Functional Roles of O-Glcnac in Cell Signaling

Many nuclear and cytosolic proteins are modified with O-linked β-N-acetylglucosamine (O-GlcNAc) at serine or threonine residues. This O-GlcNAcylation is a dynamic posttranslational modification similar to phosphorylation. In addition, O-GlcNAcylation and phosphorylation have a reciprocal relationship to modulate the function of proteins. There are three types of dynamic interplay between O-GlcNAcylation and phosphorylation. These two modifications occur on same site of the protein or occur on two different sites nearby. Therefore, there is a competitive relationship between O-GlcNAcylation and phosphorylation. The third possibility is these two modifications occur on multiple sites of proteins, and they affect each other or not. In this case, the modification status is changed by cellular signaling. O-GlcNAc modification has vital roles in protein localization, protein degradation, protein stability, transcription, translation, cell cycle regulation, protein-protein interaction, epigenetic regulation, and various diseases including cancer, diabetes, and neurodegenerative diseases. This chapter presents an overview of the function of O-GlcNAc modification in various signaling pathways.