RNA干扰机制及其主要蛋白因子研究进展

RNA干扰(RNA interference, RNAi)是由双链RNA(double stranded RNA, dsRNA)分子介导的、在mRNA水平上关闭相应序列基因表达、使其沉默的过程。RNAi作为一种古老而保守的基因沉默机制,广泛存在于真核生物体内,在细胞的发育调控、抗病毒防御、修复遗传损伤、调节正常的基因等生命过程中起着重要的作用。RNAi机制可以分为3个阶段：启动阶段、效应阶段及扩增阶段。RNAi干扰相关的主要蛋白因子有Dicer酶、Argonaute(AGO) 蛋白家族和RNA依赖的RNA聚合酶(RNA\|dependent RNA polymerase, RdRP)。文章对RNAi机制及其相关主要蛋白因子进行简要综述。     

RNAi技术及其应用

RNAi主要通过双链RNA(dsRNA)被核酸酶切割成21~23 nt的干涉性小的RNA,即siRNA,由siRNA介导识别并靶向切割同源性靶mRNA分子而实现。目前RNAi技术在基因功能和基因治疗等方面的研究有了广泛的应用,RNAi技术有望成为后基因组时代基因功能分析的有力工具。     

RNAi技术在植物功能基因组学中的研究进展

文章主要综述了RNA干涉(RNAi)技术在植物功能基因组学中的研究策略及研究现状,包括RNA干涉的作用机制及技术特征,引发植物RNAi机制的转基因RNAi技术以及病毒介导的基因沉默技术。转基因RNAi技术方面,包括载体结构的优化策略、高通量载体的构建方法以及该技术的优缺点。病毒介导的基因沉默技术方面包括病毒载体及宿主种类,病毒感染方法,试验对照的建立、环境因素的影响以及该技术的优缺点。     

dsRNA引发的基因沉默

双链RNA(double-stranded RNA，dsRNA)导入细胞后引起细胞内特定的信使核糖核酸(messenger RNA，mRNAs)降解，从而导致基因沉默，并使生物体产生相应的功能缺陷型，这种由dsRNA介导的基因沉默称为RNA干涉(RNAi)，RNAi普遍存在于植物、动物、真菌中，它的发现改变了人们对细胞如何保护其基因组的理解，并发展了研究基因功能的新战略．对RNAi的发现历史、作用特点、作用机制以及应用前景进行了简述．     

RNA干涉技术及其在哺乳动物中的应用进展

RNA干涉(RNA interference,RNAi)作为一种有效的用于转录后基因沉默,从而抑制特定基因表达的技术,近年来在哺乳动物细胞中的研究已取得了长足发展,且在基因功能以及疾病治疗的研究中有着广阔的应用前景。研究表明,哺乳动物细胞中的RNAi作用方式与植物有所不同,笔者对哺乳动物RNAi技术的发展、作用机制及其在基因功能、基因治疗、转基因动物研究、药物开发等方面的应用做了综述。     

RNA干涉及其应用

在各种各样的真核生物当中,双链RNA(dsRNA)促使了有效的同源mRNA分子降解,这个过程被称为RNA干扰(RNAi)。RNAi现象通过调控RNA抑制基因表达,它在植物、动物、真菌中广泛存在,被认为是一种抑制病毒性复制和转座子活动的抗御机制,而在此过程中,侵染型病毒为了能够不被这种机制干扰抑制,继续在寄主体内生存、繁殖,则产生了一种反抗御机制———即产生抑制蛋白来对付转录后基因沉默(PTGS)。对RNAi以及RNAi抑制物的作用机制、抑制物类型、特点及相关应用方面作了比较详尽的综述。dsRNA介导的PTGS将是分子生物学领域的研究热点之一,在研究基因功能,基因治疗,抗病毒基因工程,解剖和调控次生代谢途径等方面有着广泛的应用前景。     

RNA干扰技术应用的研究进展

综述了RNA干扰(RNAi)的作用机理、介导载体、在哺乳动物中的应用现状和前景。     

RNA干扰研究现状

RNA干扰(RNAi)是指生物体内利用双链RNA(dsRNA)诱导同源靶基因的mRNA特异性降解,从而导致转录后基因沉默的现象。其在抵抗病毒感染、抑制转座子活动、调控内源性基因表达等方面发挥重要作用。RNAi以其高特异性、高效性等显著优势将成为研究基因功能的全新手段。简要概括RNAi作用机制和siRNA技术的原理,同时也讨论了RNAi技术在其他领域,如在基因信号通路研究、高通量研究基因功能、基因治疗如肿瘤研究和疾病治疗等方面的应用。     

