Slc26a3, also known as DRA (down-regulated in adenoma), is a key chloride-bicarbonate exchanger protein in the intestinal epithelial luminal membrane. It participates in the electroneutral NaCl absorption of the intestine, together with Na+/H+ exchangers, and is crucial for maintaining the acid-base homeostasis of the intestinal epithelium [2].

In DRA-knockout (KO) mice, there is an increased colonic paracellular permeability with decreased levels of tight junction/adherens junction proteins like ZO-1, occludin, and E-cadherin, indicating a role in maintaining intestinal epithelial barrier integrity. These mice also exhibit gut dysbiosis, but it plays only a partial role in tight junction protein expression. Post-transcriptional mechanisms seem to be key in gut barrier dysfunction in these KO mice [1]. Slc26a3 -/- mice also show a more acidic colonic pH microclimate, decreased goblet cell thecae per crypt, reduced mucus accumulation, decreased colonic luminal microbiome diversity, and increased mucosal TNFα mRNA expression levels and leucocyte infiltration, which may explain their increased susceptibility to DSS damage [5].

In conclusion, Slc26a3 is essential for intestinal electrolyte absorption and maintaining the integrity of the intestinal epithelial barrier. Gene-knockout mouse models, such as DRA-KO and Slc26a3 -/-, have revealed its role in gut barrier function, microbiome composition, and pH microclimate regulation. These findings have implications for understanding diseases like inflammatory bowel disease (IBD), congenital chloride diarrhea, and potentially other intestinal disorders [1,3,4,5].