Single Alkyl Phosphonate Modification of the siRNA Backbone in the Seed Region Enhances Specificity and Therapeutic Profile
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PROVIDER: PRJNA1205781 | ENA |
REPOSITORIES: ENA
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Project description:We evaluated the effect of alkyl phosphonate linkages in enhancing the specificity and therapeutic profile of siRNA when incorporated into the seed region. Modified siRNAs with a single alkyl phosphonate linkage demonstrated improved specificity, particularly when positioned at the internucleotide linkage between positions 6 and 7 from the 5'-end of the guide strand. These modifications maintained robust on-target activity both in vitro and in vivo while significantly reducing off-target effects, as shown by differential gene expression analysis. Additionally, we observed enhanced safety in mice, as evidenced by reduced ALT/AST elevation and the absence of histopathological changes.
2025-01-15 | GSE285764 | GEO
Project description:Transfected siRNAs and miRNAs regulate numerous transcripts that have only limited complementarity to the active strand of the RNA duplex. This process reflects natural target regulation by miRNAs, but is an unintended (“off-target”) consequence of siRNA-mediated silencing. Here we demonstrate that this unintended off-target silencing is widespread, and occurs in a manner reminiscent of target silencing by miRNAs. A high proportion of unintended transcripts silenced by siRNAs showed 3’ UTR sequence complementarity to the seed region of the siRNA. Base mismatches within the siRNA seed region reduced the set of original off-target transcripts but generated new sets of silenced transcripts with sequence complementarity to the mismatched seed sequence. An inducible shRNA silenced a subset of transcripts that were silenced by an siRNA of the same sequence, demonstrating that unintended silencing is sequence-mediated and is independent of delivery method. In all cases, off-target transcript silencing was accompanied by loss of the corresponding protein and occurred with similar dependence on siRNA concentration as silencing of the target transcript. These results demonstrate that short stretches of sequence complementarity to the seed region of the siRNA are key to the silencing of unintended transcripts, and that this limits the specificity of siRNA-mediated transcript silencing. Because these off-target events are sequence-dependent, inclusion of multiple independent siRNAs to the target of interest can help to distinguish true positives from false positives in functional genetic analyses. Keywords: siRNA, RNAi, sequence alignment, off-target, seed region
2006-09-12 | GSE5814 | GEO
Project description:Transfected siRNAs and miRNAs regulate numerous transcripts that have only limited complementarity to the active strand of the RNA duplex. This process reflects natural target regulation by miRNAs, but is an unintended (â??off-targetâ??) consequence of siRNA-mediated silencing. Here we demonstrate that this unintended off-target silencing is widespread, and occurs in a manner reminiscent of target silencing by miRNAs. A high proportion of unintended transcripts silenced by siRNAs showed 3â?? UTR sequence complementarity to the seed region of the siRNA. Base mismatches within the siRNA seed region reduced the set of original off-target transcripts but generated new sets of silenced transcripts with sequence complementarity to the mismatched seed sequence. An inducible shRNA silenced a subset of transcripts that were silenced by an siRNA of the same sequence, demonstrating that unintended silencing is sequence-mediated and is independent of delivery method. In all cases, off-target transcript silencing was accompanied by loss of the corresponding protein and occurred with similar dependence on siRNA concentration as silencing of the target transcript. These results demonstrate that short stretches of sequence complementarity to the seed region of the siRNA are key to the silencing of unintended transcripts, and that this limits the specificity of siRNA-mediated transcript silencing. Because these off-target events are sequence-dependent, inclusion of multiple independent siRNAs to the target of interest can help to distinguish true positives from false positives in functional genetic analyses. For details, please see A.L. Jackson, et al. 2006. RNA 12(7): 1179-1187. We used consensus genelists for clustering. Please see attached tables for genelists.
2006-09-12 | E-GEOD-5814 | biostudies-arrayexpress
Project description:Pairing between the hexamer seed region of a small interfering RNA (siRNA) guide strand (nucleotides 2-7) and complementary sequences in the 3' UTR of mature transcripts has been implicated as an important element in off-target gene regulation and false positive phenotypes. To better understand the association between seed sequences and off-target profiles we performed an analysis of all possible (4096) hexamers and identified a nonuniform distribution of hexamer frequencies across the 3' UTR transcriptome. Subsequent microarray analysis of cells transfected with siRNAs having seeds with low, medium, or high seed complement frequencies (SCFs) revealed that duplexes with low SCFs generally induced fewer off-targets and off-target phenotypes than molecules with more abundant 3' UTR complements. These findings provide the first experimentally validated strategy for designing siRNAs with enhanced specificity and allow for more accurate interpretation of high throughput screening data generated with existing siRNA/shRNA collections.
