STRUCTURE AND FUNCTION OF HUMAN SALIVARY MUCINS

唾液分泌物含有两种不同的粘蛋白，称为MG 1的高分子量粘蛋白和称为MG 2的低分子量粘蛋白。 粘蛋白保护口腔表面免受干燥，在下面的表面和外部环境之间形成选择性可渗透的扩散屏障，润滑硬组织和软组织以使机械损伤最小化，促进言语和吞咽，并提供物理屏障以防止潜在有害的微生物和病毒的定植。 我们已经表明，MG 1实际上是一个粘蛋白基因产物的混合物，含有MUC 4，MUC 5 B和一种新的唾液粘蛋白（NSM），而MG 2是一个单一的基因产物编码的MUC 7基因。 MG 1和MG 2在大唾液腺和小唾液腺中差异表达，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.通过表征一种新的唾液粘蛋白（NSM）并阐明MUC 4的C-末端序列，确定包含MG 1的粘蛋白基因产物的结构组织和序列。 2.使用在COS-7细胞中表达的粘蛋白构建体研究MUC 4、MUC 5 B和NSM的生物合成和组装。 3.评价MG 2与口腔微生物的相互作用，并在酵母双杂交系统中研究MG 2与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、小涎腺中的表达。 5.检查唾液分泌物和全唾液中的MG 1和MG 2水平，并使用粘蛋白特异性捕获ELISA确定分泌概况。

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.