Mitochondria participate in varieties of cellular events. It is widely accepted that human mitochondrial genome encodes 13 proteins, 2 rRNAs, and 22 tRNAs. Gene variation derived from human nuclear genome cannot completely explain mitochondrial diseases. The advent of high-throughput sequencing coupled with novel bioinformatic analyses decode the complexity of mitochondria-derived transcripts. Recently, circular RNAs (circRNAs) from both human mitochondrial genome and nuclear genome have been found to be located at mitochondria. Studies about the roles and molecular mechanisms underlying trafficking of the nucleus encoded circRNAs to mitochondria and mitochondria encoded circRNAs to the nucleus or cytoplasm in mammals are only beginning to emerge. These circRNAs have been associated with a variety of diseases, especially cancers. Here, we discuss the emerging field of mitochondria-located circRNAs by reviewing their identification, expression patterns, regulatory roles, and functional mechanisms. Mitochondria-located circRNAs have regulatory roles in cellular physiology and pathology. We also highlight future perspectives and challenges in studying mitochondria-located circRNAs, as well as their potential biomedical applications.

中文翻译：

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CircRNA 在线粒体中的作用

线粒体参与多种细胞事件。人们普遍认为，人类线粒体基因组编码 13 种蛋白质、2 种 rRNA 和 22 种 tRNA。来自人类核基因组的基因变异不能完全解释线粒体疾病。高通量测序的出现与新颖的生物信息学分析相结合，解码了线粒体衍生转录本的复杂性。最近，来自人类线粒体基因组和核基因组的环状RNA（circRNA）被发现位于线粒体。关于哺乳动物细胞核编码的 circRNA 运输到线粒体以及线粒体编码的 circRNA 运输到细胞核或细胞质的作用和分子机制的研究才刚刚开始出现。这些 circRNA 与多种疾病有关，尤其是癌症。在这里，我们通过回顾位于线粒体的 circRNA 的鉴定、表达模式、调节作用和功能机制来讨论新兴领域。位于线粒体的 circRNA 在细胞生理学和病理学中具有调节作用。我们还强调了研究位于线粒体的 circRNA 及其潜在生物医学应用的未来前景和挑战。