title: Regulation of protein synthesis by amino acids in muscle of neonates.
abstract: The marked increase in skeletal muscle mass during the neonatal period is largely due to a high rate of postprandial protein synthesis that is modulated by an enhanced sensitivity to insulin and amino acids. The amino acid signaling pathway leading to the stimulation of protein synthesis has not been fully elucidated. Among the amino acids, leucine is considered to be a principal anabolic agent that regulates protein synthesis. mTORC1, which controls protein synthesis, has been implicated as a target for leucine. Until recently, there have been few studies exploring the role of amino acids in enhancing muscle protein synthesis in vivo. In this review, we discuss amino acid-induced protein synthesis in muscle in the neonate, focusing on current knowledge of the role of amino acids in the activation of mTORC1 leading to mRNA translation. The role of the amino acid transporters, SNAT2, LAT1, and PAT, in the modulation of mTORC1 activation and the role of amino acids in the activation of putative regulators of mTORC1, i.e., raptor, Rheb, MAP4K3, Vps34, and Rag GTPases, are discussed.
authors.affiliation: United States Department Of Agriculture/Agriculture Research Service, Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Agus
authors.initials: A
authors.lastname: Suryawan
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Davis
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology; D026924:Amino Acid Transport System A / Q000502:physiology; D026905:Amino Acid Transport Systems / Q000502:physiology; D000596:Amino Acids / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D058546:Class III Phosphatidylinositol 3-Kinases / Q000502:physiology; D006801:Humans; D007231:Infant, Newborn; D027283:Large Neutral Amino Acid-Transporter 1 / Q000502:physiology; D007930:Leucine / Q000494:pharmacology; D000076222:Mechanistic Target of Rapamycin Complex 1; D020559:Monomeric GTP-Binding Proteins / Q000502:physiology; D046912:Multiprotein Complexes; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D009479:Neuropeptides / Q000502:physiology; D014176:Protein Biosynthesis / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011506:Proteins / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D000076205:Ras Homolog Enriched in Brain Protein; D000076223:Regulatory-Associated Protein of mTOR; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013552:Swine; D027981:Symporters / Q000502:physiology; D058570:TOR Serine-Threonine Kinases; D020663:ras Guanine Nucleotide Exchange Factors / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D026924:Amino Acid Transport System A; D026905:Amino Acid Transport Systems; D000596:Amino Acids; D027283:Large Neutral Amino Acid-Transporter 1; D046912:Multiprotein Complexes; D009124:Muscle Proteins; D009479:Neuropeptides; D011506:Proteins; C490211:RHEB protein, human; D012333:RNA, Messenger; C463659:RPTOR protein, human; D000076205:Ras Homolog Enriched in Brain Protein; D000076223:Regulatory-Associated Protein of mTOR; C475905:SLC36A1 protein, human; C498797:SLC38A2 protein, human; D027981:Symporters; D020663:ras Guanine Nucleotide Exchange Factors; D058546:Class III Phosphatidylinositol 3-Kinases; C543044:MAP4K3 protein, human; D000076222:Mechanistic Target of Rapamycin Complex 1; D017346:Protein Serine-Threonine Kinases; D058570:TOR Serine-Threonine Kinases; D020559:Monomeric GTP-Binding Proteins; D007930:Leucine