Figure 2.

O-GlcNAcylation of PTP1B is increased in insulin resistance. Human HepG2 cells were treated with palmitate (0/0.2/0.4 mmol/L) for 24 h before being stimulated with insulin for 20 min. (A) Proteins were extracted and the phosphorylation of Akt and GSK3β was measured by western blot analysis; (B) O-GlcNAcylation of total cell lysate was analyzed; (C) O-GlcNAcylation of PTP1B was evaluated by immunoprecipitation followed by western blot analysis; (D) mice insulin resistance model and glucose tolerance test; (E) hepatic tissues were obtained from three groups of mice fed a normal or a high fat diet, respectively. O-GlcNAcylation of PTP1B and expression of OGT were measured. Similar results were obtained in two other experiments. (n = 3, * p < 0.05, significantly different from respective controls).