Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RNA Interference”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed2004

[Experimental research of targeting hTERT gene inhibited in hepatocellular carcinoma therapy by RNA interference].

BACKGROUND & OBJECTIVE: RNA interference (RNAi) is a new gene blocking technology that silences target gene at post-transcription level induced by the small interference RNA (siRNA). RNAi has been demonstrated great prospect in gene functional research and gene therapy areas. Nowadays, RNAi has been reported to be used to inhibit the expression of endogenous genes including cyclophilin, GAPDH, p53, and c-myc; and there were some progresses in the therapy of the diseases caused by AIDS and hepatitis viruses with RNAi. However, hTERT gene, which was highly expressed in hepatocellular carcinoma and other malignant neoplasm, has not been researched by RNAi. In present research, we utilized RNAi to inhibit hTERT gene expression in vitro and in vivo, investigated the feasibility and specificity of gene therapy for hepatocellular carcinoma. METHODS: Small interference RNAs homologous to hTERT gene were designed,pTZU6+1-shRNA-hTERT vector was constructed and transfected into hepatocellular carcinoma SMMC-7721 cells and transplanted SMMC-7721 tumor in nude mice to induce RNAi. The changes of hTERT gene expression and tumor cell proliferation in both siRNA treatment groups and control group were determined by flow cytometry, reverse transcription polymerase chain reaction (RT-PCR), immunochemistry in vitro and in vivo. RESULTS: The expression of hTERT had been obviously inhibited by RNAi in vitro. The inhibition rate of cell growth was 37.5% after pTZU6+1-shRNA-hTERT vector was transfected to hepatocellular carcinoma SMMC-7721 cells; the phase of cell cycle indicated the reduction of S phase, while G(1)/G(0) phase increased. The mRNA level of hTERT decreased from 99.4% to 53.1%, its protein expression reduced from 86.3% to 46.6%. The tumor size reduced after treated with pTZU6+1-shRNA-hTERT vector in vivo; hTERT mRNA level decreased from 99.1% to 76.2%, and its protein expression decreased from 87.2% to 61.8% in siRNA treatment group. In contrast, there were no changes in control groups in vitro and in vivo. CONCLUSION: RNAi inhibits the hTERT gene expression and proliferation of hepatocellular carcinoma SMMC-7721 cells with specificity, and is a possible new approach for neoplasm gene therapy.

Animals↗
PubMed2003

Stable gene silencing in human monocytic cell lines using lentiviral-delivered small interference RNA. Silencing of the p110alpha isoform of phosphoinositide 3-kinase reveals differential regulation of adherence induced by 1alpha,25-dihydroxycholecalciferol and bacterial lipopolysaccharide.

Studying mononuclear phagocyte cell biology through genetic manipulation by non-viral transfection methods has been challenging due to the dual problems of low transfection efficiency and the difficulty in obtaining stable transfection. To overcome this problem, we developed a system for mediating RNA interference in monocytic cells. The p110alpha isoform of phosphoinositide 3-kinases (PI3Ks) was silenced using a lentiviral vector expressing short hairpin RNA (shRNA). This resulted in the generation of stable THP-1 and U-937 monocytic cell lines deficient in p110alpha. Notably, p110alpha was silenced without affecting levels of either the other class I(A) PI3K catalytic subunits p110beta and p110delta, or the p85alpha regulatory subunit. The role of p110alpha in mediating cell adherence was examined. Monocyte adherence induced in response to either lipopolysaccharide (LPS) or 1alpha,25-dihydroxycholecalciferol (D(3)) was blocked by the PI3K inhibitor LY294002. However, although adherence induced in response to D(3) was sensitive to silencing of p110alpha, LPS-induced adherence was not. Expression of the monocyte differentiation marker CD11b was also induced by D(3) in a PI3K-dependent manner and gene silencing using shRNA showed that p110alpha was also required for this effect. Taken together, these findings demonstrate that LPS and D(3) use distinct isoforms of class I(A) PI3K to induce functional responses and that lentiviral-mediated delivery of shRNA is a powerful approach to study monocyte biology.

