study Of Histone Deacetylase 1 Inhibition Protects Against Hypoxia Induced Swelling In Cardiomyocytes

Myocardial edema is a frequently detectable incident in the acute phase of myocardial ischemia and other pathological situations.Numerous elements are involved in volume regulation of cardiomyocytes,including osmotic forces,channels,cell volume sensing,intracellular water distribution and so on.Although a series of studies displayed that gene profile changed in swelling cardiomyocyte,the mechanism of the pathological process was still not completely elaborated.Epigenetic modification could have an influence on histone,then change gene expression level in virtue of histone acetyltransferase(HATs)and histone deacetylase(HDACs).HDAC4 inhibition increased the resistance of cardiomyocytes in response to hypoxia/reoxygenation,as evidenced by an increased cell survival and reduction of cytotoxicity,and an anti-apoptotic effect.Besides,Under hypoxic situations,the expression level and activity of HDAC1 are obviously increased in tumor cell lines.However,whether HDAC1 is able to control the volume of cardiomyocyte has not been investigated.The process of cell swelling involves physical transformation and changes of gene profile,which interact with each other.In the light of our present knowledge,mechanical property of swelling cardiomyocyte has not been studied,as well as mechanics mechanism involved in expansion process.Therefore,establishing the study to gain an insight into the effect of histone acetylation in swelling cardiomyocyte may contribute to absolutely reveal the molecular biology mechanism of myocardial edema.To investigate the mechanical property of swelling cardiomyocyte and its biological and mechanical coupling mechanism will provide us a new perspective to understand the pathological mechanism of myocardial edema.In present study,we established H9c2 cardiomyocyte cobalt chloride(CoCl2)chemical hypoxia model,in vitro.By using classical molecular biology experiment methods,we screened and validated effect of HDAC1 in early stage of myocardial cell edema,and explored its molecular biology mechanism.Based on atomic force microscopy(AFM)and theoretical physics related principle,the mechanical property of swelling cardiomyocyte and its biological and mechanical coupling mechanism was studied.Encouragingly,some excellent research achievements were obtained.(1)CoCl2 induced cell damage,apoptosis,oxidative stress imbalance,cytoskeleton remodeling and acetylation level of H3,H4 histone decline in H9c2 cardiocytes.Results of western blot showed that CoCl2 treatment did not change expression level of HAT1 and HDAC4,but chemical hypoxia upregulated expression level of HDAC1.The data suggests that HDAC1 play an important role in early stage of myocardial edema.(2)HDAC1 inhibition(RNAi and HDAC1-selective inhibitor)attenuated cell damage,apoptosis,oxidative stress imbalance,cytoskeleton remodeling and acetylation level of H3,H4 histone decline in swelling H9c2 cardiocytes induced by CoCl2.Results of western blot showed that CoCl2 treatment downregulated expression level of Akt,pAkt,P38,pP38,Bcl-2,and upregulated expression level of P53,Bax,Caspase3 and AQP1.But,HDAC1 inhibition downreglated expression level of Akt,pAkt,P38,pP38 and AQP1.These findings suggest that HDAC1 inhibition protects against hypoxia induced swelling in cardiomyocytes.Its molecule mechanism may be HDAC1 mediated histone acetylation reverses abnormal expression of proteins in PI3K/Akt,p38 MAPK signaling pathway.(3)Chemical hypoxia declined Young’s modulus in H9c2 cardiocytes,upregulated granularity and cell volume.Based the empirical equation and ideal physical model,cell stiffness is a critical factor in process of myocardial edema.HDAC1 inhibition protects against hypoxia-induced swelling in H9c2 cardiomyocytes through increasing Young’s modulus of the cell.In conclusion,HDAC1 mediated histone acetylation may be a vital elements to myocardial edema.HDAC1 inhibition protects against hypoxia-induced swelling in H9c2 cardiomyocytes through increasing proliferation,attenuated cell damage,apoptosis,oxidative stress imbalance and so on.Its molecule mechanism may be related to maintain normal expression of many genes which are involved in multiple signaling pathway,including PI3K/Akt,p38 MAPK.What’ s more,cell stiffness is also a key factor in myocardial edema.HDAC1 inhibition regulates cell structure and motility-related genes in swelling H9c2 cardiomyocytes,and reverses disorganization and signal intensity decrease of cytoskeleton actin,thereby enhances stiffness of swelling H9c2 cardiomyocytes.Thus,the mechanism of HDAC1 inhibition protective effect in swelling H9c2 cell is probably biological and mechanical coupled.