title: Regulation of the sodium/sulfate co-transporter by farnesoid X receptor alpha.
abstract: Fxralpha is known to regulate a variety of metabolic processes, including bile acid, cholesterol, and carbohydrate metabolism. In this study, we show direct evidence that Fxralpha is a key player in maintaining sulfate homeostasis. We identified and characterized the sodium/sulfate co-transporter (NaS-1; Slc13a1) as an Fxralpha target gene expressed in the kidney and intestine. Electromobility shift assays, chromatin immunoprecipitation, and promoter reporter studies identified a single functional Fxralpha response element in the second intron of the mouse Slc13a1 gene. Treatment of wild-type mice with GW4064, a synthetic Fxralpha agonist, induced Slc13a1 mRNA in the intestine and kidney. Slc13a1 mRNA was also induced in the kidney and intestine of wild-type, but not Fxralpha-/- mice, after treatment with the hepatotoxin alpha-naphthylisothiocyanate, which is known to result in elevated blood bile acid levels. Finally, we observed a decrease in Slc13a1 mRNA in the kidney and intestine of Fxralpha-/- mice and a corresponding increase in urinary excretion of free sulfates as compared with wild-type mice. These results demonstrate that mouse Slc13a1 is a novel Fxralpha target gene expressed in the kidney and intestine and that in the absence of Fxralpha, mice waste sulfate into the urine. Thus, Fxralpha is necessary for normal sulfate homeostasis in vivo.
authors.affiliation: Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Hans
authors.initials: H
authors.lastname: Lee
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Hubbert
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Osborne
authors.forename: Katherine
authors.initials: K
authors.lastname: Woodford
authors.forename: Noa
authors.initials: N
authors.lastname: Zerangue
authors.forename: Peter A
authors.initials: PA
authors.lastname: Edwards
mesh_terms: D000818:Animals; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D017353:Gene Deletion; D006706:Homeostasis; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D016601:RNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D000077003:Sodium Sulfate Cotransporter; D013431:Sulfates / Q000097:blood / Q000652:urine; D027981:Symporters / Q000235:genetics / Q000378:metabolism*
chemical_list: D027682:Cation Transport Proteins; D017931:DNA Primers; C096916:FXR1 protein, human; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D000077003:Sodium Sulfate Cotransporter; D013431:Sulfates; D027981:Symporters; D012313:RNA