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microRNAs (miRNAs) play crucial roles in numerous developmental and metabolic processes in plants and animals. The steady-state levels of miRNAs need to be properly controlled to ensure normal development. Whereas the framework of miRNA biogenesis is established, factors involved in miRNA degradation remain unknown. Here, we show that a family of exoribonucleases encoded by the SMALL RNA DEGRADING NUCLEASE (SDN) genes degrades mature miRNAs in Arabidopsis. SDN1 acts specifically on single-stranded miRNAs in vitro and is sensitive to the 2'-O-methyl modification on the 3' terminal ribose of miRNAs. Simultaneous knockdown of three SDN genes in vivo results in elevated miRNA levels and pleiotropic developmental defects. Therefore, we have uncovered the enzymes that degrade miRNAs and demonstrated that miRNA turnover is crucial for plant development. 相似文献
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In the Drosophila germline, repeat-associated small interfering RNAs (rasiRNAs) ensure genomic stability by silencing endogenous selfish genetic elements such as retrotransposons and repetitive sequences. Whereas small interfering RNAs (siRNAs) derive from both the sense and antisense strands of their double-stranded RNA precursors, rasiRNAs arise mainly from the antisense strand. rasiRNA production appears not to require Dicer-1, which makes microRNAs (miRNAs), or Dicer-2, which makes siRNAs, and rasiRNAs lack the 2',3' hydroxy termini characteristic of animal siRNA and miRNA. Unlike siRNAs and miRNAs, rasiRNAs function through the Piwi, rather than the Ago, Argonaute protein subfamily. Our data suggest that rasiRNAs protect the fly germline through a silencing mechanism distinct from both the miRNA and RNA interference pathways. 相似文献
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Elucidation of the small RNA component of the transcriptome 总被引：3，自引：0，他引：3
Lu C Tej SS Luo S Haudenschild CD Meyers BC Green PJ 《Science (New York, N.Y.)》2005,309(5740):1567-1569
Small RNAs play important regulatory roles in most eukaryotes, but only a small proportion of these molecules have been identified. We sequenced more than two million small RNAs from seedlings and the inflorescence of the model plant Arabidopsis thaliana. Known and new microRNAs (miRNAs) were among the most abundant of the nonredundant set of more than 75,000 sequences, whereas more than half represented lower abundance small interfering RNAs (siRNAs) that match repetitive sequences, intergenic regions, and genes. Individual or clusters of highly regulated small RNAs were readily observed. Targets of antisense RNA or miRNA did not appear to be preferentially associated with siRNAs. Many genomic regions previously considered featureless were found to be sites of numerous small RNAs. 相似文献
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A microRNA in a multiple-turnover RNAi enzyme complex 总被引：2，自引：0，他引：2
In animals, the double-stranded RNA-specific endonuclease Dicer produces two classes of functionally distinct, tiny RNAs: microRNAs (miRNAs) and small interfering RNAs (siRNAs). miRNAs regulate mRNA translation, whereas siRNAs direct RNA destruction via the RNA interference (RNAi) pathway. Here we show that, in human cell extracts, the miRNA let-7 naturally enters the RNAi pathway, which suggests that only the degree of complementarity between a miRNA and its RNA target determines its function. Human let-7 is a component of a previously identified, miRNA-containing ribonucleoprotein particle, which we show is an RNAi enzyme complex. Each let-7-containing complex directs multiple rounds of RNA cleavage, which explains the remarkable efficiency of the RNAi pathway in human cells. 相似文献
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真核细胞中存在大量的非编码RNA,～22nt的小RNA是其中一类非常重要的调控RNA,主要包括siRNA和miRNA两种类型,二者均由类似RNaseⅢ的核酸内切酶一Dicer加工产生,随后进入沉默复合体抑制靶基因表达。miRNA分子与siRNA类似,但miRNA的前体在基因组上具有独立的转录单位,可自身折叠成发卡结构,其靶基因主要是与器官发生及生长发育相关的转录因子以及调控蛋白。miRNA在生物生长发育的各个时期都扮演着重要的角色,调控许多重要的生物途径,处于基因调控网络的核心位置。 相似文献
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microRNA(miRNA)是一类内源性表达的在转录后基因调控中发挥重要作用的小分子非编码RNA。在动植物细胞中,miRNA通过翻译抑制和靶mRNA去稳定性来调控靶基因,从而调控生长、发育、分化、死亡等生物过程。综述了miRNA的发现、形成、特点及调控机制。 相似文献
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Argonaute2 （Ago2）蛋白是RNA诱导沉默复合体（RNA-induced silencing complex、RISC）的核心元件,不仅在miRNA/siRNA通路中促使靶mRNA降解或抑制其蛋白质翻译,调节miRNAs生物合成和成熟,对生物生长发育、干细胞分化和肿瘤形成等有密切关系. 相似文献
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DAI Chen ZHANG Yan-ming ZHANG Qian WU Zong-song DENG Wen ZHANG Xu GUO Kang-kang TANG Qing-hai HOU Bo 《中国农业科学(英文版)》2011,10(9):1467-1474
