UROGUANYLIN AND GUANYLIN - DISTINCT BUT OVERLAPPING PATTERNS OF MESSENGER-RNA EXPRESSION IN MOUSE INTESTINE

Background & Aims: Uroguanylin and guanylin, endogenous ligands of the guanylate cyclase C receptor, are presumed to mediate fluid and elect rolyte secretion in the intestine. The aim of this study was to charac terize the expression patterns of uroguanylin and guanylin messenger R NA (mRNA) in the mouse intestine. Methods: A mouse uroguanylin complem entary DNA was amplified from a partial genomic clone, and Northern an alyses and in situ hybridization were performed to localize guanylin a nd uroguanylin mRNA along the duodenal-colonic and crypt-villus axes. Results: Uroguanylin mRNA was expressed throughout the mouse intestine and also in the kidney. Signal intensity was greatest in the small in testine for uroguanylin and in the distal small intestine and colon fo r guanylin. In situ hybridization showed uroguanylin mRNA localized pr edominantly in intestinal villi and the corticomedullary junction of t he kidney, whereas guanylin mRNA was localized in both crypts and vill i in the small intestine and to superficial epithelial cells in the co lon. Conclusions: Mouse uroguanylin mRNA expression is discrete from g uanylin expression in the intestine. The patterns of distribution in t he intestine and the known pH optima of these ligands suggest a comple mentary role for these secretagogues.