title: Fibroblast growth factor receptor 3 gene transcription is suppressed by cyclic adenosine 3',5'-monophosphate. Identification of a chondrocytic regulatory element.
abstract: Signaling through fibroblast growth factor receptors (FGFRs) is critical for the development and patterning of the vertebrate skeleton. Gain-of-function alleles of fgfr2 and fgfr3 have been linked to several dominant skeletal disorders in humans, while null mutations in fgfr3 result in the overgrowth of long bones in a mouse model system. Interestingly, the expression pattern of fgfr3 in growth plate chondrocytes overlaps that of the parathyroid hormone (PTH)-related peptide (PTHrP) receptor, a signaling molecule that also regulates endochondral ossification. The coincident expression of these two receptors suggests that their signaling pathways may also interact. To gain insight into the regulatory mechanism(s) that govern the expression of the fgfr3 gene in chondrocytes, we have identified a cell-specific transcriptional regulatory element (CSRh) by measuring the activity of various promoter fragments in FGFR3-expressing (CFK2) and nonexpressing (RCJ) chondrocyte-like cell lines. Furthermore, we demonstrate that activation of PTH/PTHrP receptors, either by stimulation with PTH or through the introduction of activating mutations, represses CSRh-mediated transcriptional activity. Finally, the transcriptional repression of the CSRh element was mimicked by treatment with forskolin, 8-bromo-cAMP, and 3-isobutyl-1-methylxanthine or by overexpression of the catalytic subunit of protein kinase A. Together, these data suggest that protein kinase A activity is a critical factor that regulates fgfr3 gene expression in the proliferative or prehypertrophic compartment of the epiphyseal growth plate. Furthermore, these results provide a possible link between PTHrP signaling and fgfr3 gene expression during the process of endochondral ossification.
authors.affiliation: Department of Molecular Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: D G
authors.initials: DG
authors.lastname: McEwen
authors.forename: R P
authors.initials: RP
authors.lastname: Green
authors.forename: M C
authors.initials: MC
authors.lastname: Naski
authors.forename: D A
authors.initials: DA
authors.lastname: Towler
authors.forename: D M
authors.initials: DM
authors.lastname: Ornitz
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology*; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006132:Growth Plate / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000378:metabolism; D010281:Parathyroid Hormone / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases; D051498:Receptor, Fibroblast Growth Factor, Type 3; D044168:Receptor, Parathyroid Hormone, Type 1; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics*; D018016:Receptors, Parathyroid Hormone / Q000235:genetics*; D011994:Recombinant Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D009838:Oligodeoxyribonucleotides; D010281:Parathyroid Hormone; D044168:Receptor, Parathyroid Hormone, Type 1; D017468:Receptors, Fibroblast Growth Factor; D018016:Receptors, Parathyroid Hormone; D011994:Recombinant Proteins; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; C496365:FGFR3 protein, human; C496366:Fgfr3 protein, mouse; D011505:Protein-Tyrosine Kinases; D051498:Receptor, Fibroblast Growth Factor, Type 3; D015056:1-Methyl-3-isobutylxanthine