Telomeres suppress the activity of retrotransposons in pluripotent stem cells [exp1]
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE100168 | GEO | 2022/12/25
REPOSITORIES: GEO
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Project description:Telomeres, which locate at the end of chromosomes protect chromosomes from fusion and deterioration. This is essential for cells to maintain genome staibility. We applied RNA-seq, to identify the impact of Terc knockout on the expression of retrotransposons in embryonic stem cells.
2019-12-31 | GSE118026 | GEO
Project description:We asked whether telomere shortening impairs differentiation of ESCs into germ cell lineage. Terc-/- ESCs were used to investigate the effects of short telomeres on germ cell specification by in vitro differentiation. Short telomeres greatly reduced induction of PGCLCs from ESCs. Mechanistically, short telomeres resulted in excessive chromatin accessibility, which in turn activated the genes regulated by chromatin. Notably, Fst overexpression reduced BMP-Smad signaling and thus induction of PGCLCs, meanwhile upregulation of MAPK signaling pathway increase somatic lineage differentiation in short telomeres sampels. Moreover, knockin of Terc gene by CRISPR/Cas9 in Terc-/- ESCs restored telomere length and normal gene expression profile, and rescued PGCLC induction, revealing important roles of telomeres in PGC fate decision.
2022-08-31 | GSE157303 | GEO
Project description:We asked whether telomere shortening impairs differentiation of ESCs into germ cell lineage. Terc-/- ESCs were used to investigate the effects of short telomeres on germ cell specification by in vitro differentiation. Short telomeres greatly reduced induction of PGCLCs from ESCs. Mechanistically, short telomeres resulted in excessive chromatin accessibility, which in turn activated the genes regulated by chromatin. Notably, Fst overexpression reduced BMP-Smad signaling and thus induction of PGCLCs, meanwhile upregulation of MAPK signaling pathway increase somatic lineage differentiation in short telomeres sampels. Moreover, knockin of Terc gene by CRISPR/Cas9 in Terc-/- ESCs restored telomere length and normal gene expression profile, and rescued PGCLC induction, revealing important roles of telomeres in PGC fate decision.
2022-08-31 | GSE157301 | GEO
Project description:Mammalian telomeres are formed by tandem repeats of the TTAGGG sequence, and shorten with each round of cell division in the absence of telomerase. Telomere shortening and dysfunction has been implicated in the pathology of several age-related diseases and premature ageing syndromes. Telomerase is important for telomere length maintenance. Telomerase RNA component, also known as TERC, is a component of telomerase. Terc knockout leads to telomerase deficiency and telomere shortening. Heterozygous telomerase-deficient (Terc+/-) mice were housed and bred for homozygous generation. ESC lines were generated with high efficiency from wild-type (WT, Terc+/+), heterozygous (Het, Terc+/-) and early- to late-generation (G1, G3 and G4) Terc-/- mouse blastocysts. Telomeres were shorter in Terc+/- ES cells than in WT ES cells, and further shortened from G1 to G4 Terc-/- ES cells. We took advantage of ES cell lines with various telomere lengths to investigate roles of telomere length on differentiation capacity of ES cells. We found that telomere length, but not telomerase activity, is required for differentiation of ES cells into epidermis. We performed microarray analysis to investigate differential gene expression profile at genome-wide levels between WT and G3/G4 Terc-/- (KO) mouse ES cells and during differentiation in vitro of WT and G4 Terc-/- mouse ES cells.
2016-01-29 | GSE77362 | GEO
Project description:Telomere shortening rates must be regulated to prevent premature replicative senescence. TERRA R-loops become stabilized at critically short telomeres to promote their elongation through homology-directed repair (HDR), thereby counteracting senescence onset. Using a non-bias proteomic approach to identify telomere binding factors, we identified Npl3, an RNA-binding protein previously implicated in multiple RNA biogenesis processes. Using Chromatin- and RNA immunoprecipitation, we demonstrate that Npl3 interacts with TERRA and telomeres. Furthermore, we show that Npl3 associates to telomeres in an R-loop dependent manner, as changes in R-loop levels, e.g. at short telomeres, modulate the recruitment of Npl3 to chromosome ends. Through a series of genetic and biochemical approaches we demonstrate that Npl3 binds to TERRA and stabilizes R-loops at short telomeres, which in turn promotes HDR and prevents premature replicative senescence onset. This may have implications for diseases associated with excessive telomere shortening.
