Muscle stem cell behavior is modified by microRNA-27 regulation of Pax3 expression

• Published in: Proceedings of the National Academy of Sciences - PNAS 2009-08, Vol.106 (32), p.13383-13387
• Main Authors: Crist, Colin G, Montarras, Didier, Pallafacchina, Giorgia, Rocancourt, Didier, Cumano, Ana, Conway, Simon J, Buckingham, Margaret
• Format: Article
• Language: English
• Subjects: 3' Untranslated Regions; 3' Untranslated Regions - metabolism; Animals; Artificial satellites; Base Sequence; Biological Sciences; Cell adhesion & migration; Cell culture; Cell Differentiation; Cell Line; Cells; Cellular differentiation; Embryo, Mammalian; Embryo, Mammalian - cytology; Embryo, Mammalian - metabolism; Embryology; Embryonic stem cells; Embryos; Gene expression; Gene Expression Regulation, Developmental; Humans; Immunology; Life Sciences; Mice; Mice, Transgenic; MicroRNA; MicroRNAs; MicroRNAs - genetics; MicroRNAs - metabolism; Molecular Sequence Data; Muscle, Skeletal; Muscle, Skeletal - cytology; Muscle, Skeletal - physiology; Musculoskeletal system; Paired Box Transcription Factors; Paired Box Transcription Factors - genetics; Paired Box Transcription Factors - metabolism; PAX3 Transcription Factor; Progenitor cells; Proteins; Regeneration; Satellite Cells, Skeletal Muscle; Satellite Cells, Skeletal Muscle - cytology; Satellite Cells, Skeletal Muscle - metabolism; Skeletal muscle; Skeletal muscle satellite cells; Somites; Somites - embryology; Somites - metabolism; Stem Cells; Stem Cells - cytology; Stem Cells - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0900210106

Skeletal muscle stem cells are regulated by Pax3/7. During development, Pax3 is required for the maintenance of these cells in the somite and their migration to sites of myogenesis; high levels of Pax3 interfere with muscle cell differentiation, both in the embryo and in the adult. Quantitative fine-tuning of Pax3 is critical, and microRNAs provide a potential mechanism. We identify microRNA-27b (miR-27b), which directly targets the 3'-UTR of Pax3 mRNA, as such a regulator. miR-27b is expressed in the differentiating skeletal muscle of the embryonic myotome and in activated satellite cells of adult muscle. In vivo overexpression of a miR-27b transgene in Pax3-positive cells in the embryo leads to down-regulation of Pax3, resulting in interference with progenitor cell migration and in premature differentiation. In a complementary experiment, miR-27b inhibitors were transfected into cultures of adult muscle satellite cells that normally express miR-27b at the onset of differentiation, when Pax3 protein levels undergo rapid down-regulation. Interference with miR-27b function results in continuing Pax3 expression leading to more proliferation and a delay in the onset of differentiation. Pax7 levels are not affected. Introduction of miR-27b antagomirs at a site of muscle injury in vivo also affects Pax3 expression and regeneration in vivo. We therefore conclude that miR-27b regulates Pax3 protein levels and this down-regulation ensures rapid and robust entry into the myogenic differentiation program.