Transcriptional profiling of astrocytes in the prefrontal cortex, hippocampus, accumbens nucleus and caudate putamen of a Aldh1l1-TRAP (JD130) mouse line after chronic social defeat stress

Psychiatric disorders, especially major depressive disorder, are prominent cause of disability worldwide, and in dire need of better diagnostic and therapeutic tools. In order to identify the cellular mechanisms underlying major depressive disorder we sought to understand the role of astrocytes, the most numerous subtype of glia, in this disease utilizing the TRAP gene expression analysis and chronic social defeat mouse model of depression. TRAP translational profiling is a method that allows investigators to genetically characterize specific cell types in complex tissues such as mouse brain. Using this technique we obtained RNA-Seq data from actively translating transcripts present in astrocytes. We generated the molecular profile of astrocytes from multiple brain regions affected by stress-induced depression, the prefrontal cortex, hippocampus, accumbens nucleus and caudate putamen of adult Aldh1l1-EGFP/Rpl10a (JD130) mice after chronic social defeat stress paradigm. The results of this study will further our understanding of depression pathophysiology and will provide possible targets for novel or supplementary therapies. Adult Aldh1l1-EGFP/Rpl10a (JD130) mice were subjected to 10 days of social defeat and screened for social interaction (SI). They were divided in three groups based on their SI index: control-CTRL (no stress exposure, but present in the same environment-room, SI>1), resilient-RS (exposed to stress but showing no depressive-like symptoms, SI >1) and stress susceptible-SS (showing low social interaction index as a measure of depressive-like symptoms, SI<1). Two days after the last day of social defeat TRAP-Seq of astrocytes isolated from the prefrontal cortex (PFC), hippocampus (HIP), accumbens nucleus (NAC) and caudate putamen (CPU) was performed. Each biological replicate sample contained pooled regions isolated from 2 (for PFC, HIP and CPU) or 4-6 (for NAC) mice. The bioinformatics analysis was done comparing gene expression datasets from CTRL, RS, and SS mice. Genes showing significant change in expression in SS compared to RS and CTRL were further analyzed.精神类疾病，尤其是重度抑郁症（Major Depressive Disorder），是全球范围内导致残疾的主要诱因，目前亟需更完善的诊断与治疗工具。为明确重度抑郁症的细胞机制，本研究借助TRAP基因表达分析与慢性社交挫败抑郁小鼠模型，探究了星形胶质细胞——即数量最多的神经胶质细胞亚型——在该疾病中的作用。TRAP翻译组分析是一种可使研究者对小鼠脑组织等复杂组织中的特定细胞类型开展遗传特征鉴定的技术。本研究利用该技术，从星形胶质细胞的活跃翻译转录本中获取了RNA测序（RNA-Seq）数据。我们从经慢性社交挫败应激范式处理的成年Aldh1l1-EGFP/Rpl10a（JD130）小鼠的多个受应激诱导抑郁影响的脑区（前额叶皮层、海马体、伏隔核与尾状壳核）中，获取了星形胶质细胞的分子表达谱。本研究结果将深化我们对抑郁症病理生理学的认知，并可为新型或辅助治疗手段提供潜在靶点。 对成年Aldh1l1-EGFP/Rpl10a（JD130）小鼠施加了为期10天的社交挫败应激，并通过社交互动（Social Interaction, SI）实验完成筛选。研究人员根据其社交互动指数将小鼠分为三组：对照组（CTRL，未暴露于应激环境，但饲养于同一饲养舱中，SI>1）、应激抵抗组（RS，经应激暴露但未表现出抑郁样症状，SI>1）以及应激易感组（SS，社交互动指数较低，符合抑郁样症状判定标准，SI<1）。末次社交挫败应激两天后，我们对从前额叶皮层（Prefrontal Cortex, PFC）、海马体（Hippocampus, HIP）、伏隔核（Accumbens Nucleus, NAC）与尾状壳核（Caudate Putamen, CPU）中分离得到的星形胶质细胞开展了TRAP-Seq实验。每个生物学重复样本均混合了从2只（前额叶皮层、海马体与尾状壳核组）或4-6只（伏隔核组）小鼠中分离得到的对应脑区组织。生物信息学分析环节比对了对照组、应激抵抗组与应激易感组小鼠的基因表达数据集，并对相较于应激抵抗组与对照组，应激易感组中表达量存在显著差异的基因进行了后续分析。