Telomerase function and binding at endogenous G-rich regions (Hi-C Seq)
Ontology highlight
ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
PROVIDER: GSE143186 | GEO | 2020/01/07
REPOSITORIES: GEO
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Project description:Telomerase majorly functions at telomeres but under adverse conditions acts at endogenous regions, which is often observed in cancer calls. By mapping the global occupancy of the catalytic subunit of telomerase (Est2), we reveal that telomerase binds to multiple genomic loci, which we termed ‘non-telomere-binding sites’ (NTBS). We characterized under when and why Est2 binds to such sites and could show that telomerase is inactive but becomes activated upon global DNA damage. Indicating that those regions are of particular risk for genome stability. Using biochemical and molecular experiments we further characterized Est2 binding to NTBS. In contrast to Est2 binding to telomere neither Cdc13 nor Ku70/80 is crucial for the binding to NTBS. Strikingly, using Hi-C, we demonstrate that chromatin organization is essential and drives the interaction of Est2-NTBS binding. The here presented results provide a novel model of telomerase regulation using endogenous regions as “parking spots” awaiting its canonical function at telomeres.
2020-01-07 | GSE143184 | GEO
Project description:Telomeres are nucleoprotein complexes that protect the ends of eukaryotic chromosomes from being recognised as double strand breaks. When telomere structure is perturbed, a co-ordinated series of events to promote arrest of the cell cycle is rapidly initiated so that cells carrying damaged telomeres do not continue to divide. In order to better understand the eukaryotic response to telomere damage, we employed budding yeast strains harbouring a temperature sensitive allele of an essential telomere capping gene (cdc13-1) and conducted a transcriptomic study of the genome-wide response to uncapped telomeres. We show that telomere uncapping in cdc13-1 strains is associated with the differential expression of over 1100 genes and has features in common with the responses to DNA damage, diverse environmental stresses and, as expected, the absence of telomerase. The transcriptomic response to telomere uncapping includes many genes with known roles in telomere function and some features that appear to be unique. BNA2 is the second most highly up-regulated gene upon telomere uncapping in cdc13-1 strains and is required for the biosynthesis of NAD+. We have shown that deletion of BNA2 and other genes involved in NAD+ synthesis, suppresses the temperature sensitivity of cdc13-1 strains. NAD+ synthetic genes may therefore play previously unknown roles in the cellular response to telomere uncapping.
2010-02-24 | E-MEXP-1551 | biostudies-arrayexpress
Project description:Accumulating evidence suggests important roles of RNAs interacting with genomic regions in the regulation of genome functions including X chromosome inactivation and gene expression. However, no method to identify RNAs interacting with a given genomic region in a non-biased manner has been reported. Here, we used engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) combined with the RNA-Seq analysis (enChIP-RNA-Seq) to perform non-biased search of RNAs interacting with telomeres. In enChIP-RNA-Seq, the target genomic regions are captured with an engineered DNA-binding molecule such as a TAL protein. Subsequently, RNAs are purified and subjected to the RNA-Seq analysis. The detected RNAs contained known telomere-binding RNAs including telomerase RNA and Cajal body-specific RNAs. In addition, we detected many novel telomere-binding RNAs. We confirmed binding of candidate RNAs to telomeres by the enChIP-RT-PCR analysis. Identified novel telomere-binding RNAs may play important roles in telomere functions. In addition, our results suggest that enChIP-RNA-Seq analysis would be useful for identification of RNAs interacting with specific genomic regions. RNAs associated with telomeres were identified by using the enChIP technology combined with deep sequencing using Illumina Miseq. Briefly, to isolate telomeres, a TAL protein, Telomere-TAL (Tel-TAL), recognizing a 19-bp sequence containing an array of TTAGGG (telomere repeats) was fused with 3xFLAG tag and NLS (3xFN-Tel-TAL) and LexA protein (3xFNLDD)11 were expressed in a mouse hematopoietic cell line, Ba/F3, respectively. The cells were crosslinked with formaldehyde, and crosslinked chromatin was fragmented by sonication. Subsequently, chromatin complexes containing 3xFN-Tel-TAL or 3xFNLDD were immunoprepicitated with anti-FLAG M2 Ab. Supplementary URL: http://www.nature.com/srep/2013/131108/srep03171/full/srep03171.html
2015-04-16 | E-GEOD-60425 | biostudies-arrayexpress
Project description:Telomere homeostasis, crucial for various biological processes, relies on telomerase activity. We identified ZC3H15 as a novel telomerase-interacting protein. Its deletion unexpectedly increased telomerase activity but led to shortened telomeres and cellular senescence. ZC3H15 interacts with telomerase and itself, regulating telomerase activity in an RNA-dependent manner. Proximity labeling showed ZC3H15's interaction with proteins involved in organelle assembly and RNA processes. Loss of ZC3H15 sequestered TERC in the Cajal body, reducing telomerase recruitment to telomeres during S phase. These findings unveil ZC3H15's role in telomere dynamics and cellular senescence, suggesting its potential as a target for cancer therapy or anti-aging interventions.
