A universal plasmid library encoding all permutations of small interfering RNA.
Ontology highlight
ABSTRACT:
SUBMITTER: Chen M
PROVIDER: S-EPMC548965 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Cationic polymers are potential intracellular carriers for small interfering RNA (siRNA). The short and rigid nature of an siRNA chain often results in larger and more loosely packed particles compared to plasmid DNA (pDNA) after complexing with carrier polycations, and in turn, poor silencing effects are seen against the target mRNAs. A helper polyanion, pDNA, was incorporated along with siRNA to form compact nanosized polyplexes. At C/A (cation/anion) ratios of 2 and 5, poly(l-lysine) (PLL)/siRNA-pGFP and PLL/siRNA-pGFP-OSDZ (oligomeric sulfadiazine (OSDZ) for endosomolysis) complexes produced particles 90-150 nm in size with a 15-45 mV surface charge, while PLL/siRNA complexes yielded particles 1-2 ?m in size at the same C/A ratios. The PLL/siRNA-pGFP (C/A 2) complexes showed significantly higher specific gene silencing (50-90% vs. 10-25%) than the complexes formed at C/A 5. PLL/siRNA-pGFP-OSDZ (C/A 2) complexes improved the specific gene silencing (90%) more dramatically than PLL/siRNA-pGFP (C/A 2) complexes (50%), demonstrating a potential role for OSDZ. PLL/siRNA-pGFP-OSDZ (C/A 2) complexes sustained higher specific gene silencing compared with PLL/siRNA-pGFP (C/A 2) complexes. Other oligomeric sulfonamides (OSA) with varying pK(a) used in PLL/siRNA-pGFP-OSA complexes also caused effective gene silencing. The pGFP in the PLL/siRNA-pGFP complexes successfully expressed GFP protein without interfering with the siRNA. In conclusion, this study demonstrates that long pDNA helps effectively form nanosized siRNA particles and that OSA enhances specific gene silencing. In a single nucleic acid carrier formulation, co-delivery of siRNA and pDNA is feasible to maximize therapeutic effects or to include therapeutic or diagnostic functionalities.
| S-EPMC3095752 | biostudies-literature
Project description:The aim of the present study was to observe the in vivo targeting characteristic of angiopoietin 2-small interfering RNA (Ang2-siRNA) plasmid/chitosan magnetic nanoparticles in an established nude mouse model of malignant melanoma (MM) under an external magnetic field. The nude mouse MM model was first established, then divided into 3 groups, including the control group, the non-targeting group and the target group, the control group was given normal saline and the non-targeting and targeting groups were administrated particles through the tail vein; the non-targeting group was not under external magnetic field and the control group and the targeting group were under external magnetic field for 60 min. The mice were then sacrificed and the tumor tissues were stained with hematoxylin and eosin and Prussian blue in order to verify the particle distributions in the tumor tissues. The control group exhibited negative Prussian blue staining in the tumor tissues, the non-targeting group demonstrated weakly positive Prussian blue staining in tumor tissues and the targeting group revealed strongly positive Prussian blue staining in tumor tissues. Ang2-siRNA plasmid vector/chitosan magnetic nanoparticles directly moved towards tumor tissues under the action of external magnetic field, thus it demonstrated good targeting characteristic.
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Project description:RNA interference (RNAi) has become a gold standard for validating gene function in basic life science research and provides a promising therapeutic modality for cancer and other diseases. This mini-review focuses on the potential of small interfering RNAs (siRNAs) in anticancer treatment, including the establishment and screening of cancer-associated siRNA libraries and their applications in anticancer drug target discovery and cancer therapy. This article also describes the current delivery approaches of siRNAs using lipids, polymers, and, in particular, gold nanoparticles to induce significant gene silencing and tumor growth regression.
