TEAR GLAND FLUID FORMATION

本项目将重点研究质膜的细胞内运输 从兔泪腺分离的腺泡细胞中的成分。 的 泪腺是伺服机构中的效应器官， 保持眼表健康，并减少泪液分泌 功能导致疼痛的干眼病。 泪液分泌不足可以 由激素紊乱或局部自身免疫现象引起。 特别紧迫的是，导致自身免疫性疾病的机制 泪腺功能不全的症状。 这种现象往往 伴有自身免疫性唾液腺功能障碍， 口腔健康的后果，以及许多系统性疾病 至少部分由免疫复合物沉积引发。 这些 干燥综合征的特征症状，影响一个以上的 55岁以上的美国女性。 最近的亚细胞分级和形态学研究表明， Na，K-ATPase和其他腺泡细胞质膜蛋白参与 在往返于细胞内池的大量再循环运输中， 其似乎被组织成早期和晚期内吞隔室。 分离机制似乎允许流体相之间的交通 两个隔室，但允许Na，K-ATPase从晚期到晚期旅行。 早期隔室仅响应于胆碱能刺激。 过度 刺激似乎改变了后期的微区组织 并削弱其参与细胞内 流体相交通。 如此广泛的，分泌物的存在- 受控的细胞内运输提出了一个工作假设， 腺泡细胞通过发挥功能触发局部自身免疫反应 类似于专门的抗原递呈细胞。 初步数据 证实腺泡细胞含有潜在的免疫原性蛋白（LG-1）， Ag 2），它们可以表达机器的几个组件， 抗原呈递，包括组织蛋白酶B， 免疫原性肽片段和II类组织相容性分子， 其可以结合免疫原性片段并将其展示给T细胞。 它 也有可能存在于泪腺中的另外的肽 它可以为T细胞活化提供辅助信号。 的 拟议研究的具体目标是：1）描绘和调查 早期和晚期内吞的微区组织 隔间 2)确定负责重新组织 最佳和过量胆碱能后的晚期内吞隔室 刺激. 3)绘制组织蛋白酶B和 D、LG-Ag 2和II类组织相容性分子，以确定是否 它们可以聚集在与血浆相通的隔室中 膜的 如果该项目探索的假设被证明是正确的， 那么我们在理解 膜转运蛋白的潜在插入和回收，以及 将为试图理解腺泡T细胞活化奠定基础 细胞

This project will focus on the intracellular traffic of plasma membrane constituents in acinar cells isolated from rabbit lacrimal glands. The lacrimal glands are effector organs in a servomechanism that helps maintain the health of the ocular surface, and insufficient lacrimal function leads to painful dry eye conditions. Lacrimal insufficiency can result from hormonal perturbations or from local autoimmune phenomena. It is particularly urgent that the mechanisms leading to autoimmune lacrimal insufficiency be understood. This phenomenon is often accompanied by autoimmune salivary gland dysfunction, with serious consequences for oral health, and by numerous systemic disorders triggered, at least in part, by immune complex deposition. these symptoms characterize Sjogren's Syndrome, which affects more than one million American women over age 55. Recent subcellular fractionation and morphological studies indicate that Na,K-ATPase and other acinar cell plasma membrane proteins participate in an extensive recycling traffic to and from an intracellular pool, which appears to be organized into early and late endocytic compartments. Segregation mechanism appear to permit fluid phase traffic between the two compartments but allow Na,K-ATPase to travel from the late to the early compartment only in response to cholinergic stimulation. Excessive stimulation appears to alter the microdomain organization of the late compartment and to impair its ability to participate in intracellular fluid phase traffic. The existence of such an extensive, secretagogue- controlled intracellular traffic suggests a working hypothesis in which acinar cells trigger local autoimmune reactions by functioning analogously to specialized antigen-presenting cells. Preliminary data confirm that acinar cells contain a potentially immunogenic protein (LG- Ag2) and that they can express several components of the machinery for antigen presentation, including cathepsin B, which might excise immunogenic peptide fragments, and Class II histocompatibility molecules, which might bind immunogenic fragments and display them to T cells. It is also possible that additional peptides occurring in the lacrimal interstitium can provide accessory signals for T cell activation. The specific aims of the proposed studies are to: 1) Delineate and survey the microdomain organizations of the early and late endocytic compartments. 2) Identify mechanisms responsible for re-organizing the late endocytic compartment following optimal and excessive cholinergic stimulation. 3) Map the subcellular distributions of cathepsins B and D, LG-Ag2, and Class II histocompatibility molecules to determine whether they can accumulate in compartments that communicate with the plasma membrane. If the hypotheses explored by the project are proven correct, then progress will have been made in the understanding of events underlying insertion and retrieval of membrane transporters, and the stage will be set for attempts to understand T cell activation by acinar cells.