Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada.
McGill Group for Suicide Studies, Douglas Mental Health University Institute, Verdun, Quebec, Canada.
Int J Neuropsychopharmacol. 2024 Mar 1;27(3). doi: 10.1093/ijnp/pyae013.
Major depressive disorder (MDD) is a leading cause of disability with significant mortality risk. Despite progress in our understanding of the etiology of MDD, the underlying molecular changes in the brain remain poorly understood. Extracellular vesicles (EVs) are lipid-bound particles that can reflect the molecular signatures of the tissue of origin. We aimed to optimize a streamlined EV isolation protocol from postmortem brain tissue and determine whether EV RNA cargo, particularly microRNAs (miRNAs), have an MDD-specific profile.
EVs were isolated from postmortem human brain tissue. Quality was assessed using western blots, transmission electron microscopy, and microfluidic resistive pulse sensing. EV RNA was extracted and sequenced on Illumina platforms. Functional follow-up was performed in silico.
Quality assessment showed an enrichment of EV markers, as well as a size distribution of 30 to 200 nm in diameter, and no contamination with cellular debris. Small RNA profiling indicated the presence of several RNA biotypes, with miRNAs and transfer RNAs being the most prominent. Exploring miRNA levels between groups revealed decreased expression of miR-92a-3p and miR-129-5p, which was validated by qPCR and was specific to EVs and not seen in bulk tissue. Finally, in silico functional analyses indicate potential roles for these 2 miRNAs in neurotransmission and synaptic plasticity.
We provide a streamlined isolation protocol that yields EVs of high quality that are suitable for molecular follow-up. Our findings warrant future investigations into brain EV miRNA dysregulation in MDD.
重度抑郁症（MDD）是导致残疾的主要原因，具有显著的死亡风险。尽管我们对 MDD 的病因有了更多的了解，但大脑中潜在的分子变化仍知之甚少。细胞外囊泡（EVs）是带有脂质的颗粒，可以反映起源组织的分子特征。我们旨在优化从死后脑组织中提取 EV 的简化方案，并确定 EV RNA 货物（尤其是 microRNAs，miRNAs）是否具有 MDD 特异性特征。
从死后人脑组织中分离 EVs。使用 Western blot、透射电子显微镜和微流控电阻脉冲感应来评估质量。从 Illumina 平台上提取和测序 EV RNA。进行了计算机模拟的功能后续研究。
质量评估显示 EV 标志物的富集，以及直径为 30 至 200nm 的大小分布，并且没有细胞碎片的污染。小 RNA 分析表明存在几种 RNA 生物类型，其中 miRNAs 和转移 RNA 最为突出。探索组间 miRNA 水平表明，miR-92a-3p 和 miR-129-5p 的表达降低，通过 qPCR 进行了验证，并且仅存在于 EV 中，而不在大块组织中发现。最后，计算机模拟功能分析表明这 2 种 miRNA 在神经递质传递和突触可塑性中可能发挥作用。
我们提供了一种简化的分离方案，可产生高质量的 EV，适合进行分子研究。我们的发现表明，未来有必要研究 MDD 中脑 EV miRNA 失调。