2020-01-31 | PXD016772 | Pride
Project description:Haplo-insufficiency of telomerase genes in humans leads to telomere syndromes such as dyskeratosis congenital and idiopathic pulmonary fibrosis. Generation of pluripotent stem cells from telomerase haplo-insufficient donor cells would provide unique opportunities towards the realization of patient-specific stem cell therapies. Recently, pluripotent human embryonic stem cells (ntESCs) have been efficiently achieved by somatic cell nuclear transfer (SCNT). We tested the hypothesis that SCNT could effectively elongate shortening telomeres of telomerase haplo-insufficient cells in the ntESCs using relevant mouse models. Indeed, telomeres of telomerase haplo-insufficient (Terc+/-) mouse cells are elongated in ntESCs. Moreover, ntESCs derived from Terc+/- cells exhibit naïve pluripotency as evidenced by generation of Terc+/-ntESC clone pups by tetraploid embryo complementation (TEC), the most stringent test of naïve pluripotency. These data suggest that SCNT could offer a powerful tool to reprogram telomeres and to discover the factors for robust restoration of telomeres and pluripotency of telomerase haplo-insufficient somatic cells.
2014-11-30 | GSE62692 | GEO
Project description:Genomic instability associated with DNA replication stress is linked to cancer and genetic pathologies in humans. If not properly regulated, replication stress, such as fork stalling and collapse, can be induced at natural replication impediments present throughout the genome. The fork protection complex (FPC) is thought to play a critical role in stabilizing stalled replication forks at several known replication barriers including eukaryotic rDNA genes and the fission yeast mating-type locus. However, little is known about the role of the FPC at other natural impediments including telomeres. Telomeres are considered to be difficult to replicate due to the presence of repetitive GT-rich sequences and telomere-binding proteins. However, the regulatory mechanism that ensures telomere replication is not fully understood. Here, we report the role of the fission yeast Swi1/Timeless, a subunit of the FPC, in telomere replication. Loss of Swi1 causes telomere shortening in a telomerase-independent manner. Our epistasis analyses suggest that heterochromatin and telomere-binding proteins are not major impediments for telomere replication in the absence of Swi1. Instead, repetitive DNA sequences impair telomere integrity in swi1Î mutant cells, leading to the loss of repeat DNA. In the absence of Swi1, telomere shortening is accompanied with an increased recruitment of Rad52 recombinase and more frequent amplification of telomere/subtelomeres, reminiscent of tumor cells that utilize the alternative lengthening of telomeres pathway (ALT) to maintain telomeres. These results suggest that Swi1 ensures telomere replication by suppressing recombination and repeat instability at telomeres. Our studies may also be relevant in understanding the potential role of the FPC in regulation of telomere stability in cancer cells. Genome-wide distributions of Rad52 in wild type and in swi1 deletion in fission yeast The'SP1173_WT ChIP-seq' is an input sample (non-tagged data).
2016-02-25 | E-GEOD-74487 | biostudies-arrayexpress
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:Genomic instability associated with DNA replication stress is linked to cancer and genetic pathologies in humans. If not properly regulated, replication stress, such as fork stalling and collapse, can be induced at natural replication impediments present throughout the genome. The fork protection complex (FPC) is thought to play a critical role in stabilizing stalled replication forks at several known replication barriers including eukaryotic rDNA genes and the fission yeast mating-type locus. However, little is known about the role of the FPC at other natural impediments including telomeres. Telomeres are considered to be difficult to replicate due to the presence of repetitive GT-rich sequences and telomere-binding proteins. However, the regulatory mechanism that ensures telomere replication is not fully understood. Here, we report the role of the fission yeast Swi1/Timeless, a subunit of the FPC, in telomere replication. Loss of Swi1 causes telomere shortening in a telomerase-independent manner. Our epistasis analyses suggest that heterochromatin and telomere-binding proteins are not major impediments for telomere replication in the absence of Swi1. Instead, repetitive DNA sequences impair telomere integrity in swi1Δ mutant cells, leading to the loss of repeat DNA. In the absence of Swi1, telomere shortening is accompanied with an increased recruitment of Rad52 recombinase and more frequent amplification of telomere/subtelomeres, reminiscent of tumor cells that utilize the alternative lengthening of telomeres pathway (ALT) to maintain telomeres. These results suggest that Swi1 ensures telomere replication by suppressing recombination and repeat instability at telomeres. Our studies may also be relevant in understanding the potential role of the FPC in regulation of telomere stability in cancer cells.
2016-02-25 | GSE74487 | GEO