Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

BRCA2 suppresses “head-on” transcription-replication conflicts incurred by dormant origin firing at transcription termination sites [RNA-seq]

ABSTRACT: BRCA2 is a tumor suppressor protein responsible for safeguarding the cellular genome from genotoxicity and replication stress, but the mechanism(s) by which this is achieved remains elusive. Here, we provide evidence that BRCA2 acts as a critical suppressor of “head-on” transcription-replication conflicts (HO-TRCs). Using Okazaki-fragment sequencing (Ok-seq) and computational analysis, we identified new origins (dormant origins) that are activated near the transcription termination sites (TTS) of highly expressed, long genes in response to replication stress. Dormant origins are a source for HO-TRCs, and drug treatments that inhibit dormant origin firing led to a reduction in HO-TRCs, R-loop formation, and DNA damage. Using super-resolution microscopy, we showed that HO-TRC events track with elongating RNA polymerase II, but not with transcription initiation. Importantly, RNaseH2 is recruited to sites of HO-TRCs in a BRCA2-dependent manner to help alleviate toxic R-loops associated with HO-TRCs. Collectively, our results identify a new source of genomic instability caused by HO-TRCs in BRCA2-deficient ovarian cancer precursor cells, providing a new strategy in modulating HO-TRCs to enhance genomic instability

ORGANISM(S): Homo sapiens

PROVIDER: GSE239857 | GEO | 2024/03/28

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Similar Datasets

BRCA2 suppresses “head-on” transcription-replication conflicts incurred by dormant origin firing at transcription termination sites [Ok-seq]

Project description:BRCA2 is a tumor suppressor protein responsible for safeguarding the cellular genome from genotoxicity and replication stress, but the mechanism(s) by which this is achieved remains elusive. Here, we provide evidence that BRCA2 acts as a critical suppressor of “head-on” transcription-replication conflicts (HO-TRCs). Using Okazaki-fragment sequencing (Ok-seq) and computational analysis, we identified new origins (dormant origins) that are activated near the transcription termination sites (TTS) of highly expressed, long genes in response to replication stress. Dormant origins are a source for HO-TRCs, and drug treatments that inhibit dormant origin firing led to a reduction in HO-TRCs, R-loop formation, and DNA damage. Using super-resolution microscopy, we showed that HO-TRC events track with elongating RNA polymerase II, but not with transcription initiation. Importantly, RNaseH2 is recruited to sites of HO-TRCs in a BRCA2-dependent manner to help alleviate toxic R-loops associated with HO-TRCs. Collectively, our results identify a new source of genomic instability caused by HO-TRCs in BRCA2-deficient ovarian cancer precursor cells, providing a new strategy in modulating HO-TRCs to enhance genomic instability

2024-03-28 | GSE239856 | GEO

Primase excites the competition of templating transcription and lagging replication to boost DNA damage

Project description:Head-on transcription-replication conflicts (HO-TRCs) cause R-loops and DNA damage. We realized that HO-TRCs are the natural competition for templating transcription and lagging replication in the same DNA strand (termed TemLag competition), however, the regulatory mechanisms behind are unclear. We previously identified a chloroplast-localized RNase H1 protein AtRNH1C that can remove R-loops and relax HO-TRCs for genome integrity. Through the mutagenesis screen, we identified that the chloroplast-localized primase ATH exacerbates TemLag competition in the atrnh1c mutant. A mutation in ATH weakens the binding affinity of DNA, thus slowing down DNA replication and relieving TemLag competition. Overexpression of ATH boosts TemLag competition and intensifies DNA damage. Interestingly, strand-specific DNA damage sequencing reveals that TemLag competition induces single-strand DNA damage of the competitive strand at the end of transcription. These results illustrated a potentially conserved mechanism among organisms, of which the primase antagonizes R-loop clearance machinery to exaggerate TemLag competition and genome instability.

