| Objective: To investigate the effect of anacardic acid(AA),an inhibitor of histone acetyltransferases(HATs),on the acetylation of H4K16 ac mediated by histone acetyltransferase KAT8,which attenuates myocardial fibrosis in mice after thoracic aortic constriction(TAC),and the overexpression of fibrosis related proteins in the process of myocardial fibrosis in TAC mice.Methods: SPF grade KM mice of 6-8 weeks were chose as the experimental subject.Group the experimental animals according to the principle of random number table:normal group,sham group,vehicle group,thoracic aortic coarctation(TAC)group and thoracic aortic coarctation + anacardic acid(TAC + AA)group.In TAC group,transverse aortic coarctation was performed to construct the myocardial fibrosis model induced by pressure overload.Sham group only isolated the thoracic aorta of mice without ligation.TAC + AA group was given intraperitoneal injection of AA(5 mg/kg,3 times/week)afte one week TAC operation,which lasted until 12 weeks after TAC operation.Vehicle group was given intraperitoneal injection of DMSO(5mg/kg,3 times/week)after one week TAC operation,which lasted until 12 weeks after TAC operation.The following experiments were performed on mice hearts after 12 weeks surgery:(1)Ultrasonic Doppler was used to evaluate the effect of operation,observe the ligation site,detect the diameter of aorta and blood flow velocity;(2)The morphology of the heart and the degree of myocardial tissue fibrosis were observed by masson staining;(3)Western blot was used to detect H4K16 ac acetylation level,and protein expression of KAT8,H4K16 ac,TGF-β1,SMAD3,Collagen I,and Collagen Ⅲ;(4)The interaction between KAT8 and H4K16 ac was detected by immunocoprecipitation.Results:(1)Echocardiography showed that it was stenosis occurred at the ligation site of aortic arch between innominate artery and left carotid artery in TAC group.At the same time,compared with Sham group,the diameter of aortic arch ligation was significantly reduced in TAC group(P < 0.05),and the blood flow velocity was significantly faster in TAC group(P < 0.05).(2)Masson staining results showed that compared with the Sham group,the heart of mice in TAC group was significantly enlarged,and the collagen and fibrosis in myocardial tissue increased,while the hearts of mice in TAC + AA group were smaller than those in TAC group,the collagen and fibrosis in myocardium were reduced.There was no significant change in the above indexes in sham group compared with normal group and TAC group compared with vehicle group.(3)WB results showed that the expression levels of histone acetylase KAT8 and H4K16ac acetylated protein in TAC group were significantly higher than those in sham group(P < 0.05),The protein expression levels of TGF-β1,SMAD3,collagen I and collagen III were significantly higher than those in sham group(P <0.05).Compared with TAC group,AA decreased the protein overexpression of KAT8 and the high acetylation of H4K16 ac in the hearts of TAC mice(P < 0.05).Meanwhile,in TAC + AA group,the protein expressions of TGF-β1,SMAD3,collagen I and collagen III decreased compared with TAC group(P < 0.05).There was no significant difference in the above indexes between sham group and normal group,TAC group and vehicle group(P > 0.05).(4)The results of Co IP showed that KAT8 could bind to H4K16 ac.Conclusions:(1)KAT8 mediated hyperacetylation of histone H4K16 ac may be regulate TGF-β1/SMAD3 signaling pathway participates in myocardial fibrosis in TAC mice(2)AA may inhibit the hyperacetylation of histone H4K16 ac mediated by KAT8 and affect the expression of TGF-β1/SMAD3 signaling pathway,thus improving the myocardial fibrosis induced by thoracic aortic constriction in mice.Objective: To investigate the histone acetylation mechanism of histone acetylase inhibitor anacardic acid(AA)improved myocardial systolic dysfunction and the survival rate in thoracic aortic coarctation(TAC)mice.Methods: SPF grade KM mice of 6-8 weeks were chose as the experimental subject.Group the experimental animals according to the principle of random number table:normal group,sham group,vehicle group,thoracic aortic coarctation(TAC)group and thoracic aortic coarctation + anacardic acid(TAC + AA)group.In TAC group,transverse aortic coarctation was performed to construct the myocardial fibrosis model induced by pressure overload.Sham group only isolated the thoracic aorta of mice without ligation.TAC + AA group was given intraperitoneal injection of AA(5 mg/kg,3 times/week)after one week TAC operation,which lasted until 12 weeks after TAC operation.Vehicle group was given intraperitoneal injection of DMSO(5mg/kg,3 times/week)after one week TAC operation,which lasted until 12 weeks after TAC operation.The following experiments were performed on mice hearts after 12 weeks surgery:(1)The thickness of ventricular wall and the size of left ventricular cavity were measured by mouse heart ultrasound;Left ventricular systolic indices were measured at three cardiac cycles using an M-shaped parastrosternal short axis view.(2)Western blot was used to detect the core transcription factor GATA4 and cardiac systolic and diastolic related regulatory proteins c Tn I and β-MHC protein expression.(3)Co IP detected the interaction between H4K16 and GATA4.(4)The survival rate of mice was observed.Results:(1)The results of cardiac color ultrasound showed that the thickness of left ventricular posterior wall(LVPWT)and systolic anterior left ventricular anterior wall(LVAWT)in TAC group were significantly thinner and the left ventricular volume(LVV)was significantly increased than that in sham group(P < 0.05).After AA treatment,the thickness of LVPWT and systolic anterior LVAWT in TAC group were thicker and the LVV was decreased(P < 0.05).After operation,the LVEF of TAC mice was significantly lower than that of sham group(P < 0.05),and the LVEF of AA intervention group was higher than that of TAC group(P < 0.05).There was no significant difference in these indexes between sham group and normal group,TAC group and vehicle group(P > 0.05).(2)WB results showed that GATA4,c Tn I and β-MHC of the protein expression were higher than that of sham group(P < 0.05).Compared with TAC group,GATA4,c Tn I and β-MHC of the protein expression of MHC were lower than that of TAC group(P < 0.05).There was no significant difference in these indexes between sham group and normal group and TAC group and vehicle group(P > 0.05).(3)The results of Co IP showed that H4K16 could bind to GATA4.(4)The survival rate of TAC mice was significantly improved by AA.Conclusions:(1)AA can improve the cardiac function of TAC mice,which via inhibiting KAT8 mediated hyperacetylation of histone H4K16 ac and affecting the protein expressions of core transcription factor GATA4 and related regulatory proteins c TNI and β-MHC in the hearts of mice.(2)AA may improve the survival rate of TAC mice by regulating KAT8 mediated hyperacetylation of H4K16 ac. |
