title: MyoD or Myf-5 is required for the formation of skeletal muscle.
abstract: Mice carrying null mutations in the myogenic regulatory factors Myf-5 or MyoD have apparently normal skeletal muscle. To address whether these two factors functionally substitute for one another in myogenesis, mice carrying mutant Myf-5 and MyoD genes were interbred. While mice lacking both MyoD and Myf-5 were born alive, they were immobile and died soon after birth. Northern blot and S1 nuclease analyses indicated that Myf-5(-1-);MyoD(-1-) mice expressed no detectable skeletal muscle-specific mRNAs. Histological examination of these mice revealed a complete absence of skeletal muscle. Immunohistochemical analysis indicated an absence of desmin-expressing myoblast-like cells. These observations suggest that either Myf-5 or MyoD is required for the determination of skeletal myoblasts, their propagation, or both during embryonic development and indicate that these factors play, at least in part, functionally redundant roles in myogenesis.
authors.affiliation: Institute for Molecular Biology and Biotechnology, McMaster University, Hamilton, Ontario, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Rudnicki
authors.forename: P N
authors.initials: PN
authors.lastname: Schnegelsberg
authors.forename: R H
authors.initials: RH
authors.lastname: Stead
authors.forename: T
authors.initials: T
authors.lastname: Braun
authors.forename: H H
authors.initials: HH
authors.lastname: Arnold
authors.forename: R
authors.initials: R
authors.lastname: Jaenisch
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins; D005260:Female; D015870:Gene Expression; D018257:Helix-Loop-Helix Motifs; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009124:Muscle Proteins / Q000235:genetics / Q000502:physiology*; D009132:Muscles / Q000196:embryology*; D009154:Mutation; D017570:MyoD Protein / Q000235:genetics / Q000502:physiology*; D051787:Myogenic Regulatory Factor 5; D012333:RNA, Messenger / Q000235:genetics; D015534:Trans-Activators
chemical_list: D004268:DNA-Binding Proteins; D009124:Muscle Proteins; C497418:Myf5 protein, mouse; D017570:MyoD Protein; D051787:Myogenic Regulatory Factor 5; D012333:RNA, Messenger; D015534:Trans-Activators