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Project description:Drosophila endogenous small RNAs are categorized according to their mechanisms of biogenesis and the Argonaute protein to which they bind. MicroRNAs are a class of ubiquitously expressed RNAs of approximately 22 nucleotides in length, which arise from structured precursors through the action of Drosha-Pasha and Dicer-1-Loquacious complexes. These join Argonaute-1 to regulate gene expression. A second endogenous small RNA class, the Piwi-interacting RNAs, bind Piwi proteins and suppress transposons. Piwi-interacting RNAs are restricted to the gonad, and at least a subset of these arises by Piwi-catalysed cleavage of single-stranded RNAs. Here we show that Drosophila generates a third small RNA class, endogenous small interfering RNAs, in both gonadal and somatic tissues. Production of these RNAs requires Dicer-2, but a subset depends preferentially on Loquacious rather than the canonical Dicer-2 partner, R2D2 (ref. 14). Endogenous small interfering RNAs arise both from convergent transcription units and from structured genomic loci in a tissue-specific fashion. They predominantly join Argonaute-2 and have the capacity, as a class, to target both protein-coding genes and mobile elements. These observations expand the repertoire of small RNAs in Drosophila, adding a class that blurs distinctions based on known biogenesis mechanisms and functional roles.
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Project description:Andes virus (ANDV) is the most common causative agent of hantavirus pulmonary syndrome (HPS) in the Americas, and is the only hantavirus associated with human-to-human transmission. Case fatality rates of ANDV-induced HPS are approximately 40%. There are currently no effective vaccines or antivirals against ANDV. Since HPS severity correlates with viral load, we tested small interfering RNA (siRNA) directed against ANDV genes as a potential antiviral strategy. We designed pools of 4 siRNAs targeting each of the ANDV genome segments (S, M, and L), and tested their efficacy in reducing viral replication in vitro. The siRNA pool targeting the S segment reduced viral transcription and replication in Vero-E6 cells more efficiently than those targeting the M and L segments. In contrast, siRNAs targeting the S, M, or L segment were similar in their ability to reduce viral replication in human lung microvascular endothelial cells. Importantly, these siRNAs inhibit ANDV replication even if given after infection. Taken together, our findings indicate that siRNAs targeting the ANDV genome efficiently inhibit ANDV replication, and show promise as a strategy for developing therapeutics against ANDV infection.
| S-EPMC4055710 | biostudies-literature
Project description:Epirubicin has been widely used for chemotherapeutic treatment of gastric cancer; however, intrinsic and acquired chemoresistance remains an obstacle to successful management. The mechanisms underlying epirubicin resistance are still not well defined. Here we report the construction and application of a partially randomized retrovirus library of 4 x 10(6) small interfering RNAs to identify novel genes whose suppression confers epirubicin resistance in gastric cancer cells SGC7901. From 12 resistant cell colonies, two small interfering RNAs targeting GAS1 (growth arrest-specific 1) and PTEN (phosphatase and tensin homolog), respectively, were identified and validated. We identified a previously unrecognized chemoresistance role for GAS1. GAS1 suppression resulted in significant epirubicin resistance and cross-resistance to 5-fluorouracil and cisplatin in various gastric cancer cell lines. GAS1 suppression promoted multidrug resistance through apoptosis inhibition, partially by up-regulating the Bcl-2/Bax ratio that was abolished by Bcl-2 inhibition. GAS1 suppression induced chemoresistance partially by increasing drug efflux in an ATP-binding cassette transporter and drug-dependent manner. P-glycoprotein (P-gp) and BCRP (breast cancer resistance protein) but not MRP-1 were up-regulated, and targeted knockdown of P-gp and BCRP could partially reverse GAS1 suppression-induced epirubicin resistance. Verapamil, a P-gp inhibitor, could reverse P-gp substrate (epirubicin) but not non-P-gp substrate (5-fluorouracil and cisplatin) resistance in GAS1-suppressed gastric cancer cells. BCRP down-regulation could partially reverse 5-fluorouracil but not cisplatin resistance induced by GAS1 suppression, suggesting 5-fluorouracil but not cisplatin was a BCRP substrate. These results suggest that GAS1 might be a target to overcome multidrug resistance and provide a novel approach to identifying candidate genes that suppress chemoresistance of gastric cancers.
