AMP kinase is not required for the GLUT4 response to exercise and denervation in skeletal muscle.
An acute bout of exercise increases muscle GLUT4 mRNA in mice, and denervation decreases GLUT4 mRNA. AMP-activated protein kinase (AMPK) activity in skeletal muscle is also increased by exercise, and GLUT4 mRNA is increased in mouse skeletal muscle after treatment with AMPK activator 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside(AICAR). These findings suggest that AMPK activation might be responsible for the increase in GLUT4 mRNA expression in response to exercise. To investigate the role of AMPK in GLUT4 regulation in response to exercise and denervation, transgenic mice with a mutated AMPK alpha-subunit (dominant negative; AMPK-DN) were studied. GLUT4 did not increase in AMPK-DN mice that were treated with AICAR, demonstrating that muscle AMPK is inactive. Exercise (two 3-h bouts of treadmill running separated by 1 h of rest) increased GLUT4 mRNA in both wild-type and AMPK-DN mice. Likewise, denervation decreased GLUT4 mRNA in both wild-type and AMPK-DN mice. GLUT4 mRNA was also increased by AICAR treatment in both the innervated and denervated muscles. These data demonstrate that AMPK is not required for the response of GLUT4 mRNA to exercise and denervation.
Holmes
Burton F
BF
East Carolina University, Greenville, NC 27858, USA.
Lang
David B
DB
Birnbaum
Morris J
MJ
Mu
James
J
Dohm
G Lynis
GL
D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D002374:Catalase / Q000096:biosynthesis; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000502:physiology*; D020536:Enzyme Activators / Q000494:pharmacology; D051275:Glucose Transporter Type 4; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000096:biosynthesis; D051379:Mice; D008822:Mice, Transgenic; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis*; D009121:Muscle Denervation; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000378:metabolism*; D023282:Nuclease Protection Assays; D005082:Physical Exertion / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012265:Ribonucleotides / Q000494:pharmacology
D020536:Enzyme Activators; D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; D012265:Ribonucleotides; C495693:Slc2a4 protein, mouse; D000620:Aminoimidazole Carboxamide; D002374:Catalase; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D017868:Cyclic AMP-Dependent Protein Kinases; C031143:AICA ribonucleotide