Homo sapiens
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA131905 | ENA |
REPOSITORIES: ENA
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Project description:Mutant template human telomerase RNAs (MT-hTers) have been shown to induce apoptosis in various cancer cells with high telomerase activity. However, the mechanism by which MT-hTers inhibit growth of cancer cells and their effects on normal cells remain unknown. To determine the effects of MT-hTers on normal cells, MT-hTer-47A and -AU5 were introduced into IMR90 lung fibroblasts that have low telomerase levels. Growth of IMR90 cells following MT-hTers infection was not significantly impaired; however, similar treatments in telomerase-overexpressing IMR90 (IMR90 WThTERT) cells inhibited cell proliferation and induced apoptosis. Confocal microscopy showed that MT-hTers induced DNA damage foci i.e. 53BP1 and γ-H2AX in IMR90 WThTERT cells. Microarray analysis revealed that GADD45γ was significantly elevated in MT-hTers treated IMR90 WThTERT cells. MT-hTers also induced ATM phosphorylation at Ser 1981 in IMR90 WThTERT cells, and Western blot analysis revealed high levels of phosphorylated p53 following down-regulation of cellular TRF2 expression in MT-hTers treated IMR90 WThTERT cells. Taken together, we have elucidated that MT-hTers induce double-stranded DNA breaks (DSBs)-like damages in telomerase-positive IMR90 WThTERT cells following phosphorylation of ATM and p53 via suppression of TRF2 which eventually may have led to apoptosis via elevation of GADD45γ.
2011-05-29 | GSE24975 | GEO
Project description:Mutant template human telomerase RNAs (MT-hTers) have been shown to induce apoptosis in various cancerous cells that have high telomerase activity. However, the exact mechanisms by which MT-hTers inhibit the growth of cancer cells and affect normal somatic cells remain largely unknown. To determine the effects of MT-hTers on normal cells, MT-hTer-47A and -AU5 were introduced into IMR90 primary lung fibroblasts that have very low endogenous hTERT levels. Growth of IMR90 cells following MT-hTers infection was not impaired, however, cell proliferation of IMR90 wild-type hTERT (WT-hTERT) cells under MT-hTers-47A and -AU5 treatment was inhibited and increased cell death was observed. FACS analysis also showed that these cells underwent apoptosis. Confocal microscopy revealed that MT-hTers induced DNA damage foci, i.e., 53BP1 and ?-H2AX, in immortalized IMR90 WT-hTERT cells. Microarray analysis of the IMR90 WT-hTERT MT-hTer-47A and -AU5 versus IMR90 MT-hTer-47A and -AU5 revealed that GADD45-? was significantly elevated, and this result was further confirmed following RT-PCR and real time PCR assays. Moreover, we have showed that MT-hTers induce ATM phosphorylation at Ser 1981 in IMR90 WThTERT cells, and Western analysis revealed high levels of phospho p53 expression in these cells following activation of ATM. Our results also suggest that p53-dependent apoptosis in MT-hTers-infected IMR90 WT-hTERT cells could be due to a decreased expression of TRF2. Taken together, we propose a model that MT-hTers induce DSBs-like damages and trigger programmed cell death in IMR90 WT-hTERT cells following ATM-mediated phosphorylation of p53, which in turn upregulate GADD45-?, ultimately leading to apoptosis. MT-hTer-47A and -AU5 were introduced into IMR90 primary lung fibroblasts and immortalized IMR90 WT-hTERT cells. Through microarray analysis, gene expression of MT-hTer-infected IMR90 WT-hTERT cells were compared against MT-hTer-infected IMR90 control cells.
2011-05-28 | E-GEOD-24975 | biostudies-arrayexpress
Project description:Atm+/+ and Atm-/- mouse embryonic fibroblasts were treated with or without DNA damaging agent neocarzinostatin (NCS), and cells were harvested after 4 hours and 8 hours for the microarray analyses of whole-genome long noncoding RNAs. To examine how long noncoding RNAs are regulated in the DNA damage response, we assessed the genome-wide long noncoding RNA expression in Atm+/+ and Atm-/- littermate mouse embryonic fibroblasts (MEFs) treated with or without DNA damage
2013-01-17 | E-GEOD-43425 | biostudies-arrayexpress
Project description:Telomere binding factor 2 (TRF2), is a protein that plays a major role in the maintenance of telomere integrity. In mitotic normal and transformed cells, TRF2 inhibition triggers a rapid telomere DNA damage response that results in cell senescence or apoptosis. Here we provide evidence that TRF2 plays a role suppressing neuronal differentiation. TRF2 interacts with the RE1-silencing transcription factor (REST) in nuclear PML protein-containing compartments of neuronal cells in vivo. Inhibition of TRF2 function with a dominant-negative form of TRF2 elicits a telomeric DNA damage response, and disrupts the TRF2-REST complex resulting in proteasomal degradation of REST. Overexpression of REST impairs the ability of DN-TRF2 to induce neuronal differentiation, indicating that enhanced degradation of REST is sufficient to account for the differentiation-inducing effect of DN-TRF2. REST degradation derepresses RE1-regulated genes (L1CAM, BDNF, b3-tubulin, syntaxin and others) resulting in morphological and functional differentiation of neurons. Our findings identify a novel interaction between the telomeric protein TRF2 and REST which regulates the molecular differentiation program of neurons. Keywords: transfection and molecular inhibition
2007-07-01 | GSE6983 | GEO
Project description:Telomere end-protection by the shelterin complex prevents DNA damage signalling and promiscuous repair at chromosome ends. Evidence suggests that the 3’ single-stranded telomere end can assemble into a lasso-like t-loop configuration, which has been proposed to safeguard chromosome ends from being recognized as DNA double strand breaks. Mechanisms must also exist to transiently disassemble t-loops to allow faithful telomere replication and to permit telomerase access to the 3’-end to solve the end replication problem. However, the regulation and physiological importance of t-loops in end-protection remains uncertain. Here, we identify a CDK phosphorylation site in the shelterin subunit, TRF2 (Ser365), whose dephosphorylation in S-phase by the PP6C/R3 phosphatase provides a narrow window during which the helicase RTEL1 is able to transiently access and unwind t-loops to facilitate telomere replication. Re-phosphorylation of TRF2 on Ser365 outside of S-phase is required to release RTEL1 from telomeres, which not only protects t-loops from promiscuous unwinding and inappropriate ATM activation, but also counteracts replication conflicts at DNA secondary structures arising within telomeres and across the genome. Hence, a phospho-switch in TRF2 coordinates assembly and disassembly of t-loops during the cell cycle, which protects telomeres from replication stress and an unscheduled DNA damage response.
