共查询到20条相似文献，搜索用时 328 毫秒
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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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microRNAs(miRNAs)是真核生物中一类长度约为22 nt的非编码小分子RNA,miRNA与AGO等蛋白形成RISC沉默复合体,通过剪切或翻译抑制对靶基因起负调控作用。对拟南芥miRNA序列及其配对的靶序列间的特征进行了统计分析,结果表明miRNA序列5′端富含A、U,第1、第19碱基位对U、C具有较强的倾向性;miRNA与靶序列间常有1~4个碱基错配,错配碱基常出现在第1,第2和第21位,而第3~第6,第9~第10,第16~第17碱基配对较为保守,为人工合成miRNA的设计及miRNA靶基因的预测以提供了依据。 相似文献
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MicroRNAs modulate hematopoietic lineage differentiation 总被引：8，自引：0，他引：8
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Brodersen P Sakvarelidze-Achard L Bruun-Rasmussen M Dunoyer P Yamamoto YY Sieburth L Voinnet O 《Science (New York, N.Y.)》2008,320(5880):1185-1190
High complementarity between plant microRNAs (miRNAs) and their messenger RNA targets is thought to cause silencing, prevalently by endonucleolytic cleavage. We have isolated Arabidopsis mutants defective in miRNA action. Their analysis provides evidence that plant miRNA-guided silencing has a widespread translational inhibitory component that is genetically separable from endonucleolytic cleavage. We further show that the same is true of silencing mediated by small interfering RNA (siRNA) populations. Translational repression is effected in part by the ARGONAUTE proteins AGO1 and AGO10. It also requires the activity of the microtubule-severing enzyme katanin, implicating cytoskeleton dynamics in miRNA action, as recently suggested from animal studies. Also as in animals, the decapping component VARICOSE (VCS)/Ge-1 is required for translational repression by miRNAs, which suggests that the underlying mechanisms in the two kingdoms are related. 相似文献
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miRNA-mediated gene silencing by translational repression followed by mRNA deadenylation and decay 总被引：2，自引：0，他引：2
microRNAs (miRNAs) regulate gene expression through translational repression and/or messenger RNA (mRNA) deadenylation and decay. Because translation, deadenylation, and decay are closely linked processes, it is important to establish their ordering and thus to define the molecular mechanism of silencing. We have investigated the kinetics of these events in miRNA-mediated gene silencing by using a Drosophila S2 cell-based controllable expression system and show that mRNAs with both natural and engineered 3' untranslated regions with miRNA target sites are first subject to translational inhibition, followed by effects on deadenylation and decay. We next used a natural translational elongation stall to show that miRNA-mediated silencing inhibits translation at an early step, potentially translation initiation. 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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Ghildiyal M Seitz H Horwich MD Li C Du T Lee S Xu J Kittler EL Zapp ML Weng Z Zamore PD 《Science (New York, N.Y.)》2008,320(5879):1077-1081
Small interfering RNAs (siRNAs) direct RNA interference (RNAi) in eukaryotes. In flies, somatic cells produce siRNAs from exogenous double-stranded RNA (dsRNA) as a defense against viral infection. We identified endogenous siRNAs (endo-siRNAs), 21 nucleotides in length, that correspond to transposons and heterochromatic sequences in the somatic cells of Drosophila melanogaster. We also detected endo-siRNAs complementary to messenger RNAs (mRNAs); these siRNAs disproportionately mapped to the complementary regions of overlapping mRNAs predicted to form double-stranded RNA in vivo. Normal accumulation of somatic endo-siRNAs requires the siRNA-generating ribonuclease Dicer-2 and the RNAi effector protein Argonaute2 (Ago2). We propose that endo-siRNAs generated by the fly RNAi pathway silence selfish genetic elements in the soma, much as Piwi-interacting RNAs do in the germ line. 相似文献
