miR-206 represses hypertrophy of myogenic cells but not muscle fibers via inhibition of HDAC4

• Published in: PloS one 2013-09, Vol.8 (9), p.e73589-e73589
• Main Authors: Winbanks, Catherine E, Beyer, Claudia, Hagg, Adam, Qian, Hongwei, Sepulveda, Patricio V, Gregorevic, Paul
• Format: Article
• Language: English
• Subjects: Adaptation; Analysis; Animal models; Animals; Atrophy; Cell culture; Cell Line; Cloning; Denervation; Dependovirus - genetics; Development and progression; Diabetes; Drug development; Follistatin; Gene expression; Genetic aspects; Genetic Vectors - genetics; Heart; Histone deacetylase; Histone Deacetylases - genetics; Hypertrophy; Hypertrophy - genetics; In vivo methods and tests; Inhibition; Metabolism; Mice; MicroRNA; MicroRNAs; MicroRNAs - genetics; miRNA; Muscle Development; Muscle Fibers, Skeletal - cytology; Muscle Fibers, Skeletal - enzymology; Muscle Fibers, Skeletal - pathology; Muscle Fibers, Skeletal - physiology; Muscles; Muscular Atrophy - genetics; Musculoskeletal system; Myotubes; Nutrition research; Obesity; Overexpression; Physiological aspects; Physiology; Plasmids; Protein biosynthesis; Protein synthesis; Proteins; Ribonucleic acid; RNA; Rodents; Skeletal muscle; Sodium; Sodium butyrate; Transferases; Valproic acid
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0073589

microRNAs regulate the development of myogenic progenitors, and the formation of skeletal muscle fibers. However, the role miRNAs play in controlling the growth and adaptation of post-mitotic musculature is less clear. Here, we show that inhibition of the established pro-myogenic regulator miR-206 can promote hypertrophy and increased protein synthesis in post-mitotic cells of the myogenic lineage. We have previously demonstrated that histone deacetylase 4 (HDAC4) is a target of miR-206 in the regulation of myogenic differentiation. We confirmed that inhibition of miR-206 de-repressed HDAC4 accumulation in cultured myotubes. Importantly, inhibition of HDAC4 activity by valproic acid or sodium butyrate prevented hypertrophy of myogenic cells otherwise induced by inhibition of miR-206. To test the significance of miRNA-206 as a regulator of skeletal muscle mass in vivo, we designed recombinant adeno-associated viral vectors (rAAV6 vectors) expressing miR-206, or a miR-206 "sponge," featuring repeats of a validated miR-206 target sequence. We observed that over-expression or inhibition of miR-206 in the muscles of mice decreased or increased endogenous HDAC4 levels respectively, but did not alter muscle mass or myofiber size. We subsequently manipulated miR-206 levels in muscles undergoing follistatin-induced hypertrophy or denervation-induced atrophy (models of muscle adaptation where endogenous miR-206 expression is altered). Vector-mediated manipulation of miR-206 activity in these models of cell growth and wasting did not alter gain or loss of muscle mass respectively. Our data demonstrate that although the miR-206/HDAC4 axis operates in skeletal muscle, the post-natal expression of miR-206 is not a key regulator of basal skeletal muscle mass or specific modes of muscle growth and wasting. These studies support a context-dependent role of miR-206 in regulating hypertrophy that may be dispensable for maintaining or modifying the adult skeletal muscle phenotype--an important consideration in relation to the development of therapeutics designed to manipulate microRNA activity in musculature.