Pathogenic events triggered by tau acetylation in neurodegenerative tauopathy

描述(申请人提供)：肌萎缩侧索硬化症是一类与年龄相关的神经退行性疾病，目前我国有数百万人患有这种疾病。Tau病的特征是tau在大脑中异常堆积，这是一种微管相关蛋白，与严重的和衰弱的认知功能障碍有关。目前，对于患有牵张症的人来说，可供选择的治疗方法有限，而且还没有治愈的方法。研究tau的致病机制对于寻找药物干预的新分子靶点至关重要。最近的证据表明，乙酰化tau(ac-tau)可能参与了tau病的发病机制，然而ac-tau是否影响潜在的认知损害的神经功能尚不清楚。我的长期目标是揭示ac-tau在神经退行性变态中的作用，为将ac-tau作为治疗认知功能障碍的新策略提供基础。目的1是确定ac-tau如何影响海马区兴奋性突触生理学。通过慢病毒基因转移，含有赖氨酸突变为谷氨酸以模拟特定残基乙酰化的人tau结构(K/Q突变体)将在活体小鼠海马神经元中表达。将在神经元上进行电生理记录，以检测突触后K/Q突变体对基础兴奋性传递和突触可塑性的影响。培养神经元记录的初步结果表明，tau微管结合区的K/Q突变导致谷氨酸能突触传递减少。目的2确定Ac-tau影响兴奋性突触后功能的分子机制。免疫细胞化学和共聚焦显微镜将被用来研究ac-tau是否异常地定位于树突棘中的兴奋性突触。此外，还将对突触后谷氨酸受体进行免疫染色，以检查K/Q突变体如何调节受体导致突触功能障碍。接下来将研究Ac-tau与突触后谷氨酸受体调节之间的特定分子相互作用。目的3建立Ac-tau在体内的致病作用。将产生一只转基因小鼠，其神经元表达人tau K/Q突变体，导致突触病理生理学(tau-K/Q小鼠)。Tau-K/Q小鼠海马区功能回路的任何异常改变都将通过兴奋性突触传递和突触可塑性的电生理记录进行监测。行为学测试将确定tau-K/Q小鼠是否会出现与tauopathy相关的学习和记忆缺陷。最后，将对老化的tau-K/Q小鼠进行组织学和生化分析，以评估大脑中的神经退行性变和tau病理。总之，该项目的结果将为了解tau在神经退行性疾病中的致病机制提供重要的见解。

DESCRIPTION (provided by applicant): Tauopathies are a class of age-related neurodegenerative diseases that millions of people in our country suffer from today. Tauopathies are characterized by the abnormal accumulation of tau, a microtubule- associated protein, in the brain which is linked to severe and debilitating cognitive dysfunction. There are currently a limited number of treatment options available for people suffering from tauopathy and there is no cure. Research to identify the mechanisms for the pathogenic effect of tau is crucial to find new molecular targets for drug intervention. Recent evidence suggests that acetylated tau (ac-tau) may contribute to pathogenesis in tauopathy, however whether ac-tau affects neuronal function underlying cognitive impairments is unknown. My long-term goal is to uncover the role of ac-tau in neurodegenerative tauopathy to provide a foundation for targeting ac-tau as a novel strategy to treat cognitive dysfunction. Aim 1 is to determine how ac-tau affects excitatory synaptic physiology in the hippocampus. Human tau constructs with lysines mutated to glutamines to mimic acetylation at specific residues (K/Q mutants) will be expressed in mouse hippocampal neurons in vivo by lentiviral-based gene transfer. Electrophysiological recordings will be performed on neurons to examine the postsynaptic effect of K/Q mutants on basal excitatory transmission and synaptic plasticity. Preliminary results from recordings of cultured neurons show that a K/Q mutant in the microtubule-binding domain of tau causes a reduction in glutamatergic synaptic transmission. Aim 2 is to determine the molecular mechanism for the effect of ac-tau on excitatory postsynaptic function. Immunocytochemistry and confocal microscopy will be used to investigate whether ac-tau is aberrantly localized at excitatory synapses in dendritic spines. Furthermore, immunostaining of postsynaptic glutamate receptors will be done to examine how the K/Q mutants modulate receptors leading to synaptic dysfunction. This will be followed by an investigation of a specific molecular interaction linking ac-tau to the regulation of postsynaptic glutamate receptors. Aim 3 is to establish the pathogenic effect of ac-tau in vivo. A transgenic mouse will be generated with neuronal expression of a human tau K/Q mutant that causes synaptic pathophysiology (tau-K/Q mice). Any abnormal modifications of the functional circuitry in the hippocampus of tau-K/Q mice will be monitored by electrophysiological recordings of excitatory synaptic transmission and synaptic plasticity. Behavioral tests will determine if tau-K/Q mice develop deficits in learning and memory associated with tauopathies. Finally, histological and biochemical analyses will be performed on aged tau-K/Q mice to evaluate neurodegeneration and tau pathology in the brain. Together, the results from this project will provide significant insight into the pathogenic mechanisms of tau in neurodegenerative disease.