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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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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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MicroRNAs(miRNAs) are small noncoding RNAs of 18–25 nucleotides(nt) in length that represent key regulators of many normal cellular functions through the inhibition of mRNA translation and mRNA degradation. To date, over 2 500 mature miRNAs have been identified in plants, animals and several types of viruses. Influenza A virus(IAV), which is a negativesense, single-stranded RNA virus, does not encode viral miRNA. However, IAV infection can alter the expression of host miRNAs, either in cell culture or in host. In turn, host miRNAs regulate IAV life cycle through directly binding to IAV genome or indirectly targeting host factors associated with viral replication. In this review, we briefly summarized the role and significance of miRNA in relation to IAV pathogenesis. Understanding the role of cellular miRNAs during viral infection may be beneficial to the identification of novel therapeutic strategies to block IAV replication. 相似文献
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Pillai RS Bhattacharyya SN Artus CG Zoller T Cougot N Basyuk E Bertrand E Filipowicz W 《Science (New York, N.Y.)》2005,309(5740):1573-1576
MicroRNAs (miRNAs) are approximately 21-nucleotide-long RNA molecules regulating gene expression in multicellular eukaryotes. In metazoa, miRNAs act by imperfectly base-pairing with the 3' untranslated region of target messenger RNAs (mRNAs) and repressing protein accumulation by an unknown mechanism. We demonstrate that endogenous let-7 microribonucleoproteins (miRNPs) or the tethering of Argonaute (Ago) proteins to reporter mRNAs in human cells inhibit translation initiation. M(7)G-cap-independent translation is not subject to repression, suggesting that miRNPs interfere with recognition of the cap. Repressed mRNAs, Ago proteins, and miRNAs were all found to accumulate in processing bodies. We propose that localization of mRNAs to these structures is a consequence of translational repression. 相似文献
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植物miRNA的生物学特性及在环境胁迫中的作用 总被引：2，自引：0，他引：2
MicroRNA(miRNA)是一类在生物体内普遍存在的非编码、长度约为21 nt的小RNA分子,一般由内源基因编码,RNA聚合酶Ⅱ转录后,经过Dicer-Like酶等一系列的蛋白复合物将pre-miRNA(precursor miRNA)剪切成成熟miRNA,在转录及转录后水平介导靶mRNA转录沉默、降解或翻译抑制来调控基因的表达,是真核细胞基因表达的重要调控因子。第一个miRNA是在秀丽隐杆线虫(C.elegans)中发现的lin-4,与lin-14 mRNA 3′UTR的碱基序列部分互补,降解lin-14,从而抑制lin-14的表达。lin-4对靶基因lin-14的调控与线虫的生长发育密切相关。而第一个发现的植物miRNA是拟南芥mi R171,它靶向剪切编码基因Scarecrow-Like(SCL)家族的mRNA,调控其基因的表达,进而影响植物的生长发育。植物部分miRNA,如mi R156—mi R408在各植物物种中相对保守,而mi R408以后的miRNA具有物种特异性。植物在生长过程中会遭遇诸多不可预知(如同盐碱、干旱、重金属以及害虫和病原菌的侵扰等)的环境胁迫。固着生长的特性使得植物不能像动物那样通过移动来避免不利环境的影响,因此,需要自身特殊机制来应对这些环境胁迫。植物在长期逆境中已进化出极为精细复杂的生理和分子机制。