MicroRNA Mapping in Major Depression

描述（由申请人提供）：重度抑郁症是影响全世界数百万人的最严重和使人衰弱的疾病之一。尽管在过去的几十年里取得了相当大的进步，但对重度抑郁症的病因仍缺乏明确的认识。越来越多的证据表明，重度抑郁症可能是由细胞级联损伤引起的，细胞级联损伤导致调节情绪、认知和神经植物功能的回路中的信息处理异常。最近，microRNAs （miRNAs）作为一类重要的非编码小rna，通过与mRNA的3' UTR结合，抑制特定mRNA靶点的翻译和/或稳定性。由于mirna表现出高度调控的表达，它们有助于特定转录组的发育和维持，因此具有影响生理和疾病表型的独特能力。我们最近的研究表明，一组mirna的表达在MDD受试者的PFC中发生了改变，并且它们与应对应激反应有关。此外，越来越多的证据表明mirna参与神经可塑性。这些研究表明，mirna很有可能在MDD的发病机制中发挥重要作用。我们假设，在协调的方式下，mirna的亚群及其变体将在MDD大脑中表现出差异共表达，通过影响特定的神经/突触mRNA靶点和细胞通路，参与MDD的发病机制。在从MDD和对照组中获得的具有良好特征的死后脑样本中，我们建议：1)通过小RNA测序分析miRNA表达，鉴定新的miRNA，并分析差异表达的miRNA；2)通过RNA测序分析mRNA表达，通过绘制共表达网络模块，确定mRNA与miRNA之间的调控关系；3)分析miRNA-mRNA对，实验验证改变的mirna和特定靶基因，并在细胞水平上定位这些变化；4)分析MDD中差异共表达模块的相关通路；5)通过测定pri-/pre-miRNA、RISC复合物和生物发生机制的组成部分来检测miRNA的生物发生；6)通过小RNA测序检测突触小体中miRNA的富集程度，分析miRNA- mrna在突触部分特异性改变的靶基因和共表达模块，以及在突触水平检测pri-/pre-miRNA和miRNA生物发生机制的组成部分，研究突触miRNA在MDD发病机制中的作用。通过结合最先进的高通量小RNA和RNA测序，通过新型生物信息学工具和验证分析数据，确定特定细胞类型中mirna及其靶点的变化，并检查mirna在突触水平上在涉及情绪和认知的大脑区域中的作用，我们提出的研究在分子水平上推进MDD研究领域具有独特的定位。这些研究将为mirna作为“分子工具”的发展提供新的途径，有可能产生新的基于分子的疗法来治疗这种毁灭性的疾病。

DESCRIPTION (provided by applicant): MDD is one of the most severe and debilitating illnesses that affects millions of individuals worldwide. Despite considerable advances over the past decades, a clear understanding of the etiology of MDD is still lacking. Accumulating evidence suggests that MDD may arise from impairments in cellular cascades, which lead to aberrant information processing in the circuits that regulate mood, cognition, and neurovegetative functions. Recently, microRNAs (miRNAs) have emerged as an important class of small non-coding RNAs that by binding to 3' UTR of mRNAs, suppress the translation and/or stability of specific mRNA targets. Since miRNAs show a highly regulated expression, they contribute in the development and maintenance of a specific transcriptome and thus have the unique ability to influence physiological and disease phenotypes. Our recent studies show that the expression of a group of miRNAs is altered in PFC of MDD subjects and that they are involved in coping response to stress. In addition, accumulative evidence points to the involvement of miRNAs in neural plasticity. These studies suggest a strong possibility that miRNAs may contribute significantly to the etiopathogenesis of MDD. We hypothesize that subsets of miRNAs and their variants, regulated in a coordinated fashion, will show differential co-expression in MDD brain, which by affecting specific neural/synaptic mRNA targets and cellular pathways, will participate in MDD pathogenesis. In well characterized postmortem brain samples obtained from MDD and control subjects, we propose to: 1) profile miRNA expression by small RNA sequencing, identify novel miRNAs, and analyze differentially expressed miRNAs; 2) profile mRNA expression by RNA sequencing and identify regulatory relationships between mRNA and miRNA by mapping co-expression network modules; 3) analyze miRNA-mRNA pairs, validate altered miRNAs and specific target genes experimentally, and localize these changes at the cellular level; 4) analyze pathway associated with differentially co-expressed modules in MDD; 5) examine miRNA biogenesis by determining pri-/pre-miRNAs, RISC complexes, and components of biogenesis machinery; and 6) examine the role of synaptic miRNAs in MDD pathogenesis by determining miRNA enrichment via small RNA sequencing in synaptosomes, analyzing target genes and co-expression modules of miRNA-mRNA specifically altered in the synaptic fraction, and examining pri-/pre-miRNAs and components of miRNA biogenesis machinery at synaptic level. By using a combination of the state-of-the-art high throughput small RNA and RNA sequencing, analyzing data by novel bioinformatics tools and validation, identifying changes in miRNAs and their targets in specific cell type(s), and examining the role of miRNAs at the synaptic level in brain regions implicated in mood and cognition, our proposed study is uniquely positioned to advance the field of MDD research at the molecular level. These investigations will provide novel avenues for the development of miRNAs as ''molecular tools'' with the potential to generate new molecular-based therapies to treat this devastating disorder.