Abstract
Purpose :
Coloboma is a sight-threatening ocular malformation caused by the failure of the optic fissure (OF) closure during development, and is generally related to other ocular abnormalities such as microphthalmia or anophthalmia. The mechanisms underlying optic fissure closure are poorly understood. Due to the direct involvement of the retinal progenitor cells surrounding the OF, we hypothesize that the genes specifically expressed in this area are critical for the OF closure. Thus, in this study we combined microarray, histology and animal model to explore the transcriptome of retinal progenitor cells lining along the OF.
Methods :
We used laser-assisted micro-dissection to collect retinal progenitor cells surrounding the OF, as well as those in the nasal and temporal retina in E11.5 mouse embryos, and used microarray to compare the transcriptomes of different groups of cells. We then performed in situ hybridization (ISH) to verify the microarray results. Finally, we used antisense morpholino oligonucleotides (MOs) to knockdown interested genes in zebrafish embryos to study the functions of these genes in eye development.
Results :
The transcriptome of retinal progenitor cells surrounding the OF was dramatically different from that of retinal progenitor cells inside of the retina. Among the differentially expressed genes, 1131 were dramatically upregulated, 660 downregulated. We chose the top 50 differentially expressed genes, and used ISH to verify and further analyze their retinal tissue expression. The ISH results confirmed specific OF expression of 17 genes; 7 genes were actually expressed in migrating peri-ocular mesenchymal cells; 1 gene was enriched in dorsal retina; and the expression of the rest genes were too weak to be detected. Finally, we picked one gene-Shootin1, and used zebrafish to study its function during OF closure. Knocking down shootin1 by morpholinos resulted in coloboma formation in 88.7% injected fishes, and most of them also developed microphthalmia.
Conclusions :
The retinal progenitor cells surrounding the closing OF express distinct transcriptomes compared to other retinal areas. The OF specific genes play critical roles in regulating the process of the OF closure.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.