Abstract
Autophagy allows cell survival during starvation through the bulk degradation of proteins and organelles by lysosomal enzymes. However, the mechanisms responsible for the induction and regulation of the autophagy program are poorly understood. Here we show that the FoxO3 transcription factor, which plays a critical role in muscle atrophy, is necessary and sufficient for the induction of autophagy in skeletal muscle in vivo. Akt/PKB activation blocks FoxO3 activation and autophagy, and this effect is not prevented by rapamycin. FoxO3 controls the transcription of autophagy-related genes, including LC3 and Bnip3, and Bnip3 appears to mediate the effect of FoxO3 on autophagy. This effect is not prevented by proteasome inhibitors. Thus, FoxO3 controls the two major systems of protein breakdown in skeletal muscle, the ubiquitin-proteasomal and autophagic/lysosomal pathways, independently. These findings point to FoxO3 and Bnip3 as potential therapeutic targets in muscle wasting disorders and other degenerative and neoplastic diseases in which autophagy is involved.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Autophagy / genetics
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Autophagy / physiology*
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Forkhead Box Protein O3
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Forkhead Transcription Factors / antagonists & inhibitors
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Forkhead Transcription Factors / genetics
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Forkhead Transcription Factors / metabolism*
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Gene Expression Regulation
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Lysosomes / metabolism
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Mice
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Mice, Transgenic
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Microtubule-Associated Proteins / genetics
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Microtubule-Associated Proteins / metabolism
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Mitochondrial Proteins / genetics
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Mitochondrial Proteins / metabolism
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Models, Biological
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Muscle, Skeletal / cytology*
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Muscle, Skeletal / metabolism*
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Muscular Atrophy / genetics
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Muscular Atrophy / metabolism
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Muscular Atrophy / pathology
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Proteasome Endopeptidase Complex / metabolism
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Protein Kinases / genetics
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Protein Kinases / metabolism
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Proto-Oncogene Proteins c-akt / genetics
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Proto-Oncogene Proteins c-akt / metabolism
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RNA Interference
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TOR Serine-Threonine Kinases
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Ubiquitin / metabolism
Substances
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BNip3 protein, mouse
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Forkhead Box Protein O3
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Forkhead Transcription Factors
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FoxO3 protein, mouse
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Map1lc3b protein, mouse
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Membrane Proteins
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Microtubule-Associated Proteins
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Mitochondrial Proteins
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Ubiquitin
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Protein Kinases
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mTOR protein, mouse
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Proto-Oncogene Proteins c-akt
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TOR Serine-Threonine Kinases
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Proteasome Endopeptidase Complex