title: Aldosterone-induced osteopontin gene transcription in vascular smooth muscle cells involves glucocorticoid response element.
abstract: Osteopontin (OPN) is known to be one of the cytokines that is involved in the vascular inflammation caused by aldosterone (Aldo). Previous reports have shown that Aldo increases OPN transcripts, and the mechanisms for this remain to be clarified. In this study, we investigated how Aldo increases OPN transcripts in the vascular smooth muscle cells of rats. Aldosterone increased OPN transcripts time-dependently as well as dose-dependently. This increase was diminished by eplerenone, a mineralocorticoid receptor (MR) antagonist. Luciferase promoter assays showed that the OPN promoter deleted to the -1599 site retained the same promoting ability as the full-length OPN promoter when stimulated by 10(-7) M Aldo, but the promoter deleted to the -1300 site lost the promoting ability. A glucocorticoid response element (GRE) is located in that deleted region. Luciferase assays of a mutated promoter without the GRE lost the luciferase upregulation, although mutated promoters with the deletion of other consensus sites maintained the promoter activity. The binding of the Aldo-MR complex to the GRE fragment was confirmed by an electrophoretic-mobility shift assay. This is the first report showing that Aldo regulates the transcriptional levels of OPN and inflammatory responses in the vasculature through a specific GRE site in the OPN promoter region.
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medicine, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Arihiro
authors.initials: A
authors.lastname: Kiyosue
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nagata
authors.forename: Masahiro
authors.initials: M
authors.lastname: Myojo
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Sato
authors.forename: Masao
authors.initials: M
authors.lastname: Takahashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Satonaka
authors.forename: Ryozo
authors.initials: R
authors.lastname: Nagai
authors.forename: Yasunobu
authors.initials: Y
authors.lastname: Hirata
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D024202:Electrophoretic Mobility Shift Assay; D005938:Glucocorticoids / Q000502:physiology*; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D053495:Osteopontin / Q000096:biosynthesis* / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D020218:Response Elements; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: D005938:Glucocorticoids; D053495:Osteopontin; D000450:Aldosterone