Abstract
Purpose :
During glaucoma, retinal ganglion cell (RGC) axons are damaged and this causes the RGCs to die, ultimately resulting in the irreversible loss of visual function. Currently, there are no FDA-approved drugs or therapies to protect RGCs from death in glaucoma. Unlike in mammals, zebrafish maintain most RGCs after optic nerve injury; however, the molecular underpinnings of RGC neuroprotection are unknown. Here, we aim to identify neuroprotective factors in adult zebrafish RGCs after injury and to determine which genes/pathways are required for the survival of RGCs after optic nerve transection.
Methods :
isl2b: GFP transgenic zebrafish, in which a subset of RGCs are labeled by the transgene, were utilized at ~ 3 months (equal number of male and female animals). Animals underwent an optic nerve transection surgery, performed by the same person on the left eye, while the right eye of the same fish went through a mock surgery as the control. To quantify RGC survival after transection, retinal flat mounts were made and imaged using confocal microscopy at 1,3,7 and 14 days post-injury(dpi) and RGC survival over time were quantified using ImageJ software. Retinae were dissociated and RGCs were sorted by fluorescence-activated cell sorting and collected at 6,12 and 24 hours post-injury(hpi). RNA-Seq was performed, in biological triplicate, and gene expression changes after injury were quantified.
Results :
After injury, RGC survival was: 94.44 ± 5.45% (1dpi); 92.52 ± 3.54% (3dpi) and 76.35 ± 2.58% (7dpi), with levels returning to 98.71 ± 4.82% at 14dpi,and achived98.71 ± 4.82%. Preliminary analyses of RNA-seq data identify several candidate genes and pathways that are involved in RGC survival after optic nerve injury, and these include pathways functioning in transcriptional regulation, modulation of inflammatory responses and cell-cell signaling.
Conclusions :
Zebrafish maintain most RGCs after optic nerve injury. Candidate factors involved in RGC survival have been identified and these could represent novel neuroprotective factors to protect RGCs from death in glaucoma.
This is a 2020 ARVO Annual Meeting abstract.