Sequencing Apoptotic DNA Breakpoints
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE32997 | GEO | 2011/10/15
SECONDARY ACCESSION(S): PRJNA146515
REPOSITORIES: GEO
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Project description:DNA fragmentation is a well-recognized hallmark of apoptosis. However, the precise DNA sequences cleaved during apoptosis triggered by distinct mechanisms remain unclear. We used next-generation sequencing of DNA fragments generated in Actinomycin D-treated human HL-60 leukemic cells to generate a high-throughput, global map of apoptotic DNA breakpoints. These data highlighted that DNA breaks are non-random and show a significant association with active genes and open chromatin regions. We noted that transcription factor binding sites were also enriched within a fraction of the apoptotic breakpoints. Interestingly, extensive apoptotic cleavage was noted within genes that are frequently translocated in human cancers. We speculate that the non-random fragmentation of DNA during apoptosis may contribute to gene translocations and the development of human cancers. 3 files including 2 biological replicates (AHH001 and AHH002). Note that AHH002 is made up of 2 technical replicates (AHH002A and AHH002B)
2011-10-15 | E-GEOD-32997 | biostudies-arrayexpress
Project description:Balanced chromosome rearrangements (BCRs) can cause genetic diseases by disrupting or inactivating specific genes, and the characterisation of breakpoints in disease-associated BCRs has been instrumental in the molecular elucidation of a wide variety of genetic disorders. However, mapping chromosome breakpoints using traditional methods, such as in situ hybridization with fluorescent dye-labeled bacterial artificial chromosome clones (BAC-FISH), is rather laborious and time consuming. In addition, the resolution of BAC-FISH is often insufficient to unequivocally identify the disrupted gene. To overcome these limitations, we have performed shotgun sequencing of flow-sorted derivative chromosomes using ‘next generation’ (Solexa/Illumina) multiplex sequencing-by-synthesis technology. As shown here for three different disease-associated BCRs, the coverage attained by this platform is sufficient to bridge the breakpoints by PCR amplification, and this procedure allows to determine their exact nucleotide positions within few weeks. Its implementation will greatly facilitate large-scale breakpoint mapping and gene finding in patients with disease-associated balanced translocations. Keywords: Array CGH
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Project description:Balanced chromosome rearrangements (BCRs) can cause genetic diseases by disrupting or inactivating specific genes, and the characterisation of breakpoints in disease-associated BCRs has been instrumental in the molecular elucidation of a wide variety of genetic disorders. However, mapping chromosome breakpoints using traditional methods, such as in situ hybridization with fluorescent dye-labeled bacterial artificial chromosome clones (BAC-FISH), is rather laborious and time consuming. In addition, the resolution of BAC-FISH is often insufficient to unequivocally identify the disrupted gene. To overcome these limitations, we have performed shotgun sequencing of flow-sorted derivative chromosomes using ânext generationâ (Solexa/Illumina) multiplex sequencing-by-synthesis technology. As shown here for three different disease-associated BCRs, the coverage attained by this platform is sufficient to bridge the breakpoints by PCR amplification, and this procedure allows to determine their exact nucleotide positions within few weeks. Its implementation will greatly facilitate large-scale breakpoint mapping and gene finding in patients with disease-associated balanced translocations. Array CGH was performed in three carriers of balanced translocations to exclude DNA copy number changes.
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Project description:MiR-21 is an important suppressor of T-cell apoptosis that is also widely overexpressed in many types of cancers. The exact mechanisms related to the anti-apoptotic effect of miR-21 is not well understood. In this study, we applied AGO2 RNA Immunoprecipitation followed by gene expression profiling (RIP-Chip) in Jurkat cells to identify apoptosis-associated miR-21 target genes. We showed that expression of miR-21 rapidly increases upon αCD3/αCD28 activation of Jurkat cells. Inhibition of miR-21 resulted in reduced cell growth and induced apoptosis. Upon AGO2-RIP-Chip, we observed an overall increased enrichment of miR-21 target genes in the IP fraction of miR-21-overexpressing Jurkat cells as compared to the IP fraction of empty vector control cells. We noted a systematic decrease in transcript levels of predicted miR-21 target genes compared to EV control. We identified 72 genes that were 2-fold enriched in the AGO2-IP fraction of miR-21-overexpressing cells that contained a predicted miR-21 binding site. Of these, 71 were enriched 2-fold more in the miR-21-overexpressing cells as compared to EV Jurkat cells. The target gene for which the enrichment was most prominently increased upon miR-21 overexpression was the pro-apoptotic protein LATS1. Luciferase reporter assays confirmed direct targeting of the LATS1 3'UTR by miR-21. In line with the luciferase results, Western blot analysis revealed a decrease in LATS1 upon miR-21 inhibition. LATS1 qRT-PCR analysis in primary T-cells showed that LATS1 levels decrease upon T-cell stimulation while the miR-21 levels increase. Collectively, these data identify the miR-21 target LATS1 as a likely candidate whose inhibition contributes to the anti-apoptotic function of miR-21 in T-cells and perhaps also many types of cancers. Gene expression array on Jurkat cells overexpressing miR-21 and empty vector (EV).
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2010-06-05 | E-GEOD-619 | biostudies-arrayexpress
Project description:Previous studies showed that aging in coronary arteries is associated with pro-inflammatory phenotypic changes and decreased NO bioavailability, which, we hypothesized, promotes vascular disease by inducing endothelial apoptosis. To test this hypothesis we characterized pro-apoptotic alterations in the phenotype of coronary arteries of aged (26 month old) and young (3 month old) F344 rats. DNA fragmentation analysis and TUNEL assay showed that in aged vessels there was a ~4 fold increase in the number of apoptotic endothelial cells. Analysis of the expression of apoptosis-related genes (microarray, real-time PCR) showed that in aged coronary arteries there was an increased expression of TNFa, TNFb, caspase 9 and an increased presence of cleaved caspase 3 and caspase 9 (Western blotting), whereas expression of TNFR1 and that of TRADD, Bcl-2, Bcl-X(L), Bid, Bax, caspase 8 and caspase 3 were unchanged. We propose that aging-induced up-regulation of TNFa and decreased bioavailability of NO promote endothelial apoptosis in coronary arteries that may lead to the development of endothelial dysfunction and ischemic heart disease in the elderly. Keywords: repeat sample
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