Calcitriol↗
PubMed2006

Cationized gelatin delivery of a plasmid DNA expressing small interference RNA for VEGF inhibits murine squamous cell carcinoma.

Double-stranded RNA (dsRNA) plays a major role in RNA interference (RNAi), a process in which segments of dsRNA are initially cleaved by the Dicer into shorter segments (21-23 nt) called small interfering RNA (siRNA). These siRNA then specifically target homologous mRNA molecules causing them to be degraded by cellular ribonucleases. RNAi down regulates endogenous gene expression in mammalian cells. Vascular endothelial growth factor (VEGF) is a key molecule in vasculogenesis as well as in angiogenesis. Tumor growth is an angiogenesis-dependent process, and therapeutic strategies aimed at inhibiting angiogenesis are theoretically attractive. To investigate the feasibility of using siRNA for VEGF in the specific knockdown of VEGF mRNA, thereby inhibiting angiogenesis, we have performed experiments with a DNA vector based on a siRNA system that targets VEGF (siVEGF). It almost completely inhibited the expression of three different isoforms (VEGF120, VEGF164 and VEGF188) of VEGF mRNA and the secretion of VEGF protein in mouse squamous cell carcinoma NRS-1 cells. The siVEGF released from cationized gelatin microspheres suppressed tumor growth in vivo. A marked reduction in vascularity accompanied the inhibition of a siVEGF-transfected tumor. Fluorescent microscopic study showed that the complex of siVEGF with cationized gelatin microspheres was still present around the tumor 10 days after injection, while free siVEGF had vanished by that time. siVEGF gene therapy increased the fraction of vessels covered by pericytes and induced expression of angiopoietin-1 by pericytes. These data suggest that cationized-gelatin microspheres containing siVEGF can be used to normalize tumor vasculature and inhibit tumor growth in a NRS-1 squamous cell carcinoma xenograft model.

Angiopoietin-1↗
PubMed2006

The lack of inhibition of porcine endogenous retrovirus by small interference RNA designed from the long terminal regions.

Xenotransplantation from pigs may offer a potential solution to the organ shortage. However, there remains the risk of xenoinfection by porcine endogenous retroviruses (PERVs) that cannot be eliminated by breeding pigs under specified pathogen-free conditions. RNA interference is a new method to inhibit the expression of a specific gene. Here, we designed two siRNAs from the long terminal repeat of PERV. Our results showed that these siRNAs had no inhibitory effects. The possible reasons for this are an off-target effect or a problem with specific sequence of RNAi. Future work should focus on siRNAs from conserved regions of other PERV genes.

Animals↗
PubMed2005

Inactivation of sortilin (a novel lysosomal sorting receptor) by dominant negative competition and RNA interference.

To assess the role of sortilin in the sorting and trafficking of sphingolipid activator proteins (SAPs) the function of sortilin was abolished by a dominant-negative mutant and by the use of RNAi. Mutant sortilin lacking the carboxyl-terminal region that contains the sorting signal abolished the trafficking of SAPs to the lysosomes. Both sortilin and SAPs were retained in the Golgi apparatus. The use of chemically synthesized siRNA effectively blocked the trafficking of SAPs to the lysosomes as well. Additionally, we created a stable COS-7 cell line transfected with the pSilencer 3.1 H1 neo vector containing a selected siRNA template oligonucleotide (small hairpin interference RNA) where the levels of sortilin were greatly suppressed. The elimination of sortilin by this method will permit to determine whether or not sortilin is involved in a general mechanism of lysosomal sorting that involves the trafficking of various soluble lysosomal proteins other than SAPs.

Journal Article↗
PubMed2006

Suppression of discoidin domain receptor 1 by RNA interference attenuates lung inflammation.