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MicroRNA-directed cleavage of HOXB8 mRNA 总被引：1，自引：0，他引：1
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MicroRNA expression in zebrafish embryonic development 总被引：5，自引：0，他引：5
Wienholds E Kloosterman WP Miska E Alvarez-Saavedra E Berezikov E de Bruijn E Horvitz HR Kauppinen S Plasterk RH 《Science (New York, N.Y.)》2005,309(5732):310-311
MicroRNAs (miRNAs) are small noncoding RNAs, about 21 nucleotides in length, that can regulate gene expression by base-pairing to partially complementary mRNAs. Regulation by miRNAs can play essential roles in embryonic development. We determined the temporal and spatial expression patterns of 115 conserved vertebrate miRNAs in zebrafish embryos by microarrays and by in situ hybridizations, using locked-nucleic acid-modified oligonucleotide probes. Most miRNAs were expressed in a highly tissue-specific manner during segmentation and later stages, but not early in development, which suggests that their role is not in tissue fate establishment but in differentiation or maintenance of tissue identity. 相似文献
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【目的】蜜蜂球囊菌(Ascosphaera apis,球囊菌)专性侵染蜜蜂幼虫而导致白垩病。本研究旨在通过small RNA-seq（sRNA-seq）技术和生物信息学方法对球囊菌纯化菌丝（AaM）和纯化孢子（AaS）进行深度测序和比较分析,明确球囊菌菌丝miRNA和孢子miRNA的数量、结构和表达谱差异,并揭示菌丝和孢子共有miRNA、特有miRNA和差异表达miRNA（differentially expressed miRNA,DEmiRNA）及其靶mRNA与球囊菌菌丝和孢子生长、发育和病原致病性的潜在关系。【方法】实验室条件下获得纯培养的球囊菌,利用sRNA-seq技术对AaM和AaS分别进行测序,通过对原始读段（raw reads）进行过滤和质控获得有效标签序列（clean tags）。通过Venn分析筛选菌丝和孢子共有miRNA和特有miRNA。根据P≤0.05且|log2 fold change|≥1的标准筛选AaM vs AaS的DEmiRNA。对上述共有miRNA、特有miRNA和DEmiRNA的靶mRNA进行预测,并对靶mRNA进行GO及KEGG数据库注释。根据靶向结合关系构建DEmiRNA和靶mRNA的调控网络。利用RT-qPCR验证测序数据的可靠性。【结果】AaM和AaS中分别得到12 982 320和12 708 832条raw reads,经过滤和质控分别得到10 800 101和9 888 848条clean tags。AaM中miRNA的长度介于18—26 nt,AaS中miRNA的长度介于18—24 nt,分布miRNA数量最多的长度均为18 nt,AaM和AaS中首位碱基为U的miRNA数量最多。AaM和AaS中表达量最高的miRNA均为miR6478-x、miR10516-x和miR482-x。菌丝和孢子共有miRNA靶向结合5 946个mRNA,二者特有miRNA分别靶向结合6 141和6 346个mRNA。共有miRNA的靶mRNA主要参与代谢进程、细胞进程和催化活性等42个功能条目,以及翻译、碳水化合物代谢和能量代谢等120条通路。AaM vs AaS比较组包含93个DEmiRNA,可靶向结合6 090个mRNA,这些靶mRNA可注释到38个功能条目和120条通路。DEmiRNA与靶mRNA之间形成较为复杂的调控网络,miR-4968-y位于调控网络的中心且能够靶向结合多达118个mRNA。RT-qPCR结果显示5个DEmiRNA的表达趋势与测序数据一致,证实了本研究中测序数据的可靠性。【结论】球囊菌菌丝和孢子中的miRNA具有类似的结构特征,但表达谱表现出明显差异;菌丝和孢子可能通过特异性表达和差异表达部分miRNA对其生长、发育和生殖进行调控。 相似文献
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Farh KK Grimson A Jan C Lewis BP Johnston WK Lim LP Burge CB Bartel DP 《Science (New York, N.Y.)》2005,310(5755):1817-1821
Thousands of mammalian messenger RNAs are under selective pressure to maintain 7-nucleotide sites matching microRNAs (miRNAs). We found that these conserved targets are often highly expressed at developmental stages before miRNA expression and that their levels tend to fall as the miRNA that targets them begins to accumulate. Nonconserved sites, which outnumber the conserved sites 10 to 1, also mediate repression. As a consequence, genes preferentially expressed at the same time and place as a miRNA have evolved to selectively avoid sites matching the miRNA. This phenomenon of selective avoidance extends to thousands of genes and enables spatial and temporal specificities of miRNAs to be revealed by finding tissues and developmental stages in which messages with corresponding sites are expressed at lower levels. 相似文献
