Target Specificity of Epigenetic Therapy
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA312618 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:This SuperSeries is composed of the SubSeries listed below.
2017-02-08 | GSE78110 | GEO
Project description:Regulation of specific target genes by transcription factors is central to gene network control in development. How target specificity is achieved in eukaryotic genomes is poorly understood, as exemplified by the Hox family, which show limited in vitro DNA-binding specificity but clear functional specificity in vivo. We generated genome-wide binding profiles for three Hox proteins, Ubx, Abd-A and Abd-B, in Drosophila Kc167 cells, revealing clear target specificity and a striking influence of chromatin accessibility. Ubx and Abd-A bind to similar target sites in accessible chromatin whereas Abd-B binds additional specific targets. Provision of the TALE class cofactors, Exd and Hth, alters the Ubx binding profile, enabling binding to additional targets in the genome. Both the Abd-B specific targets and the cofactor-dependent Ubx targets are in relatively DNase1 inaccessible chromatin, suggesting that competition with nucleosomes is a key factor determining Hox protein target specificity. This ChIP-Seq study performed on Kc167 cells involves two experiments and 6 ChIP samples. In Experiment 1, we generated genome-wide binding profiles for Ubx, Abd-A and Abd-B. An equal volume of input chromatin was retained from each of the Hox samples and combined to represent the input, which was purified alongside the ChIP samples. We performed two biological replicates for each sample. Sequencing was performed using the Illumina MiSeq platform. In Experiment 2, we generated genome-wide binding profiles for Ubx, mutant Ubx and Ubx in the presence of Hth. We performed two biological replicates for each sample except Ubx where we performed just one. Sequencing was performed using the Illumina HiSeq 2000 platform. For all samples, Experiment 1 input chromatin was used as the reference control to assay ChIP enrichment.
2015-12-07 | E-GEOD-69796 | biostudies-arrayexpress
Project description:Regulation of specific target genes by transcription factors is central to gene network control in development. How target specificity is achieved in eukaryotic genomes is poorly understood, as exemplified by the Hox family, which show limited in vitro DNA-binding specificity but clear functional specificity in vivo. We generated genome-wide binding profiles for three Hox proteins, Ubx, Abd-A and Abd-B, in Drosophila Kc167 cells, revealing clear target specificity and a striking influence of chromatin accessibility. Ubx and Abd-A bind to similar target sites in accessible chromatin whereas Abd-B binds additional specific targets. Provision of the TALE class cofactors, Exd and Hth, alters the Ubx binding profile, enabling binding to additional targets in the genome. Both the Abd-B specific targets and the cofactor-dependent Ubx targets are in relatively DNase1 inaccessible chromatin, suggesting that competition with nucleosomes is a key factor determining Hox protein target specificity.
2015-12-07 | GSE69796 | GEO
Project description:To study target sequence specificity, selectivity, and reaction kinetics of Streptococcus pyogenes Cas9 activity, we challenged libraries of random variant targets with purified Cas9::guide RNA complexes in vitro. Cleavage kinetics were nonlinear, with a burst of initial activity followed by slower sustained cleavage. Consistent with other recent analyses of Cas9 sequence specificity, we observe considerable (albeit incomplete) impairment of cleavage for targets mutated in the PAM sequence or in "seed" sequences matching the proximal 8 bp of the guide. A second target region requiring close homology was located at the other end of the guide::target duplex (positions 13-18 relative to the PAM). Strikingly, a subset of variants which broke homology in the intervening region consistently increased the capacity of Cas9 to cleave in extended reactions. Sequences flanking the guide+PAM region had measurable (albeit modest) effects on cleavage. Taken together, these studies provide both a basis for predicting effective cleavage targets and a basis for potential optimization of guide RNAs to yield efficiency beyond that of the simple perfect-match guides.
2014-11-14 | GSE58426 | GEO
Project description:Cancer-specific coding mutations can create neoantigens that can be presented on the cell surface of tumors to trigger immunogenic clearance1–4. However, current cancer vaccine approaches have not been universally effective5; this is especially true in tumors with a low mutational burden which, in turn, carry a low conventional neoantigen load6. Transposable elements (TEs) make up approximately 50% of the human genome and have been discovered to provide cryptic promoters, which can be reactivated with epigenetic manipulations to generate TE-gene chimeric transcripts that can be translated into noncanonical peptides7. Here, we focus on glioblastoma, an aggressive brain cancer with low mutation burden, to explore whether epigenetic therapy can induce TE-chimeric antigens (TEAs) to appreciably increase the antigen repertoire that can be targeted with immunotherapy. We perform comprehensive epigenetic and transcriptomic profiling of three patient-derived glioblastoma stem cell lines (GSCs) and, more importantly, astrocyte and fibroblast primary cell lines that are either proliferating or quiescent, treated with epigenetic therapy drugs to identify treatment-induced TEA (TI-TEA) candidates that are preferentially expressed in cancer cells. Although we verify TI-TEAs are indeed presented on HLA molecules in GSCs thus are promising cancer vaccine candidates, many TEs were also transcriptionally activated in proliferating primary cell lines after epigenetic therapy. This work presents a cautionary but optimistic tale for future efforts in harnessing TI-TEAs for targeted immunotherapy approaches.
