The role of nutrition in stimulating muscle protein accretion at the molecular level.
Nutrients act both directly and indirectly to modulate muscle protein accretion through changes in protein synthesis and degradation. For example, glucose, amino acids and fatty acids can all be metabolized to produce energy in the form of ATP that can be utilized for protein synthesis. In addition, amino acids are used directly for the synthesis of new proteins. Nutrients also regulate protein synthesis through activation of a signalling pathway involving the protein kinase, mTOR [mammalian TOR (target of rapamycin)]. Together with several regulatory proteins, mTOR forms a complex referred to as TORC1 (TOR complex 1). Because of its central role in controlling cell growth, TORC1 is an integral component of the mechanism through which nutrients modulate protein synthesis. Herein, the mechanism(s) through which nutrients, and in particular amino acids, regulate signalling through TORC1 will be discussed. In addition, downstream effectors of TORC1 action on mRNA translation will be briefly presented. Finally, a previously unrecognized effector of TORC1 signalling in regulating protein synthesis will be described.
Kimball
S R
SR
Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, U.S.A. skimball@psu.edu
D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D004032:Diet; D020717:Eukaryotic Initiation Factor-2B / Q000235:genetics; D006801:Humans; D009124:Muscle Proteins / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism
D000596:Amino Acids; C500984:CRTC1 protein, human; D020717:Eukaryotic Initiation Factor-2B; D009124:Muscle Proteins; D012333:RNA, Messenger; D014157:Transcription Factors