Effects of alpha-AMPK knockout on exercise-induced gene activation in mouse skeletal muscle.
We tested the hypothesis that 5'AMP-activated protein kinase (AMPK) plays an important role in regulating the acute, exercise-induced activation of metabolic genes in skeletal muscle, which were dissected from whole-body alpha2- and alpha1-AMPK knockout (KO) and wild-type (WT) mice at rest, after treadmill running (90 min), and in recovery. Running increased alpha1-AMPK kinase activity, phosphorylation (P) of AMPK, and acetyl-CoA carboxylase (ACC)beta in alpha2-WT and alpha2-KO muscles and increased alpha2-AMPK kinase activity in alpha2-WT. In alpha2-KO muscles, AMPK-P and ACCbeta-P were markedly lower compared with alpha2-WT. However, in alpha1-WT and alpha1-KO muscles, AMPK-P and ACCbeta-P levels were identical at rest and increased similarly during exercise in the two genotypes. The alpha2-KO decreased peroxisome-proliferator-activated receptor gamma coactivator (PGC)-1alpha, uncoupling protein-3 (UCP3), and hexokinase II (HKII) transcription at rest but did not affect exercise-induced transcription. Exercise increased the mRNA content of PGC-1alpha, Forkhead box class O (FOXO)1, HKII, and pyruvate dehydrogenase kinase 4 (PDK4) similarly in alpha2-WT and alpha2-KO mice, whereas glucose transporter GLUT 4, carnitine palmitoyltransferase 1 (CPTI), lipoprotein lipase, and UCP3 mRNA were unchanged by exercise in both genotypes. CPTI mRNA was lower in alpha2-KO muscles than in alpha2-WT muscles at all time-points. In alpha1-WT and alpha1-KO muscles, running increased the mRNA content of PGC-1alpha and FOXO1 similarly. The alpha2-KO was associated with lower muscle adenosine 5'-triphosphate content, and the inosine monophosphate content increased substantially at the end of exercise only in alpha2-KO muscles. In addition, subcutaneous injection of 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR) increased the mRNA content of PGC-1alpha, HKII, FOXO1, PDK4, and UCP3, and alpha2-KO abolished the AICAR-induced increases in PGC-1alpha and HKII mRNA. In conclusion, KO of the alpha2- but not the alpha1-AMPK isoform markedly diminished AMPK activation during running. Nevertheless, exercise-induced activation of the investigated genes in mouse skeletal muscle was not impaired in alpha1- or alpha2-AMPK KO muscles. Although it cannot be ruled out that activation of the remaining alpha-isoform is sufficient to increase gene activation during exercise, the present data do not support an essential role of AMPK in regulating exercise-induced gene activation in skeletal muscle.
Jørgensen
Sebastian B
SB
Copenhagen Muscle Research Centre, Department of Human Physiology, Institute of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark. sbjorgensen@ifi.ku.dk
Wojtaszewski
Jørgen F P
JF
Viollet
Benoit
B
Andreelli
Fabrizio
F
Birk
Jesper B
JB
Hellsten
Ylva
Y
Schjerling
Peter
P
Vaulont
Sophie
S
Neufer
P Darrell
PD
Richter
Erik A
EA
Pilegaard
Henriette
H
D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase / Q000032:analysis; D000249:Adenosine Monophosphate / Q000032:analysis; D000255:Adenosine Triphosphate / Q000032:analysis; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D006003:Glycogen / Q000032:analysis; D006593:Hexokinase / Q000235:genetics; D007291:Inosine Monophosphate / Q000032:analysis; D007473:Ion Channels; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D024101:Mitochondrial Proteins; D009097:Multienzyme Complexes / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010805:Physical Conditioning, Animal; D011494:Protein Kinases / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D012265:Ribonucleotides / Q000494:pharmacology; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D000071247:Uncoupling Protein 3
D002352:Carrier Proteins; D007473:Ion Channels; D024101:Mitochondrial Proteins; D009097:Multienzyme Complexes; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D012333:RNA, Messenger; D012265:Ribonucleotides; D015534:Trans-Activators; D014157:Transcription Factors; C000604392:UCP3 protein, human; C000604393:Ucp3 protein, mouse; D000071247:Uncoupling Protein 3; D007291:Inosine Monophosphate; D000620:Aminoimidazole Carboxamide; D000249:Adenosine Monophosphate; D000255:Adenosine Triphosphate; D006003:Glycogen; D011494:Protein Kinases; C403287:pyruvate dehydrogenase kinase 4; D006593:Hexokinase; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; D000103:Acetyl-CoA Carboxylase; C031143:AICA ribonucleotide