Fine tuning of the unfolded protein response by ISRIB improves neuronal survival in a model of amyotrophic lateral sclerosis
Fine tuning of the unfolded protein response by ISRIB improves neuronal survival in a model of amyotrophic lateral sclerosis
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DOI：
10.1038/s41419-020-2601-2
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发表时间：
2020-05-26
影响因子：
9
通讯作者：
Aragon, Tomas
中科院分区：
文献类型：
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作者：
Bugallo, Ricardo;Marlin, Elias;Aragon, Tomas
蛋白质折叠稳态的丧失是许多最普遍的神经退行性疾病的特征。作为内质网（ER）折叠应激的应对机制，未折叠蛋白反应（UPR）包括一组信号机制，启动基因表达程序以恢复蛋白质平衡，或者当应激是慢性或压倒性时促进神经元死亡。普遍定期审议的这种决定命运的能力被认为在肌萎缩性侧索硬化症（ALS）中发挥关键作用。然而，探索UPR调节的治疗潜力的一些遗传学或药理学尝试产生了相互矛盾的观察结果。为了建立UPR信号与ALS患者神经元死亡之间的确切关系，我们开发了一个神经元模型，在该模型中，通过自动显微镜可以纵向监测单个神经元在神经退行性变过程中的家族性ALS致病等位基因（突变体G93A SOD1）的毒性和UPR激活。使用荧光UPR报告器，我们通过Cox回归模型建立了UPR与神经元死亡之间的时间和因果关系。对离散UPR过程的药物抑制使我们能够确定PERK （pkr样ER激酶）和IRE1（肌醇要求酶-1）机制对神经元命运的贡献。重要的是，通过其下游抑制剂ISRIB抑制PERK信号，而不是直接的PERK激酶抑制剂GSK2606414，显著提高了表达sod1的G93A神经元的存活。两种药物在内质网应激下的抑制特性表征表明，在神经元中（而不是在胶质细胞中），ISRIB仅推翻了PERK施加的部分翻译程序，减轻了对翻译的一般抑制，但保持了ATF4（激活转录因子4）信使RNA的特权翻译。令人惊讶的是，在表达sod1的G93A神经元中，PERK输出的微调导致ire1依赖性信号的减少。总之，我们的研究结果确定了isrib介导的翻译重编程是一种新的潜在的ALS治疗方法。
Loss of protein folding homeostasis features many of the most prevalent neurodegenerative disorders. As coping mechanism to folding stress within the endoplasmic reticulum (ER), the unfolded protein response (UPR) comprises a set of signaling mechanisms that initiate a gene expression program to restore proteostasis, or when stress is chronic or overwhelming promote neuronal death. This fate-defining capacity of the UPR has been proposed to play a key role in amyotrophic lateral sclerosis (ALS). However, the several genetic or pharmacological attempts to explore the therapeutic potential of UPR modulation have produced conflicting observations. In order to establish the precise relationship between UPR signaling and neuronal death in ALS, we have developed a neuronal model where the toxicity of a familial ALS-causing allele (mutant G93A SOD1) and UPR activation can be longitudinally monitored in single neurons over the process of neurodegeneration by automated microscopy. Using fluorescent UPR reporters we established the temporal and causal relationship between UPR and neuronal death by Cox regression models. Pharmacological inhibition of discrete UPR processes allowed us to establish the contribution of PERK (PKR-like ER kinase) and IRE1 (inositol-requiring enzyme-1) mechanisms to neuronal fate. Importantly, inhibition of PERK signaling with its downstream inhibitor ISRIB, but not with the direct PERK kinase inhibitor GSK2606414, significantly enhanced the survival of G93A SOD1-expressing neurons. Characterization of the inhibitory properties of both drugs under ER stress revealed that in neurons (but not in glial cells) ISRIB overruled only part of the translational program imposed by PERK, relieving the general inhibition of translation, but maintaining the privileged translation of ATF4 (activating transcription factor 4) messenger RNA. Surprisingly, the fine-tuning of the PERK output in G93A SOD1-expressing neurons led to a reduction of IRE1-dependent signaling. Together, our findings identify ISRIB-mediated translational reprogramming as a new potential ALS therapy.