Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/7/2007
Publication Date: 4/28/2007
Citation: Suryawan, A., Orellana, R.A., Jeyapalan, A.S., Nguyen, H.V., Fleming, J.R., Davis, T.A. 2007. The activation of nutrient signaling components leading to mRNA translation in skeletal muscle of neonatal pigs is developmentally regulated [abstract]. The Federation of American Societies for Experimental Biology Journal. 21(5):A714. Interpretive Summary:
Technical Abstract: 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 to eIF4G (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.