July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Adhesion Dynamics During Choroid Fissure Closure in a Developing Zebrafish Eye
Author Affiliations & Notes
  • Andrea James
    Biology, University of Northern Colorado, Greeley, Colorado, United States
  • Zvi Murry
    Biology, University of Northern Colorado, Greeley, Colorado, United States
  • Jessica Pardue
    Biology, University of Northern Colorado, Greeley, Colorado, United States
  • Taryn Likes
    Biology, University of Northern Colorado, Greeley, Colorado, United States
  • Matthew Meyer
    Shared Equipment Authority, Rice University, Houston, Texas, United States
  • Footnotes
    Commercial Relationships   Andrea James, None; Zvi Murry, None; Jessica Pardue, None; Taryn Likes, None; Matthew Meyer, None
  • Footnotes
    Support  Knight Templar Career Starter Grant
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 6007. doi:
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      Andrea James, Zvi Murry, Jessica Pardue, Taryn Likes, Matthew Meyer; Adhesion Dynamics During Choroid Fissure Closure in a Developing Zebrafish Eye. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6007.

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

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Abstract

Purpose : A critical aspect of vertebrate eye development is closure of the transient choroid fissure (CF). Defects in CF closure (CFC) result in colobomas, which contribute to 3-11% of childhood blindness worldwide. Despite the growing number of mutated loci associated with colobomas, we have a limited understanding of the cell biological underpinnings of CFC. Here we utilize zebrafish embryos to identify required molecular signaling for proper CFC. Previously, we demonstrated a transient β-catenin/actin fusion seam within the fusing CF indicating a role for cadherin based adherens junction (AJ) formation. We hypothesize Rac regulates membrane dynamics in CF edge cells inducing N-cadherin interactions between CF sides initiating temporary seal in the central CF that progressing bi-derectionally.

Methods : Rx3:GFP zebrafish in vivo confocal microscopy was quatified using ImageJ to deteremine distance between CF sides. To determine spatiotemporal localization for membrane protrusion regulators and AJ formation during CFC, wildtype zebrafish embryos were fixed throughout CFC timepoints, cryosectioned and confocal immunofluorescence imaging of Rac & N-cadherin collected. WT zebrafish were prepared and sectioned for TEM analysis to verify the formation of AJs and/or tight junctions (TJs) during CFC.

Results : in vivo analysis demonstrates a processive closure along the distal/proximal axis of the CF. As the apposed sides of the CF reduce the distance between two sides, a dilation of the CF occurrs prior to final closure. Additionally, we noted both Rac & N-cahderin are highly localized at membranes 1-3 cells from the edges of the CF when compared to neuroretina. Rac and N-cadherin localization within edge cells drastically decreases upon fusion. Furthermore, TEM analysis demonstrates classical AJ formation along the entire CF during fusion but also along the entirety of edge cells however TJs were not observed.

Conclusions : Our data indicate a highly dynamic transient molecular fusion event for CFC. Our data demonstrate differences along the proximal/distal axis and dilation events after closure initiation indicating a possibility of cells migrating within the CF aiding fusion and/or a requirement for proper timing of adhesioni nteractions. Our data support a model in which membrane protrusions increase the area in which cell adhesion proteins interact to form a mature AJs but do not mature further to form TJs.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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