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BMC Physiology
Published in: BMC Physiology 1/2011

Open Access 01-12-2011 | Research article

The actions of exogenous leucine on mTOR signalling and amino acid transporters in human myotubes

Authors: Petra Gran, David Cameron-Smith

Published in: BMC Physiology | Issue 1/2011

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Abstract

Background

The branched-chain amino acid (BCAA) leucine has been identified to be a key regulator of skeletal muscle anabolism. Activation of anabolic signalling occurs via the mammalian target of rapamycin (mTOR) through an undefined mechanism. System A and L solute carriers transport essential amino acids across plasma membranes; however it remains unknown whether an exogenous supply of leucine regulates their gene expression. The aim of the present study was to investigate the effects of acute and chronic leucine stimulation of anabolic signalling and specific amino acid transporters, using cultured primary human skeletal muscle cells.

Results

Human myotubes were treated with leucine, insulin or co-treated with leucine and insulin for 30 min, 3 h or 24 h. Activation of mTOR signalling kinases were examined, together with putative nutrient sensor human vacuolar protein sorting 34 (hVps34) and gene expression of selected amino acid transporters. Phosphorylation of mTOR and p70S6K was transiently increased following leucine exposure, independently to insulin. hVps34 protein expression was also significantly increased. However, genes encoding amino acid transporters were differentially regulated by insulin and not leucine.

Conclusions

mTOR signalling is transiently activated by leucine within human myotubes independently of insulin stimulation. While this occurred in the absence of changes in gene expression of amino acid transporters, protein expression of hVps34 increased.
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Metadata
Title
The actions of exogenous leucine on mTOR signalling and amino acid transporters in human myotubes
Authors
Petra Gran
David Cameron-Smith
Publication date
01-12-2011
Publisher
BioMed Central
Published in
BMC Physiology / Issue 1/2011
Electronic ISSN: 1472-6793
DOI
https://doi.org/10.1186/1472-6793-11-10

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