Pegler Joseph L, Grof Christopher P L, Eamens Andrew L
Faculty of Science, Centre for Plant Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, Australia.
Methods Mol Biol. 2019;1932:15-39. doi: 10.1007/978-1-4939-9042-9_2.
Plant microRNAs are an endogenous class of small regulatory RNA central to the posttranscriptional regulation of gene expression in plant development and environmental stress adaptation or in response to pathogen challenge. The plant microRNA pathway is readily separated into two distinct stages: (1) the production stage, which is localized to the plant cell nucleus and where the microRNA small RNA is processed from a double-stranded RNA precursor transcript, and (2) the action stage, which is localized to the plant cell cytoplasm and where the mature microRNA small RNA is loaded into an effector complex and is used by the complex as a sequence specificity guide to direct expression repression of target genes harboring highly complementary microRNA target sequences. Historical research indicated that the plant microRNA pathway was a highly structured, almost linear pathway requiring a small set of core machinery proteins. However, contemporary research has demonstrated that the plant microRNA pathway is highly dynamic, and to allow for this flexibility, a large and highly functionally diverse set of machinery proteins is now known to be required. For example, recent research has shown that plant microRNAs can regulate target gene expression via a translational repression mechanism of RNA silencing in addition to the standard messenger RNA cleavage-based mechanism of RNA silencing: a mode of RNA silencing originally assigned to all plant microRNAs. Using Arabidopsis thaliana as our model system, here we report on both the core and auxiliary sets of machinery proteins now known to be required for both microRNA production and microRNA action in plants.
植物微小RNA是一类内源性小调控RNA，在植物发育、环境胁迫适应或应对病原体挑战过程中，对基因表达的转录后调控起着核心作用。植物微小RNA途径可很容易地分为两个不同阶段：（1）产生阶段，定位于植物细胞核，在此微小RNA小RNA从双链RNA前体转录本加工而来；（2）作用阶段，定位于植物细胞质，在此成熟的微小RNA小RNA被装载到效应复合物中，并被该复合物用作序列特异性指导，以直接抑制具有高度互补微小RNA靶序列的靶基因的表达。以往的研究表明，植物微小RNA途径是一条高度结构化、近乎线性的途径，需要一小套核心机制蛋白。然而，当代研究表明，植物微小RNA途径具有高度动态性，为实现这种灵活性，现已知道需要一大套功能高度多样的机制蛋白。例如，最近的研究表明，植物微小RNA除了通过基于信使核糖核酸切割的标准RNA沉默机制外，还可通过RNA沉默的翻译抑制机制调控靶基因表达：RNA沉默的这种模式最初被认为适用于所有植物微小RNA。以拟南芥作为我们的模型系统，在此我们报告了现已知道在植物微小RNA产生和微小RNA作用过程中所需的机制蛋白的核心集和辅助集。
