Increases in skeletal muscle ATGL and its inhibitor G0S2 following 8 weeks of endurance training in metabolically different rat skeletal muscles.
Adipose triglyceride lipase (ATGL) catalyzes the rate-limiting removal of the first fatty acid from a triglyceride. ATGL is activated by comparative gene identification-58 and inhibited by G(0)/G(1) switch gene-2 protein (G0S2). Research in other tissues and cell culture indicates that inhibition is dependent on relative G0S2-to-ATGL protein content. G0S2 may also have several roles within mitochondria; however, this has yet to be observed in skeletal muscle. The purpose of this study was to determine if muscle G0S2 relative to ATGL content would decrease to facilitate intramuscular lipolysis following endurance training. Male Sprague-Dawley rats (n = 10; age 51-53 days old) were progressively treadmill trained at a 10% incline for 8 wk ending with 25 m/min for 1 h compared with control. Sciatic nerve stimulation for hind-limb muscle contraction (and lipolysis) was administered for 30 min to one leg, leaving the opposing leg as a resting control. Soleus (SOL), red gastrocnemius (RG), and white gastrocnemius were excised from both legs following stimulation or control. ATGL protein increased in all trained muscles. Unexpectedly, G0S2 protein was greater in the trained SOL and RG. In RG-isolated mitochondria, G0S2 also increased with training, yet mitochondrial G0S2 content was unaltered with acute contraction; therefore, any role of G0S2 in the mitochondria does not appear to be acutely mediated by content alone. In summary, G0S2 increased with training in oxidative muscles and mitochondria but not following acute contraction, suggesting that inhibition is not through relative G0S2-to-ATGL content but through more complicated intracellular mechanisms.
Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada.
Patrick C
PC
Turnbull
Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada.
Amanda B
AB
Longo
Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada.
Sofhia V
SV
Ramos
Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada.
Brian D
BD
Roy
Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada.
Wendy E
WE
Ward
Department of Kinesiology, Centre for Bone and Muscle Health, Brock University, St. Catharines, Ontario, Canada sandra.peters@brocku.ca.
Sandra J
SJ
Peters
D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D004558:Electric Stimulation; D008049:Lipase / Q000378:metabolism*; D008066:Lipolysis; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000201:enzymology* / Q000294:innervation; D010084:Oxidation-Reduction; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000502:physiology; D013997:Time Factors; D014280:Triglycerides / Q000378:metabolism; D015854:Up-Regulation; D000217:Acyltransferases
D018797:Cell Cycle Proteins; D008049:Lipase; D014280:Triglycerides; C586945:G0S2 protein, rat; C571275:PNPLA2 protein, rat; D000217:Acyltransferases
CGI-58; G0S2; adipose triglyceride lipase; endurance training; muscle lipolysis; stimulated contraction