Transactivation of capn2 by myogenic regulatory factors during myogenesis.
The calcium-activated cysteine protease m-calpain plays a pivotal role during the earlier stages of myogenesis, particularly during fusion. The enzyme is a heterodimer, encoded by the genes capn2, for the large subunit, and capn4, for the small subunit. To study the regulation of m-calpain, the DNA sequence upstream of capn2 was analyzed for promoter elements, revealing the existence of five consensus-binding sites (E-box) for several myogenic regulatory factors and one binding site for myocyte enhancer factor-2 (MEF-2). Transient transfections with reporter gene constructs containing the E-box revealed that MyoD presents a high level of transactivation of reporter constructs containing this region, in particular the sequences including the MEF-2/E4-box. In addition, over-expression of various myogenic factors demonstrated that MyoD and myogenin with much less efficiency, can up-regulate capn2, both singly and synergistically, while Myf5 has no effect on synthesis of the protease. Experiments with antisense oligonucleotides directed against each myogenic factor revealed that MyoD plays a specific and pivotal role during capn2 regulation, and cannot be replaced wholly by myogenin and Myf5.
Dedieu
Stéphane
S
Laboratoire Biosciences de l'Aliment, ISTAB-USC-INRA 429, Université Bordeaux I, Avenue des Facultés, 33405 Talence Cedex, France.
Mazères
Germain
G
Dourdin
Nathalie
N
Cottin
Patrick
P
Brustis
Jean-Jacques
JJ
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015153:Blotting, Western; D019556:COS Cells; D002154:Calpain / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000502:physiology*; D005347:Fibroblasts / Q000502:physiology; D005786:Gene Expression Regulation; D006801:Humans; D007124:Immunoenzyme Techniques; D008156:Luciferases / Q000378:metabolism; D064326:MEF2 Transcription Factors; D051379:Mice; D008969:Molecular Sequence Data; D024510:Muscle Development / Q000502:physiology*; D009124:Muscle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000494:pharmacology; D017570:MyoD Protein / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000494:pharmacology; D032446:Myoblasts / Q000502:physiology*; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors; D018008:Myogenin / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation / Q000235:genetics*; D014162:Transfection; D015854:Up-Regulation
D017931:DNA Primers; D004268:DNA-Binding Proteins; D064326:MEF2 Transcription Factors; C497417:MYF5 protein, human; C503799:MYOG protein, human; D009124:Muscle Proteins; C497418:Myf5 protein, mouse; D017570:MyoD Protein; C503801:Myog protein, mouse; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors; D018008:Myogenin; D016376:Oligonucleotides, Antisense; D011994:Recombinant Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D008156:Luciferases; D002154:Calpain; C449000:m-calpain