SiPools: highly complex but accurately defined siRNA pools eliminate Off-target effects
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE57674 | GEO | 2014/05/15
SECONDARY ACCESSION(S): PRJNA247539
REPOSITORIES: GEO
Similar Datasets
Project description:Short interfering RNAs (siRNAs) are widely used as tool for gene inactivation in basic research and therapeutic applications. One of the major shortcomings of siRNA experiments are sequence-specific off-target effects. Such effects are largely unpredictable because siRNAs can affect partially complementary sequences and function like microRNAs (miRNAs), which inhibit gene expression on mRNA stability or translational levels. Here we demonstrate that novel, enzymatically generated siRNA pools-referred to as siPools-containing up to 60 accurately defined siRNAs eliminate off-target effects. This is achieved by the low concentration of each individual siRNA diluting sequence-specific off-target effects below detection limits. In fact, whole transcriptome analyses reveal that single siRNA transfections can severely affect global gene expression. However, when complex siRNA pools are transfected, almost no transcriptome alterations are observed. Taken together, we present enzymatically produced complex but accurately defined siRNA pools with potent on-target silencing but without detectable off-target effects.
| S-EPMC4081087 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2014-05-15 | E-GEOD-57674 | biostudies-arrayexpress
Project description:Short interfering RNAs (siRNA) are widely used as tool for gene inactivation in basic research and therapeutic applications. One of the major shortcomings of siRNA experiments are sequence-specific Off-target effects. Such effects are largely unpredictable because siRNAs can affect partially complementary sequences and function like microRNAs (miRNAs), which inhibit gene expression on mRNA stability or translational levels. Here we demonstrate that novel, enzymatically generated siRNA pools - referred to as siPools - containing up to 60 accurately defined siRNAs eliminate Off-target effects. This is achieved by the low concentration of each individual siRNA diluting sequence-specific Off-target effects below detection limits. In fact, whole transcriptome analyses reveal that single siRNA transfections can severely affect global gene expression. However, when complex siRNA pools are transfected, almost no transcriptome alterations are observed. Taken together, we present enzymatically-produced complex but accurately defined siRNA pools with potent On-target silencing but without detectable Off-target effects.
2014-05-15 | GSE57646 | GEO
Project description:Short interfering RNAs (siRNA) are widely used as tool for gene inactivation in basic research and therapeutic applications. One of the major shortcomings of siRNA experiments are sequence-specific Off-target effects. Such effects are largely unpredictable because siRNAs can affect partially complementary sequences and function like microRNAs (miRNAs), which inhibit gene expression on mRNA stability or translational levels. Here we demonstrate that novel, enzymatically generated siRNA pools - referred to as siPools - containing up to 60 accurately defined siRNAs eliminate Off-target effects. This is achieved by the low concentration of each individual siRNA diluting sequence-specific Off-target effects below detection limits. In fact, whole transcriptome analyses reveal that single siRNA transfections can severely affect global gene expression. However, when complex siRNA pools are transfected, almost no transcriptome alterations are observed. Taken together, we present enzymatically-produced complex but accurately defined siRNA pools with potent On-target silencing but without detectable Off-target effects. dsRNA fragments of more than 30bp length may trigger interferon response in mammalian cells, depending on the cell type as well as length and concentration of the dsRNA. To demonstrate that complex siRNA pools (siPools) do not contain trace amounts of such longer dsRNA species and therefore do not trigger interferon response, MCF7 cells which exhibit sensitive interferon response, were transfected with a siPool targeting human SCYL1, consisting of 60 siRNA at a total siRNA concentration of 3nM. As positive control, MCF7 cells were transfected with an RNAseIII generated mixture of dsRNAs (esiRNAs) at equal concentration (weight/volume). Mock transfected cells served as negative control. Every sample was tested in biological triplicates. Total RNA was extract 48h after transfection for affimetrix expression analysis.
2014-05-15 | E-GEOD-57646 | biostudies-arrayexpress
Project description:Short interfering RNAs (siRNA) are widely used as tool for gene inactivation in basic research and therapeutic applications. One of the major shortcomings of siRNA experiments are sequence-specific Off-target effects. Such effects are largely unpredictable because siRNAs can affect partially complementary sequences and function like microRNAs (miRNAs), which inhibit gene expression on mRNA stability or translational levels. Here we demonstrate that novel, enzymatically generated siRNA pools - referred to as siPools - containing up to 60 accurately defined siRNAs eliminate Off-target effects. This is achieved by the low concentration of each individual siRNA diluting sequence-specific Off-target effects below detection limits. In fact, whole transcriptome analyses reveal that single siRNA transfections can severely affect global gene expression. However, when complex siRNA pools are transfected, almost no transcriptome alterations are observed. Taken together, we present enzymatically-produced complex but accurately defined siRNA pools with potent On-target silencing but without detectable Off-target effects.
2014-05-15 | GSE57667 | GEO
Project description:Short interfering RNAs (siRNA) are widely used as tool for gene inactivation in basic research and therapeutic applications. One of the major shortcomings of siRNA experiments are sequence-specific Off-target effects. Such effects are largely unpredictable because siRNAs can affect partially complementary sequences and function like microRNAs (miRNAs), which inhibit gene expression on mRNA stability or translational levels. Here we demonstrate that novel, enzymatically generated siRNA pools - referred to as siPools - containing up to 60 accurately defined siRNAs eliminate Off-target effects. This is achieved by the low concentration of each individual siRNA diluting sequence-specific Off-target effects below detection limits. In fact, whole transcriptome analyses reveal that single siRNA transfections can severely affect global gene expression. However, when complex siRNA pools are transfected, almost no transcriptome alterations are observed. Taken together, we present enzymatically-produced complex but accurately defined siRNA pools with potent On-target silencing but without detectable Off-target effects. To demonstrate the reduction of Off-target gene deregulation by use of complex siRNA pools (siPools), a single siRNA targeting human SCYL1 was transfected alone or in combination with 14 or 59 other siRNAs at a total siRNA concentration of 3 nM in human Hela cells. Mock transfected cells served as negative control. Every sample was tested in biological triplicates. Total RNA was extract 48h after transfection for affimetrix expression analysis.