Discoidin domain receptor 1 (DDR1) is a receptor tyrosine kinase whose ligand is collagen. Recently, we have reported the association of DDR1 in the cytokine production of human leukocytes in in vitro and in vivo expression in idiopathic pulmonary fibrosis. However, its role in in vivo inflammation has not been fully elucidated. Small interference RNA (siRNA) can induce specific suppression of in vitro and in vivo gene expression. In this study, using a bleomycin-induced pulmonary fibrosis mouse model, we administered siRNA against DDR1 transnasally and evaluated histological changes, cytokine expression, and signaling molecule activation in the lungs. Histologically, siRNA against DDR1 successfully reduced in vivo DDR1 expression and attenuated bleomycin-induced infiltration of inflammatory cells. Furthermore, it significantly reduced inflammatory cell counts and concentrations of cytokines such as MCP-1, MIP-1alpha, and MIP-2 in bronchoalveolar lavage fluid. Subsequently, bleomycin-induced up-regulation of TGF-beta in bronchoalveolar lavage fluid was significantly inhibited, and collagen deposition in the lungs was reduced. Furthermore, siRNA against DDR1 significantly inhibited bleomycin-induced P38 MAPK activation in the lungs. Considered together, we propose that DDR1 contributes to the development of bleomycin-induced pulmonary inflammation and fibrosis.

Administration, Intranasal↗
PubMed2006

[Suppression of telomerase activity by plasmid-mediated RNA interference].

This study was aimed to construct a plasmid expressing siRNA specific for the human telomerase reverse transcriptase (hTERT) gene and to evaluate the ability of small interference RNA(siRNA) for inhibiting telomerase activity in HeLa cells. 64 nucleotides, in which 19 nt were homologous with hTERT gene, were chemically synthesized, annealed and linked into pSUPER to get pSUP-hTE. Then pSUP-hTE was digested with enzyme. We obtained its fragmant concluding promoter and 64nt. So we cloned it into pEGFP-C1 for constructing pEGFP-hTE which contains neo gene and the enhanced green fluorescent protein (EGFP). Recombinant pEGFP-hTE was transfected to HeLa cells. These cells were screened with medium containing G418. When stable colonies appeared, G418-resistant cells were harvested and propagated. At the different cell generations, hTERT mRNA and protein expression, telomerase activity and cell growth activity were analyzed. Compared with control cells, HeLa cells transfected with pEGFP-hTE showed that hTERT mRNA level and hTERT protein expression decreased and telomerase activity reduced by 38%, but the cells growth activity displayed no changes. So pEGFP-hTE could specifically inhibit expression of hTERT and telomerase activity. These results suggested that siRNA targeting hTERT gene might provide a new strategy for cancer biotherapy.

Base Sequence↗
PubMed2003

RNA interference blocks gene expression and RNA synthesis from hepatitis C replicons propagated in human liver cells.

RNA interference represents an exciting new technology that could have therapeutic applications for the treatment of viral infections. Hepatitis C virus (HCV) is a major cause of chronic liver disease and affects >270 million individuals worldwide. The HCV genome is a single-stranded RNA that functions as both a messenger RNA and replication template, making it an attractive target for the study of RNA interference. Double-stranded small interfering RNA (siRNA) molecules designed to target the HCV genome were introduced through electroporation into a human hepatoma cell line (Huh-7) that contained an HCV subgenomic replicon. Two siRNAs dramatically reduced virus-specific protein expression and RNA synthesis to levels that were 90% less than those seen in cells treated with negative control siRNAs. These same siRNAs protected naive Huh-7 cells from challenge with HCV replicon RNA. Treatment of cells with synthetic siRNA was effective >72 h, but the duration of RNA interference could be extended beyond 3 weeks through stable expression of complementary strands of the interfering RNA by using a bicistronic expression vector. These results suggest that a gene-therapeutic approach with siRNA could ultimately be used to treat HCV.

Antibodies, Monoclonal↗
PubMed2005

Poliovirus escape from RNA interference: short interfering RNA-target recognition and implications for therapeutic approaches.

