A functional tandem between transient receptor potential canonical channels 6 and calcium-dependent chloride channels in human epithelial cells.
TRPC6 plays important human physiological functions, notably in artery and arterioles constriction, in regulation of vascular volume and in bronchial muscle constriction. It is implicated in pulmonary hypertension, cardiovascular disease, and focal segmental glomerulosclerosis and seems to play a role in cancer development. Previously, we identified Guanabenz, an α2-adrenergic agonist used for hypertension treatment (Wytensin®), as an activator of calcium-dependent chloride channels (CaCC) in human Cystic Fibrosis (CF) nasal epithelial cells by transiently increasing [Ca2+]i via an influx of extracellular Ca2+. In this study, using assays to measure chloride channel activity, we show that guanabenz is an activator of CaCC in freshly dissociated human bronchial epithelial cells from three CF patients with various genotypes (F508del/F508del, F508del/R1066C, F508del/H1085R). We further characterised the effect of guanabenz and show that it is independent of α-adrenergic receptors, is inhibited by the TRPC family inhibitor SKF-96365 but not by the TRPV family inhibitor ruthenium red. Using western-blotting, Ca2+ measurements and iodide efflux assay, we found that TRPC1 siRNA has no effect on guanabenz induced responses whereas TRPC6 siRNA prevented the guanabenz-dependent Ca2+ influx and the CaCC-dependent activity stimulated by guanabenz. In conclusion, we show that TRPC6 channel is pivotal for the activation of CaCC by guanabenz through a α2-adrenergic-independent pathway in human airway epithelial cells. We suggest propose a functional coupling between TRPC6 and CaCC and guanabenz as a potential TRPC6 activator for exploring TRPC6 and CaCC channel functions and corresponding channelopathies.
Laboratoire Signalisation et Transports Ioniques Membranaires, Université de Poitiers-CNRS, Pôle Biologie Santé, 1 rue Georges Bonnet, 86073 Poitiers Cedex 9, France.
Johanna
J
Bertrand
Laboratoire Signalisation et Transports Ioniques Membranaires, Université de Poitiers-CNRS, Pôle Biologie Santé, 1 rue Georges Bonnet, 86073 Poitiers Cedex 9, France.
Luc
L
Dannhoffer
Laboratoire Signalisation et Transports Ioniques Membranaires, Université de Poitiers-CNRS, Pôle Biologie Santé, 1 rue Georges Bonnet, 86073 Poitiers Cedex 9, France.
Fabrice
F
Antigny
Laboratoire Signalisation et Transports Ioniques Membranaires, Université de Poitiers-CNRS, Pôle Biologie Santé, 1 rue Georges Bonnet, 86073 Poitiers Cedex 9, France.
Laura
L
Vachel
Service de Chirurgie Cardiothoracique, CHU La Milétrie, 2 rue de la Miletrie, 86021 Poitiers, France.
Christophe
C
Jayle
Laboratoire Signalisation et Transports Ioniques Membranaires, Université de Poitiers-CNRS, Pôle Biologie Santé, 1 rue Georges Bonnet, 86073 Poitiers Cedex 9, France.
Clarisse
C
Vandebrouck
Laboratoire Signalisation et Transports Ioniques Membranaires, Université de Poitiers-CNRS, Pôle Biologie Santé, 1 rue Georges Bonnet, 86073 Poitiers Cedex 9, France.
Frédéric
F
Becq
Laboratoire Signalisation et Transports Ioniques Membranaires, Université de Poitiers-CNRS, Pôle Biologie Santé, 1 rue Georges Bonnet, 86073 Poitiers Cedex 9, France. Electronic address: caroline.norez@univ-poitiers.fr.
Caroline
C
Norez
D000328:Adult; D000584:Amiloride / Q000494:pharmacology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D062686:Epithelial Sodium Channel Blockers / Q000494:pharmacology; D005260:Female; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D020545:Respiratory Mucosa / Q000187:drug effects / Q000378:metabolism; D050052:TRPC Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000074287:TRPC6 Cation Channel; D055815:Young Adult
D018118:Chloride Channels; D062686:Epithelial Sodium Channel Blockers; D007093:Imidazoles; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; D000584:Amiloride; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole
Calcium-activated chloride channel; Cystic fibrosis; Human airway epithelial cells; Pharmacology; Transient receptor potential canonical channel