title: Hormone-specific regulation of the kidney androgen-regulated gene promoter in cultured mouse renal proximal-tubule cells.
abstract: The kidney androgen-regulated protein (KAP) is specifically expressed and differentially regulated by androgens and tri-iodothyronine (T(3)) in intact mouse early (PCT) and late (PR) proximal-tubule cells. Until now, detailed characterization of the molecular elements mediating androgen-responsive gene expression in the kidney has been hampered by the lack of appropriate cultured cell systems suitable for DNA transfection studies. In the present study we have analysed the hormone-dependent transactivation of the KAP gene promoter in immortalized differentiated PCT and PR proximal-tubule cells derived from L-PK/Tag1 transgenic mice. Transient transfection studies with different KAP promoter constructs indicated that a 224 bp-truncated fragment was sufficient to mediate cell-specific expression of the KAP promoter. Dihydrotestosterone (DHT) stimulated in an androgen-dependent manner the transactivation of KAP in PCT and PR cells, while mutation of a putative androgen-response element (ARE) sequence located at -39 bp from the transcription initiation site abolished the transactivation induced by DHT. Furthermore, insulin-like growth factor 1 (IGF-1), but not T(3), enhanced the androgen-dependent transactivation of KAP in cultured PCT cells. These results demonstrate that the short 224 bp fragment of the KAP promoter is sufficient to drive the proximal-tubule androgen-specific regulated expression of KAP and reveal synergistic interactions between IGF-1 and androgens for KAP regulation in PCT cells.
authors.affiliation: Centre d'Investigacions en Bioquimica i Biologia Molecular (CIBBIM), Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain.
authors.forename: Montse
authors.initials: M
authors.lastname: Soler
authors.forename: Olga
authors.initials: O
authors.lastname: Tornavaca
authors.forename: Esther
authors.initials: E
authors.lastname: Solé
authors.forename: Anna
authors.initials: A
authors.lastname: Menoyo
authors.forename: Dianne
authors.initials: D
authors.lastname: Hardy
authors.forename: James F
authors.initials: JF
authors.lastname: Catterall
authors.forename: Alain
authors.initials: A
authors.lastname: Vandewalle
authors.forename: Anna
authors.initials: A
authors.lastname: Meseguer
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D017930:Genes, Reporter; D006728:Hormones / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008957:Models, Genetic; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013963:Thyroid Hormones / Q000494:pharmacology; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: D006728:Hormones; C067670:Kap protein, mouse; D011506:Proteins; D013963:Thyroid Hormones; D007334:Insulin-Like Growth Factor I; D008156:Luciferases; D015500:Chloramphenicol O-Acetyltransferase; D010744:Phosphoric Monoester Hydrolases