Short interfering RNAs (siRNAs) directed against poliovirus and other viruses effectively inhibit viral replication. Although RNA interference (RNAi) may provide the basis for specific antiviral therapies, the limitations of RNAi antiviral strategies are ill defined. Here, we show that poliovirus readily escapes highly effective siRNAs through unique point mutations within the targeted regions. Competitive analysis of the escape mutants provides insights into the basis of siRNA recognition. The RNAi machinery can tolerate mismatches but is exquisitely sensitive to mutations within the central region and the 3' end of the target sequence. Indeed, specific mutations in the target sequence resulting in G:U mismatches are sufficient for the virus to escape siRNA inhibition. However, using a pool of siRNAs to simultaneously target multiple sites in the viral genome prevents the emergence of resistant viruses. Our study uncovers the elegant precision of target recognition by the RNAi machinery and provides the basis for the development of effective RNAi-based therapies that prevent viral escape.

Conserved Sequence↗
PubMed2002

Fragile X-related protein and VIG associate with the RNA interference machinery.

RNA interference (RNAi) is a flexible gene silencing mechanism that responds to double-stranded RNA by suppressing homologous genes. Here, we report the characterization of RNAi effector complexes (RISCs) that contain small interfering RNAs and microRNAs (miRNAs). We identify two putative RNA-binding proteins, the Drosophila homolog of the fragile X mental retardation protein (FMRP), dFXR, and VIG (Vasa intronic gene), through their association with RISC. FMRP, the product of the human fragile X locus, regulates the expression of numerous mRNAs via an unknown mechanism. The possibility that dFXR, and potentially FMRP, use, at least in part, an RNAi-related mechanism for target recognition suggests a potentially important link between RNAi and human disease.

Amino Acid Sequence↗
PubMed2006

Inhibition of viruses by RNA interference.

RNA-mediated interference (RNAi) is a recently discovered process by which dsRNA is able to silence specific gene functions. Although initially described in plants, nematodes and Drosophila, the process is currently considered to be an evolutionarily conserved process that is present in the entire eukaryotic kingdom in which its original function was as a defense mechanism against viruses and foreign nucleic acids. Similarly to the silencing of genes by RNAi, viral functions can be also silenced by the same mechanism, through the introduction of specific dsRNA molecules into cells, where they are targeted to essential genes or directly to the viral genome in case RNA viruses, thus arresting viral replication. Since the pioneering work of Elbashir and coworkers, who identified RNAi activity in mammalian cells, many publications have described the inhibition of viruses belonging to most if not all viral families, by targeting and silencing diverse viral genes as well as cell genes that are essential for virus replication. Moreover, virus expression vectors were developed and used as vehicles with which to deliver siRNAs into cells. This review will describe the use of RNAi to inhibit virus replication directly, as well as through the silencing of the appropriate cell functions.

Animals↗
PubMedDate not supplied

Uncover genetic interactions in Caenorhabditis elegans by RNA interference.

RNA-mediated interference (RNAi) has emerged recently as one of the most powerful functional genomics tools. RNAi has been particularly effective in the nematode worm C. elegans where RNAi has been used to analyse the loss-of-function phenotypes of almost all predicted genes. In this review, we illustrate how RNAi has been used to analyse gene function in C. elegans as well as pointing to some future directions for using RNAi to examine genetic interactions in a systematic manner.

Animals↗
PubMed2003

Induction of RNA interference using short interfering RNA expression vectors in cell culture and animal systems.

RNA interference, (RNAi) is a phenomenon by which the introduction of double stranded RNA (dsRNA) into cells induces targeted degradation of RNA molecules with homologous sequences. In the laboratory, RNAi has become a valuable tool for analysis of gene function through suppression of specific gene products. In addition, RNAi has shown great promise for use in therapeutic strategies designed to suppress the expression of pathogenic genes. In this review, viral expression and animal model systems that indicate the potential benefits of RNAi will be discussed. The major obstacle for the use of short interfering RNA in a laboratory or clinical setting is the need for efficient and sustained delivery of dsRNA to mammalian cells. Here, current methods that are being used to induce RNAi, both in cultured cells and in animal models, will be described with a focus on some of the most promising applications.

