Evidence of off-target effects associated with long dsRNAs in Drosophila cell-based assays
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ABSTRACT: To evaluate the specificity of long dsRNAs used in high-throughput RNAi screens performed at the Drosophila RNAi Screening Center (DRSC), we performed a global analysis of their activity in 30 genome-wide screens completed at our facility. Surprisingly, our analysis predicts that dsRNAs containing ≥19 nucleotide perfect matches identified in silico to unintended targets may contribute to a significant false positive error rate arising from off-target effects. We confirmed experimentally that such sequences in dsRNAs lead to false positives and to the efficient knockdown of a cross-hybridizing transcript, raising a cautionary note when interpreting results based on the use of a single dsRNA per gene. Although a full appreciation of all causes of false positive errors remains to be determined, we suggest simple guidelines to help ensure high quality information from RNAi high-throughput screens Keywords: Specificity of long dsRNAs, Drosophila melanogaster, SL2 cell line, custom cDNA arrays, off-target effects, Drosophila RNAi Screening Center (DRSC)
Project description:RNA interference (RNAi) is a gene-silencing mechanism triggered by the cytosolic entry of double-stranded RNAs (dsRNAs). Many animal cells internalize extracellular dsRNAs via endocytosis for RNAi induction. However, it is not clear how the endocytosed dsRNAs are translocated into the cytosol across the endo/lysosomal membrane. Herein, we show that in Drosophila S2 cells, endocytosed dsRNAs induce lysosomal membrane permeabilization (LMP) that allows cytosolic dsRNA translocation. LMP mediated by dsRNAs requires the lysosomal Cl−/H+ antiporter ClC-b/DmOstm1. In clc-b or dmostm1 knockout S2 cells, extracellular dsRNAs are endocytosed and reach the lysosomes normally but fail to enter the cytosol. Pharmacological induction of LMP restores extracellular dsRNA-directed RNAi in clc-b or dmostm1-knockout cells. Furthermore, clc-b or dmostm1 mutant flies are defective in extracellular dsRNA-directed RNAi and its associated antiviral immunity. Therefore, endocytosed dsRNAs have an intrinsic ability to induce ClC-b/DmOstm1-dependent LMP that allows cytosolic dsRNA translocation for RNAi responses in Drosophila cells.
Project description:Deep Sequencing of mRNA from the Drosophila melanogaster S2-DRSC cells that have been RNAi depleted of mRNAs encoding RNA binding proteins. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf
Project description:Deep Sequencing of mRNA from the Drosophila melanogaster S2-DRSC cells that have been RNAi depleted of mRNAs encoding RNA binding proteins. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf Analysis of Poly(A)+ RNA from S2-DRSC Cells depleted of mRNAs encoding RNA binding proteins
Project description:We analyzed the expression of dsRNAs in control and p53 restored 2153L GEM tumors upon different treatments. Our ChIP-seq and RNA-seq experiments showed that the restored p53 bound to the regulatory regions of dsRNA-containing genes that account for 91% of the total dsRNA abundance in combination therapy–treated 2153L tumors, and suppressed their expression upon combination therapy. The abundance of dsRNA (TPM) was calculated from the dsRIP experiment.
Project description:Deep Sequencing of mRNA from the Drosophila melanogaster cell lines Kc167, CME_W1_Cl.8+, S2-DRSC and ML-DmBG3-c2. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf
Project description:We sought to determine the genes regulated by the Drosophila Hox protein AbdA in a homogenous cell system. S2-DRSC cells that have no Hox expression were stably transfected with HA-tagged AbdA under the control of a metallothionein promoter.
Project description:It has long been appreciated that striped pair-rule transcription factor expression is necessary for convergent extension in the early Drosophila embryo, although the mechanisms that link these transcriptional regulators to planar polarity in this tissue have long been elusive. The goal of this study was to determine the transcriptional tragets of the pair-rule transcription factors Eve and Runt in Drosophila blastoderm embryos. We compared the transcriptional profiles of late blastoderm embryos injected with either water or dsRNAs against both eve and runt to identify differentially expressed genes that may directly contribute to the establishment of planar polarity during Drosophila convergent extension. Comparing the mRNA profiles from late blastoderm Drosophila embryos injected with either water (Water) or eve+runt dsRNAs (Eve), in triplicate, using Illumina HiSeq.
Project description:We developed an anti-dsRNA antibody co-immunoprecipitation coupled with quantitative mass spectrometry to comprehensively identify RBPs bound to cellular dsRNAs. To minimize false positives, we conducted a quantitative mass spectrometry analysis under two additional conditions: first, by treating the samples with RNase T1 to degrade single-stranded RNAs, and second, by performing a pull-down using synthetic double-stranded RNA, poly(I:C). The interactomes through these three methods provide an unbiased and thorough characterization of potential dsRBPs bound to cellular dsRNAs.