MicroRNA-146a inhibition promotes total neurite outgrowth and suppresses cell apoptosis, inflammation, and STAT1/MYC pathway in PC12 and cortical neuron cellular Alzheimer's disease models

This study aimed to explore the effect of microRNA (miR)-146a inhibition on regulating cell apoptosis, total neurite outgrowth, inflammation, and STAT1/MYC pathway in Alzheimer's disease (AD). PC12 and cortical neuron cellular AD models were constructed by Aβ1-42 insult. For the former model, nerve growth factor (NGF) stimulation was previously conducted. miR-146a inhibitor and negative-control (NC) inhibitor were transfected into the two cellular AD models, and then cells were named miR-inhibitor group and NC-inhibitor group, respectively. After transfection, cell apoptosis, total neurite outgrowth, supernatant inflammation cytokines, and STAT1/MYC pathway were detected. miR-146a expression was similar between PC12 cellular AD model and control cells (NGF-stimulated PC12 cells), while miR-146a expression was increased in cortical neuron cellular AD model compared with control cells (rat embryo primary cortical neurons). In both PC12 and cortical neuron cellular AD models, miR-146a expression was reduced in miR-inhibitor group compared with NC-inhibitor group after transfection. Furthermore, cell apoptosis was attenuated, while total neurite outgrowth was elevated in miR-inhibitor group compared with NC-inhibitor group. As for supernatant inflammatory cytokines, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and IL-17 levels were lower in miR-inhibitor group than in NC-inhibitor group. Additionally, STAT1 and c-Myc mRNA and protein expressions were attenuated in miR-inhibitor group compared with NC-inhibitor group. In conclusion, miR-146a potentially represented a viable therapeutic target for AD.

本研究旨在探究微小RNA（microRNA, miR）-146a抑制对阿尔茨海默病（Alzheimer's disease, AD）中细胞凋亡、总神经突生长、炎症反应及STAT1/MYC通路的调控效应。本研究通过Aβ1-42损伤构建PC12细胞与皮层神经元阿尔茨海默病细胞模型，其中PC12细胞模型此前已完成神经生长因子（nerve growth factor, NGF）刺激预处理。将miR-146a抑制剂与阴性对照（negative-control, NC）抑制剂分别转染至两类阿尔茨海默病细胞模型，对应细胞分别命名为miR抑制剂组与NC抑制剂组。转染完成后，检测各组细胞的凋亡水平、总神经突生长情况、上清液炎症细胞因子含量及STAT1/MYC通路相关指标。结果显示，PC12阿尔茨海默病细胞模型与对照细胞（经NGF刺激的PC12细胞）中miR-146a的表达水平无显著差异；而皮层神经元阿尔茨海默病细胞模型中miR-146a的表达水平较对照细胞（大鼠胚胎原代皮层神经元）显著升高。在两类阿尔茨海默病细胞模型中，转染后miR抑制剂组的miR-146a表达水平均显著低于NC抑制剂组。进一步实验发现，相较于NC抑制剂组，miR抑制剂组的细胞凋亡程度显著减弱，总神经突生长水平明显提升。在上清液炎症细胞因子方面，miR抑制剂组的肿瘤坏死因子-α、白细胞介素（interleukin, IL）-1β、IL-6及IL-17水平均低于NC抑制剂组。此外，相较于NC抑制剂组，miR抑制剂组中STAT1与c-Myc的mRNA及蛋白表达水平均显著下调。综上，miR-146a有望成为阿尔茨海默病极具临床转化价值的治疗靶点。