PCYT1A deficiency disturbs fatty acid metabolism and induces ferroptosis in mice retina

Abstract Inherited retinal dystrophies (IRDs) encompass a group of debilitating visual disorders characterized by the progressive degeneration of photoreceptors, ultimately leading to blindness. Among the causes of this condition, mutations in the PCYT1A gene have been identified, which encodes the rate-limiting enzyme responsible for phosphatidylcholine (PC) de novo synthesis within the Kennedy pathway. However, the precise mechanisms underlying the association between PCYT1A mutations and IRDs remain unclear. To address this knowledge gap, we focused on elucidating the functions of PCYT1A in the retina. Initially, we demonstrated that PCYT1A exhibits predominant expression in Müller glia (MG) cells situated in the inner nuclear layer (INL) of the retina. Subsequently, we generated a retina-specific knockout mouse model targeting the Pcyt1a gene (Pcyt1a-RKO or RKO mice) to investigate the molecular mechanisms underlying IRDs caused by PCYT1A mutations. Our findings revealed that the deletion of PCYT1A resulted in retinal degeneration phenotypes, including reduced scotopic electroretinogram (ERG) responses and progressive degeneration of photoreceptor cells, accompanied by loss of cells in the INL. Furthermore, through proteomic and bioinformatics analyses, we observed dysregulated retinal fatty acid metabolism and activation of the ferroptosis signaling pathway in RKO mice. Importantly, we established that PCYT1A deficiency did not lead to an overall reduction in PC synthesis within the retina. Instead, it appeared to disrupting the free fat acid metabolism and ultimately triggering ferroptosis. This study unveils a novel mechanism by which mutations in PCYT1A contribute to the development of IRDs, shedding light on the interplay between fatty acid metabolism and retinal degenerative diseases, and will provide new insights into the treatment of IRDs.