Abstract
Purpose :
Lens crystallins and lipids have extended lifespans with minimal turnover within the lens. The prolonged existence of these proteins and lipids makes them more prone to damage from oxidation. Age-related increases in lipid peroxidation have been observed in both human and mouse lenses. However, the precise role of lipid peroxidation in cataractogenesis remains unclear. In this study, we aim to investigate whether the deletion of lipid peroxidation suppressor GPX4 plays a role in the formation of cataract.
Methods :
Gpx4 was genetically knocked out in human lens epithelial cells (FHL124) using CRISPR-Cas9 technology. Cataracts were evaluated using a slit lamp and darkfield microscopy. The lens epithelial cells were quantified through serial HE sections. Plasma membrane lipid peroxidation was assessed using immunofluorescent staining and lipidomics. Rescue experiments were conducted by treating Gpx4 knockout (KO) mice with liproxstatin-1. Cell viability was determined through a CCK8 assay, while lipid peroxidation was assessed using C11-Bodipy 581/591.
Results :
In Vitro: Deletion of GPX4 in FHL124 cells led to a significant increase in cell membrane lipid oxidation, iron accumulation, and cell death. A lipid peroxidation inhibitor, liproxstatin-1 (Lip-1), was able to effectively rescue the cells from lipid peroxidation-induced cell death. Ex Vivo: RSL3, a potent GPX4 inhibitor, induced lipid oxidation and lens opacity in ex vivo cultured lenses, and could be prevented by (Lip-1). In Vivo: Lens-specific Gpx4 deletion was achieved using MLR10-Cre/Gpx4f/f, resulting in the observation of cataracts in mice at P0. These cataracts progressively worsened during postnatal lens development, eventually leading to microphthalmia in adult Gpx4 KO mice. Cell death was evident in the Gpx4 KO lenses, and further investigations revealed a significant increase in markers associated with ferroptosis rather than apoptosis. Interestingly, administering the ferroptosis inhibitor liproxstatin-1 via intraperitoneal injection before E12.5 effectively alleviated cataract formation in Gpx4 KO mice.
Conclusions :
Our findings highlight the protective role of GPX4 against lipid oxidation, emphasizing that the lack of Gpx4 contributes to the formation of cataracts in mouse lenses. Managing lipid peroxidation emerges as a potential approach for averting the onset of cataracts.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.