Tectorins crosslink type II collagen fibrils and connect the tectorial membrane to the spiral limbus.
J Struct Biol
; 194(2): 139-46, 2016 May.
Article
em En
| MEDLINE
| ID: mdl-26806019
ABSTRACT
All inner ear organs possess extracellular matrix appendices over the sensory epithelia that are crucial for their proper function. The tectorial membrane (TM) is a gelatinous acellular membrane located above the hearing sensory epithelium and is composed mostly of type II collagen, and α and ß tectorins. TM molecules self-assemble in the endolymph fluid environment, interacting medially with the spiral limbus and distally with the outer hair cell stereocilia. Here, we used immunogold labeling in freeze-substituted mouse cochleae to assess the fine localization of both tectorins in distinct TM regions. We observed that the TM adheres to the spiral limbus through a dense thin matrix enriched in α- and ß-tectorin, both likely bound to the membranes of interdental cells. Freeze-etching images revealed that type II collagen fibrils were crosslinked by short thin filaments (4±1.5nm, width), resembling another collagen type protein, or chains of globular elements (15±3.2nm, diameter). Gold-particles for both tectorins also localized adjacent to the type II collagen fibrils, suggesting that these globules might be composed essentially of α- and ß-tectorins. Finally, the presence of gold-particles at the TM lower side suggests that the outer hair cell stereocilia membrane has a molecular partner to tectorins, probably stereocilin, allowing the physical connection between the TM and the organ of Corti.
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MEDLINE
Assunto principal:
Órgão Espiral
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Membrana Tectorial
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Proteínas da Matriz Extracelular
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Colágeno Tipo II
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Proteínas de Membrana
Limite:
Animals
Idioma:
En
Ano de publicação:
2016
Tipo de documento:
Article