Massively Multiplexed Sequencing-Based Host Cell Reactivation Assay Profiles DNA Repair at Single-Nucleotide and -Cell Resolution [scRNA]
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE330132 | GEO | 2026/08/20
REPOSITORIES: GEO
Similar Datasets
Project description:Defects in DNA repair are clinical biomarkers for therapeutic vulnerabilities in multiple cancer types. However, the characterization of DNA repair in cancer remains bottlenecked by a lack of reliable genomic predictors and the low throughput of existing functional assays. Here, we present mmHCR-seq, a sequencing-based and massively multiplexed Host Cell Reactivation assay that enables parallel quantification of functional repair efficiency and accuracy across all major repair pathways via RNA-seq readout. We demonstrate that mmHCR-seq can detect deficiencies and measure kinetics of nine DNA repair pathways simultaneously. The single-nucleotide resolution revealed lesion-dependent kinetics for base excision repair intermediates. By integrating mmHCR-seq with single-cell RNA-seq, we mapped repair capacity in a 19-cell line pool at cellular resolution and coupled repair phenotypes to expression states. Therein, cell cycle effects were unraveled without the need for synchronization. Overall, mmHCR-seq provides a scalable, high-resolution platform for dissecting DNA repair mechanisms and identifying new repair-associated vulnerabilities in cancer.
2026-08-20 | GSE330134 | GEO
Project description:The fidelity of DNA replication is governed by a network of DNA repair mechanisms. Defects in replication fork protection can fuel genome instability in cancer, while also creating cancer-specific vulnerabilities. Here, we provide a comprehensive proteomic characterization of the replication fork response to topoisomerase 1 inhibition, a widely used mainstay chemotherapy. We reveal profound changes in the fork proteome and chromatin environment in response to seDSBs and topological stress, and classify fork repair factors according to their specificity for broken and stalled forks. These distinct fork responses also oppositely affect nucleosome occupancy and nuclear membrane interactions. ATM inhibition dramatically rewired the fork breakage response, revealing that ATM promotes HR-dependent fork restart by concomitantly promoting DNA-end resection and suppressing DSB associated protein ubiquitination and NHEJ. Together, this collection of damaged fork proteomes provides an ample resource to understand fork repair mechanisms and identify druggable targets and novel cancer vulnerabilities.
2021-01-15 | PXD018092 | Pride
Project description:Active DNA demethylation in mammals involves TET-mediated iterative oxidation of 5-methylcytosine (5mC)/5-hydroxymethylcytosine (5hmC) and subsequent excision repair of highly oxidized cytosine bases 5-formylcytosine (5fC)/5-carboxylcytosine (5caC) by Thymine DNA glycosylase (TDG). However, quantitative and high-resolution analysis of active DNA demethylation activity remains challenging. Here we describe M.SssI methylase-assisted bisulfite sequencing (MAB-seq), a method that directly maps 5fC/5caC at single-base resolution. Genome-wide MAB-seq allows systematic identification of 5fC/5caC in Tdg-depleted embryonic stem cells, thereby generating a base-resolution map of active DNA demethylome. A comparison of 5fC/5caC and 5hmC distribution maps indicates that catalytic processivity of TET enzymes correlates with local chromatin accessibility. MAB-seq also reveals strong strand asymmetry of active demethylation within palindromic CpGs. Integrating MAB-seq with other base-resolution mapping methods enables quantitative measurement of cytosine modification states at key transitioning steps of active demethylation pathway, and reveals a regulatory role of 5fC/5caC excision repair in active DNA demethylation cascade. Analysis of 5fC/5caC excision repair-dependent active DNA demethylome by MAB-seq in mouse embryonic stem cells.
