Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Non-Classical Functions of Human Topoisomerase I: Genome-wide and Pharmacological Analyses

ABSTRACT: The biological functions of nuclear topoisomerase I (Top1) have been difficult to study because knocking out TOP1 is lethal in metazoans. To reveal the functions of human Top1, we have generated stable Top1siRNA cell lines from colon and breast carcinomas (HCT116-siTop1 and MCF-7-siTop1, respectively). In those cells, Top2 compensates for Top1 deficiency. A prominent feature of the siTop1 cells is genomic instability, with chromosomal aberrations and histone gamma-H2AX foci associated with replication. siTop1 cells also show rDNA and nucleolar alterations, and increased nuclear volume. Genome-wide transcription profiling revealed 55 genes with consistent changes in siTop1 cells. Among them, asparagine synthetase (ASNS) was reduced in siTop1 cells, as it also was in cells with transient Top1 downregulation. Conversely, Top1 complementation increased ASNS, indicating a causal link between Top1 and ASNS expression. Correspondingly, pharmacological profiling showed l-asparaginase hypersensitivity in the siTop1 cells. Resistance to camptothecin, aphidicolin, hydroxyurea and staurosporine, and hypersensitivity to etoposide and actinomycin D demonstrated that Top1, in addition to being the target of camptothecins, also regulates DNA replication, rDNA stability and apoptosis. Overall, our studies demonstrate the pleiotropic nature of human Top1 activities. In addition to its classical DNA nicking-closing functions, Top1 plays critical non-classical roles in genomic stability, gene-specific transcription, and response to various anticancer agents. Keywords: genetic modification design

ORGANISM(S): Homo sapiens

PROVIDER: GSE7161 | GEO | 2008/02/01

SECONDARY ACCESSION(S): PRJNA98165

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Similar Datasets

siRNA profiling of stable HCT116-siTop1 and MCF-7-siTop1 cell lines reveal non-classical functions of human Topoisomerase I:

Project description:The biological functions of nuclear topoisomerase I (Top1) have been difficult to study because knocking out TOP1 is lethal in metazoans. To reveal the functions of human Top1, we have generated stable Top1siRNA cell lines from colon and breast carcinomas (HCT116-siTop1 and MCF-7-siTop1, respectively). In those cells, Top2 compensates for Top1 deficiency. A prominent feature of the siTop1 cells is genomic instability, with chromosomal aberrations and histone gamma-H2AX foci associated with replication. siTop1 cells also show rDNA and nucleolar alterations, and increased nuclear volume. Genome-wide transcription profiling revealed 55 genes with consistent changes in siTop1 cells. Among them, asparagine synthetase (ASNS) was reduced in siTop1 cells, as it also was in cells with transient Top1 downregulation. Conversely, Top1 complementation increased ASNS, indicating a causal link between Top1 and ASNS expression. Correspondingly, pharmacological profiling showed l-asparaginase hypersensitivity in the siTop1 cells. Resistance to camptothecin, aphidicolin, hydroxyurea and staurosporine, and hypersensitivity to etoposide and actinomycin D demonstrated that Top1, in addition to being the target of camptothecins, also regulates DNA replication, rDNA stability and apoptosis. Overall, our studies demonstrate the pleiotropic nature of human Top1 activities. In addition to its classical DNA nicking-closing functions, Top1 plays critical non-classical roles in genomic stability, gene-specific transcription, and response to various anticancer agents. Experiment Overall Design: We are using Affymetrix whole genome array U133 Plus 2, which is a single color microarray platform. For colon experiments, we analyzed 2 different samples as 4 replicates. For breast experiments, we analyzed 2 samples as replicates.

