A rewiring of DNA replication mediated by MRE11 exonuclease underlies primed-to-naive cell de-differentiation
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PROVIDER: PRJNA1068604 | ENA |
REPOSITORIES: ENA
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Project description:Mouse embryonic stem cells (mESCs) in the primed pluripotency state, that resembles the post-implantation epiblast, can be de-differentiated in culture to anaivestate that resembles the pre-implantation inner cell mass.We report that primed-to-naive mESC transition entails a significant slowdown of DNA replication forks and the compensatory activation of dormant origins. Using iPOND (“isolation of proteins on nascent DNA”) coupled to mass spectrometry, we identify key changes in replisome composition that are responsible for these effects. Naive mESC forks are enriched in MRE11 nuclease and other DNA repair proteins. MRE11 is recruited to newly synthesized DNA in response to transcription-replication conflicts, and its inhibition or genetic downregulation in naive mESCs is sufficient to restore the fork speed observed in primed cells. Notably, MRE11 is required for the efficient primed-to-naive mESC transition, demonstrating a direct link between DNA replication dynamics and the mESC de-differentiation process
2024-04-03 | GSE254126 | GEO
Project description:Pluripotent stem cells can give rise to the three embryonic germ layers and the characterization of their properties is crucial to exploit their therapeutic potential. Mouse embryonic stem cells (mESCs) are isolated and usually maintained in vitro in a primed state that resembles the post-implantation epiblast features. Furthermore, primed mESCs can be de-differentiated to a naive state that resembles the pre-implantation inner cell mass (ICM). Cell differentiation or genotoxic stress, among others, can alter DNA replication, which is a flexible process able to adapt to different cellular contexts. Here, we demonstrate that primed-to-naive mESC reprogramming triggers replication fork slowdown, increased fork asymmetry and a compensatory activation of dormant origins. Using iPOND (“isolation of proteins on nascent DNA”) coupled to mass spectrometry we have characterized the changes in replisome composition between naive and primed mESCs. Several DNA repair factors, including MRE11 nuclease, are enriched in naive mESCs forks, while factors involved in ubiquitin-dependent protein metabolism are enriched in primed mESC forks. We report that primed-to-naive mESC de-differentiation promotes recruitment of MRE11 to the forks in response to transcription-replication conflicts, underlying the DNA replication rewiring required for efficient mESC reprogramming.
2024-04-03 | PXD041946 | Pride
Project description:he human MRE11/RAD50/NBS1 (MRN) complex plays a crucial role in sensing and repairing DNA DSB. MRE11 possesses 3’-5’ exonuclease and endonuclease activity and forms the core of the multifunctional MRN complex. We previously identified a C-terminally truncated form of MRE11 (TR-MRE11) associated with post-translational MRE11 degradation. Here we identified the approximate cleavage site of TR-MRE11 at 559-580 amino acids, its DNA damage repair function and the factors regulating TR-MRE11 accumulation. The nuclease enzymatic activity of TR-MRE11 was dramatically reduced, associated with a lack of DNA binding efficiency, whilst TR-MRE11 still interacted efficiently with RAD50 and NBS1. Lack of the MRE11 C-terminal resulted in deficient HR repair and increased cellular radiosensitivity. Knockdown of SprT-like N-terminal domain (SPRTN), an essential metalloprotease for DNA-protein crosslink repair, resulted in failure of MRE11 cleavage, with TR-MRE11 protein levels being positively correlated with SPRTN protein expression. The presence of this DNA repair-defective C-terminal truncation could explain the finding of high MRE11 expression, by immunohistochemistry using an antibody against MRE11 prior to the C-terminal, being associated with survival following radical radiotherapy in cancer patients. Ultimately, understanding the functional differences between intact and repair-defective MRE11 may lead to improvements in patient outcomes through a more informed choice of treatment.
2021-02-23 | PXD017964 | Pride
Project description:Platinum resistance is a clinical challenge in ovarian cancer. Platinating agents induce DNA damage which activate Mre11 nuclease directed DNA damage signalling and response (DDR). Upregulation of DDR may promote chemotherapy resistance. Here we have comprehensively evaluated Mre11 in epithelial ovarian cancers. In clinical cohort that received platinum- based chemotherapy (n=331), Mre11 protein overexpression was associated with aggressive phenotype and poor progression free survival (PFS) (p=0.002). In the ovarian cancer genome atlas (TCGA) cohort (n=498), Mre11 gene amplification was observed in a subset of serous tumours (5%) which correlated highly with Mre11 mRNA levels (p<0.0001). Altered Mre11 levels was linked with genome wide alterations that can influence platinum sensitivity. At the transcriptomic level (n=1259), Mre11 overexpression was associated with poor PFS (p=0.003). ROC analysis showed an area under the curve (AUC) of 0.642 for response to platinum-based chemotherapy. Pre-clinically, Mre11 depletion by gene knock down or blockade by small molecule inhibitor (Mirin) reversed platinum resistance in ovarian cancer cells and in 3D spheroid models. Importantly, Mre11 inhibition was synthetically lethal in platinum sensitive XRCC1 deficient ovarian cancer cells and 3D-spheroids. Selective cytotoxicity was associated with DNA double strand break (DSB) accumulation, S-phase cell cycle arrest and increased apoptosis. We conclude that pharmaceutical development of Mre11 inhibitors is a viable clinical strategy for platinum sensitization and synthetic lethality in ovarian cancer.