| S-EPMC2327361 | biostudies-literature
Project description:dengue virus type 2 strain:ET300 backbone Raw sequence reads
| PRJNA1013032 | ENA
Project description:Malaria, caused by Plasmodium falciparum, remains a significant health burden. The barrier for developing anti-malarial drugs is the ability of the parasite to rapidly generate resistance. We previously demonstrated that Salinipostin A (SalA), a natural product, potently kills parasites by inhibiting multiple lipid metabolizing serine hydrolases, a mechanism with a low propensity for resistance. Given the difficulty of employing natural products as therapeutic agents, we synthesized a small library of lipidic mixed alkyl/aryl phosphonates as bioisosteres of SalA. Two constitutional isomers exhibited divergent anti-parasitic potencies which enabled the identification of therapeutically relevant targets. We also confirm that this compound kills parasites through a mechanism that is distinct from both SalA and the pan-lipase inhibitor, Orlistat. In addition, like SalA, our compound induces only weak resistance, attributable to mutations in a single protein involved in multidrug resistance. These data suggest that mixed alkyl/aryl phosphonates are a promising, synthetically tractable anti-malarials with a low-propensity to induce resistance.
2024-07-15 | PXD051499 | Pride
Project description:N2-alkyl-dG lesions trigger R-loop formation in genome
| PRJNA1042825 | ENA
Project description:New alkyl-phospholipids (APLs) that are structurally derived from the platelet-activating factor are promising candidates for anticancer treatment. After the incorporation into cell membranes, APLs are able to interfere with a wide variety of key enzymes implicated in cell growth, motility, invasion and apoptosis. Besides the prototype edelfosine, we presented a novel group of APLs, glycosidated phospholipids that efficiently inhibit cell proliferation. Two members of this group, Ino-C2-PAF and Glc-PAF, display high efficacy and low cytotoxicity in immortalized non-tumorigenic skin keratinocyte cell line HaCaT. However, the influence of APLs on the transcription of the whole genome is still unknown. Here, using Agilent cDNA microarray technology, we compared global gene expression profiles of HaCaT cells treated with edelfosine, Ino-C2-PAF or Glc-PAF with the profile of control cells. The influence of APLs on the transcriptional profile of immortalized keratinocytes (HaCaT) was analyzed treating HaCaT cells with respectively 5 M-BM-5M Ino-C2-PAF, Glc-PAF and edelfosine for 24 h. Control cells were left untreated. Three independent experiments were performed for each condition.
2011-03-01 | E-GEOD-20722 | biostudies-arrayexpress
Project description:The goal of this study was to determine genes affected by depletion of KDM4A in HEK293T cells This data was used in Van Rechem et. al. Cancer Discovery 2014 to demonstrate that depletion of KDM4A did not alter expression of genese associated with translation. The experiment uses two different shRNA constructs; shKDM4A.2 in a pSuper backbone and shKDM4A.6 in a pLKO backbone. A corresponding empty vector control was conducted for each backbone. Each shRNA was compared to its own control.
2015-03-31 | E-GEOD-63812 | biostudies-arrayexpress
Project description:RNA interference (RNAi) is a powerful tool for post-transcriptional gene silencing. However, the siRNA guide strand may bind unintended off-target transcripts via partial sequence complementarity by a mechanism closely mirroring micro RNA (miRNA) silencing. To better understand these off-target effects, we investigated the correlation between sequence features within various subsections of siRNA guide strands, and its corresponding target sequences, with off-target activities. Our results confirm previous reports that strength of base-pairing in the siRNA seed region is the primary factor determining the efficiency of off-target silencing. However, the degree of downregulation of off-target transcripts with shared seed sequence is not necessarily similar, suggesting that there are additional auxiliary factors that influence the silencing potential. Here, we demonstrate that both the melting temperature (Tm) in a subsection of siRNA non-seed region, and the GC contents of its corresponding target sequences, are negatively correlated with the efficiency of off-target effect. Analysis of experimentally validated miRNA targets demonstrated a similar trend, indicating a putative conserved mechanistic feature of seed region-dependent targeting mechanism. These observations may prove useful as parameters for off-target prediction algorithms and improve siRNA 'specificity' design rules.
| S-EPMC4676691 | biostudies-literature