MicroRNAs (miRNAs) are endogenous ∼22 nt RNAs that play important regulatory roles in targeting mRNAs for cleavage or translational repression. Despite the discovery of increasing numbers of human and mouse miRNAs, little is known about miRNAs from pig. In this study, we sought to extend the repertoire of porcine small regulatory RNAs using Solexa sequencing. We sequenced a library of small RNAs prepared from immortalized swine umbilical vein endothelial cells (SUVECs). We produced over 13.6 million short sequence reads, of which 8547658 perfectly mapped to the pig genome. A bioinformatics pipeline was used to identify authentic mature miRNA sequences. We identified 154 porcine miRNA genes, among which 146 were conserved across species, and 8 were pig-specific miRNA genes. The 146 miRNA genes encoded 116 conserved mature miRNAs and 66 miRNA*. The 8 pig-specific miRNA genes encoded 4 mature miRNAs. Four potential novel miRNAs were identified. The secondary structures of the 154 miRNA genes were predicted; 13 miRNAs have 2 structures, and miR-9 and miR-199 have 4 and 3 structures, respectively. 36 miRNAs were organized into 19 compact clusters. miR-206, miR-21 and miR-378 were the relatively highly expressed miRNAs. In conclusion, Solexa sequencing allowed the successful discovery of known and novel porcine miRNAs with high accuracy and efficiency. Furthermore, our results supply new data to the somewhat insufficient pig miRBase, and are useful for investigating features of the blood-brain barrier, vascular diseases and inflammation. 相似文献
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MicroRNA(miRNA)是一类内源性的、长度约18～24 nt、非编码、单链小RNA分子,miRNA广泛存在于各种动植物体内,并参与基因表达的调控。随着植物miRNA研究的不断发展,越来越多的miRNA被证实在不同的非生物逆境下具有重要的调控作用,例如营养胁迫、低温胁迫、机械胁迫等。该文综述了植物miRNA的合成、miRNA及其靶基因的鉴定方法,并重点介绍了非生物逆境相关miRNA的表达分析方法、逆境条件下miRNA的调控特征及其靶基因特点等。 相似文献
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Genome-wide characterization of miRNA and siRNA pathways in the parasitoid wasp Pteromalus puparum 
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下载免费PDF全文 XIAO Shan FANG Qi LIU Ming-ming ZHANG Jiao WANG Bei-bei YAN Zhi-chao WANG Fang David W. STANLEY YE Gong-yin 《农业科学学报》2022,21(4):1106-1115
microRNAs (miRNAs) and small interfering RNAs (siRNAs) are small non-coding RNAs (ncRNAs) that trigger RNA interference (RNAi) in eukaryotic organisms. The biogenesis pathways for these ncRNAs are well established in Drosophila melanogaster, Aedes aegypti, Bombyx mori and other insects, but lacking in hymenopteran species, particularly in parasitoid wasps. Pteromalus puparum is a parasitoid of pupal butterflies. This study identified and analyzed two pathways by interrogating the P. puparum genome. All core genes of the two pathways are present in the genome as a single copy, except for two genes in the siRNA pathway, R2D2 (two copies) and Argonaute-2 (three). Conserved domain analyses showed the protein structures in P. puparum were similar to cognate proteins in other insect species. Phylogenetic analyses of hymenopteran Dicer and Argonaute genes suggested that the siRNA pathway-related genes evolved faster than those in the miRNA pathway. The study found a decelerated evolution rate of P. puparum Dicer-2 with respect to Dicer-1, which was contrary to other hymenopterans. Expression analyses revealed high mRNA levels for all miRNA pathway genes in P. puparum adults and the siRNA related genes were expressed in different patterns. The findings add valuable new knowledge of the miRNA and siRNA pathways and their regulatory actions in parasitoid wasps. 相似文献
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Nuclear export of microRNA precursors 总被引：2，自引：0，他引：2
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Role of microRNAs in plant and animal development 总被引：3，自引：0，他引：3
Small RNAs, including microRNAs (miRNAs) and short interfering RNAs (siRNAs), are key components of an evolutionarily conserved system of RNA-based gene regulation in eukaryotes. They are involved in many molecular interactions, including defense against viruses and regulation of gene expression during development. miRNAs interfere with expression of messenger RNAs encoding factors that control developmental timing, stem cell maintenance, and other developmental and physiological processes in plants and animals. miRNAs are negative regulators that function as specificity determinants, or guides, within complexes that inhibit protein synthesis (animals) or promote degradation (plants) of mRNA targets. 相似文献