2014-11-02 | E-GEOD-62631 | biostudies-arrayexpress
Project description:Comprehensive Model Description
Overview
This model simulates the cellular response to DNA damage under conditions of ATM/ATR deficiency—such as in ataxia telangiectasia—and predicts the potential benefits of drug repositioning with Omaveloxolone and spermidine. It integrates several interconnected modules: DNA damage production and repair, ATM/ATR–p53 signaling, NRF2/KEAP1 regulation, spermidine-induced autophagy (with additional positive modulation of ATR signaling), and downstream p53 effectors involved in cell fate decisions.
1. DNA Damage Production and Repair Module
Basal DNA Damage Production:
DNA damage is continuously generated at a constant rate, representing both endogenous processes and low-level environmental stress. This reaction acts as a source term for the DNA_damage species.
Repair Pathways:
Several mechanisms work to reduce DNA damage:
ATM-Mediated Repair: Active ATM facilitates the direct repair of DNA damage.
ATR-Mediated Repair: Active ATR, in cooperation with CHK1, repairs DNA damage.
NRF2-Mediated Repair: Active NRF2 triggers antioxidant responses that reduce DNA damage.
Autophagy-Mediated Repair: The autophagy pathway, induced by spermidine, repairs DNA damage in a saturable manner (modeled using Michaelis–Menten kinetics). This ensures that even a significant pulse of damage is only partially repaired, leaving a nonzero steady-state level.
2. ATM/ATR–p53 Signaling Module
ATM and ATR Activation:
DNA damage, along with a positive input from TOPBP1, converts inactive ATM and ATR to their active forms. Under ATM/ATR-deficient conditions (as in ataxia telangiectasia), the activation is severely reduced, resulting in higher levels of unrepaired DNA damage.
p53 Activation:
Both ATM_active and ATR_active phosphorylate and activate p53. Active p53 then acts as a central integrator of the DNA damage signal.
Regulatory Proteins:
HDAC4:
HDAC4 cycles between inactive and active states. Its active form can attenuate p53 activity.
TOPBP1:
TOPBP1 is activated in a DNA damage–dependent manner and helps promote ATR activation.
CK2:
CK2 is a constitutively active kinase that supports TOPBP1 activation.
3. NRF2/KEAP1 Module and Omaveloxolone
NRF2 Activation:
DNA damage stimulates the conversion of NRF2_inactive to NRF2_active. Active NRF2 enhances antioxidant defenses and promotes DNA repair.
KEAP1-Mediated Degradation:
Under normal conditions, KEAP1 targets NRF2_inactive for degradation, keeping NRF2 activity low.
Modulation by Omaveloxolone:
Omaveloxolone is modeled as a constant (boundary) species. It inhibits KEAP1’s activity, thereby reducing NRF2 degradation. This shifts the balance in favor of increased NRF2_active, which boosts the cell’s antioxidant and repair responses.
4. Spermidine-Induced Autophagy and Positive Modulation of ATR Signaling
Spermidine is modeled as a constant species and has two major effects:
Induction of Autophagy:
Spermidine promotes the conversion of Autophagy_inactive to Autophagy_active. The active autophagy machinery repairs DNA damage using a saturable (Michaelis–Menten) mechanism. This pathway helps clear DNA damage but is limited by its maximum capacity.
Enhancement of ATR Signaling:
Spermidine also positively modulates ATR signaling by enhancing the CK2-mediated activation of TOPBP1. In the model, the effective rate of TOPBP1 activation is increased proportionally to the concentration of spermidine. This is represented by a modulation factor, where the effective rate constant for TOPBP1 activation is multiplied by a term that increases with spermidine concentration. The boosted TOPBP1_active level in turn enhances ATR activation, partially compensating for the loss of ATM/ATR function.
5. Downstream p53 Targets: Cell Fate Decisions
Activated p53 regulates cell fate by inducing the production of several downstream effectors:
p21:
p21 is produced in response to p53 activation and is associated with cell cycle arrest and senescence. Its production is balanced by a degradation reaction.
