Abstract
Purpose :
Humans are unable to regenerate retinal neurons leading to blinding diseases, in contrast zebrafish exhibit remarkable capacity for regenerating lost neurons throughout life. Multiple studies have defined transcriptomic shifts driving zebrafish retinal regeneration following the death of multiple cells types, but to identify disease-relevant therapeutic strategies it is critical to look at the zebrafish response to loss of discrete retinal cell types. Here, we profiled regeneration-associated transcriptomic shifts over a long time course in zebrafish in response to loss of either rod photoreceptors or bipolar interneurons.
Methods :
The primary method used was bulk-tissue (whole eyes) microarrays conducted on larval zebrafish samples. Our lab has developed transgenic retinal ablation models to kill specific retinal cells and induce a regenerative response. Groups of larvae were collected following the induced ablation (or non-ablated samples for control) of rods or bipolar cells at multiple timepoints throughout regeneration including 0, 8, 16, 24, 32, 40, 48, 60, 72, 96, 144, and 240 hours into induced regeneration. Pathway analysis tools were used to identify patterns characterizing transcriptomic changes at each timepoint along with a particular interest in comparing differentially expressed genes and pathways between the different cell type patterns.
Results :
Throughout our time course we found more cell-type specific transcriptomic changes rather than those shared between the two models. Of the changes that were shared, there was more similarity earlier on following induced cell death (~24h) rather than later (~72h and on). Numerous well-defined pathways were found to be differentially regulated in one model while absent from the other (example: p53 signaling changes more prominent in bipolar cells). We then used the literature to help characterize pathway changes associated with different phases of retinal regeneration including stem cell activation, proliferation, differentiation, and more.
Conclusions :
We successfully identified both shared and cell-type specific regeneration patterns, with the majority leaning toward the latter. This supports the theory that further defining these cell-type specific (fate-biased) responses will be critical in developing more therapeutic strategies to induce regeneration in the mammalian retina.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.