Table_11_miR-30 Family miRNAs Mediate the Effect of Chronic Social Defeat Stress on Hippocampal Neurogenesis in Mouse Depression Model.pdf

Depression is a debilitating psychiatric disorder with a high rate of relapse and a low rate of response to antidepressant treatment. There is a dearth of new antidepressants due to an incomplete understanding of the molecular mechanisms involved in its etiopathology. Chronic stress appears to be one of the foremost underlying causes of depression. Studies in animal models in the past decade have implicated epigenetic mechanisms in mediating the negative effects of chronic stressful events on the progression/manifestation of depression and other co-morbid neuropsychiatric disorders. However, non-coding RNAs, another layer of epigenetic regulation is relatively less studied in depression. Here, using the chronic social defeat stress (CSDS)-induced depression model, we hypothesized dysregulation in miRNA-mRNA networks in the neurogenic dentate gyrus (DG) region of male C57BL/6 mice. Among several dysregulated miRNAs identified via miRNA arrays, the most striking finding was the downregulation of miRNAs of the miR-30 family in stressed/defeated mice. To investigate miRNAs in the DG-resident neural stem/progenitor cells (NSCs/NPCs), we used the in vitro neurosphere culture, where proliferating NSCs/NPCs were subjected to differentiation. Among several differentially expressed miRNAs, we observed an upregulation of miR-30 family miRNAs upon differentiation. To search for the gene targets of these miRNAs, we performed gene arrays followed by bioinformatics analysis, miRNA manipulations and luciferase assays. Our results suggest that miR-30 family miRNAs mediate chronic stress-induced depression-like phenotype by altering hippocampal neurogenesis and neuroplasticity via controlling the epigenetic and transcription regulators such as Mll3 and Runx1; and cell signaling regulators like Socs3, Ppp3r1, Gpr125, and Nrp1.

抑郁症是一种致残性精神疾病，兼具高复发率与低抗抑郁治疗应答率。由于对其发病机制的分子通路尚缺乏完整认识，新型抗抑郁药物研发匮乏。慢性应激被认为是抑郁症最主要的潜在致病因素之一。过去十年间的动物模型研究证实，表观遗传机制（epigenetic mechanisms）可介导慢性应激事件对抑郁症及其他共病神经精神疾病的进展与临床表现产生负面影响。然而，作为另一类表观遗传调控机制的非编码RNA（non-coding RNAs），在抑郁症领域的相关研究仍相对不足。本研究采用慢性社交挫败应激（chronic social defeat stress, CSDS）诱导的抑郁模型，推测雄性C57BL/6小鼠具备神经发生能力的齿状回（dentate gyrus, DG）区域内存在微小RNA（microRNA, miRNA）-信使RNA（messenger RNA, mRNA）网络失调。借助miRNA芯片筛选出多个差异表达miRNA后，本研究最核心的发现为：应激/挫败小鼠体内miR-30家族miRNA的表达出现下调。为探究齿状回驻留神经干/祖细胞（neural stem/progenitor cells, NSCs/NPCs）中的miRNA功能，本研究建立了体外神经球培养体系，对增殖状态的神经干/祖细胞实施分化诱导。在多个差异表达的miRNA中，我们观察到分化过程中miR-30家族miRNA的表达显著上调。为筛选上述miRNA的靶标基因，本研究实施了基因芯片检测，后续开展了生物信息学分析、miRNA干预实验与荧光素酶报告基因实验（luciferase assays）。本研究结果显示，miR-30家族miRNA可通过调控表观遗传与转录调控因子（如Mll3、Runx1）以及细胞信号调控因子（如Socs3、Ppp3r1、Gpr125和Nrp1），改变海马神经发生与神经可塑性，进而介导慢性应激诱导的抑郁样表型。