Alpha-Crystallin and Cataractogensis

描述(由申请人提供)： 这些建议的长期目标是更好地了解人类晶状体随着年龄的增长而发生的生化和生物物理变化，这些变化最终会导致白内障。拟议的研究将集中在α-晶体蛋白上。除了是晶状体中负责产生所需折射的结构蛋白的关键成员外，α-晶状体蛋白还是一种分子伴侣。在这种能力下，它有助于抑制可能导致散射和白内障的蛋白质的非特异性聚集，α-β-晶体蛋白是小热休克蛋白家族的成员，也参与许多年龄相关性神经/眼部疾病，包括积聚在老年性黄斑变性患者视网膜色素上皮下的细胞外沉积(玻璃体)。拟议的研究将提供新的数据，这将有助于实现显著延缓衰老依赖型白内障形成的最终目标。 具体目标是：1.结构和功能研究。各种突变和化学物质 将利用冷冻电子显微镜和电子自旋共振定点自旋标记等技术来研究α-晶状体蛋白的修饰及其对伴侣功能的影响。2.研究大分子拥挤对蛋白质结构和稳定性的影响。这些研究涉及到这样一个事实，即天然晶状体中的大分子浓度极高(500 mg/ml)，可能会对蛋白质的结构、功能和稳定性产生重大影响。到目前为止，这个问题从未得到解决。3.将详细研究α-晶状体蛋白基因敲除小鼠的动物模型，以及一种新的涉及α-晶状体蛋白和γ-晶状体蛋白的小鼠白内障。这些都是了解与年龄相关的人类白内障中发生的生化和生物物理变化的极佳模型。

DESCRIPTION (provided by applicant): The long-term objectives of these proposals are to better understand the biochemical and biophysical changes that occur in the human lens with aging, and which ultimately lead to cataract. The proposed studies will focus on alpha-crystallin. In addition to being a key member of the structural proteins in the lens that are responsible for producing the needed refraction, a-crystallin is a molecular chaperone. In this capacity it helps suppress non-specific aggregation of proteins that may cause scattering and cataract, alphaBeta-crystallin, a member of the small heat-shock protein family is also involved in many age-dependent neurological/eye diseases including extracellular deposits (Drusen) that accumulate below the retinal pigment epithelium of patients with age-related macular degeneration. The proposed studies will provide new data that will be useful for achieving the ultimate goal of significantly retarding the formation of aging dependent cataract. The specific aims are: 1. Structural and functional studies. Various mutations and chemical modifications of alpha-crystallin and their effect on chaperone function will be studied with technologies such as cryo-electron microscopy and site-directed spin-labeling with electron spin resonance. 2. Studies on the effects of macromolecular crowding on protein structure and stability in the lens. These studies deal with the fact that the macromolecular concentrations in the native lens are extremely high (500 mg/ml) and may have dramatic effects on proteins structure, function, and stability. This problem has never been addressed thus far. 3. Animal models of cataract, alpha-crystallin knock-out mouse, as well as a new mouse cataract that involves a and gamma-crystallin will be studies in detail. These are excellent models for understanding the biochemical and biophysical changes that occur in age-related human cataract.