Investigating the Role of Cellular Polarity in the Causation of Superior Coloboma

• Author / Creator

  Wilson, Melissa

• Ocular coloboma is a congenital disorder that presents as an ocular malformation in the inferior aspect of the eye and may result in blindness. Recently, our lab characterized a novel disorder, superior coloboma, which presents as a coloboma affecting the superior portion of the eye. We discovered a transient groove in the superior eye during development, termed the superior ocular sulcus (SOS), and hypothesized that superior coloboma results from failed closure of the SOS. Research in our lab has focused on identifying genetic factors that regulate closure of the SOS. We performed whole exome sequencing on five superior coloboma patients to identify potentially disease causing variants that result in failed SOS closure. After analysing variant data, several variants were found in genes involved in planar cell polarity (PCP). Through the course of the current project, evidence was collected to support the hypothesis that PCP is required during eye development to ensure proper timing of SOS closure. Through MO knockdown of the PCP core components, scrib and vangl2, and use of fish carrying a loss of function vangl2 allele, significant SOS closure delays were observed in zebrafish embryos. The Wnt receptor, Fzd4, was also investigated through MO knockdown and morphant embryos were not found to have SOS closure delays, suggesting that Fzd4 does not regulate PCP during eye development. Likewise, the apicobasal component, Shroom3, was investigated in regulation of SOS closure but no significant closure delays were observed in morphant embryos. To investigate the mechanism of PCP-related SOS closure defects, GFP-tagged Prickle was used to indicate planar polarization in live and fixed embryos, with the intent of determining if and when cells within the eye field, optic vesicle and optic cup are planar polarized. While initial results of this experiment are promising, further testing is necessary to determine the dynamics of planar polarization in ocular development. Overall, the research outlined in this work provides a foundation for future studies investigating the role of cellular polarity in ocular development and causation of superior coloboma.

• Subjects / Keywords

  • Coloboma
  • Eye development
  • Planar cell polarity

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-5ar8-n745

• License

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