| S-EPMC2785315 | biostudies-literature
Project description:RNA interference (RNAi) is a powerful approach for silencing genes associated with a variety of pathologic conditions; however, in vivo RNAi delivery has remained a major challenge due to lack of safe, efficient, and sustained systemic delivery. Here, we report on a novel approach to overcome these limitations using a multistage vector composed of mesoporous silicon particles (stage 1 microparticles, S1MP) loaded with neutral nanoliposomes (dioleoyl phosphatidylcholine, DOPC) containing small interfering RNA (siRNA) targeted against the EphA2 oncoprotein, which is overexpressed in most cancers, including ovarian. Our delivery methods resulted in sustained EphA2 gene silencing for at least 3 weeks in two independent orthotopic mouse models of ovarian cancer following a single i.v. administration of S1MP loaded with EphA2-siRNA-DOPC. Furthermore, a single administration of S1MP loaded with-EphA2-siRNA-DOPC substantially reduced tumor burden, angiogenesis, and cell proliferation compared with a noncoding control siRNA alone (SKOV3ip1, 54%; HeyA8, 57%), with no significant changes in serum chemistries or in proinflammatory cytokines. In summary, we have provided the first in vivo therapeutic validation of a novel, multistage siRNA delivery system for sustained gene silencing with broad applicability to pathologies beyond ovarian neoplasms.
| S-EPMC3202607 | biostudies-literature
Project description:Clinical application of small interfering RNA (siRNA) requires safe and efficient delivery in vivo. Here, we report the design and synthesis of lipid nanoparticles (LNPs) for siRNA delivery based on cationic lipids with multiple tertiary amines and hydrophobic linoleyl chains. LNPs incorporating the lipid containing tris(2-aminoethyl)amine (TREN) and 3 linoleyl chains, termed TRENL3, were found to have exceptionally high siRNA transfection efficacy that was markedly superior to lipofectamine, a commercial transfection agent. In addition, inclusion of polyunsaturated fatty acids, such as linoleic acid and linolenic acid in the formulation further enhanced the siRNA delivery efficiency. TRENL3 LNPs were further shown to transport siRNA into the cytosol primarily via macropinocytosis rather than clathrin-mediated endocytosis. The new LNPs have demonstrated preferential uptake by the liver and hepatocellular carcinoma in mice, thereby leading to high siRNA gene-silencing activity. These data suggest potential therapeutic applications of TRENL3 mediated delivery of siRNA for liver diseases.
| S-EPMC3374058 | biostudies-literature
Project description:The Drosophila melanogaster RNA-induced silencing complex (RISC) forms a large ribonucleoprotein particle on small interfering RNAs (siRNAs) and catalyzes target mRNA cleavage during RNA interference (RNAi). Dicer-2, R2D2, Loquacious, and Argonaute-2 are examples of RISC-associated factors that are involved in RNAi. Holo-RISC is an approximately 80 S small interfering ribonucleoprotein, which suggests that there are many additional proteins that participate in the RNAi pathway. In this study, we used siRNA affinity capture combined with mass spectrometry to identify novel components of the Drosophila RNAi machinery. Our study identified both established RISC components and novel siRNA-associated factors, many of which contain domains that are consistent with potential roles in RNAi. Functional analysis of these novel siRNA-associated proteins suggests that these factors may play an important role in RNAi.
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Project description:RNA silencing (also known as RNA interference) is a conserved biological response to double-stranded RNA that regulates gene expression, and has evolved in plants as a defence against viruses. The response is mediated by small interfering RNAs (siRNAs), which guide the sequence-specific degradation of cognate messenger RNAs. As a counter-defence, many viruses encode proteins that specifically inhibit the silencing machinery. The p19 protein from the tombusvirus is such a viral suppressor of RNA silencing and has been shown to bind specifically to siRNA. Here, we report the 1.85-A crystal structure of p19 bound to a 21-nucleotide siRNA, where the 19-base-pair RNA duplex is cradled within the concave face of a continuous eight-stranded beta-sheet, formed across the p19 homodimer interface. Direct and water-mediated intermolecular contacts are restricted to the backbone phosphates and sugar 2'-OH groups, consistent with sequence-independent p19-siRNA recognition. Two alpha-helical 'reading heads' project from opposite ends of the p19 homodimer and position pairs of tryptophans for stacking over the terminal base pairs, thereby measuring and bracketing both ends of the siRNA duplex. Our structure provides an illustration of siRNA sequestering by a viral protein.
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