Type IX collagen knock-out mouse shows progressive hearing loss.
Type IX collagen is one of the important components, together with type II, V, and XI collagens, in the tectorial membrane of the organ of Corti. To confirm the significance of type IX collagen for normal hearing, we assessed the detailed morphological and electrophysiological features of type IX collagen knock-out mice, which have recently been reported as a deafness model. Through assessment by auditory brainstem response (ABR), knock-out mice were shown to have progressive hearing loss. At the light microscopic level, the tectorial membrane of knock-out mice was found to be abnormal in shape. These morphological changes started in the basal turn and were progressive toward the apical turn. Electron microscopy confirmed disturbance of organization of the collagen fibrils. These results suggest that mutations in type IX collagen genes may lead to abnormal integrity of collagen fibers in the tectorial membrane.
Suzuki
Nobuyoshi
N
Department of Otorhinolaryngology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan.
Asamura
Kenji
K
Kikuchi
Yasutake
Y
Takumi
Yutaka
Y
Abe
Satoko
S
Imamura
Yasutada
Y
Hayashi
Toshihiko
T
Aszodi
Attila
A
Fässler
Reinhard
R
Usami
Shin-ichi
S
D000161:Acoustic Stimulation / Q000379:methods; D000818:Animals; D001309:Auditory Threshold / Q000502:physiology; D001933:Brain Stem / Q000503:physiopathology; D024081:Collagen Type IX / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D018450:Disease Progression; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D034381:Hearing Loss / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout / Q000502:physiology*; D046529:Microscopy, Electron, Transmission / Q000379:methods; D013680:Tectorial Membrane / Q000473:pathology / Q000648:ultrastructure; D013997:Time Factors
D024081:Collagen Type IX