2023-12-06 | GSE215443 | GEO

Aldehyde exposure unmasks genome instability in cells heterozygous for clinically relevant BRCA2 mutations

Project description:Abnormalities provoked in human cells heterozygous for clinically relevant truncating mutations in BRCA2 by their exposure to naturally occurring aldehydes define a mechanism promoting carcinogenesis in mutation carriers. The ubiquitous metabolite and environmental toxin, formaldehyde, triggers replication fork instability and structural chromosomal aberrations in BRCA2 heterozygous cells. These abnormalities arise from a previously unrecognized effect of formaldehyde to selectively induce the proteasomal degradation of BRCA2, inducing functional haploinsufficiency only in cells where BRCA2 expression is already compromised by a heterozygous mutation. Similar effects are observed with acetaldehyde, a toxic product of alcohol catabolism. Replication fork instability and chromosomal aberrations in aldehyde-exposed cells arise from the unscheduled accumulation of RNA-DNA hybrids, revealing a mechanism driving genomic instability in BRCA2 heterozygous cells. We propose a model for cancer pathogenesis in which aldehyde exposure unmasks the carcinogenic potential of heterozygous BRCA2 mutations, with public health implications in mutation carriers.

2017-06-02 | PXD006106 | Pride

HUWE1 interaction partners in HCT116 cells (TMT)

Project description:Deregulation of RNA Polymerase II (RNAPII) by oncogenic signaling leads to collisions of RNAPII with DNA synthesis machinery (transcription-replication conflicts, TRCs). TRCs can result in DNA damage and underlie genomic instability in tumor cells. Here we provide evidence that elongating RNAPII promotes activation of the ATM kinase at TRCs to drive DNA repair. We show the ATPase Wrnip1 that binds and protects stalled replication forks, associates with RNAPII and limits ATM activation. Wrnip1 binding to elongating RNAPII requires catalytic activity of the ubiquitin ligase Huwe1. Mutation of Huwe1 promotes the transfer of Wrnip1 onto replisome and induces TRCs stimulating ATM activation on RNAPII. This mechanism is evoked early upon replicative stress to induce Wrnip1 translocation and ATM signaling at TRCs. Thus, although primarily considered as genotoxic events, TRCs can provide a mechanism to maintain genome stability under replicative stress.

2023-07-31 | PXD037677 | Pride

HUWE1 interaction partners in HCT116 cells (label free)

2023-07-31 | PXD037812 | Pride

pSer2-RNAPII interaction partners in MEF cells (label free)

2023-07-31 | PXD037680 | Pride

MiDAS in BRCA2-deficient cells originate at early S-phase transcription-replication conflicts

Project description:Multiple replication abnormalities cause cells lacking BRCA2 to enter mitosis with under-replicated DNA and to activate mitotic DNA synthesis (MiDAS). However, the precise position of these MiDAS sites, as well as their origin, remains unknown. Here we labelled mitotic nascent DNA and performed high-throughput sequencing to identify at high-resolution the sites where MiDAS occurs in the absence of BRCA2. This approach revealed 150 genomic loci affected by MiDAS, which map within regions replicating during early S-phase and are therefore distinct from the aphidicolin-induced common fragile sites. Moreover, these sites largely localise near early firing origins and within genes transcribed in early S, suggesting that they stem from transcription-replication conflicts (TCRs). Inhibiting transcription with 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) during early S-phase abrogates MiDAS. Strikingly, MiDAS sites co-localise with genomic loci where R-loops form in unchallenged conditions, suggesting that R-loop accumulation caused by BRCA2 inactivation leads to DNA lesion which are repaired by MiDAS. RAD52 is required in this process, as its abrogation in BRCA2-deficient cells reduces the rate of MiDAS and causes DNA damage accumulation in G1. Furthermore, MiDAS sites triggered by BRCA2 inactivation are hotspots for genomic rearrangement in BRCA2-mutated breast tumours. These results indicate that BRCA2 acts in early S-phase to protect TRC- and R-loop-induced DNA lesions, thereby preventing them from becoming a source of genomic instability and tumorigenesis.

2022-08-01 | GSE196163 | GEO

RNAPII-dependent ATM signaling at collisions with replication forks [DSB]

2023-08-01 | GSE218239 | GEO

RNAPII-dependent ATM signaling at collisions with replication forks [CUT&RUN]

2023-08-01 | GSE218238 | GEO

RNAPII-dependent ATM signaling at collisions with replication forks [ChIP-seq]

2023-08-01 | GSE218237 | GEO