Resistance exercise decreases eIF2Bepsilon phosphorylation and potentiates the feeding-induced stimulation of p70S6K1 and rpS6 in young men.
We investigated the effect of resistance exercise and feeding on the activation of signaling proteins involved in translation initiation. Nine young men (23.7+/-0.41 yr; BMI=25.5+/-1.0 kg/m2; means+/-SE) were tested twice after they performed a strenuous bout of unilateral resistance exercise, such that their contralateral leg acted as a nonexercised comparator, in either the fasted and fed [1,000 kJ, each 90 min (3 doses): 10 g protein, 41 g carbohydrate, 4 g fat] states. Muscle biopsies were obtained 6 h postexercise from both legs, resulting in four experimental conditions: rest-fasted, rest-fed, exercise-fasted, and exercise-fed. Feeding increased PKB/Akt (Ser473) phosphorylation (P<0.05), while exercise increased the phosphorylation of Akt and the downstream 70 kDa S6 protein kinase (p70S6K1, Thr389) and ribosomal protein S6 (rpS6, Ser235/236, Ser240/244; all P<0.05). The combination of resistance exercise and feeding increased the phosphorylation of p70S6K1 (Thr389) and rpS6 (Ser240/244) above exercise alone (P<0.05). Exercise also reduced phosphorylation of the catalytic epsilon subunit of eukaryotic initiation factor 2B (eIF2Bepsilon, Ser540; P<0.05). Mammalian target of rapamycin (mTOR, Ser2448), glycogen synthase kinase-3beta (GSK-3beta, Ser9), and focal adhesion kinase (FAK, Tyr576/577) phosphorylation were unaffected by either feeding or resistance exercise (all P>0.14). In summary, feeding resulted in phosphorylation of Akt, while resistance exercise stimulated phosphorylation of Akt, p70S6K1, rpS6, and dephosphorylation eIF2Bepsilon with a synergistic effect of feeding and exercise on p70(S6K1) and its downstream target rpS6. We conclude that resistance exercise potentiates the effect of feeding on the phosphorylation and presumably activation of critical proteins involved in the regulation of muscle protein synthesis in young men.
Glover
Elisa I
EI
Department of Kinesiology, Exercise Metabolism Research Group, McMaster University, 1280 Main St. West, Hamilton, ON, Canada L8S 4K1.
Oates
Bryan R
BR
Tang
Jason E
JE
Moore
Daniel R
DR
Tarnopolsky
Mark A
MA
Phillips
Stuart M
SM
D000328:Adult; D000596:Amino Acids / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism; D004435:Eating; D020717:Eukaryotic Initiation Factor-2B / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005215:Fasting / Q000097:blood; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D009119:Muscle Contraction; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000235:genetics; D018482:Muscle, Skeletal / Q000201:enzymology*; D010766:Phosphorylation; D019518:Postprandial Period; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D038601:Ribosomal Protein S6 / Q000378:metabolism*; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases; D013997:Time Factors; D014891:Weight Lifting
D000596:Amino Acids; D001786:Blood Glucose; D020717:Eukaryotic Initiation Factor-2B; D007328:Insulin; D009124:Muscle Proteins; D038601:Ribosomal Protein S6; D011494:Protein Kinases; C546842:MTOR protein, human; D051416:Focal Adhesion Protein-Tyrosine Kinases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; C448901:ribosomal protein S6 kinase, 70kD, polypeptide 1; D038362:Glycogen Synthase Kinase 3