SMUG1 promotes telomere maintenance through telomerase RNA end-processing
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ABSTRACT:
PROVIDER: PRJNA479447 | ENA |
REPOSITORIES: ENA
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Project description:Single-strand selective uracil DNA-glycosylase (SMUG1) associates with the DKC1-H/ACA ribonucleoprotein complex, which is essential for telomerase biogenesis. We show herein, that SMUG1 interacts with the telomerase RNA component, hTERC, and is required for co-transcriptional processing of the nascent transcript towards mature hTERC. We demonstrate that SMUG1 regulates the presence of base modifications between the CR4/CR5 region and the H-box situated towards the 3´-end of hTERC. Increased levels of hTERC base modifications are accompanied by reduced DKC1 binding. Loss of SMUG1 leads to an imbalance between mature hTERC and its processing intermediates, leading to the accumulation of 3´-polyadenylated and 3´-extended intermediates that are degraded in an EXOSC10-independent RNA degradation pathway. Consequently, SMUG1-deprived cells, present telomerase deficiency leading to impaired bone marrow proliferation in SMUG1-knockout mice.
2019-08-11 | GSE116580 | GEO
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 | iProX
Project description:Mutations in genes encoding components of the telomerase holoenzyme complex result in a spectrum of rare genetic disorders known as telomere diseases, including dyskeratosis congenita (DC). A consistent finding in DC due to pathogenic mutations in DKC1, which encodes dyskerin, is decreased steady-state levels of the non-coding RNA component of telomerase (TERC) and thus impaired telomere maintenance. Dyskerin binds hundreds of other small nucleolar RNAs (snoRNAs). However, the mechanisms by which DKC1 mutations cause variable impacts on these snoRNAs are poorly understood, which is a barrier to understanding disease mechanisms in DC beyond impaired telomere maintenance. Here, using somatic and induced pluripotent stem cells (iPSCs) from DC patients with DKC1 mutations and CRISPR-Cas9-engineered iPSCs, we show that mutations in the N-terminal extension domain (NTE) of dyskerin dysregulate the biogenesis of a subset of snoRNAs, with the most prominent effect on scaRNA13 (small Cajal body-specific RNA 13). In patient iPSCs carrying the del37L dyskerin NTE-domain mutation but not in those with C-terminal mutations, nascent scaRNA13 transcripts showed a discrete population of 3´-extended forms, as seen in the setting of DC-causing mutations in the PARN (polyA-specific ribonuclease) gene. By deep sequencing of RNA 3´ ends, we found that aberrant scaRNA13 transcripts were composed of genomically-encoded extensions and post-transcriptionally oligoadenylated species, mediated by the noncanonical polymerase PAPD5, which counters PARN. NTE domain mutations generated using CRISPR-Cas9 engineering of the endogenous DKC1 recapitulated the scaRNA13 3´-end processing defects seen in del37L patient cells. Conversely, repair of the DKC1 del37L mutation and genetic or pharmacological manipulation of PAPD5 rescued scaRNA13 end processing defects and steady-state levels. Analysis of the human telomerase cryo-EM structure showed that the dyskerin NTE interacts with 3´ end of bound RNA, suggesting that mutations in this domain impair 3´ end protection of nascent scaRNA13 in addition to canonical functions in snoRNA stabilization. Our results provide mechanistic insights into the interplay of dyskerin and the PARN/PAPD5 axis in the biogenesis and accumulation of snoRNAs beyond TERC, which has important implications for our broader understanding of ncRNA dysregulation in human diseases.
2022-08-01 | GSE190173 | GEO
Project description:Telomere maintenance mechanisms (TMM) are a hallmark of high-risk neuroblastoma, and are conferred by activation of telomerase or alternative lengthening of telomeres (ALT). However, detection of TMM is not yet part of the clinical routine, and consensus on TMM detection, especially on ALT assessment, remains to be achieved. Based on our results we here propose a workflow to reliably detect TMM in neuroblastoma. We show that unambiguous classification is feasible following a stepwise approach that determines both, activation of telomerase and ALT. The workflow proposed in this study can be used in clinical routine and provides a framework to systematically evaluate telomere maintenance mechanisms in risk stratification and treatment allocation of neuroblastoma patients.
