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

项目概要/摘要 正如RFA的高优先级研究主题所述，有令人信服的证据表明， 糖基化在AD的早期发病机制和进展中起着关键作用， "这些分子作为生物标志物和疾病干预靶点的潜力仍然存在。 大部分未开发”。计划相关的具体领域包括"细胞外 基质和蛋白聚糖在AD相关病理学中的累积"。这些地区 我的实验室最近探索的主题，我的团队参与了建立 硫酸乙酰肝素修饰的蛋白质的生物学功能在过去的20年。在最近的工作中 我们已经表明硫酸乙酰肝素蛋白聚糖调节膜运输，包括 自噬、内吞作用和线粒体监视（1）， 神经变性病理学我们已经证明硫酸乙酰肝素的适度变化 结构，如硫酸化状态或链长，可以增加分解代谢膜运输， 包括将自噬体递送至溶酶体。这些发现表明， 硫酸乙酰肝素结构可以抵消AD中受损的细胞过程 和相关的病理学。这一假设得到了我们的证明， 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 在三种不同的神经退行性疾病（包括AD）的果蝇模型中（2）。是 重要的是要指出，这些变化的水平不会破坏发育模式 但实际上赋予了增加的寿命和抗氧化应激性。使用一组 CRISPR产生的突变体人类细胞系影响硫酸乙酰肝素生物合成， 表明这些分子对膜运输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AD的医学相关模型中， 确定硫酸乙酰肝素生物合成是否是AD及相关疾病的可行治疗靶点 病理学这些研究采用了在已知AD中携带突变的iPSC衍生的神经元， 易感基因（早老素和APP），和果蝇模型的年龄依赖性 神经变性，其中在成人中实现早老素功能的条件性敲低 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是否 通过靶向敲低关键生物合成酶编码基因实现的生物合成可以 实现细胞表型的拯救，并逆转自噬、线粒体自噬和 已经在人体组织以及iPSC衍生的细胞中观察到的膜运输 患者的神经元。

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.