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XB-ART-5554
J Physiol 2003 May 15;549Pt 1:3-19. doi: 10.1113/jphysiol.2003.039818.
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Acute regulation of the SLC26A3 congenital chloride diarrhoea anion exchanger (DRA) expressed in Xenopus oocytes.

Chernova MN , Jiang L , Shmukler BE , Schweinfest CW , Blanco P , Freedman SD , Stewart AK , Alper SL .


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Mutations in the human SLC26A3 gene, also known as down-regulated in adenoma (hDRA), cause autosomal recessive congenital chloride-losing diarrhoea (CLD). hDRA expressed in Xenopus oocytes mediated bidirectional Cl--Cl- and Cl--HCO3- exchange. In contrast, transport of oxalate was low, and transport of sulfate and of butyrate was undetectable. Two CLD missense disease mutants of hDRA were nonfunctional in oocytes. Truncation of up to 44 C-terminal amino acids from the putatively cytoplasmic C-terminal hydrophilic domain left transport function unimpaired, but deletion of the adjacent STAS (sulfate transporter anti-sigma factor antagonist) domain abolished function. hDRA-mediated Cl- transport was insensitive to changing extracellular pH, but was inhibited by intracellular acidification and activated by NH4+ at acidifying concentrations. These regulatory responses did not require the presence of either hDRA's N-terminal cytoplasmic tail or its 44 C-terminal amino acids, but they did require more proximate residues of the C-terminal cytoplasmic domain. Although only weakly sensitive to inhibition by stilbenes, hDRA was inhibited with two orders of magnitude greater potency by the anti-inflammatory drugs niflumate and tenidap. cAMP-insensitive Cl--HCO3- exchange mediated by hDRA gained modest cAMP sensitivity when co-expressed with cystic fibrosis transmembrane conductance regulator (CFTR). Despite the absence of hDRA transcripts in human cell lines derived from CFTR patients, DRA mRNA was present at wild-type levels in proximal colon and nearly so in the distal ileum of CFTR(-/-) mice. Thus, pharmacological modulation of DRA might be a useful adjunct treatment of cystic fibrosis.

???displayArticle.pubmedLink??? 12651923
???displayArticle.pmcLink??? PMC2342915
???displayArticle.link??? J Physiol
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Species referenced: Xenopus
Genes referenced: camp cftr slc26a3.1 slc26a3.2
GO keywords: anion transport [+]

???displayArticle.disOnts??? congenital secretory chloride diarrhea 1 [+]
???displayArticle.omims??? DIARRHEA 1, SECRETORY CHLORIDE, CONGENITAL; DIAR1 [+]
References [+] :
Aichbichler, Proton-pump inhibition of gastric chloride secretion in congenital chloridorrhea. 1997, Pubmed