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J Biol Chem. 2013 Jan 11;288(2):1125-34. doi: 10.1074/jbc.M112.399949. Epub 2012 Dec 3.

Proteasome-dependent activation of mammalian target of rapamycin complex 1 (mTORC1) is essential for autophagy suppression and muscle remodeling following denervation.

Author information

1
Department of Physiology and Cell Biology, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.

Erratum in

  • J Biol Chem. 2013 May 10;288(19):13639.

Abstract

Drastic protein degradation occurs during muscle atrophy induced by denervation, fasting, immobility, and various systemic diseases. Although the ubiquitin-proteasome system is highly up-regulated in denervated muscles, the involvement of autophagy and protein synthesis has been controversial. Here, we report that autophagy is rather suppressed in denervated muscles even under autophagy-inducible starvation conditions. This is due to a constitutive activation of mammalian target of rapamycin complex 1 (mTORC1). We further reveal that denervation-induced mTORC1 activation is dependent on the proteasome, which is likely mediated by amino acids generated from proteasomal degradation. Protein synthesis and ribosome biogenesis are paradoxically increased in denervated muscles in an mTORC1-dependent manner, and mTORC1 activation plays an anabolic role against denervation-induced muscle atrophy. These results suggest that denervation induces not only muscle degradation but also adaptive muscle response in a proteasome- and mTORC1-dependent manner.

PMID:
23209294
PMCID:
PMC3542997
DOI:
10.1074/jbc.M112.399949
[Indexed for MEDLINE]
Free PMC Article

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