L-type voltage-gated calcium channel agonists mitigate hearing loss and modify ribbon synapse morphology in the zebrafish model of usher syndrome type 1

Alaa Koleilat, Joseph A. Dugdale, Trace A. Christenson, Jeffrey L. Bellah, Aaron M. Lambert, Mark A. Masino, Stephen C. Ekker, Lisa A. Schimmenti

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The mariner (myo7aa/) mutant is a zebrafish model for Usher syndrome type 1 (USH1). To further characterize hair cell synaptic elements in myo7aa/ mutants, we focused on the ribbon synapse and evaluated ultrastructure, number and distribution of immunolabeled ribbons, and postsynaptic densities. By transmission electron microscopy, we determined that myo7aa/− zebrafish have fewer glutamatergic vesicles tethered to ribbon synapses, yet maintain a comparable ribbon area. In myo7aa/− hair cells, immunolocalization of Ctbp2 showed fewer ribbon-containing cells in total and an altered distribution of Ctbp2 puncta compared to wild-type hair cells. myo7aa/− mutants have fewer postsynaptic densities - as assessed by MAGUK immunolabeling - compared to wild-type zebrafish. We quantified the circular swimming behavior of myo7aa/− mutant fish and measured a greater turning angle (absolute smooth orientation). It has previously been shown that L-type voltage-gated calcium channels are necessary for ribbon localization and occurrence of postsynaptic density; thus, we hypothesized and observed that L-type voltage-gated calcium channel agonists change behavioral and synaptic phenotypes in myo7aa/− mutants in a drug-specific manner. Our results indicate that treatment with L-type voltage-gated calcium channel agonists alter hair cell synaptic elements and improve behavioral phenotypes of myo7aa/− mutants. Our data support that L-type voltage-gated calcium channel agonists induce morphological changes at the ribbon synapse - in both the number of tethered vesicles and regarding the distribution of Ctbp2 puncta - shift swimming behavior and improve acoustic startle response.

Original languageEnglish (US)
Article numberdmm043885
JournalDMM Disease Models and Mechanisms
Volume13
Issue number11
DOIs
StatePublished - Nov 27 2020

Keywords

  • Hair cell
  • Hearing loss
  • Myo7aa
  • Ribbon synapse
  • Zebrafish

ASJC Scopus subject areas

  • Neuroscience (miscellaneous)
  • Medicine (miscellaneous)
  • Immunology and Microbiology (miscellaneous)
  • Biochemistry, Genetics and Molecular Biology(all)

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