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【目的】东方蜜蜂微孢子虫（Nosema ceranae）感染意大利蜜蜂（Apis mellifera ligustica,简称意蜂）导致蜜蜂微孢子虫病。本研究结合前期已获得的miRNA和mRNA组学数据,通过生物信息学方法对意蜂工蜂中肠的差异表达miRNA（differentially expressed miRNA,DEmiRNA）靶向结合的东方蜜蜂微孢子虫的mRNA和差异表达mRNA（DEmRNA）进行预测、数据库注释和调控网络分析,以期在组学水平解析miRNA介导意蜂工蜂对东方蜜蜂微孢子虫的跨界调控机制。【方法】通过比较东方蜜蜂微孢子虫侵染7 d和10 d的意蜂工蜂中肠（AmT1、AmT2）和未受侵染的工蜂中肠（AmCK1、AmCK2）的miRNA组学数据筛选出宿主的显著性DEmiRNA,通过比较侵染意蜂工蜂中肠的东方蜜蜂微孢子虫（NcT1、NcT2）和东方蜜蜂微孢子虫纯净孢子（NcCK）的mRNA数据筛选出病原的DEmRNA。利用TargetFinder软件预测宿主显著性DEmiRNA靶向结合的病原mRNA和DEmRNA。利用相关生物信息学工具对上述靶DEmRNA进行GO和KEGG数据库注释。结合前期研究结果筛选出孢壁蛋白、极管蛋白、蓖麻毒素B凝集素、ABC转运蛋白、ATP/ADP移位酶和糖酵解/糖异生途径等毒力因子和能量代谢通路相关的病原DEmRNA及与其存在靶向结合关系的宿主显著性DEmiRNA,并构建和分析二者的调控网络。【结果】AmCK1 vs AmT1比较组中宿主的48条显著上调miRNA和36条显著下调miRNA分别靶向病原的1 345和1 046条mRNA;进一步分析发现,宿主的47条显著上调miRNA和34条显著下调miRNA可分别靶向NcCK vs NcT1比较组中病原的584条显著下调mRNA和265条显著上调mRNA,它们可分别注释到19和22个功能条目以及66和64条通路。AmCK2 vs AmT2比较组中宿主的56条显著上调miRNA和51条显著下调miRNA分别靶向病原的1 260和1 317条mRNA;进一步分析发现,宿主的52条显著上调miRNA和49条显著下调miRNA可分别靶向NcCK vs NcT2比较组中病原的587条显著下调mRNA和336条显著上调mRNA,它们可分别注释到20和23个功能条目以及64和65条通路。AmCK1 vs AmT1和AmCK2 vs AmT2比较组的8条共同显著上调miRNA和1条共同显著下调miRNA分别靶向NcCK vs NcT1和NcCK vs NcT2比较组中的144条共同显著下调和10条共同显著上调mRNA,可分别注释到18和13个功能条目以及38和7条通路。此外,AmCK1 vs AmT1和AmCK2 vs AmT2比较组中宿主的显著上调miRNA可靶向结合NcCK vs NcT1和NcCK vs NcT2比较组中与RNAi途径,孢壁蛋白和蓖麻毒素B凝集素等毒力因子,糖酵解/糖异生途径以及MAPK信号通路相关的病原下调表达mRNA。【结论】在东方蜜蜂微孢子虫的侵染过程中,意蜂工蜂中肠的DEmiRNA与病原的DEmRNA之间存在复杂的靶向结合关系以及潜在的跨界调控关系;宿主的DEmiRNA可能通过抑制或降解病原的RNAi途径、毒力因子、糖酵解/糖异生通路、ATP/ADP移位酶、ABC转运蛋白及MAPK信号通路相关靶DEmRNA影响病原的侵染和增殖。 相似文献
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Ribosome profiling shows that miR-430 reduces translation before causing mRNA decay in zebrafish 总被引：1，自引：0，他引：1
MicroRNAs regulate gene expression through deadenylation, repression, and messenger RNA (mRNA) decay. However, the contribution of each mechanism in non-steady-state situations remains unclear. We monitored the impact of miR-430 on ribosome occupancy of endogenous mRNAs in wild-type and dicer mutant zebrafish embryos and found that miR-430 reduces the number of ribosomes on target mRNAs before causing mRNA decay. Translational repression occurs before complete deadenylation, and disrupting deadenylation with use of an internal polyadenylate tail did not block target repression. Lastly, we observed that ribosome density along the length of the message remains constant, suggesting that translational repression occurs by reducing the rate of initiation rather than affecting elongation or causing ribosomal drop-off. These results show that miR-430 regulates translation initiation before inducing mRNA decay during zebrafish 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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Target protectors reveal dampening and balancing of Nodal agonist and antagonist by miR-430 总被引：2，自引：0，他引：2
MicroRNAs (miRNAs) repress hundreds of target messenger RNAs (mRNAs), but the physiological roles of specific miRNA-mRNA interactions remain largely elusive. We report that zebrafish microRNA-430 (miR-430) dampens and balances the expression of the transforming growth factor-beta (TGF-beta) Nodal agonist squint and the TGF-beta Nodal antagonist lefty. To disrupt the interaction of specific miRNA-mRNA pairs, we developed target protector morpholinos complementary to miRNA binding sites in target mRNAs. Protection of squint or lefty mRNAs from miR-430 resulted in enhanced or reduced Nodal signaling, respectively. Simultaneous protection of squint and lefty or absence of miR-430 caused an imbalance and reduction in Nodal signaling. These findings establish an approach to analyze the in vivo roles of specific miRNA-mRNA pairs and reveal a requirement for miRNAs in dampening and balancing agonist/antagonist pairs. 相似文献