Homo sapiens
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA198233 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:Most sarcomas have complex karyotype and are characterized by multiple chromosomal rearrangements. Moreover, sarcomas very frequently maintain their telomeres by recombination in the process called Alternative Lengthening of Telomeres (ALT) which enables their continuous growth and immortalization. Previously our group showed that orphan receptors bind specifically to the ALT telomeres and that their presence is important for the ALT mechanism. In these studies we focus on the function of orphan receptors at the telomeres and their contribution to telomeric recombination. We demonstrate that orphan receptors induce proximity of their binding sites in telomeric and genomic context and reveal novel aspects of ALT which are telomere-genome rearrangements which can underlie complexity of sarcomas. Our data perturb the dogma of telomere function in protecting the genome integrity. Here we show that in some cases telomeres may in fact drive genomic instability and chromosomal rearrangements by recombination with genomic sites. Characterization of TRF2 and orphan receptor NR2F/C2 binding sites in ALT (-) and ALT (+) cells.
2015-02-23 | E-GEOD-46237 | biostudies-arrayexpress
Project description:Most sarcomas have complex karyotype and are characterized by multiple chromosomal rearrangements. Moreover, sarcomas very frequently maintain their telomeres by recombination in the process called Alternative Lengthening of Telomeres (ALT) which enables their continuous growth and immortalization. Previously our group showed that orphan receptors bind specifically to the ALT telomeres and that their presence is important for the ALT mechanism. In these studies we focus on the function of orphan receptors at the telomeres and their contribution to telomeric recombination. We demonstrate that orphan receptors induce proximity of their binding sites in telomeric and genomic context and reveal novel aspects of ALT which are telomere-genome rearrangements which can underlie complexity of sarcomas. Our data perturb the dogma of telomere function in protecting the genome integrity. Here we show that in some cases telomeres may in fact drive genomic instability and chromosomal rearrangements by recombination with genomic sites.
2015-02-23 | GSE46237 | GEO
Project description:Alternative Lengthening of Telomeres (ALT) is an aberrant DNA recombination pathway which grants replicative immortality to approximately 10% of all cancers. Despite this high prevalence of ALT in cancer, the mechanism and genetics by which cells activate this pathway remain incompletely understood. A major challenge in dissecting the events that initiate ALT is the extremely low frequency of ALT induction in human cell systems. Guided by the genetic lesions that have been associated with ALT from cancer sequencing studies, we genetically engineered primary human pluripotent stem cells to deterministically induce ALT upon differentiation. Using this genetically defined system, we demonstrate that disruption of the p53 and Rb pathways in combination with ATRX loss-of-function is sufficient to induce all hallmarks of ALT and results in functional immortalization in a cell type-specific manner. We further demonstrate that ALT can be induced in the presence of telomerase, is neither dependent on telomere shortening nor crisis, but is rather driven by continuous telomere instability triggered by the induction of differentiation in ATRX-deficient stem cells.
2023-02-21 | GSE212809 | GEO
Project description:Telomere is a highly refined system for maintaining the stability of linear chromosomes. Most telomeres rely on simple repetitive sequences and telomerase enzymes, but in some species or telomerase-defective situations, alternative telomere lengthening (ALT) mechanism is utilized to protect chromosomal ends. Telomere loss can induce telomere recombination by which specific sequences can be recruited into telomeres. However, canonical telomeric repeat-based telomeres have been found in mammals. Here, we show that mammalian telomeres can also be completely reconstituted using a non-telomeric unique sequence. We found that a specific subtelomeric element, named as mouse template for ALT (mTALT), is utilized for repairing telomeric DNA damage and composing new telomeric sequences in mouse embryonic stem cells. We found a high-level of non-coding mTALT transcript despite the heterochromatic nature of mTALT-based telomere. After ALT activation, the increased HMGN1, a non-histone chromosomal protein, contributed to maintaining telomere stability by regulating telomeric transcriptions. Our findings reveal novel molecular features of potential telomeric sequences which can reconstitute telomeres during cancer formation and evolution.
2020-07-17 | MSV000085772 | MassIVE
Project description:Telomere maintenance is indispensable for perpetuated cell division, but telomeres are not necessarily composed of a fixed sequence. Here we report the establishment of a model for alternative lengthening of telomeres (ALT) in mouse embryonic stem cells (mESCs) in which telomeres are reconstructed with an internal ALT template. Longitudinal whole-genome analyses of ALT mESCs showed that pre-amplification of the template into a telomeric region was a prerequisite for ALT activation, and that extensive copy number variations became concentrated in subtelomeric regions. Epigenomic analysis revealed the heterochromatic structure of the ALT telomeres, except for an insulator region within the ALT template. Quantitative proteomics followed by single-cell RNA-sequencing and functional assays revealed that HMGN1 protected new telomeres by regulating telomere repeat-containing RNA transcription and R loop formation in ALT mESCs. These findings implicate an evolutionarily conserved ALT mechanism driven by an internal template and provide a molecular basis underlying telomere evolution.