2022-09-19 | GSE211653 | GEO
Project description:Background and Aims: Telomere dysfunction can increase tumor initiation by induction of chromosomal instability, but initiated tumor cells need to reactivate telomerase for genome stabilization and tumor progression. However, this concept has not been proven in vivo since appropriate mouse models were lacking. Here, we analyzed hepatocarcinogenesis (i) in a novel mouse model of inducible telomere dysfunction on a telomerase-proficient background, (ii) in telomerase knockout mice with chronic telomere dysfunction (G3 mTerc-/-), and (iii) in wild-type mice with functional telomeres and telomerase. Transient or chronic telomere dysfunction enhanced the rates of chromosomal aberrations during hepatocarcinogenesis, but only telomerase-proficient mice exhibited significantly increased rates of macroscopic tumor formation and cancer cell proliferation in response to telomere dysfunction. In contrast, telomere dysfunction resulted in pronounced accumulation of DNA damage, cell cycle arrest and apoptosis in telomerase-deficient liver tumors. Together, these data provide the first in vivo evidence that transient telomere dysfunction during early and late stages of tumorigenesis can promote chromosomal instability and carcinogenesis in telomerase-proficient mice in the absence of additional genetic checkpoint defects at germline level. RNA from liver tumors derived from from DEN treated TTD+ mice TTD- mice and RNA from normal liver 48h-72h after doxycycline induced transient telomere dysfunction in TTD+ and TTD- liver were isolated and RNA was extracted. Agilent Mouse 4x44K v2 arrays were used. DNA from liver tumors and corrresponding kidney as control derived from from DEN treated TTD+ mice, TTD- mice and mTERC-/- G3 mice was isolated and extracted using Phenol/Chloroform. Agilent Mouse 4x44K and Mouse 1x244K arrays were used.
2012-03-30 | E-GEOD-36813 | biostudies-arrayexpress
Project description:Background and Aims: Telomere dysfunction can increase tumor initiation by induction of chromosomal instability, but initiated tumor cells need to reactivate telomerase for genome stabilization and tumor progression. However, this concept has not been proven in vivo since appropriate mouse models were lacking. Here, we analyzed hepatocarcinogenesis (i) in a novel mouse model of inducible telomere dysfunction on a telomerase-proficient background, (ii) in telomerase knockout mice with chronic telomere dysfunction (G3 mTerc-/-), and (iii) in wild-type mice with functional telomeres and telomerase. Transient or chronic telomere dysfunction enhanced the rates of chromosomal aberrations during hepatocarcinogenesis, but only telomerase-proficient mice exhibited significantly increased rates of macroscopic tumor formation and cancer cell proliferation in response to telomere dysfunction. In contrast, telomere dysfunction resulted in pronounced accumulation of DNA damage, cell cycle arrest and apoptosis in telomerase-deficient liver tumors. Together, these data provide the first in vivo evidence that transient telomere dysfunction during early and late stages of tumorigenesis can promote chromosomal instability and carcinogenesis in telomerase-proficient mice in the absence of additional genetic checkpoint defects at germline level.
2012-03-31 | GSE36813 | GEO
Project description:Mutations in the poly(A) ribonuclease (PARN) gene cause telomere diseases including familial idiopathic pulmonary fibrosis (IPF) and dyskeratosis congenita (DC)1,2, but how PARN deficiency impacts telomere maintenance is unclear. Here, using somatic cells and induced pluripotent stem (iPS) cells from DC patients with PARN mutations, we show that PARN is required for the 3′ end maturation of the telomerase RNA component (TERC). Patient cells as well as immortalized cells in which PARN is disrupted show decreased levels of TERC. Deep sequencing of TERC RNA 3′ termini reveals that PARN is required for removal of posttranscriptionally acquired oligo(A) tails that target nuclear RNAs for degradation. Diminished TERC levels and the increased oligo(A) forms of TERC are normalized by restoring PARN, which is limiting for TERC maturation in cells. Our results reveal a novel role for PARN in the biogenesis of TERC, and provide a mechanism linking PARN mutations to telomere diseases. mRNA sequencing of fibroblasts, induced pluripotent stem cells, and 293 cell line.
