CNOT7 Promotes Radiation Resistance in Colorectal Cancer via XRCC6-Mediated NHEJ DNA Repair Pathway
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PROVIDER: PRJNA1210974 | ENA |
REPOSITORIES: ENA
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Project description:In this study, we identified CNOT7 as a key protein influencing the radiotherapy sensitivity of rectal cancer through proteomic sequencing of patient tissues. Patients with high CNOT7 expression often exhibit poorer prognoses during radiotherapy. We explored the potential mechanisms by which CNOT7 affects radiotherapy sensitivity in CRC. CNOT7 reduces polyubiquitination of K48 linked lysine 526 on XRCC6 by regulating TRIM21. This enhances DNA damage repair primarily mediated by the NHEJ pathway, thereby conferring radiotherapy resistance to colorectal cancer cells. Our study suggests that targeting CNOT7 could serve as a potential therapeutic strategy for rectal cancer patients
2025-04-28 | GSE287014 | GEO
Project description:DNA double strand breaks (DSBs) are a major source of mutations. Both non-homologous-end-joining (NHEJ) and microhomology-mediated-end-joining (MMEJ) DSB repair pathways are error prone and produce deletions, which can lead to cancer. DSBs also lead to epigenetic changes, including demethylation, which is involved in carcinogenesis. Of specific interest is the MMEJ repair pathway, as it requires methylation restoration around the break, as a result of the resection and formation of single stranded (ssDNA) intermediates. While, methylation patterns after homologous recombination (HR) have been partially studied, the methylation status after MMEJ and NHEJ remains poorly reported, and can be relevant for cancer. To study methylation patterns around DSB after NHEJ and MMEJ repair, we used targeted bisulfite-sequencing (BS-seq) to quantify methylation of dozens of single cell clones after induction of DSB by CRISPR. Each single cell clone was classified according to the sequence signature to a specific repair mechanism: NHEJ or MMEJ. Comparison of single cell clones after DSB to control cells, without DSB, demonstrated correct restoration of the methylation levels. No difference in methylation patterns was noticed when comparing NHEJ to MMEJ. Methylation levels in gene body, highly methylated CpGs (n=61, 4000 base pairs around DSB) and in low methylation CpGs (n=19), remained stable after both MMEJ and NHEJ. Gene body methylation persisted even on the background of DNMT3A R882C mutation, the most prevalent preleukemic mutation, in which the de novo methylation machinery is compromised. An exception observed in a single CpG site (ASXL1 995) which demonstrated elevated methylation rate after DSB repair only in the presence of WT DNMT3A. In summary, DNA methylation restoration demonstrated high fidelity after DSB both in methylated and unmethylated gene body, even in cases where DNA resections and deletions occurred.
2022-09-11 | E-MTAB-12037 | biostudies-arrayexpress
Project description:DNA double strand breaks (DSBs) are a major source of mutations. Both non-homologous-end-joining (NHEJ) and microhomology-mediated-end-joining (MMEJ) DSB repair pathways are error prone and produce deletions, which can lead to cancer. DSBs also lead to epigenetic changes, including demethylation, which is involved in carcinogenesis. Of specific interest is the MMEJ repair pathway, as it requires methylation restoration around the break, as a result of the resection and formation of single stranded (ssDNA) intermediates. While, methylation patterns after homologous recombination (HR) have been partially studied, the methylation status after MMEJ and NHEJ remains poorly reported, and can be relevant for cancer. To study methylation patterns around DSB after NHEJ and MMEJ repair, we used targeted bisulfite-sequencing (BS-seq) to quantify methylation of dozens of single cell clones after induction of DSB by CRISPR. Each single cell clone was classified according to the sequence signature to a specific repair mechanism: NHEJ or MMEJ. Comparison of single cell clones after DSB to control cells, without DSB, demonstrated correct restoration of the methylation levels. No difference in methylation patterns was noticed when comparing NHEJ to MMEJ. Methylation levels in gene body, highly methylated CpGs (n=61, 4000 base pairs around DSB) and in low methylation CpGs (n=19), remained stable after both MMEJ and NHEJ. Gene body methylation persisted even on the background of DNMT3A R882C mutation, the most prevalent preleukemic mutation, in which the de novo methylation machinery is compromised. An exception observed in a single CpG site (ASXL1 995) which demonstrated elevated methylation rate after DSB repair only in the presence of WT DNMT3A. In summary, DNA methylation restoration demonstrated high fidelity after DSB both in methylated and unmethylated gene body, even in cases where DNA resections and deletions occurred.
