The Complex Architecture of Transgene Insertions
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA427134 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR6409890_1.fastq.gz | Fastqsanger.gz | |||
| SRR6409890_2.fastq.gz | Fastqsanger.gz | |||
| SRR6409891_1.fastq.gz | Fastqsanger.gz | |||
| SRR6409891_2.fastq.gz | Fastqsanger.gz | |||
| SRR6409892_1.fastq.gz | Fastqsanger.gz |
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Project description:Over the last 30 years the soil bacterium Agrobacterium tumefaciens has been the workhorse tool for plant genome engineering. Replacement of native tumor-inducing (Ti) plasmid elements with customizable cassettes enabled insertion of a sequence of interest as “Transfer DNA” (T-DNA) into the plant genome of interest. Although these T-DNA transfer mechanisms are well understood, detailed understanding of the structure and epigenomic status of insertion events was limited by current technologies. To fill this gap, we analyzed transgenic Arabidopsis thaliana lines from three widely used collections (SALK, SAIL and WISC) with two single molecule technologies, optical genome mapping and nanopore sequencing. Optical maps for four randomly selected T-DNA lines revealed between one and seven insertions/rearrangements with unexpectedly large sizes ranging from 27 to 236 kilobases. De novo nanopore-based genome assemblies for two heterozygous lines resolved T-DNA structures up to 36 kb and revealed large-scale T-DNA associated translocations and exchange of chromosome arm ends. The multiple internally rearranged nature of T-DNA arrays, consisting of identical T-DNA/backbone concatemers made full assembly even for long nanopore reads impossible. For the current TAIR10 reference genome, nanopore contigs corrected 83% of non-centromeric misassemblies. This unprecedented nucleotide-level definition of T-DNA insertions enabled the mapping of epigenome data. The SALK_059379 T-DNA insertions were enriched for 24nt siRNAs and contained dense cytosine DNA methylation. Transgene silencing via the RNA directed DNA methylation pathway was confirmed by in planta assays. In contrast, SAIL_232 T-DNA sequence was predominantly targeted by 21/22nt siRNAs, and DNA methylation and silencing was limited to the GUS gene, but not the resistance gene. With the emergence of genome editing technologies that rely on Agrobacterium for gene delivery, this study provides new insights into the structural impact of engineering plant genomes and demonstrates the utility of state-of-the-art long-range sequencing technologies to rapidly identify unanticipated genomic changes.
2018-03-16 | GSE108401 | GEO
Project description:The integration of T-DNA to plant genomes is widely used for basic research and agriculture. High heterogeneity in the number of integration events per genome, their configuration and impact on genome integrity highlight both, the critical need and great challenge to detect the genomic locations of T-DNA insertions and their associated chromosomal rearrangements. Here we present ‘4SEE’, a circular chromosome conformation capture (4C) based method for robust, rapid and cost-efficient detection of the entire scope T-DNA locations. Moreover, by measuring the chromosomal architecture at plant genome flanking the T-DNA insertions, 4SEE outlines their associated complex chromosomal aberrations. Applying 4SEE to a collection of confirmed T-DNA lines revealed previously unmapped T-DNA insertions and chromosomal rearrangements such as inversions and translocations. Uncovering such events in feasible, robust and cost-effective manners by 4SEE in any plant of interest have implications for accurate annotation and phenotypic characterization of T-DNA insertion mutants and transgene expression in basic science applications as well as for plant biotechnology.
2020-04-05 | GSE147542 | GEO
Project description:The position and complex genomic architecture of plant T-DNA insertions revealed by 4C
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Project description:We identified 16 individuals with complex insertions among 56,000 individuals tested at Baylor Genetics Laboratories using clinical array comparative genomic hybridization (aCGH) and fluorescence in situ hybridization (FISH). Custom high-density aCGH was performed on individuals with available DNA, and breakpoint junctions were fine-mapped at nucleotide resolution by long-range PCR and DNA sequencing to glean insights into potential mechanisms of formation.
2016-10-30 | GSE89306 | GEO
Project description:A reporter transgene displayed parental imprinting in mouse embryos when positioned into the Itga6 gene. The strong lacZ pattern of expression scored in embryos inheriting the transgene from a male was not present when transmitted from a female. The transgene exhibited maternal allele-specific DNA hyper-methylation acquired in the germ-line and histone modifications corresponded to profiles described at known imprinted loci. Chromosome conformation analyzes revealed distinct, parent-of-origin interaction domains, with a more compact structure characterizing the maternally inherited repressed allele. The analysis of such transgene insertions with a selective potential to induce imprinting may help understanding the mechanisms identifying particular loci as targets for allele-specific repression.