Animals↗
PubMed2006

Inhibition of human immunodeficiency virus type 1 by RNA interference using long-hairpin RNA.

Inhibition of virus replication by means of RNA interference has been reported for several important human pathogens, including human immunodeficiency virus type 1 (HIV-1). RNA interference against these pathogens has been accomplished by introduction of virus-specific synthetic small interfering RNAs (siRNAs) or DNA constructs encoding short-hairpin RNAs (shRNAs). Their use as therapeutic antiviral against HIV-1 is limited, because of the emergence of viral escape mutants. In order to solve this durability problem, we tested DNA constructs encoding virus-specific long-hairpin RNAs (lhRNAs) for their ability to inhibit HIV-1 production. Expression of lhRNAs in mammalian cells may result in the synthesis of many siRNAs targeting different viral sequences, thus providing more potent inhibition and reducing the chance of viral escape. The lhRNA constructs were compared with in vitro diced double-stranded RNA and a DNA construct encoding an effective nef-specific shRNA for their ability to inhibit HIV-1 production in cells. Our results show that DNA constructs encoding virus-specific lhRNAs are capable of inhibiting HIV-1 production in a sequence-specific manner, without inducing the class I interferon genes.

Animals↗
PubMed2004

Different effects on ACC oxidase gene silencing triggered by RNA interference in transgenic tomato.

RNA interference (RNAi) is a potent trigger for specific gene silencing of expression in a number of organisms and is an efficient way of shutting down gene expression. 1-Aminocyclopropane-1-carboxylate (ACC) oxidase catalyzes the oxidation of ACC to ethylene, a plant growth regulator that plays an important role in the tomato ripening process. In this research, to produce double-stranded (ds)RNA of tomato ACC oxidase, we linked the sense and antisense configurations of DNA fragments with 1,002-bp or 7-nt artificially synthesized fragments, respectively, and then placed these under the control of a modified cauliflower mosaic virus 35S promoter. The dsRNA expression unit was successfully introduced into tomato cultivar Hezuo 906 by Agrobacterium tumefaciens-mediated transformation. Molecular analysis of 183 transgenic plants revealed that the dsRNA unit was integrated into the tomato genome. With respect to the construct with the 1,002-bp linker, the severity of phenotypes indicated that 72.3% of the transformed plants had non-RNA interference, about 18.1% had semi-RNA interference, and only 9.6% had full-RNA interference. However when the construct with the 7-nt linker was used for transformation, the results were 13.0%, 18.0%, and 69.0%, respectively, indicating that the short linker was more efficient in RNAi of transgenic tomato plants. When we applied this fast way of shutting down the ACC oxidase gene, transgenic tomato plants were produced that had fruit which released traces of ethylene and had a prolonged shelf life of more than 120 days. The RNA and protein analyses indicated that there was non-RNA interference, semi-RNA interference and full-RNA interference of ACC oxidase in the transgenic tomato plants.

Agrobacterium tumefaciens↗
PubMed2003

Identification of a novel Drosophila gene, beltless, using injectable embryonic and adult RNA interference (RNAi).

