title: Transcription factor GATA-4 regulates cardiac muscle-specific expression of the alpha-myosin heavy-chain gene.
abstract: The alpha-myosin heavy-chain (alpha-MHC) gene is the major structural protein in the adult rodent myocardium. Its expression is restricted to the heart by a complex interplay of trans-acting factors and their cis-acting sites. However, to date, the factors that have been shown to regulate expression of this gene have also been found in skeletal muscle cells. Recently, transcription factor GATA-4, which has a tissue distribution limited to the heart and endodermally derived tissues, was identified. We recently found two putative GATA-binding sites within the proximal enhancer of the alpha-MHC gene, suggesting that GATA-4 might regulate its expression. In this study, we establish that GATA-4 interacts with the alpha-MHC GATA sites to stimulate cardiac muscle-specific expression. Mutation of the GATA-4-binding sites either individually or together decreased activity by 50 and 88% in the adult myocardium, respectively. GATA-4-dependent enhancement of activity from a heterologous promoter was mediated through the alpha-MHC GATA sites. Coinjection of an alpha-MHC promoter construct with a GATA-4 expression vector permitted ectopic expression in skeletal muscle but not in fibroblasts. Thus, the lack of alpha-MHC expression in skeletal muscle correlates with a lack of GATA-4. GATA-4 DNA binding activity was significantly up-regulated in triiodothyronine- or retinoic acid-treated cardiomyocytes. Putative GATA-4-binding sites are also found in the regulatory regions of other cardiac muscle-expressed structural genes. This indicates a mechanism whereby triiodothyronine and retinoic acid can exert coordinate control of the cardiac phenotype through a trans-acting regulatory factor.
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee 53226.
authors.forename: J D
authors.initials: JD
authors.lastname: Molkentin
authors.forename: D V
authors.initials: DV
authors.lastname: Kalvakolanu
authors.forename: B E
authors.initials: BE
authors.lastname: Markham
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D050991:GATA4 Transcription Factor; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D007668:Kidney; D008156:Luciferases / Q000096:biosynthesis; D008297:Male; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009206:Myocardium / Q000378:metabolism*; D009218:Myosins / Q000096:biosynthesis* / Q000235:genetics*; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D016335:Zinc Fingers; D001616:beta-Galactosidase / Q000096:biosynthesis
chemical_list: D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; D009838:Oligodeoxyribonucleotides; D014157:Transcription Factors; D008156:Luciferases; D015500:Chloramphenicol O-Acetyltransferase; D001616:beta-Galactosidase; D009218:Myosins