Characterization of a murine gene homologous to the bovine CaCC chloride channel

The bovine CaCC protein is a putative Ca2+-dependent Cl- channel of airway epithelial cells. Therefore, CaCC proteins could contribute to transepithel ial Cl- transport and accordingly modify the phenotype of cystic fibrosis ( CF) patients. We have identified a murine EST containing a full-length cDNA coding for a 902-amino-acid protein highly homologous to bovine CaCC. The murine gene (mCaCC) maps to chromosome 3 at the H2-H3 band and is expressed , as indicated by Northern blot analysis, in mouse skin and kidney but not in brain, heart, lung or testis. RT-PCR indicates a low expression in trach eal epithelial cells. Heterologous expression of mCaCC in Xenopus oocytes e licits membrane currents that are anion-selective and inhibited by DIDS and by niflumic acid, a blocker of the endogenous chloride current in oocytes. The identification of genes belonging to the CaCC family will help to eval uate their role as ion channels or channel regulators and their actual cont ribution to epithelial chloride transport. (C) 1999 Elsevier Science B.V. A ll rights reserved.