2024-05-06 | PXD052036 |
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:RAP1 is one of the components of mammalian shelterin, the capping complex at chromosome ends or telomeres, although its role in telomere protection has remained elusive. RAP1 binds along chromosome arms, where it regulates gene expression and has been shown to function in metabolism control. Telomerase is the enzyme that elongates telomeres and its deficiency causes a premature aging in mice. We describe an unanticipated genetic interaction between RAP1 and telomerase. While RAP1 deficiency alone does not impact in mouse survival, mice lacking both RAP1 and telomerase show a progressive decreased survival with increasing mouse generation as compared to telomerase single mutants. Telomere shortening was more pronounced in Rap1-/- Terc-/- than in Terc-/- counterparts, leading to an earlier onset of DNA damage and its consequent DNA damage response as well as accelerated degenerative pathologies in the intestines. In its turn, telomerase deficiency abolishes RAP1-mediated obesity and liver pathologies. Mouse embryonic fibroblasts with shorten telomeres present less amount of telomere-bound RAP1 but in contrast show higher numbers of RAP1 bound extratelomeric sites genomewide. Absence of RAP1 leads to deregulation of several metabolic pathways, and these changes were more pronounce in cells with short telomeres suggesting that RAP1 release from telomere foci could constitute a coordinated genomic response to telomere shortening. Our findings also demonstrate that although RAP1 is not a key factor in telomere capping under normal conditios, under stress situation such as critical telomere shortening RAP1 exerts an important function for telomere protection and justify its evolutionary conservation as a shelterin component in mammalian cells.
2016-11-16 | GSE79996 | GEO
Project description:Accumulating evidence suggests important roles of RNAs interacting with genomic regions in the regulation of genome functions including X chromosome inactivation and gene expression. However, no method to identify RNAs interacting with a given genomic region in a non-biased manner has been reported. Here, we used engineered DNA-binding molecule-mediated chromatin immunoprecipitation (enChIP) combined with the RNA-Seq analysis (enChIP-RNA-Seq) to perform non-biased search of RNAs interacting with telomeres. In enChIP-RNA-Seq, the target genomic regions are captured with an engineered DNA-binding molecule such as a TAL protein. Subsequently, RNAs are purified and subjected to the RNA-Seq analysis. The detected RNAs contained known telomere-binding RNAs including telomerase RNA and Cajal body-specific RNAs. In addition, we detected many novel telomere-binding RNAs. We confirmed binding of candidate RNAs to telomeres by the enChIP-RT-PCR analysis. Identified novel telomere-binding RNAs may play important roles in telomere functions. In addition, our results suggest that enChIP-RNA-Seq analysis would be useful for identification of RNAs interacting with specific genomic regions.
2015-04-16 | GSE60425 | GEO
Project description:Limitless reproductive potential is one of the hallmarks of cancer cells1. This ability is accomplished by maintaining telomeres, which erosion otherwise causes cellular senescence or death. Human cancer cells often maintain shorter telomeres than do cells in surrounding normal tissues2-5. While most cancer cells activate telomerase, which can elongate telomeres6, it remains elusive why cancer cells keep telomeres short. Here we show that forced elongation of telomeres in cancer cells promotes their differentiation in a tumor microenvironment in vivo. We elongated telomeres of human prostate cancer PC-3 cells, which possess short telomeres7, by enhancing their telomerase activity. The resulting cells with long telomeres retain an ability to form tumors in a mouse xenograft model. Strikingly, these tumors exhibit many duct-like structures and reduced N-cadherin expression, reminiscent of well-differentiated adenocarcinoma. These phenotypic changes are caused by telomere elongation per se but not enhanced telomerase activity. Gene expression profiling revealed that telomere elongation correlates with inhibition of cell-cycle processes. Together, our results suggest a functional contribution of short telomeres to tumor malignancy by regulating cancer cell differentiation. Two samples are telomere-elongated cells, both in the presence and absence of the exogenous hTERT. The other two samples are control cell lines.
2013-05-31 | E-GEOD-36649 | biostudies-arrayexpress
Project description:At critically short telomeres TERRA RNA-DNA hybrids become stabilized and drive homology-directed repair (HDR) to delay replicative senescence. However, even at long- and intermediate-length telomeres, not subject to HDR, transient TERRA RNA-DNA hybrids form, suggestive of additional roles. Here, we report that hybrids at telomeres prevent resection by the Exo1 nuclease when telomeres become non-functional. We employed the well-characterized cdc13-1 allele, where telomere resection can be induced in a temperature dependent manner, to demonstrate that ssDNA generation at telomeres is either prevented or augmented when RNA-DNA hybrids are stabilized or destabilized, respectively. The viability of cdc13-1 cells is affected by the presence or absence of hybrids accordingly. These results give insights into an additional role of TERRA at dysfunctional telomeres suggesting that it not only affects replicative senescence rates through HDR activation at critically short telomeres, but may also affect resection rates at intermediate length telomeres in pre-senescent cells.
2023-01-18 | PXD034986 | Pride
Project description:Limitless reproductive potential is one of the hallmarks of cancer cells1. This ability is accomplished by maintaining telomeres, which erosion otherwise causes cellular senescence or death. Human cancer cells often maintain shorter telomeres than do cells in surrounding normal tissues2-5. While most cancer cells activate telomerase, which can elongate telomeres6, it remains elusive why cancer cells keep telomeres short. Here we show that forced elongation of telomeres in cancer cells promotes their differentiation in a tumor microenvironment in vivo. We elongated telomeres of human prostate cancer PC-3 cells, which possess short telomeres7, by enhancing their telomerase activity. The resulting cells with long telomeres retain an ability to form tumors in a mouse xenograft model. Strikingly, these tumors exhibit many duct-like structures and reduced N-cadherin expression, reminiscent of well-differentiated adenocarcinoma. These phenotypic changes are caused by telomere elongation per se but not enhanced telomerase activity. Gene expression profiling revealed that telomere elongation correlates with inhibition of cell-cycle processes. Together, our results suggest a functional contribution of short telomeres to tumor malignancy by regulating cancer cell differentiation. Two cell lines are telomere-elongated cells, both in the presence and absence of the exogenous hTERT. The other two lines are control PC-3 cell lines. We extracted RNA from four independent xenograft tumors per original cell line.
2013-05-31 | E-GEOD-41559 | biostudies-arrayexpress