Nutrient-Driven O-GlcNAcylation Controls DNA Damage Repair Signaling and Stem/Progenitor Cell Homeostasis

Stem/progenitor cells exhibit high proliferation rates, elevated nutrient uptake, altered metabolic flux, and stress-induced genome instability. O-GlcNAcylation is an essential post-translational modification mediated by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), which act in a nutrient- and stress-responsive manner. The precise role of O-GlcNAc in adult stem cells and the relationship between O-GlcNAc and the DNA damage response (DDR) is poorly understood. Here, we show that hyper-O-GlcNacylation leads to elevated insulin signaling, hyperproliferation, and DDR activation that mimic the glucose- and oxidative-stress-induced response. We discover a feedback mechanism involving key downstream effectors of DDR, ATM, ATR, and CHK1/2 that regulates OGT stability to promote O-GlcNAcylation and elevate DDR. This O-GlcNAc-dependent regulatory pathway is critical for maintaining gut homeostasis in Drosophila and the DDR in mouse embryonic stem cells (ESCs) and mouse embryonic fibroblasts (MEFs). Our findings reveal a conserved mechanistic link among O-GlcNAc cycling, stem cell self-renewal, and DDR with profound implications for stem-cell-derived diseases including cancer. [Display omitted] •Stress induces proliferation, O-GlcNAcylation, and DDR in ISCs/EBs of Drosophila•Elevating O-GlcNAcylation promotes proliferation and DDR in the absence of stress•OGT depletion prevents stress-induced proliferation and DDR in ISCs/EBs•OGT is stabilized by DDR effector CHK1/2 in ISC/EB, a pathway conserved in mammals Na et al. show that stress induces proliferation, DNA damage response (DDR), and O-GlcNAc levels in stem/progenitor cells. Higher O-GlcNAc levels directly induce proliferation and DDR. These data reveal an unexpected conserved autoregulatory loop, wherein the downstream DDR kinases CHK1/2 stabilize OGT, augmenting O-GlcNAcylation and further promoting the DDR pathway.