miRNA与它作用的靶基因是响应环境胁迫的主要调控因子。miRNA参与了植物的生长发育、信号转导、蛋白质降解、营养胁迫、抗病原菌的入侵以及适应高盐和干旱等逆境胁迫过程,对于调节内源抗性基因表达具有一定意义。目前通过高通量测序、实时定量PCR检测和转基因等技术已经发现了很多与环境胁迫相关的miRNA,它们在逆境胁迫下的表达呈现显著差异性;miRNA的过表达植株经逆境胁迫处理可能表现出一定的抗逆或敏感性。同一家族的miRNA不同成员在响应环境胁迫时具有物种特异性。新疆地区是典型的大陆性干旱气候,降水量少,盐碱荒漠化地区多。在这样严酷的环境中顽强生存着许多盐生旱生类植物,这些植物的miRNA如何在逆境中发挥调控作用,依然需要更深入的探索。本文主要综述了现阶段植物miRNA生物合成、与靶基因作用方式、生物功能以及不同环境胁迫下对miRNA和作用的靶基因影响等方面的研究进展,以便更好地利用miRNA依据的生物技术开展研究和应用转化。 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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蛋白质翻译起始因子的作用与调控 总被引：2，自引：0，他引：2
蛋白质翻译起始因子是一类在真核细胞中蛋白质翻译所必需的、保证正确的mRNA－核糖体复合物形成的蛋白质,已知的起始因子共有12种,在真核细胞翻译起始阶段有重要作用。蛋白质合成的调节主要通过翻译起始因子的磷酸化进行。真核细胞蛋白质翻译最重要的调节位点是翻译起始因子eIF 2和eIF 4。本文主要综述了近年来关于蛋白质翻译起始因子的作用及调控的最新研究进展 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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miRNA can regulate development and milk yield of the mammary gland through epigenetic mechanism.miRNA can directly and indirectly modulate the activity of the epigenetic machinery,target genes through post-inhibition of translation initiation,mediate miRNA decay,target genes and inhibit the positive regulation,regulate tone modification,and regulate DNA methylation of target genes.Here we reviewed the role of miRNAs in mammary gland development and lactation.Researching miRNA in mammary gland development and lactation process,and understanding the response of the epigenetic mechanisms to external stimuli will be an important necessity to devise new technologies for maximizing their activity and milk production in the dairy cow. 相似文献
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Eukaryotic cells contain nontranslating messenger RNA concentrated in P-bodies, which are sites where the mRNA can be decapped and degraded. We present evidence that mRNA molecules within yeast P-bodies can also return to translation. First, inhibiting delivery of new mRNAs to P-bodies leads to their disassembly independent of mRNA decay. Second, P-bodies decline in a translation initiation-dependent manner during stress recovery. Third, reporter mRNAs concentrate in P-bodies when translation initiation is blocked and resume translation and exit P-bodies when translation is restored. Fourth, stationary phase yeast have large P-bodies containing mRNAs that reenter translation when growth resumes. The reciprocal movement of mRNAs between polysomes and P-bodies is likely to be important in the control of mRNA translation and degradation. Moreover, the presence of related proteins in P-bodies and maternal mRNA storage granules suggests this mechanism is widely adapted for mRNA storage. 相似文献
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【目的】 回顾与总结番茄MicroRNA(miRNA)调控其生长发育及逆境响应的研究现状及进展,为番茄育种的应用提供理论和科学依据。【方法】 查阅国内外相关文献,汇总并对比分析文献数据。【结果】 miRNA是一类广泛存在于植物体内,位于基因组非编码区长约21～25个核苷酸的内源性非编码小分子RNA。其通过定向降解靶基因mRNA和抑制其翻译,对靶基因表达在转录后水平起调控作用。高通量测序的出现有助于植物miRNAs的数量呈指数增长,使得miRNAs相关数据库种类及数据量日渐丰富。番茄诸多生物学过程都受到miRNA的调控,包括植株形态、器官发育、生长发育以及响应干旱、盐、温度和生物胁迫等方面。【结论】 miRNAs在番茄生长发育和胁迫应答等方面起重要作用,围绕miRNAs及其靶基因对番茄的调控机制,定向改变番茄果实品质及生长周期。 相似文献
