Table_1_Identification and characterization of N6-methyladenosine circular RNAs in the spinal cord of morphine-tolerant rats.DOCX

Morphine tolerance (MT) is a tricky problem, the mechanism of it is currently unknown. Circular RNAs (circRNAs) serve significant functions in the biological processes (BPs) of the central nervous system. N6-methyladenosine (m6A), as a key post-transcriptional modification of RNA, can regulate the metabolism and functions of circRNAs. Here we explore the patterns of m6A-methylation of circRNAs in the spinal cord of morphine-tolerant rats. In brief, we constructed a morphine-tolerant rat model, performed m6A epitranscriptomic microarray using RNA samples collected from the spinal cords of morphine-tolerant rats and normal saline rats, and implemented the bioinformatics analysis. In the spinal cord of morphine-tolerant rats, 120 circRNAs with different m6A modifications were identified, 54 of which were hypermethylated and 66 of which were hypomethylated. Functional analysis of these m6A circRNAs found some important pathways involved in the pathogenesis of MT, such as the calcium signaling pathway. In the m6A circRNA-miRNA networks, several critical miRNAs that participated in the occurrence and development of MT were discovered to bind to these m6A circRNAs, such as miR-873a-5p, miR-103-1-5p, miR-107-5p. M6A modification of circRNAs may be involved in the pathogenesis of MT. These findings may lead to new insights into the epigenetic etiology and pathology of MT.

吗啡耐受（Morphine tolerance, MT）是一项棘手的临床问题，其具体发病机制目前仍未阐明。环状RNA（Circular RNAs, circRNAs）在中枢神经系统的各类生物学过程（biological processes, BPs）中发挥关键调控作用。N6-甲基腺嘌呤（N6-methyladenosine, m6A）作为一种重要的RNA转录后修饰方式，可调控环状RNA的代谢与功能。
本研究聚焦于吗啡耐受大鼠脊髓组织中环状RNA的m6A甲基化修饰模式。简言之，本研究构建了吗啡耐受大鼠模型，分别采集吗啡耐受大鼠与生理盐水对照组大鼠的脊髓组织RNA样本，开展表观转录组芯片检测，并进行生物信息学分析。
结果显示，在吗啡耐受大鼠脊髓组织中，共鉴定出120个存在差异m6A修饰的环状RNA，其中54个呈现高甲基化状态，66个呈现低甲基化状态。
对上述差异m6A修饰环状RNA进行功能分析后发现，多条与吗啡耐受发病机制相关的重要通路被富集，例如钙信号通路。
在构建的m6A修饰环状RNA-微小RNA（miRNA）调控网络中，本研究发现多个参与吗啡耐受发生发展的关键微小RNA可结合上述差异修饰的环状RNA，包括miR-873a-5p、miR-103-1-5p及miR-107-5p。
综上，环状RNA的m6A修饰可能参与吗啡耐受的发病过程，本研究结果可为吗啡耐受的表观遗传病因学与病理学研究提供全新的洞察视角。