A novel protein encoded by hsa_circ_0068626 contributes to age-related cataract via the p62/Keap1/Nrf2 signaling pathway-mediated ferroptosis

This study investigates whether circular RNAs (circRNAs) modulate ferroptosis in lens epithelial cells (LECs) during age-related cataract (ARC) pathogenesis via novel encoded proteins. Initial circRNA-sequencing identified hsa_circ_0068626 (circTFRC) as significantly upregulated in ARC, predominantly localized to the cytoplasm through nuclear-cytoplasmic fractionation and fluorescence in situ hybridization (FISH). Functional assays revealed that circTFRC depletion impaired LECs proliferation and viability, while overexpression exacerbated ferroptosis, evidenced by elevated intracellular reactive oxygen species (ROS) and Fe²⁺ level via fluorescence probes and flow cytometry. Mechanistically, circTFRC harbored an open reading frame (ORF) and internal ribosome entry site (IRES), enabling translation of the circTFRC-236aa protein, confirmed by polysome profiling and custom antibody detection. Western blot analyses demonstrated that circTFRC-236aa activated the p62/Keap1/Nrf2 axis, correlating with GPX4 suppression and ferroptosis. Transmission electron microscopy further visualized mitochondrial morphological abnormalities consistent with ferroptotic stress. Collectively, these findings establish circTFRC as a pro-ferroptotic regulator in ARC, where its encoded circTFRC-236aa drives pathological progression via p62/Keap1/Nrf2 pathway activation, offering a novel therapeutic target for mitigating ARC-associated LECs damage.