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

梅奥诊所杰克逊维尔-分包 项目总结 由淀粉样蛋白β(Aβ)和含有过度磷酸化的神经原纤维缠结组成的淀粉样斑块 Tau是阿尔茨海默病(AD)的病理特征。最近的研究表明，这些病理性的 损伤可能通过跨突触机制从一个脑区逐渐扩散到另一个脑区。这个 项目3的主要目标是剖析促进或抑制Aβ/tau的分子和细胞通路 传播的具体焦点是神经元受体LRP1和硫酸乙酰肝素蛋白多糖(HSPG)。作为 载脂蛋白E基因的ε4等位基因是晚发性阿尔茨海默病的最大遗传风险因素，我们将 还要评估载脂蛋白E异构体对Aβ/tau扩散的特定影响，以及这些影响是否取决于 神经元LRP1/HSPG的存在。在前一个供资周期中，项目3确定了apoE的作用 脑Aβ代谢中的异构体和载脂蛋白E受体LRP1和HSPG，确立LRP1的相反作用 (有益)和热休克蛋白(有害)在脑Aβ代谢中，以及载脂蛋白E亚型的调节作用。 HSPG被认为可以促进tau的病理性扩散。重要的是，我们在 与项目1(Holtzman，PI)的合作也证明了LRP1在细胞摄取tau方面的作用 单体和聚集体。此外，我们还检测到载脂蛋白E亚型依赖于tau介导的效应。 小鼠的行为缺陷，从而在相关的致病途径中将Aβ、tau、apoE、lrp1和hspg联系在一起。因此， 我们假设LRP1抑制而HSPG促进病理性传播的速度和程度 Aβ和tau聚合体的结合，并且apoE进一步以异构体特异性的方式调节这些事件。 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LRP1和 利用条件性小鼠模型，热休克蛋白调节A、β和tau聚集体在体内的病理性扩散。我们 还将讨论淀粉样蛋白病变的存在如何影响tau病理和在LRP1-或 HSPG依赖的方式，在目标2中，我们将分析apoE亚型如何调控HSPG的病理性传播 Tau聚集体以及是否有任何apoE效应依赖于LRP1、HSPG或淀粉样蛋白病理的存在。 有条件的小鼠模型以及病毒介导的载脂蛋白E亚型的表达将在这些 学习。在目标3中，我们将剖析lrp1、hspg和apoE亚型调控细胞的机制。 Aβ和Tau的各种聚集形式的贩运、降解或积累。小鼠初级神经元， 诱导多能干细胞(IPSC)来源的人类神经元以及微流控平台将用于 这些研究。与其他PPG项目的互动将包括评估神经元活动和 LRP1/HSPG/apoE依赖的Aβ/tau扩散上的睡眠/觉醒周期。该项目将使用病毒载体核心 用于体内和体外研究的AAV和慢病毒载体的生产。总而言之，这些研究应该 对Aβ/tau传播的分子机制产生关键的洞察力，并为 对抗阿尔茨海默病和其他神经退行性疾病的机制疗法。

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.