Effects of Exercise with Different Intensity on the Content of MEF2A Bounding to the GLUT4 Promoter in Skeletal Muscle of AMPKα2-WT/KO/OE Mice

Purpose:The role of AMPK in regulating the exercise induced MEF2A binding to the GLUT4 promoter, and GLUT4 mRNA expression was investigated.Methods:Wild-type (WT;n=30) , AMPKα2 over-expression (OE;n=30) , and AMPKα2 knockout (KO;n=30) C57/BL mice were randomly divided into three groups:control group, low-intensity (12m/min) group and high-intensity (20m/min) group.Mice were killed after 3h of treadmill running completed by 60 min of continuous running on the experimental day.1) AMPKα-Thr172 phosphorylation by western blot.2) Total and nuclear MEF2A by western bolt.3) Bound MEF2A at the GLUT4 MEF2 cis-e, m lement by CHIP.4) GLUT4 expression by Real Time-PCR and Western blot.Results:Over-expression of AMPKα2, which was associated with higher AMPKα-P in exercise muscles, heightens the exercise-induced increase in MEF2A binding to the GLUT4 promoter and GLUT4 mRNA expression.Exercise-induced increases of GLUT4 mRNA expression, were normal in α2-KO muscles despite the reduced AMPK signaling and GLUT4 promoter-bound MEF2A.Conclusion:1) Exercise increases Glut4 expression by increase the binding of MEF2A to the Glut4 promoter.2) Exercise increases the binding of MEF2A to their binding sites on the Glut4 gene by an AMPK-dependent mechanism.3) AMPK activity during exercise is not indispensable for expression of GLUT4.