title: Functional cooperation between CCAAT/enhancer-binding proteins and the vitamin D receptor in regulation of 25-hydroxyvitamin D3 24-hydroxylase.
abstract: 1,25-Dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] induces the synthesis of 25-hydroxyvitamin D(3) 24-hydroxylase [24(OH)ase], an enzyme involved in its catabolism, thereby regulating its own metabolism. Here we demonstrate that CCAAT enhancer binding protein beta (C/EBPbeta) is induced by 1,25(OH)(2)D(3) in kidney and in osteoblastic cells and is a potent enhancer of vitamin D receptor (VDR)-mediated 24(OH)ase transcription. Transfection studies indicate that 1,25(OH)(2)D(3) induction of 24(OH)ase transcription is enhanced a maximum of 10-fold by C/EBPbeta. Suppression of 1,25(OH)(2)D(3)-induced 24(OH)ase transcription was observed with dominant negative C/EBP or osteoblastic cells from C/EBPbeta(-/-) mice. A C/EBP site was identified at positions -395 to -388 (-395/-388) in the rat 24(OH)ase promoter. Mutation of this site inhibited C/EBPbeta binding and markedly attenuated the transcriptional response to C/EBPbeta. We also report the cooperation of CBP/p300 with C/EBPbeta in regulating VDR-mediated 24(OH)ase transcription. We found that not only 1,25(OH)(2)D(3) but also parathyroid hormone (PTH) can induce C/EBPbeta expression in osteoblastic cells. PTH potentiated the induction of C/EBPbeta and 24(OH)ase expression in response to 1,25(OH)(2)D(3) in osteoblastic cells. Data with the human VDR promoter (which contains two putative C/EBP sites) indicate a role for C/EBPbeta in the protein kinase A-mediated induction of VDR transcription. From this study a fundamental role has been established for the first time for cooperative effects and cross talk between the C/EBP family of transcription factors and VDR in 1,25(OH)(2)D(3)-induced transcription. These findings also indicate a novel role for C/EBPbeta in the cross talk between PTH and 1,25(OH)(2)D(3) that involves the regulation of VDR transcription.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, 185 South Orange Avenue, Newark, NJ 07103, USA.
authors.forename: Puneet
authors.initials: P
authors.lastname: Dhawan
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Peng
authors.forename: Amelia L M
authors.initials: AL
authors.lastname: Sutton
authors.forename: Paul N
authors.initials: PN
authors.lastname: MacDonald
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Croniger
authors.forename: Christian
authors.initials: C
authors.lastname: Trautwein
authors.forename: Michael
authors.initials: M
authors.lastname: Centrella
authors.forename: Thomas L
authors.initials: TL
authors.lastname: McCarthy
authors.forename: Sylvia
authors.initials: S
authors.lastname: Christakos
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001665:Binding Sites; D015152:Blotting, Northern; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism*; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry*; D015971:Gene Expression Regulation, Enzymologic; D047468:Immunoprecipitation; D007668:Kidney / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts / Q000378:metabolism; D010281:Parathyroid Hormone / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D018167:Receptors, Calcitriol / Q000378:metabolism*; D013250:Steroid Hydroxylases / Q000737:chemistry*; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D065668:Vitamin D3 24-Hydroxylase
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; D010281:Parathyroid Hormone; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D003577:Cytochrome P-450 Enzyme System; D008156:Luciferases; D013250:Steroid Hydroxylases; D065668:Vitamin D3 24-Hydroxylase; D015500:Chloramphenicol O-Acetyltransferase