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The activation of nutrient signaling components leading to mRNA translation in skeletal muscle of neonatal pigs is developmentally regulated
Author(s) -
Suryawan Agus,
Orellana Renan A.,
Jeyapalan Asumthia S.,
Nguyen Hanh V.,
Fleming Jillian R.,
Davis Teresa A.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a714
Subject(s) - skeletal muscle , medicine , p70 s6 kinase 1 , endocrinology , phosphorylation , amino acid , pi3k/akt/mtor pathway , protein biosynthesis , insulin , translational regulation , translation (biology) , protein kinase b , biology , messenger rna , chemistry , signal transduction , biochemistry , gene
Insulin and amino acids (AA) can act independently to stimulate skeletal muscle protein synthesis in neonatal pigs. To elucidate the role of development in the AA‐induced activation of nutrient signaling components leading to translation in skeletal muscle, a balanced AA mixture was infused into fasted 6‐d ( n = 4) and 26‐d‐old pigs ( n = 6) to raise branched‐chain amino acids (BCAA) from 500 μmol/L (fasting level) to 1000 μmol/L BCAA (fed level) while insulin was maintained at fasting levels. AA increased the fractional rate of muscle protein synthesis (P<0.05) and the response decreased with development (P<0.05). AA did not induce the phosphorylation of PKB. AA increased the phosphorylation of mTOR, S6K1, and 4E‐BP1 and the response was higher in 6‐d compared to 26‐d‐old pigs (P<0.05). AA tended to reduce the binding of raptor to mTOR (P=0.09) in 6‐d‐old pigs. AA decreased the binding of 4E‐BP1 to eIF4E (P<0.05) and increased eIF4E binding toeIF4G (P<0.05), and these effects were greater in 6‐d than in 26‐d‐old pigs (P<0.05). Furthermore, neither AA nor age affected the phosphorylation of eEF2. Our results suggest that the activation of most nutrient signaling components in muscle is developmentally regulated and parallels the developmental decline in protein synthesis in skeletal muscle of neonatal pigs. NIH AR44474, USDA 58‐6250‐6‐001