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Glutamate Transporters EAAT4 and EAAT5 Are Expressed in Vestibular Hair Cells and Calyx Endings

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posted on 19.11.2013, 00:00 authored by Antoine Dalet, Jeremie Bonsacquet, Sophie Gaboyard-Niay, Irina Calin-Jageman, Robstein L. Chidavaenzi, Stephanie Venteo, Gilles Desmadryl, Jay M. Goldberg, Anna Lysakowski, Christian Chabbert
Glutamate is the neurotransmitter released from hair cells. Its clearance from the synaptic cleft can shape neurotransmission and prevent excitotoxicity. This may be particularly important in the inner ear and in other sensory organs where there is a continually high rate of neurotransmitter release. In the case of most cochlear and type II vestibular hair cells, clearance involves the diffusion of glutamate to supporting cells, where it is taken up by EAAT1 (GLAST), a glutamate transporter. A similar mechanism cannot work in vestibular type I hair cells as the presence of calyx endings separates supporting cells from hair-cell synapses. Because of this arrangement, it has been conjectured that a glutamate transporter must be present in the type I hair cell, the calyx ending, or both. Using whole-cell patch-clamp recordings, we demonstrate that a glutamateactivated anion current, attributable to a high-affinity glutamate transporter and blocked by DL-TBOA, is expressed in type I, but not in type II hair cells. Molecular investigations reveal that EAAT4 and EAAT5, two glutamate transporters that could underlie the anion current, are expressed in both type I and type II hair cells and in calyx endings. EAAT4 has been thought to be expressed almost exclusively in the cerebellum and EAAT5 in the retina. Our results show that these two transporters have a wider distribution in mice. This is the first demonstration of the presence of transporters in hair cells and provides one of the few examples of EAATs in presynaptic elements.

Funding

This work was supported by the Centre National daˆ’Etudes Spatiales, the French Ministry of Research and New Technologies (grants to AD and JB) and the National Institute on Deafness and Other Communication Disorders (DC2058 to JMG and AL) (http://www.nidcd.nih.gov/Pages/default.aspx, http://www.cnes. fr/web/CNES-fr/6919-cnes-tout-sur-l-espace.php, http://www.enseignementsup-recherche.gouv.fr/).

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Publisher Statement

The original version is available through Public Library of Science at DOI: 10.1371/journal.pone.0046261.© 2012 Dalet et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Citation

Dalet, A. Bonsacquet, J. Gaboyard-Niay, S. Calin-Jageman, I. Chidavaenzi, R. L. Venteo, S. Desmadryl, G. Goldberg, J. M. Lysakowski, A. Chabbert, C..Glutamate Transporters EAAT4 and EAAT5 Are Expressed in Vestibular Hair Cells and Calyx Endings. Plos One. Sep 2012;7(9).

Publisher

Public Library of Science

Language

en_US

issn

1932-6203

Issue date

01/09/2012

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