Fiber Cell Junctions in Normal and Cataractous Lenses

描述（由申请人提供）：这是一项长期资助的修订竞争性更新，旨在了解人类年龄相关性核性白内障形成的细胞基础，这是人类白内障的最常见形式，也是全球失明的主要原因。在最后一个授权期，在表征纤维细胞膜损伤、纤维细胞胞质中晶体蛋白的分布以及包含被多个脂质双层覆盖的细胞质核心的独特球形颗粒（称为多层体）方面取得了重大进展。值得注意的贡献，该领域提供了理论分析的预测散射从每种类型的细胞损伤。这些研究对核性白内障是由蛋白质聚集成高分子量聚集体引起的普遍观点进行了重要修改。我们的研究结果表明，早期核性白内障的纤维细胞超微结构与老年透明晶状体几乎相同，这表明最初的蛋白质修饰和关联是自然衰老过程的一部分。只有在印度晚期白内障中进行广泛的蛋白质修饰后，才有可能使用电子断层扫描识别潜在的HMW聚集体。我们的研究结果表明，多层体作出了重大贡献，前向散射干扰正常的图像形成在中央凹，这对视力障碍的贡献增加，主要是由氧化应激引起的细胞损伤的年龄和积累。我们建议扩大我们的超微结构研究，采用扫描和透射电子显微镜，电子断层扫描，冷冻电子显微镜和共聚焦/多光子光学显微镜，以表征细胞损伤的各种核性白内障，可以比较年龄相关的核性白内障。改进的保存和分辨率将产生有价值的新信息的年龄相关的转换晶体蛋白及其协会与膜。定量结构数据将进行理论分析，以评估其预测的贡献透镜散射。最近的证据首次表明，自噬和线粒体自噬发生在透镜中，并且自噬最有可能是多层体的来源。我们建议探索在不同年龄的人类和鸡胚晶状体中的多层体形成作为动物模型，这将允许识别和调节参与自噬的基因。营养应激可增强自噬，这在早期透镜发育过程中可能是重要的。这些超微结构的研究和理论分析，预计将导致更好地了解细胞损伤的机制，产生过度的光散射在核性白内障的形成。

DESCRIPTION (provided by applicant): This is a revised competitive renewal of a long-standing grant to understand the cellular basis for the formation of human age-related nuclear cataracts, the most common form of human cataract and a leading cause of worldwide blindness. In the last granting period significant progress was made in characterizing damage to fiber cell membranes, the distribution of crystallins in fiber cell cytoplasm and unique spherical particles containing a core of cytoplasm covered by multiple lipid bilayers, termed multi-lamellar bodies. Noteworthy contributions were made to the field by providing theoretical analyses of the predicted scattering from each type of cellular damage. These studies have led to an important modification to commonly held proposal that nuclear cataracts are caused by protein clumping into high molecular weight aggregates. Our results suggest that the fiber cell ultrastructure of early stage nuclear cataracts is nearly identical to aged transparent lenses, suggesting that initial protein modifications and associations are part of the natural aging process. Only after extensive protein modification in advanced cataracts from India, has it been possible to identify potential HMW aggregates using electron tomography. Our results suggest that multi-lamellar bodies make a major contribution to forward scatter that interferes with normal image formation at the fovea and this contribution to visual impairment increases with age and accumulation of cell damage caused mainly by oxidative stress. We propose to expand our ultrastructural studies employing scanning and transmission electron microscopy, electron tomography, cryo-electron microscopy and confocal/multi-photon light microscopy to characterize cellular damage in a variety of nuclear cataracts that can be compared to age-related nuclear cataracts. Improved preservation and resolution will yield valuable new information about the age-related transformations of crystallins and their associations with membranes. Quantitative structural data will be analyzed theoretically to evaluate their predicted contribution to lens scattering. Ou recent evidence shows, for the first time, that autophagy and mitophagy occur in the lens and that autophagy is most likely the source of multi-lamellar bodies. We propose to explore multi-lamellar body formation in humans of varying ages and in chick embryonic lenses as an animal model that will allow identification and regulation of genes involved in autophagy. Autophagy is enhanced by nutritional stress that could be important during early lens development. These ultrastructural studies and theoretical analyses are expected to lead to better understanding of the mechanisms of cell damage that produce excessive light scattering in nuclear cataract formation.