Drosophila melanogaster
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA279510 | ENA |
REPOSITORIES: ENA
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Project description:We applied ChIP-seq to map the chromosomal binding sites for two nucleosome remodeling complexes containing the ATPase ISWI, ACF and RSF, in Drosophila embryos. Employing a panel of polyclonal and monoclonal antibodies directed against their signature subunits, ACF1 and RSF1, robust profiles were obtained indicating that both remodelers co-occupied a large set of active promoters. For further validation we repeated the mapping using chromatin of mutant embryos that do not express ACF1 or RSF1. Surprisingly, the ChIP-seq profiles were unchanged, suggesting that they were not due to specific immunoprecipitation. Conservative analysis lists about 3000 chromosomal loci, mostly active promoters that are prone to non-specific enrichment in ChIP and give rise to ‘Phantom Peaks’. These peaks are not obtained with pre-immune serum and are not prominent in input chromatin. Examination of various ACF1 and RSF1 antibodies in Drosophila melanogaster embryos which are wildtype or mutant for the antibody targets.
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Project description:We applied ChIP-seq to map the chromosomal binding sites for two nucleosome remodeling complexes containing the ATPase ISWI, ACF and RSF, in Drosophila embryos. Employing a panel of polyclonal and monoclonal antibodies directed against their signature subunits, ACF1 and RSF1, robust profiles were obtained indicating that both remodelers co-occupied a large set of active promoters. For further validation we repeated the mapping using chromatin of mutant embryos that do not express ACF1 or RSF1. Surprisingly, the ChIP-seq profiles were unchanged, suggesting that they were not due to specific immunoprecipitation. Conservative analysis lists about 3000 chromosomal loci, mostly active promoters that are prone to non-specific enrichment in ChIP and give rise to ‘Phantom Peaks’. These peaks are not obtained with pre-immune serum and are not prominent in input chromatin.
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Project description:Rhabdoid tumors (RT) are rare and highly aggressive pediatric neoplasms. Their epigenetically-driven intertumoral heterogeneity is well described; however, the cellular origin of RT remains an enigma. Here, we established and characterized different genetically engineered mouse models driven under the control of distinct promoters and being active in early progenitor cell types with diverse embryonic onsets. From all models only Sox2-positive progenitor cells give rise to murine RT. Using single-cell analyses, we identified distinct cells of origin for the SHH and MYC subgroups of RT, rooting in early stages of embryogenesis. Intra- and extracranial MYC tumors harbor common genetic programs and potentially originate from fetal primordial germ cells (PGCs). Using PGC specific Smarcb1 knockout mouse models we validated that MYC RT originate from these progenitor cells. We uncovered an epigenetic imbalance in MYC tumors compared to PGCs being sustained by epigenetically-driven subpopulations. Importantly, treatments with the DNA demethylating agent decitabine successfully impaired tumor growth in vitro and in vivo.
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Project description:Rhabdoid tumors (RT) are rare and highly aggressive pediatric neoplasms. Their epigenetically-driven intertumoral heterogeneity is well described; however, the cellular origin of RT remains an enigma. Here, we established and characterized different genetically engineered mouse models driven under the control of distinct promoters and being active in early progenitor cell types with diverse embryonic onsets. From all models only Sox2-positive progenitor cells give rise to murine RT. Using single-cell analyses, we identified distinct cells of origin for the SHH and MYC subgroups of RT, rooting in early stages of embryogenesis. Intra- and extracranial MYC tumors harbor common genetic programs and potentially originate from fetal primordial germ cells (PGCs). Using PGC specific Smarcb1 knockout mouse models we validated that MYC RT originate from these progenitor cells. We uncovered an epigenetic imbalance in MYC tumors compared to PGCs being sustained by epigenetically-driven subpopulations. Importantly, treatments with the DNA demethylating agent decitabine successfully impaired tumor growth in vitro and in vivo.
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Project description:Experiments conducted on this tiling array are used to (1) validate the frozen gene sets of the current genome annotation, (2) improve the predicted gene structures by empirically determining UTRs and intron-exon boundaries, identifying missing upstream, internal, and downstream exons and alternative transcripts, (3) propose gene structure models in transcribed regions containing no predicted genes and (4) delineate transcriptionally active regions of the genome from intergenic, intronic and genic regions. Signal to background ratios were determined by first calling probes that fluoresced at intensities greater than 99% of the random probes’ signal intensities; therefore only 1% of fluorescing experimental probes should be false positives. We conducted two-color competitive hybridizations that measure differential expression from three replicates, each using RNA from independent biological extractions. Transcriptional active regions (TARs) were defined by stringing together overlapping probes showing fluorescence above a 1% false positive rate (FPR). Positive probes were joined into a TAR if they were adjacent (maxgap=0, no intermittent non-positive probe) and a TAR’s length had to be at least 45 bp (minrun=45, mid-point first positive probe to mid-point last positive probe, resulting in at least 3 adjacent positive probes for a TAR). Transcriptional active regions (TARs) were defined by stringing together overlapping probes showing fluorescence above a 1% false positive rate (FPR). The data analysis to measure differential expression of genes and of unannotated TARs was performed using the statistical software package R and Bioconductor with additions and modifications. The signal distributions across chips, samples and replicates were adjusted to be equal according to the mean fluorescence of the random probes on each array. All probes including random probes were quantile-normalized across replicates. Expression-level scores were assigned for each predicted gene based on the median log2 fluorescence over background intensity of probes falling within the exon boundaries.
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