2022-07-04 | GSE160540 | GEO
Project description:Gene amplification, copy-number increases of particular genes and surrounding genomic segments, promotes cancer progression and acquired therapy resistance. Thus, understanding genetic traits that confer gene amplification proficiency is important. The primary step for gene amplification is spontaneous DNA rearrangements initiated by DNA breaks. Here we show that mammalian cells became gene amplification-proficient when we knocked down Mre11/Rad50/Nbs1 (MRN) complex, a multifunctional complex that guards the genome from DNA breaks. Cells with reduced Mre11 experienced severe replication stress, with marked increases of single-stranded breaks followed by double-stranded breaks during DNA replication. Such breaks underlay for the increase in spontaneous gene amplification. Other traits associated with replication stress, such as impaired intra-S phase checkpoint and global transcriptional changes in DNA metabolism genes also contributed to gene amplification proficiency. Our results define Mre11 deficiency as a cause of replication stress and gene amplification proficiency and provide a candidate marker for aggressive cancer phenotypes. We sequenced four samples: 2 control, GFP-expressing samples and 2 Mre11 knockdown cells
2015-03-05 | E-GEOD-59487 | biostudies-arrayexpress
Project description:Platinum resistance is a clinical challenge in ovarian cancer. Platinating agents induce DNA damage which activate Mre11 nuclease directed DNA damage signalling and response (DDR). Upregulation of DDR may promote chemotherapy resistance. Here we have comprehensively evaluated Mre11 in epithelial ovarian cancers. In clinical cohort that received platinum- based chemotherapy (n=331), Mre11 protein overexpression was associated with aggressive phenotype and poor progression free survival (PFS) (p=0.002). In the ovarian cancer genome atlas (TCGA) cohort (n=498), Mre11 gene amplification was observed in a subset of serous tumours (5%) which correlated highly with Mre11 mRNA levels (p<0.0001). Altered Mre11 levels was linked with genome wide alterations that can influence platinum sensitivity. At the transcriptomic level (n=1259), Mre11 overexpression was associated with poor PFS (p=0.003). ROC analysis showed an area under the curve (AUC) of 0.642 for response to platinum-based chemotherapy. Pre-clinically, Mre11 depletion by gene knock down or blockade by small molecule inhibitor (Mirin) reversed platinum resistance in ovarian cancer cells and in 3D spheroid models. Importantly, Mre11 inhibition was synthetically lethal in platinum sensitive XRCC1 deficient ovarian cancer cells and 3D-spheroids. Selective cytotoxicity was associated with DNA double strand break (DSB) accumulation, S-phase cell cycle arrest and increased apoptosis. We conclude that pharmaceutical development of Mre11 inhibitors is a viable clinical strategy for platinum sensitization and synthetic lethality in ovarian cancer.
2022-07-04 | GSE198648 | GEO
Project description:Mre11 inhibition by oncolytic adenovirus associates with autophagy and underlies synergy with ionizing radiation
2009-05-13 | E-MEXP-2172 | biostudies-arrayexpress
Project description:Meiotic recombination is of central importance for the proper segregation of homologous chromosomes and is initiated by DNA double-strand breaks (DSB) that depend on Spo11 and Mre11. Calibrated chromatin immunoprecipitation (ChIP) for Mre11 shows that Spo11 promotes Mre11 recruitment to chromatin, independent of DSB formation. A C-terminal deletion mutant deficient in Spo11 interaction severely reduces the association of Mre11 with meiotic chromatin. Consistent with the reduction of Mre11 foci in this mutant, it strongly impedes DSB formation, leading to spore death.
2024-01-25 | GSE253302 | GEO
Project description:Gene amplification, copy-number increases of particular genes and surrounding genomic segments, promotes cancer progression and acquired therapy resistance. Thus, understanding genetic traits that confer gene amplification proficiency is important. The primary step for gene amplification is spontaneous DNA rearrangements initiated by DNA breaks. Here we show that mammalian cells became gene amplification-proficient when we knocked down Mre11/Rad50/Nbs1 (MRN) complex, a multifunctional complex that guards the genome from DNA breaks. Cells with reduced Mre11 experienced severe replication stress, with marked increases of single-stranded breaks followed by double-stranded breaks during DNA replication. Such breaks underlay for the increase in spontaneous gene amplification. Other traits associated with replication stress, such as impaired intra-S phase checkpoint and global transcriptional changes in DNA metabolism genes also contributed to gene amplification proficiency. Our results define Mre11 deficiency as a cause of replication stress and gene amplification proficiency and provide a candidate marker for aggressive cancer phenotypes.
2015-03-05 | GSE59487 | GEO
Project description:Understanding the molecular underpinnings of pluripotency is a prerequisite for optimal maintenance and application of embryonic stem cells (ESCs). While the protein-protein interactions of core pluripotency factors have been identified in mouse ESCs, their interactome in human ESCs (hESCs) has not to date been explored. Here we mapped the OCT4 interactomes in naïve and primed hESCs, revealing extensive connections to mammalian ATP-dependent nucleosome remodeling complexes.
2021-09-12 | PXD026556 | Pride