Effects Of A Bout Of Treadmill Exercise On MEF2 Protein Expression By Induced AMPK In Mice Skeletal Muscle

As an energy sensor at cellular level, AMPK (5'-AMP-activated protein kinase) activation is able to increase the expression of GLUT4 (glucose transporter 4). MEF2 (myocyte enhancer factor 2) proteins are a family of transcriptional factors that play a vital role in the regulation of GLUT4 gene transcription by binding GLUT4 gene promoter. Both AMPK and MEF2 affect GLUT4 gene expression, but there are different sights about the relationship of AMPK and MEF2 at present. The purpose of this study was to determine the effects of a bout of treadmill exercise on the expression of MEF2 protein by induced AMPK in mice skeletal muscle, providing a theoretical basis for deep study in energy metabolism during exercise.Methods:Wild-type (WT) mice, transgenic (TG) mice of AMPK a 2 over-expression and AMPKa 2 knockout(KO) mice, were randomly divided into Control group and Exercise group separately,10 of each. Control group had none exercise load, Exercise group had undertaken one-hour treadmill exercise with 12m/min of speed and 0°grade.3h after the end of exercise, quadriceps were removed and MEF2 protein expressions were measured.Results:(1) MEF2 protein expression in whole cell:there was no significance difference between Control group and Exercise group, or among WT, TG and KO mice (p>0.05); (2) MEF2 protein and phosphated MEF2 protein expressions in nucleus of Exercise group were significantly higher than Control group in WT/TG/KO mice (p<0.01); (3) MEF2 protein and phosphated MEF2 protein expressions in nucleus:whether at rest or after exercise, there was no significant difference among WT, TG and KO mice (p>0.05).Conclusion:(1) This bout of treadmill exercise significantly increased MEF2 protein and phosphated MEF2 protein expressions in nucleus, but almost had no effect on total MEF2 protein expression in whole cell of mice skeletal muscle; (2) After this exercise, compared with MEF2 protein expressions of WT mice, those of TG/KO mice weren't significantly different,suggesting that AMPKa 2 didn't affect MEF2 protein expressions in nucleus/whole cell of mice skeletal muscle after a bout of treadmill exercise, and that other pathways might participate in the regulation of MEF2.