Nutrient signaling in the regulation of human muscle protein synthesis

• Published in: The FASEB journal 2007-04, Vol.21 (5), p.A713-A713
• Main Authors: Fujita, Satoshi, Dreyer, Hans C, Drummond, Micah J, Glynn, Erin L, Cadenas, Jerson G, Yoshizawa, Fumiaki, Volpi, Elena, Rasmussen, Blake B
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.21.5.A713-c

AMPK and mTOR are important energy and nutrient sensing and signaling proteins in muscle. AMPK activation decreases muscle protein synthesis (MPS) by inhibiting mTOR signaling. Essential amino acids and insulin stimulate mTOR signaling and MPS. We hypothesized that anabolic nutrients would be sensed by both AMPK and mTOR resulting in an acute and potent stimulation of MPS via enhanced translation initiation and elongation. We measured MPS and mTOR‐associated upstream and downstream signaling proteins in young subjects using stable isotopic and immunoblotting techniques. Following a 1st muscle biopsy from the vastus lateralis, subjects ingested a nutrient mixture (EAC) containing essential amino acids (0.35 grams/kg LM) and carbohydrate (0.5 grams/kg LM). Total caloric content was 186.9 ± 8 kcal. A 2nd biopsy was obtained 1 hr later. Ingestion of EAC significantly increased MPS, Akt/PKB, and mTOR phosphorylation (P