Cloning of ClC-2 chloride channel from murine duodenum and its presence in CFTR knockout mice

We report the cloning of a murine ClC-2 chloride channel cDNA from duodenal epithelium by reverse transcriptase-polymerase chain reaction (RT-PCR) using degenerate primers and by rapid amplification of cDNA ends (RACE)-PCR. Other than CFTR, this represents the first cloned chloride channel from intact intestine. The ClC-2 cDNA predicts encoding of a 908 amino acid polypeptide with a calculated M(r) of 99,373. The amino acid sequence of the murine ClC-2 chloride channel is over 94% identical to the ClC-2 chloride channel proteins of other species. Of interest is the finding that the ClC-2 mRNA is expressed about the same level in duodena from both CFTR knockout and wild-type mice. This is in keeping with the suggestion that ClC-2 might be a therapeutic target in cystic fibrosis.