The septate junction protein caspr is required for structural support and retention of KCNQ4 at calyceal synapses of vestibular hair cells

Aurea D. Sousa, Leonardo R. Andrade, Felipe T. Salles, Anilkumar M. Pillai, Elizabeth D. Buttermore, Manzoor A. Bhat, Bechara Kachar

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

The afferent innervation contacting the type I hair cells of the vestibular sensory epithelia form distinct calyceal synapses. The apposed presynaptic and postsynaptic membranes at this large area of synaptic contact are kept at a remarkably regular distance. Here, we show by freeze-fracture electron microscopy that a patterned alignment of proteins at the calyceal membrane resembles a type of intercellular junction that is rare in vertebrates, the septate junction (SJ). We found that a core molecular component of SJs, Caspr, colocalizes with the K + channel KCNQ4 at the postsynaptic membranes of these calyceal synapses. Immunolabeling and ultrastructural analyses of Caspr knock-out mice reveal that, in the absence of Caspr, the separation between the membranes of the hair cells and the afferent neurons is conspicuously irregular and often increased by an order of magnitude. In these mutants, KCNQ4 fails to cluster at the postsynaptic membrane and appears diffused along the entire calyceal membrane. Our results indicate that a septate-like junction provides structural support to calyceal synaptic contact with the vestibular hair cell and that Caspr is required for the recruitment or retention of KCNQ4 at these synapses.

Original languageEnglish (US)
Pages (from-to)3103-3108
Number of pages6
JournalJournal of Neuroscience
Volume29
Issue number10
DOIs
StatePublished - Mar 11 2009
Externally publishedYes

ASJC Scopus subject areas

  • Neuroscience(all)

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