AD LENS PATHOLOGY: BIOCHEMISTRY & DIAGNOSTIC IMAGING

描述(由申请人提供)：这一新的研究者应用程序的目标是研究阿尔茨海默病(AD)在大脑和眼晶状体中的发病机制。老年性脑内B-淀粉样蛋白(AB)积聚是阿尔茨海默病的主要特征。我们最近在人类晶状体中发现了AB，并在老年性AD患者的晶状体中检测到AB沉积、淀粉样病理学和共定位的赤道上核上白内障(SNC)，但在那些没有这种疾病的人中没有检测到。由于这些不寻常的白内障位于虹膜后面的晶状体周围，这种表型既不是视觉障碍，也不是常规检查可以观察到的。我们在Tg2576 AD转基因小鼠晶状体中发现了类似的SNC和人AB过表达。AB定位于晶状体纤维细胞质，在那里与胞浆晶状体蛋白相互作用，如AB-晶体蛋白，这是一种丰富的晶状体结构蛋白/分子伴侣，在AD脑中上调。AB促进金属依赖的晶状体蛋白聚集和光散射。这一数据支持一种模型，在该模型中，AIS介导的晶状体蛋白聚集增加了核上光散射，最终表现为白内障。我们推测，SNC表型及其分子先兆可能是AD疾病过程的早期、器官特异性表达。为了研究这一假说，我们将对AB介导的晶状体蛋白聚集进行生化分析，并研究将晶状体AI5作为推测的AD生物标志物进行体内非侵入性监测的可能性。拟议的研究将利用体外模型系统、体外人类AD晶状体和Tg2576转基因小鼠。目的1验证晶状体AB堆积与晶状体蛋白聚集、光散射和生物金属堆积相关的假说。我们将测定AB和生物金属在人类AD/对照组和Tg2576/WT小鼠晶状体中的浓度、定位和组成。目的2验证AB与其他晶状体蛋白相互作用通过金属蛋白氧化还原反应促进蛋白质聚集的假说。我们将研究AB与胞浆结构蛋白(a-、b-和y-晶体蛋白)的结合，并研究在AB物种、金属螯合剂和气体(空气、02、Ar)存在下晶状体蛋白的聚集。目的3验证AB介导的晶状体蛋白聚集可能作为外周可及的AD生物标志物的假设。我们将构建专门的光学仪器，用于定量、非侵入性的体内检测AB相关晶状体蛋白聚集。我们将利用这些仪器在体外检测AD/非AD晶状体和体内Tg2576/WT小鼠。我们将对四组小鼠(Tg2576、Ctrl/-铜缺失敲除、Tg2576 x Ctrl/-杂交、WT对照)的晶状体蛋白质聚集进行体内纵向评估，并将晶状体测量指数与年龄、晶状体/脑AB负荷、金属浓度和组织病理学相关联。由此得到的数据可能为AD相关蛋白充气的基本机制提供见解，并支持新的AD诊断和监测技术的发展。

DESCRIPTION (provided by applicant): The goal of this new-investigator application is to study Alzheimer's disease (AD) pathogenesis in the brain and ocular lens. Age-dependent cerebral B-amyloid (AB) accumulation is a cardinal feature of Alzheimer's disease. We have recently identified AB in human lenses and detected AB deposition, amyloid pathology, and co-localizing equatorial supranuclear cataracts (SNC) in lenses from aged individuals with AD but not in those without the disorder. Because these unusual cataracts are located at the lens periphery behind the iris, this phenotype is neither visually disabling nor observable by routine examination. We have identified similar SNC and human AB overexpression in Tg2576 AD transgenic mouse lenses. AB localizes to the lens fiber cell cytoplasm, where this peptide interacts with cytosolic lens proteins such as AB-crystallin, an abundant lens structural protein/molecular chaperone that is upregulated in AD brain. AB promotes metal-dependent lens protein aggregation and light scattering. This data supports a model in which AIS-mediated lens protein aggregation increases supranuclear light scatter that ultimately manifests as cataracts. We hypothesize that the SNC phenotype and its molecular antecedents may be detectable as an early, organ-specific expression of the AD disease process. To investigate this hypothesis, we will conduct biochemical analyses of AB-mediated lens protein aggregation and examine the potential for non-invasive in vivo monitoring of lens AI5 as a putative AD biomarker. The proposed studies will utilize in vitro model systems, ex vivo human AD lenses, and Tg2576 transgenic mice. Aim 1 tests the hypothesis that lens AB accumulation is associated with localized lens protein aggregation, light scattering, and biometal accumulation. We will determine AB and biometal concentrations, localization, and composition in human AD/control and Tg2576/WT mice lenses. Aim 2 tests the hypothesis that AB interacts with other lens proteins to promote protein aggregation via metalloprotein redox reactions. We will investigate AB binding to cytosolic structural proteins (a-, b-, and y-crystallins) and study lens protein aggregation in the presence of AB species, metal chelators, and gases (air, 02, Ar). Aim 3 tests the hypothesis that AB-mediated lens protein aggregation may serve as a peripherally-accessible AD biomarker. We will construct purpose-built optical instruments for quantitative, non-invasive in vivo detection of AB-associated lens protein aggregation. We will utilize these instruments to examine AD/non-AD lenses ex vivo and Tg2576/WT mice in vivo. We will conduct a longitudinal in vivo assessment of lens protein aggregation in four groups of mice (Tg2576, Ctrl+/- Cu-deficit knockouts, Tg2576 x Ctrl+/- crosses, WT controls) and correlate index lens measurements with age, lens/brain AB burden, metal concentration, and histopathology. The resulting data may provide insights into fundamental mechanisms of AD-associated protein aeration and support development of novel AD diagnostic and monitoring technology.