Department of Clinical Laboratory, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China.
Department of Gastroenterology, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China.
J Biol Chem. 2020 Oct 9;295(41):14125-14139. doi: 10.1074/jbc.RA119.010946. Epub 2020 Jun 29.
Autophagy has been shown to maintain neural system homeostasis during stroke. However, the molecular mechanisms underlying neuronal autophagy in ischemic stroke remain poorly understood. This study aims to investigate the regulatory mechanisms of the pathway consisting of MEG3 (maternally expressed gene 3), microRNA-378 (miR-378), and GRB2 (growth factor receptor-bound protein 2) in neuronal autophagy and neurological functional impairment in ischemic stroke. A mouse model of the middle cerebral artery occluded-induced ischemic stroke and an model of oxygen-glucose deprivation-induced neuronal injury were developed. To understand the role of the MEG3/miR-378/GRB2 axis in the neuronal regulation, the expression of proteins associated with autophagy in neurons was measured by Western blotting analysis, and neuron death was evaluated using a lactate dehydrogenase leakage rate test. First, it was found that the GRB2 gene, up-regulated in middle cerebral artery occluded-operated mice and oxygen-glucose deprivation-exposed neurons, was a target gene of miR-378. Next, miR-378 inhibited neuronal loss and neurological functional impairment in mice, as well as neuronal autophagy and neuronal death by silencing of GRB2. Confirmatory experiments showed that MEG3 could specifically bind to miR-378 and subsequently up-regulate the expression of GRB2, which in turn suppressed the activation of Akt/mTOR pathway. Taken together, these findings suggested that miR-378 might protect against neuronal autophagy and neurological functional impairment and proposed that a MEG3/miR-378/GRB2 regulatory axis contributed to better understanding of the pathophysiology of ischemic stroke.
自噬在中风期间被证明可以维持神经系统的内稳态。然而，缺血性中风中神经元自噬的分子机制仍知之甚少。本研究旨在探讨由 MEG3（母系表达基因 3）、miR-378（microRNA-378）和 GRB2（生长因子受体结合蛋白 2）组成的通路在神经元自噬和缺血性中风神经功能损伤中的调节机制。建立了大脑中动脉闭塞诱导的缺血性中风小鼠模型和氧葡萄糖剥夺诱导的神经元损伤模型。为了了解 MEG3/miR-378/GRB2 轴在神经元调节中的作用，通过 Western blot 分析测量了与自噬相关的蛋白质在神经元中的表达，并用乳酸脱氢酶漏出率试验评估了神经元死亡。首先，发现上调的 GRB2 基因在大脑中动脉闭塞操作的小鼠和氧葡萄糖剥夺暴露的神经元中是 miR-378 的靶基因。接下来，miR-378 通过沉默 GRB2 抑制了小鼠的神经元丢失和神经功能损伤，以及神经元自噬和神经元死亡。验证性实验表明，MEG3 可以特异性结合 miR-378，随后上调 GRB2 的表达，进而抑制 Akt/mTOR 通路的激活。总之，这些发现表明 miR-378 可能防止神经元自噬和神经功能损伤，并提出了 MEG3/miR-378/GRB2 调节轴有助于更好地理解缺血性中风的病理生理学。
