ABL Kinase Inactivation Promotes Transcription-Replication Conflicts and Compromises Replication Forks Revealing a Therapeutic Vulnerability in Metastatic Small Cell Lung Cancer
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PROVIDER: PRJNA1222963 | ENA |
REPOSITORIES: ENA
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Project description:Small cell lung cancer (SCLC) is a highly aggressive neuroendocrine cancer that is typically metastatic upon diagnosis, and has low overall survival. Despite being highly sensitive to first-line chemotherapy or radiotherapy, most patients with SCLC experience relapse and succumb from systemic metastasis. Here we report that inactivation of ABL tyrosine kinases markedly impaired outgrowth of metastatic SCLC tumors in mouse models, resulting in prolonged animal survival. Mechanistically, ABL inactivation in SCLC resulted in increased accumulation of transcription-replication conflicts, compromised replication fork progression, impaired expression and function of proteins implicated in transcription-coupled homologous recombination, and increased DNA damage. Because ABL inactivation increased DNA damage, we evaluated whether blocking the activity DNA damage-repair pathways in the presence of ABL inhibitors might synergize to promote SCLC cell death. We found that co-inactivation of ABL kinase and Ataxia telangiectasia and Rad3-related (ATR), the primary responder of replication stress, synergistically inhibited SCLC cell growth in vitro, and impaired metastatic dissemination and outgrowth compared to single agent treated mice. Thus, combined inactivation of ABL kinase and DNA damage-repair pathways might be exploited to block dissemination and outgrowth of SCLC metastases
2025-02-13 | GSE289452 | GEO
Project description:During the S-phase, conflicts of replication forks with RNA Polymerase II (RNAPII) threaten genomic stability. While the PAF complex can resolve such conflicts during elongation, the particularly deleterious conflicts with stalling RNAPII are resolved by an as of yet unknown mechanism. Here we show that the MYCN oncoprotein forms a ternary complex with RNAPII and the nuclear RNA exosome, a 3’‑5’ exoribonuclease complex. Together with TFIIS, this complex restarts promoter‑proximal RNAPII, allows escape from co-directional transcription-replication conflicts and prevents double‑strand break accumulation. In cells lacking RNA exosome function, MYCN globally terminates transcription. MYCN-mediated termination is triggered by ATM‑dependent recruitment of BRCA1, which then stabilizes nuclear mRNA decapping complexes. Disruption of mRNA decapping activates ATR, indicative of head-on transcription-replication conflicts, and inhibits DNA replication. We propose that MYCN resolves transcription-replication conflicts via this two-step mechanism to sustain the rapid proliferation of neuroendocrine tumor cells.
2021-12-10 | GSE164568 | GEO
Project description:During the S-phase, conflicts of replication forks with RNA Polymerase II (RNAPII) threaten genomic stability. While the PAF complex can resolve such conflicts during elongation, the particularly deleterious conflicts with stalling RNAPII are resolved by an as of yet unknown mechanism. Here we show that the MYCN oncoprotein forms a ternary complex with RNAPII and the nuclear RNA exosome, a 3’‑5’ exoribonuclease complex. Together with TFIIS, this complex restarts promoter‑proximal RNAPII, allows escape from co-directional transcription-replication conflicts and prevents double‑strand break accumulation. In cells lacking RNA exosome function, MYCN globally terminates transcription. MYCN-mediated termination is triggered by ATM‑dependent recruitment of BRCA1, which then stabilizes nuclear mRNA decapping complexes. Disruption of mRNA decapping activates ATR, indicative of head-on transcription-replication conflicts, and inhibits DNA replication. We propose that MYCN resolves transcription-replication conflicts via this two-step mechanism to sustain the rapid proliferation of neuroendocrine tumor cells.
2021-12-10 | GSE164567 | GEO
Project description:During the S-phase, conflicts of replication forks with RNA Polymerase II (RNAPII) threaten genomic stability. While the PAF complex can resolve such conflicts during elongation, the particularly deleterious conflicts with stalling RNAPII are resolved by an as of yet unknown mechanism. Here we show that the MYCN oncoprotein forms a ternary complex with RNAPII and the nuclear RNA exosome, a 3’‑5’ exoribonuclease complex. Together with TFIIS, this complex restarts promoter‑proximal RNAPII, allows escape from co-directional transcription-replication conflicts and prevents double‑strand break accumulation. In cells lacking RNA exosome function, MYCN globally terminates transcription. MYCN-mediated termination is triggered by ATM‑dependent recruitment of BRCA1, which then stabilizes nuclear mRNA decapping complexes. Disruption of mRNA decapping activates ATR, indicative of head-on transcription-replication conflicts, and inhibits DNA replication. We propose that MYCN resolves transcription-replication conflicts via this two-step mechanism to sustain the rapid proliferation of neuroendocrine tumor cells.
2021-12-10 | GSE164555 | GEO
Project description:Chromosome duplication normally initiates via the assembly of replication fork complexes at defined origins. DNA synthesis by any one fork is thought to cease when it meets another travelling in the opposite direction, at which stage the replication machinery may simply dissociate before the nascent strands are finally ligated. But what actually happens is not clear. Here we present evidence consistent with the idea that every fork collision has the potential to trigger re-replication of the already replicated DNA, thus posing a threat to genomic integrity. In Escherichia coli this threat is kept at bay by the RecG DNA translocase. Without RecG, replication initiates where forks meet, establishing new forks with the potential to sustain cell growth and division in the absence of an active origin. The studies reported raise the question of how eukaryotic and archaeal cells are able to exploit multiple origins for the duplication of each chromosome without any apparent ill effect from the consequent multiple fork collisions. Measurement of replication dynamics (marker frequency analysis; MFA) for E. coli strains, including wild-type and various mutants.
