THE INTERPHOTORECEPTOR MATRIX: COMPONENTS AND FUNCTIONS

光感受器间基质(Ipm)是细胞外的薄层。 在正常脊椎动物的眼睛中占据视网膜下空间的物质。因为 它位于神经视网膜和色素上皮(RPE)之间， IPM处于战略地位，可以履行几项重要职能 对于视网膜来说。IPM可能参与视网膜营养，retinold 运输、酶消化或吞噬脱落的盘状物质，和/或 视网膜粘连。拟议研究的长期目标是 确定和研究该基质的生化成分可能是 来维持视网膜的健康，并检查它们是如何 功能。 我们目前的研究主要集中在IPM蛋白上。这项建议的范围是 仅限于四个具体目标：(1)将结构与功能相关联 光感受器间视黄醇结合蛋白(IRBP)，并检测其 作用于靶组织的机制。仅在IPM中发现，IRBP可能 在视觉周期的类维A酸类物质的运输中起作用。方法 包括高效液相色谱法和荧光法(用于分析IRBP配体及其 与其他蛋白质的交换)；物理化学技术(用于检查 IRBP不同寻常的大小和形状，并作为可能功能的探针 结构域)；放射性标记IRBP与RPE的生化结合研究 视网膜)膜；以及这些组织的放射自显影以寻找 IRBP和维生素A的内吞作用(2)原位分析IPM (RPE溶酶体来源)水解酶的组织化学，它可能 在吞噬之前，开始消化脱落的盘状物。 (3)确定来自邻近组织的哪些细胞类型负责 IPM蛋白的生物合成；这项研究涉及培养纯细胞 并分析它们的分泌产物。我们将进行调查 还有IPM蛋白的命运，以及某些视网膜疾病的影响 (如啮齿动物退化)对IPM-蛋白质组成和 新陈代谢。(4)筛选IPM，寻找增强IPM功能的因素 RPE和视网膜。这一目标包括审查IPM对(A)的影响 开始吞噬(通过测量RPE细胞吞噬ROS)； (B)视网膜粘连(通过研究离子和水在 RPE)和(C)视网膜营养(通过分析 IPM中的营养物质和废物)。 预计对IPM的拟议调查将增加 我们对视网膜如何保持健康的知识，并提供 关于疾病状态下功能故障的线索。

The interphotoreceptor matrix (IPM) is the thin layer of extracellular material occupying the subretinal space in normal vertebrate eyes. Because it is located between the neural retina and the pigment epithelium (RPE), the IPM is in a strategic position to perform several important functions for the retina. The IPM could be involved in retinal nutrition, retinold transport, enzymatic digestion or phagocytosis shed disc material, and/or retinal adhesion. The long-term objective of the proposed research is to identify and investigate biochemical components of this matrix that may be required to maintain the health of the retina, and to examine how they function. Our studies currently focus on IPM proteins. The scope of this proposal is limited to four specific aims: (1) Correlate structure with function for interphotoreceptor retinol-binding protein (IRBP), and examine its mechanism of action at target tissues. Found only in the IPM, IRBP may have a role in transport of retinoids for the visual cycle. Methods include HPLC and fluorescence (for analysis of IRBP's ligands and their exchange with other proteins); physicochemical techniques (for examining IRBP's unusual size and shape, and as a probe for possible functional domains); biochemical binding studies of radiolabelled IRBP to RPE (and retina) membranes; and autoradiography of these tissues to search for endocytosis of IRBP and vitamin A. (2) Analyze the IPM, by in situ histochemistry, for hydrolytic enzymes (of RPE lysosomal orgin), which may begin the process of digesting shed disc packets prior to phagocytosis. (3) Identify which cell types from adjacent tissues are responsible for biosynthesis of IPM proteins; this study involves culturing pure cell populations and analyzing their secreted products. We shall investigate also the fate of IPM proteins, and the impact of certain retinal diseases (such as rodent degenerations) upon IPM-protein composition and metabolism. (4) Screen the IPM for factors enhancing the functioning of RPE and retina. This aim includes examining IPM influence upon (a) initiation of phagocytosis (by measuring engulfment of ROS by RPE cells); (b) retinal adhesion (by investigating flow of ions and water through the RPE); and (c) retinal nutrition (by analyzing concentration-gradients of nutrients and waste products in the IPM). It is anticipated that the proposed investigation of the IPM will increase our knowledge of how the health of the retina is maintained, and provide clues about faulty functioning in disease states.