Neuronal LRP1 and HSPG in Pathological Spreading of A-Beta and Tau

马约杰克逊维尔-分包合同 项目摘要 淀粉样斑块由β淀粉样蛋白（Aβ）和神经元缠结组成， tau蛋白是阿尔茨海默病（AD）的病理学标志。最近的研究表明，这些病理 病变可能通过跨突触机制从一个脑区域逐渐扩散到另一个脑区域。的 项目3的主要目标是剖析促进或抑制Aβ/tau蛋白的分子和细胞途径 特别关注神经元受体LRP 1和硫酸乙酰肝素蛋白聚糖（HSPG）。为 载脂蛋白E基因（APOE 4）的ε4等位基因是晚发性AD最强的遗传危险因素，我们将 还评估apoE亚型对Aβ/tau扩散的特异性作用，以及这种作用是否取决于 神经元LRP 1/HSPG的存在。在上一个供资周期，项目3确定了apoE的作用 同种型和apoE受体LRP 1和HSPG在脑Aβ代谢中的作用，建立LRP 1的相反作用 在脑Aβ代谢中，HSPG（有益）和HSPG（有害），以及apoE亚型的调节作用。 HSPG已被认为促进tau的病理性扩散。重要的是，我们的初步研究 与项目1（Holtzman，PI）的合作也证明了LRP 1在tau的细胞摄取中的作用 单体和聚集体。此外，我们已经检测到apoE亚型依赖性的tau介导的 行为缺陷，从而将Aβ、tau、apoE、LRP 1和HSPG与相关致病途径联系起来。因此，在本发明中， 我们假设LRP 1抑制而HSPG促进病理扩散的速度和程度， apoE以同种型特异性方式进一步调节这些事件。 我们提出了三个具体目标来解决我们的假设。在目标1中，我们将研究神经元LRP 1和 使用条件小鼠模型，HSPG在体内调节Aβ和tau聚集体的病理性扩散。我们 还将讨论淀粉样蛋白病理学的存在如何影响tau病理学和在LRP 1-或 目的2：分析apoE亚型如何调节HSPG依赖性的病理扩散。 tau聚集体以及任何apoE效应是否取决于LRP 1、HSPG或淀粉样病变的存在。 条件小鼠模型以及apoE同种型的病毒介导的表达将用于这些研究。 问题研究在目的3中，我们将剖析LRP 1，HSPG和apoE亚型调节细胞凋亡的机制， Aβ和tau的各种聚集形式的运输、降解或积累。小鼠初级神经元， 诱导多能干细胞（iPSC）衍生的人类神经元以及微流体平台将用于 这些研究。与其他PPG项目的互动将包括评估神经元活动的影响， 睡眠/觉醒周期对LRP 1/HSPG/apoE依赖性Aβ/tau扩散影响该项目将使用病毒载体核心来 用于体内和体外研究的AAV和慢病毒载体的生产。总之，这些研究应该 对Aβ/tau扩散的分子机制产生重要见解，并为以下方面的策略提供信息： 基于机制的治疗，以对抗AD和其他具有tau蛋白病的神经退行性疾病。

MAYO CLINIC JACKSONVILLE - Subcontract PROJECT SUMMARY The amyloid plaques composed of amyloid-β (Aβ) and neurofibrillary tangles containing hyperphosphorylated tau are pathological hallmarks of Alzheimer’s disease (AD). Recent studies have shown that these pathological lesions progressively spread from one brain region to another likely through a trans-synaptic mechanism. The major goal of Project 3 is to dissect the molecular and cellular pathways that either promote or inhibit Aβ/tau spreading with a specific focus on neuronal receptors LRP1 and heparan sulfate proteoglycan (HSPG). As the ε4 allele of the apolipoprotein E gene (APOE4) is the strongest genetic risk factor for late-onset AD, we will also evaluate the apoE isoform-specific effects on Aβ/tau spreading and whether such effects depend on the presence of neuronal LRP1/HSPG. During the previous funding cycle, Project 3 has defined the roles of apoE isoforms and apoE receptor LRP1 and HSPG in brain Aβ metabolism, establishing the opposing roles of LRP1 (beneficial) and HSPG (harmful) in brain Aβ metabolism, as well as the modulatory effects of apoE isoforms. HSPG has been suggested to promote pathological spreading of tau. Importantly, our preliminary studies in collaboration with Project 1 (Holtzman, PI) have also demonstrated a role of LRP1 in cellular uptake of tau monomer and aggregates. Further, we have detected an apoE isoform-dependent effects on tau-mediated behavioral deficits in mice, thus linking Aβ, tau, apoE, LRP1 and HSPG in related pathogenic pathways. Thus, we hypothesize that LRP1 inhibits and HSPG promotes the speed and extent of pathological spreading of Aβ and tau aggregates, and that apoE further modulates these events in an isoform-specific manner. We propose three specific aims to address our hypothesis. In Aim 1, we will examine how neuronal LRP1 and HSPG modulate pathological spreading of Aβ and tau aggregates in vivo using conditional mouse models. We will also address how the presence of amyloid pathology impacts tau pathology and spreading in an LRP1- or HSPG-dependent manner, In Aim 2, we will analyze how apoE isoforms modulate pathological spreading of tau aggregates and whether any apoE effects depend on the presence of LRP1, HSPG, or amyloid pathology. Conditional mouse models as well as viral mediated expression of apoE isoforms will be employed in these studies. In Aim 3, we will dissect the mechanisms by which LRP1, HSPG and apoE isoforms regulate cellular trafficking, degradation or accumulation of various aggregated forms of Aβ and tau. Mouse primary neurons, induced pluripotent stem cell (iPSC)-derived human neurons, as well as microfluidic platform will be used for these studies. Interactions with other PPG projects will include evaluating the effects of neuronal activities and sleep/wake cycle on LRP1/HSPG/apoE-dependent Aβ/tau spreading. This project will use Viral Vector Core for the production of AAV and lentiviral vectors for in vivo and in vitro studies. Together, these studies should generate critical insights into the molecular mechanism underlying Aβ/tau spreading and inform strategies for mechanism-based therapy to combat AD and other neurodegenerative diseases with tauopathies.