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siRNA检测芯片 :RNAi基因沉默新技术Genetix公司研制成功一系列适合检测RNA干扰研究中siRNA分子干扰效果的基因芯片产品。在即将于 2 0 0 4年 10月召开的RNAi欧洲会议上 ,Genetix将会介绍他们的QAr rayMini生物芯片和可选择蓝色激光的aQuire基因芯片扫描仪 ,这一组合是进行RNAi优化实验的完美配套产品。RNAi已经发展成一种强大的分子生物学研究工具 ,用于沉默细胞中的目标基因。研究人员能够使用各种不同的技术将双链siRNA分子 (一般长度为 2 0 2 5个核苷酸 )引入到哺乳动物细胞中。一旦进入细胞 ,这些分子就会与互补的目标mR…     

RNA干扰技术在哺乳动物中的应用

RNA干扰(RNAi)是生物界普遍存在的一种抵御外来基因和病毒感染的进化保守机制.RNAi是由双链RNA触发的转录后基因沉默机制,具有序列特异性,在哺乳动物细胞中,RNAi由21～23个核苷酸组成的双链RNA引发.小干扰RNA(siRNA)可以在体外合成或通过表达载体在哺乳动物细胞内合成.由于RNAi技术具有快速、简单和特异性强等特点,在基因功能研究、抗病毒治疗和抗肿瘤治疗等方面有广泛的应用前景.     

RNAi的触发机制及其在哺乳动物基因功能分析中的应用

RNAi是外源和内源性dsRNA在细胞内诱导具有同源序列的基因瞬时或稳定表达抑制的现象,是一种在实验室中进行基因功能分析的强大工具.本文将对RNAi的触发机制、哺乳动物细胞内触发RNAi的3种触发子(siRNA、shRNA、shRNAmir)及RNAi在基因功能分析中的研究进展作一综述.     

RNAi在药物研究中的应用

RNA干扰是双链RNA分子在mRNA水平上诱发的序列特异性的转录后基因表达沉默。在哺乳动物细胞里,RNAi可以由21-25个核苷酸长度的小干扰RNA（siRNA）触发,在后基因组时代的基因功能研究和药物开发中具有广阔的应用前景。现针对近年RNAi在药物研究中的应用包括应用RNAi发现新药靶、辅助确认药靶、RNAi药物、RNAi与耐药性等方面作一综述。     

RNAi及其抑制口蹄疫病毒复制的研究进展

RNA干扰(RNA interference,RNAi)是指由双链RNA(double strand RNA,dsRNA)介导的序列特异的RNA降解过程。已经证明,在植物和昆虫细胞中RNAi是其主要的抗病毒免疫机制,至今为止几乎没有发现在病毒感染哺乳动物细胞过程中诱发有效的抗病毒RNAi反应。因此,人们希望能够利用人工方法在哺乳动物细胞中建立有效的抗病毒RNAi防御策略。迄今为止,对多种哺乳动物病毒的研究结果令人振奋。主要围绕RNAi的分子基础、基本策略及其在抑制口蹄疫病毒复制中的研究现状作了综述。     

针对SARS冠状病毒重要蛋白的siRNA设计(英)

RNA干涉(RNA interference, RNAi)是一种特异性地导致转录后基因沉默的现象,在哺乳动物细胞中小分子干扰RNA双链体(small interfering RNA duplexes, siRNA duplexes)可以有效地诱导RNAi现象,为一些疾病的治疗开辟了新的途径.针对SARS冠状病毒(SARS coronavirus, SARS-CoV)中编码5个主要蛋白质的基因,用生物信息学的方法设计了348条候选siRNA靶标.在理论上,相应的siRNA双链体能特异地抑制SARS-CoV靶基因的表达,同时不会影响人体细胞基因的正常表达,这为进一步siRNA类药物的实验研究提供了理论基础.     

