eEF2K 抑制通过促进 NRF2 抗氧化反应来阻断 Aβ42 的神经毒性。

eEF2K inhibition blocks Aβ42 neurotoxicity by promoting an NRF2 antioxidant response.

机构信息

Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, Canada.

British Columbia Cancer Research Centre, 675 West 10th Avenue, Vancouver, BC, V5Z 1L3, Canada.

出版信息

Acta Neuropathol. 2017 Jan;133(1):101-119. doi: 10.1007/s00401-016-1634-1. Epub 2016 Oct 17.

Abstract

Soluble oligomers of amyloid-β (Aβ) impair synaptic plasticity, perturb neuronal energy homeostasis, and are implicated in Alzheimer's disease (AD) pathogenesis. Therefore, significant efforts in AD drug discovery research aim to prevent the formation of Aβ oligomers or block their neurotoxicity. The eukaryotic elongation factor-2 kinase (eEF2K) plays a critical role in synaptic plasticity, and couples neurotransmission to local dendritic mRNA translation. Recent evidence indicates that Aβ oligomers activate neuronal eEF2K, suggesting a potential link to Aβ induced synaptic dysfunction. However, a detailed understanding of the role of eEF2K in AD pathogenesis, and therapeutic potential of eEF2K inhibition in AD, remain to be determined. Here, we show that eEF2K activity is increased in postmortem AD patient cortex and hippocampus, and in the hippocampus of aged transgenic AD mice. Furthermore, eEF2K inhibition using pharmacological or genetic approaches prevented the toxic effects of Aβ42 oligomers on neuronal viability and dendrite formation in vitro. We also report that eEF2K inhibition promotes the nuclear factor erythroid 2-related factor (NRF2) antioxidant response in neuronal cells, which was crucial for the beneficial effects of eEF2K inhibition in neurons exposed to Aβ42 oligomers. Accordingly, NRF2 knockdown or overexpression of the NRF2 inhibitor, Kelch-Like ECH-Associated Protein-1 (Keap1), significantly attenuated the neuroprotection associated with eEF2K inhibition. Finally, genetic deletion of the eEF2K ortholog efk-1 reduced oxidative stress, and improved chemotaxis and serotonin sensitivity in C. elegans expressing human Aβ42 in neurons. Taken together, these findings highlight the potential utility of eEF2K inhibition to reduce Aβ-mediated oxidative stress in AD.

摘要

淀粉样β(Aβ)的可溶性寡聚物损害突触可塑性,扰乱神经元能量稳态,并与阿尔茨海默病(AD)的发病机制有关。因此,AD 药物研发的重要努力旨在防止 Aβ寡聚体的形成或阻断其神经毒性。真核延伸因子-2 激酶(eEF2K)在突触可塑性中发挥关键作用,并将神经传递与局部树突 mRNA 翻译偶联。最近的证据表明,Aβ寡聚体激活神经元 eEF2K,提示与 Aβ 诱导的突触功能障碍有关。然而,eEF2K 在 AD 发病机制中的作用以及 eEF2K 抑制在 AD 中的治疗潜力仍有待确定。在这里,我们表明 eEF2K 活性在 AD 患者死后大脑皮层和海马体中增加,并且在老年转基因 AD 小鼠的海马体中增加。此外,使用药理学或遗传学方法抑制 eEF2K 可防止 Aβ42 寡聚体对体外神经元活力和树突形成的毒性作用。我们还报告说,eEF2K 抑制可促进神经元细胞中核因子红细胞 2 相关因子(NRF2)的抗氧化反应,这对于在暴露于 Aβ42 寡聚体的神经元中 eEF2K 抑制的有益作用至关重要。因此,NRF2 敲低或 NRF2 抑制剂 Kelch-Like ECH-Associated Protein-1(Keap1)的过表达显著减弱了与 eEF2K 抑制相关的神经保护作用。最后,eEF2K 同源物 efk-1 的基因缺失减少了氧化应激,并改善了神经元中表达人 Aβ42 的 C. elegans 的趋化性和血清素敏感性。总之,这些发现强调了抑制 eEF2K 以减少 AD 中 Aβ 介导的氧化应激的潜力。

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