High Glucose Inhibits O-GlcNAc Transferase Translocation in Early Osteoblast Differentiation by Altering Protein Phosphatase 2A Activity.

Our previous study revealed a link between O-GlcNAc transferase (OGT) localization and protein phosphatase 2A (PP2A) activity in osteoblast. Given the association of PP2A downregulation with osteoblast differentiation, we hypothesized that OGT localization changes during this process. We examined OGT localization in MC3T3-E1 cells undergoing differentiation under normal and high glucose conditions. Changes in PP2A activity were followed by alterations in OGT localization. Organ culture of calvaria revealed similar OGT localization changes in bone-surrounding osteoblasts near the suture area. Furthermore, the levels of O-GlcNAc modification in various proteins including Runt-related transcription factor 2, Osterix, and ATP synthase subunit alpha (ATP5A) were shifted in parallel with OGT translocation. These findings suggest a regulatory role of OGT, under the influence of PP2A, during osteoblast differentiation.