2008-06-15 | E-GEOD-7161 | biostudies-arrayexpress

Ligand-Dependent Enhancer Activation Regulated by Topoisomerase-I Activity

Project description:The discovery that enhancers are regulated transcription units, encoding eRNAs, has raised new questions about the mechanisms of their activation. Here, we report an unexpected molecular mechanism that underlies ligand-dependent enhancer activation, based on DNA nicking to relieve torsional stress from eRNA synthesis. Using dihydrotestosterone (DHT)-induced binding of androgen receptor (AR) to prostate cancer cell enhancers as a model, we show rapid recruitment, within minutes, of DNA topoisomerase I (TOP1) to a large cohort of AR-regulated enhancers. Furthermore, we show that the DNA nicking activity of TOP1 is a prerequisite for robust eRNA synthesis and enhancer activation and is kinetically accompanied by the recruitment of ATR and the MRN complex, followed by additional components of DNA damage repair machinery to the AR-regulated enhancers. Together, our studies reveal a linkage between eRNA synthesis and ligand-dependent TOP1-mediated nicking - a strategy exerting quantitative effects on eRNA expression in regulating AR-bound enhancer-dependent transcriptional programs. Genome-wide binding analysis of AR, TOP1, MRE11 in prostate cancer cell line LNCaP with or without 5alpha-dihydrotestosterone (DHT) treatment. Nascent RNA analysis by global nuclear run-on (GRO-seq) in LNCaP cells transfected with siRNA with or without DHT treatment. Distribution of transcriptionally engaged RNA Pol II in LNCaP cells with or without DHT treatment by precision nuclear run-on and sequencing (PRO-seq).

2015-01-22 | E-GEOD-63202 | biostudies-arrayexpress

Ligand-Dependent Enhancer Activation Regulated by Topoisomerase-I Activity

2015-01-22 | GSE63202 | GEO

G-quadruplex on Chromosomal DNA Negatively Regulates Topoisomerase 1 Activity [ChIP-seq]

Project description:Human DNA topoisomerase 1 (Top1) is a crucial enzyme responsible for alleviating torsional stress on DNA during transcription and replication, thereby maintaining genome stability. Previous researches had found that non-working Top1 interacted extensively with chromosomal DNA in human cells. However, the reason for its retention on chromosomal DNA remained unclear. In this study, we discovered a close association between Top1 and chromosomal DNA, specifically linked to the presence of G-quadruplex (G4) structures. G4 structures, formed during transcription, trap Top1 and hinder its ability to relax neighboring DNAs. Disruption of the Top1-G4 interaction using G4 ligand relieved the inhibitory effect of G4 on Top1 activity, resulting in a further reduction of R-loop levels in cells. Additionally, the activation of Top1 through the use of a G4 ligand enhanced the toxicity of Top1 inhibitors towards cancer cells. Our study uncovers a negative regulation mechanism of human Top1 and highlights a novel pathway for activating Top1.

2024-01-01 | GSE239692 | GEO

G-quadruplex on Chromosomal DNA Negatively Regulates Topoisomerase 1 Activity [CUT&Tag]

2024-01-01 | GSE239690 | GEO

Defining the Rio1 transcriptome in the yeast Saccharomyces cerevisiae

Project description:The conserved Saccharomyces cerevisiae kinase/ATPase Rio1 downregulates rDNA transcription to promote rDNA stability and segregation. To uncover additional roles in transcriptional regulation beyond the rDNA locus we defined the global Rio1 transcriptiome. By NGS we identify 818 differentially expressed genes that are under the transcriptional control of Rio1.

2018-06-14 | GSE70286 | GEO

The Rio1 kinase downregulates RNA polymerase I to promote rDNA stability and segregation

Project description:To sustain growth, budding yeast actively transcribes its ribosomal gene array (rDNA) in the nucoleolus to produce ribosomes and proteins. However, intense transcription during rDNA replication may provoke collisions between RNA polymerase I (Pol I) and the replisome, may cause replication fork instability, double-strand breaks, local recombinations and rDNA instability. The latter is manifested by rDNA array expansion or reduction and the formation of extrachromosomal rDNA circles, anomalies that accelerate aging in yeast. Transcription also interferes with the resolution, condensation and segregation of the sister chromatid rDNA arrays. As a consequence, rDNA segregation lags behind the rest of the yeast genome and occurs in late anaphase when rDNA transcription is temporarily shut off. How yeast promotes the stability and transmission of its rDNA array while satisfying a constant need for ribosomes remains unclear. Here we show that the downregulation of Pol I by the conserved cell cycle kinase Rio1 spatiotemporally coordinates rDNA transcription, replication and segregation. More specifically, Rio1 activity promotes copy-number stability of the replicating rDNA array by curtailing Pol I activity and by localising the histone deacetylase Sir2, which establishes a heterochromatic state that silences rDNA transcription. At anaphase entry, Rio1 and the Cdc14 phosphatase target Pol I subunit Rpa43 to dissociate Pol I from the 35S rDNA promoter. The rDNA locus then condensates and segregates, thereby concluding the genome transmission process. Rio1 is involved in ribosome maturation in the cytoplasm of budding yeast and human cells. Additional engagements in the cytoplasm or roles in the nucleus are unknown. Our study describes its first nuclear engagement as a Pol I silencing kinase. This activity may prove highly relevant as dysregulated RNA polymerase I activity has been associated with cancer initiation and proliferation.