RNA干扰及抗病毒研究进展

RNAi是一种高度特异化的mRNA降解过程,能在哺乳动物细胞中诱导特异的基因沉默。这一发现为人类某些疾病的治疗研究开辟了新的途径。随着研究的不断深入,RNA i在抗病毒研究中受到越来越多的关注。本文拟就RNA i的机制、siRNA靶系列的选择及制备和抗病毒研究现状作一综述。     

针对SARS冠状病毒重要蛋白的siRNA设计(英文)

NA干涉 (RNAinterference ,RNAi)是一种特异性地导致转录后基因沉默的现象 ,在哺乳动物细胞中小分子干扰RNA双链体 (smallinterferingRNAduplexes ,siRNAduplexes)可以有效地诱导RNAi现象 ,为一些疾病的治疗开辟了新的途径 .针对SARS冠状病毒 (SARScoronavirus ,SARS CoV)中编码 5个主要蛋白质的基因 ,用生物信息学的方法设计了3 48条候选siRNA靶标 .在理论上 ,相应的siRNA双链体能特异地抑制SARS CoV靶基因的表达 ,同时不会影响人体细胞基因的正常表达 ,这为进一步siRNA类药物的实验研究提供了理论基础     

RNA干涉与干细胞

RNA干涉(RNAi)现象普遍存在于生物体细胞中,在理论上已清楚其分子机制,为干细胞研究提供了新的方法。现从RNAi的分子机制、干细胞中的RNAi现象、研究干细胞RNAi效应的方法以及小分子干涉RNA(siRNA)干涉干细胞特异功能基因的检测方法等方面进行了综述。表明应用RNAi技术研究基因功能和干细胞维持及定向分化的调控具有广阔的发展前景。     

RNAi,生物体内的基因免疫

RNAi,是广泛存在于植物、线虫、果蝇、真菌和动物中的1种抗病毒机制,如同脊椎动物的免疫系统,能特异地抵抗病毒感染。本文阐述了RNAi机制及其在哺乳动物细胞中的研究,进一步说明RNAi在基因水平上对机体的保护作用。     

Structural diversity repertoire of gene silencing small interfering RNAs

Since the discovery of double-stranded (ds) RNA-mediated RNA interference (RNAi) phenomenon in Caenorhabditis elegans, specific gene silencing based upon RNAi mechanism has become a novel biomedical tool that has extended our understanding of cell biology and opened the door to an innovative class of therapeutic agents. To silence genes in mammalian cells, short dsRNA referred to as small interfering RNA (siRNA) is used as an RNAi trigger to avoid nonspecific interferon responses induced by long dsRNAs. An early structure-activity relationship study performed in Drosophila melanogaster embryonic extract suggested the existence of strict siRNA structural design rules to achieve optimal gene silencing. These rules include the presence of a 3' overhang, a fixed duplex length, and structural symmetry, which defined the structure of a classical siRNA. However, several recent studies performed in mammalian cells have hinted that the gene silencing siRNA structure could be much more flexible than that originally proposed. Moreover, many of the nonclassical siRNA structural variants reported improved features over the classical siRNAs, including increased potency, reduced nonspecific responses, and enhanced cellular delivery. In this review, we summarize the recent progress in the development of gene silencing siRNA structural variants and discuss these in light of the flexibility of the RNAi machinery in mammalian cells.     

Control of siRNA expression using the Cre-loxP recombination system

Gene silencing mediated by RNA interference (RNAi) was first discovered in Caenorhabditis elegans, and was subsequently recognized in various other organisms. In mammalian cells, RNAi can be induced by small interfering RNAs (siRNAs). In earlier studies, our group developed a vector-based system for expression of siRNA under control of a polymerase III promoter, the U6 promoter, which can induce RNAi in living cells. We here describe a system for controlling the U6 promoter-driven expression of siRNA using the Cre-loxP recombination system. We constructed a 'Cre-On' siRNA expression vector which could be switched on upon excision catalyzed by Cre recombinase, which was delivered to cells directly from the medium as a fusion protein. An examination of the effectiveness of RNAi against a reporter gene revealed that addition of TAT-NLS-Cre (where NLS is a nuclear localization signal and TAT is a peptide of 11 amino acids derived from HIV) to the medium resulted in plasmid recombination, generation of siRNA and suppression of reporter activity. This system should allow us to induce RNAi in a spatially, temporally, cell type-specifically or tissue-specifically controlled manner and potentiate the improved application of RNAi in both an experimental and a therapeutic context.     