2013-07-03 | GSE48148 | GEO
Project description:Insertions occur when a segment of one chromosome is translocated and inserted into a new region of the same chromosome or a non-homologous chromosome. We report 69 cases with unbalanced insertions identified using array CGH and FISH, representing 1.25% of 5,683 cases referred to our laboratory for array CGH and found to have copy-number abnormalities. Although the majority of insertions were non-recurrent, several recurrent unbalanced insertions were detected, including three der(Y)ins(Y;18)(q?11.2;p11.32p11.32)pat inherited from parents carrying an unbalanced insertion. The clinical significance of these recurrent rearrangements is unclear, although the small size, limited gene content, and inheritance pattern of each suggests the phenotypic consequences may be benign. Moreover, cryptic, submicroscopic duplications were observed at or near the insertion sites in two patients, further confounding the clinical interpretation of these insertions. Using FISH, linear amplification and array CGH we identified a 126-kb duplicated region from 19p13.3 inserted into MECP2 at Xq28 in a patient with symptoms of Rett syndrome. Our results demonstrate that although the interpretation of most non-recurrent insertions is unclear without high-resolution insertion site characterization, the potential for an otherwise benign duplication to result in a clinically relevant outcome through the disruption of a gene necessitates the use of FISH to determine whether copy-number gains detected by array CGH represent tandem duplications or unbalanced insertions. Further follow-up testing using techniques such as linear amplification coupled with array CGH or sequencing should be used to determine gene involvement at the insertion site after FISH has identified the presence of an insertion.
2011-02-28 | GSE27080 | GEO
Project description:Formation of templated insertions at DNA double-strand breaks (DSBs) is very common in cancer cells. The mechanisms and enzymes regulating these events are largely unknown. Here, we investigated templated insertions in yeast at DSBs using amplicon sequencing across a repaired locus. We document very short (most ~5-34 bp), templated inverted duplications at DSBs. They are generated through a foldback mechanism that utilizes microhomologies adjacent to the DSB. Enzymatic requirements suggest a hybrid mechanism wherein one end requires Polδ-mediated synthesis while the other end is captured by nonhomologous end joining (NHEJ) or rarely by alternative end joining (Alt-EJ). This process is exacerbated in mutants with low levels or mutated RPA (rtt105Δ; rfa1-t33) or extensive resection mutant (sgs1Δ exo1Δ). Templated insertions from various distant genomic locations also increase in these mutants as well as in rad27 and originate from fragile regions of the genome. Among complex insertions, common events are insertions of two sequences, originating from the same locus and with inverted orientation. We propose that these inversions are also formed by microhomology-mediated template switching. Taken together, we propose that a shortage of RPA typical in cancer cells is one possible factor stimulating the formation of templated insertions.
2024-03-07 | GSE260753 | GEO
Project description:The noncoding regions of tumor cell genomes harbor a considerable fraction of total variation, but the functional contribution of such variants to tumorigenesis is ill-defined. Among these noncoding variants, somatic insertions are among the least well-characterized due to challenges with interpreting short-read DNA sequences. To address this, we have identified enhancer-associated small insertion variants across a spectrum of tumor cells by using ChIP-seq to enrich and sequence enhancer DNA, and a computational approach with multiple alignment procedures to identify small insertions. Among the 82 tumor genomes studied here, small insertions were frequently observed in enhancer DNA sequences located near known oncogenes. Further study of one such insertion, found in primary leukemia tumor genomes, revealed that it nucleates formation of an active enhancer that drives expression of the LMO2 oncogene. The catalogue of enhancer-associated small insertion variants described here provides a foundation for further investigating the functions of this class of variants across a range of human cancers.
2016-07-08 | GSE76783 | GEO
Project description:Insertions and deletions (indels) are common sources of structural variation, and insertions originating from spontaneous DNA lesions are frequent in cancer. We developed a highly sensitive assay (Indel-Seq) to monitor rearrangements in human cells at the TRIM37 acceptor locus that reports indels stemming from experimentallyinduced and spontaneous genome instability. Templated insertions, which derive from sequences genome-wide, require contact between donor and acceptor loci, homologous recombination, and are stimulated by DNA end-processing. Insertions are facilitated by transcription and involve a DNA/RNA hybrid intermediate. Indel-Seq reveals that insertions are generated via multiple pathways. The broken acceptor site anneals with a resected DNA break or invades the displaced strand of a transcription bubble or R-loop followed by DNA synthesis, displacement and then ligation by nonhomologous end-joining. Our studies identify transcription-coupled insertions as a critical source of spontaneous genome instability that are distinct from cut-and-paste events
2023-07-03 | GSE234089 | GEO
Project description:How is chromatin architecture established and what role does it play in activation of transcription? We show that a regulatory locus in yeast (the UASg) bears, in addition to binding sites for the activator Gal4, sites bound by the protein RSC. RSC tightly positions a nucleosome, evidently partially unwound, in a structure that facilitates Gal4 binding to its sites. The complex comprises a barrier that suffices to impose characteristic features of chromatin architecture. Removal of RSC allows ordinary nucleosomes to form more broadly over the UASg, and these nucleosomes compete with (but do not exclude) Gal4 binding to its sites. Taken with our previous work, the results show that both prior to and following induction specific DNA binding proteins are the predominant determinants of chromatin architecture at the GAL1/10 genes. RSC/nucleosome complexes are found scattered throughout the yeast genome. We surmise, also, that Gal4 works in higher eukaryotes despite whatever obstacle broadly positioned nucleosomes present. Chromatin was digested under conditions that yielded primarily mononucleosomes, and RSC-bearing fragments were recovered on IgG-beads. Fragments (of size ca. 50-200 bp) were analyzed by paired-end high throughput DNA sequencing (Illumina). This technique determines the sequences found at both ends of each fragment, thus revealing the sizes and genomic origin of these fragments.
2010-05-01 | E-GEOD-20078 | biostudies-arrayexpress