O-Linked beta-N-Acetylglucosaminylation in Mouse Embryonic Neural Precursor Cells

In neural stem cells (NSCs), glycoconjugates and carbohydrate antigens are known not only to serve as excellent cell surface biomarkers for cellular differentiation and development but also to play important functional roles in determining cell fate. O-linked beta-N-acetylglucosamine (O-GIcNAc), which modifies nuclear and cytoplasmic proteins on the serine and threonine residues, is also expected to play an important regulatory role. It is not known, however, whether O-GIcNAc is expressed in NSCs or what the function of this expression is. In this study, we evaluated the patterns and possible functions of O-GIcNAcylation in mouse embryonic neuroepithelial cells (NECs), which are known to be rich in NSCs. We confirmed the expression of O-GIcNAc transferase, O-GIcNAcase, and several O-GIcNAcylated proteins in NECs. Treatment of NECs with O-GIcNAcase inhibitors, PUGNAc and streptozotocin, induced robust accumulation of O-GIcNAc in NECs and reduction of number of NECs. In O-GIcNAcase inhibitor-treated NECs, the Rasmitogen-activated protein kinase pathway and the phosphatidylinositol 3-kinase-Akt pathway, important for proliferation and survival, respectively, were intact, but caspase-3, an executioner for cell death, was activated. These results suggest the possibility that O-GIcNAc is involved in cell death signaling in NECs. Furthermore, in NECs, we identified an O-GIcNAc-modified protein, Sp1 transcription factor. Our study is the first to evaluate expression and functions of O-GIcNAc in NECs. (C) 2009 wiley-Liss, Inc.