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Updated: Aug 23, 2025
4-Dimensional Imaging of Zebrafish Optic Cup Morphogenesis
Published on: May 26, 2021
Zfp503/Nlz2 Is Required for RPE Differentiation and Optic Fissure Closure
Elangovan Boobalan1, Amy H Thompson1, Ramakrishna P Alur1
1Pediatric, Developmental & Genetic Ophthalmology Section, Ophthalmic Genetics & Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States.
Purpose:
Uveal coloboma is a congenital eye malformation caused by failure of the optic fissure to close in early human development. Despite significant progress in identifying genes whose regulation is important for executing this closure, mutations are detected in a minority of cases using known gene panels, implying additional genetic complexity. We have previously shown knockdown of znf503 (the ortholog of mouse Zfp503) in zebrafish causes coloboma. Here we characterize Zfp503 knockout (KO) mice and evaluate transcriptomic profiling of mutant versus wild-type (WT) retinal pigment epithelium (RPE)/choroid.
Methods:
Zfp503 KO mice were generated by gene targeting using homologous recombination. Embryos were characterized grossly and histologically. Patterns and level of developmentally relevant proteins/genes were examined with immunostaining/in situ hybridization. The transcriptomic profile of E11.5 KO RPE/choroid was compared to that of WT.
Results:
Zfp503 is dynamically expressed in developing mouse eyes, and loss of its expression results in uveal coloboma. KO embryos exhibit altered mRNA levels and expression patterns of several key transcription factors involved in eye development, including Otx2, Mitf, Pax6, Pax2, Vax1, and Vax2, resulting in a failure to maintain the presumptive RPE, as evidenced by reduced melanin pigmentation and its differentiation into a neural retina-like lineage. Comparison of RNA sequencing data from WT and KO E11.5 embryos demonstrated reduced expression of melanin-related genes and significant overlap with genes known to be dynamically regulated at the optic fissure.
Conclusions:
These results demonstrate a critical role of Zfp503 in maintaining RPE fate and optic fissure closure.
Insights
Zfp503 gene loss causes uveal coloboma in mice by disrupting retinal pigment epithelium fate and optic fissure closure. This study highlights Zfp503
Area of Science:
- Developmental biology
- Ophthalmology
- Genetics
Background:
- Uveal coloboma is a congenital eye malformation.
- Genetic mutations explain only a minority of cases.
- Zfp503 is implicated in zebrafish eye development.
Purpose of the Study:
- Characterize Zfp503 knockout (KO) mice.
- Investigate Zfp503's role in optic fissure closure.
- Analyze transcriptomic changes in mutant RPE/choroid.
Main Methods:
- Generated Zfp503 KO mice via gene targeting.
- Performed histological and molecular analyses.
- Conducted RNA sequencing of E11.5 RPE/choroid.
Main Results:
- Zfp503 loss causes uveal coloboma in mice.
- Altered expression of key eye development transcription factors observed.
- Reduced melanin synthesis and RPE to neural retina lineage switch occurred.
- RNA sequencing revealed downregulated melanin genes and optic fissure-related genes.
Conclusions:
- Zfp503 is critical for maintaining RPE fate.
- Zfp503 plays a vital role in optic fissure closure.
- Identified Zfp503 as a key gene in eye development.
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