The number and distribution of AMPA receptor channels containing fast kinetic GluA3 and GluA4 subunits at auditory nerve synapses depend on the target cells

Rubio, María E and Matsui, Ko and Fukazawa, Yugo and Kamasawa, Naomi and Harada, Harumi and Itakura, Makoto and Molnár, Elek and Abe, Manabu and Sakimura, Kenji and Shigemoto, Ryuichi (2017) The number and distribution of AMPA receptor channels containing fast kinetic GluA3 and GluA4 subunits at auditory nerve synapses depend on the target cells. Brain Structure and Function, 222 (8). 3375 -3399. ISSN 1863-2661

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Abstract

The neurotransmitter receptor subtype, number, density, and distribution relative to the location of transmitter release sites are key determinants of signal transmission. AMPA-type ionotropic glutamate receptors (AMPARs) containing GluA3 and GluA4 subunits are prominently expressed in subsets of neurons capable of firing action potentials at high frequencies, such as auditory relay neurons. The auditory nerve (AN) forms glutamatergic synapses on two types of relay neurons, bushy cells (BCs) and fusiform cells (FCs) of the cochlear nucleus. AN-BC and AN-FC synapses have distinct kinetics; thus, we investigated whether the number, density, and localization of GluA3 and GluA4 subunits in these synapses are differentially organized using quantitative freeze-fracture replica immunogold labeling. We identify a positive correlation between the number of AMPARs and the size of AN-BC and AN-FC synapses. Both types of AN synapses have similar numbers of AMPARs; however, the AN-BC have a higher density of AMPARs than AN-FC synapses, because the AN-BC synapses are smaller. A higher number and density of GluA3 subunits are observed at AN-BC synapses, whereas a higher number and density of GluA4 subunits are observed at AN-FC synapses. The intrasynaptic distribution of immunogold labeling revealed that AMPAR subunits, particularly GluA3, are concentrated at the center of the AN-BC synapses. The central distribution of AMPARs is absent in GluA3-knockout mice, and gold particles are evenly distributed along the postsynaptic density. GluA4 gold labeling was homogenously distributed along both synapse types. Thus, GluA3 and GluA4 subunits are distributed at AN synapses in a target-cell-dependent manner.

Item Type: Article
DOI: 10.1007/s00429-017-1408-0
Uncontrolled Keywords: Synapses, electron microscopy, postsynaptic density, ventral cochlear nucleus, bushy cells, fusiform cells, freeze-fracture replica immunolabeling
Subjects: 500 Science > 570 Life sciences; biology > 571 Physiology
Research Group: Shigemoto Group
SWORD Depositor: Sword Import User
Depositing User: Sword Import User
Date Deposited: 12 Dec 2017 13:30
Last Modified: 12 Dec 2017 13:30
URI: https://repository.ist.ac.at/id/eprint/881

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