Roles for Glycosylation in Notch Signaling

描述(申请人提供)：缺口受体是细胞表面 转导信号以控制细胞命运和细胞分裂的糖蛋白 后生动物。结构性或失调性信号导致发育 缺陷和癌症。与Notch结合并刺激信号的配体 转导途径为Delta和锯齿状/锯齿状。我们已经展示了与 其他的果蝇和哺乳动物边缘蛋白有一个 β3N-乙酰氨基葡萄糖基转移酶的活性和直接作用于Notch来增加 GIcNAc到O-岩藻糖在Notch EGF重复序列上的作用，从而调节配体诱导 凹槽信号。在果蝇和哺乳动物细胞中，边缘行为细胞 自主地抑制对锯齿状(锯齿状)的凹槽反应 增强对德尔塔的凹槽反应。我们请来了一位异质文化记者 Notch表达CHO细胞中躁狂或精神错乱的检测 抑制对Jagged1的反应。我们使用了一组CHO糖基化 突变体表明条纹对Notch信号的抑制不需要 复杂或杂化的N-葡聚糖或唾液酸，但不需要 连接到凹槽EGF上的O-岩藻糖上的条纹重复，随后的作用 因此，岩藻糖基转移酶和β4GalT-1是新的调节剂。 Notch信令。利用CHO糖基化突变体，共培养Notch信号 和可溶性配基结合试验，以及小鼠突变体，我们建议1)鉴定 锯齿状和Delta诱导信号转导所需的不同0-岩藻糖聚糖 通过Notch受体1、2、3和4以及通过 哺乳动物边缘(狂躁、狂躁和激进)；2)测定生化 边缘作用扰乱Notch信号的机制；以及3)识别 基因失活对小鼠体内Notch信号的影响 编码新的Notch信令调制器。

DESCRIPTION (provided by applicant): Notch receptors are cell surface glycoproteins that transduce signals to control cell fate and cell division in metazoans. Constitutive or disregulated signaling leads to developmental defects and cancer. The ligands that bind to Notch and stimulate signal transduction are Delta and Serrate/Jagged. We have shown in collaboration with others that Drosophila and mammalian fringe proteins have a beta3N-acetylglucosaminyltransferase activity and act directly on Notch to add GIcNAc to O-fucose on Notch EGF repeats, thereby modulating ligand-induced Notch signaling. In Drosophila and mammalian cells, fringe acts cell autonomously to inhibit the Notch response to Serrate(Jagged) while potentiating the Notch response to Delta. We have used a co-culture reporter assay to show that manic or lunatic fringe in Notch expressing CHO cells inhibit the response to Jagged1. We have used a panel of CHO glycosylation mutants to show that inhibition of Notch signaling by fringe does not require complex or hybrid N-glycans or sialic acid but does require the action of fringe on O-fucose attached to Notch EGF repeats, and the subsequent action of beta4GalT- 1. Thus O. fucosyltransferase and beta4GalT-1 are novel modulators of Notch signaling. Using CHO glycosylation mutants, co-culture Notch signaling and soluble ligand binding assays, and mouse mutants, we propose 1 )To identify the different 0-fucose glycans required for Jagged- and Delta-induced signaling by Notch receptors 1, 2, 3 and 4 and for the modulation of Notch signaling by mammalian fringes (manic, lunatic and radical); 2) To determine the biochemical mechanism by which fringe action perturbs Notch signaling; and 3) To identify in vivo consequences to Notch signaling in the mouse of inactivating the genes encoding new modulators of Notch signaling.