2013-07-22 | E-GEOD-41975 | biostudies-arrayexpress
Project description:R-loops are three-stranded nucleic acid structures composed of an RNA:DNA hybrid and displaced DNA strand. These structures can halt DNA replication when formed co- transcriptionally in the opposite orientation to replication fork progression. Recent studies have shown that replication forks stalled by co-transcription R-loops can be restarted by a mechanism involving fork cleavage by MUS81 endonuclease, followed by reactivation of transcription, and fork religation by the DNA ligase IV (LIG4)/XRCC4 complex. However, how R-loops are eliminated to allow the sequential restart of transcription and replication in this pathway remains elusive. Here, we identified the human DDX17 helicase as a factor that associates with R-loops and counteracts R-loop-mediated replication stress to preserve genome stability. We show that DDX17 unwinds RNA:DNA hybrids in vitro and promotes MUS81-dependent restart of R-loop-stalled forks in human cells in a manner dependent on its helicase activity. Loss of DDX17 helicase induces accumulation of R-loops and the formation of R-loop-dependent anaphase bridges and micronuclei. These findings establish DDX17 as a component of the MUS81-LIG4 pathway for resolution of R-loop-mediated transcription- replication conflicts, which may be involved in R-loop unwinding.
2022-11-02 | PXD034331 | Pride
Project description:Replication fork reversal is a key protective mechanism against replication stress in higher eukaryotic cells and occurs via a series of coordinated enzymatic reactions. The Bloom syndrome gene product, BLM, is a member of the highly conserved RecQ helicase family and has been implicated in this process, but its precise regulation and role remain poorly understood. Here, we show that, upon replication stress, the GCFC domain-containing protein TFIP11 competes with the BLM helicase for association with stalled replication forks, thereby facilitates RAD51-mediated stalled fork reversal. Consequently, loss of TFIP11 results in aberrant accumulation of BLM at stalled forks, which in turn compromises RAD51 recruitment, impairs replication stress-induced fork reversal and slowing, hypersensitizes cells to replication stress-inducing agents, and enhances chromosomal instability. These findings reveal a previously unidentified regulatory mechanism that modulates the activities of BLM and RAD51 at stalled forks and thus genome integrity.
2024-05-24 | PXD042222 | Pride
Project description:Faithful duplication of DNA is essential for the maintenance of genomic stability in all organisms. DNA synthesis proceeds bi-directionally with continuous synthesis of leading strand DNA and discontinuous synthesis of lagging strand DNA. Herein, we describe a method of enriching and Sequencing of Protein-Associated Nascent strand DNA (eSPAN) to detect whether a protein binds the leading- and lagging-strands of DNA replication forks. We show that Pol-epsilon, PCNA, Cdc45, Mcm6 and Mcm10 preferentially associate with leading strands, whereas Pol-alpha, Pol32, Pol-delta, Rfa1 and Rfc1 associate with lagging strands of hydroxyurea (HU)-stalled replication forks. In contrast, PCNA is enriched at lagging strands of normal replication forks in wild type cells and HU-stalled forks in cells lacking Elg1. These studies demonstrate a strategy to reveal proteins at leading and lagging strands of DNA replication forks, and suggest that the unloading of PCNA from lagging strands of HU-stalled replication forks helps maintain genome integrity. We synchronized yeast cells at G1 and released into early S phase in the presence of BrdU, a nucleotide analog that can be incorporated into newly synthesized DNA strand, and hydroxyurea (HU), a ribonucleotide reductase inhibitor. HU has no effect on initiation of DNA replication at early replication origins, but inhibit late replication firing. In addition, replication forks are stalled due to depletion of dNTPs. We then performed chromatin-immunoprecipitation of 12 proteins of interest following a standard procedure. Protein-bound DNAs were then reverse-crosslinked and double strand DNA was denatured. Nascent DNA was enriched by immunoprecipitation using anti-BrdU antibodies. The recovered ssDNA was first marked with ligation to one oligo at 3M-bM-^@M-^Y end before conversion to dsDNA for library preparation and sequencing. In this way, the directionality of ssDNA and therefore strand information of each sequenced DNA were known. The sequencing tag was mapped to both Watson (red) and Crick (blue) strands of the reference genome. In addition to ChIP-eSPAN, we also performed BrdU-IP and single strand DNA sequence (BrdU-ssSeq) and protein ChIP followed by single-strand DNA sequencing (ChIP-ssSeq) for each corresponding ChIP-eSPAN experiment. We also performed Mcm4 and Mcm6 ChIP-seq using cells synchronized at G1 phase of the cell cycle for identification of replication origins in comparison with published dataset. Some protein ChIP-ssSeq and ChIP-eSPAN experiments were repeated and the data fits well each other. Therefore, we did not repeat all protein ChIP-ssSeq and ChIP-eSPAN experiments.
2014-10-29 | E-GEOD-52614 | biostudies-arrayexpress
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.
2023-08-01 | GSE218239 | GEO
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.
2023-08-01 | GSE222839 | GEO