Clusterin glycosylation as diagnostic and prognostic biomarker for Alzheimer's disease

项目摘要 阿糖胞苷是晚发性阿尔茨海默病（AD）的第三大主要遗传危险因素。丛生蛋白 促进可溶性淀粉样蛋白-b（Ab）穿过血脑屏障的转运。白藜芦醇结合可溶形式的 抗体，防止其聚集成淀粉样纤维。然而，血浆和血浆中的蛋白质之间没有明确的相关性。 CSF聚集蛋白浓度水平和AD，即使有大量证据表明聚集蛋白表达上调， 在AD脑中和与Ab斑块共定位。白藜芦醇是高度糖基化的，约占其质量的25% 由N-连接的聚糖组成。丛生蛋白的糖基化是受时空调控的， 作为细胞外伴侣的功能。丛生蛋白的糖基化可能在细胞凋亡中起重要作用。 与Ab的相互作用及其清除。 在这个第一阶段的项目中，我们建议开发，优化和验证一种快速和具有成本效益的质谱仪 （MS）-用于检测簇蛋白糖型的免疫测定法，其揭示完整的糖基化簇蛋白和其糖基化簇蛋白。 组成聚糖结构。我们将首先优化检测参数，如抗体量，样品体积 和稀释、捕获后冲洗、唾液酸和具有唾液酸酶的完整聚糖的酶促释放， PNGaseF酶和MS采集参数。将通过检测其 耐用性、准确性、特异性和重现性。我们将在一组匹配的CSF中使用该测定， 血浆样品（n=106）来自轻度受损和处于AD风险的健康个体。数据形式完整 聚集蛋白质量峰在血浆和CSF之间发生变化，唾液酸酶处理后样品内的质量变化， PNGaseF处理，丛生蛋白糖型的相对比率，以及ID和释放的聚糖的比率，将 在整个队列中进行比较，并与apoE基因型，apoE亚型特异性糖基化，Aβ42， 将检查Tau和pTau。 将使用第二个队列（n=100）验证第一个队列的结果。 我们的价值主张是一种快速且具有成本效益的检测方法，用于分析clusterin糖型和聚糖， 可用于评估clusterin糖基化在AD发病机制中的作用。甜菜碱糖基化可以 作为评估AD风险的生物标志物，或作为开发治疗剂的靶标， 糖基化

PROJECT SUMMARY Clusterin is the third most predominant genetic risk factor for late onset Alzheimer’s disease (AD). Clusterin facilitates the transport of soluble amyloid-b (Ab) across the blood-brain barrier. Clusterin binds soluble forms of Ab, preventing their aggregation into amyloid fibrils. However, there is no clear correlation between plasma or CSF clusterin concentration levels and AD, even though there is substantial evidence for upregulation of clusterin in the AD brain and colocalization with Ab plaques. Clusterin is heavily glycosylated, with ~25% of its mass comprised of N-linked glycans. Glycosylation of clusterin is spatially and temporally regulated, and it is important for its function as an extracellular chaperone. Glycosylation of clusterin may play an important role in the interaction with Ab and its clearance. In this Phase I project we propose to develop, optimize and validate a fast and cost-efficient mass spectrometry (MS)-immunoassay for detection of clusterin glycoforms that reveals both intact glycosylated clusterin and its component glycan structures. We will first optimize assay parameters such as antibody amount, sample volumes and dilutions, post-capture rinses, enzymatic release of sialic acids and the full glycans with sialidase and PNGaseF enzymes, and MS acquisition parameters. The assay performance will be validated by testing its robustness, accuracy, specificity, and reproducibility. We will use the assay on a cohort of matched CSF and plasma samples (n=106) from mildly impaired and healthy individuals at risk of AD. Data in the form of intact clusterin mass peaks shifts between plasma and CSF, mass shifts within samples following sialidase and PNGaseF treatment, the relative ratios of clusterin glycoforms, and IDs and ratios of the released glycans, will be compared across the cohort, and correlations with apoE genotype, apoE isoform-specific glycosylation, Aβ42, Tau and pTau will be examined. The findings from the first cohort will be validated with a second cohort (n=100). Our value proposition is a fast and cost-effective assay for analyzing clusterin glycoforms and glycans that could be utilized for evaluating the role of clusterin glycosylation in AD pathogenesis. Clusterin glycosylation could serve as a biomarker for assessing AD risk, or as a target for the development of therapeutics that modify its glycosylation.