engleski

Immunolocalization of chloride-formate exchanger (Slc26a6) in various rat tissues ; sex-dependent expression in kidneys

Chloride-formate exchanger (CFEX), a member of the Solute carrier family 26 (Slc26a6), in various mammalian organs mediates transport of chloride, bicarbonate, oxalate, formate and hydroxyl ions. Its cellular localization in rat organs/tissues is poorly documented. Here we used a commercial polyclonal anti-CFEX antibody (CFEX-Ab) to investigate the CFEX protein expression in the kidneys, intestine, liver and pancreas of Wistar rats by immunofluorescence cytochemistry (IFC) in tissue cryosections and by Western blotting (WB) of total cell membranes (TCM) isolated from the respective organs. To determine sex-dependent renal expression, the CFEX protein abundance was studied in the kidneys of prepubertal, adult intact and gonadectomized rats of both sexes, and of sex hormone-treated castrates. By IFC, the CFEX-Ab stained the brush-border membrane (BBM) of proximal tubules with heterogeneous intensity (S1~S2>S3), other nephron segments being CFEX-negative. The renal CFEX protein expression was a) male-dominant, b) downregulated by castration, c) not affected by ovariectomy, d) upregulated by androgen treatment, and e) low and sex-independent in prepubertal animals. In the intestine, CFEX was localized in the BBM of duodenal and jejunal enterocytes (duodenumjejunum) ; no staining was seen in the ileum, caecum and colon. By WB of TCM, the CFEX-Ab labeled a single protein band of 120 kDa whose density matched the IFC findings. The protein was also immunolocalized to the hepatocyte canalicular membrane and apical domain of pancreatic ducts. Therefore, the CFEX protein is expressed in various rat organs/tissues, whereas in the kidneys, its expression is male-dominant due to post-pubertal androgen stimulation.

androgens ; brush-border membrane ; gastrointestinal tract ; liver ; pancreas ; proximal tubule

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