Figure 1.

A schematic model illustrating O‐GlcNAc pathway and influence of glucose and O‐GlcNAcylation on chondrogenic differentiation. Glucose synthesizes UDP‐GlcNAc by HBP. O‐GlcNAc pathway consists of transfer and removal of O‐GlcNAc by OGT and OGA. Glucose decreases PKC activity with O‐GlcNAcylation by HBP, thus down‐regulating the expression of TGFβRII in cell pellets. The reduced TGFβRII expression results in decreased TGF‐β signalling upon the activation of TGF‐β ligand, further leading to reduced chondrogenesis.