O-GlcNAcylation Mediates Wnt-stimulated Bone Formation via Rewiring Aerobic Glycolysis in Osteoblast-lineage Cells

As the efficient therapeutic treatment for osteoporosis, Wnt signaling is considered to induce bone formation through aerobic glycolysis. However, the mechanism underlying the regulatory role of Wnt in orchestrating glucose metabolism during osteogenesis remains unclear. O-GlcNAcylation, a dynamic posttranslational modification (PTM) on proteins, controls multiple critical biological processes including gene transcription, translation, and cell fate determination. Here, we report Wnt3a either induces O-GlcNAcylation rapidly via the Ca2+-PKA-Gfat1 axis, or increases it in a Wnt-β-catenin dependent manner during prolonged stimulation. Importantly, O-GlcNAcylation is found indispensable for osteoblastogenesis both in vivo and in vitro. Genetic ablation of O-GlcNAcylation in osteoblast-lineage cells diminishes bone formation and delays bone fracture healing in response to Wnt stimulation. Notably, Wnt3a-induced O-GlcNAcylation enhances aerobic glycolysis by stabilizing PDK1 partially through Serine 174 (S174) site, which consequently facilitates osteogenesis. These findings highlight that O-GlcNAcylation is indispensable in Wnt-induced glucose metabolism during osteogenesis, indicating its potential as a therapeutic target for osteoporosis. For RNA -Seq experiments, ST2 cells were exposed to vehicle, OSMI (20 μM), or rhWnt3a (50ng/ml) for 72 hours prior to obtaining total RNA.