Spatiotemporal expression of TRPM4 in the mouse cochlea.
The present study was conducted to elucidate the presence of the transient receptor potential cation channel subfamily M member 4, TRPM4, in the mouse inner ear. TRPM4 immunoreactivity (IR) was found in the cell body of inner hair cells (IHCs) in the organ of Corti in the apical side of marginal cells of the stria vascularis, in the apical portion of the dark cells of the vestibule, and in a subset of the type II neurons in the spiral ganglion. Subsequently, changes in the distribution and expression of TRPM4 in the inner ear during embryonic and postnatal developments were also evaluated. Immunohistochemical localization demonstrated that the emergence of the TRPM4-IR in IHCs occurs shortly before the onset of hearing, whereas that in the marginal cells happens earlier, at the time of birth, coinciding with the onset of endolymph formation. Furthermore, semiquantitative real-time PCR assay showed that expressions of TRPM4 in the organ of Corti and in the stria vascularis increased dramatically at the onset of hearing. Because TRPM4 is a Ca(2+) -activated monovalent-selective cation channel, these findings imply that TRPM4 contributes to potassium ion transport, essential for the signal transduction in IHCs and the formation of endolymph by marginal cells.
Department of Otorhinolaryngology, Juntendo University Graduate School of Medicine, Tokyo, Japan.
Mayumi
M
Sakuraba
Junko
J
Murata
Ryoichi
R
Teruyama
Kazusaku
K
Kamiya
Junji
J
Yamaguchi
Hideyuki
H
Okano
Yasuo
Y
Uchiyama
Katsuhisa
K
Ikeda
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002462:Cell Membrane / Q000378:metabolism; D003051:Cochlea / Q000033:anatomy & histology* / Q000254:growth & development / Q000378:metabolism*; D004622:Embryo, Mammalian; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D006199:Hair Cells, Auditory, Inner / Q000378:metabolism*; D006309:Hearing / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018995:Myosin Heavy Chains / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000378:metabolism; D013136:Spiral Ganglion / Q000166:cytology; D050053:TRPM Cation Channels / Q000235:genetics / Q000378:metabolism*
D050053:TRPM Cation Channels; C476766:TRPM4 protein, mouse; C089785:myosin VI; D018995:Myosin Heavy Chains
TRP channel; endolymph; inner hair cell; marginal cell; stria vascularis