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Identification and Small Molecule Inhibition of an Activating Transcription Factor 4 (ATF4)-dependent Pathway to Age-related Skeletal Muscle Weakness and Atrophy.

ABSTRACT: Aging reduces skeletal muscle mass and strength, but the underlying molecular mechanisms remain elusive. Here, we used mouse models to investigate molecular mechanisms of age-related skeletal muscle weakness and atrophy as well as new potential interventions for these conditions. We identified two small molecules that significantly reduce age-related deficits in skeletal muscle strength, quality, and mass: ursolic acid (a pentacyclic triterpenoid found in apples) and tomatidine (a steroidal alkaloid derived from green tomatoes). Because small molecule inhibitors can sometimes provide mechanistic insight into disease processes, we used ursolic acid and tomatidine to investigate the pathogenesis of age-related muscle weakness and atrophy. We found that ursolic acid and tomatidine generate hundreds of small positive and negative changes in mRNA levels in aged skeletal muscle, and the mRNA expression signatures of the two compounds are remarkably similar. Interestingly, a subset of the mRNAs repressed by ursolic acid and tomatidine in aged muscle are positively regulated by activating transcription factor 4 (ATF4). Based on this finding, we investigated ATF4 as a potential mediator of age-related muscle weakness and atrophy. We found that a targeted reduction in skeletal muscle ATF4 expression reduces age-related deficits in skeletal muscle strength, quality, and mass, similar to ursolic acid and tomatidine. These results elucidate ATF4 as a critical mediator of age-related muscle weakness and atrophy. In addition, these results identify ursolic acid and tomatidine as potential agents and/or lead compounds for reducing ATF4 activity, weakness, and atrophy in aged skeletal muscle.

SUBMITTER: Ebert SM

PROVIDER: S-EPMC4646196 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature

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Identification and Small Molecule Inhibition of an Activating Transcription Factor 4 (ATF4)-dependent Pathway to Age-related Skeletal Muscle Weakness and Atrophy.

Ebert Scott M SM Dyle Michael C MC Bullard Steven A SA Dierdorff Jason M JM Murry Daryl J DJ Fox Daniel K DK Bongers Kale S KS Lira Vitor A VA Meyerholz David K DK Talley John J JJ Adams Christopher M CM

The Journal of biological chemistry 20150903 42

Aging reduces skeletal muscle mass and strength, but the underlying molecular mechanisms remain elusive. Here, we used mouse models to investigate molecular mechanisms of age-related skeletal muscle weakness and atrophy as well as new potential interventions for these conditions. We identified two small molecules that significantly reduce age-related deficits in skeletal muscle strength, quality, and mass: ursolic acid (a pentacyclic triterpenoid found in apples) and tomatidine (a steroidal alka ...[more]

PMID: 26338703

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Project description:Age-related skeletal muscle atrophy is a debilitating condition that has significant negative impacts on health and quality of life. Despite broad clinical impact, the molecular basis of age-related skeletal muscle atrophy is not well understood. Here, we determined protein turnover rates in skeletal muscle of 22-month-old control mice and 22-month-old muscle-specific ATF4 knockout (ATF4 mKO) mice, which are partially resistant to age-related muscle atrophy. All samples were analyzed by DDA TripleTOF 6600 mass spectrometer for downstream analysis of protein turnover. Quantitative MS1 peak areas were extracted from DDA raw files in the Skyline-Daily software platform. ProteinPilot search results were imported into the Skyline software to build a spectral library, followed by import of raw MS files for extraction of chromatographic peak areas. A custom skyline report containing all peptide and protein characteristics, annotations, and quantitative information including isotopologue peak areas was exported and used for downstream analysis and calculation of protein turnover rates in R using in-house R scripts (TurnoveR tool). Precursor-pool corrected protein turnover rates were calculated using the same approach employed in previous studies using the Topograph software platform. For calculation of protein abundance changes, DIA acquisitions from six samples (3 ATF4 KO and 3 WT samples) were quantitatively processed using Spectronaut v14. Analysis of protein turnover indicates that most proteins with altered turnover rates in ATF4 mKO muscles have decreased half-lives and are components of the mitochondrion. These proteins include subunits of the ATP Synthase (Atp5b, Atp5o), Ubiquinol-Cytochrome C Reductase (Uqcrc1, Uqcrh) and Cytochrome C Oxidase (Cox6b1) complexes, among others. These findings implicate increased rates of mitochondrial protein turnover as a mechanism that underlies, at least in part, the protection from age-induced muscle atrophy in ATF4 mKO mice.

Dataset Information

Identification and Small Molecule Inhibition of an Activating Transcription Factor 4 (ATF4)-dependent Pathway to Age-related Skeletal Muscle Weakness and Atrophy.

Publications

Identification and Small Molecule Inhibition of an Activating Transcription Factor 4 (ATF4)-dependent Pathway to Age-related Skeletal Muscle Weakness and Atrophy.

Similar Datasets

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