FUNCTIONAL ORGANIZATION OF MEMBRANE DOMAINS IN THE LENS

透镜纤维细胞是人体内最长的上皮细胞。尽管它们的长度，纤维细胞保持在离散的基底，侧和顶端膜域的膜蛋白的极化分布。 这些结构域的独特组成在发育早期建立并积极维持，甚至在伴随纤维细胞分化的快速细胞伸长期间。该建议利用一个综合的方法来研究膜动力学在生活透镜。 初步研究将集中在控制膜合成的各个区域的透镜和机制的膜囊泡的细胞内运输。一个简单的，一个步骤，技术纯化基膜域的成分已经开发出来。 使用该方法，将鉴定基底膜结构域的组分。 在基底膜域的膜和细胞骨架元素的安排表明在住宿和/或迁移的一个新的作用。 实验将测试基底膜结构域在这些功能中的作用。透镜中侧膜的一个显著特征是存在异常丰富的缝隙连接。实验提出了检查透镜间隙连接斑块的形成和稳定性。 此外，在中央纤维细胞中发现了一种新的扩散途径，并将对该途径进行表征。 当纤维细胞到达缝线时，侧膜底物的酪氨酸磷酸化发生。 磷酸化的蛋白质将被识别，并触发膜磷酸化的发育线索将被确定。这些研究将为透镜中的膜动力学提供重要数据。 这些研究特别及时，因为透镜膜缺陷（遗传和生物化学）最近已被证明是人类许多类型白内障的基础。

Lens fiber cells are the longest epithelial cells in the body. Despite their length, fiber cells maintain a polarized distribution of membrane proteins in discrete basal, lateral and apical membrane domains. The unique composition of these domains is established early in development and actively maintained, even during the rapid cellular elongation that accompanies fiber cell differentiation. This proposal utilizes an integrated approach to study membrane dynamics in the living lens. Initial studies will focus on the control of membrane synthesis in various regions of the lens and mechanisms underlying intracellular transport of membrane vesicles. A simple, one-step, technique for purifying components of the basal membrane domain has been developed. Using this method, components of the basal membrane domain will be identified. The arrangement of membrane and cytoskeletal elements at the basal membrane domain suggests a novel role in accommodation and/or migration. Experiments will test the role of the basal membrane domain in these functions. A striking feature of the lateral membranes in the lens is the presence of an extraordinary abundance of gap junctions. Experiments are proposed that examine the formation and stability of lens gap junction plaques. In addition a novel diffusion pathway has been identified in central fiber cells and this pathway will be characterized. Tyrosine phosphorylation of lateral membrane substrates occurs when fiber cells reach the sutures. The phosphorylated proteins will be identified and the developmental cues that trigger membrane phosphorylation will be determined. These studies will provide important data on membrane dynamics in the lens. These studies are particularly timely because lens membrane defects (both genetic and biochemical) have recently been shown to underlie many types of cataract in humans.