The effect of exercise and insulin on AS160 phosphorylation and 14-3-3 binding capacity in human skeletal muscle.
AS160 is an Akt substrate of 160 kDa implicated in the regulation of both insulin- and contraction-mediated GLUT4 translocation and glucose uptake. The effects of aerobic exercise and subsequent insulin stimulation on AS160 phosphorylation and the binding capacity of 14-3-3, a novel protein involved in the dissociation of AS160 from GLUT4 vesicles, in human skeletal muscle are unknown. Hyperinsulinemic-euglycemic clamps were performed on seven men at rest and immediately and 3 h after a single bout of cycling exercise. Skeletal muscle biopsies were taken before and after the clamps. The insulin sensitivity index calculated during the final 30 min of the clamp was 8.0 +/- 0.8, 9.1 +/- 0.5, and 9.2 +/- 0.8 for the rest, postexercise, and 3-h postexercise trials, respectively. AS160 phosphorylation increased immediately after exercise and remained elevated 3 h after exercise. In contrast, the 14-3-3 binding capacity of AS160 and phosphorylation of Akt and AMP-activated protein kinase were only increased immediately after exercise. Insulin increased AS160 phosphorylation and 14-3-3 binding capacity and insulin receptor substrate-1 and Akt phosphorylation, but the response to insulin was not enhanced by prior exercise. In conclusion, the 14-3-3 binding capacity of AS160 is increased immediately after acute exercise in human skeletal muscle, but this is not maintained 3 h after exercise completion despite sustained AS160 phosphorylation. Insulin increases AS160 phosphorylation and 14-3-3 binding capacity, but prior exercise does not appear to enhance the response to insulin.
Howlett
Kirsten F
KF
School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria 3125, Australia. kirsten.howlett@deakin.edu.au
Mathews
Alicia
A
Garnham
Andrew
A
Sakamoto
Kei
K
D048948:14-3-3 Proteins / Q000378:metabolism*; D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000328:Adult; D015153:Blotting, Western; D015444:Exercise / Q000502:physiology*; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D015309:Glucose Clamp Technique; D051275:Glucose Transporter Type 4 / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D047468:Immunoprecipitation; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D008297:Male; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D051058:Oncogene Protein v-akt / Q000096:biosynthesis; D010766:Phosphorylation; D011485:Protein Binding; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D048948:14-3-3 Proteins; D048868:Adaptor Proteins, Signal Transducing; D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D009124:Muscle Proteins; C495692:SLC2A4 protein, human; C518767:TBC1D4 protein, human; D051058:Oncogene Protein v-akt; D000103:Acetyl-CoA Carboxylase