BACKGROUND: RNA interference (RNAi) is a process triggered by a double-stranded RNA that leads to targeted down-regulation/silencing of gene expression and can be used for functional genomics; i.e. loss-of-function studies. Here we report on the use of RNAi in the identification of a developmentally important novel Drosophila (fruit fly) gene (corresponding to a putative gene CG5652/GM06434), that we named beltless based on an embryonic loss-of-function phenotype. RESULTS: Beltless mRNA is expressed in all developmental stages except in 0-6 h embryos. In situ RT-PCR localized beltless mRNA in the ventral cord and brain of late stage embryos and in the nervous system, ovaries, and the accessory glands of adult flies. RNAi was induced by injection of short (22 bp) beltless double-stranded RNAs into embryos or into adult flies. Embryonic RNAi altered cuticular phenotypes ranging from partially-formed to missing denticle belts (thus beltless) of the abdominal segments A2-A4. Embryonic beltless RNAi was lethal. Adult RNAi resulted in the shrinkage of the ovaries by half and reduced the number of eggs laid. We also examined Df(1)RK4 flies in which deletion removes 16 genes, including beltless. In some embryos, we observed cuticular abnormalities similar to our findings with beltless RNAi. After differentiating Df(1)RK4 embryos into those with visible denticle belts and those missing denticle belts, we assayed the presence of beltless mRNA; no beltless mRNA was detectable in embryos with missing denticle belts. CONCLUSIONS: We have identified a developmentally important novel Drosophila gene, beltless, which has been characterized in loss-of-function studies using RNA interference. The putative beltless protein shares homologies with the C. elegans nose resistant to fluoxetine (NRF) NRF-6 gene, as well as with several uncharacterized C. elegans and Drosophila melanogaster genes, some with prominent acyltransferase domains. Future studies should elucidate the role and mechanism of action of beltless during Drosophila development and in adults, including in the adult nervous system.

Amino Acid Sequence↗
PubMed2003

[RNA interference directed by small hairpin RNA expressed in COS-7 cells].

RNA interference is a phenomenon of gene silencing directed by double-stranded RNA. It can specifically inhibit gene expression by degrading mRNA efficiently and has been widely used to knockdown gene expression in Caenorhabditis elegans, Drosophila melanogaster, etc. For mammalian cells, dsRNA directed RNAi was detected only in murine undifferentiated ES or embryonic carcinoma (EC) cells. Our previous work proved the existence of RNAi effect for reporter gene GFP and endogenous gene Oct4 in undifferentiated murine ES cells. Yet in other kinds of mammalian cells, because of the existence of interferon pathway, long dsRNA will induce the cells to shutdown global protein translation and go to apoptosis. Therefore, dsRNA longer than 30 bp cannot be used to induce specific gene knockdown effect in these cells. Elbashir et al found that in vitro synthesized small interfering RNA (siRNA) (19-23 nt) could induce potent RNAi as effective as long dsRNA without showing unspecific effect, so that the interferon pathway could be bypassed. It was shown that during RNAi process, long dsRNA was first degraded into 19-23 nt siRNA and then recruited into RISC (RNA induced silencing complex) to degrade corresponding mRNA. However, the synthesis of siRNA is expensive and the effect is transient because the knockdown effect can only be maintained for about a week. Recently, it has been shown that U6 promoter directed small hairpin RNA (shRNA) can induce potent gene knockdown effect in murine P19 Embryonic Carcinoma cell. The RNAi effect of U6 promoter-driven shRNA corresponding to Green Fluorescence Protein (GFP) in COS-7 cells was checked. And it was found that the U6 promoter-driven shRNA for GFP can specifically and potently knockdown the GFP's expression in COS-7 cells. The result established the feasibility of using RNAi technique directed by U6 promoter-driven shRNA to study genes' function in COS-7 cell line.

Animals↗
PubMed2005

Design of siRNAs producing unstructured guide-RNAs results in improved RNA interference efficiency.

In RNA interference (RNAi), guide RNAs direct RNA-induced silencing complexes (RISC) to their mRNA targets, thus enabling the cleavage that leads to gene silencing. We describe a strong inverse correlation between the degree of guide-RNA secondary structure formation and gene silencing by small interfering (si)RNA. Unstructured guide strands mediate the strongest silencing whereas structures with base-paired ends are inactive. Thus, the availability of terminal nucleotides within guide structures determines the strength of silencing. A to G and C to U base exchanges, which involve wobble base-pairing with the target but preserve complementarity, turned inactive into active guide structures, thereby expanding the space of functional siRNAs. Previously observed base degenerations among mature micro (mi)RNAs together with the data presented here suggest a crucial role of the guide-RNA structures in miRNA action. The analysis of the effect of the secondary structures of guide-RNA sequences on RNAi efficiency provides a basis for better understanding RNA silencing pathways and improving the design of siRNAs.

Algorithms↗