Inner ear abnormalities in a Kcnq1 (Kvlqt1) knockout mouse: a model of Jervell and Lange-Nielsen syndrome.
OBJECTIVE
Mice lacking functional KCNQ1 (previously known as KvLQT1) channels exhibit functional and structural abnormalities that indicate disturbed production of endolymph.


BACKGROUND
Congenital deafness associated with cardiac conduction abnormalities (Jervell and Lange-Nielsen syndrome) is associated with dysfunctional KCNQ1/KCNE1 channel complex. This potassium channel plays a critical role in the production and homeostasis of endolymph by the stria vascularis. A preliminary report documented severe abnormalities of the scala media and vestibular compartments of a single mouse lacking functional KCNQ1 alleles.


METHODS
Hearing thresholds were measured in three Kcnq1 knockout mice, two heterozygous mice, and one wild-type mouse by auditory brainstem response recordings using clicks, after which the temporal bones were removed. After fixation and dehydration, the ears were embedded in araldite, sectioned at 20-microm thickness, stained with toluidine blue on glass slides, and examined with the light microscope.


RESULTS
Kcnq1 knockout mice were deaf and demonstrated circling behavior. They exhibited a marked atrophy of the stria vascularis, contraction of the endolymphatic compartments, and collapse and adhesion of surrounding membranes. There was a complete degeneration of the organ of Corti and an associated degeneration of the spiral ganglion.


CONCLUSIONS
Kcnq1 knockout mice exhibit histopathologic findings that are comparable to those reported in human temporal bone cases of Jervell and Lange-Nielsen syndrome, and provide further evidence that KCNQ1 channel dysfunction can lead to congenital deafness in this syndrome.
Rivas
Alejandro
A
Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University, Baltimore, Maryland, USA.
Francis
Howard W
HW
D000818:Animals; D003051:Cochlea / Q000473:pathology; D004195:Disease Models, Animal; D007758:Ear, Inner / Q000002:abnormalities*; D006801:Humans; D029593:Jervell-Lange Nielsen Syndrome / Q000235:genetics*; D051656:KCNQ Potassium Channels; D051657:KCNQ1 Potassium Channel; D051379:Mice; D018345:Mice, Knockout; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics*; D014722:Vestibule, Labyrinth / Q000473:pathology
D051656:KCNQ Potassium Channels; D051657:KCNQ1 Potassium Channel; C496909:KCNQ1 protein, human; C496910:Kcnq1 protein, mouse; D024642:Potassium Channels, Voltage-Gated