2022-08-25 | E-MTAB-12061 | biostudies-arrayexpress
Project description:Radiotherapy is one of the mainstays for the treatment of hepatocellular carcinoma (HCC); however, a substantial fraction of HCC patients develops radioresistance and eventually suffer from tumour progression or relapse, a major impediment to the use of radiotherapy. One of the main goals in HCC management is to elucidate the mechanisms underlying radioresistance and identify novel therapeutic targets to improve the patients' prognosis. In this study, we report a DNA repair enhancer, human positive cofactor 4 (PC4), that promotes NHEJ-based DNA repair and renders HCC cells resistant to radiation. Mechanistically, PC4 interacts with PARP1 and directs Ku complex PARylation, resulting in successful recruitment of the Ku complex to damaged chromatin and increasing the efficiency of NHEJ repair. Clinically, PC4 is highly expressed in tumour tissues, which is correlated with poor prognosis in HCC patients. Taken together, our data suggest that PC4 is a DNA repair driver that can be targeted to radiosensitize HCC.
2023-10-24 | PXD042218 | Pride
Project description:Tardigrades can survive remarkable doses of ionizing radiation, up to about 1000 times the lethal dose for humans. How they do so is incompletely understood. We found that the tardigrade Hypsibius exemplaris suffers DNA damage upon gamma irradiation, but damage is repaired. We show that tardigrades have a specific and robust response to ionizing radiation: irradiation induces a rapid, dramatic upregulation of many DNA repair genes. By expressing tardigrade genes in bacteria, we validate that increased expression of some repair genes can suffice to increase radiation tolerance. We show that at least one such gene is necessary for tardigrade radiation tolerance. Tardigrades’ ability to sense ionizing radiation and massively upregulate specific DNA repair pathway genes may represent an evolved solution for maintaining DNA integrity.
2024-12-13 | PXD047724 | Pride
Project description:Tardigrades can survive remarkable doses of ionizing radiation, up to about 1000 times the lethal dose for humans. How they do so is incompletely understood. We found that the tardigrade Hypsibius exemplaris suffers DNA damage upon gamma irradiation, but damage is repaired. We show that tardigrades have a specific and robust response to ionizing radiation: irradiation induces a rapid and dramatic upregulation of many DNA repair genes. By expressing tardigrade genes in bacteria, we validate that increased expression of some repair genes can suffice to increase radiation tolerance. We show that at least one such gene is necessary for tardigrade radiation tolerance. Tardigrades’ ability to sense ionizing radiation and massively upregulate specific DNA repair pathway genes may represent an evolved solution for maintaining DNA integrity.
2024-04-12 | GSE253470 | GEO
Project description:Tardigrades can survive remarkable doses of ionizing radiation, up to about 1000 times the lethal dose for humans. How they do so is incompletely understood. We found that the tardigrade Hypsibius exemplaris suffers DNA damage upon gamma irradiation, but damage is repaired. We show that this tardigrade has a specific and robust response to ionizing radiation: irradiation induces a rapid upregulation of many DNA repair genes. This upregulation is unexpectedly extreme, making some DNA repair transcripts among the most abundant transcripts in the animal. By expressing tardigrade genes in bacteria, we validate that increased expression of some repair genes can suffice to increase radiation tolerance. We show that at least one such gene is important for tardigrade radiation tolerance. We hypothesize that tardigrades’ ability to sense ionizing radiation and massively upregulate specific DNA repair pathway genes may represent an evolved solution for maintaining DNA integrity.