2024-06-05 | PXD039893 | Pride
Project description:To study target sequence specificity, selectivity, and reaction kinetics of Streptococcus pyogenes Cas9 activity, we challenged libraries of random variant targets with purified Cas9::guide RNA complexes in vitro. Cleavage kinetics were nonlinear, with a burst of initial activity followed by slower sustained cleavage. Consistent with other recent analyses of Cas9 sequence specificity, we observe considerable (albeit incomplete) impairment of cleavage for targets mutated in the PAM sequence or in "seed" sequences matching the proximal 8 bp of the guide. A second target region requiring close homology was located at the other end of the guide::target duplex (positions 13-18 relative to the PAM). Strikingly, a subset of variants which broke homology in the intervening region consistently increased the capacity of Cas9 to cleave in extended reactions. Sequences flanking the guide+PAM region had measurable (albeit modest) effects on cleavage. Taken together, these studies provide both a basis for predicting effective cleavage targets and a basis for potential optimization of guide RNAs to yield efficiency beyond that of the simple perfect-match guides. 118 samples anaylzed. Controls have con in sample name. To quantitatively measure cleavage efficiency of a single gRNA, we created a population of random variant target sequences to two gRNA targets. The targets used were "unc-22A", [a sequence from the well-characterized unc-22 gene of Caenorhabditis elegans], and "protospacer 4" (ps4), a previously characterized sequence from a natural spacer from S. pyogenes MGAS10750 . Using custom mixtures of oligonucleotide precursors for each base during chemical synthesis, a set of polymorphic target libraries ('Random Variant Libraries') were designed to have a baseline variation rate at each position. On each side of the gRNA homology and PAM regions, 6 bps of random sequence were added. The first base of intended gRNA homology is designated base 1 . The entire 35 bp random variant library mixture was cloned into a standard plasmid vector (pHRL-TK). Several thousand colonies from plates were washed in pools and prepared by standard plasmid preparation methods. The complexity of the libraries were estimated based on Illumina sequencing of the uncut libraries and filtering for minimum representation expected from the pooling. Approximately 1500-3000 unique species were obtained in the unc-22A libraries and 5000 unique sequences in the ps4 library (see Materials and Methods). To assay cleavage, purified Cas9 was first incubated with gRNA, followed by incubation with the variant library for various time points and under various conditions. DNA template is among the conditions varied in the experiments. After protein removal, flanking sequences outside of the target region are used for PCR amplification and plasmid cleavage was measured through loss of PCR products that span the region of interest. A set of perfectly matched targets and highly mutated versions present in the random variant library served as internal positive and negative controls respectively. A log retention score for each sequence in each experiment was calculated by quantifying the representation of each sequence before and after addition of the Cas9 protein. Two approaches were used for normalization: first we used a population of ps4 targets "spiked" into the library as an uncleaved control, second, we used a population of unc-22A targets with large numbers of variations from the perfect target (between 4 and 7), and hence likely limited if any cleavage. Equivalent results are obtained with these two normalization approaches (see Computational Methods for details). Retention scores are expressed as the log2 of the normalized ratio, so that a more negative retention score indicates efficient cleavage of substrate while a less negative score indicates less cleavage. Templates which are uncleaved will yield a retention score at or near zero. Comparisons between multiple experiments indicate strong correlation between independent retention measurements. GSM1410678-GSM1410761; AF_SOL*.dat' files contain the calculated final retentions for each experiment. Each experiment labeled: M-bM-^@M-^\AF_SOL_###_t###M-bM-^@M-^]. M-bM-^@M-^\AF_SOL_###M-bM-^@M-^] corresponds to the experiment run ID and M-bM-^@M-^\t###M-bM-^@M-^] corresponds to the incubation time of the experiment. For example AF_SOL_513_t360, corresponds to experiment 513 on the protospacer 4 guide and DNA target and the incubation time was 360 mins. The experimental conditions and ID can be found in the associated publication. GSM1544297-GSM1544332; unc*.dat file is a tab-delimited file of all considered sequences in each experiment. The names of the files and the AF_SOL_# run number can be found in the associated publication (Supplementary Materials) with the details of the conditions. Each filename starts with the type of gRNA used (either unc-22WT or the mutant version unc22C11G). The next number (#min) is indication of the time of incubation for the experiment and this is either followed by #pcr_AF_SOL_# or just AF_SOL_#. If followed by #pcr, that is the indication of the number of PCR cycles used in the experiments. Finally, AF_SOL_# denotes the sequencing run ID number.
