Expression of the ClC-5 chloride channel in gastric parietal cells

Abstract

The gastric H ⁺,K⁺–ATPase is involved in the proton secreting mechanism. It is unclear what molecule contributes to the secretion of Cl^–. We previously found that ClC–2 may not be a Cl^– transporting protein for the gastric acid secretion. Here, we examined the expression of another ClC chloride channel, ClC–5, which is abundant in the kidney. Western blot analysis using an anti–ClC–5 antibody showed that ClC–5 is expressed in hog gastric vesicles that are rich in H ⁺,K⁺–ATPase. Double staining with the ClC–5 and H ⁺,K⁺–ATPase antibodies on the hog gastric glands revealed that ClC–5 colocalizes with H ⁺,K⁺–ATPase in the parietal cells. Immunoprecipitation using the anti–H ⁺,K⁺–ATPase antibody demonstrated ClC–5 may bind to H ⁺,K⁺–ATPase in hog gastric vesicles. Furthermore, transient expression of ClC–5 protein in HEK293 cells expressing H ⁺,K⁺–ATPase increased the H ⁺,K⁺–ATPase activity by 20%. ClC–5 is known to be involved in endocytosis in the renal proximal tubular cells where it colocalizes with H ⁺–ATPase. In gastric parietal cells, ClC–5 may be involved in acid secretion in association with H ⁺,K⁺–ATPase. [Jpn J Physiol 55 Suppl:S78 (2005)]