Suppression of ferroptosis by vitamin A or antioxidants is essential for neuronal development

Development of functional neurons is a complex orchestration of several signaling pathways controlling cell proliferation, differentiation, and homeostasis1. However, details about the involved factors are not fully understood. The balance of antioxidants and vitamins is important for neuronal survival, synaptic plasticity, and early neuronal development; thus, we hypothesized that ferroptosis--a lipid peroxidation dependent cell death modality that is inhibited by antioxidanats2,3--needs to be suppressed to gain neurons. Our study shows that removal of antioxidants diminishes neuronal development and laminar organization of cortical organoids. Intriguingly, impaired neuronal development in conditions lacking antioxidants can be fully restored when ferroptosis is specifically inhibited by ferrostatin-1, or neuronal differentiation occurs in the presence of sufficient amounts of vitamin A. Mechanistically, vitamin A activates the heterodimeric nuclear receptor complex Retinoic Acid Receptor (RAR)/Retinoid X Receptor (RXR)4, which upregulates expression of the ferroptosis regulators GPX4, FSP1, GCH1, and ACSL3, amongst others. Therefore, our study reveals that above a certain threshold, vitamin A increases expression of essential cellular gatekeepers of lipid peroxidation. This study uncovers a critical process during early neuronal development, where suppression of ferroptosis by radical-trapping antioxidants or vitamin A is required to obtain maturing neurons and proper laminar organization in cortical organoids.