Deletion of Shank1 Has Minimal Effects on the Molecular Composition and Function of Glutamatergic Afferent Postsynapses in the Mouse Inner Ear

Authors

Jeremy P. Braude, University of North Carolina - Wilmington
Sarath Vijayakumar, University of Nebraska - LincolnFollow
Katherine Baumgarner, University of North Carolina - Wilmington
Rebecca Laurine, University of North Carolina - Wilmington
Timothy A. Jones, University of Nebraska - LincolnFollow
Sherri M. Jones, University of Nebraska - LincolnFollow
Sonya J. Pyott, University Medical Center Groningen

Document Type

Article

Date of this Version

3-2015

Citation

Hearing Research (March 2015) 321: 52-64. DOI: 10.1016/j.heares.2015.01.008.

Comments

Copyright 2015, Elsevier. Used by permission.

Abstract

Abstract

Shank proteins (1-3) are considered the master organizers of glutamatergic postsynaptic densities in the central nervous system, and the genetic deletion of either Shank1, 2, or 3 results in altered composition, form, and strength of glutamatergic postsynapses. To investigate the contribution of Shank proteins to glutamatergic afferent synapses of the inner ear and especially cochlea, we used immunofluorescence and quantitative real time PCR to determine the expression of Shank1, 2, and 3 in the cochlea. Because we found evidence for expression of Shank1 but not 2 and 3, we investigated the morphology, composition, and function of afferent postsynaptic densities from defined tonotopic regions in the cochlea of Shank1(-/-) mice. Using immunofluorescence, we identified subtle changes in the morphology and composition (but not number and localization) of cochlear afferent postsynaptic densities at the lower frequency region (8 kHz) in Shank1(-/-) mice compared to Shank1(+/+) littermates. However, we detected no differences in auditory brainstem responses at matching or higher frequencies. We also identified Shank1 in the vestibular afferent postsynaptic densities, but detected no differences in vestibular sensory evoked potentials in Shank1(-/-) mice compared to Shank1(+/+) littermates. This work suggests that Shank proteins play a different role in the development and maintenance of glutamatergic afferent synapses in the inner ear compared to the central nervous system.