The E box is essential for activity of the cardiac actin promoter in skeletal but not in cardiac muscle.
The sequence CANNTG (E box) is frequently found in the promoters of muscle-specific genes and binds members of the basic helix-loop-helix (bHLH) family of transcription factors. We compared the need for the E box in the expression of a muscle-specific promoter normally expressed in both cardiac and skeletal muscle. The E box was mutated in a construct of the cardiac alpha-actin promoter driving the Escherichia coli lacZ gene. The wild-type and mutant constructs were transfected and stably integrated into the genomes of P19 embryonal carcinoma cells. The wild-type promoter was expressed in both cardiac and skeletal myocytes. The promoter lacking an E box was expressed in cardiac but not in skeletal muscle. Neither promoter was active in nonmuscle cells. Thus the E box is not necessary for the cardiac actin promoter activity in P19-derived cardiac muscle but is essential for its activity in skeletal muscle. This result is consistent with our inability to detect cardiac muscle-specific members of the MyoD family of bHLH transcription factors.
Skerjanc
I S
IS
Department of Medicine, University of Ottawa, Ontario, Canada.
McBurney
M W
MW
D000199:Actins / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D054278:Embryonal Carcinoma Stem Cells; D015870:Gene Expression; D018257:Helix-Loop-Helix Motifs; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D014411:Neoplastic Stem Cells / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000032:analysis
D000199:Actins; D014157:Transcription Factors