Assessment of a novel tau propagation pathway from layer II medial entorhinal cortical neurons to CA1 pyramidal neurons as an early Braak stage mouse model

异常磷酸化微管相关蛋白tau(p-tau)是AD的诊断标志之一 病理，这与阿尔茨海默病的突触丢失和认知能力下降密切相关。陶氏病理学先行 出现在经嗅觉皮质和内嗅觉皮质第二层(EC II)，然后扩散到羊角 阿尔茨海默病前驱期(Braak分期I-II)海马区CA1区。然而，没有动物 模型曾经成功地显示了从EC II到CA1的tau传播，这在早期通常可以看到 布拉克舞台剧。最近的一项研究发现，EC II中Wolfram综合征-1(Wfs1)阳性细胞投射到 CA1通过腔隙分子层沿颞氨(TA)途径分布。我们假设 错误折叠的tau通过TA途径从EC II中的Wfs1细胞增殖到CA1，TA途径是一种 在前驱AD阶段抑制tau增殖的新治疗靶点。我们令人兴奋的初步数据 结果表明，立体定向注射表达Cre诱导的P301L tau的腺相关病毒到EC II Wfs1-Cre小鼠：1)人tau从EC II到CA1锥体神经元的强大转移，2)直接tau Wfs1 EC II神经元轴突终末与CA1锥体神经元树突之间的传递，3) 抑制CA1区锥体神经元的兴奋性；4)损害联想工作记忆。因此，这一点 新的小鼠模型可能会概括tau的病理过程，从Braak I到II，并发展 神经生理功能障碍和海马区学习障碍。此当前应用程序的对象 是为了全面描述EC II-CA1 tau繁殖小鼠模型的病理特征，并描绘 从EC II到CA1的tau连通性和传输方式。我们的首要目标是发明疗法 使用此小鼠模型的前驱AD。在目标1中，我们将：1)描述翻译后的修饰 使用多种p-tau抗体和神经元特异性标记物研究EC II-CA1小鼠的tau和细胞类型。二)验证 早期Braak分期和年龄/性别匹配在人类AD脑组织中的可译性 对照标本。iii)研究在EC、CA1和前额叶皮质区域的基因表达谱 为了了解雄性和雌性小鼠性二型性的分子基础在行为结果中的作用。在……里面 目标2，我们将使用免疫电子显微镜和超分辨率共聚焦显微镜成像来 捕获EC II轴突终末与CA1区锥体神经元放射状树突之间的tau转移；ii)探索 Cre依赖的互补示踪CA1锥体细胞和EC II神经元之间的单突触 改良狂犬病病毒和WGA-GFP报告系统的作用，以及iii)确定激活/抑制效果 神经元放电对tau增殖、神经元胞外囊泡释放的作用及其与低密度脂蛋白受体的关系 蛋白1是预测的突触终末分泌的游离tau的受体。拟议的研究 该项目将对在Braak早期阶段看到的tau传播机制和 为认知表型中的性别二形性提供了新的视角。

Abnormally phosphorylated microtubule-associated protein tau (p-tau) is one of the diagnostic hallmarks of AD pathologies, which strongly correlates with synaptic loss and cognitive decline in AD. Tau pathology first appears in the transentorhinal cortex and entorhinal cortex layer II (EC II), then spreads to the Cornu Ammonis 1 (CA1) field of the hippocampal region at the prodromal stage of AD (Braak stage I-II). However, no animal model has ever succeeded in showing tau propagation from EC II specific to CA1 as typically seen in the early Braak staging. A recent study has discovered that Wolfram syndrome-1 (Wfs1) positive cells in EC II project to CA1 via the stratum lacunosum moleculare along the temporammonic (TA) pathway. We hypothesize that misfolded tau propagates from Wfs1+ cells in EC II to CA1 via the TA pathway, and that the TA pathway is a novel therapeutic target to suppress tau propagation in the prodromal AD stage. Our exciting preliminary data showed that the stereotaxic injection of adeno-associated virus expressing Cre-inducible P301L tau into EC II of Wfs1-Cre mice induced: 1) robust human tau transfer from EC II to CA1 pyramidal neurons, 2) direct tau transfer between axonal terminals of Wfs1+ EC II neurons and dendrites of CA1 pyramidal neurons, 3) suppression of excitability of CA1 pyramidal neurons, and 4) impaired associative working memory. Thus, this new mouse model may recapitulate tau pathology progression from Braak I to II, and develop neurophysiological dysfunction and hippocampal learning impairment. The object of this current application is to fully characterize the pathology of this EC II-CA1 tau propagation mouse model and delineate the connectivity and mode of tau transmission from EC II to CA1. Our overarching goal is to invent therapeutics for prodromal AD using this mouse model. In Aim 1, we will i) characterize the post-translational modification of tau and cell types in EC II-CA1 mice using multiple p-tau antibodies and neuronal specific markers. ii) Validate the translatability of the findings in human AD brain tissues using early Braak stage and age/sex matched control specimens.iii) Investigate the gene expression profiles in EC, CA1, and prefrontal cortical regions of male and female mice to understand the molecular basis of sexual dimorphism in the behavioral outcome. In Aim 2, we will i) employ immuno-electron microscopy and super-resolution confocal microscopic imaging to capture tau transfer between EC II axonal terminals and radial dendrites of CA1 pyramidal neurons;ii) explore monosynaptic tracing between CA1 pyramidal cells and EC II neurons using Cre-dependent complementation of a modified rabies virus and WGA-GFP reporter system, and iii) determine the effect of activating/inhibiting neuronal firing on tau propagation, the role of neuronal extracellular vesicle release, and LDL Receptor Related Protein 1 as the predicted receptor for free tau secreted from the synaptic terminals. The proposed research project will develop a new understanding of tau propagation mechanism seen in the early Braak stages and provide a new insight for the sexual dimorphism in cognitive phenotype.