The Role And Mechanism Of Pyruvate Kinase 2(PKM2) In Cardiac Hypertrophy

Objective: Pyruvate kinase(PK)is a key rate-limiting enzyme that catalyzes the final step of glycolysis,catalyzing the conversion of dephosphorylated phosphoenolpyruvate to pyruvate for energy production.PK includes four isoenzymes(PKL,PKK,PKM1,PKM2),of which PKM2 mainly exists in early embryonic tissues,and is also high in tumor tissues and myocardial tissues under pathological conditions such as tumors,myocardial hypertrophy,and heart failure.expression.At present,PKM2 can be used as a metabolic rate-limiting enzyme to participate in energy metabolism and as a protein kinase to regulate cell proliferation.Its research in tumor cells has been relatively clear,but its role in the heart remains unknown.Therefore,our research team used constructing an animal model of myocardial hypertrophy and introducing mice with specific overexpression of PKM2 as a vector,exploring the correlation between PKM2 expression and myocardial hypertrophy,understanding the mechanism of PKM2 participating in myocardial hypertrophy,and providing treatment for preventing myocardial hypertrophy New target ideas.Methods:(1)Wild C57 BL / 6J male mice were selected.Aortic constriction(TAC)was used to establish a model of myocardial hypertrophy in mice and the sham group was used as a control.Echocardiographic examination of mice was performed to evaluate changes in left ventricular diameter,left ventricular posterior wall thickness,and interventricular septal thickness,and it was confirmed that the mice had significant cardiac hypertrophy.(2)The protein levels of PKM2 and myocardial hypertrophy markers(ANP,Myh7)in myocardial tissue were detected by Western blot at 2,4,and 6 weeks after operation,and the time points of significant expression of PKM2 were found.(3)Using a specific PKM2 overexpression(PKM2-KI)C57BL / 6J male mouse as the research background,and after PCR identification,aortic constriction was also used to establish a myocardial hypertrophy model in PKM2 overexpressing mice.Echocardiography was used to evaluate the left ventricular diameter,left ventricular posterior wall thickness,and left ventricular thickness.HE staining was used to measure the cross-sectional area of cardiomyocytes.Cardiac hypertrophy,glycolytic pathway,and Akt / m TOR signaling pathway were detected by Western blot.To evaluate the role and mechanism of PKM2 in regulating myocardial hypertrophy.Results:(1)The establishment of a model of myocardial hypertrophy: the results of echocardiographic examination: the thickness of the ventricular septum and the thickness of the posterior wall of the left ventricle increased significantly,and the diameter of the left ventricle decreased significantly at the end of diastole.Heart and lung mass increased significantly.Western blot detection of myocardial hypertrophy factor ANP,Myh7 protein expression was significantly up-regulated(n = 8,p<0.05)(2)Find the time point of significant PKM2 expression: 6 weeks after TAC,PKM2 expression in mouse cardiomyocytes was the most significant(n = 3-5,p<0.05).(3)Explore the role and mechanism of PKM2 in regulating myocardial hypertrophy:Compared with WT TAC,the expression of myocardial hypertrophy factor ANP and Myh7 in the PKM2-KI TAC group was significantly increased(n = 3-5,p<0.05);glycolytic pathway Key protein lactate dehydrogenase(LDBH)expression was significantly up-regulated(n = 3-5,p<0.05);Akt / m TOR signaling pathway key proteins m TOR and P-Akt expression were significantly down-regulated(n = 3-5,p<0.05),P-m TOR has a downward trend(n = 3-5,p>0.05).HE staining measured the cross-sectional area of cardiomyocytes.Compared with the WT TAC group,the cross-sectional area of cardiomyocytes in the PKM2-KI TAC group was significantly increased(n = 3-5,p<0.05).Conclusion: 1.The expression of PKM2 is increased in the myocardial hypertrophy model established by TAC,and the expression is most significant at 6W after TAC 2.Overexpression of PKM2 gene will aggravate pathological cardiac hypertrophy 3.PKM2 regulates the occurrence and development of cardiac hypertrophy through glycolysis pathway 4.Akt / m TOR signaling pathway is inhibited when PKM2 is overexpressed...