title: Role for early growth response-1 protein in alpha(1)-adrenergic stimulation of fibroblast growth factor-2 promoter activity in cardiac myocytes.
abstract: Fibroblast growth factor-2 (FGF-2), a mitogenic, angiogenic, and cardioprotective agent, is released from the postnatal heart by a mechanism of transient remodelling of the sarcolemma during contraction. Both release of FGF-2 and its synthesis can be increased with adrenergic stimulation. We reported previously that FGF-2 synthesis can be regulated at the transcriptional level by alpha-adrenergic stimulation of cultured neonatal rat cardiac myocytes as well as in the adult mouse heart. Examination of the proximal promoter region of both human and rat FGF-2 gene sequences revealed binding sites for the early growth response-1 (Egr-1) protein. Using gel mobility shift assays, we observed a transient increase in a complex between nuclear extracts from neonatal rat cardiac myocytes treated with inducers of Egr-1, including the alpha-adrenergic agonist phenylephrine, angiotensin II, and phorbol ester, and a consensus Egr-1 DNA element. A similar complex was seen with the FGF-2 promoter region -7/+42 as the DNA probe, but not when the Egr-1 element at nucleotides +3/+31 was disrupted. Participation of Egr-1 protein in the complex was confirmed by competition with Egr-1 DNA elements and antibodies. With deletion analysis and transfection of neonatal rat cardiac myocytes, the alpha-adrenergic response was localized to nucleotides -110/+42 of the FGF-2 gene in the context of a hybrid FGF-2/luciferase reporter gene, -110FGFp.luc. Overexpression of Egr-1 increased -110FGFp.luc gene expression, whereas mutation of its Egr-1 element at nucleotides +3/+31 abolished alpha-adrenergic responsiveness. These data indicate that Egr-1 is involved in the alpha-adrenergic stimulation of the FGF-2 promoter region in neonatal cardiac myocytes.
authors.affiliation: Gene Technology and Departments of Physiology, and Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Jin
authors.forename: F
authors.initials: F
authors.lastname: Sheikh
authors.forename: K A
authors.initials: KA
authors.lastname: Detillieux
authors.forename: P A
authors.initials: PA
authors.lastname: Cattini
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D051766:Early Growth Response Protein 1; D016222:Fibroblast Growth Factor 2 / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006321:Heart / Q000187:drug effects / Q000502:physiology; D006801:Humans; D017874:Immediate-Early Proteins; D051379:Mice; D009206:Myocardium / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D009687:Nuclear Proteins; D018340:Receptors, Adrenergic, alpha-1; D014157:Transcription Factors; D016222:Fibroblast Growth Factor 2; D000804:Angiotensin II; D010656:Phenylephrine; D004247:DNA; D013755:Tetradecanoylphorbol Acetate