A simple strategy for generation of gene knockdown constructs with convergent H1 and U6 promoters

RNA interference (RNAi) is a powerful tool for functional genetic studies in model organisms and mammalian cells. To facilitate rapid construction of gene knockdown constructs and RNAi libraries for known genes of mammalian cells, a new and simple strategy to produce small interfering RNA (siRNA) expression vectors with two opposing polymerase III promoters was developed. The design involved a one-step PCR amplification and single cloning procedure to construct a dual promoter siRNA expression vector. The forward primer is identical for all PCR reactions, only a single reverse primer that contains the siRNA targeting sequence has to be synthesized in the construction of each individual vector. This single primer design is cost-effective and it reduces the risk of sequence errors during synthesis of long oligos. Sense and antisense strands of siRNA duplexes were transcribed from the same template and this eliminated the need to synthesize long hairpin-forming oligonucleotides. Our study demonstrated that this vector design could mediate potent inhibition of expression of both exogenous and endogenous genes in mammalian cells.     

Control of siRNA expression using the Cre–loxP recombination system

Gene silencing mediated by RNA interference (RNAi) was first discovered in Caenorhabditis elegans, and was subsequently recognized in various other organisms. In mammalian cells, RNAi can be induced by small interfering RNAs (siRNAs). In earlier studies, our group developed a vector-based system for expression of siRNA under control of a polymerase III promoter, the U6 promoter, which can induce RNAi in living cells. We here describe a system for controlling the U6 promoter-driven expression of siRNA using the Cre–loxP recombination system. We constructed a ‘Cre-On’ siRNA expression vector which could be switched on upon excision catalyzed by Cre recombinase, which was delivered to cells directly from the medium as a fusion protein. An examination of the effectiveness of RNAi against a reporter gene revealed that addition of TAT-NLS-Cre (where NLS is a nuclear localization signal and TAT is a peptide of 11 amino acids derived from HIV) to the medium resulted in plasmid recombination, generation of siRNA and suppression of reporter activity. This system should allow us to induce RNAi in a spatially, temporally, cell type-specifically or tissue-specifically controlled manner and potentiate the improved application of RNAi in both an experimental and a therapeutic context.     

Focusing on RISC assembly in mammalian cells

RISC (RNA-induced silencing complex) is a central protein complex in RNAi, into which a siRNA strand is assembled to become effective in gene silencing. By using an in vitro RNAi reaction based on Drosophila embryo extract, an asymmetric model was recently proposed for RISC assembly of siRNA strands, suggesting that the strand that is more loosely paired at its 5′ end is selectively assembled into RISC and results in target gene silencing. However, in the present study, we were unable to establish such a correlation in cell-based RNAi assays, as well as in large-scale RNAi data analyses. This suggests that the thermodynamic stability of siRNA is not a major determinant of gene silencing in mammalian cells. Further studies on fork siRNAs showed that mismatch at the 5′ end of the siRNA sense strand decreased RISC assembly of the antisense strand, but surprisingly did not increase RISC assembly of the sense strand. More interestingly, measurements of melting temperature showed that the terminal stability of fork siRNAs correlated with the positions of the mismatches, but not gene silencing efficacy. In summary, our data demonstrate that there is no definite correlation between siRNA stability and gene silencing in mammalian cells, which suggests that instead of thermodynamic stability, other features of the siRNA duplex contribute to RISC assembly in RNAi.