title: pCLCA1 becomes a cAMP-dependent chloride conductance mediator in Caco-2 cells.
abstract: Members of the CLCA protein family are expressed in airway and intestinal epithelium, where they may participate in secretory activity as mediators of chloride conductance. A calcium-dependent chloride conductance has been observed upon expression of CLCA proteins in non-epithelial cell lines. The pCLCA1 gene, cloned in our laboratory, codes for a product containing a unique A-kinase consensus acceptor site not found in other CLCA proteins. Calcium-dependent, but not cAMP-dependent, chloride conductance increased when pCLCA1 was expressed in NIH/3T3 fibroblasts. We transfected the Caco-2 human colon carcinoma cell line with pCLCA1 to investigate the regulation of CLCA-associated chloride conductance in this differentiated epithelial cell line. Expression of pCLCA1 in the Caco-2 cell line enhanced cAMP-responsive 36Cl efflux, short circuit current, and whole cell chloride current in these cells. This cAMP-dependent chloride conductance was localized to the apical membrane of polarized Caco-2 cells.
authors.affiliation: Department of Veterinary Biomedical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan, Canada S7N 5B4.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Loewen
authors.forename: Lane K
authors.initials: LK
authors.lastname: Bekar
authors.forename: Sherif E
authors.initials: SE
authors.lastname: Gabriel
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Walz
authors.forename: George W
authors.initials: GW
authors.lastname: Forsyth
mesh_terms: D001483:Base Sequence; D018938:Caco-2 Cells; D018118:Chloride Channels / Q000502:physiology*; D002712:Chlorides / Q000502:physiology*; D000242:Cyclic AMP / Q000502:physiology*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics; D017931:DNA Primers; D006801:Humans; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C505032:CFTR protein, human; C492109:CLCA1 protein, human; D018118:Chloride Channels; D002712:Chlorides; D017931:DNA Primers; D012333:RNA, Messenger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000242:Cyclic AMP