title: Functional expression of the TMEM16 family of calcium-activated chloride channels in airway smooth muscle.
abstract: Airway smooth muscle hyperresponsiveness is a key component in the pathophysiology of asthma. Although calcium-activated chloride channel (CaCC) flux has been described in many cell types, including human airway smooth muscle (HASM), the true molecular identity of the channels responsible for this chloride conductance remains controversial. Recently, a new family of proteins thought to represent the true CaCCs was identified as the TMEM16 family. This led us to question whether members of this family are functionally expressed in native and cultured HASM. We further questioned whether expression of these channels contributes to the contractile function of HASM. We identified the mRNA expression of eight members of the TMEM16 family in HASM cells and show immunohistochemical evidence of TMEM16A in both cultured and native HASM. Functionally, we demonstrate that the classic chloride channel inhibitor, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), inhibited halide flux in cultured HASM cells. Moreover, HASM cells displayed classical electrophysiological properties of CaCCs during whole cell electrophysiological recordings, which were blocked by using an antibody selective for TMEM16A. Furthermore, two distinct TMEM16A antagonists (tannic acid and benzbromarone) impaired a substance P-induced contraction in isolated guinea pig tracheal rings. These findings demonstrate that multiple members of this recently described family of CaCCs are expressed in HASM cells, they display classic electrophysiological properties of CaCCs, and they modulate contractile tone in airway smooth muscle. The TMEM16 family may provide a novel therapeutic target for limiting airway constriction in asthma.
authors.affiliation: Dept. of Anesthesiology, 622 W. 168th St. P&S Box 46, Columbia Univ. College of Physicians and Surgeons, New York, NY 10032. gg2125@columbia.edu.
authors.forename: George
authors.initials: G
authors.lastname: Gallos
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Remy
authors.forename: Jennifer
authors.initials: J
authors.lastname: Danielsson
authors.forename: Hiromi
authors.initials: H
authors.lastname: Funayama
authors.forename: Xiao Wen
authors.initials: XW
authors.lastname: Fu
authors.forename: Herng-Yu Sucie
authors.initials: HY
authors.lastname: Chang
authors.forename: Peter
authors.initials: P
authors.lastname: Yim
authors.forename: Dingbang
authors.initials: D
authors.lastname: Xu
authors.forename: Charles W
authors.initials: CW
authors.lastname: Emala
mesh_terms: D000818:Animals; D000075369:Anoctamin-1; D000075368:Anoctamins; D001249:Asthma / Q000473:pathology / Q000503:physiopathology*; D001553:Benzbromarone / Q000494:pharmacology; D001980:Bronchi / Q000166:cytology / Q000502:physiology*; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D002908:Chronic Disease; D006168:Guinea Pigs; D006801:Humans; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D005810:Multigene Family / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000502:physiology*; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D018408:Patch-Clamp Techniques; D061251:Primary Cell Culture; D013634:Tannins / Q000494:pharmacology; D014132:Trachea / Q000166:cytology / Q000502:physiology*
chemical_list: C476213:ANO1 protein, human; C521849:ANO2 protein, human; D000075369:Anoctamin-1; D000075368:Anoctamins; D018118:Chloride Channels; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D013634:Tannins; D001553:Benzbromarone
keywords: MQAE; RT-PCR; airway smooth muscle; electrophysiology; immunohistochemistry