title: Genomic cloning, molecular characterization, and functional analysis of human CLCA1, the first human member of the family of Ca2+-activated Cl- channel proteins.
abstract: We have cloned and molecularly and functionally characterized the first human member of the family of Ca2+-activated Cl- channels, human (h) CLCA1. The 31,902-bp gene is located on chromosome 1p22-31 and is preceded by a canonic promoter region that contains an L1 transposable element. In contrast to all previously known homologs in other species, hCLCA1 is exclusively expressed in intestinal basal crypt epithelia and goblet cells, suggesting that it does not represent the human counterpart of any of them. Expression of the 914-amino-acid hCLCA1 protein in HEK 293 cells yielded a 125-kDa precursor that was processed to yield two cell-surface-associated subunits, a 90-kDa protein and a group of 37- to 41-kDa proteins. Four transmembrane domains were established within the 90-kDa subunit. HEK 293 cells transfected with CLCA1 exhibited an increase in whole-cell Ca2+-sensitive Cl- currents that were outwardly rectified and inhibited by 4,4'-diisothiocyanatostilbene-2, 2'-disulfonic acid, dithiothreitol, and niflumic acid. Cell-attached patch recordings of transfected cells revealed single channels with a slope conductance of 13.4 pS. These findings suggest that human CLCA1 mediates a Ca2+-activated Cl- conductance in the human intestine and make it an interesting candidate as a modulating factor in the pathogenesis of cystic fibrosis.
authors.affiliation: Cancer Biology Laboratories, Department of Molecular Medicine, Cornell University College of Veterinary Medicine, Ithaca, New York, 14853, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Gruber
authors.forename: R C
authors.initials: RC
authors.lastname: Elble
authors.forename: H L
authors.initials: HL
authors.lastname: Ji
authors.forename: K D
authors.initials: KD
authors.lastname: Schreur
authors.forename: C M
authors.initials: CM
authors.lastname: Fuller
authors.forename: B U
authors.initials: BU
authors.lastname: Pauli
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D002118:Calcium / Q000494:pharmacology; D002460:Cell Line; D018118:Chloride Channels / Q000235:genetics*; D002874:Chromosome Mapping; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics; D003001:Cloning, Molecular; D003550:Cystic Fibrosis / Q000235:genetics; D004229:Dithiothreitol / Q000494:pharmacology; D004594:Electrophysiology; D006801:Humans; D017403:In Situ Hybridization; D007413:Intestinal Mucosa / Q000378:metabolism; D008969:Molecular Sequence Data; D009544:Niflumic Acid / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D014176:Protein Biosynthesis / Q000235:genetics; D011499:Protein Processing, Post-Translational / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics; D014162:Transfection / Q000235:genetics
chemical_list: C492109:CLCA1 protein, human; D018118:Chloride Channels; D012333:RNA, Messenger; D014157:Transcription Factors; D009544:Niflumic Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium; D004229:Dithiothreitol