Institute of Molecular Medicine and Genetics and Institute of Neuroscience, Medical College of Georgia, Augusta, Georgia 30912, USA.
J Neurosci Res. 2009 Dec;87(16):3535-45. doi: 10.1002/jnr.22170.
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-GlcNAc), 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-GlcNAc is expressed in NSCs or what the function of this expression is. In this study, we evaluated the patterns and possible functions of O-GlcNAcylation in mouse embryonic neuroepithelial cells (NECs), which are known to be rich in NSCs. We confirmed the expression of O-GlcNAc transferase, O-GlcNAcase, and several O-GlcNAcylated proteins in NECs. Treatment of NECs with O-GlcNAcase inhibitors, PUGNAc and streptozotocin, induced robust accumulation of O-GlcNAc in NECs and reduction of number of NECs. In O-GlcNAcase inhibitor-treated NECs, the Ras-mitogen-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-GlcNAc is involved in cell death signaling in NECs. Furthermore, in NECs, we identified an O-GlcNAc-modified protein, Sp1 transcription factor. Our study is the first to evaluate expression and functions of O-GlcNAc in NECs.
在神经干细胞（NSCs）中，糖缀合物和碳水化合物抗原不仅已知作为细胞分化和发育的优异细胞表面生物标志物，而且在决定细胞命运方面发挥重要的功能作用。O-连接的β-N-乙酰氨基葡萄糖（O-GlcNAc），其修饰丝氨酸和苏氨酸残基上的核蛋白和细胞质蛋白，也有望发挥重要的调节作用。然而，尚不清楚 O-GlcNAc 是否在 NSCs 中表达，或者这种表达的功能是什么。在这项研究中，我们评估了 O-GlcNAc 糖基化在已知富含 NSCs 的小鼠胚胎神经上皮细胞（NECs）中的模式和可能的功能。我们证实了 O-GlcNAc 转移酶、O-GlcNAcase 和几种 O-GlcNAc 化蛋白在 NECs 中的表达。用 O-GlcNAcase 抑制剂 PUGNAc 和链脲佐菌素处理 NECs，可诱导 NECs 中 O-GlcNAc 的大量积累，并减少 NECs 的数量。在 O-GlcNAcase 抑制剂处理的 NECs 中，Ras-有丝分裂原激活的蛋白激酶途径和磷脂酰肌醇 3-激酶-Akt 途径，分别对增殖和存活很重要，分别是完整的，但细胞死亡的执行者 caspase-3 被激活。这些结果表明 O-GlcNAc 可能参与 NECs 中的细胞死亡信号转导。此外，在 NECs 中，我们鉴定了一种 O-GlcNAc 修饰的蛋白质 Sp1 转录因子。我们的研究首次评估了 O-GlcNAc 在 NECs 中的表达和功能。
