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Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Short telomeres compromise M-NM-2-cell signaling and survival

ABSTRACT: The factors that underlie the increasing incidence of diabetes with age are poorly understood. We examined whether telomere length, known to decrease with age, plays a role in the age-dependent increased incidence of diabetes. We show that in mice with short telomeres, insulin secretion is impaired and leads to glucose intolerance despite the presence of an intact M-NM-2-cell mass. Islets from mice with short telomeres displayed evidence of M-NM-2-cell dysfunction, and in response to glucose, had defective mitochondrial membrane depolarization as well as Ca2+ handling which limited insulin release. Short telomeres induced the hallmarks of senescence including premature accumulation of p16INK4a, and altered gene expression of key pathways essential for signaling and insulin secretion. Short telomeres also had an additive damaging effect to endoplasmic reticulum stress which occurs in the late stages of type 2 diabetes. This manifested as more severe hyperglycemia in insulin mutant Akita mice which had a more profound loss of M-NM-2-cell mass and increased M-NM-2-cell apoptosis. Our data identify impaired signaling in the setting of senescence as a novel mechanism of telomere-mediated disease, and implicate telomere length as a determinant of risk and pathogenesis in diabetes. The experiment is designed to analyze gene expression profiles of islets from mice with short telomeres compared to those of wildtype mice.

ORGANISM(S): Mus musculus

SUBMITTER: Nini Guo

PROVIDER: E-GEOD-25040 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Short telomeres compromise β-cell signaling and survival

Project description:The factors that underlie the increasing incidence of diabetes with age are poorly understood. We examined whether telomere length, known to decrease with age, plays a role in the age-dependent increased incidence of diabetes. We show that in mice with short telomeres, insulin secretion is impaired and leads to glucose intolerance despite the presence of an intact β-cell mass. Islets from mice with short telomeres displayed evidence of β-cell dysfunction, and in response to glucose, had defective mitochondrial membrane depolarization as well as Ca2+ handling which limited insulin release. Short telomeres induced the hallmarks of senescence including premature accumulation of p16INK4a, and altered gene expression of key pathways essential for signaling and insulin secretion. Short telomeres also had an additive damaging effect to endoplasmic reticulum stress which occurs in the late stages of type 2 diabetes. This manifested as more severe hyperglycemia in insulin mutant Akita mice which had a more profound loss of β-cell mass and increased β-cell apoptosis. Our data identify impaired signaling in the setting of senescence as a novel mechanism of telomere-mediated disease, and implicate telomere length as a determinant of risk and pathogenesis in diabetes.

2013-10-01 | GSE25040 | GEO

Telomere length effect on genes near the telomere in myoblasts

Project description:We examined differential expression of genes within 10MBs of telomeres in myoblasts with long or short telomeres We offer telomere looping with telomere length as a partial mechanistic explanation for the changes gene expression that is observed. Compare expression of genes within 10MB of the telomere in normal myoblasts with long (15 kb) and short (6 kb) telomeres.

2014-07-17 | E-GEOD-48973 | biostudies-arrayexpress

Gene expression data from type II pneumocytes from adult mice with and without Trf2

Project description:Gas exchange in the mammalian lung occurs in the alveolar sacs lined by epithelial cells that form a barrier allowing effective oxygen diffusion. Telomere syndromes have their most common manifestation in degenerative disease of the alveoli, both pulmonary fibrosis and emphysema. We tested the role of telomere dysfunction by inducing deletion of the telomere binding protein Trf2 in type 2 alveolar epithelial cells (AEC2s) that both express the gene encoding surfactant protein C and constitute the regenerative compartment of the alveolar epithelium. Acquired telomere dysfunction in these cells preferentially induced cellular senescence, and mouse lungs were marked by an inflammatory response even though the telomere dysfunction was restricted to the epithelium. Senescent AECs had altered gene expression that differentially fell in inflammatory cell signaling pathways. Bleomycin challenge was uniformly fatal, and Trf2-depleted cells failed to generate clonal alveolar colonies in vitro. The telomere dysfunction response in AEC2s was in part p53-dependent, and we found evidence of a p53-mediated paracrine survival signal to the mesenchyme. These data indicate that telomere dysfunction in the alveolar epithelium limits its regenerative capacity and is sufficient to induce inflammation. It may thus be a primary driving event in telomere-mediated lung disease. Efforts to restore epithelial regenerative capacity may be an effective approach in a subset of fibrosis and emphysema patients. We studied the gene expression changes in adult type II pneumocytes 7 days after deleting Trf2. Mice carried floxed allele of Trf2 and mTmG reporter allele. Type II pneumocytes were collected by FACs sorting GFP+ cells from lungs 7 days after administering tamoxifen. 6 total samples were analysed. Three were from control samples that were heterozygous for Trf2 and three samples had Trf2 deleted.

2015-04-20 | E-GEOD-56892 | biostudies-arrayexpress

Expression data by telomere elongation

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

Telomere length effect on genes near the telomere in myoblasts

2014-07-17 | GSE48973 | GEO

Telomere Shortening Impairs PGC Fate Decision [RNA-seq]

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2022-08-31 | GSE157303 | GEO

Telomere Shortening Impairs PGC Fate Decision [ATAC-seq]

2022-08-31 | GSE157301 | GEO

Npl3 stabilizes R-loops at telomeres to prevent accelerated replicative senescence

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

Expression data by telomere elongation in vivo (xenograft)

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

Chromatin modifiers and recombination factors promote a telomere fold-back structure, that is lost during replicative senescence

Project description:Telomeres have the ability to adopt a lariat conformation and hence, engage in long and short distance intra-chromosome interactions. Budding yeast telomeres were proposed to fold back into subtelomeric regions, but a robust assay to quantitatively characterize this structure has been lacking. Therefore, it is not well understood how the interactions between telomeres and non-telomeric regions are established and regulated. We employ a telomere chromosome conformation capture (Telo-3C)approach to directly analyze telomere folding and its maintenance in S. cerevisiae. We identify the histone modifiers Sir2, Sin3 and Set2 as critical regulators for telomere folding, which suggests that a distinct telomeric chromatin environment is a major requirement for the folding of yeast telomeres. We demonstrate that telomeres are not folded when cells enter replicative senescence, which occurs independently of short telomere length. Indeed, Sir2, Sin3 and Set2 protein levels are decreased during senescence and their absence may thereby prevent telomere folding. Additionally, we show that the homologous recombination machinery, including the Rad51 and Rad52 proteins, as well as the checkpoint component Rad53 are essential for establishing the telomere fold-back structure. This study outlines a method to interrogate telomere-subtelomere interactions at a single unmodified yeast telomere. Using this method, we provide insights into how the spatial arrangement of the chromosome end structure is established and demonstrate that telomere folding is compromised throughout replicative senescence.

2020-11-20 | PXD021085 | Pride

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