Targeting emerging P2RX7 signaling pathways in animal models of Alzheimer's disease

神经原纤维缠结，由过度磷酸化的tau蛋白的细胞内聚集体组成，到目前为止 最相关的病理与阿尔茨海默病(AD)的临床症状。新出现的证据表明 细胞外小泡(EV)，如外周小体和微泡，转移病理性tau蛋白 以细胞间为载体，在不同的脑区传播tau病理。当务之急是 寻找脑源性EV的分子基础，它关键地调节致病菌的运输和摄取 神经细胞间的tau蛋白和受体神经元中tau蛋白的聚集。 目前应用的目的是阐明嘌呤能受体P2RX7对EV-1的作用。 介导型tau的繁殖。我们的初步数据显示，抑制GSK分泌的小胶质细胞EV 1482160化合物是一种P2RX7的特异性抑制剂，它显著减少了tau在CA1和CA3中的聚集 锥体神经细胞和齿状颗粒细胞与P301S结节病动物模型。有趣的是，这 结合减少外体特异性的“运输所需的内体分选复合体”(ESCRT) EV标志物TSG101在相同的海马区，提示EV可能来自小胶质细胞 到海马神经元，这可能转移和种子错误折叠的tau，并加速蛋白质在 接收神经元。因此，这些数据表明了P2RX7对EV介导的tau的调节机制。 推广和确定了P2RX7抑制剂对AD或其他脊椎病的治疗潜力。我们 假设P2RX7关键调控EV在小胶质细胞和脑内神经元之间的转移 海马神经元，从而促进错误折叠的tau的扩散。我们将验证其效果 GSK1482160通过在P301S tau小鼠中使用P2rx7缺失来概括这些发现 以腺相关病毒(AAV)为基础的tau繁殖小鼠模型。 在目标1中，我们将确定系统缺失P301S小鼠的P2rx7基因的效果。分布情况： 将对海马区的EV标记物和tau病理进行评估，并与结果进行比较。 来自GSK1482160-P301S小鼠。在目标2中，我们将确定P2RX7对分泌的影响 以及EV和EV相关tau的转移及其体外聚集能力。这将确定哪个单元格 Type尤其对P2RX7调控的tau扩散到海马神经元负责。在《目标3》中，我们将 确认目标2中选择的用于将EVS输出到海马神经元的细胞类型- 特异性缺失外切体合成分子P2rx7或Tsg101，并验证P2RX7是否介导EV 使用基于AAV的tau繁殖小鼠模型，分泌物负责tau的繁殖。成功 这项研究的完成将加强我们对神经胶质细胞分泌EVS的分子的了解 体外和体内对神经元的作用，并确定AD的新靶点。

Neurofibrillary tangles, composed of intracellular aggregates of hyperphosphorylated tau protein are by far the most correlated pathology with clinical symptoms of Alzheimer disease (AD). Emerging evidence suggests that extracellular vesicles (EVs), such as exosomes and microvesicles, transfer pathological tau protein between cells as vehicles, and propagate tau pathology in different brain regions. It is urgently important to find the molecular basis of brain-derived EV, which critically regulates the transport and uptake of pathogenic tau protein between neuronal cells and aggregation of tau protein in recipient neurons. The purpose of the current application is to delineate the effect of P2RX7, a purinergic receptor, on EV- mediated tau propagation. Our preliminary data have shown that suppressing microglial EV secretion by GSK 1482160 compound, a specific inhibitor of the P2RX7, dramatically reduces tau aggregation in CA1 and CA3 pyramidal neuronal cells and dentate granular cells with P301S tauopathy animal model. Interestingly this coalesces with reduction of exosome-specific ‘endosomal sorting complexes required for transport’ (ESCRT) EV marker, TSG101, in the same hippocampal regions, suggesting the possible EV trafficking from microglia to hippocampal neurons, which may transfer and seeds misfolded tau and accelerate protein aggregation in receiving neurons. Thus, those data indicate the regulatory mechanism by P2RX7 on EV mediated tau propagation and posit the therapeutic potential of the P2RX7 inhibitor for AD or other tauopathy. We hypothesize that P2RX7 critically regulates the transfer of EVs between microglia and neurons in the hippocampal neurons, thereby facilitate spreading misfolded tau. We will validate the effect of GSK1482160 on tau propagation by recapitulating those findings using P2rx7 deletion in P301S tau mice and adeno-associated virus (AAV)-based tau propagation mouse model. In Aim 1, we will determine the effect of systemic deletion of P2rx7 in P301S mouse. The distribution of EV markers and tau pathology in the hippocampal regions will be evaluated and compared with the findings from GSK1482160-administered P301S mice. In Aim 2, we will determine the effect of P2RX7 on secretion and transfer of EV and EV-associated tau and its aggregation potency in vitro. This will determine which cell type is particularly responsible for P2RX7 regulated tau spread into hippocampal neurons. In Aim 3, we will confirm the cell type, which is selected in Aim 2, for the export of EVs into hippocampal neurons by cell type- specific deletion of P2rx7 or Tsg101, an exosome synthesis molecule, and validate if P2RX7-mediated EV secretion are responsible for tau propagation using AAV-based tau propagation mouse model. Successful completion of this study will enhance our understanding of molecules that mediates secretion of EVs from glia to neurons in vitro and in vivo, and identify novel targets for AD.