2024-04-12 | GSE240501 | GEO
Project description:Purpose: The recombinant endonucleases introduce double-strand breaks (DSBs) in genomic DNA at targeted sites and non-homologous end-joining (NHEJ) pathways repair the breaks introducing indels into the genome. To investigate whether there is another NHEJ pathway or if A-NHEJ and C-NHEJ are redundant, we examined NHEJ edits in HeLa cells. Methods: To test among these possibilities, we engineered a NHEJ reporter system using targeted TALEN induced double strand DNA breaks. C-NHEJ was blocked in XRCC4(-/-) cells and A-NHEJ was blocked pharmacologically with mirin. To assess how NHEJ was maintained, differentially expressed genes were determined by RNA-Seq. Results: When both C-NHEJ and A-NHEJ are blocked, edits were still observed. No changes in expression of DNA repair genes was observed. However, when both NHEJ pathways were blocked, genes from several pathways including DNA damage response, hypoxic response, chromatin packaging, p53 response and two genes that stimulate homologous recombination were differentially expressed. Conclusions: NHEJ is maintained when both NHEJ pathways are blocked through a transcriptional response that must compensate for the inhibited steps in both pathways.
2020-12-31 | GSE135274 | GEO
Project description:In mammalian cells, classical non-homologous end joining (c-NHEJ) is critical for DNA double-strand break repair induced by ionizing radiation and during V(D)J recombination in developing B and T lymphocytes. Recently, PAXX was identified as a new c-NHEJ core component. We report here, that PAXX-deficient cells exhibit a cellular phenotype uncharacteristic of a deficiency in c-NHEJ core components. PAXX-deficient cells display normal sensitivity to radiomimetic drugs, are proficient in transient V(D)J recombination assays, and do not shift towards higher micro-homology usage in plasmid repair assays. Although PAXX-deficient cells lack c-NHEJ phenotypes, PAXX forms a ternary complex with Ku bound to DNA. Formation of this complex involves an interaction with Ku70 and requires a bare DNA extension for stability. Moreover, the relatively weak Ku-dependent stimulation of LIG4/XRCC4 activity by PAXX is unmasked by XLF ablation. Thus, PAXX plays an accessory role during c-NHEJ that is largely overlapping with XLF’s function.
2016-10-06 | PXD004659 | Pride
Project description:In double-strand DNA damage repair, non-homologous end joining (NHEJ) is more error prone than homologous recombination repair (HRR), indicating that the relative prevalence of NHEJ may lead to more incorrect repair and thus to increases in chromosome damage. If DNA damage is extensive and cells are unable to repair that damage they typically undergo apoptosis. The mechanism(s) by which cells decide to switch from DNA repair to apoptosis is unknown. Since DNA repair and apoptosis are both energy-demanding processes, the answer may involve ATP utilization. We used human mitochondrial mutant cell lines obtained from people with phenotypic manifestations of compromised ATP generation. We hypothesized that these cells may not have adequate capacity for dealing with the additional demands for ATP required for repairing DNA damage after genotoxic exposure, perhaps making the cells more prone to undergo apoptosis instead of initiating repair. This study describes changes in the expression of genes involved in NHEJ or HRR, as well as genes involved in apoptosis, in one normal and two mitochondrial mutant human cell lines following ionizing radiation exposure. Compared to normal cells, both mutant cell lines showed reduced expression of genes involved in NHEJ and HRR. Analysis of expression changes in genes involved in apoptosis revealed marked increases in expression in the mutants compared to normal cells. These results indicate that following ionizing radiation exposure, mitochondrial mutant cells have decreased levels of mRNA expression of DNA repair genes and increased expression levels of genes involved in apoptosis compared to normal cells. This study provides information that might be useful in characterizing energy dependent processes following exposure to stress or genotoxic agents.
2010-04-24 | GSE21428 | GEO