Expression and subcellular localization of apical junction proteins in canine duodenal and colonic mucosa.

ABSTRACT

OBJECTIVE: To examine the expression and distribution of tight junction (TJ) and adherens junction (AJ) proteins in canine duodenal and colonic mucosa. SAMPLE Mucosa obtained from 4 healthy Beagles. PROCEDURES Biopsy specimens of the duodenum and colon were obtained via endoscopy from 4 healthy dogs. The expression patterns and subcelluar localization of claudin-1, -2, -3, -4, -5, -7, and -8; E-cadherin; and ß-catenin in the duodenum and colon were analyzed by use of immunoblotting and immunofluorescence microscopy. RESULTS: In the duodenum, there was clear expression of claudin-3 and -5, E-cadherin, and ß-catenin proteins and weak expression of claudin-7 protein. In contrast, there was clear expression of claudin-2 and -3, E-cadherin, and ß-catenin proteins and weak expression of claudin-5 and -7 proteins in the colon, as determined by use of immunoblotting. As determined by the use of immunofluorescence microscopy, the duodenum and colon had staining for claudin-3 and -5, E-cadherin, and ß-catenin in the most apical region and staining for claudin-7 in the basolateral region. Staining for claudin-2 was also observed in the colon. CONCLUSIONS AND CLINICAL RELEVANCE Information was provided about the expression patterns of TJ and AJ proteins in the duodenum and colon of clinically normal dogs. These results may provide valuable information for use in evaluating the importance of these TJ and AJ proteins in the pathogenesis of inflammatory bowel disease in dogs.