Reduction of myc-Nkx2.5 protein in cells treated with <i>O</i>-GlcNAcase inhibotirs.

<p>(A) Immunoblotting of myc-Nkx2.5 and <i>O</i>-GlycNAcylated proteins in myc-Nkx2.5-transfected HEK293 cells in the presence or absence of 3 mM streptozotocine (STZ). (B) Graphs showed relative <i>O</i>-GlcNAc (left) and myc-Nkx2.5 (right) levels normalized to the tubulin levels in STZ-treated and untreated cells. <i>O</i>-GlcNAcylation levels were compared in untreated cells <i>vs</i> STZ-treated cells and untreated myc-Nkx2.5 cells <i>vs</i> STZ-treated myc-Nkx2.5 cells. The myc-Nkx2.5 protein levels were compared in untreated myc-Nkx2.5 cells <i>vs</i> STZ-treated myc-Nkx2.5 cells. All values are presented as the mean±standard error of three independent experiments. *<i>p</i><0.05. (C) Immunoblotting analysis of myc-Nkx2.5 and <i>O</i>-GlycNAcylated proteins in myc-Nkx2.5-transduced HEK293 cells in the presence or absence of <i>O</i>-(2-acetamido-2-deoxy-D-glucopyroanosylidene)-amino-<i>N</i>-phenylcarbamate (10 or 100 µM PUGNAC). (D) Graphs showed relative <i>O</i>-GlcNAc (left) and myc-Nkx2.5 (right) levels normalized to the tubulin levels in PUGNAC-treated and untreated cells. The treatment with STZ and PUGNAC significantly increased the <i>O</i>-GlcNAcylation of intracellular proteins, but decreased the myc-Nkx2.5 protein significantly. <i>O</i>-GlcNAcylation levels were compared in untreated myc-Nkx2.5 cells <i>vs</i> PUGNAC-treated myc-Nkx2.5 cells. The myc-Nkx2.5 protein levels were compared in untreated myc-Nkx2.5 cells <i>vs</i> PUGNAC treated myc-Nkx2.5 cells. All values are presented as the mean±standard error of three independent experiments. *<i>p</i><0.05.