神经元内IKKbeta在Tau转基因阿尔兹海默病模型小鼠发病中的作用及机制研究

It has become a known pathogenic mechanism in Alzheimer's disease (AD) that hyperphosphorylated Tau protein (P-Tau) induces neuronal degeneration.Recent studies showed that autophagy can degrade the accumulated P-Tau in neurons and prevent AD pathogenesis. In our preliminary experiments, we observed that ablation of neuronal IKKbeta attenuated upregulation of autophagy induced by LPS. Thus, we hypothesize that neuronal IKKbeta is a protective kinase in AD. Its deficiency might inhibit autophagic clearance of P-Tau and exacerbate the disease. Our current proposal will cross-breed Tau-transgenic mice with IKKbeta-floxed mice and Camk2alpha-Cre mice, and delete IKKbeta specifically in neurons in the adult AD mice. Thereafter, we are able to investigate the preventive effects of neuronal IKKbeta on cognitive deficits, neuronal dysfunction and damaged autophagy. Additionally, we will delete IKKbeta in primary cultured tau-transgenic cortical neurons to investigate whether IKKbeta regulates autophagy-mediated p-Tau degradation. In summary, our study will contribute to a better understanding of AD pathogenic mechanisms, and clarify whether IKKbeta is a proper therapeutic target.

异常磷酸化Tau蛋白（P-Tau）诱导神经元变性是阿尔兹海默病(AD)的核心病理机制。研究表明自噬能够降解神经元内异常聚集的P-Tau，从而减缓疾病发展。我们预实验发现神经元IKKbeta缺如可降低LPS诱导的自噬增高，所以我们推测神经元IKKbeta是减缓P-Tau引起疾病进展的保护性激酶。它的缺如可能抑制神经元自噬，加剧AD小鼠的病理改变。本项目拟采用Tau转基因小鼠，与IKKbeta-floxed及神经元特异表达Cre的小鼠交配，在成年AD小鼠神经元中特异敲除IKKbeta，探讨神经元内IKKbeta对Tau转基因小鼠认知、神经元存活及自噬功能变化的影响；另外，应用原代Tau高表达皮层神经元培养结合IKKbeta敲减技术，观察IKKbeta是否调控P-Tau的自噬清除。本课题的研究有利于进一步阐明AD发病机制，并探讨IKKbeta是否为合适治疗靶点。

阿尔兹海默病是最常见的神经退行性疾病，目前仍缺乏有效的治疗方式。异常磷酸化Tau蛋白（p-Tau）诱导神经元变性是阿尔兹海默病(AD)的核心病理机制。大量研究表明自噬能够降解神经元内异常聚集的p-Tau，从而减缓疾病发展。我们前期研究发现神经元IKKbeta可调控细胞内的自噬水平，所以本课题基于前期结果进一步探讨神经元IKKbeta是否是减缓p-Tau引起疾病进展的保护性激酶。首先，我们构建AD模型，探讨敲除神经元IKKbeta对细胞氧化应激反应、细胞活性、细胞死亡及p-Tau的影响；然后，我们进一步观察神经元内DJ-1/VHL通路对IKKbeta的调控机制，以及IKKbeta敲除对细胞自噬的影响；最终明确AD模型中，自噬在IKKbeta对p-Tau及神经元坏死性凋亡影响中的作用。我们最终发现，IKKbeta可通过调控自噬减少p-Tau及坏死性凋亡介导的神经元损伤，最终改善AD的病理生理过程。本项目有利于进一步阐明AD发病机制，并探讨IKKbeta是否为合适治疗靶点提供实验依据。