Effects And Mechanism Of RGS5 On Ventricular Remodeling After Myocardial Infarction In Mice

Research backgroundMyocardial infarction is one of the major causes of death and disability worldwide,about 1/3 of the world's patients is caused by it.A major coronary artery occlusion can cause severe myocardial ischemia and rapid apoptosis and inflammatory reaction of cardiomyocytes,which leads to progressive fibrosis instead of myocardial tissue and expansion of left ventricle.Progressive left ventricular remodeling can lead to heart failure after myocardial infarction,and the prognosis of patients with heart failure is still not optimistic.Therefore,how to effectively reduce the ventricular repurchase after myocardial infarction is a new hope for the treatment of ischemic heart disease.G protein signal regulator 5(RGS5)is a negative G protein mediated signal regulator,is highly expressed in the murine animal and human adult heart in different cells,embryonic development,wound healing and reproductive cycle plays a role in the process of maintenance,and participate in angiogenesis,vascular adventitial cell maturation and myocardial repolarization this polarization,hypertension,atherosclerosis,arrhythmia and myocardial ischemia reperfusion injury in the pathogenesis.Role RGS5,however,cardiac function and myocardial remodeling after myocardial infarction is not clear.Therefore,we have designed this experiment to study the effect of RGS5 on cardiac function and cardiac remodeling in mice after myocardial infarction and the mechanism of its effect.Part one The effect of part one RGS5 on inflammatory response,apoptosis and myocardial fibrosis after myocardial infarction in mice and its mechanismObjective:More and more evidences show that inflammatory reaction and apoptosis play an important role in ventricular remodeling after myocardial infarction and promote the occurrence of heart failure.The aim of this study was to explore the effects of RGS5 on the inflammatory response,apoptosis and myocardial fibrosis after myocardial infarction in mice and to explore the possible mechanisms.Methods:The myocardial infarction model was established by ligating the anterior descending coronary artery of the C57BL/6 mice and the RGS5 gene knockout mice(RGS5 KO).The myocardial infarction model was divided into 4 groups:the C57BL/6 sham operation group(WT sham),the C57BL/6 operation group(WT MI),the RGS5 KO sham operation group(RGS5 KO sham),and the RGS5 surgery group.The Western blot method was used to detect the expression of RGS5 in the myocardium of the infarcted myocardium.Using TTC staining method to calculate myocardial infarction 1 days after infarction area;using HE and Masson staining was used to determine the degree of myocardial injury;to calculate changes in 7 days after infarction using mouse heart function function ultrasonic detection method;using TUNEL(terminaldeoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assayTUNEL)7 day Myocardium Apoptosis.Detection cells after myocardial infarction.RT-PCR was used to determine the expression of inflammatory factors(TNF-a,IL-1 beta,IL-6),myocardial fibrosis markers(CTGF,collagen I,and collagen III).Using Western blot the expression of RGS5,T-I B,P-I kappa B alpha kappa alpha,T-p65,P-p65,T-p38,P-p38,T-JNK1/2,P-JNK1/2,T-ERK1/2 and P-ERK1/2 measured after MI.Results:The study showed that compared with WT group,RGS5 gene deletion mice after MI significantly reduced the survival rate and the function of left ventricle(LV),and increased the infarct size.In addition,RGS5 knockout mice showed greater inflammation,apoptosis and ventricular remodeling,such as TNF-a,IL-1,IL-6,TUNEL staining and Bax/Bcl-2 ratio,and the expression of myocardial fibrosis markers(CTGF,collagen 1,and collagen).In mechanism,the pathological response of RGS5 deletion activation is mainly caused by the NF-kappa B and MAPK signaling pathways,such as phosphorylated p65 and I kappa B alpha level,ERK1/2 phosphorylation level,JNK1/2 and p38 levels increase significantly in RGS5-KO mice.Conclusions:This study confirms that RGS5 plays a protective role in inflammatory response,apoptosis and myocardial fibrosis after myocardial infarction in mice,and its mechanism is induced by NF-kappa B and MAPK signaling pathway.Part two The effect of the second part of RGS5 on ventricular remodeling and cardiac function after myocardial infarction in mice and its mechanismObjective:To explore the effect and mechanism of RGS5 on ventricular remodeling and cardiac function after myocardial infarction in mice through vascular regenerationMethods:The myocardial infarction model was established by ligating the anterior descending coronary artery of the C57BL/6 mice and the RGS5 gene knockout mice(RGS5 KO).The myocardial infarction model was divided into 4 groups:the C57BL/6 sham operation group(WT sham),the C57BL/6 operation group(WT MI),the RGS5 KO sham operation group(RGS5 KO sham),and the RGS5 surgery group.The parameters of ejection fraction,short axis shortening,end-end diastolic diameter and end systolic diameter were evaluated by ultrasonic electrocardiogram.The morphological changes of myocardial tissue were observed by HE staining.The percentage of myocardial infarction in each group was calculated,and the degree of myocardial fibrosis in each group was evaluated by Masson staining.The TUNEL method was used to detect the degree of apoptosis in all the mice.CD31 immunohistochemical staining was used to evaluate the angiogenesis in the myocardium of the experimental mice by comparing with the microvascular density in the surrounding area of the model group.The expression of PI3K/AKT,VEGF and eNOS protein in the myocardium of mice was observed by Western blot.The content of HIF-a in cardiac myocytes was detected by EMSA.Results:The results showed that the study shows that with WT group mice compared with MI in RGS5 deficient mice significantly reduced microvessel density after myocardial infarction to revascularization decrease,deterioration of heart function and reduce the apoptosis rate of myocardial cells,such as CD31 labeled microvessel density decreased,TUNEL staining and myocardial fibrosis the extent of the increase of CSA value.In addition,deletion of RGS5 gene decreased the phosphorylation of Akt reduced extracellular signal regulated kinase(ERK),endothelial nitric oxide synthase(eNOS),phosphatidylinositol-3 kinase(PI3K),hypoxia-induciblefactorsl(HIF-la)and vascular endothelial growth factor(VEGF)expression,and decreased after myocardial infarction HIF-1 alpha with DNA binding activity.Conclusions:RGS5 gene deletion by reducing angiogenesis deterioration of the heart function and promote ventricular remodeling the deletion of RGS5 gene can inhibit the angiogenesis of the important factor PI3K/Akt,ERX,HIF-1,?VEGF and P-eNOS,indicating that the heart protective effect of RGS5 is accomplished through angiogenesis signaling pathway.