Tectorins crosslink type II collagen fibrils and connect the tectorial membrane to the spiral limbus

Leonardo R. Andrade, Felipe T. Salles, M'hamed Grati, Uri Manor, Bechara Kachar

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

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 β 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 β-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. ±. 1.5. nm, width), resembling another collagen type protein, or chains of globular elements (15. ±. 3.2. nm, 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 β-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.

Original languageEnglish (US)
JournalJournal of Structural Biology
DOIs
StateAccepted/In press - Jan 6 2016
Externally publishedYes

Keywords

  • Electron microscopy
  • Extracellular matrix
  • Immunogold-labeling
  • Tectorial membrane
  • Tectorins

ASJC Scopus subject areas

  • Structural Biology

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