Joint Research on Acidic Glycoconjugates on Cell Surfaces

本研究的目的是阐明细胞表面糖缀合物的酸性聚糖链在细胞识别和粘附中的作用。得到了以下结果：1。澄清细胞表面糖蛋白中低聚/多唾液酸单元的生物合成机制：(1)通过将含有多唾液酸残基的O-linked glycan链（O-linked polySia）上的鳟鱼多唾液糖蛋白（PSGP） cDNA转染各种哺乳动物细胞的实验，发现O-linked polySia的生物合成机制与存在于糖蛋白（如神经细胞粘附分子）上的N-linked glycan链不同；(2)获得了多个涉及鳟鱼PSGP上O-linked polySia形成的多唾液基转移酶cDNA克隆，目前正在进行结构分析；(3)利用多种针对n -乙酰神经氨酸（Neu5Ac）寡聚物结构的单克隆抗体，研究人员发现含有Neu5Ac的糖蛋白存在于哺乳动物血清和大脑中。其中一些糖蛋白被鉴定为已知的糖蛋白；(4)利用新开发的化学和免疫化学方法，首次在哺乳动物糖蛋白中发现了N-glylcolyneuramic acid （Neu5Gc）的新型寡聚物结构。酸性聚糖链在受精配子相互作用中的作用：(1)建立了一种评估脱胺神经氨酸（KDN）残基依赖的精卵结合的检测方法，用于检测鳟鱼精子的卵受体糖蛋白，目前正在研究KDN残基直接参与精子与卵子的结合；(2)在禽类中发现了小鼠透明带糖蛋白C （ZPC）的同源物，并对其进行了cDNA克隆。多sia或含kdn的糖链在细胞生长活性中的调节作用的阐明：kdn糖链在人肺细胞中被证明是一种发育阶段特异性的活化剂以及肿瘤抗原。目前正在开发检测kdn糖苷的单克隆抗体。少

The objective of this research project was to elucidation of functions of acidic glycan chains of cell surface glycoconjugates in cell recognition and adhesion of animal cells. The following results were obtained :1.Clarification of biosynthetic mechanism of oligo/polysialic acid units in glycoproteins on the cell surface : (1) Based on transfection experiments of cDNA for trout polysialoglycoprotein (PSGP) that contains polysialyl residues on the O-linked glycan chains (O-linked polySia) into various mammalian cells, biosynthetic mechanism of O-linked polySia was shown to be different from that of N-linked glycan chains that are present on glycoproteins such as neural cell adhession molecule ; (2) Several cDNA clones for polysialyltransferases that are involved in formation of O-linked polySia on trout PSGP were obtained, and their structural analysis are now underway ; (3) Use of various monoclonal antibodies specific to oligomeric structures of N-acetylneuraminic acid (Neu5Ac) enabl … More ed to reveal that oligoNeu5Ac-containing glycoproteins were found in mammalian sera and brains. Some of these glycoproteins were identified as known glycoproteins ; (4) Novel oligomeric structure of N-glylcolyneuramic acid (Neu5Gc) was first found in mammalian glycoproteins using newly developed chemical and immunochemical methods.2.Role of acidic glycan chains in gamete interactions at fertilization : (1) An assay method of assessing the deaminoneuraminic acid (KDN) residue-dependent sperm-egg binding was developed for detecting the egg receptor glycoproteins for sperm in trout, and direct involvement of KDN residues in sperm binding to eggs are now being examined ; (2) An avian homologue of mouse zona pellucida glycoprotein C (ZPC) was found and its cDNA cloning was done.3.Elucidation of regulatory roles of polySia- or KDN-containing glycan chains in growth activity of tum or cells : KDN-glycan chains were shown to be a developmental stage specific actigen as well as a tumor antigen in human lung cells. Development of monoclonal antibodies to detect the KDN-glycosides is now underway. Less