Cao Song, Deng Wenwen, Li Ying, Qin Bangyong, Zhang Lin, Yu Shouyang, Xie Peng, Xiao Zhi, Yu Tian
Department of Pain Medicine, Affiliated Hospital of Zunyi Medical University.
Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University.
J Pain Res. 2017 Jul 17;10:1687-1696. doi: 10.2147/JPR.S139592. eCollection 2017.
Mechanisms of neuropathic pain are still largely unknown. Molecular changes in spinal dorsal horn may contribute to the initiation and development of neuropathic pain. Circular RNAs (circRNAs) have been identified as microRNA sponges and involved in various biological processes, but whether their expression profile changes in neuropathic pain condition is not reported.
To test whether neuropathic pain influences circRNA expression, we developed a sciatic chronic constriction injury (CCI) model in rats. The CCI ipsilateral spinal dorsal horns of lumbar enlargement segments (L3-L5) were collected, and the total RNA was extracted and subjected to Arraystar Rat circRNA Microarray. Quantitative real-time polymerase chain reaction (qPCR) was used to confirm the circRNA expression profile. To estimate functions of differential circRNAs, bioinformatics analyses including gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes Pathway analyses were performed for the top 100 circRNAs and circRNA-microRNA networks were constructed for the top 10 circRNAs.
circRNA microarrays showed that 469 circRNAs were differentially expressed between CCI and sham-operated rats (fold change ≥2). In all, 363 of them were significantly upregulated, and the other 106 were downregulated in the CCI group. Three of them (circRNA_013779, circRNA_008008, and circRNA_003724) overexpressed >10 times after CCI insult. Expression levels of eight circRNAs were verified using qPCR. GO analysis revealed that thousands of predicted target genes were involved in the biological processes, cellular component, and molecular function; in addition, dozens of these genes were enriched in the Hippo signaling pathway, MAPK signaling pathway, and so on. Competing endogenous RNAs analysis showed that circRNA_008008 and circRNA_013779 are the two largest nodes in the circRNA-microRNA interaction network of the top 10 circRNAs.
CCI resulted in a comprehensive expression profile of circRNAs in the spinal dorsal horn in rats. CircRNAs in the dorsal horn could be helpful to reveal molecular mechanisms of neuropathic pain.
神经性疼痛的机制在很大程度上仍不清楚。脊髓背角的分子变化可能有助于神经性疼痛的起始和发展。环状RNA（circRNAs）已被鉴定为微小RNA海绵，并参与各种生物学过程，但它们在神经性疼痛状态下的表达谱是否发生变化尚未见报道。
为了检测神经性疼痛是否影响circRNA表达，我们在大鼠中建立了坐骨神经慢性压迫损伤（CCI）模型。收集CCI同侧腰膨大节段（L3-L5）的脊髓背角，提取总RNA并进行Arraystar大鼠circRNA芯片检测。采用定量实时聚合酶链反应（qPCR）来确认circRNA表达谱。为了评估差异circRNA的功能，对前100个circRNA进行了包括基因本体（GO）和京都基因与基因组百科全书通路分析在内的生物信息学分析，并为前10个circRNA构建了circRNA-微小RNA网络。
circRNA芯片显示，CCI组和假手术组大鼠之间有469个circRNA差异表达（倍数变化≥2）。其中，363个在CCI组中显著上调，另外106个下调。CCI损伤后，其中3个（circRNA_013779、circRNA_008008和circRNA_003724）的表达上调超过10倍。使用qPCR验证了8个circRNA的表达水平。GO分析显示，数千个预测的靶基因参与了生物学过程、细胞成分和分子功能；此外，其中数十个基因在Hippo信号通路、MAPK信号通路等中富集。竞争性内源RNA分析表明，circRNA_008008和circRNA_013779是前10个circRNA的circRNA-微小RNA相互作用网络中的两个最大节点。
CCI导致大鼠脊髓背角circRNA的全面表达谱。背角中的circRNA可能有助于揭示神经性疼痛的分子机制。
