Project description:Autophagy is a critical process in the regulation of muscle mass, function and integrity. The molecular mechanisms regulating autophagy are complex and still partly understood. Here, we identify and characterize a novel FoxO-dependent gene, d230025d16rik which we named Mytho (Macroautophagy and YouTH Optimizer), as a regulator of autophagy and skeletal muscle integrity in vivo. Mytho is significantly up-regulated in various mouse models of skeletal muscle atrophy. Short term depletion of MYTHO in mice attenuates muscle atrophy caused by fasting, denervation, cancer cachexia and sepsis. While MYTHO overexpression is sufficient to trigger muscle atrophy, MYTHO knockdown results in a progressive increase in muscle mass associated with a sustained activation of the mTORC1 signaling pathway. Prolonged MYTHO knockdown is associated with severe myopathic features, including impaired autophagy, muscle weakness, myofiber degeneration, and extensive ultrastructural defects, such as accumulation of autophagic vacuoles and tubular aggregates. Inhibition of the mTORC1 signaling pathway in mice using rapamycin treatment attenuates the myopathic phenotype triggered by MYTHO knockdown. Skeletal muscles from human patients diagnosed with myotonic dystrophy type 1 (DM1) display reduced Mytho expression, activation of the mTORC1 signaling pathway and impaired autophagy, raising the possibility that low Mytho expression might contribute to the progression of the disease. We conclude that MYTHO is a key regulator of muscle autophagy and integrity.
Project description:MYTHO: a novel regulator of skeletal muscle autophagy and integrity mRNA expression data for the mouse muscle (n=4 per group) were obtained using Affymetrix Mouse Clariom S Assay (Affymetrix, Santa Carla, CA) according to the manufacturer’s recommendations.
Project description:Autophagy is a critical process in the regulation of muscle mass, function and integrity. The molecular mechanisms regulating autophagy are complex and still partly understood. Here, we identify and characterize a novel FoxO-dependent gene, d230025d16rik which we named Mytho (Macroautophagy and YouTH Optimizer), as a regulator of autophagy and skeletal muscle integrity in vivo. Mytho is significantly up-regulated in various mouse models of skeletal muscle atrophy. Short term depletion of MYTHO in mice attenuates muscle atrophy caused by fasting, denervation, cancer cachexia and sepsis. While MYTHO overexpression is sufficient to trigger muscle atrophy, MYTHO knockdown results in a progressive increase in muscle mass associated with a sustained activation of the mTORC1 signaling pathway. Prolonged MYTHO knockdown is associated with severe myopathic features, including impaired autophagy, muscle weakness, myofiber degeneration, and extensive ultrastructural defects, such as accumulation of autophagic vacuoles and tubular aggregates. Inhibition of the mTORC1 signaling pathway in mice using rapamycin treatment attenuates the myopathic phenotype triggered by MYTHO knockdown. Skeletal muscles from human patients diagnosed with myotonic dystrophy type 1 (DM1) display reduced Mytho expression, activation of the mTORC1 signaling pathway and impaired autophagy, raising the possibility that low Mytho expression might contribute to the progression of the disease. We conclude that MYTHO is a key regulator of muscle autophagy and integrity.
Project description:Short-term MYTHO knockdown (KD) mRNA expression data for the mouse muscle (n=4 per group) were obtained using Affymetrix Mouse Clariom S Assay (Affymetrix, Santa Carla, CA) according to the manufacturer’s recommendations.
Project description:Metabolic rewiring is a well-established feature of muscle cells and a hallmark of cancer. In isocitrate dehydrogenase 1 and 2 mutant tumors, increased production of the oncometabolite D-2-hydroxyglutarate (D2-HG) is associated with myopathy. The connection between metabolic changes and proteomic remodeling in skeletal muscle remains poorly understood. We demonstrate that D2-HG impairs NAD+ redox homeostasis in myocytes, causing activation of autophagy via de-acetylation of microtubule-associated protein 1 light chain 3-II (LC3-II) by the nuclear deacetylase Sirt1. We integrated multi-omics data from mice treated with D2-HG and demonstrate that autophagy activation leads to skeletal muscle atrophy and sex-dependent metabolic and proteomic remodeling. We also characterized protein and metabolite interactions linking energy-substrate metabolism with chromatin organization and autophagy regulation. Collectively, our multi-omics approach exposes mechanisms by which the oncometabolite D2-HG induces metabolic and proteomic remodeling in skeletal muscle, and provides a conceptual framework for identifying potential therapeutic targets in cachexia.
Project description:The intestinal epithelium is continuously renewed by a pool of intestinal stem cells expressing Lgr5. We show that deletion of the key autophagy gene Atg7 affects the survival of Lgr5+ intestinal stem cells. Mechanistically, this involves defective DNA repair, oxidative stress, and altered interactions with the microbiota. This study highlights the importance of autophagy in maintaining the integrity of intestinal stem cells.