GPX4 ortholog regulates the O-GlcNAc–DDR pathway to preserve intestinal stem cell homeostasis during aging and oxidative stress

Stem cells are essential for tissue maintenance but are highly sensitive to oxidative and metabolic stress. Here, we show that Drosophila Gpxl, the ortholog of mammalian GPX4, preserves intestinal stem cell (ISC) function by coupling nutrient-sensing O-GlcNAcylation to the DNA damage response (DDR) during aging and oxidative stress. In ISCs/enteroblasts of aged or oxidative stressed Drosophila midguts and in aged mouse intestine, expression of Gpxl (Drosophila) and GPX4 (mammals) was increased, coincident with ISC hyperproliferation, elevated O-GlcNAcylation, and enhanced ATM/ATR activity. Under oxidative-stress-induced hyperproliferation, ISCs/EBs-specific Gpxl knockdown attenuated the proliferative response. Moreover, loss of Gpxl suppressed O-GlcNAcase (OGA) knockdown-induced hyperproliferation and dysplasia, suggesting that Gpxl functionally interacts with O-GlcNAc cycling and may exert cell-type-specific actions in stem and differentiated cells. Together, these findings define a Gpxl-O-GlcNAc-DDR axis that integrates lipid-peroxidation defense with nutrient and stress signaling to maintain epithelial homeostasis during aging and oxidative stress. By identifying Gpxl as a required node in O-GlcNAc-dependent proliferative programs, our work nominates this axis as a tractable therapeutic target for age-associated intestinal dysfunction and neoplastic progression.