2017-02-10 | GSE54930 | GEO

Depletion of limiting rDNA structural complexes triggers chromosomal instability and replicative aging of Saccharomyces cerevisiae

Project description:Sir2 is a highly conserved NAD+-dependent histone deacetylase that functions in heterochromatin formation and promotes replicative lifespan (RLS) in the budding yeast, Saccharomyces cerevisiae. Within the yeast rDNA locus, Sir2 is required for efficient cohesin recruitment and maintaining stability of the tandem array. In addition to the previously reported depletion of Sir2 in replicatively aged cells, we discovered that subunits of the Sir2 containing complexes, SIR and RENT, were depleted. Several other rDNA structural protein complexes also exhibited age-related depletion, most notably the cohesin complex. We hypothesized that mitotic chromosome instability (CIN) due to cohesin depletion could be a driver of replicative aging. ChIP assays of the residual cohesin (Mcd1-13xMyc) in moderately aged cells showed strong depletion from the rDNA and initial redistribution to the point centromeres, which was then lost in older cells. Despite the shift in cohesin distribution, sister chromatid cohesion was partially attenuated in aged cells and the frequency of chromosome loss was increased. This age-induced CIN was exacerbated in strains lacking Sir2 and its paralog, Hst1, but suppressed in strains that stabilize the rDNA array due to deletion of FOB1 or through caloric restriction (CR). Furthermore, ectopic expression of MCD1 from a doxycycline-inducible promoter was sufficient to suppress rDNA instability in aged cells and to extend RLS. Taken together we conclude that age-induced depletion of cohesin and multiple other nucleolar chromatin factors destabilize the rDNA locus, which then results in general CIN and aneuploidy that shortens RLS.

2019-03-12 | GSE117037 | GEO

Investigation of genetic compensation in tdp1-/- zebrafish embryos

Project description:Tdp1, tyrosyl-DNA phosphodiesterase 1, is an enzyme responsible for the repair of DNA breaks resulting from aberrant topoisomerase 1 activity, called Top1 cleavage complexes (Top1-CCs). Mutation of Tdp1 leads to a progressive neurodegenerative disorder spinocerebellar ataxia with axonal neuropathy 1 (SCAN1). We have generated tdp1-/- zebrafish as a model for SCAN1. The adult fish have a behavioral defect and hypersensitivity to camptothecin (CPT), a Top1 poison. Strikingly, the embryos do not show increased sensitivity to CPT, unlike any other reported vertebrate models, suggesting genetic compensation is at play at this stage. We thus carried out microarray analysis in CPT-treated zebrafish embryos to compare the gene expression profiles of tdp1WT and tdp1-/- genotypes. Gene expression analysis revealed 1,8111 genes that were differentially expressed: 1,071 were upregulated and 740 were downregulated. Sprtn and neil1, two potential compensation candidates were upregulated in the tdp1-/- embryos.

2022-04-19 | GSE148923 | GEO

NEDDylated-Cullin 3 mediates the adaptive response to topoisomerase 1 inhibitors (RNA-Seq)

Project description:DNA topoisomerase 1 (Top1) inhibitors are mainstays of anticancer therapy. These drugs trap Top1 on DNA, stabilizing the Top1-cleavage complex (Top1-cc). The accumulation of Top1-ccs perturbs DNA replication fork progression, leading to DNA breaks and cell death. By analyzing the genomic occupancy and activity of Top1, we show that cells adapt to treatment with multiple doses of Top1 inhibitor by promoting the degradation of Top1-ccs, allowing cells to better tolerate subsequent doses of Top1 inhibitor. The E3-RING Cullin 3 Ligase in complex with the BTBD1 and BTBD2 adaptor proteins promote Top1-cc ubiquitination and subsequent proteasomal degradation. NEDDylation of Cullin 3 activates this pathway and inhibition of protein NEDDylation or depletion of Cullin 3 sensitizes cancer cells to Top1 inhibitors. Collectively, our data identify a novel NEDD8-Cullin 3 pathway involved in the adaptive response to Top1 inhibitors, which can be targeted to improve the efficacy of Top1 drugs in cancer therapy.

2022-11-04 | GSE212469 | GEO

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data