June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
Wrb functions in a TRC40-dependent pathway required for zebrafish photoreceptor ribbon synapse function
Author Affiliations & Notes
  • Lauren Lee Daniele
    Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH
    Centre for Research in Neuroscience, McGill University, Montreal, QC, Canada
  • Farida Emran
    Centre for Research in Neuroscience, McGill University, Montreal, QC, Canada
  • Glenn Lobo
    Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH
  • Robert Gaivin
    Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH
  • Brian D Perkins
    Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, OH
  • Footnotes
    Commercial Relationships Lauren Daniele, None; Farida Emran, None; Glenn Lobo, None; Robert Gaivin, None; Brian Perkins, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 4372. doi:https://doi.org/
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Lauren Lee Daniele, Farida Emran, Glenn Lobo, Robert Gaivin, Brian D Perkins; Wrb functions in a TRC40-dependent pathway required for zebrafish photoreceptor ribbon synapse function. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4372. doi: https://doi.org/.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Purpose: Ribbon synapses of sensory neurons are specialized for graded and sustained glutamate release, with release rates dynamically adjusting to changing stimulus intensity. While the molecular specializations required for transmitter release at ribbon synapses have been studied extensively, the mechanisms for their biosynthesis, trafficking and assembly remain poorly understood. The goal of this study was to investigate the role of the Wrb protein in ribbon synapse function. Wrb is required for the post-translational insertion of tail - anchored membrane proteins via the transmembrane domain recognition complex (TRC) pathway. Zebrafish wrb mutants show defects in visual and mechanosensory function, and ribbon synapse architecture, suggesting a role for the TRC pathway in ribbon synapse function.

Methods: Electroretinography (ERG), optokinetic response measurements (OKR), immunohistochemistry and electron microscopy analyses were employed to assess ribbon synapse function, protein expression, and ultrastructure in 5 day old zebrafish larvae. Expression of wrb was investigated with real-time qRT-PCR and in-situ hybridization.

Results: In wrb mutants, OKR saccades were infrequent and contrast response functions were flat. ERG b-wave amplitudes were reduced in mutants, while a-waves were unaffected, indicating defective synaptic transmission between photoreceptors and bipolar cels. Bipolar cells of mutants made fewer projections into cone pedicles and synaptic proteins SV2 and ribeye were partially mislocalized in mutant photoreceptors. Wrb is expressed throughout the CNS and Wrb localized to photoreceptor ER and synapses. Morpholino knockdown of TRC40, a key TRC pathway member, resulted in selective impairments similar to wrb mutants, including reduced OKR contrast sensitivity. Overexpression of wrb fully restored contrast sensitivity in mutants, while overexpression of mutant wrbR73A, which cannot bind TRC40, did not.

Conclusions: Wrb and TRC40 are required for synaptic transmission between photoreceptors and bipolar cells, indicating that TA protein insertion by the TRC pathway is a critical step in ribbon synapse assembly and function

×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×