Abstract
Purpose :
To explore the retinal proteomes at times after partial optic nerve (pONT) injury and characterize the protein expression at the regions showing primary and secondary retinal ganglion cell (RGC) loss.
Methods :
Unilateral pONT was performed on the temporal side of the optic nerve in adult Wistar rats. The RGC density in the retina at 1, 4 and 8 weeks after pONT was topographically quantified. Temporal and nasal retinal samples were collected separately from the eyes after pONT and soluble proteins (n=4; 3 technical replicates) were subjected to profiling with a high resolution hybrid quadrupole time-of-flight MS running on label-free SWATHTM acquisition (SCIEX). An information dependent acquisition ion library was generated from all individual biological replicates for peptides quantification using ProteinPilot 5.0 and OneOmics cloud suite (SCIEX). To examine the pattern change, localization of significantly regulated proteins (P<0.05; FC >1.4 or <0.7) for at least 2 time points was examined by immunohistochemistry.
Results :
More rapid RGC loss was observed in temporal quadrant (primary RGC degeneration) up to 8 weeks after pONT than nasal quadrant (secondary RGC degeneration). Combined proteome analysis detected a total of 1987 proteins with FDR<1% in all biological and technical replicates. Compared to nasal retina, 5, 11 and 32 differentially expressed proteins were detected in temporal retina at 1, 4, and 8 weeks respectively. In temporal quadrant, gamma-synuclein was down-regulated at 1 and 4 weeks while glial fibrillary acidic protein (GFAP) and purkinje cell protein 2 (PCP2) were significantly regulated at 4 and 8 weeks. Immunolocalization of gamma-synuclein indicated the thinning of nerve fiber layer in both temporal and nasal quadrant in a timely manner. Bipolar cell somas and terminals expressed PCP2. After pONT, the location of PCP2 labeled terminals shifted closer to RGC bodies. Double labeling of GFAP and S100B demonstrated an increasing GFAP expression in both astrocytes and Muller cells in temporal quadrant after pONT but in a smaller extent in nasal quadrant.
Conclusions :
The finding demonstrated temporal changes of astrocytes, Muller cells and bipolar cells in parallel with the progression of RGC loss suggesting the involvement of multiple cell types during the propagation of RGC degeneration.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.