BAX and PUMA:
Both BAX and PUMA are pro-apoptotic proteins. They are produced in proportion to p53_active and are subsequently degraded. Their relative levels help determine whether the cell will undergo apoptosis.
6. Reaction Kinetics (Qualitative Overview)
Mass-Action and Michaelis–Menten Kinetics:
Most reactions in the model are governed by mass-action kinetics. For example, activation and deactivation reactions (such as ATM activation by DNA damage or p53 activation by ATM/ATR) follow simple proportional relationships.
Saturable Repair Processes:
The autophagy-mediated DNA repair reaction uses Michaelis–Menten kinetics to reflect a saturation effect; when DNA damage is high, the repair rate approaches a maximum value, ensuring that not all damage is cleared immediately.
Modulatory Effects:
Spermidine increases the effective rate of TOPBP1 activation (and hence ATR activation) via a modulation term that is proportional to its concentration. Omaveloxolone reduces the degradation rate of NRF2 by inhibiting KEAP1.
Biological Implications and Model Utility
ATM/ATR Deficiency:
In ataxia telangiectasia, ATM/ATR functions are diminished, leading to increased DNA damage. The model simulates this scenario and examines how alternative pathways (NRF2-mediated repair, autophagy, and enhanced ATR signaling via spermidine) help mitigate the damage.
Drug Repositioning Predictions:
The model can be used to predict the outcomes of repositioning drugs:
Omaveloxolone is expected to stabilize NRF2, enhancing antioxidant defenses and reducing DNA damage.
Spermidine acts dually by promoting autophagy (with a saturable repair capacity) and by boosting ATR signaling via TOPBP1 activation.
Cell Fate Outcomes:
The downstream p53 targets (p21, BAX, and PUMA) serve as markers for cell cycle arrest/senescence and apoptosis. By simulating the dynamics of these proteins, the model can predict whether a cell is likely to survive, arrest its cycle, or undergo apoptosis based on the integrated response to DNA damage and drug interventions.
Conclusion
This detailed and comprehensive model integrates multiple layers of the cellular response to DNA damage in ATM/ATR-deficient conditions. It includes upstream damage sensing, multiple repair pathways (including direct kinase-mediated repair, antioxidant responses via NRF2, and autophagy-mediated repair), and downstream effectors that determine cell fate. Omaveloxolone and spermidine are modeled to specifically modulate the NRF2/KEAP1 pathway and ATR signaling (via TOPBP1 activation), respectively. This framework provides a robust platform for exploring drug repositioning strategies and predicting cellular outcomes in diseases such as ataxia telangiectasia.
2025-11-25 | MODEL2503190002 | BioModels
Project description:DNA Double Strand Breaks (DSBs) are harmful lesions that require rapid detection and repair in order to avoid toxic genomic rearrangements. DSBs elicit the so called DNA Damage Response (DDR), largely relying on ataxia telangiectasia mutated (ATM) and DNA Protein Kinase (DNAPK), two members of the PI3K-like kinase family, whose respective functions during the sequential steps of the DDR remains controversial. Using the DIvA cell line, expressing the AsiSI restriction enzyme, we have investigated the role of ATM and DNAPK in several aspects of the DDR upon induction of multiple clean DSBs throughout the human genome. High resolution mapping revealed that they are activated and spread in cis on a confined region surrounding all DSBs, independently of the pathway used for repair. However, a thorough analysis of repair kinetics, H2AX domain establishment and H2AX foci structure and dynamics revealed non overlapping functions for the two kinases once recruited at DSBs. Our results suggest that ATM is not solely acting on chromatin marks but also on chromatin organisation in order to ensure repair accuracy and survival.
