The nuclear receptor REV-ERBα protects retinal pigment epithelium from sodium iodate-induced damage in mice

Abstract

Purpose : Retinal pigment epithelium (RPE) atrophy is observed in patients with dry form of age-related macular degeneration (AMD), which often causes blindness in the elderly. Chronic oxidative stress during aging is one of the major factors contributing to RPE damage. Here we investigated the role of the nuclear receptor REV-ERBα, a transcriptional regulator of oxidative stress, in RPE health using a sodium iodate (NaIO₃)-induced mouse model of RPE damage with both genetic and pharmacological approaches.

Methods : REV-ERBα deficient (Rev-erbα^-/-) mice and wild type (WT) controls (n=5/group) were injected with NaIO₃ intravenously at 8-week old. In addition, C57BL/6J mice were administrated with NaIO₃ at 8-week old and followed by intraperitoneal injection of REV-ERBα agonist SR9009 or vehicle (n=10/group). RPE damage and retinal toxicity were monitored by fundus imaging and optical coherence tomography (OCT) at day 0, 3, 7 or 14 post injection, and by immunostaining of RPE/choroid flat mounts and cross-sections. RNA and protein expression of REV-ERBα target genes including antioxidant regulators and enzymes was examined in Rev-erbα^-/- vs. WT RPE, and in SR9009 vs. control mouse RPE. Chromatin immunoprecipitation (ChIP) assays were performed to evaluate potential target genes of REV-ERBα.

Results : Rev-erbα^-/- mice exhibited larger RPE lesion area (~3 fold, p< 0.01) in fundus imaging with NaIO₃ injection, and severer structural disturbance of the RPE and retinal layers in OCT, compared with WT mice. H & E staining of eye cross-sections and immunostaining of F-actin in RPE/choroid flat mounts also showed worse RPE disruption in Rev-erbα^-/- vs. WT mice. REV-ERBα agonist SR9009 protected C57BL6/J mice with significantly less RPE lesion area in fundus imaging (p< 0.05), and less apoptotic RPE cells by TUNEL staining (p< 0.01). RNA and protein expression of antioxidant genes, such as Nrf2, SOD1 and SOD2 were substantially decreased in Rev-erbα^{-/ -} vs. WT RPE, and increased in RPE of REV-ERBα agonist SR9009 treated mice vs. controls. ChIP assay identified Nrf2 as a direct transcriptional target of REV-ERBα.

Conclusions : Our findings suggest that REV-ERBα regulates RPE damage through modulating Nrf2, a master regulator of oxidative defense system. Pharmacological activation of REV-ERBα protects RPE from oxidative damage and can thus represent a potential target for developing dry AMD therapeutics.

This is a 2020 ARVO Annual Meeting abstract.