Localization of Cystic Fibrosis Transmembrane Conductance Regulator

We have used in situ hybridization to localize expression of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in the human gastrointestinal tract and associated organs. The stomach exhibits a low level ofCFTR expression throughout gastric mucosa. In the small intestine, expression is relatively high in the mucosal epithelium, with a decreasing gradient of expression along the crypt to tip axis. The cells of the Brunner's glands express high levels ofCFTR mRNA. In addition, there is a small subpopulation of highly positive cells scattered along the epithelium in the duodenum and jejunum, but not in the ileum. These cells do not represent endocrine cells, as determined by lack of colocalization with an endocrine-specific marker. The distribution ofCFTR mRNA in the colon is similar to the small intestine, with highest level of expression in the epithelial cells at the base of the crypts. In the pancreas, CFIR is expressed at high levels in the small, intercalated ducts and at lower levels in the interlobular ducts. CFI'R transcripts are expressed at uniformly high levels in the epithelium of the gallbladder. Throughout the gastrointestinal tract, CFTR expression is increased in mucosal epithelial cells that are near lymph nodules. (J. Clin. Invest. 1994. 93:347-354.)