Stepien Agata, Knop Katarzyna, Dolata Jakub, Taube Michal, Bajczyk Mateusz, Barciszewska-Pacak Maria, Pacak Andrzej, Jarmolowski Artur, Szweykowska-Kulinska Zofia
Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland.
Wiley Interdiscip Rev RNA. 2017 May;8(3). doi: 10.1002/wrna.1403. Epub 2016 Nov 9.
MicroRNAs (miRNAs) are short, single-stranded, noncoding RNAs that play a crucial role in basic physiological and morphological processes and in response to various stresses in eukaryotic organisms. However, the miRNA biogenesis, which is based on the action of complex protein machinery, varies between plants and animals, with the differences largely concerning the location of the process, the protein composition of the microprocessor, the mechanism of miRNA action on mRNA target, and the miRNA gene (MIR) structure. Roughly half of known Arabidopsis MIRs contain introns, and 29 miRNAs are encoded within the introns of host genes. Selection of alternative transcription start sites, alternative splice sites (SSs), and polyadenylation sites has been identified within miRNA primary transcripts (pri-miRNAs), and such variety is essential for the production and fine-tuning of miRNA levels. For example, the posttranscriptional processing of intron-containing pri-miRNAs involves the action of additional RNA metabolism machineries, such as the spliceosome and polyadenylation machinery, and to a large extent is based on direct communication between SERRATE (one of the core components of the plant microprocessor) and U1 snRNP auxiliary proteins. Moreover, the position of the miRNA stem-loop structure relative to the closest active 5'SS is essential for the miRNA production efficiency. Indeed, it is highly probable that this pre-miRNA location affects recruitment of the microprocessor to pri-miRNAs and therefore influences miRNA maturation and target mRNA regulation. Such complicated crosstalk between several machineries is important for a proper miRNA-connected response to biotic and abiotic stresses, ensuring plant survival in a changing environment. WIREs RNA 2017, 8:e1403. doi: 10.1002/wrna.1403 For further resources related to this article, please visit the WIREs website.
微小RNA（miRNA）是短的单链非编码RNA，在真核生物的基本生理和形态过程以及对各种应激的反应中发挥关键作用。然而，基于复杂蛋白质机制作用的miRNA生物合成在植物和动物之间存在差异，差异主要涉及该过程的位置、微处理器的蛋白质组成、miRNA对mRNA靶标的作用机制以及miRNA基因（MIR）结构。大约一半已知的拟南芥MIR含有内含子，并且29个miRNA在宿主基因的内含子中编码。在miRNA初级转录本（pri-miRNA）中已鉴定出可变转录起始位点、可变剪接位点（SS）和聚腺苷酸化位点的选择，这种多样性对于miRNA水平的产生和微调至关重要。例如，含内含子的pri-miRNA的转录后加工涉及额外的RNA代谢机制的作用，如剪接体和聚腺苷酸化机制，并且在很大程度上基于锯齿蛋白（植物微处理器的核心成分之一）与U1 snRNP辅助蛋白之间的直接通讯。此外，miRNA茎环结构相对于最接近的活性5'SS的位置对于miRNA产生效率至关重要。事实上，这种前体miRNA的位置很可能影响微处理器对pri-miRNA的招募，因此影响miRNA成熟和靶标mRNA调控。几种机制之间如此复杂的串扰对于与miRNA相关的对生物和非生物胁迫的适当反应很重要，确保植物在不断变化的环境中生存。WIREs RNA 2017, 8:e1403. doi: 10.1002/wrna.1403 有关本文的更多资源，请访问WIREs网站。
