Following injury, the embryonic chicken has the capacity to regenerate a neural retina via reprogramming of cells of the retinal pigment epithelium (RPE). After surgical removal of the retina, the injured RPE cells initially respond to injury by dedifferentiating to a more plastic state. However, in order to drive RPE to complete the regeneration process, exogenous Fibroblast Growth Factor 2 (FGF2) must be supplied to RPE to allow for complete reprogramming to retina cells. Importantly, this reprogramming can only occur between days 3.5-4.5 of embryonic development (E3.5-E4.5); at E5 and beyond the RPE is no longer able to regenerate. This project aims to uncover the mechanisms underlying the decline of regenerative potential in chick RPE. We hypothesize that E4 RPE responds to injury and FGF2 by activating neurogenic programs, whereas E5 RPE fails to activate key regenerative genes.
To explore this question, we performed RNA sequencing on chicken RPE collected from various conditions at E4 and E5 to create gene expression profiles. These conditions include: uninjured RPE, RPE 6 hours following retina removal, and RPE 6 hours following retina removal with FGF2 treatment. First, we analyzed the intrinsic differences between uninjured E4 and E5 RPE to discern baseline differences in gene expression during development. Next, we looked for genes regulated differently by FGF2 at E4 and E5. From this, we identified 6 candidate genes that may underlie the difference in regenerative outcome at E4 and E5. Future studies, such as overexpression of these genes at late developmental stages, could unlock the regenerative potential of mature RPE, and help to develop therapies for retinal diseases. The skills gained from my work in the Del Rio-Tsonis Lab will prove instrumental next year as I begin my PhD and throughout my future career as a research scientist.
Author: Emily Van Zeeland
Faculty Advisor: Dr. Katia Del Rio-Tsonis, Department of Biology
Graduate Student Advisor: Jared Tangeman, Department of Biology