title: Reduced AMPK-ACC and mTOR signaling in muscle from older men, and effect of resistance exercise.
abstract: AMP-activated protein kinase (AMPK) is a key energy-sensitive enzyme that controls numerous metabolic and cellular processes. Mammalian target of rapamycin (mTOR) is another energy/nutrient-sensitive kinase that controls protein synthesis and cell growth. In this study we determined whether older versus younger men have alterations in the AMPK and mTOR pathways in skeletal muscle, and examined the effect of a long term resistance type exercise training program on these signaling intermediaries. Older men had decreased AMPKα2 activity and lower phosphorylation of AMPK and its downstream signaling substrate acetyl-CoA carboxylase (ACC). mTOR phosphylation also was reduced in muscle from older men. Exercise training increased AMPKα1 activity in older men, however, AMPKα2 activity, and the phosphorylation of AMPK, ACC and mTOR, were not affected. In conclusion, older men have alterations in the AMPK-ACC and mTOR pathways in muscle. In addition, prolonged resistance type exercise training induces an isoform-selective up regulation of AMPK activity.
authors.affiliation: Geriatric Research, Education and Clinical Center, Audie L. Murphy Veterans Hospital, 7400 Merton Minter Blvd, San Antonio, TX 78229, USA.
authors.forename: Mengyao
authors.initials: M
authors.lastname: Li
authors.forename: Lex B
authors.initials: LB
authors.lastname: Verdijk
authors.forename: Kei
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Brian
authors.initials: B
authors.lastname: Ely
authors.forename: Luc J C
authors.initials: LJ
authors.lastname: van Loon
authors.forename: Nicolas
authors.initials: N
authors.lastname: Musi
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D001835:Body Weight; D015444:Exercise; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D055070:Resistance Training; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D011494:Protein Kinases; C546842:MTOR protein, human; C526181:PRKAA2 protein, human; D058570:TOR Serine-Threonine Kinases; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; C526180:PRKAA1 protein, human; D000103:Acetyl-CoA Carboxylase