title: Cellular localization of TWIK-1, a two-pore-domain potassium channel in the rodent inner ear.
abstract: K(+) channels in the inner ear regulate the secretion and homeostasis of K(+), i.e. the flux of K(+) ions required to ensure good mechanosensory transduction. We studied the expression and cellular localization of TWIK-1 and TWIK-2, two-pore-domain K(+) channels responsible for background K(+) currents. Reverse transcription-polymerase chain reaction showed that TWIK-1 mRNA is present in the vestibular end organs, vestibular ganglion and cochlea. In contrast, the TWIK-2 mRNA was not detected in the inner ear. Immunocytochemical experiments using confocal microscopy showed that TWIK-1 is specifically localized in 'non-sensory' cells of the inner ear, in the dark cells of the vestibule and in the strial marginal cells of the cochlea. All of these cell types secrete and regulate the K(+) endolymph production and homeostasis. The labeling was strictly limited to the apical membranes of these cells. TWIK-1 was also detected in the cytoplasm of the large neurons of vestibular ganglion and their fibers. The finding that TWIK-1 is specifically distributed in certain areas of the inner ear suggests that this type of K(+) channel plays a role in the regulation of K(+) homeostasis in dark cells and in strial marginal cells. This role has yet to be identified.
authors.affiliation: Inserm U 432, Université Montpellier 2, Place Eugène Bataillon, PO Box 089, 34095 Cedex 05, Montpellier, France. mnicolas@crit.univ-montp2.fr
authors.forename: M T
authors.initials: MT
authors.lastname: Nicolas
authors.forename: J
authors.initials: J
authors.lastname: Barhanin
authors.forename: R
authors.initials: R
authors.lastname: Reyes
authors.forename: D
authors.initials: D
authors.lastname: Demêmes
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000378:metabolism; D003051:Cochlea / Q000378:metabolism; D007758:Ear, Inner / Q000166:cytology* / Q000378:metabolism*; D005724:Ganglia / Q000378:metabolism; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D015221:Potassium Channels / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D024683:Potassium Channels, Tandem Pore Domain; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D011984:Sensory Receptor Cells / Q000378:metabolism; D014018:Tissue Distribution; D014725:Vestibular Nerve / Q000378:metabolism
chemical_list: C486372:Kcnk1 protein, mouse; C487530:Kcnk1 protein, rat; C492208:Kcnk6 protein, mouse; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger; C059983:potassium channel protein I(sk)