2015-09-30 | E-MTAB-2992 | biostudies-arrayexpress
Project description:Through various approaches we demonstrate that SYCP1 is aberrantly re-expressed in tumor cells, where it actively promotes DNA damage repair, cell cycle progression, and malignant growth. SYCP1 binds chromatin at regulatory elements and directly controls transcriptional programs governing genome maintenance, including key effectors such as CCNB1, PCNA, RAD51C, and H2AX. Loss of SYCP1 impairs DNA repair kinetics, attenuates tumor cell proliferation and migration, and increases sensitivity to chemotherapeutics cisplatin and gemcitabine. Mechanistically, SYCP1 interfaces with chromatin remodeling complexes and transcription factors SP1 and SP2, modulating their genomic occupancy and facilitating oncogenic transcriptional outputs. Our findings illuminate a previously unrecognized moonlighting function of SYCP1 in somatic cancer cells and position it as a critical chromatin-associated regulator of genome stability. In the presented RNA-seq experiment, we aimed to identify the differentially expressed genes between samples of wild type MCF7 cells and the samples with CRISPR/Cas9-mediated SYCP1 gene KO.
2026-03-15 | E-MTAB-15849 | biostudies-arrayexpress
Project description:We have adapted the eXcision Repair-sequencing (XR-seq) method to generate single-nucleotide resolution dynamic repair maps of UV-induced cyclobutane pyrimidine dimers (CPDs) and (6-4) pyrimidine-pyrimidone photoproducts [(6-4)PPs] in the Saccharomyces cerevisiae genome. We find that these photoproducts are removed from the genome primarily by incisions 13-18 nucleotides 5’ and 6-7 nucleotides 3’ to the UV damage that generate 21-27 nt-long excision products. Analyses of the excision repair kinetics both in single genes and at the genome-wide level reveal strong transcription-coupled repair of the transcribed strand (TS) at early time points followed by predominantly non-transcribed strand (NTS) repair at later stages. We have also characterized the excision repair level as a function of transcription level. The availability of high-resolution and dynamic repair maps should aid in future repair and mutagenesis studies in this model organism.
2018-04-12 | GSE110621 | GEO
Project description:Intra-tumor heterogeneity of tumor-initiating cell (TIC) activity drives colorectal cancer (CRC) progression and therapy resistance. Here, we used single-cell mRNA-sequencing (scRNA-seq) of patient-derived CRC models to decipher distinct cell subpopulations based on their transcriptional profiles. Cell type-specific expression modules of stem-like, transit amplifying-like, and differentiated CRC cells resemble differentiation states of normal intestinal epithelial cells. Strikingly, identified subpopulations differ in proliferative activity and metabolic state. In summary, we here show at single-cell resolution that transcriptional heterogeneity identifies functional states during TIC differentiation. Targeting transcriptional states associated to cancer cell differentiation might unravel vulnerabilities in human CRC.
2021-05-07 | PXD018230 | Pride
Project description:To establish if PCNA ubiquitylation affects the DNA replication kinetics of specific loci, we compared rates of DNA replication across the genome between rad18+ and rad18-delta cells using the BrdU-IP sequencing method. We mapped BrdU-incorporation at 300-bp resolution and subsequent informatics analysis was performed to generate datasets of replication kinetics.
2017-05-12 | E-GEOD-70033 | biostudies-arrayexpress
Project description:The RNA-guided DNA endonuclease Cas9 is a powerful tool for genome editing. Little is known about the kinetics and fidelity of the double-strand break (DSB) repair process that follows a Cas9 cutting event in living cells. Here, we developed a strategy to measure the kinetics of DSB repair for single loci in human cells. Quantitative modeling of repaired DNA in time series after Cas9 activation reveals variable and often slow repair rates, with half-life times up to ~10 h. Furthermore, repair of the DSBs tends to be error-prone. Both classical and microhomology-mediated end-joining pathways contribute to the erroneous repair. Estimation of their individual rate constants indicates that the balance between these two pathways changes over time and can be altered by additional ionizing radiation. Our approach provides quantitative insights into DSB repair kinetics and fidelity in single loci, and indicates that Cas9-induced DSBs are repaired in an unusual manner.
2018-05-01 | GSE113129 | GEO