Decline of protein quality control in neurons contributes to age-related neurodegenerative disorders caused by misfolded proteins. 4E-BP1 is a key node in the regulation of protein synthesis, as activated 4E-BP1 represses global protein translation. Overexpression of 4E-BP1 mediates the benefits of dietary restriction and can counter metabolic stress, and 4E-BP1 disinhibition on mTORC1 repression may be neuroprotective; however, whether 4E-BP1 overexpression is neuroprotective in mammalian neurons is yet to be fully explored. To address this question, we generated 4E-BP1-overexpressing transgenic mice and confirmed marked reductions in protein translation in 4E-BP1-overexpressing primary neurons. After documenting that 4E-BP1-overexpressing neurons are resistant to proteotoxic stress elicited by brefeldin A treatment, we exposed primary neurons to three different Parkinson's disease (PD)-linked toxins (rotenone, maneb, or paraquat) and documented significant protection in neurons from newborn male and female 4E-BP1-OE transgenic mice. We observed 4E-BP1-dependent upregulation of genes encoding proteins that comprise the mitochondrial unfolded protein response, and noted 4E-BP1 overexpression required activation of the mitochondrial unfolded protein response for neuroprotection against rotenone toxicity. We also tested whether 4E-BP1 could prevent α-synuclein neurotoxicity by treating 4E-BP1-overexpressing primary neurons with α-synuclein preformed fibrils, and we observed marked reductions in α-synuclein aggregation and neurotoxicity, thus validating that 4E-BP1 is a powerful suppressor of PD-linked pathogenic insults. Our results indicate that increasing 4E-BP1 expression or enhancing 4E-BP1 activation can robustly induce the mitochondrial unfolded protein response and thus could be an appealing strategy for treating a variety of neurodegenerative diseases, including especially PD.

SIGNIFICANCE STATEMENT In neurodegenerative disease, misfolded proteins accumulate and overwhelm normal systems of homeostasis and quality control. One mechanism for improving protein quality control is to reduce protein translation. Here we investigated whether neuronal overexpression of 4E-BP1, a key repressor of protein translation, can protect against misfolded protein stress and toxicities linked to Parkinson's disease, and found that 4E-BP1 overexpression prevented cell death in neurons treated with brefeldin A, rotenone, maneb, paraquat, or preformed fibrils of α-synuclein. When we sought the basis for 4E-BP1 neuroprotection, we discovered that 4E-BP1 activation promoted the mitochondrial unfolded protein response. Our findings highlight 4E-BP1 as a therapeutic target in neurodegenerative disease and underscore the importance of the mitochondrial unfolded protein response in neuroprotection against various insults.

神经元中蛋白质质量控​​制的下降导致了由错误折叠的蛋白质引起的与年龄相关的神经退行性疾病。4E-BP1是蛋白质合成调控中的关键节点，因为活化的4E-BP1抑制整体蛋白质翻译。4E-BP1的过表达介导饮食限制的益处，并可以抵抗代谢压力，而4E-BP1对mTORC1抑制的抑制作用可能具有神经保护作用。然而，在哺乳动物神经元中4E-BP1过表达是否具有神经保护作用尚待充分探讨。为了解决这个问题，我们产生了过表达4E-BP1的转基因小鼠，并证实过表达4E-BP1的原代神经元蛋白质翻译显着减少。在证明过表达4E-BP1的神经元对布雷菲德菌素A处理引起的蛋白毒性应激具有抗性后，4E-BP1-OE转基因小鼠。我们观察到了编码包含线粒体未折叠蛋白应答的蛋白质的基因的4E-BP1依赖性上调，并注意到4E-BP1过表达需要激活线粒体未折叠蛋白应答才能对鱼藤酮毒性进行神经保护。我们还测试了4E-BP1是否可以通过用α-突触核蛋白预制的原纤维处理过表达4E-BP1的原代神经元来预防α-突触核蛋白的神经毒性，并且我们观察到α-突触核蛋白的聚集和神经毒性显着降低，因此证实4E-BP1是一种PD致病性损伤的强大抑制因子。我们的结果表明，增加4E-BP1表达或增强4E-BP1激活可以强有力地诱导线粒体展开的蛋白质反应，因此可能是治疗多种神经退行性疾病的诱人策略，

重要性声明在神经退行性疾病中，错误折叠的蛋白质会积累并压倒正常的体内平衡和质量控制系统。改善蛋白质质量控​​制的一种机制是减少蛋白质翻译。在这里，我们研究了神经元过表达4E-BP1（蛋白翻译的关键阻遏物）是否可以防止错误折叠的蛋白应激反应和与帕金森氏病相关的毒性，并发现4E-BP1过表达可以防止用布雷菲德菌素A，鱼藤酮， maneb，百草枯或预制的α-突触核蛋白原纤维。当我们寻求4E-BP1神经保护的基础时，我们发现4E-BP1激活促进了线粒体展开的蛋白反应。