2020-12-30 | GSE147912 | GEO
Project description:Telomere attrition ultimately leads to the activation of protective cellular responses such as apoptosis or senescence. Impairment of such mechanisms can allow continued proliferation despite the presence of dysfunctional telomeres. Under such conditions, high levels of genome instability are often engendered. Data from both mouse and human model systems indicate that a period of genome instability might facilitate tumorigenesis. Here, we employ a liposarcoma model system to assay telomere maintenance mechanism-specific genetic alterations. A multiassay approach was used to assess the telomere maintenance mechanism(s) active in tumors. Genomic DNA from these samples was then analyzed by high resolution DNA mapping array in order to identify genetic alterations. Our data reveal a higher level of genome instability in ALT-positive tumors as compared with telomerase-positive tumors, whereas tumors lacking both mechanisms have relatively low levels of genome instability. The bulk of the genetic changes are amplifications, regardless of the mode of telomere maintenance employed. We also identified genetic changes specific to the ALT mechanism, e.g., deletion of chromosome 1q32.2-q44, as well as changes that are underrepresented amongst ALT-positive tumors, such as amplification of chromosome 12q14.3-q21.2. Taken together, these studies provide insight into the molecular pathways involved in the regulation of ALT and reveal several loci that might be exploited either as prognostic markers or targets of chemotherapeutic intervention. Keywords: genotype, genome instability, copy number alteration, liposarcoma, ALT, telomerase, telomere
2008-05-01 | GSE8046 | GEO
Project description:Telomeric repeat sequences are prone to induce replication stress and one of the core telomere binding proteins, TRF1, is thought to counteract these problems. The molecular mechanisms coming into play upon TRF1 loss were not clearly defined though. This study combines an inducible TRF1 loss with telomere-targeted proteomics to analyze the incurring changes. The results show that loss of TRF1 causes important alterations in telomere associated proteins and the new profile resembles in a number of ways that of cells in which telomeres are maintained by telomerase-independent mechanisms, named ALT. The presence of DNA repair proteins (MRN complex, the SMC5/6 complex), some increases in telomere colocalization with PML bodies, sister chromatid exchanges and clear signs of increased TERRA transcription and mitotic break-induced replication are part of these phenotypes. The data also show that these early ALT phenotypes can be differentiated from drug induced replication stress, and part of this ALT response is conserved in human cells. These studies therefore point to a critical role for TRF1 in preventing the emergence of ALT and hence immortalization of cells. Given that the details for how ALT actually is initiated remained unclear, these findings are an important step forward and will spur new research into that question.
2020-01-22 | PXD017022 | Pride
Project description:Telomere maintenance is indispensable for perpetuated cell division, but telomeres are not necessarily composed of a fixed sequence. Here we report the establishment of a model for alternative lengthening of telomeres (ALT) in mouse embryonic stem cells (mESCs) in which telomeres are reconstructed with an internal ALT template. Longitudinal whole-genome analyses of ALT mESCs showed that pre-amplification of the template into a telomeric region was a prerequisite for ALT activation, and that extensive copy number variations became concentrated in subtelomeric regions. Epigenomic analysis revealed the heterochromatic structure of the ALT telomeres, except for an insulator region within the ALT template. Quantitative proteomics followed by single-cell RNA-sequencing and functional assays revealed that HMGN1 protected new telomeres by regulating telomere repeat-containing RNA transcription and R loop formation in ALT mESCs. These findings implicate an evolutionarily conserved ALT mechanism driven by an internal template and provide a molecular basis underlying telomere evolution.
2020-12-30 | GSE160487 | GEO
Project description:Telomere maintenance is indispensable for perpetuated cell division, but telomeres are not necessarily composed of a fixed sequence. Here we report the establishment of a model for alternative lengthening of telomeres (ALT) in mouse embryonic stem cells (mESCs) in which telomeres are reconstructed with an internal ALT template. Longitudinal whole-genome analyses of ALT mESCs showed that pre-amplification of the template into a telomeric region was a prerequisite for ALT activation, and that extensive copy number variations became concentrated in subtelomeric regions. Epigenomic analysis revealed the heterochromatic structure of the ALT telomeres, except for an insulator region within the ALT template. Quantitative proteomics followed by single-cell RNA-sequencing and functional assays revealed that HMGN1 protected new telomeres by regulating telomere repeat-containing RNA transcription and R loop formation in ALT mESCs. These findings implicate an evolutionarily conserved ALT mechanism driven by an internal template and provide a molecular basis underlying telomere evolution.
2020-12-30 | GSE147914 | GEO
Project description:Telomere maintenance is indispensable for perpetuated cell division, but telomeres are not necessarily composed of a fixed sequence. Here we report the establishment of a model for alternative lengthening of telomeres (ALT) in mouse embryonic stem cells (mESCs) in which telomeres are reconstructed with an internal ALT template. Longitudinal whole-genome analyses of ALT mESCs showed that pre-amplification of the template into a telomeric region was a prerequisite for ALT activation, and that extensive copy number variations became concentrated in subtelomeric regions. Epigenomic analysis revealed the heterochromatic structure of the ALT telomeres, except for an insulator region within the ALT template. Quantitative proteomics followed by single-cell RNA-sequencing and functional assays revealed that HMGN1 protected new telomeres by regulating telomere repeat-containing RNA transcription and R loop formation in ALT mESCs. These findings implicate an evolutionarily conserved ALT mechanism driven by an internal template and provide a molecular basis underlying telomere evolution.
2020-12-30 | GSE147913 | GEO