Department of Orthopedics, West China Hospital, Sichuan University, Chengdu, 610041, Sichuan, China.
Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, 610041, Sichuan, China; Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, Sichuan University, Chengdu, 610041, Sichuan, China.
Neurosci Lett. 2020 May 14;727:134937. doi: 10.1016/j.neulet.2020.134937. Epub 2020 Mar 31.
Spinal cord injury (SCI) is one of the most serious neurological disorders and is characterized by high morbidity and disability. Unfortunately, there is a lack of effective treatment. Recently, the micro RNA, miR-384-5p, was reported to play a significant role in cell survival in response to different insults.
In vitro model of traumatic neuronal injury was induced by application of a sharp sterile blade to generate cuts in PC12 cells, and in vivo SCI was produced by applying vascular clips (force of 15 g) to the dura via T9-T10 laminectomy, and then, the role of miR-384-5p in the development of SCI was investigated.
Dual-luciferase reporter assays confirmed that miR-384-5p regulates the gene expression of Beclin-1, an important promoter of autophagy. Quantitative polymerase chain reaction and western blot analyses revealed that treatment with miR-384-5p decreased mRNA and protein expression of Beclin-1 in the mechanically injured PC12 cells. In rats with spinal cord compression injuries, miR-384-5p expression was significantly decreased. Treatment with miR-384-5p increased spinal cord neuron survival and promoted locomotor function recovery in rats. Further study revealed that miR-384-5p administration decreased immunofluorescent labeling of Beclin-1 in spinal cord tissues and reduced autophagosome formation in neurons, as shown by transmission electron microscopy. These results indicated that miR-384-5p promotes recovery of rats with SCI by suppressing autophagy via direct targeting of Beclin-1. Moreover, miR-384-5p also inhibited the activation of endoplasmic reticulum (ER) stress by decreasing GRP78 expression in both in vitro and in vivo models.
This study for the first time demonstrates that the protective role of miR-384-5p in the process of SCI is associated with simultaneous suppression of autophagy and ER stress and miR-384-5p could be a promising candidate for SCI therapeutics.
脊髓损伤 (SCI) 是最严重的神经障碍之一，其特点是发病率和残疾率高。不幸的是，目前缺乏有效的治疗方法。最近，研究表明 microRNA，miR-384-5p 在应对不同损伤时对细胞存活起着重要作用。
通过应用无菌锋利刀片在 PC12 细胞上产生切割来诱导体外创伤性神经元损伤模型，通过 T9-T10 椎板切除术在硬脑膜上施加血管夹（15g 力）来产生体内 SCI，并研究 miR-384-5p 在 SCI 发展中的作用。
双荧光素酶报告实验证实 miR-384-5p 调节自噬的重要启动子 Beclin-1 的基因表达。定量聚合酶链反应和 Western blot 分析显示，miR-384-5p 处理可降低机械损伤的 PC12 细胞中 Beclin-1 的 mRNA 和蛋白表达。在脊髓压迫损伤大鼠中，miR-384-5p 的表达明显降低。miR-384-5p 治疗可增加脊髓神经元的存活并促进大鼠运动功能的恢复。进一步研究表明，miR-384-5p 给药可减少脊髓组织中 Beclin-1 的免疫荧光标记，并通过透射电子显微镜减少神经元中自噬体的形成。这些结果表明，miR-384-5p 通过直接靶向 Beclin-1 抑制自噬来促进 SCI 大鼠的恢复。此外，miR-384-5p 还通过降低内质网 (ER) 应激中 GRP78 的表达来抑制 ER 应激的激活，无论是在体外还是体内模型中。
本研究首次证明，miR-384-5p 在 SCI 过程中的保护作用与同时抑制自噬和 ER 应激有关，miR-384-5p 可能是 SCI 治疗的有前途的候选药物。
