Mouse R-cadherin: expression during the organogenesis of pancreas and gastrointestinal tract.

Members of the cadherin protein family of cell adhesion molecules are thought to regulate many morphogenetic events during the development of multicellular organisms. We are interested in which cell-cell interactions cadherins regulate during pancreas morphogenesis. Expression and function of E-cadherin in the pancreas have previously been characterized. Recently, R-cadherin cDNA was isolated and the expression patterns of R- and N-cadherin cDNA was isolated and the expression patterns of R- and N-cadherin mRNAs in the pancreas have been described. In the present study, we have investigated the expression of R-cadherin in the pancreas and gastrointestinal tract using specific anti-R-cadherin antibodies. During early stages of pancreas development (E10.5) R-cadherin is expressed in most hormone-producing cells in addition to in primitive duct-like cells. Later, at E18.5, when islets start to form, R-cadherin is not expressed in intraislet endocrine cells, but is instead found in intraductule endocrine and exocrine cells. In adult islets of Langerhans R-cadherin is absent from endocrine cells, but is present in ductule-like cells. Furthermore, the molecule is expressed in exocrine cells: apically and basolaterally on epithelial duct and ductule cells and apically on acinar cells. Interestingly, there appears to be a correlation between the downregulation of R-cadherin expression in intraductule endocrine cells and the migration out of the duct epithelium to form islets. In the gastrointestinal tract R-cadherin is expressed in the pit region of gastric glands and in absorptive cells of the small intestine. The subcellular localization in these tissues is on both the apical and basolateral surfaces. The potential function of R-cadherin, in particular its role in pancreas development, is discussed.