Excessive O-GlcNAcylation of proteins suppresses spontaneous cardiogenesis in ES cells.

Increased modification of proteins with O-linked N-acetylglucosamine (O-GlcNAc) has been implicated in the development of diabetic cardiomyopathy. We used the well-characterized ES cells (Nkx2.5GFP knock-in ES cells), to investigate the role of O-GlcNAcylation in cardiomyocyte development. O-GlcNAcylation decreased in differentiating ES cells, as did the expression of O-GlcNAc transferase. Increasing O-GlcNAcylation with glucosamine or by inhibiting N-acetylglucosaminidase (streptozotocin or PUGNAc) decreased the number of cardiomyocyte precursors and cardiac-specific gene expression. On the other hand, decreasing O-GlcNAcylation with an inhibitor of glutamine fructose-6-phosphate amidotransferase (6-diazo-5-oxo-norleucine) increased cardiomyocyte precursors. These results suggest that excessive O-GlcNAcylation impairs cardiac cell differentiation in ES cells.