Provenzano Giovanni, Corradi Zelia, Monsorno Katia, Fedrizzi Tarcisio, Ricceri Laura, Scattoni Maria L, Bozzi Yuri
Laboratory of Molecular Neuropathology, Centre for Integrative Biology, University of Trento Trento, Italy.
Bioinformatics Core Facility, Centre for Integrative Biology, University of Trento Trento, Italy.
Front Neurosci. 2016 Aug 25;10:396. doi: 10.3389/fnins.2016.00396. eCollection 2016.
Autism spectrum disorders (ASD) are characterized by a high degree of genetic heterogeneity. Genomic studies identified common pathological processes underlying the heterogeneous clinical manifestations of ASD, and transcriptome analyses revealed that gene networks involved in synapse development, neuronal activity, and immune function are deregulated in ASD. Mouse models provide unique tools to investigate the neurobiological basis of ASD; however, a comprehensive approach to identify transcriptional abnormalities in different ASD models has never been performed. Here we used two well-recognized ASD mouse models, BTBR T(+) Itpr3 (tf) /J (BTBR) and Engrailed-2 knockout (En2 (-/-)), to identify conserved ASD-related molecular signatures. En2 (-/-) mice bear a mutation within the EN2 transcription factor homeobox, while BTBR is an inbred strain with unknown genetic defects. Hippocampal RNA samples from BTBR, En2 (-/-) and respective control (C57Bl/6J and En2 (+/+)) adult mice were assessed for differential gene expression using microarrays. A total of 153 genes were similarly deregulated in the BTBR and En2 (-/-) hippocampus. Mouse phenotype and gene ontology enrichment analyses were performed on BTBR and En2 (-/-) hippocampal differentially expressed genes (DEGs). Pathways represented in both BTBR and En2 (-/-) hippocampal DEGs included abnormal behavioral response and chemokine/MAP kinase signaling. Genes involved in abnormal function of the immune system and abnormal synaptic transmission/seizures were significantly represented among BTBR and En2 (-/-) DEGs, respectively. Interestingly, both BTBR and En2 (-/-) hippocampal DEGs showed a significant enrichment of ASD and schizophrenia (SCZ)-associated genes. Specific gene sets were enriched in the two models: microglial genes were significantly enriched among BTBR DEGs, whereas GABAergic/glutamatergic postsynaptic genes, FMRP-interacting genes and epilepsy-related genes were significantly enriched among En2 (-/-) DEGs. Weighted correlation network analysis (WGCNA) performed on BTBR and En2 (-/-) hippocampal transcriptomes together identified six modules significantly enriched in ASD-related genes. Each of these modules showed a specific enrichment profile in neuronal and glial genes, as well as in genes associated to ASD comorbidities such as epilepsy and SCZ. Our data reveal significant transcriptional similarities and differences between the BTBR and En2 (-/-) hippocampus, indicating that transcriptome analysis of ASD mouse models may contribute to identify novel molecular targets for pharmacological studies.
自闭症谱系障碍（ASD）的特征是高度的遗传异质性。基因组研究确定了ASD异质临床表现背后的常见病理过程，转录组分析表明，参与突触发育、神经元活动和免疫功能的基因网络在ASD中失调。小鼠模型为研究ASD的神经生物学基础提供了独特的工具；然而，从未采用过全面的方法来识别不同ASD模型中的转录异常。在这里，我们使用了两种广为人知的ASD小鼠模型，BTBR T(+) Itpr3 (tf) /J（BTBR）和 engrailed-2基因敲除小鼠（En2 (-/-)），以识别与ASD相关的保守分子特征。En2 (-/-)小鼠在EN2转录因子同源框内有一个突变，而BTBR是一个具有未知遗传缺陷的近交系。使用微阵列评估来自BTBR、En2 (-/-)以及各自对照（C57Bl/6J和En2 (+/+))成年小鼠的海马RNA样本的差异基因表达。共有153个基因在BTBR和En2 (-/-)海马体中同样失调。对BTBR和En2 (-/-)海马体差异表达基因（DEG）进行小鼠表型和基因本体富集分析。BTBR和En2 (-/-)海马体DEG中代表的通路包括异常行为反应和趋化因子/丝裂原活化蛋白激酶信号传导。在BTBR和En2 (-/-) DEG中，分别显著代表了参与免疫系统异常功能和异常突触传递/癫痫发作的基因。有趣的是，BTBR和En2 (-/-)海马体DEG均显示出与ASD和精神分裂症（SCZ）相关基因的显著富集。特定的基因集在这两种模型中富集：小胶质细胞基因在BTBR DEG中显著富集，而γ-氨基丁酸能/谷氨酸能突触后基因、脆性X智力低下蛋白（FMRP）相互作用基因和癫痫相关基因在En2 (-/-) DEG中显著富集。对BTBR和En2 (-/-)海马体转录组进行的加权相关网络分析（WGCNA）共同确定了六个在与ASD相关基因中显著富集的模块。这些模块中的每一个在神经元和神经胶质基因以及与ASD合并症（如癫痫和SCZ）相关的基因中都显示出特定的富集谱。我们的数据揭示了BTBR和En2 (-/-)海马体之间显著的转录相似性和差异，表明对ASD小鼠模型的转录组分析可能有助于识别药理学研究的新分子靶点。
