Muscle stem cell behavior is modified by microRNA-27 regulation of Pax3 expression.
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.
Crist
Colin G
CG
Centre National de Recherche Scientifique Unité de Recherche Associée 2578, Department of Developmental Biology, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris Cedex 15, France.
Montarras
Didier
D
Pallafacchina
Giorgia
G
Rocancourt
Didier
D
Cumano
Ana
A
Conway
Simon J
SJ
Buckingham
Margaret
M
D020413:3' Untranslated Regions / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002460:Cell Line; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000166:cytology* / Q000502:physiology; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics* / Q000378:metabolism; D012038:Regeneration; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology / Q000378:metabolism; D019170:Somites / Q000196:embryology / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*
D020413:3' Untranslated Regions; D035683:MicroRNAs; C540674:Mirn27 microRNA, mouse; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; C068686:Pax3 protein, mouse