Glutaredoxin 2 (Grx2) protects the retina from light-induced photoreceptor damage via regulating the endothelin receptor B (Ednrb) pathway

1.Purpose : Glutaredoxin 2 (Grx2) is a glutathione-dependent oxidoreductase which is known to reduce S-glutathionylated proteins. In a previous study, we have found that Grx2 could protect the retina from light-induced retinal degeneration. However, the molecular mechanisms that coordinate thiol-repair processes and cell survival systems in the damaged retina remain largely unknown. To better understand the protective effects of Grx2 in the retina, our study was thus extended to analyze the full transcriptome changes of the retinal tissue in light-exposed Grx2 knockout (KO) mice. 2.Methods : Wild type (WT) and Grx2 KO mice were exposed to white light at 23,000 lux for 1 hour after dark adaptation for 10 hours. The retinal damage was confirmed by the electroretinogram (ERG) recording and spectral domain optical coherence tomography (SD-OCT) measurement. Protein glutathionylation level was evaluated by Western Blot. We then compared the full transcriptome of the retinal tissue in WT and Grx2 KO mice using transcriptome shotgun sequencing (RNA-seq). The gene network was analyzed using DESeq2 pathway analysis software, and real-time PCR and Western Blot further confirmed the selected genes of interest. 3.Results : Light-exposed Grx2 KO mice showed compromised visual function as indicated by severe loss of both a- and b-wave amplitudes and the thinning of the outer nuclear layer (ONL). Protein glutathionylation level was elevated in light-exposed Grx2 KO mice. We identified thousands of genes with statistically significant expression changes in light-exposed Grx2 KO mice and classified them into cellular processes and molecular pathways. Among these pathways, many genes that are related to complement activation, inflammation, and cell survival system were significantly upregulated. These genes include Bcl-3 and Fgf2 in NF-KappaB family pathway, C4b in classical activation pathway, Jak3 and STAT3 in JAK-STAT signaling pathway, Cdkn1a in DNA damage response pathway, Edn2 and Ednrb in endothelin 2 signaling pathway. 4.Conclusions : Collectively, our results suggest that Grx2 could protect the retina from light-induced retinal degeneration. Grx2 plays an important role in regulating light-induced retinal inflammation which may be associated with its ability to repair S-glutathionylated substrates.