Joint Research on Acidic Glycoconjugates on Cell Surfaces

本研究旨在阐明细胞表面糖复合物的酸性聚糖链在细胞识别和动物细胞粘附中的功能。1.阐明了细胞表面糖蛋白中寡/聚唾液酸单元的生物合成机制：（1）基于鳟鱼多聚唾液酸糖蛋白（PSGP）cDNA的转染实验，（O-连接的polySia）进入各种哺乳动物细胞，O-连接的polySia的生物合成机制与N-连接的polySia的生物合成机制不同。（2）获得了与鳟鱼PSGP上O-连接的多聚Sia形成有关的多聚唾液酸转移酶的几个cDNA克隆，目前正在进行结构分析;（3）使用对N-乙酰神经氨酸（Neu 5Ac）的寡聚体结构特异的各种单克隆抗体， ...更多信息 艾德揭示了在哺乳动物血清和脑中发现了含寡Neu 5Ac的糖蛋白。其中一些糖蛋白已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-甘氨酰神经氨酸（Neu 5Gc）的新寡聚体结构。2.酸性聚糖链在受精时配子相互作用中的作用：（1）建立了精卵结合的脱氨基神经氨酸（deaminoneuraminicacid，KDN）残基依赖性检测方法，用于检测鳟鱼精子卵受体糖蛋白，（2）发现了一种与小鼠透明带糖蛋白C（ZPC）同源的禽类糖蛋白，并克隆了其cDNA;（3）阐明了含polySia或含KDN的聚糖链在肿瘤或细胞生长活性中的调节作用：在人肺细胞中，已证明KDN-聚糖链是一种发育阶段特异性的激活素以及一种肿瘤抗原。目前正在开发单克隆抗体来检测KDN-糖苷。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