Lezzhov Alexander A, Atabekova Anastasia K, Chergintsev Denis A, Lazareva Ekaterina A, Solovyev Andrey G, Morozov Sergey Y
A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, 119992 Moscow, Russia.
Plants (Basel). 2024 Dec 27;14(1):61. doi: 10.3390/plants14010061.
Among the long non-coding RNAs that are currently recognized as important regulatory molecules influencing a plethora of processes in eukaryotic cells, circular RNAs (circRNAs) represent a distinct class of RNAs that are predominantly produced by back-splicing of pre-mRNA. The most studied regulatory mechanisms involving circRNAs are acting as miRNA sponges, forming R-loops with genomic DNA, and encoding functional proteins. In addition to circRNAs generated by back-splicing, two types of circRNAs capable of autonomous RNA-RNA replication and systemic transport have been described in plants: viroids, which are infectious RNAs that cause a number of plant diseases, and retrozymes, which are transcripts of retrotransposon genomic loci that are capable of circularization due to ribozymes. Based on a number of common features, viroids and retrozymes are considered to be evolutionarily related. Here, we provide an overview of the biogenesis mechanisms and regulatory functions of non-replicating circRNAs produced by back-splicing and further discuss in detail the currently available data on viroids and retrozymes, focusing on their structural features, replication mechanisms, interaction with cellular components, and transport in plants. In addition, biotechnological approaches involving replication-capable plant circRNAs are discussed, as well as their potential applications in research and agriculture.
在目前被认为是影响真核细胞众多过程的重要调控分子的长链非编码RNA中，环状RNA（circRNA）是一类独特的RNA，主要由前体mRNA的反向剪接产生。目前研究最多的涉及circRNA的调控机制包括充当miRNA海绵、与基因组DNA形成R环以及编码功能蛋白。除了通过反向剪接产生的circRNA外，植物中还描述了两种能够自主进行RNA-RNA复制和系统运输的circRNA：类病毒，一种能引起多种植物病害的感染性RNA；逆转录酶，一种逆转座子基因组位点的转录本，由于核酶作用能够环化。基于一些共同特征，类病毒和逆转录酶被认为在进化上相关。在这里，我们概述了通过反向剪接产生的非复制性circRNA的生物发生机制和调控功能，并进一步详细讨论了目前关于类病毒和逆转录酶的可用数据，重点关注它们的结构特征、复制机制、与细胞成分的相互作用以及在植物中的运输。此外，还讨论了涉及具有复制能力的植物circRNA的生物技术方法，以及它们在研究和农业中的潜在应用。
