Human nuclear age-related cataract is the most common type of cataract requiring corrective surgery in North America and remains a leading cause of blindness throughout the world. In this competing continuation application the main goal is to identify and characterize the precise cellular changes that produce scattering centers within human nuclei. Significant progress has been made in recent years in characterizing the alterations to fiber cells that may produce increased light scattering within human lens nuclei, as well as to an understanding the nature of aging, compaction and intercellular communication in the normal human lenses. The proposed research will build on the previous successes using morphological approaches and will employ a variety of modern electron microscopy techniques including scanning and transmission electron microscopy, cryo microscopy, 3D tomography, Fourier analysis, fluorescent and brightfield light microscopy and laser scanning and two-photon confocal microscopy. We propose to document the molecular organization of the cytoplasm and the distribution of specialized junctions in normal lenses. Emphasis will be given to junctions containing MEP/Aquaporin0 which have been hypothesized to provide a pathway for water transport and serve as adhering junctions. Membranes isolated from different regions of human lenses will be examined to determine the molecular organization using fluorescent and gold particle labeling and to characterize the adhesive junctions. Changes in the junctions and within the cytoplasm of fiber cells during nuclear cataract formation will be documented, especially the multilamellar bodies we described recently as potential scattering centers. We expect that this work will contribute to a better understanding of the current hypotheses of cataract formation and to strategies that could slow or prevent the progression of cataracts in the elderly.
