title: Expression of cochlin in the vestibular organ of rats.
abstract: The COCH gene mutated in autosomal dominant sensorineural deafness (DFNA9) encodes cochlin, a major constituent of the inner ear extracellular matrix. Cochlin constitutes 70% of the inner ear protein and cochlin isoforms can be classified into three subgroups, p63s, p44s and p40s. Symptoms of some DFNA9 patients are consistent with those of Ménière's disease. Here, we report the expression of cochlin in the vestibular organ of rats using isoform-specific antibodies that recognize all three isoforms. Cochlin is highly expressed in the stromata of the maculae of otolithic organs and cristae of semicircular canals, and in the channels in the bony labyrinth that transmit the dendritic innervation to the cristae and maculae. Cochlin cannot be detected in the sensory cells, dark cells, nor in the acellular structures, otolithic membrane or in the cupula. These findings support the theory that deposition of acidophilic substance in the inner ear caused by mutation of cochlin can induce a secondary retrograde dendritic degeneration of the vestibular nerves.
authors.affiliation: Department of Otorhinolaryngology, Nippon Medical School, Tokyo, Japan. tikezono@nms.ac.jp
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ikezono
authors.forename: Susumu
authors.initials: S
authors.lastname: Shindo
authors.forename: Masamichi
authors.initials: M
authors.lastname: Ishizaki
authors.forename: Lishu
authors.initials: L
authors.lastname: Li
authors.forename: Shunichi
authors.initials: S
authors.lastname: Tomiyama
authors.forename: Masaya
authors.initials: M
authors.lastname: Takumida
authors.forename: Ruby
authors.initials: R
authors.lastname: Pawankar
authors.forename: Atsushi
authors.initials: A
authors.lastname: Watanabe
authors.forename: Akihiko
authors.initials: A
authors.lastname: Saito
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yagi
mesh_terms: D000818:Animals; D003638:Deafness / Q000235:genetics* / Q000378:metabolism; D016326:Extracellular Matrix Proteins; D015870:Gene Expression; D007150:Immunohistochemistry; D008575:Meniere Disease / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D020033:Protein Isoforms; D011506:Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D014722:Vestibule, Labyrinth / Q000378:metabolism*
chemical_list: C110668:COCH protein, human; D016326:Extracellular Matrix Proteins; D020033:Protein Isoforms; D011506:Proteins