STRUCTURE AND FUNCTION OF HUMAN SALIVARY MUCINS

唾液分泌物含有两种不同的粘蛋白，一种是高分子量的粘蛋白MG1，另一种是低分子量的粘蛋白MG2。粘蛋白保护口腔表面免受干燥，在下表层和外部环境之间形成选择性渗透扩散屏障，润滑硬组织和软组织以减少机械损伤，促进言语和吞咽，并提供物理屏障以防止潜在有害微生物和病毒的定植。我们已经证明MG1实际上是粘蛋白基因产物的混合物，包含MUC4， MUC5B和一种新的唾液粘蛋白（NSM），而MG2是MUC7基因编码的单基因产物。MG1和MG2在大唾液腺和小唾液腺中有差异表达，本项目的总体目标是了解它们的结构特征和功能特性。该项目的具体目标是：1。通过鉴定一种新的唾液黏液蛋白（NSM）和阐明MUC4的c端序列，确定包含MG1的黏液蛋白基因产物的结构组织和序列。2. 利用在COS-7细胞中表达的粘蛋白构建体研究MUC4、MUC5B和NSM的生物合成和组装。3. 评估MG2与口腔微生物的相互作用，并研究MG2与酵母双杂交系统中其他唾液蛋白的异型复合物。4. 应用免疫组织化学和原位杂交技术研究三叶肽在大、小唾液腺中的表达。5. 检测唾液分泌物和全唾液中的MG1和MG2水平，并使用黏液特异性捕获elisa测定分泌谱。

Salivary secretions contain two distinct mucins, a high molecular weight mucin named MG1 and a low molecular weight mucin named MG2. Mucins protect oral surfaces against desiccation, form a selectively permeable diffusion barrier between underlying surfaces and the external environment, lubricate hard and soft tissues to minimize mechanical injury, facilitate speech and swallowing and provide a physical barrier to protect against colonization of potentially harmful microbes and viruses. We have shown that MG1 is actually a mixture of mucin gene products, containing MUC4, MUC5B and a novel salivary mucin (NSM), whereas MG2 is a single gene product encoded in the MUC7 gene. MG1 and MG2 are differentially expressed in major and minor salivary glands and the overall goal of this project is to understand their structural features and functional properties. The specific aims of this project are to: 1. determine the structural organization and sequence of mucin gene products comprising MG1 by characterization of a novel salivary mucin (NSM) and elucidating the C-terminal sequence of MUC4. 2. investigate the biosynthesis and assembly of MUC4, MUC5B and NSM using mucin constructs expressed in COS-7 cells. 3. evaluate interactions of MG2 with oral microbes and investigate MG2 heterotypic complexes with other salivary proteins in the yeast two hybrid system. 4. study expression of trefoil peptides in major and minor salivary glands using immunohistochemistry and in situ hybridization. 5. examine MG1 and MG2 levels in salivary secretions and whole saliva and determine secretion profiles using mucin-specific capture ELISAs.