HEPATIC AND COLONIC SIALYLTRANSFERASE EXPRESSION

细胞唾液酸组分的顺序修饰 粘附分子和其他糖蛋白是其中一种机制， 正常的细胞分化过程。 的唾液酸寡糖， 异常的糖蛋白也与糖尿病的病理生理学有关， 各种疾病，包括转移性结肠直肠癌。 的合成 每个唾液酸键由特定的唾液酸转移酶催化， 因此，这些酶活性的波动可能会导致 在分化等基本生物过程中起着关键作用 和转移行为。 为了最终理解 协调不同唾液酸转移酶表达的机制 在正常和病变组织中，本申请的目的是： 在真核细胞中表达人唾液酸转移酶的cDNA， 描绘了由不同编码的蛋白质催化的唾液酸键， 蛋白质;进行人唾液酸转移酶mRNA的组织调查; 比较唾液酸转移酶mRNA表达和酶活性， 人癌细胞系;并在同一组细胞系中进行研究 可能影响药物水平的药物的调节作用 唾液酸转移酶表达。 中国仓鼠卵巢细胞将 用质粒中的唾液酸转移酶cDNA的构建体转染 向量。 表达的唾液酸转移酶的活性将是 通过测定其受体底物和分析 合成的低聚糖。 组织调查将是 通过北方杂交在人类手术标本中进行 分析和S1保护测定。 癌细胞小组将包括 地塞米松、正丁酸盐、视黄酸和甲状腺激素。 结果 将形成理解的决定因素的基础， 唾液酸转移酶的活性及其生物学研究的前景 唾液酸化的功能。

Sequential modification of the sialic acid component of cell adhesion molecules and other glycoproteins is one of the mechanisms by which normal cell differentiation proceeds. The sialyl oligosaccharides of aberrant glycoproteins have also been implicated in the pathophysiology of various diseases, including metastatic colorectal cancer. The synthesis of each sialyl linkage is catalyzed by a specific sialyltransferase and fluctuations in the activities of these enzymes may therefore play a critical role in such fundamental biological processes as differentiation and metastatic behavior. Towards an eventual understanding of the mechanisms that coordinate expression of the different sialyltransferases in normal and diseased tissues, objectives of this application are: to express cDNAs for human sialyltransferases in eucaryotic cells and delineate the sialyl linkages that are catalyzed by the different encoded proteins; to perform a tissue survey of human sialyltransferase mRNAs; to compare sialyltransferase mRNA expression and enzyme activity in a panel of human cancer cell lines; and to investigate in the same panel of cell lines the regulatory effects of agents that are likely to influence levels of sialyltransferase expression. Chinese hamster ovary cells will be transfected with constructs of the sialyltransferase cDNAs in plasmid vectors. The activities of expressed sialyltransferases will be characterized by determination of their acceptor substrates and analysis of the oligosaccharides that are synthesized. The tissues survey will be conducted in human surgical specimens through Northern hybridization analysis and S1 protection assays. The panel of cancer cells will include dexamethasone, n-butyrate, retinoic acid and thyroid hormone. The results will form the basis for an understanding of the determinants of the activities of sialyltransferases and future studies of the biological functions of sialylation.