2014-11-14 | E-GEOD-58426 | biostudies-arrayexpress
Project description:Here we investigate the impact of epigenetic therapy with Decitabine in endocrine-resistant ER+ breast cancer by using patient-derived xenograft (PDX) models. Decitabine treatment restrained tumour growth, inhibited cell proliferation and resulted in significant loss of DNA methylation, particularly at enhancers and repetitive elements. Systematic integration of matched in situ Hi-C / PCHi-C, EPIC, RNA-seq and ChIP–seq datasets revealed widespread differences in epigenome regulation and enhancer-promoter communication with Decitabine. We find that loss of DNA methylation with Decitabine strongly affects the open (A) and closed (B) compartment structure and TAD boundary insulation. Our study identified and focused on key DNA methylation-dependent, enhancer ER binding sites that are activated in Decitabine-treated PDX tumours, enabling direct interactions between promoters and multiple distal enhancers, inducing expression of ER target genes and pathways. Overall, we demonstrate that epigenetic therapy inhibits tumour progression through to rewiring of ER-mediated 3D chromatin interactions and transcriptome programs. Our findings suggest that targeting the 3D epigenome with epigenetic therapies represents a promising strategy for anti-cancer treatment in ER+ endocrine resistant breast cancer patients.
2023-07-24 | GSE237769 | GEO
Project description:Cas9, a CRISPR RNA-guided nuclease, has been rapidly adopted as a tool for biochemical and genetic manipulation of DNA. Although Cas9 offers remarkable specificity and versatility for genome manipulation, mis-targeted events occur. To extend the understanding of Cas9 target::homology requirements, we compared mismatch tolerance for a specific Cas9::gRNA complex in vitro and in vivo (in Saccharomyces cerevisiae). A variety of truncated and full-length gRNAs (with 17, 18, and 20 nucleotides of complementarity sequence) were used. In each case, we observed notable differences between in vitro and in vivo Cas9 cleavage specificity profiles, with a more stringent effect of mismatches on activity seen in vivo. Increased specificity of the 18 nt complementarity truncated gRNA was evident in vivo, but not in vitro. Overall, this study highlights differences in the specificity of Cas9 cleavage between controlled in vitro conditions and complex and chromatinized in vivo conditions.
2016-06-10 | GSE79667 | GEO
Project description:HDAC6-LINC00461 pathway as a potential target for glioblastoma therapy
| PRJNA755321 | ENA
Project description:Cas9, a CRISPR RNA-guided nuclease, has been rapidly adopted as a tool for biochemical and genetic manipulation of DNA. Although Cas9 offers remarkable specificity and versatility for genome manipulation, mis-targeted events occur. To extend the understanding of Cas9 target::homology requirements, we compared mismatch tolerance for a specific Cas9::gRNA complex in vitro and in vivo (in Saccharomyces cerevisiae). A variety of truncated and full-length gRNAs (with 17, 18, and 20 nucleotides of complementarity sequence) were used. In each case, we observed notable differences between in vitro and in vivo Cas9 cleavage specificity profiles, with a more stringent effect of mismatches on activity seen in vivo. Increased specificity of the 18 nt complementarity truncated gRNA was evident in vivo, but not in vitro. Overall, this study highlights differences in the specificity of Cas9 cleavage between controlled in vitro conditions and complex and chromatinized in vivo conditions. We adapted a previous high throughput sequencing approach (doi: 10.1093/nar/gku1102) to assess the effects of single base variants in vivo. We used a polymorphic random variant library matched to a specific trigger sequence (for which we used a segment from the C. elegans unc-22 gene, previously designated âunc-22Aâ (doi: 10.1093/nar/gku1102). Cas9 in vivo and in vitro assays were carried out with four different gRNAs incorporating sequence from the unc-22A trigger segment. The four segments incorporate 17 nt, 18 nt, 20 nt, and 20+G nt of unc-22A complementarity respectively. The retention is calculated based on PMID: 25399416. File names denote the experiment-> gRNAname_gRNAlength_(invitro or invivo)_(incubation or induction time)_IlluminaRunID.dat The files contain all normalized sequences in column one with their calculated retentions in column 2.
2016-06-10 | E-GEOD-79667 | biostudies-arrayexpress