Calcium-activated chloride channels in the apical region of mouse vomeronasal sensory neurons.
The rodent vomeronasal organ plays a crucial role in several social behaviors. Detection of pheromones or other emitted signaling molecules occurs in the dendritic microvilli of vomeronasal sensory neurons, where the binding of molecules to vomeronasal receptors leads to the influx of sodium and calcium ions mainly through the transient receptor potential canonical 2 (TRPC2) channel. To investigate the physiological role played by the increase in intracellular calcium concentration in the apical region of these neurons, we produced localized, rapid, and reproducible increases in calcium concentration with flash photolysis of caged calcium and measured calcium-activated currents with the whole cell voltage-clamp technique. On average, a large inward calcium-activated current of -261 pA was measured at -50 mV, rising with a time constant of 13 ms. Ion substitution experiments showed that this current is anion selective. Moreover, the chloride channel blockers niflumic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid partially inhibited the calcium-activated current. These results directly demonstrate that a large chloride current can be activated by calcium in the apical region of mouse vomeronasal sensory neurons. Furthermore, we showed by immunohistochemistry that the calcium-activated chloride channels TMEM16A/anoctamin1 and TMEM16B/anoctamin2 are present in the apical layer of the vomeronasal epithelium, where they largely colocalize with the TRPC2 transduction channel. Immunocytochemistry on isolated vomeronasal sensory neurons showed that TMEM16A and TMEM16B coexpress in the neuronal microvilli. Therefore, we conclude that microvilli of mouse vomeronasal sensory neurons have a high density of calcium-activated chloride channels that may play an important role in vomeronasal transduction.
Neurobiology Sector and Italian Institute of Technology Unit, Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy.
Michele
M
Dibattista
Asma
A
Amjad
Devendra Kumar
DK
Maurya
Claudia
C
Sagheddu
Giorgia
G
Montani
Roberto
R
Tirindelli
Anna
A
Menini
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000085:Acetates / Q000494:pharmacology; D000818:Animals; D000075369:Anoctamin-1; D000075368:Anoctamins; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D065101:Chloride Channel Agonists; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005029:Ethylenediamines / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D051379:Mice; D008871:Microvilli / Q000378:metabolism; D009544:Niflumic Acid / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010782:Photolysis; D011984:Sensory Receptor Cells / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D050052:TRPC Cation Channels / Q000378:metabolism; D019147:Vomeronasal Organ / Q000166:cytology / Q000378:metabolism* / Q000502:physiology
C531181:ANO1 protein, mouse; C532161:ANO2 protein, mouse; D000085:Acetates; D000075369:Anoctamin-1; D000075368:Anoctamins; D002614:Chelating Agents; D065101:Chloride Channel Agonists; D018118:Chloride Channels; D005029:Ethylenediamines; D050052:TRPC Cation Channels; C491858:Trpc2 protein, mouse; C057014:DM-nitrophen; D009544:Niflumic Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium