Expression of calcium-activated chloride channels Ano1 and Ano2 in mouse taste cells.
Specialized Ca(2+)-dependent ion channels ubiquitously couple intracellular Ca(2+) signals to a change in cell polarization. The existing physiological evidence suggests that Ca(2+)-activated Cl(-) channels (CaCCs) are functional in taste cells. Because Ano1 and Ano2 encode channel proteins that form CaCCs in a variety of cells, we analyzed their expression in mouse taste cells. Transcripts for Ano1 and Ano2 were detected in circumvallate (CV) papillae, and their expression in taste cells was confirmed using immunohistochemistry. When dialyzed with CsCl, taste cells of the type III exhibited no ion currents dependent on cytosolic Ca(2+). Large Ca(2+)-gated currents mediated by TRPM5 were elicited in type II cells by Ca(2+) uncaging. When TRPM5 was inhibited by triphenylphosphine oxide (TPPO), ionomycin stimulated a small but resolvable inward current that was eliminated by anion channel blockers, including T16Ainh-A01 (T16), a specific Ano1 antagonist. This suggests that CaCCs, including Ano1-like channels, are functional in type II cells. In type I cells, CaCCs were prominently active, blockable with the CaCC antagonist CaCCinh-A01 but insensitive to T16. By profiling Ano1 and Ano2 expressions in individual taste cells, we revealed Ano1 transcripts in type II cells only, while Ano2 transcripts were detected in both type I and type II cells. P2Y agonists stimulated Ca(2+)-gated Cl(-) currents in type I cells. Thus, CaCCs, possibly formed by Ano2, serve as effectors downstream of P2Y receptors in type I cells. While the role for TRPM5 in taste transduction is well established, the physiological significance of expression of CaCCs in type II cells remains to be elucidated.
['Cherkashin|Alexander P|AP|', 'Kolesnikova|Alisa S|AS|', 'Tarasov|Michail V|MV|', 'Romanov|Roman A|RA|', 'Rogachevskaja|Olga A|OA|', 'Bystrova|Marina F|MF|', 'Kolesnikov|Stanislav S|SS|']
D000200:Action Potentials D000818:Animals D000075369:Anoctamin-1 D000075368:Anoctamins D016466:CHO Cells D002118:Calcium D002478:Cells, Cultured D018118:Chloride Channels D006224:Cricetinae D003412:Cricetulus D057809:HEK293 Cells D006801:Humans D051379:Mice D058921:Purinergic P2Y Receptor Antagonists D012333:RNA, Messenger D058470:Receptors, Purinergic P2Y D050053:TRPM Cation Channels D013650:Taste Buds
Ano1 Ano2 Taste cells Ca2+-gated Cl− channels Purinergic transduction