Increasing glutathione levels by a novel posttranslational mechanism inhibits neuronal hyperexcitability.
Increasing glutathione levels by a novel posttranslational mechanism inhibits neuronal hyperexcitability.
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通过一种新的翻译后机制提高谷胱甘肽水平可抑制神经元的过度兴奋。
DOI：
10.1016/j.redox.2023.102895
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发表时间：
2023-11
期刊：
影响因子：
11.4
通讯作者：
Patel M
中科院分区：
文献类型：
--
作者：
Sri Hari A;Banerji R;Liang LP;Fulton RE;Huynh CQ;Fabisiak T;McElroy PB;Roede JR;Patel M
在实验动物模型和癫痫患者中观察到谷胱甘肽(GSH)耗竭和氧化还原动态平衡受损。通过转录调控提高GSH水平的多效性策略已被证明可以显著降低氧化应激和癫痫发作频率，提高癫痫发作阈值，并挽救某些认知缺陷。GSH升高本身是否会改变神经元的超兴奋性，目前还没有答案。我们先前的研究表明，硫醇如二硫代己醇(DMP)通过谷氨酸半胱氨酸连接酶(GCL)的翻译后激活来升高GSH，GCL是GSH生物合成的限速酶。在这里，我们问的是，在体外和体内，DMP升高细胞内GSH是否改变了神经元的超兴奋性。用DMP处理原代培养的神经元-神经胶质细胞可升高GSH，并抑制电压门控性钾通道阻滞剂(4-氨基吡啶，4AP)诱导的神经元超兴奋性。DMP可增加野生型(WT)斑马鱼幼体中的GSH，并显著减弱惊厥戊四氮(PTZ)诱导的急性“癫痫样”游泳行为。DMP治疗增加了谷胱甘肽，并抑制了Dravet综合征(DS)斑马鱼幼体(Scn1Lab)的抽搐、自发的“癫痫样”游泳行为。此外，DMP处理显著减少了scn1Lab斑马鱼幼体的自发电惊厥和相关的惊厥参数。我们研究了氧化还原敏感的哺乳动物雷帕霉素靶标(MTOR)通路的作用，这是由于存在几种富含半胱氨酸的蛋白，以及它们参与调节神经元的兴奋性。用4AP或谷胱甘肽生物合成的不可逆阻断剂L-丁硫氨酸-(S，R)-亚磺胺处理原代培养的神经元-神经胶质细胞，可显著增加mTOR复合体I(MTORC_1)的活性。此外，BSO介导的GSH耗竭氧化修饰了结节性硬化症蛋白复合体(TSC)，该复合体由Hamartin(TSC1)、tuberin(TSC2)和Tbc1结构域家族成员7(TBC1D7)组成，这些都是mTORC1的关键负调控因子。综上所述，我们的结果表明，通过一种新的翻译后机制，DMP介导的GSH升高在体外和体内都可以抑制神经元的超兴奋性，一个可能的联系是氧化还原敏感的mTORC1通路。一种能够提高谷胱甘肽水平的化合物，可以抑制神经元的超兴奋性。一种能够提高谷胱甘肽水平的化合物，可减轻斑马鱼幼体的癫痫发作。谷胱甘肽的变化影响雷帕霉素复合体I途径的哺乳动物靶点。
Glutathione (GSH) depletion, and impaired redox homeostasis have been observed in experimental animal models and patients with epilepsy. Pleiotropic strategies that elevate GSH levels via transcriptional regulation have been shown to significantly decrease oxidative stress and seizure frequency, increase seizure threshold, and rescue certain cognitive deficits. Whether elevation of GSH per se alters neuronal hyperexcitability remains unanswered. We previously showed that thiols such as dimercaprol (DMP) elevate GSH via post-translational activation of glutamate cysteine ligase (GCL), the rate limiting GSH biosynthetic enzyme. Here, we asked if elevation of cellular GSH by DMP altered neuronal hyperexcitability in-vitro and in-vivo. Treatment of primary neuronal-glial cerebrocortical cultures with DMP elevated GSH and inhibited a voltage-gated potassium channel blocker (4-aminopyridine, 4AP) induced neuronal hyperexcitability. DMP increased GSH in wildtype (WT) zebrafish larvae and significantly attenuated convulsant pentylenetetrazol (PTZ)-induced acute ‘seizure-like’ swim behavior. DMP treatment increased GSH and inhibited convulsive, spontaneous ‘seizure-like’ swim behavior in the Dravet Syndrome (DS) zebrafish larvae (scn1Lab). Furthermore, DMP treatment significantly decreased spontaneous electrographic seizures and associated seizure parameters in scn1Lab zebrafish larvae. We investigated the role of the redox-sensitive mammalian target of rapamycin (mTOR) pathway due to the presence of several cysteine-rich proteins and their involvement in regulating neuronal excitability. Treatment of primary neuronal-glial cerebrocortical cultures with 4AP or l-buthionine-(S,R)-sulfoximine (BSO), an irreversible inhibitor of GSH biosynthesis, significantly increased mTOR complex I (mTORC1) activity which was rescued by pre-treatment with DMP. Furthermore, BSO-mediated GSH depletion oxidatively modified the tuberous sclerosis protein complex (TSC) consisting of hamartin (TSC1), tuberin (TSC2), and TBC1 domain family member 7 (TBC1D7) which are critical negative regulators of mTORC1. In summary, our results suggest that DMP-mediated GSH elevation by a novel post-translational mechanism can inhibit neuronal hyperexcitability both in-vitro and in-vivo and a plausible link is the redox sensitive mTORC1 pathway. A compound capable of elevating glutathione levels, inhibits neuronal hyperexcitability. A compound capable of elevating glutathione levels, attenuates seizures in zebrafish larvae. Changes in glutathione impact the mammalian target of rapamycin complex I pathway.
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