Exercise-associated differences in an array of proteins involved in signal transduction and glucose transport.
Vastus lateralis muscle biopsies were obtained from endurance-trained (running approximately 50 km/wk) and untrained (no regular physical exercise) men, and the expression of an array of insulin-signaling intermediates was determined. Expression of insulin receptor and insulin receptor substrate-1 and -2 was decreased 44% (P < 0.05), 57% (P < 0.001), and 77% (P < 0.001), respectively, in trained vs. untrained muscle. The downstream signaling target, Akt kinase, was not altered in trained subjects. Components of the mitogenic signaling cascade were also assessed. Extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase expression was 190% greater (P < 0.05), whereas p38 mitogen-activated protein kinase expression was 32% lower (P < 0.05), in trained vs. untrained muscle. GLUT-4 protein expression was twofold higher (P < 0.05), and the GLUT-4 vesicle-associated protein, the insulin-regulated aminopeptidase, was increased 4.7-fold (P < 0. 05) in trained muscle. In conclusion, the expression of proteins involved in signal transduction is altered in skeletal muscle from well-trained athletes. Downregulation of early components of the insulin-signaling cascade may occur in response to increased insulin sensitivity associated with endurance training.
Yu
M
M
Department of Clinical Physiology, Karolinska Hospital, SE-171 76 Stockholm, Sweden.
Blomstrand
E
E
Chibalin
A V
AV
Wallberg-Henriksson
H
H
Zierath
J R
JR
Krook
A
A
D000328:Adult; D000626:Aminopeptidases / Q000378:metabolism; D002950:Citrate (si)-Synthase / Q000378:metabolism; D010122:Cystinyl Aminopeptidase; D015444:Exercise / Q000502:physiology*; D051275:Glucose Transporter Type 4; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010806:Physical Education and Training; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011972:Receptor, Insulin / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases
D051275:Glucose Transporter Type 4; C526292:IRS1 protein, human; C526297:IRS2 protein, human; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; C495692:SLC2A4 protein, human; D002950:Citrate (si)-Synthase; D011972:Receptor, Insulin; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D000626:Aminopeptidases; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase