title: Role of CCAAT enhancer-binding protein beta in the thyroid hormone and cAMP induction of phosphoenolpyruvate carboxykinase gene transcription.
abstract: Transcription of the gene for phosphoenolpyruvate carboxykinase (PEPCK) is stimulated by thyroid hormone (T3) and cAMP. Two DNA elements in the PEPCK promoter are required for T3 responsiveness including a thyroid hormone response element and a binding site called P3(I) for the CCAAT enhancer-binding protein (C/EBP). Both the alpha and beta isoforms of C/EBP are highly expressed in the liver. C/EBPalpha contributes to the liver-specific expression and cAMP responsiveness of the PEPCK gene. In this study, we examined the ability of C/EBPbeta when bound to the P3(I) site to regulate PEPCK gene expression. We report that C/EBPbeta can stimulate basal expression and participate in the induction of PEPCK gene transcription by T3 and cAMP. The cAMP-responsive element-binding protein and AP1 proteins that contribute to the induction by cAMP are not involved in the stimulation by T3. A small region of the transactivation domain of C/EBPbeta is sufficient for the stimulation of basal expression and cAMP responsiveness. Our results suggest that C/EBPalpha and C/EBPbeta are functionally interchangeable when bound to the P3(I) site of the PEPCK promoter.
authors.affiliation: Department of Pharmacology, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA. epark@utmem1.utmem.edu
authors.forename: E A
authors.initials: EA
authors.lastname: Park
authors.forename: S
authors.initials: S
authors.lastname: Song
authors.forename: C
authors.initials: C
authors.lastname: Vinson
authors.forename: W J
authors.initials: WJ
authors.lastname: Roesler
mesh_terms: D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D002460:Cell Line; D000242:Cyclic AMP / Q000502:physiology*; D004247:DNA; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000235:genetics*; D013963:Thyroid Hormones / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology*; D014162:Transfection
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D013963:Thyroid Hormones; D004247:DNA; D000242:Cyclic AMP; D019764:Phosphoenolpyruvate Carboxykinase (ATP)