Expression of myogenic factors in the mouse: myf-5, the first member of the MyoD gene family to be transcribed during skeletal myogenesis.
There are four myogenic factors of the MyoD family present in mammals, each have distinct patterns of expression during skeletal myogenesis in the mouse. This differs between axial (myotome) and peripheral (limb) muscle masses, which are derived from the medial and lateral parts of the somite, respectively. The onset of expression of the muscle structural genes also differs, suggesting differences in their activation threshold in response to different factors. In all cases myf-5 is the first gene to be expressed. In order to examine this more closely, we have introduced an nlsLacZ sequence into the myf-5 gene by homologous recombination. This has permitted us to follow expression of this gene at the cellular level. While the immediate precursors of the myotome are labelled, we have shown that peripheral muscle masses such as those in the limb are founded by muscle precursor cells which are initially myf-5 negative. At later stages of development the gene is transcribed in all skeletal muscles, irrespective of their origin and fibre type. We discuss the unexpected finding which was made with the myf-5/nlsLacZ mice, that myf-5 is also expressed in the central nervous system.
Buckingham
M
M
CNRS ERS 67, Département de Biologie Moléculaire, Institut Pasteur, Paris.
Tajbakhsh
S
S
D000818:Animals; D002490:Central Nervous System / Q000196:embryology; D004268:DNA-Binding Proteins; D015870:Gene Expression; D005809:Genes, Regulator; D051379:Mice; D008815:Mice, Inbred Strains; D009124:Muscle Proteins / Q000235:genetics*; D009132:Muscles / Q000737:chemistry* / Q000196:embryology*; D017570:MyoD Protein / Q000235:genetics*; D051787:Myogenic Regulatory Factor 5; D018008:Myogenin; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D009124:Muscle Proteins; C497418:Myf5 protein, mouse; D017570:MyoD Protein; C503801:Myog protein, mouse; D051787:Myogenic Regulatory Factor 5; D018008:Myogenin; D015534:Trans-Activators; D014157:Transcription Factors