2014-05-15 | E-GEOD-57667 | biostudies-arrayexpress
Project description:BACKGROUND: Gene knock down by RNAi is a highly effective approach to silence gene expression in experimental as well as therapeutic settings. However, this widely used methodology entails serious pitfalls, especially concerning specificity of the RNAi molecules. RESULTS: We tested the most widely used control siRNA directed against GFP for off-target effects and found that it deregulates in addition to GFP a set of endogenous target genes. The off-target effects were dependent on the amount of GFP siRNA transfected and were detected in a variety of cell lines. Since the respective siRNA molecule specific for GFP is widely used as negative control for RNAi experiments, we studied the complete set of off-target genes of this molecule by genome-wide expression profiling. The detected modulated mRNAs had target sequences homologous to the siRNA as small as 8 basepairs in size. However, we found no restriction of sequence homology to 3'UTR of target genes. CONCLUSION: We can show that even siRNAs without a physiological target have sequence-specific off-target effects in mammalian cells. Furthermore, our analysis defines the off-target genes affected by the siRNA that is commonly used as negative control and directed against GFP. Since off-target effects can hardly be avoided, the best strategy is to identify false positives and exclude them from the results. To this end, we provide the set of false positive genes deregulated by the commonly used GFP siRNA as a reference resource for future siRNA experiments.
| S-EPMC2443166 | biostudies-literature
Project description:Short interfering RNAs (siRNAs) are promising therapeutics that make use of the RNA interference (RNAi) pathway, but liabilities arising from the native RNA structure necessitate chemical modification for drug development. Advances in the structural characterization of components of the human RNAi pathway have enabled structure-guided optimization of siRNA properties. Here we report the 2.3 Å resolution crystal structure of human Argonaute 2 (hAgo2), a key nuclease in the RNAi pathway, bound to an siRNA guide strand bearing an unnatural triazolyl nucleotide at position 1 (g1). Unlike natural nucleotides, this analogue inserts deeply into hAgo2's central RNA binding cleft and thus is able to modulate pairing between guide and target RNAs. The affinity of the hAgo2-siRNA complex for a seed-only matched target was significantly reduced by the triazolyl modification, while the affinity for a fully matched target was unchanged. In addition, siRNA potency for off-target repression was reduced (4-fold increase in IC50) by the modification, while on-target knockdown was improved (2-fold reduction in IC50). Controlling siRNA on-target versus microRNA (miRNA)-like off-target potency by projection of substituent groups into the hAgo2 central cleft from g1 is a new approach to enhance siRNA selectivity with a strong structural rationale.
| S-EPMC4962782 | biostudies-literature
Project description:siDirect (http://design.RNAi.jp/) is a web-based online software system for computing highly effective small interfering RNA (siRNA) sequences with maximum target-specificity for mammalian RNA interference (RNAi). Highly effective siRNA sequences are selected using novel guidelines that were established through an extensive study of the relationship between siRNA sequences and RNAi activity. Our efficient software avoids off-target gene silencing to enumerate potential cross-hybridization candidates that the widely used BLAST search may overlook. The website accepts an arbitrary sequence as input and quickly returns siRNA candidates, providing a wide scope of applications in mammalian RNAi, including systematic functional genomics and therapeutic gene silencing.
| S-EPMC441580 | biostudies-literature
Project description:Small interfering RNAs (siRNAs) are important tools for knocking down targeted genes, and have been widely applied to biological and biomedical research. To design siRNAs, two important aspects must be considered: the potency in knocking down target genes and the off-target effect on any nontarget genes. Although many studies have produced useful tools to design potent siRNAs, off-target prevention has mostly been delegated to sequence-level alignment tools such as BLAST. We hypothesize that whole-genome thermodynamic analysis can identify potential off-targets with higher precision and help us avoid siRNAs that may have strong off-target effects. To validate this hypothesis, two siRNA sets were designed to target three human genes IDH1, ITPR2 and TRIM28. They were selected from the output of two popular siRNA design tools, siDirect and siDesign. Both siRNA design tools have incorporated sequence-level screening to avoid off-targets, thus their output is believed to be optimal. However, one of the sets we tested has off-target genes predicted by Picky, a whole-genome thermodynamic analysis tool. Picky can identify off-target genes that may hybridize to a siRNA within a user-specified melting temperature range. Our experiments validated that some off-target genes predicted by Picky can indeed be inhibited by siRNAs. Similar experiments were performed using commercially available siRNAs and a few off-target genes were also found to be inhibited as predicted by Picky. In summary, we demonstrate that whole-genome thermodynamic analysis can identify off-target genes that are missed in sequence-level screening. Because Picky prediction is deterministic according to thermodynamics, if a siRNA candidate has no Picky predicted off-targets, it is unlikely to cause off-target effects. Therefore, we recommend including Picky as an additional screening step in siRNA design.
| S-EPMC3590146 | biostudies-literature