O-Fucose Monosaccharide of Drosophila Notch Has a Temperature-sensitive Function and Cooperates with O-Glucose Glycan in Notch Transport and Notch Signaling Activation
O-Fucose Monosaccharide of Drosophila Notch Has a Temperature-sensitive Function and Cooperates with O-Glucose Glycan in Notch Transport and Notch Signaling Activation
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DOI：
10.1074/jbc.m114.616847
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发表时间：
2015-01-02
影响因子：
4.8
通讯作者：
Matsuno, Kenji
中科院分区：
文献类型：
--
作者：
Ishio, Akira;Sasamura, Takeshi;Matsuno, Kenji
背景：O-岩藻糖单糖对 Notch 的需求尚不完全清楚。结果：Notch 上 O-岩藻糖单糖的丢失导致 Notch 信号传导的温度敏感性丢失。结论：Notch的O-岩藻糖单糖具有温度敏感功能，并与O-葡萄糖聚糖协同激活Notch信号。意义：我们的研究结果阐明了蛋白质上不同形式的糖基化如何影响蛋白质功能。Notch (N) 是一种跨膜受体，可介导许多细胞命运决定所必需的细胞间相互作用。 N 具有许多表皮生长因子样重复序列，这些重复序列被蛋白质 O-岩藻糖基转移酶 1 (O-Fut1) 进行 O-岩藻糖基化，而 O-fut1 基因对于 N 信号转导至关重要。然而，单糖 O-岩藻糖对 N 的作用尚不清楚，因为 O-Fut1 似乎也具有 O-岩藻糖基转移酶活性独立的功能，包括作为 N 特异性伴侣。这种与酶活性无关的功能可以解释 O-fut1 在 N 信号传导中的重要作用。为了评估单糖O-岩藻糖修饰在N信号传导中的作用，在这里，我们生成了O-fut1的敲入突变体（O-fut1（R245A knock-in）），它表达缺乏O-岩藻糖基转移酶活性但保持N特异性伴侣活性的突变蛋白。利用O-fut1（R245A敲入）和其他废除N的O-岩藻糖基化的基因突变，我们发现N的单糖O-岩藻糖修饰具有温度敏感功能，这对于N信号传导至关重要。 Rumi 催化的 O-岩藻糖单糖和 O-葡萄糖聚糖修饰在 N 信号传导的激活中发挥冗余作用。我们还表明，这两种修饰的冗余功能是导致细胞表面存在氮的原因。我们的研究结果阐明了蛋白质上不同形式的糖基化如何影响蛋白质的功能。
Background: The requirement of O-fucose monosaccharide on Notch is not fully understood. Results: Loss of O-fucose monosaccharide on Notch caused temperature-sensitive loss of Notch signaling. Conclusion:O-Fucose monosaccharide of Notch has a temperature-sensitive function and cooperates with O-glucose glycan in Notch signal activation. Significance: Our findings elucidate how different forms of glycosylation on a protein influence protein functions.Notch (N) is a transmembrane receptor that mediates the cell-cell interactions necessary for many cell fate decisions. N has many epidermal growth factor-like repeats that are O-fucosylated by the protein O-fucosyltransferase 1 (O-Fut1), and the O-fut1 gene is essential for N signaling. However, the role of the monosaccharide O-fucose on N is unclear, because O-Fut1 also appears to have O-fucosyltransferase activity-independent functions, including as an N-specific chaperon. Such an enzymatic activity-independent function could account for the essential role of O-fut1 in N signaling. To evaluate the role of the monosaccharide O-fucose modification in N signaling, here we generated a knock-in mutant of O-fut1 (O-fut1(R245A knock-in)), which expresses a mutant protein that lacks O-fucosyltransferase activity but maintains the N-specific chaperon activity. Using O-fut1(R245A knock-in) and other gene mutations that abolish the O-fucosylation of N, we found that the monosaccharide O-fucose modification of N has a temperature-sensitive function that is essential for N signaling. The O-fucose monosaccharide and O-glucose glycan modification, catalyzed by Rumi, function redundantly in the activation of N signaling. We also showed that the redundant function of these two modifications is responsible for the presence of N at the cell surface. Our findings elucidate how different forms of glycosylation on a protein can influence the protein's functions.