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植物miRNA是广泛分布于植物基因组的长度在22个核苷酸左右的内源性非编码调控RNA,是真核生物基因表达的一类负调控因子,主要通过指导靶基因的切割或降低靶基因的翻译从转录后水平上抑制植物基因表达,在控制植物的发育、开花时序、新陈代谢、应激反应等方面起着重要的作用.已知植物miRNA在转录后水平上抑制基因表达,主要是通过导致mRNA的裂解,对抑制目标转录物的翻译起作用.综述了植物miRNA形成、作用机理、功能和研究方法等方面的研究进展. 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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非编码RNA对哺乳动物精子发生过程的调控 总被引：3，自引：2，他引：1
精子发生始于精原干细胞(spermatogonial stem cells,SSCs),SSCs一部分自我更新,另一部分首先分裂形成Asingle(As)型精原细胞,进而形成Aparied(Apr)型精原细胞和Aaligned(Aal)型精原细胞;随后,Aal型精原细胞再发育为A1-A4型精原细胞、中间型精原细胞以及B型精原细胞;B型精原细胞有丝分裂可形成初级精母细胞,经历前细线期、细线期、偶线期、粗线期,再经减数分裂形成次级精母细胞;当圆形精子细胞形成之后,则经细胞核浓缩等过程形成晚期的细长型成熟精子,随之最终变形成为精子。这一复杂的生理过程需要相关基因的适时表达,并受到转录和转录后水平的调控。研究表明,多种类型的非编码RNA(nc RNAs)在精子发生过程中发挥着重要作用。nc RNAs包括微小RNAs(mi RNAs)、与Piwi蛋白相互作用的RNAs(pi RNAs)、长链非编码RNAs(lnc RNAs)、环状RNAs(circ RNAs)以及内源性小干扰RNAs(endo-si RNAs)等。这些nc RNAs的表达具有细胞组织特异性和发育阶段特异性,可从时间和空间上精确调控精子发生的整个过程。mi RNAs是一类长约21—25 nt的内源性非编码单链RNA分子,广泛存在于各种生物中,其形成至少需要Drosha和Dicer等两种RNA酶的参与,可降解靶m RNA或抑制靶m RNA翻译,对SSCs干性的维持、自我更新和分化的调控以及生殖细胞减数分裂和精子发生过程具有重要的调控作用。此外,精子发生过程中,在生殖细胞不同阶段所表达的基因也可调控mi RNAs的生成加工过程。pi RNAs是2006年发现的一种新的小RNA,长度约24—32nt,其作用与Dicer酶无关,能够与生殖细胞特异性蛋白Piwi蛋白家族成员结合,进而行使生物学功能,其主要表现为:在表观遗传水平和转录后水平沉默转座子、反转座子等基因组移动遗传元件,维持生殖细胞自身基因组稳定性和完整性,调控生殖细胞增殖、减数分裂及精子发生过程。Lnc RNAs是一类长度大于200 nt的nc RNAs,其生成加工过程与m RNA类似,并且与m RNA有着相似的结构。不同来源的lnc RNAs可通过转录前与转录后多种机制进而调控SSCs的干性及分化,并且调控生殖细胞凋亡。有些lnc RNAs还可调控mi RNAs的表达,进而调控精子发生过程。circ RNAs是区别于传统线性RNA的一类新型RNA,在不同物种中具有保守性,在组织及不同发育阶段呈特异性表达。其生成加工方式与其序列相关,同一基因位点可通过选择性环化产生多种circ RNAs进而发挥功能。研究表明,circ RNAs可结合mi RNAs从而调控生精过程。相对于其他nc RNAs,endo-si RNAs的生成加工方式更为简单,并有着与mi RNAs相同的作用方式,在精子发生和雄性生殖中扮演着重要角色。文中结合最新的研究进展,综述了几种nc RNAs的生成及其在精子发生过程中的调控作用,旨在为精子发生过程中nc RNAs的进一步研究提供参考。 相似文献
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Dorrello NV Peschiaroli A Guardavaccaro D Colburn NH Sherman NE Pagano M 《Science (New York, N.Y.)》2006,314(5798):467-471
The tumor suppressor programmed cell death protein 4 (PDCD4) inhibits the translation initiation factor eIF4A, an RNA helicase that catalyzes the unwinding of secondary structure at the 5' untranslated region (5'UTR) of messenger RNAs (mRNAs). In response to mitogens, PDCD4 was rapidly phosphorylated on Ser67 by the protein kinase S6K1 and subsequently degraded via the ubiquitin ligase SCF(betaTRCP). Expression in cultured cells of a stable PDCD4 mutant that is unable to bind betaTRCP inhibited translation of an mRNA with a structured 5'UTR, resulted in smaller cell size, and slowed down cell cycle progression. We propose that regulated degradation of PDCD4 in response to mitogens allows efficient protein synthesis and consequently cell growth. 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