Uroguanylin gene expression in the alimentary tract and extra-gastrointestinal tissues

Uroguanylin, a member of the guanylin peptide family, is a novel peptide regulator for intestinal salt and water transport. A cDNA encoding a precursor for rat uroguanylin was cloned from a rat jejunum cDNA library and sequenced, The precursor tvas 106 amino acids long and included a 21 residue putative signal peptide at the N-terminus. Rat uroguanylin consisted of 15 amino acids similar to, but distinct front human uroguanylin; the C-terminal leucine residue nas deleted and 3 residues were substituted compared to those in the human peptide, Synthetic rat uroguanylin-15 dose-dependently increased the cyclic GMP level in cultured T84 cells, RNA blot analysis showed that rat uroguanylin mRNA is expressed not only iu the gastrointestinal tract but also in the lung, pancreas and kidney. Evidence for uroguanylin expression in extra-gastrointestinal tissues indicates the possible existence of a novel sq stem for water and electrolyte homeostasis, and a more global effect of uroguanylin on epithelial cell function.