title: Short- and Long-Term Hindlimb Immobilization and Reloading: Profile of Epigenetic Events in Gastrocnemius.
abstract: Skeletal muscle dysfunction and atrophy are characteristic features accompanying chronic conditions. Epigenetic events regulate muscle mass and function maintenance. We hypothesized that the pattern of epigenetic events (muscle-enriched microRNAs and histone acetylation) and acetylation of transcription factors known to signal muscle wasting may differ between early- and late-time points in skeletal muscles of mice exposed to hindlimb immobilization (I) and recovery following I. Body and muscle weights, grip strength, muscle-enriched microRNAs, histone deacetylases (HDACs), acetylation of proteins, histones, and transcription factors (TF), myogenic TF factors, and muscle phenotype were assessed in gastrocnemius of mice exposed to periods (1, 2, 3, 7, 15, and 30 days, I groups) of hindlimb immobilization, and in those exposed to reloading for different periods of time (1, 3, 7, 15, and 30 days, R groups) following 7-day immobilization. Compared to non-immobilized controls, muscle weight, limb strength, microRNAs, especially miR-486, SIRT1 levels, and slow- and fast-twitch cross-sectional areas were decreased in mice of I groups, whereas Pax7 and acetylated FoxO1 and FoxO3 levels were increased. Muscle reloading following splint removal improved muscle mass loss, strength, and fiber atrophy, by increasing microRNAs, particularly miR-486, and SIRT1 content, while decreasing acetylated FoxO1 and FoxO3 levels. In this mouse model of disuse muscle atrophy, muscle-enriched microRNAs, especially miR-486, through Pax7 regulation delayed muscle cell differentiation following unloading of gastrocnemius muscle. Acetylation of FoxO1 and 3 seemed to drive muscle mass loss and atrophy, while deacetylation of these factors through SIRT1 would enable the muscle fibers to regenerate. J. Cell. Physiol. 232: 1415-1427, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Pulmonology Department-Muscle Wasting and Cachexia in Chronic Respiratory Diseases and Lung Cancer Research group, IMIM-Hospital del Mar, Parc de Salut Mar, Health and Experimental Sciences Department (CEXS), Universitat Pompeu Fabra (UPF), Barcelona, Spain.|Centro de Investigación en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III (ISCIII), Barcelona, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Chacon-Cabrera
authors.affiliation: Pulmonology Department-Muscle Wasting and Cachexia in Chronic Respiratory Diseases and Lung Cancer Research group, IMIM-Hospital del Mar, Parc de Salut Mar, Health and Experimental Sciences Department (CEXS), Universitat Pompeu Fabra (UPF), Barcelona, Spain.|Centro de Investigación en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III (ISCIII), Barcelona, Spain.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Gea
authors.affiliation: Pulmonology Department-Muscle Wasting and Cachexia in Chronic Respiratory Diseases and Lung Cancer Research group, IMIM-Hospital del Mar, Parc de Salut Mar, Health and Experimental Sciences Department (CEXS), Universitat Pompeu Fabra (UPF), Barcelona, Spain.|Centro de Investigación en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III (ISCIII), Barcelona, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Barreiro
mesh_terms: D000107:Acetylation; D000818:Animals; D001835:Body Weight; D044127:Epigenesis, Genetic; D005260:Female; D019417:Hindlimb Suspension; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D024510:Muscle Development / Q000235:genetics; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology*; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D016474:Weight-Bearing
chemical_list: D006657:Histones; D035683:MicroRNAs; D014157:Transcription Factors; D006655:Histone Deacetylases