title: Expression of anoctamin 1/TMEM16A by interstitial cells of Cajal is fundamental for slow wave activity in gastrointestinal muscles.
abstract: Interstitial cells of Cajal (ICC) generate pacemaker activity (slow waves) in gastrointestinal (GI) smooth muscles, but the mechanism(s) of pacemaker activity are controversial. Several conductances, such as Ca(2+)-activated Cl() channels (CaCC) and non-selective cation channels (NSCC) have been suggested to be involved in slow wave depolarization. We investigated the expression and function of a new class of CaCC, anoctamin 1 (ANO1), encoded by Tmem16a, which was discovered to be highly expressed in ICC in a microarray screen. GI muscles express splice variants of the Tmem16a transcript in addition to other paralogues of the Tmem16a family. ANO1 protein is expressed abundantly and specifically in ICC in all regions of the murine, non-human primate (Macaca fascicularis) and human GI tracts. CaCC blocking drugs, niflumic acid and 4,4-diisothiocyano-2,2-stillbene-disulfonic acid (DIDS) reduced the frequency and blocked slow waves in murine, primate, human small intestine and stomach in a concentration-dependent manner. Unitary potentials, small stochastic membrane depolarizations thought to underlie slow waves, were insensitive to CaCC blockers. Slow waves failed to develop by birth in mice homozygous for a null allele of Tmem16a (Tmem16a(tm1Bdh)(/tm1Bdh)) and did not develop subsequent to birth in organ culture, as in wildtype and heterozygous muscles. Loss of function of ANO1 did not inhibit the development of ICC networks that appeared structurally normal as indicated by Kit antibodies. These data demonstrate the fundamental role of ANO1 in the generation of slow waves in GI ICC.
authors.affiliation: Department of Physiology & Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
authors.forename: Sung Jin
authors.initials: SJ
authors.lastname: Hwang
authors.forename: Peter J A
authors.initials: PJ
authors.lastname: Blair
authors.forename: Fiona C
authors.initials: FC
authors.lastname: Britton
authors.forename: Kate E
authors.initials: KE
authors.lastname: O'Driscoll
authors.forename: Grant
authors.initials: G
authors.lastname: Hennig
authors.forename: Yulia R
authors.initials: YR
authors.lastname: Bayguinov
authors.forename: Jason R
authors.initials: JR
authors.lastname: Rock
authors.forename: Brian D
authors.initials: BD
authors.lastname: Harfe
authors.forename: Kenton M
authors.initials: KM
authors.lastname: Sanders
authors.forename: Sean M
authors.initials: SM
authors.lastname: Ward
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000075369:Anoctamin-1; D018118:Chloride Channels; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D041981:Gastrointestinal Tract / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D056885:Interstitial Cells of Cajal / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008252:Macaca fascicularis; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009544:Niflumic Acid / Q000494:pharmacology; D012313:RNA / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C476213:ANO1 protein, human; D000075369:Anoctamin-1; D018118:Chloride Channels; D016861:Cyclooxygenase Inhibitors; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D009544:Niflumic Acid; D012313:RNA; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid
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