REGULATION OF HUMAN SALIVARY MUCIN GLYCOSYLATION

人类唾液粘蛋白的明显机械贡献，凭借 在脱辅基蛋白核心周围密集堆积的聚糖， 口腔软组织的润滑早已被认识到。 更 最近的研究表明，唾液粘蛋白的额外能力， 调节口腔的生物环境， 与口腔细菌的相互作用。 MG 2上聚糖结构的结合 人低分子量唾液粘蛋白MUC 7特异性地 与细菌受体有关。 SA α 2，3Ga 1 β 1，3GalNAC-链，沿着两种其他核心1型 链，Fucalpha 1，2Ga 1Beta 1，3GalNAc-及其共同前体。 Ga 1 β 1，3GalNAC-，包含MG 2上大部分聚糖链。 已经记录了MG 2的两种主要同种型，MG 2a和MG 2b;它们是 通过唾液酸化的-和 岩藻糖基化核心1寡糖。 作为了解分子和细胞因子的第一步， 决定人类唾液粘蛋白中的聚糖组成， MG 2上的唾液酸化和岩藻糖基化核心1寡糖将被 详细检查。 第一步将是分子 通过分析cDNA和基因组序列， 同源糖基转移酶、α 2，3-唾液酸转移酶和 α 1，2-岩藻糖基转移酶。 分子探针产生的结果， 这些研究将被用来检查核心的差异合成 1低聚糖。 MG 2亚型产生于 分泌细胞的不同亚群表达不同水平的 唾液酸转移酶和岩藻糖基转移酶将由 原位杂交方法。 此外，在每个细胞中， 表达岩藻糖和唾液酸转移酶，潜在的竞争 这些酶之间的共同底物可能决定了最终的 唾液酸化和岩藻糖基化结构的比例。 这种可能性，如 以及脱粘蛋白一级结构对分化的影响 糖基化，将通过转染和表达来检查 脱粘蛋白和糖基转移酶序列。 最后，将努力 用于鉴定唾液腺来源的细胞系， 调节粘蛋白表达。 这些行最终将在 调节脱粘蛋白的途径的分子解剖， 唾液腺中糖基转移酶的表达。

The obvious mechanical contributions of human salivary mucins, by virtue of glycans densely packed around apoprotein cores, to protection and lubrication of oral cavity soft tissues have long been recognized. More recent studies demonstrated the additional ability of salivary mucins to modulate the biological environment of the oral cavity by direct interaction with oral bacteria. Binding of glycan structures on MG2 (MUC7), the human low molecular weight salivary mucin, to specific bacterial receptors have been implicated. SAalpha2,3Ga1Beta1, 3GalNAC- chains, along with two other Core 1 type chains, Fucalpha1,2Ga1Beta1,3GalNAc- and their common precursor. Ga1Beta1,3GalNAC-, comprise the major proportion of glycan chains on MG2. Two major isoforms of MG2, MG2a and MG2b, have been documented; these are putatively generated by differential expression of the sialylated- and fucosylated-Core 1 oligosaccharides. As a first step in understanding the molecular and cellular factors that dictate glycan composition in human salivary mucins, the biosynthesis of the sialylated- and fucosylated-Core 1 oligosaccharides on MG2 will be examined in detail. The first step will be the molecular characterization, by analysis of cDNA and genomic sequences, of the cognate glycosyltranferases, the alpha2,3-sialyltransferase and the alpha1,2-fucosyltransferase. Molecular probes generated as a result of these studies will be used to examine differential synthesis of the Core 1 oligosaccharides. The possibility that the MG2 isoforms result from different sub-populations of secretory cells expressing different levels of the sialytransferase and fucosyltransferase will be addressed by the in situ hybridization approach. Furthermore, within each cell that expresses both the fucosy- and sialytransferases, potential competition between these enzymes for the common substrate may dictate the final ratio of sialylated and fucosylated structures. This possibility, as well as the influence of apomucin primary structure on the differential glycosylation, will be examined by means of transfection and expression of apomucin and glycosyltransferase sequences. Finally, efforts will be made to identify cell lines of salivary gland origin that retain regulated mucin expression. These lines will be ultimately useful in the molecular dissection of pathways that regulate apomucin and glycosyltransferase expression in salivary glands.