2015-09-08 | E-GEOD-71709 | biostudies-arrayexpress
Project description:Primary telomerase RNA transcripts are processed into shorter mature forms that assemble into a complex with the catalytic subunit and provide the template for telomerase activity. In diverse fungi telomerase RNA 3â end processing involves a single cleavage reaction by the spliceosome akin to the first step of splicing. Longer forms of human telomerase RNA (hTR) have been reported, but how the mature form of precisely 451 nucleotides is generated is still unknown. We now show that the splicing inhibitor isoginkgetin causes accumulation of long hTR transcripts, but find no evidence for a direct role for splicing in hTR processing. Instead, isoginkgetin mimics the effects of inhibiting the RNA exosome. Depletion of exosome components and accessory factors reveals functions for the cap binding complex (CBC) and the nuclear exosome targeting (NEXT) complex in hTR turnover. Whereas longer transcripts are predominantly degraded, shorter precursor RNAs are oligo-adenylated by TRF4-2 and either processed by poly (A) specific ribonuclease (PARN) or degraded by the exosome. Our results reveal that hTR biogenesis involves a kinetic competition between RNA processing and quality control pathways and suggest new treatment options for dyskeratosis congenita caused by mutations in RNA processing factors. We cloned and sequenced 3â ends by RLM-RACE coupled with high-throughput sequencing to gain further insights into hTR processing.
2015-11-25 | E-GEOD-73776 | biostudies-arrayexpress
Project description:Critically short telomeres activate p53-mediated apoptosis, resulting in organ failure and causing malignant transformation. Mutations in genes responsible for telomere maintenance are linked to a number of specific human diseases. We derived induced pluripotent stem cells (iPSCs) from patients with mutations in the TERT and TERC telomerase genes. Telomerase-mutant iPSCs elongated telomeres, but at a lower rate than healthy iPSCs, and the magnitude of the elongation deficit correlated with the specific mutation’s impact on telomerase activity. However, elongation significantly varied among iPSC clones harboring the same mutation, and was affected by genetic and environmental factors. iPSCs cultured in hypoxia showed increased telomere length. Potential influence of residual expression of reprogramming factors on telomerase regulation and telomere length was ruled out by excising the transgenes after successful reprogramming. Evidence for telomerase-independent telomere elongation was not observed in these cells. We demonstrate that telomerase is required for telomere elongation in iPSCs and uncover heterogeneity in telomere maintenance even between clones derived from individual patients or siblings with the same mutation, indicating that telomere phenotype may be influenced by acquired and environmental agents. Our data underscore the necessity of studying multiple clones when using iPSCs to model disease. The exon array were done to validate the pluripotent phenotype of the derived normal and telomerase mutant iPSC and to potentially identify differentially expressed genes in mutant iPSC. Objective: confirming pluripotency by comparing telomerase mutated-, control-iPSC to human ESC and to their parental somatic cells (fibroblast used for iPSC derivation) 20 samples total, 5 different fibroblast cells, 13 iPSC lines, 1 ES line (H1) from different passages
2013-02-11 | E-GEOD-42869 | biostudies-arrayexpress
Project description:Primary telomerase RNA transcripts are processed into shorter mature forms that assemble into a complex with the catalytic subunit and provide the template for telomerase activity. In diverse fungi telomerase RNA 3’ end processing involves a single cleavage reaction by the spliceosome akin to the first step of splicing. Longer forms of human telomerase RNA (hTR) have been reported, but how the mature form of precisely 451 nucleotides is generated is still unknown. We now show that the splicing inhibitor isoginkgetin causes accumulation of long hTR transcripts, but find no evidence for a direct role for splicing in hTR processing. Instead, isoginkgetin mimics the effects of inhibiting the RNA exosome. Depletion of exosome components and accessory factors reveals functions for the cap binding complex (CBC) and the nuclear exosome targeting (NEXT) complex in hTR turnover. Whereas longer transcripts are predominantly degraded, shorter precursor RNAs are oligo-adenylated by TRF4-2 and either processed by poly (A) specific ribonuclease (PARN) or degraded by the exosome. Our results reveal that hTR biogenesis involves a kinetic competition between RNA processing and quality control pathways and suggest new treatment options for dyskeratosis congenita caused by mutations in RNA processing factors.
2015-11-25 | GSE73776 | GEO