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Vol. 64 No. 10: Issue 10

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Leucine can modulate the expression of proteins related to protein degradation signalling under mTOR inhibition in C2C12 cells

https://doi.org/10.14715/cmb/2018.64.10.12
Bianca Cristine Favero-Santos
Laboratory of Nutrition and Cancer, Department of Structural and Functional Biology, Biology Institute, University of Campinas, Zip Code 13083862, Campinas, Sao Paulo, Brazil
Maria Cristina Cintra Gomes-Marcondes
Laboratory of Nutrition and Cancer, Department of Structural and Functional Biology, Biology Institute, University of Campinas, Zip Code 13083862, Campinas, Sao Paulo, Brazil
http://orcid.org/0000-0002-1713-756X

Corresponding Author(s) : Maria Cristina Cintra Gomes-Marcondes

cintgoma@unicamp.br

Cellular and Molecular Biology, Vol. 64 No. 10: Issue 10

Abstract

Many metabolic syndromes lead to energetic disturbs which ends to an intense catabolic state. The branched-chain amino acid leucine shows very positive effects on muscle protein metabolism. However, it is still not clear how leucine acts improving the protein turnover. This study aimed to evaluate in vitro the effects of leucine supplementation in minimising the signalling pathway of protein degradation when mTOR was inhibited. Our studies were conducted in murine C2C12 myotubes exposed to 2mM leucine or 2mM isoleucine in control situation and compared to the inhibition of mTOR by rapamycin. Then, the expression of proteins related to protein synthesis and degradation signalling pathway was obtained by Western Blot. At this concentration, the leucine was sufficient to maintain the expression of proteins evaluated as in control situation. However, when the cells were exposed to rapamycin (80nM), leucine inhibited the expression of SMAD and FoxO3a, showing that leucine was able to modulate the degradation pathway when protein synthesis is compromised. Furthermore, leucine had no effect in modifying the expression of subunits of ubiquitin-proteasome system, showing that leucine had no direct effect in ubiquitin-proteasome system, but acted leading to the phosphorylation of SMAD and FoxO3, which inhibited the activity of transcriptional of these proteins. No similar results were observed in cells exposed to isoleucine under the same experimental protocol, likely showing that leucine has specific action over another branched-chain amino acids. In conclusion, the present study shows that leucine can modulate degradation pathways even under inhibition of mTOR by rapamycin.

Keywords

Myotubes C2C12 Cell culture Leucine Protein metabolism.
Favero-Santos, B. C., & Gomes-Marcondes, M. C. C. (2018). Leucine can modulate the expression of proteins related to protein degradation signalling under mTOR inhibition in C2C12 cells. Cellular and Molecular Biology, 64(10), 73–78. https://doi.org/10.14715/cmb/2018.64.10.12
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