PMID:9065755

Citation	Murphy, AM, Thompson, WR, Peng, LF and Jones, L 2nd (1997) Regulation of the rat cardiac troponin I gene by the transcription factor GATA-4. Biochem. J. 322 ( Pt 2):393-401
Abstract	Troponin I is a thin-filament contractile protein expressed in striated muscle. There are three known troponin I genes which are expressed in a muscle-fibre-type-specific manner in mature animals. Although the slow skeletal troponin I isoform is expressed in fetal and neonatal heart, the cardiac isoform is restricted in its expression to the myocardium at all developmental stages. To study the regulation of this cardiac-specific and developmentally regulated gene in vitro, the rat cardiac troponin I gene was cloned. Transient transfection assays were performed with troponin I-luciferase fusion plasmids to characterize the regulatory regions of the gene. Proximal regions of the upstream sequence were sufficient to support high levels of expression of the reporter gene in cardiocytes and relatively low levels in other cell types. The highest luciferase activity in the cardiocytes was noted with a plasmid that included the region spanning -896 to +45 of the troponin I genomic sequence. Co-transfection of GATA-4, a recently identified cardiac transcription factor, with troponin I-luciferase constructs permitted high levels of luciferase expression in non-cardiac cells. Electrophoretic mobility-shift assays demonstrated specific binding of GATA-4 to oligonucleotides representative of multiple sites of the troponin I sequence. Mutation of a proximal GATA-4 DNA-binding site decreased transcriptional activation in transfected cardiocytes. These results indicate that the proximal cardiac troponin I sequence is sufficient to support high levels of cardiac-specific gene expression and that the GATA-4 transcription factor regulates troponin I-luciferase expression in vitro.
Links	PubMed PMC1218204
Keywords	3T3 Cells; Amino Acid Sequence; Animals; Base Sequence; Binding Sites; DNA Mutational Analysis; DNA-Binding Proteins/metabolism; GATA4 Transcription Factor; Gene Expression Regulation, Developmental; Genes, Reporter; Mice; Molecular Sequence Data; Myocardium/metabolism; Promoter Regions, Genetic; Protein Binding; Rats; Recombinant Fusion Proteins/biosynthesis; Tissue Distribution; Transcription Factors/metabolism; Transcription, Genetic; Troponin I/biosynthesis; Troponin I/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
RAT:TNNI3	involved_in	GO:0006937: regulation of muscle contraction	ECO:0000304: author statement supported by traceable reference used in manual assertion		P		Seeded From UniProt	complete

References

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