title: Differential effects of exercise on insulin-signaling gene expression in human skeletal muscle.
abstract: Skeletal muscle insulin sensitivity is enhanced after acute exercise and short-term endurance training. We investigated the impact of exercise on the gene expression of key insulin-signaling proteins in humans. Seven untrained subjects (4 women and 3 men) completed 9 days of cycling at 63 +/- 2% of peak O(2) uptake for 60 min/day. Muscle biopsies were taken before, immediately after, and 3 h after the exercise bouts (on days 1 and 9). The gene expression of insulin receptor substrate-2 and the p85 alpha subunit of phosphatidylinositol 3-kinase was significantly higher 3 h after a single exercise bout, although short-term training ameliorated this effect. Gene expression of insulin receptor and insulin receptor substrate-1 was not significantly altered at any time point. These results suggest that exercise may have a transitory impact on the expression of insulin receptor substrate-2 and phosphatidylinositol 3-kinase; however, the predominant actions of exercise on insulin sensitivity appear not to reside in the transcriptional activation of the genes encoding major insulin-signaling proteins.
authors.affiliation: School of Health Sciences, Deakin University, Burwood, Victoria 3125, Australia.
authors.forename: G D
authors.initials: GD
authors.lastname: Wadley
authors.forename: R J
authors.initials: RJ
authors.lastname: Tunstall
authors.forename: A
authors.initials: A
authors.lastname: Sanigorski
authors.forename: G R
authors.initials: GR
authors.lastname: Collier
authors.forename: M
authors.initials: M
authors.lastname: Hargreaves
authors.forename: D
authors.initials: D
authors.lastname: Cameron-Smith
mesh_terms: D015444:Exercise; D005080:Exercise Test; D005260:Female; D006801:Humans; D007328:Insulin / Q000502:physiology*; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D011972:Receptor, Insulin / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic
chemical_list: C526292:IRS1 protein, human; C526297:IRS2 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D019869:Phosphatidylinositol 3-Kinases; D011972:Receptor, Insulin