Dynamic developmental elaboration of N-linked glycan complexity in the Drosophila melanogaster embryo
Dynamic developmental elaboration of N-linked glycan complexity in the Drosophila melanogaster embryo
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DOI：
10.1074/jbc.m606711200
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发表时间：
2007-03-23
影响因子：
4.8
通讯作者：
Tiemeyer, Michael
中科院分区：
文献类型：
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作者：
Aoki, Kazuhiro;Perlman, Mindy;Tiemeyer, Michael
糖蛋白N-连接寡糖的结构多样性由糖基转移酶活性的表达和调节以及适当受体/供体底物的可用性决定。不同组织和不同发育阶段的细胞利用这些控制点来响应其周围环境而表现出独特的聚糖表达模式。Toll样受体（称为托洛/ Toll-8）的活性在果蝇胚胎中诱导了一种不完全确定但具有神经特异性的聚糖表达模式。要了解由改变的托洛/Toll-8信号传导引起的聚糖表达变化的全部程度，需要表征野生型和突变型胚胎的完整N-连接聚糖谱。通过分析型和制备型高压液相色谱法、多维质谱法和外切糖苷酶消化，对从野生型或突变体胚胎中收获的N-连接聚糖进行直接结构分析，结果显示高甘露糖和少甘露糖聚糖占优势。杂合、复合双触角和三触角聚糖的二、单和非岩藻糖基化形式占总野生型聚糖谱的12%。检测到两个带有N-乙酰神经氨酸的唾液酸化聚糖，这是果蝇中这种修饰的第一个直接证明。正常发育期间聚糖谱的变化与α-甘露糖苷酶II和核心岩藻糖基转移酶活性的增加以及融合叶加工氨基己糖苷酶活性的降低一致。在托洛/toll-8突变体中，预期的二岩藻糖基化聚糖的急剧损失伴随着单岩藻糖基化和非岩藻糖基化杂合聚糖的意外减少以及一些非岩藻糖基化少甘露糖和双触角聚糖的增加。因此，托洛/toll-8信号传导通过影响N-连接聚糖成熟的几个加工步骤影响通量。
The structural diversity of glycoprotein N-linked oligosaccharides is determined by the expression and regulation of glycosyltransferase activities and by the availability of the appropriate acceptor/donor substrates. Cells in different tissues and in different developmental stages utilize these control points to manifest unique glycan expression patterns in response to their surroundings. The activity of a Toll-like receptor, called Tollo/ Toll-8, induces a pattern of incompletely defined, but neural specific, glycan expression in the Drosophila embryo. Understanding the full extent of the changes in glycan expression that result from altered Tollo/Toll-8 signaling requires characterization of the complete N-linked glycan profile of both wild-type and mutant embryos. N-Linked glycans harvested from wildtype or mutant embryos were subjected to direct structural analysis by analytic and preparative high pressure liquid chromatography, by multidimensional mass spectrometry, and by exoglycosidase digestion, revealing a predominance of high mannose and paucimannose glycans. Di-, mono-, and nonfucosylated forms of hybrid, complex biantennary, and triantennary glycans account for 12% of the total wild-type glycan profile. Two sialylated glycans bearing N-acetylneuraminic acid were detected, the first direct demonstration of this modification in Drosophila. Glycan profiles change during normal development consistent with increasing a-mannosidase II and core fucosyltransferase enzyme activities, and with decreasing activity of the Fused lobes processing hexosaminidase. In tollo/toll-8 mutants, a dramatic, expected loss of difucosylated glycans is accompanied by unexpected decreases in monofucosylated and nonfucosylated hybrid glycans and increases in some nonfucosylated paucimannose and biantennary glycans. Therefore, tollo/toll-8 signaling influences flux through several processing steps that affect the maturation of N-linked glycans.