Sun Liqian, Zhao Manman, Wang Yan, Liu Aihua, Lv Ming, Li Youxiang, Yang Xinjian, Wu Zhongxue
Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, China.
Department of Histology and Embryology, School of Basic Medical Science, North China University of Science and Technology, Hebei, Tangshan 063000, China.
Biochem Biophys Res Commun. 2017 Jan 22;482(4):1141-1147. doi: 10.1016/j.bbrc.2016.12.001. Epub 2016 Dec 2.
MicroRNA-27a (miR-27a) has been reported to be a brain-specific miRNA and aberrantly expressed in the brain suffered from traumatic brain injury (TBI). The present study is designed to investigate the potential role and molecular mechanism of miR-27a in the pathogenesis of TBI. The level of miR-27a in brain was manipulated by intracerebroventricular injection of lentiviral-encoding miR-27a before TBI induction. Real-time PCR was used to detected miR-27a and Forkhead box O3a (FoxO3a) levels in the hippocampus. Then, we evaluated the impact of miR-27a overexpression on neurological function, brain edema, lesion volume and neuronal autophagy after TBI. The blinding of miR-27a to the 3'UTR of FoxO3a mRNA and its effects on FoxO3a translation were analyzed by luciferase reporter assay and Western blot. The downregulation of miR-27a and the increase in FoxO3a level were observed in the hippocampus post-TBI. Overexpression of miR-27a significantly attenuated neurological deficits and brain injury, especially suppressed autophagic activation after TBI. Furthermore, we identified that miR-27a directly targeted the FoxO3a 3'UTR region to reduced FoxO3a protein expression. Knockdown of FoxO3a significantly reversed high levels of autophagy-related genes induced by TBI. Taken together, Overexpression of miR-27a may protect against brain injury via suppressing FoxO3a-mediated neuronal autophagy following TBI.
据报道，微小RNA-27a（miR-27a）是一种脑特异性微小RNA，在创伤性脑损伤（TBI）的大脑中异常表达。本研究旨在探讨miR-27a在TBI发病机制中的潜在作用和分子机制。在诱导TBI之前，通过脑室内注射编码miR-27a的慢病毒来调控大脑中miR-27a的水平。采用实时定量PCR检测海马中miR-27a和叉头框O3a（FoxO3a）的水平。然后，我们评估了miR-27a过表达对TBI后神经功能、脑水肿、损伤体积和神经元自噬的影响。通过荧光素酶报告基因检测和蛋白质免疫印迹分析miR-27a与FoxO3a mRNA的3'非翻译区（3'UTR）的结合及其对FoxO3a翻译的影响。TBI后海马中观察到miR-27a下调和FoxO3a水平升高。miR-27a过表达显著减轻神经功能缺损和脑损伤，尤其是抑制TBI后的自噬激活。此外，我们发现miR-27a直接靶向FoxO3a的3'UTR区域以降低FoxO3a蛋白表达。敲低FoxO3a可显著逆转TBI诱导的高水平自噬相关基因。综上所述，miR-27a过表达可能通过抑制TBI后FoxO3a介导的神经元自噬来保护大脑免受损伤。