2019-11-25 | PXD014843 | Pride
Project description:As stem cells divide, they acquire mutations that can be passed on to daughter cells. To mitigate potentially deleterious outcomes, cells activate the DNA damage response (DDR) network, which governs several potential cellular outcomes following DNA damage, including repairing DNA or undergoing apoptosis. At the helm of the DDR are three PI3-like kinases including Ataxia Telangiectasia Mutated (ATM). We report here that knockdown of ATM in planarian flatworms enables stem cells to withstand lethal doses of radiation which would otherwise induce cell death. In this context, stem cells circumvent apoptosis, replicate their DNA, and recover function using homologous recombination-mediated DNA repair. Despite radiation exposure, atm knockdown animals survive long-term and regenerate new tissues. These effects occur independently of ATM’s canonical downstream effector p53. Together, our results demonstrate that in planarians, ATM regulates radiation-induced apoptosis. This acute, ATM-dependent apoptosis is a key determinant of long-term animal survival. Our results suggest that inhibition of ATM in these organisms could therefore potentially favor cell survival after radiation without obvious effects on stem cell behavior.
2022-12-25 | GSE190454 | GEO
Project description:Gene expression profiling was performed by use of serial analysis of gene expression (SAGE) on BJ normal human skin fibroblasts, A-T cells, and BJ and A-T cells transduced with hTERT cDNA and expressing telomerase activity. Keywords = telomere Keywords = telomerase Keywords = TERT Keywords = ataxia telangiectasia mutated Keywords = ATM Keywords = serial analysis of gene expression Keywords = SAGE Keywords = fibroblast Keywords: parallel sample
2004-01-16 | E-GEOD-953 | biostudies-arrayexpress
Project description:Atm++ and Atm-- mouse embryonic fibroblasts were treated with DNA damaging agent neocarzinostatin (NCS), and cells were harvested at indicated time points for the microarray analyses of whole-genome miRNAs. To examine how miRNAs are regulated in the DNA damage response, we assessed the genome-wide mature miRNA expression in Atm++ and Atm-- littermate mouse embryonic fibroblasts (MEFs).
2010-12-20 | E-TABM-1092 | biostudies-arrayexpress
Project description:Atm+/+ and Atm-/- mouse embryonic fibroblasts were treated with DNA damaging agent neocarzinostatin (NCS), and cells were harvested at indicated time points for the microarray analyses of whole-genome miRNAs. To examine how miRNAs are regulated in the DNA damage response, we assessed the genome-wide mature miRNA expression in Atm+/+ and Atm-/- littermate mouse embryonic fibroblasts (MEFs).
2010-12-09 | E-GEOD-25916 | biostudies-arrayexpress
Project description:The relationships between profiles of global gene expression and DNA damage checkpoint functions were studied in cells from patients with ataxia telangiectasia (AT). Three telomerase-expressing AT fibroblast lines displayed the expected hypersensitivity to ionizing radiation (IR) and defects in DNA damage checkpoints. Profiles of global gene expression in AT cells were determined at 2, 6 and 24 h after treatment with 1.5 Gy IR or sham-treatment, and were compared to those previously recognized in normal human fibroblasts. Under basal conditions 160 genes or ESTs were differentially expressed in AT and normal fibroblasts, and these were associated by gene ontology with insulin-like growth factor binding and regulation of cell growth. Upon DNA damage, 1091 gene mRNAs were changed in at least two of the three AT cell lines. When compared with the 1811 genes changed in normal human fibroblasts after the same treatment, 715 were found in both AT and normal fibroblasts, including most genes categorized by gene ontology into cell cycle, cell growth and DNA damage response pathways. However, the IR-induced changes in these 715 genes in AT cells usually were delayed or attenuated in comparison to normal cells. The reduced change in DNA-damage-response genes and the attenuated repression of cell-cycle-regulated genes may account for the defects in cell cycle checkpoint function in AT cells. The observation of attenuated and not ablated checkpoint responses in AT cells supports a hypothesis that the ATM- and rad3-related checkpoint kinase ATR also responds to IR-induced DNA damage and complements ATM signaling. Keywords: ATM, cell cycle checkpoint, ionizing radiation, microarray
2007-07-01 | GSE6971 | GEO