Role of AMP-activated protein kinase in the coordinated expression of genes controlling glucose and lipid metabolism in mouse white skeletal muscle.
OBJECTIVE
AMP-activated protein kinase (AMPK) regulates metabolic adaptations in skeletal muscle. The aim of this study was to investigate whether AMPK modulates the expression of skeletal muscle genes that have been implicated in lipid and glucose metabolism under fed or fasting conditions.


METHODS
Two genetically modified animal models were used: AMPK gamma3 subunit knockout mice (Prkag3(-/-)) and skeletal muscle-specific transgenic mice (Tg-Prkag3(225Q)) that express a mutant (R225Q) gamma3 subunit. Levels of mRNA transcripts of genes involved in lipid and glucose metabolism in white gastrocnemius muscles of these mice (under fed or 16-h fasting conditions) were assessed by quantitative real-time PCR.


RESULTS
Wild-type mice displayed a coordinated increase in the transcription of skeletal muscle genes encoding proteins involved in lipid/oxidative metabolism (lipoprotein lipase, fatty acid transporter, carnitine palmitoyl transferase-1 and citrate synthase) and glucose metabolism (glycogen synthase and lactate dehydrogenase) in response to fasting. In contrast, these fasting-induced responses were impaired in Prkag3(-/-) mice. The transcription of genes involved in lipid and oxidative metabolism was increased in the skeletal muscle of Tg-Prkag3(225Q) mice compared with that in wild-type mice. Moreover, the expression of the genes encoding hexokinase II and 6-phosphofrucktokinase was decreased in Tg-Prkag3(225Q) mice after fasting.


CONCLUSIONS
AMPK is involved in the coordinated transcription of genes critical for lipid and glucose metabolism in white glycolytic skeletal muscle.
Long
Y C
YC
Department of Surgical Sciences, Section for Integrative Physiology, Karolinska Institute, Stockholm, Sweden.
Barnes
B R
BR
Mahlapuu
M
M
Steiler
T L
TL
Martinsson
S
S
Leng
Y
Y
Wallberg-Henriksson
H
H
Andersson
L
L
Zierath
J R
JR
D055372:AMP-Activated Protein Kinases; D000105:Acetyl Coenzyme A / Q000378:metabolism; D000818:Animals; D018955:CD36 Antigens / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D007473:Ion Channels; D007527:Isoenzymes / Q000235:genetics; D007770:L-Lactate Dehydrogenase / Q000235:genetics; D050356:Lipid Metabolism / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D024101:Mitochondrial Proteins; D009097:Multienzyme Complexes / Q000235:genetics* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000502:physiology*; D009154:Mutation; D047495:PPAR gamma / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism; D000071247:Uncoupling Protein 3
D018955:CD36 Antigens; D002352:Carrier Proteins; D005230:Fatty Acids, Nonesterified; D007473:Ion Channels; D007527:Isoenzymes; D024101:Mitochondrial Proteins; D009097:Multienzyme Complexes; D047495:PPAR gamma; D014280:Triglycerides; D000071247:Uncoupling Protein 3; D000105:Acetyl Coenzyme A; D006003:Glycogen; D007770:L-Lactate Dehydrogenase; C409676:lactate dehydrogenase 2; D011494:Protein Kinases; C403287:pyruvate dehydrogenase kinase 4; C526221:Prkag3 protein, mouse; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; D005947:Glucose