Fine-Tuning the Notch Signaling Pathway via O-Glucosylation

描述(申请人提供)：在进化上保守的途径中的缺口信号，调节动物的不同过程，包括干细胞维持、细胞命运指定、学习和记忆以及血管生成。保持Notch信号的最佳水平对于人类的正常发育和健康是至关重要的，因为导致Notch通路活性增加或减少的突变会导致许多人类疾病，包括癌症和发育性疾病。此外，对Notch通路活性的治疗操作在Notch相关疾病和再生医学中具有重要意义。我们已经确定了一种进化上保守的酶，称为RUMI，它将O-连接的葡萄糖添加到Notch受体的特定EGF重复序列中，并在果蝇和哺乳动物中调节Notch信号。我们的数据表明，果蝇Notch上O-葡萄糖残基的数量和分布在很大程度上决定了Notch信号的强度，哺乳动物的Notch信号对RUMI基因的剂量敏感是特定的背景。我们的初步数据表明，新发现的酶将一个或两个木糖残基加到O-葡萄糖上，可以进一步调节Notch信号。我们的数据有力地表明，O-葡萄糖及其延伸形式在Notch上的水平和分布密切地调节着Notch信号的强度。我们将结合果蝇遗传学、基于细胞的信号分析和生化实验，阐明碳水化合物微调Notch途径的潜在机制。从长远来看，这个项目有可能建立工具，通过控制O-葡萄糖和木糖的水平来改变Notch信号的活性 缺口蛋白。

DESCRIPTION (provided by applicant): Notch signaling in an evolutionarily conserved pathway that regulates diverse processes in animals, including stem cell maintenance, cell fate specification, learning and memory, and angiogenesis. Maintaining an optimal level of Notch signaling is essential for normal human development and human health, as mutations that result in increased or decreased activity of the Notch pathway cause a number of human diseases, including cancer and developmental disease. Moreover, therapeutic manipulation of the Notch pathway activity is of great interest in Notch-related diseases and in regenerative medicine. We have identified an evolutionarily conserved enzyme called Rumi, which adds O-linked glucose to specific EGF repeats of Notch receptors and regulates Notch signaling in both Drosophila and mammals. Our data indicate that the number and distribution of O-glucose residues on the Drosophila Notch determines the strength of Notch signaling over a wide range, and that mammalian Notch signaling is sensitive to Rumi gene dosage is specific contexts. Our preliminary data indicate that addition of one or two xylose residue to O-glucose by newly identified enzymes can further regulate Notch signaling. Our data strongly suggest that the level and distribution of O-glucose and its extended forms on Notch tightly regulate the strength of Notch signaling. We will elucidate the mechanisms underlying the fine-tuning of the Notch pathway by carbohydrates by using a combination of Drosophila genetics, cell-based signaling assays and biochemical experiments. In the long run, this project has the potential to establish tools to alter the activity of Notch signaling by manipulating the level of O-glucose and xylose on Notch proteins.