title: Renal expression of organic anion transporter OAT2 in rats and mice is regulated by sex hormones.
abstract: The renal reabsorption and/or excretion of various organic anions is mediated by specific organic anion transporters (OATs). OAT2 (Slc22a7) has been identified in rat kidney, where its mRNA expression exhibits gender differences [females (F) > males (M)]. The exact localization of OAT2 protein in the mammalian kidney has not been reported. Here we studied the expression of OAT2 mRNA by RT-PCR and its protein by Western blotting (WB) and immunocytochemistry (IC) in kidneys of adult intact and gonadectomized M and F, sex hormone-treated castrated M, and prepubertal M and F rats, and the protein in adult M and F mice. In adult rats, the expression of OAT2 mRNA was predominant in the outer stripe (OS) tissue, exhibiting 1) gender dependency (F > M), 2) upregulation by castration and downregulation by ovariectomy, and 3) strong downregulation by testosterone and weak upregulation by estradiol and progesterone treatment. A polyclonal antibody against rat OAT2 on WB of isolated renal membranes labeled a approximately 66-kDa protein band that was stronger in F. By IC, the antibody exclusively stained brush border (BB) of the proximal tubule S3 segment (S3) in the OS and medullary rays (F > M). In variously treated rats, the pattern of 66-kDa band density in the OS membranes and the staining intensity of BB in S3 matched the mRNA expression. The expression of OAT2 protein in prepubertal rats was low and gender independent. In mice, the expression pattern largely resembled that in rats. Therefore, OAT2 in rat (and mouse) kidney is localized to the BB of S3, exhibiting gender differences (F > M) that appear in puberty and are caused by strong androgen inhibition and weak estrogen and progesterone stimulation.
authors.affiliation: Molecular Toxicology, Institute for Medical Research and Occupational Health, Zagreb, Croatia.
authors.forename: Marija
authors.initials: M
authors.lastname: Ljubojević
authors.forename: Daniela
authors.initials: D
authors.lastname: Balen
authors.forename: Davorka
authors.initials: D
authors.lastname: Breljak
authors.forename: Marija
authors.initials: M
authors.lastname: Kusan
authors.forename: Naohiko
authors.initials: N
authors.lastname: Anzai
authors.forename: Andrew
authors.initials: A
authors.lastname: Bahn
authors.forename: Gerhard
authors.initials: G
authors.lastname: Burckhardt
authors.forename: Ivan
authors.initials: I
authors.lastname: Sabolić
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D015153:Blotting, Western; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D012739:Gonadal Steroid Hormones / Q000502:physiology*; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism*; D008297:Male; D051379:Mice; D009919:Orchiectomy; D029362:Organic Anion Transporters, Sodium-Independent / Q000096:biosynthesis*; D010052:Ovariectomy; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012727:Sex Characteristics; D012741:Sexual Maturation; D016707:Tissue Fixation
chemical_list: D017931:DNA Primers; D012739:Gonadal Steroid Hormones; D029362:Organic Anion Transporters, Sodium-Independent; D012333:RNA, Messenger; C088800:Slc22a7 protein, rat