College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
Int J Mol Sci. 2021 Jun 18;22(12):6537. doi: 10.3390/ijms22126537.
Rabies virus (RABV) induces acute, fatal encephalitis in mammals including humans. The circRNAs are important in virus infection process, but whether circRNAs regulated RABV infection remains largely unknown. Here, mice brain with or without the RABV CVS-11 strain were subjected to RNA sequencing and a total of 30,985 circRNAs were obtained. Among these, 9021 candidates were shared in both groups, and 14,610 and 7354 circRNAs were expressed specifically to the control and experimental groups, indicating that certain circRNAs were specifically inhibited or induced on RABV infection. The circRNAs mainly derived from coding exons. In total, 636 circRNAs were differentially expressed in RABV infection, of which 426 significantly upregulated and 210 significantly downregulated ( < 0.05 and fold change ≥2). The expression of randomly selected 6 upregulated and 6 downregulated circRNAs was tested by RT-qPCR, and the expression trend of the 11 out of 12 circRNAs was consistent in RT- qPCR and RNA-seq analysis. Rnase R-resistant assay and Sanger sequencing were conducted to verify the circularity of circRNAs. GO analysis demonstrated that source genes of all differentially regulated circRNAs were mainly related to cell plasticity and synapse function. Both KEGG and GSEA analysis revealed that these source genes were engaged in the cGMP-PKG and MAPK signaling pathway, and HTLV-I infection. Also, pathways related to glucose metabolism and synaptic functions were enriched in KEGG analysis. The circRNA-miRNA-mRNA network was built with 25 of 636 differentially expressed circRNAs, 264 mRNAs involved in RABV infection, and 29 miRNAs. Several miRNAs and many mRNAs in the network were reported to be related to viral infection and the immune response, suggesting that circRNAs could regulate RABV infection via interacting with miRNAs and mRNAs. Taken together, this study first characterized the transcriptomic pattern of circRNAs, and signaling pathways and function that circRNAs are involved in, which may indicate directions for further research to understand mechanisms of RABV pathogenesis.
狂犬病病毒（RABV）可诱导包括人类在内的哺乳动物发生急性致命性脑炎。 circRNAs 在病毒感染过程中具有重要作用，但 circRNAs 是否调控 RABV 感染尚不清楚。本研究中，对感染或未感染 RABV CVS-11 株的小鼠脑组织进行 RNA 测序，共获得 30985 个 circRNAs。其中，两组共有 9021 个候选 circRNAs，对照组和实验组特异性表达的分别为 14610 个和 7354 个，提示特定 circRNAs 在 RABV 感染时被特异性抑制或诱导。circRNAs 主要来源于编码外显子。在 RABV 感染中，共检测到 636 个差异表达的 circRNAs，其中 426 个显著上调，210 个显著下调（<0.05，倍数变化≥2）。通过 RT-qPCR 检测了随机选择的 6 个上调和 6 个下调 circRNAs 的表达情况，在 RT-qPCR 和 RNA-seq 分析中，12 个 circRNAs 的表达趋势一致。通过 RNase R 抗性试验和 Sanger 测序验证了 circRNAs 的环状结构。GO 分析表明，所有差异调节 circRNAs 的来源基因主要与细胞可塑性和突触功能相关。KEGG 和 GSEA 分析均显示，这些来源基因参与 cGMP-PKG 和 MAPK 信号通路以及 HTLV-I 感染。KEGG 分析中还富集了与葡萄糖代谢和突触功能相关的通路。构建了包含 636 个差异表达 circRNAs、264 个与 RABV 感染相关的 mRNAs 和 29 个 miRNAs 的 circRNA-miRNA-mRNA 网络。网络中的一些 miRNAs 和许多 mRNAs 已被报道与病毒感染和免疫反应有关，提示 circRNAs 可能通过与 miRNAs 和 mRNAs 相互作用来调节 RABV 感染。综上所述，本研究首次对 circRNAs 的转录组图谱、参与的信号通路和功能进行了描述，为进一步研究 RABV 发病机制提供了方向。
