Expression and localization of K channels KCNQ2 and KCNQ3 in the mammalian cochlea.
KCNQ1 and KCNQ4 voltage-gated potassium channel subunits play key roles in hearing. Other members of the KCNQ family also encode slow, low voltage-activated K(+) M currents. We have previously reported the presence of M-like K(+) currents in sensory hair cells, and expression of Kcnq family genes in the cochlea. Here, we describe Kcnq2/3 gene expression and distribution of M channel subunits KCNQ2 and 3 in the cochlea. By using RT-PCR, we found expression of Kcnq2 in the modiolus and organ of Corti, while Kcnq3 expression was also detected in the cochlear lateral wall. Five alternative splice variants of the Kcnq2 gene, one of which has not been reported previously, were identified in the rat cochlea. KCNQ2 and KCNQ3 immunoreactivities were observed in spiral ganglion auditory neurons. In addition, the unmyelinated parts of the nerve fibers innervating hair cells and synaptic regions under hair cells showed KCNQ2 immunoreactivity. KCNQ3 immunoreactivity was also prominent in spiral ganglion satellite cells. These findings suggest that cochlear M channels play important roles in regulation of cellular excitability and maintenance of cochlear K(+) homeostasis in the auditory system.
Jin
Zhe
Z
Center for Hearing and Communication Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. zhe.jin@med.lu.se
Liang
Gui-Hua
GH
Cooper
Edward C
EC
Jarlebark
Leif
L
D017398:Alternative Splicing; D000818:Animals; D000918:Antibody Specificity; D003051:Cochlea / Q000502:physiology*; D015870:Gene Expression / Q000502:physiology; D006168:Guinea Pigs; D006309:Hearing / Q000502:physiology; D007150:Immunohistochemistry; D051658:KCNQ2 Potassium Channel / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D051659:KCNQ3 Potassium Channel / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D008322:Mammals; D051379:Mice; D008810:Mice, Inbred C57BL; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013136:Spiral Ganglion / Q000502:physiology
D051658:KCNQ2 Potassium Channel; D051659:KCNQ3 Potassium Channel; C114401:Kcnq2 protein, mouse; C496915:Kcnq2 protein, rat; C496917:Kcnq3 protein, mouse; C496918:Kcnq3 protein, rat; D009419:Nerve Tissue Proteins