STRUCTURE AND BIOSYNTHESIS OF SELECTIN LIGANDS

项目I-选择素配体的结构和生物合成（Minoru Fukuda，Ph.D.）在上一个供资期间，我们在这一领域取得了重大进展。首先，我们发现高内皮微静脉（HEV）中的6-磺基唾液酸刘易斯x可以在核心2分支和延伸的核心1 O-聚糖中形成。新型磺基转移酶（LSST）和核心1延伸酶（核心1-β 3GlcNAcT）的表达表明，这些结构在双触角O-聚糖中的表达导致高活性L-选择素配体。第二，肿瘤细胞上sialyl刘易斯x的过度表达导致那些肿瘤细胞被自然杀伤（NK）细胞溶解，而sialyl刘易斯x的适度表达促进肿瘤转移。基于这些发现，提出了两个主要的研究领域：I。在外周淋巴结和派伊尔集合淋巴结的HEV中L-选择素配体的结构和功能的阐明。我们将与John Lowe博士、Fukuda博士和Ole Hindsgaul博士合作，确定外周和粘膜淋巴结中HEV的L-选择素配体的完整结构，并通过产生突变小鼠确定6-磺基唾液酸刘易斯x是L-选择素配体的作用。二.糖类在肿瘤转移中的作用。我们将与Fukuda博士和John Lowe博士合作，确定唾液酸刘易斯x的量是否在促进肿瘤转移或NK细胞介导的细胞溶解中起主要作用。我们还将确定从肿瘤细胞分离的细胞表面碳水化合物是否抑制肿瘤转移或NK细胞介导的细胞溶解。这些研究将使我们了解选择素配体的结构和生物合成以及肿瘤细胞表面碳水化合物在肿瘤转移和免疫细胞识别中的作用。

Project I- Structure and Biosynthesis of Selectin Ligands (Minoru Fukuda, Ph.D.) In the previous funding period, we have made critical progress in this field. First, we discovered that 6-sulfo sialyl Lewis x in high endothelial venules (HEV) can be formed in core2 branch and extended core1 O- glycans. Expression of novel sulfotransferase (LSST) and core1 extension enzyme (core1-beta3GlcNAcT) demonstrated that the expression of these structures in biantennary O-glycans leads to highly active L-selectin ligands. Second, that excessive expression of sialyl Lewis x on tumor cells results in cytolysis of those tumor cells by nature killer (NK) cells, while moderate expression of sialyl Lewis x facilitates tumor metastasis. Based on these findings, two major areas of study are proposed: I. Elucidation of structure and function of L-selectin ligands in HEV at peripheral lymph nodes and Peyer's patches. In collaboration with Drs. John Lowe, Michiko Fukuda, and Ole Hindsgaul, we will determine the complete structure of L-selectin ligands at HEV in peripheral and mucosal lymph nodes, and determine the roles of 6-sulfo sialyl Lewis x is an L-selectin ligand by generating a mutant mouse. II. Roles of carbohydrates in tumor metastasis. In collaboration with Drs. Michiko Fukuda and John Lowe, we will determine if the amount of sialyl Lewis x plays a major role in facilitating tumor metastasis or NK cell-mediated cytolysis. We will also determine if cell surface carbohydrates isolated from tumor cells inhibit tumor metastasis or NK cell-mediated cytolysis. These studies will allow us to understand the structure and biosynthesis of selectin ligands and the roles of cell surface carbohydrates of tumor cells in tumor metastasis and immune cell recognition.