Glysocaminoglycan Modifications as Regulators of Alzheimer's Disease-Related Pathologies

项目摘要/摘要 正如本RFA的高优先级研究主题所描述的那样，有令人信服的证据 糖基化在阿尔茨海默病的早期发病和进展中起着关键作用 这些分子作为生物标记物和疾病干预靶点的潜力仍然存在。 很大程度上是未被开发的“。与程序相关的特定领域包括“细胞外角色” …中的基质和蛋白多糖阿尔茨海默病相关病理的积累“。这些地区是 我的实验室最近探索的主题，我的团队参与了建立 近20年来硫酸乙酰肝素修饰蛋白的生物学功能。在最近的工作中 我们已经证明，硫酸乙酰肝素蛋白多糖调节膜转运，包括 自噬、内吞和线粒体监视(1)，是 神经退行性病理学。我们已经证明，硫酸乙酰肝素的轻微变化 结构，如硫酸盐化状态或链长，可以增加分解代谢膜的运输， 包括将自噬小体运送到溶酶体。这些发现表明，改变 硫酸乙酰肝素结构可以中和AD中受损的细胞过程 以及相关的病理学。这一假设得到了我们的论证的支持，即部分 特异性硫酸乙酰肝素修饰酶编码基因的减少可以抑制细胞损失 在包括阿尔茨海默病在内的三种不同的果蝇神经退行性疾病模型中。它是 重要的是要指出，这些变化的水平不会扰乱发展模式 但实际上可以延长寿命和抵抗氧化应激。使用一个面板 CRISPR产生的突变的人类细胞系影响硫酸乙酰肝素的生物合成 表明这些分子对膜转运的调节在人类中是保守的 细胞。我们现在希望将这些观察结果扩展到与医学相关的AD模型中，以 确定硫酸乙酰肝素生物合成是否是治疗AD及相关疾病的可行靶点 病理学。这些研究使用了两个IPSC来源的神经元，这些神经元携带已知AD的突变 易感基因(早老素和APP)与年龄依赖的果蝇模型 神经退行性变，在成人中实现有条件的早老素功能敲除 神经元。在这两个系统中，我们建议确定硫酸乙酰肝素的变化 通过靶向敲除关键生物合成酶编码基因实现的生物合成可以 实现细胞表型的挽救，逆转自噬、有丝分裂和 在人体组织和IPSC来源的细胞中观察到的膜转运 来自病人的神经元。

Project Summary/Abstract As described by the High Priority Research Topics for this RFA, there is compelling evidence that glycosylation plays “critical roles in the early pathogenesis and progression of AD” yet the “potential of these molecules to serve as biomarkers and targets of disease intervention remains largely unexplored”. Specific areas of program relevance included the “role of extracellular matrix and proteoglycans in … accumulation of AD-related pathologies”. These areas are topics my laboratory has recently explored and my group has been involved in establishing the biological functions of heparan sulfate modified proteins over the last 20 years. In recent work we have shown that heparan sulfate proteoglycans regulate membrane trafficking, including autophagy, endocytosis and mitochondrial surveillance(1), processes central to neurodegenerative pathology. We have shown that modest changes in heparan sulfate structure, such as sulfation state or chain length, can increase catabolic membrane trafficking, including delivery of autophagosomes to the lysosome. These findings suggest that changing heparan sulfate structure could counteract the cellular processes that are compromised in AD and related pathologies. This hypothesis is supported by our demonstration that partial reductions in specific heparan sulfate modifying enzyme encoding genes can suppress cell loss in three distinct Drosophila models of neurodegenerative diseases(2) including AD. It is important to point out that the level of these changes do not disrupt developmental patterning but actually confers increased lifespan and resistance to oxidative stress. Using a panel of CRISPR-generated mutant human cell lines affecting heparan sulfate biosynthesis we have shown that the regulation of membrane trafficking by these molecules is conserved in human cells. We now wish to extend these observations into medically relevant models of AD to determine if heparan sulfate biosynthesis is a viable therapeutic target for AD and related pathologies. These studies employ both iPSC-derived neurons bearing mutations in known AD susceptibility genes (presenilin and APP), and a Drosophila model of age-dependent neurodegeneration, where conditional knockdown of presenilin function is achieved in adult neurons. In both of these systems we propose to determine if changes in heparan sulfate biosynthesis achieved by targeted knockdown of key biosynthetic enzyme encoding genes can achieve rescue of cellular phenotypes, and reverse the alterations in autophagy, mitophagy, and membrane trafficking that have been observed in human tissues as well as iPSC-derived neurons from patients.