Marchal I, Jarvis D L, Cacan R, Verbert A
Laboratoire de Glycobiologie Structurale et Fonctionnelle, CNRS UMR no8576, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France.
Biol Chem. 2001 Feb;382(2):151-9. doi: 10.1515/BC.2001.023.
Our growing comprehension of the biological roles of glycan moieties has created a clear need for expression systems that can produce mammalian-type glycoproteins. In turn, this has intensified interest in understanding the protein glycosylation pathways of the heterologous hosts that are commonly used for recombinant glycoprotein expression. Among these, insect cells are the most widely used and, particularly in their role as hosts for baculovirus expression vectors, provide a powerful tool for biotechnology. Various studies of the glycosylation patterns of endogenous and recombinant glycoproteins produced by insect cells have revealed a large variety of O- and N-linked glycan structures and have established that the major processed O- and N-glycan species found on these glycoproteins are (Gal beta1,3)GalNAc-O-Ser/Thr and Man3(Fuc)GlcNAc2-N-Asn, respectively. However, the ability or inability of insect cells to synthesize and compartmentalize sialic acids and to produce sialylated glycans remains controversial. This is an important issue because terminal sialic acid residues play diverse biological roles in many glycoconjugates. While most work indicates that insect cell-derived glycoproteins are not sialylated, some well-controlled studies suggest that sialylation can occur. In evaluating this work, it is important to recognize that oligosaccharide structural determination is tedious work, due to the infinite diversity of this class of compounds. Furthermore, there is no universal method of glycan analysis; rather, various strategies and techniques can be used, which provide glycobiologists with relatively more or less precise and reliable results. Therefore, it is important to consider the methodology used to assess glycan structures when evaluating these studies. The purpose of this review is to survey the studies that have contributed to our current view of glycoprotein sialylation in insect cell systems, according to the methods used. Possible reasons for the disagreement on this topic in the literature, which include the diverse origins of biological material and experimental artifacts, will be discussed. In the final analysis, it appears that if insect cells have the genetic potential to perform sialylation of glycoproteins, this is a highly specialized function that probably occurs rarely. Thus, the production of sialylated recombinant glycoproteins in the baculovirus-insect cell system will require metabolic engineering efforts to extend the native protein glycosylation pathways of insect cells.
我们对聚糖部分生物学作用的理解不断加深，这明确需要能够产生哺乳动物型糖蛋白的表达系统。相应地，这激发了人们对了解常用于重组糖蛋白表达的异源宿主蛋白质糖基化途径的兴趣。其中，昆虫细胞是使用最广泛的，特别是作为杆状病毒表达载体的宿主时，为生物技术提供了强大工具。对昆虫细胞产生的内源性和重组糖蛋白糖基化模式的各种研究揭示了大量的O-连接和N-连接聚糖结构，并确定在这些糖蛋白上发现的主要加工后的O-和N-聚糖种类分别是（Galβ1,3）GalNAc-O-Ser/Thr和Man3（Fuc）GlcNAc2-N-Asn。然而，昆虫细胞合成和分隔唾液酸以及产生唾液酸化聚糖的能力与否仍存在争议。这是一个重要问题，因为末端唾液酸残基在许多糖缀合物中发挥着多种生物学作用。虽然大多数研究表明昆虫细胞来源的糖蛋白不会被唾液酸化，但一些严格控制的研究表明唾液酸化可能会发生。在评估这项工作时，重要的是要认识到由于这类化合物的无限多样性，寡糖结构测定是一项繁琐的工作。此外，没有通用的聚糖分析方法；相反，可以使用各种策略和技术，它们为糖生物学研究人员提供或多或少精确和可靠的结果。因此，在评估这些研究时，考虑用于评估聚糖结构的方法很重要。本综述的目的是根据所使用的方法，综述那些促成我们目前对昆虫细胞系统中糖蛋白唾液酸化看法的研究。将讨论文献中关于这个主题存在分歧的可能原因，包括生物材料的不同来源和实验假象。归根结底，似乎如果昆虫细胞具有对糖蛋白进行唾液酸化的遗传潜力，这也是一种可能很少发生的高度专业化功能。因此，在杆状病毒-昆虫细胞系统中生产唾液酸化的重组糖蛋白将需要代谢工程努力来扩展昆虫细胞的天然蛋白质糖基化途径。
