The influence of Kallikrein-8 on Alzheimer disease-related neuroplasticity defects and tauopathy

Kallikrein-8 对阿尔茨海默病相关神经可塑性缺陷和 tau 蛋白病变的影响

• 批准号: 396157641
• 负责人: Privatdozent Dr. Arne Herring
• 金额: --
• 依托单位: Institut für Neuropathologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/396157641?language=en
• 关键词: influence; Kallikrein; Alzheimer; disease; related

We previously identified Kallikrein-8 (KLK8) as a potential key player in the pathogenesis of Alzheimer disease (AD). We could detect excessive KLK8 mRNA and protein levels at incipient stages of AD, in both AD-affected and scarcely-affected brain areas of AD patients and transgenic (Tg) CRND8 mice. Moreover, we could show that short-term inhibition of cerebral KLK8 (for only four weeks) by an anti-KLK8 antibody at a moderate disease stage was sufficient to mitigate multiple features of Alzheimer pathology in Tg mice. Independent studies have shown that KLK8 modulates structural and electrochemical neuroplasticity by substrate turnover (processing of EPHB2, L1-CAM, neuregulin-1, fibronectin), modulation of synaptic tagging processes or by complex formation with binding partners such as PEBP-1. All of the aforementioned KLK8 interaction partners are also involved in AD. Work of our own lab has shown that KLK8 blockade in Tg brain increases expression of plasticity-controlling molecules, dendritic spine density and dendritic complexity, ultimately improving memory in Tg mice. The microtubule-associated protein tau, involved both in AD-related neurodegeneration and structural plasticity, is also connected to KLK8 signaling. Ligand-mediated activation of the KLK8 substrate EPHB2 inhibits tau hyper-phosphorylation, whereas the KLK8 down-stream target FKBP5 provokes tau oligomerization and accelerates neurotoxicity. Work in our own lab demonstrated that KLK8 inhibition protected EPHB2 from degradation and reduced tau pathology in Tg mice. With the present proposal we first aim to verify the therapeutic potential of KLK8 inhibition in AD. Therefore, we will genetically and permanently reduce KLK8 expression in Tg mice by crossbreeding with KLK8-knockdown mice, followed by behavioral phenotyping (spatial and recognition memory, agitation and anxiety) and quantification of amyloid beta pathology. Second, we will focus on the role of KLK8 in AD-related neuroplasticity disturbances. Accordingly, we will examine the in vivo and in vitro effects of short-term KLK8 inhibition, permanent KLK8 reduction or induction of KLK8 on neuronal proliferation, differentiation, and survival, dendritic complexity and spine density, as well as on KLK8 substrate turnover, synaptic tagging and complex-formation. Third, we will investigate the function of KLK8 in tau metabolism and therefore test the in vivo and in vitro effects of KLK8 inhibition, KLK8 reduction and KLK8 induction on physiologic and pathologic tau phosphorylation, intraneuronal tau distribution, and on tau-modulating EPHB2-dependent and EPHB2-independent signaling pathways. This project has the potential to verify KLK8 as a therapeutic target against AD and to gain new mechanistic insights in the interplay between KLK8, neuroplasticity and tau metabolism.

我们以前确定激肽释放酶-8（KLK 8）是阿尔茨海默病（AD）发病机制中的潜在关键因素。我们可以检测到过量的KLK 8的mRNA和蛋白水平在AD的初期阶段，在AD患者和转基因（Tg）CRND 8小鼠的AD影响和很少影响的脑区。此外，我们可以表明，在中度疾病阶段通过抗KLK 8抗体对脑KLK 8的短期抑制（仅四周）足以减轻Tg小鼠中阿尔茨海默病病理学的多种特征。独立研究表明，KLK 8通过底物转换（EPHB 2、L1-CAM、神经调节蛋白-1、纤连蛋白的加工）、调节突触标记过程或通过与结合伴侣（如PEBP-1）形成复合物来调节结构和电化学神经可塑性。所有上述KLK 8互动伙伴也参与了AD。我们自己实验室的工作表明，Tg大脑中的KLK 8阻断增加了可塑性控制分子的表达，树突棘密度和树突复杂性，最终改善了Tg小鼠的记忆力。微管相关蛋白tau参与AD相关的神经变性和结构可塑性，也与KLK 8信号传导有关。配体介导的KLK 8底物EPHB 2的活化抑制tau过度磷酸化，而KLK 8下游靶标FKBP 5引起tau寡聚化并加速神经毒性。在我们自己的实验室中的工作表明，KLK 8抑制保护EPHB 2免于降解并减少Tg小鼠中的tau病理。通过本提议，我们首先旨在验证KLK 8抑制在AD中的治疗潜力。因此，我们将通过与KLK 8基因敲除小鼠杂交，在遗传上永久性地降低Tg小鼠中KLK 8的表达，然后进行行为表型分析（空间和识别记忆，激动和焦虑）和淀粉样蛋白β病理学的定量。其次，我们将重点关注KLK 8在AD相关神经可塑性障碍中的作用。因此，我们将研究短期KLK 8抑制、永久性KLK 8减少或KLK 8诱导对神经元增殖、分化和存活、树突复杂性和棘密度以及对KLK 8底物周转、突触标记和复合物形成的体内和体外影响。第三，我们将研究KLK 8在tau代谢中的功能，并因此测试KLK 8抑制、KLK 8减少和KLK 8诱导对生理和病理性tau磷酸化、神经元内tau分布以及tau调节EPHB 2依赖性和EPHB 2非依赖性信号通路的体内和体外影响。该项目有可能验证KLK 8作为AD的治疗靶点，并获得KLK 8、神经可塑性和tau代谢之间相互作用的新机制见解。