Location: Children's Nutrition Research CenterTitle: Insulin signaling is a modulator of muscle growth Author
Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/13/2010
Publication Date: 7/13/2010
Citation: Davis, T.A., Suryawan, A., Orellana, R.A., Fiorotto, M. 2010. Insulin signaling is a modulator of muscle growth. Journal of Animal Science. 88(E-Suppl. 2):529. Interpretive Summary:
Technical Abstract: The growth rate of skeletal muscle during the neonatal period is higher than at any other stage of postnatal development and is driven by an elevated rate of protein synthesis. The high rate of muscle protein synthesis in neonatal mammals is in part due to a marked stimulation of protein synthesis after feeding. This response to feeding is, in part, due to an enhanced sensitivity to the postprandial rise in insulin. The effect of insulin on protein synthesis is most pronounced in skeletal muscle. The decline with age in the response of muscle protein synthesis to insulin parallels the developmental decline in the rate of muscle protein synthesis. The high rate of protein synthesis in neonatal muscle is in part due to an enhanced activation of the insulin signaling pathway. Thus, the postprandial rise in insulin activates in muscle the insulin receptor, insulin receptor substrate 1/2, phosphatidylinositol 3-kinase, phosphoinositide-dependent kinase 1, protein kinase B, mammalian target of rapamycin, ribosomal protein S6 kinase-1, eukaryotic initiation factor (eIF) 4E-binding protein 1, and eIF4E associated with eIF4G and these responses decrease with development. The reduced activation of negative regulators of insulin signaling also contributes to the high rate of neonatal muscle protein synthesis. These include protein tyrosine phosphatase 1B, phosphatase and tensin homolog deleted on chromosome 10, protein phosphatase 2A, tuberous sclerosis 2, and proline-rich Akt/PKB substrate 40 kDa. These studies demonstrate that the high rate of protein synthesis and rapid gain in skeletal muscle mass in neonatal pigs are in part modulated by changes in the activation of components in the insulin signaling pathway.