PHOSPHO1 Suppresses Ferroptosis in Retinal Pigment Epithelial Cells by Reducing the Levels of Phosphatidylethanolamine Molecular Species

Iron-induced lipid peroxidation of phosphatidylethanolamine (PE) species is a key driver of ferroptosis in retinal pigment epithelial (RPE) cells, a process closely associated with age-related macular degeneration (AMD). The previous studies have demonstrated that induced retinal pigment epithelial (iRPE) cells generated by transcription factor-mediated reprogramming exhibit superior therapeutic efficacy in treating AMD. In this study, it is found that these iRPE cells are resistant to ferroptosis and further identified phosphoethanolamine/phosphocholine phosphatase 1 (PHOSPHO1) as a critical regulator underlying ferroptosis resistance. Mechanistically, PHOSPHO1 inhibits ferroptosis through two distinct mechanisms. First, it reduces PE levels in the endoplasmic reticulum, thereby limiting PE-derived lipid peroxidation. Second, it suppresses autophagy and ferritinophagy, leading to a reduction in intracellular free iron accumulation. Experiments using an in vivo rat model confirm that PHOSPHO1 effectively protects RPE cells from ferroptotic damage. These findings highlight PHOSPHO1 as a potential therapeutic target for AMD, providing insights into novel ferroptosis-based intervention strategies.