Department of Pharmacology, Teikyo University School of Medicine, Tokyo, Japan.
Laboratory of Drug and Gene Delivery, Faculty of Pharma-Science, Teikyo University, Tokyo, Japan.
Commun Biol. 2021 Feb 10;4(1):182. doi: 10.1038/s42003-021-01706-0.
Glutathione (GSH) is an important antioxidant that plays a critical role in neuroprotection. GSH depletion in neurons induces oxidative stress and thereby promotes neuronal damage, which in turn is regarded as a hallmark of the early stage of neurodegenerative diseases. The neuronal GSH level is mainly regulated by cysteine transporter EAAC1 and its inhibitor, GTRAP3-18. In this study, we found that the GTRAP3-18 level was increased by up-regulation of the microRNA miR-96-5p, which was found to decrease EAAC1 levels in our previous study. Since the 3'-UTR region of GTRAP3-18 lacks the consensus sequence for miR-96-5p, an unidentified protein should be responsible for the intermediate regulation of GTRAP3-18 expression by miR-96-5p. Here, we discovered that RNA-binding protein NOVA1 functions as an intermediate protein for GTRAP3-18 expression via miR-96-5p. Moreover, we show that intra-arterial injection of a miR-96-5p-inhibiting nucleic acid to living mice by a drug delivery system using microbubbles and ultrasound decreased the level of GTRAP3-18 via NOVA1 and increased the levels of EAAC1 and GSH in the dentate gyrus of the hippocampus. These findings suggest that the delivery of a miR-96-5p inhibitor to the brain would efficiently increase the neuroprotective activity by increasing GSH levels via EAAC1, GTRAP3-18 and NOVA1.
谷胱甘肽 (GSH) 是一种重要的抗氧化剂，在神经保护中起着关键作用。神经元中 GSH 的消耗会诱导氧化应激，从而促进神经元损伤，这反过来又被认为是神经退行性疾病早期阶段的标志。神经元中的 GSH 水平主要由半胱氨酸转运体 EAAC1 及其抑制剂 GTRAP3-18 调节。在这项研究中，我们发现 miR-96-5p 的上调会增加 GTRAP3-18 的水平，而我们之前的研究发现 miR-96-5p 会降低 EAAC1 的水平。由于 GTRAP3-18 的 3'-UTR 区域缺乏 miR-96-5p 的共识序列，因此应该有一种未知的蛋白质负责 miR-96-5p 对 GTRAP3-18 表达的中间调节。在这里，我们发现 RNA 结合蛋白 NOVA1 作为 miR-96-5p 表达的中间蛋白起作用。此外，我们还表明，通过使用微泡和超声的药物输送系统将 miR-96-5p 抑制性核酸递送到活小鼠的动脉内，可以通过 NOVA1 降低 GTRAP3-18 的水平，并增加海马齿状回中 EAAC1 和 GSH 的水平。这些发现表明，向大脑递送 miR-96-5p 抑制剂可以通过增加 EAAC1、GTRAP3-18 和 NOVA1 来有效增加 GSH 水平，从而提高神经保护活性。
