Tan Huijun, Liu Yuelin, Guo Hongwei
Shenzhen Key Laboratory of Plant Genetic Engineering and Molecular Design, Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China.
Acta Biochim Biophys Sin (Shanghai). 2024 Sep 29;57(1):131-147. doi: 10.3724/abbs.2024160.
Small RNA (sRNA)-mediated RNA interference (RNAi) is a sequence-specific gene silencing mechanism that modulates gene expression in eukaryotes. As core molecules of RNAi, various sRNAs are encoded in the plant genome or derived from invading RNA molecules, and their biogenesis depends on distinct genetic pathways. Transitive small interfering RNAs (siRNAs), which are sRNAs produced from double-strand RNA (dsRNA) in a process that depends on RNA-dependent RNA polymerases (RDRs), can amplify and spread silencing signals to additional transcripts, thereby enabling a phenomenon termed "transitive RNAi". Members of this class of siRNAs function in various biological processes ranging from development to stress adaptation. In , two RDRs participate in the generation of transitive siRNAs, acting cooperatively with various siRNA generation-related factors, such as the RNA-induced silencing complex (RISC) and aberrant RNAs. Transitive siRNAs are produced in diverse subcellular locations and structures under the control of various mechanisms, highlighting the intricacies of their biogenesis and functions. In this review, we discuss recent advances in understanding the molecular events of transitive siRNA biogenesis and its regulation, with a particular focus on factors involved in RDR recruitment. We aim to provide a comprehensive description of the generalized mechanism governing the biogenesis of transitive siRNAs. Additionally, we present an overview of the diverse biological functions of these siRNAs and raise some pressing questions in this area for further investigation.
小RNA（sRNA）介导的RNA干扰（RNAi）是一种序列特异性的基因沉默机制，可调节真核生物中的基因表达。作为RNAi的核心分子，各种sRNA在植物基因组中编码或来源于入侵的RNA分子，其生物合成依赖于不同的遗传途径。传递性小干扰RNA（siRNA）是在依赖RNA的RNA聚合酶（RDR）的过程中由双链RNA（dsRNA）产生的sRNA，它可以将沉默信号扩增并传播到其他转录本，从而产生一种称为“传递性RNAi”的现象。这类siRNA成员在从发育到应激适应的各种生物学过程中发挥作用。在植物中，两种RDR参与传递性siRNA的产生，与各种与siRNA产生相关的因子协同作用，如RNA诱导沉默复合体（RISC）和异常RNA。传递性siRNA在各种机制的控制下在不同的亚细胞位置和结构中产生，突出了其生物合成和功能的复杂性。在这篇综述中，我们讨论了在理解传递性siRNA生物合成及其调控的分子事件方面的最新进展，特别关注参与RDR招募的因子。我们旨在全面描述控制传递性siRNA生物合成的一般机制。此外，我们概述了这些siRNA的多种生物学功能，并提出了该领域一些亟待进一步研究的问题。