siRNA和miRNA的研究进展

RNAi(RNA interference)即RNA干涉,是由外源或内源性的双链RNA(double starand RNA,dsRNA)导入细胞而引起的与dsRNA同源的mRNA降解,进而抑制相应基因表达,可以抑制诸多真核基因的表达s。iRNA(small interferance RNA,siRNA)即小干扰性RNA,是RNA干扰的引发物,不同的siRNA可以引导不同水平的RNAi。非编码RNA中的微小RNA(micro RNA,miRNA),能够识别特定的目标mRNA,通过与mRNAs3’非翻译区结合,影响蛋白翻译水平。miRNA和siRNA在生成机制、作用途径等方面关系密切,既区别又相互联系,小分子RNA的研究将是今后分子生物学的研究热点之一。     

RNA interference in Colorado potato beetle(Leptinotarsa decemlineata): A potential strategy for pest control

Colorado potato beetle(CPB), Leptinotarsa decemlineata, is a notorious destructive pest that mainly feeds on the leaves of potato and several other solanaceous plants. CPB is widely recognized for its adaptation to a remarkable variety of host plants and diverse climates, and its high resistance to insecticides and Bacillus thuringiensis toxins. RNA interference(RNAi) is a sequence-specific, endogenous gene silencing mechanism evoked by small RNA molecules that is used as a robust tool for virus and pest control. RNAi has been extensively tested for CPB management by employing various target genes and delivery methods. This article reviews the screening of RNAi target genes, efficient RNAi delivery systems, and factors affecting RNAi efficiency in CPB, which may help understand the mechanisms of RNAi and its application in CPB control strategy.     

A microRNA in a multiple-turnover RNAi enzyme complex

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.     

R2D2, a bridge between the initiation and effector steps of the Drosophila RNAi pathway

The RNA interference (RNAi) pathway is initiated by processing long double-stranded RNA into small interfering RNA (siRNA). The siRNA-generating enzyme was purified from Drosophila S2cells and consists of two stoichiometric subunits: Dicer-2(DCR-2) and a previously unknown protein that we named R2D2. R2D2 is homologous to the Caenorhabditis elegans RNAi protein RDE-4. Association with R2D2 does not affect the enzymatic activity of DCR-2. Rather, the DCR-2/R2D2 complex, but not DCR-2 alone, binds to siRNA and enhances sequence-specific messenger RNA degradation mediated by the RNA-initiated silencing complex (RISC). These results indicate that R2D2 bridges the initiation and effector steps of the Drosophila RNAi pathway by facilitating siRNA passage from Dicer to RISC.     

siRNA对鸡胚成纤维细胞中GAPDH基因表达的抑制作用

RNA干扰(RNA interference,RNAi)是通过短双链RNA(small interference RNA,siRNA)介导的特异性抑制相应基因表达的新技术。作为研究基因功能的有效手段,该技术已在线虫、果蝇、斑马鱼和鼠等动物中进行了应用。本研究利用体外转录合成的短双链干扰RNA(siRNA),针对鸡的管家基因3-磷酸甘油醛脱氢酶基因(glyceraldehyde-3-phosphate dehydrogenase,GAPDH),在鸡胚成纤维细胞中对其表达进行干扰。结果显示siGAPDH能有效阻断GAPDH基因在鸡胚成纤维细胞中的表达,而不相关的siRNA则对该基因的表达没有影响,证明在鸡细胞中也存在RNA干扰现象,为利用RNAi技术对鸡的基因功能研究奠定了一定基础。     

The Piwi-piRNA pathway provides an adaptive defense in the transposon arms race

Increasingly complex networks of small RNAs act through RNA-interference (RNAi) pathways to regulate gene expression, to mediate antiviral responses, to organize chromosomal domains, and to restrain the spread of selfish genetic elements. Historically, RNAi has been defined as a response to double-stranded RNA. However, some small RNA species may not arise from double-stranded RNA precursors. Yet, like microRNAs and small interfering RNAs, such species guide Argonaute proteins to silencing targets through complementary base-pairing. Silencing can be achieved by corecruitment of accessory factors or through the activity of Argonaute itself, which often has endonucleolytic activity. As a specific and adaptive regulatory system, RNAi is used throughout eukarya, which indicates a long evolutionary history. A likely function of RNAi throughout that history is to protect the genome from both pathogenic and parasitic invaders.     

RNA干涉技术研究进展

RNA干涉是由双链RNA引起的转录后基因沉默机制.RNAi作为一门新的基因沉默技术,具有序列特异性和高效性等许多优点,在基因功能研究、疾病治疗、药物开发等方面具有广泛的应用.综述RNAi现象的发现、发生机制及其应用,并展望未来的研究.