Effects Of Endurance Training Inducing AMPK On Protein Expression Of PP38and P-MEF2in Skeletal Muscle Of Mice

It is well established that activation of AMPK will increase the expression of GLUT4protein. However, how AMPK regulates the expression of the GLUT4is still obscure. It is reported that the MEF2is one of the necessary factors that play a vital role in GLUT4gene transcription. As a family member of MAPK, p38MAPK can activate MEF2by way of phosphorylation and thus greatly enhance the transcriptional activity of MEF2. At the same time, AMPK can activate the downstream p38MAPK and turn it into its active form-pp38.Objective: This paper is aimed to probe into the role of AMPK in regulating expression of p38, pp38and p-MEF2A induced by endurance treadmill exercise.Methods: Wild-type (WT) mice, AMPK a2over-expressing transgenic(TG) mice and AMPKa2knockout (KO) mice were randomly divided into Control group and Endurance Exercise group by weight. The control group had not been exerted any exercise load while the exercise group had undertaken one-hour treadmill exercise with an intensity of12m/min.12h after finishing the final exercise, quadriceps were removed and p38, pp38and p-MEF2A protein expressions were measured by Western Blot.Results:1) Compared to the control group, the overall pp38protein expression of the three kinds of AMPK α2mice after four-week endurance training significantly increased. In addition, the pp38and pp38protein expression of TG mice increased compared to the WT mice. Although the pp38protein expression of KO mice is lower than the WT mice, there’ s no significant difference.2) After endurance training, p-MEF2A content in muscle cell nucleus of different groups increase significantly compared to the control group and the nucleus p-MEF2A expression of TG mice was significantly higher than the WT mice while there’s no significant difference between KO mice and WT mice.3) The phosphorylation activity of p38and MEF2A in the skeletal muscle of42mice are highly positive correlated (r=0.69, P<0.05). Conclusion:Although the effect of endurance training on p38protein expression’is not significant, endurance training can greatly promote the phosphorylation activity of p38and MEF2A. However, the data also suggests that perhaps AMP α2is not the only pathway to activate p38as well as MEF2A. The phosphorylation activity of p38is closely related to the promotion of transcriptional activity of MEF2A by phosphorylated MEF2A.