title: MEF2A regulates the Gtl2-Dio3 microRNA mega-cluster to modulate WNT signaling in skeletal muscle regeneration.
abstract: Understanding the molecular mechanisms of skeletal muscle regeneration is crucial to exploiting this pathway for use in tissue repair. Our data demonstrate that the MEF2A transcription factor plays an essential role in skeletal muscle regeneration in adult mice. Injured Mef2a knockout mice display widespread necrosis and impaired myofiber formation. MEF2A controls this process through its direct regulation of the largest known mammalian microRNA (miRNA) cluster, the Gtl2-Dio3 locus. A subset of the Gtl2-Dio3 miRNAs represses secreted Frizzled-related proteins (sFRPs), inhibitors of WNT signaling. Consistent with these data, Gtl2-Dio3-encoded miRNAs are downregulated in regenerating Mef2a knockout muscle, resulting in upregulated sFRP expression and attenuated WNT activity. Furthermore, myogenic differentiation in Mef2a-deficient myoblasts is rescued by overexpression of miR-410 and miR-433, two miRNAs in the Gtl2-Dio3 locus that repress sFRP2, or by treatment with recombinant WNT3A and WNT5A. Thus, miRNA-mediated modulation of WNT signaling by MEF2A is a requisite step for proper muscle regeneration, and represents an attractive pathway for enhancing regeneration of diseased muscle.
authors.affiliation: Department of Biology, Program in Cell and Molecular Biology, Boston University, Boston, MA 02215, USA.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Snyder
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Rice
authors.forename: Nelsa L
authors.initials: NL
authors.lastname: Estrella
authors.forename: Aaron
authors.initials: A
authors.lastname: Held
authors.forename: Susan C
authors.initials: SC
authors.lastname: Kandarian
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Naya
mesh_terms: D000818:Animals; D019556:COS Cells; D002232:Carbocyanines / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D051157:Frizzled Receptors / Q000235:genetics; D055785:Gene Knockdown Techniques; D006801:Humans; D064326:MEF2 Transcription Factors; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000502:physiology*; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000502:physiology*; D062085:RNA, Long Noncoding / Q000235:genetics* / Q000378:metabolism*; D012038:Regeneration / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D015854:Up-Regulation / Q000235:genetics; D051153:Wnt Proteins / Q000378:metabolism* / Q000502:physiology
chemical_list: D002232:Carbocyanines; D051157:Frizzled Receptors; D064326:MEF2 Transcription Factors; C422882:MEG3 non-coding RNA, mouse; C578036:Mef2a protein, mouse; D035683:MicroRNAs; D018006:Myogenic Regulatory Factors; D062085:RNA, Long Noncoding; D051153:Wnt Proteins; C015843:3,3'-dipropyloxadicarbocyanine