Characterization of a strong positive cis-acting element of the human beta-myosin heavy chain gene in fetal rat heart cells.
A strong positive element within the proximal promoter region of the human beta-myosin heavy chain (beta-MHC) gene that is required for high level expression in primary cultures of fetal rat heart cells was localized by transient assays and DNase I footprinting to positions- 277/-298. Using gel shift studies, this sequence was found to bind specifically at high affinity (Kd approximately 4 x 10(-9) M) to a transcriptional factor (beta F1) found in nuclear extracts from rabbit heart. Dimethyl sulfate interference studies suggested that beta F1 may bind as a dimer to two hexameric imperfect direct repeats containing the consensus sequence 5'-(C/G)-T-G-(T/A)-G-G-3'. Gel shift analyses suggested that beta F1 is related to the M-CAT factor, which is known to control muscle-specific expression of the cardiac troponin T gene. A clustered mutation of the region between the putative binding half-sites and within the "M-CAT"-like domain abolished beta-MHC promoter activity. The sequence of the positive element also contains binding motifs for several transcriptional factors that regulate viral and cellular genes, including AP4, AP5, TEF-1, and MyoD-like proteins. When multiple copies of the beta-MHC element were inserted downstream from the transcriptional initiation site of the thymidine kinase gene, it did not act as a classical enhancer, showing some dependence upon orientation.
Flink
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IL
University Heart Center, Tucson, Arizona.
Edwards
J G
JG
Bahl
J J
JJ
Liew
C C
CC
Sole
M
M
Morkin
E
E
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003850:Deoxyribonuclease I; D004742:Enhancer Elements, Genetic; D005333:Fetus; D006367:HeLa Cells; D006321:Heart / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000502:physiology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009218:Myosins / Q000235:genetics*; D009687:Nuclear Proteins / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic; D011817:Rabbits; D051381:Rats; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D014158:Transcription, Genetic
D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D003850:Deoxyribonuclease I; D009218:Myosins