Nutritional and contractile regulation of human skeletal muscle protein synthesis and mTORC1 signaling

J Appl Physiol (1985). 2009 Apr;106(4):1374-84. doi: 10.1152/japplphysiol.91397.2008. Epub 2009 Jan 15.

Abstract

In this review we discuss current findings in the human skeletal muscle literature describing the acute influence of nutrients (leucine-enriched essential amino acids in particular) and resistance exercise on muscle protein synthesis and mammalian target of rapamycin complex 1 (mTORC1) signaling. We show that essential amino acids and an acute bout of resistance exercise independently stimulate human skeletal muscle protein synthesis. It also appears that ingestion of essential amino acids following resistance exercise leads to an even larger increase in the rate of muscle protein synthesis compared with the independent effects of nutrients or muscle contraction. Until recently the cellular mechanisms responsible for controlling the rate of muscle protein synthesis in humans were unknown. In this review, we highlight new studies in humans that have clearly shown the mTORC1 signaling pathway is playing an important regulatory role in controlling muscle protein synthesis in response to nutrients and/or muscle contraction. We propose that essential amino acid ingestion shortly following a bout of resistance exercise is beneficial in promoting skeletal muscle growth and may be useful in counteracting muscle wasting in a variety of conditions such as aging, cancer cachexia, physical inactivity, and perhaps during rehabilitation following trauma or surgery.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Aging / physiology
  • Exercise / physiology
  • Gene Expression
  • Humans
  • Mechanistic Target of Rapamycin Complex 1
  • Multiprotein Complexes
  • Muscle Contraction / physiology
  • Muscle Proteins / biosynthesis*
  • Muscle, Skeletal / metabolism*
  • Muscle, Skeletal / physiology*
  • Nutritional Physiological Phenomena / physiology*
  • Protein Biosynthesis
  • Proteins
  • Signal Transduction / physiology*
  • TOR Serine-Threonine Kinases
  • Transcription Factors / physiology*

Substances

  • Multiprotein Complexes
  • Muscle Proteins
  • Proteins
  • Transcription Factors
  • TOR Serine-Threonine Kinases
  • Mechanistic Target of Rapamycin Complex 1