Histone variant macroH2A1.1 enhances non-homologous end joining-dependent DNA double-strand-break repair and reprogramming efficiency of human iPSC
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ABSTRACT:
PROVIDER: PRJNA690535 | ENA |
REPOSITORIES: ENA
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Project description:Here we used RNA-Seq to gain deep mechanistic insight into the effects of macroH2A1 splicing isoforms macroH2A1.1 and macroH2A1.2 on Human Umbelical Vein Endothelial Cells (HUVEC) undergoing cell reprogramming. The process was triggered using an episome construct carrying the reprogramming factors Oct4, Sox2, Klf4, L-Myc and Lin28. RNA-seq analysis was performed on the fourth day of the reprogramming process, to investigate the role. Heatmap anlysis of top 44 differently expressed genes (DEG) revealed that macroH2A1.1, but not macroH2A1.2,increased the expression of genes involved in DNA repair response (DDR) and cell reprogramming in HUVEC. Genes exhibiting absolute fold-change values >2 and p-values <0.05 were considered differentially expressed between contrasts. Statistical differences in gene expression were assessed by the ANOVA test. Correction for multiple test was achieved by the Benjamini-Hochberg procedure. The significance threshold was set to 0.05. Ingenuity pathway analysis (IPA) identified differences in evaluating top 44 DEG involved in DDR and top 12 DEG involved in cell reprogramming showed that macroH2A1.1 verexpression enhances several pathways involved in DNa repair and acquisition of cell pluripotency.
2021-01-08 | GSE164396 | GEO
Project description:IgH class switch recombination (CSR) in B lymphocytes switches IgH constant regions to change antibody functions. CSR is initiated by DNA double strand breaks (DSBs) within a donor IgH switch (S) region and a downstream acceptor S region. CSR is completed by fusing donor and acceptor S region DSB ends by classical non-homologous end-joining (C-NHEJ) and, in its absence, by alternative end-joining (A-EJ) that is more biased to use longer junctional micro-homologies (MHs). Deficiency for DSB response (DSBR) factors, including ATM and 53BP1, variably impair CSR end-joining, with 53BP1 deficiency having the greatest impact. However, studies of potential impact of DSBR factor deficiencies on MH-mediated CSR end-joining have been technically limited. We now use a robust DSB joining assay to elucidate impacts of deficiencies for DSBR factors on CSR and chromosomal translocation junctions in primary mouse B cells and CH12F3 B lymphoma cells. Compared to wild-type, CSR and c-Myc to S region translocation junctions in the absence of 53BP1, and to a lesser extent other DSBR factors, have increased MH-utilization; indeed, 53BP1-deficient MH-profiles resemble those associated with C-NHEJ deficiency. Yet, translocation junctions between c-Myc DSB and general DSBs genome-wide are not MH-biased in ATM-deficient versus wild-type CH12F3 cells and less biased in 53BP1- and C-NHEJ-deficient cells than CSR junctions or c-Myc to S region translocation junctions. We discuss potential roles of DSBR factors in suppressing increased MH-mediated DSB end-joining and features of S regions that may render their DSBs prone to MH-biased end-joining in the absence of DSBR factors.
2018-01-08 | GSE106922 | 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:Successful R-loop homeostasis consists of its timely biogenesis and removal throughout the genome to regulate diverse cellular processes. Yet, they are considered hazardous source to our genome when their turnover goes awry. Here, we report HELZ, a novel player in R-loop homeostasis and DNA repair pathway. HELZ mediates resistance to several DNA damaging agents, and localizes to DSBs and its depletion increases R-loops fostering genomic instability. Loss of HELZ results in impaired homologous recombination (HR) due to R-loops accumulation, with an increase in classical-non-homologous end joining (c-NHEJ), suggesting a role for HELZ in regulating DSB repair pathway choice. Rad51 retention at DSBs is governed by HELZ mediated R-loop accumulation. Mechanistically, our data show that HELZ complexes with BRCA1 and facilitates its recruitment to DSBs in an R-loop dependent manner. Collectively, our data support a model in which HELZ recruits BRCA1 and facilitates R loop resolution at DSBs to promote HR and therefore maintains genome stability.
2023-11-01 | GSE242527 | GEO
Project description:The DNA damage response (DDR) is the signaling cascade that recognizes DNA double-strand breaks (DSB) and promotes their resolution via the DNA repair pathways of Non-Homologous End Joining (NHEJ) or Homologous Recombination (HR). We and others have shown that DDR activation requires DROSHA. However, whether DROSHA exerts its functions by associating with damage sites, what controls its recruitment and how DROSHA influences DNA repair, remains poorly understood. Here we show that DROSHA associates to DSBs independently from transcription. Neither H2AX, nor ATM nor DNA-PK kinase activities are required for its recruitment to break site. Rather, DROSHA interacts with RAD50 and inhibition of MRN by Mirin treatment abolishes this interaction. MRN inactivation by RAD50 knockdown or mirin treatment prevents DROSHA recruitment to DSB and, as a consequence, also 53BP1 recruitment. During DNA repair, DROSHA inactivation reduces NHEJ and boosts HR frequency. Indeed, DROSHA knockdown also increase the association of downstream HR factors such as RAD51 to DNA ends. Overall, our results demonstrate that DROSHA is recruited at DSBs by the MRN complex and direct DNA repair toward NHEJ.
2021-03-15 | GSE166631 | GEO
Project description:Insertions and deletions (indels) are common sources of structural variation, and insertions originating from spontaneous DNA lesions are frequent in cancer. We developed a highly sensitive assay (Indel-Seq) to monitor rearrangements in human cells at the TRIM37 acceptor locus that reports indels stemming from experimentallyinduced and spontaneous genome instability. Templated insertions, which derive from sequences genome-wide, require contact between donor and acceptor loci, homologous recombination, and are stimulated by DNA end-processing. Insertions are facilitated by transcription and involve a DNA/RNA hybrid intermediate. Indel-Seq reveals that insertions are generated via multiple pathways. The broken acceptor site anneals with a resected DNA break or invades the displaced strand of a transcription bubble or R-loop followed by DNA synthesis, displacement and then ligation by nonhomologous end-joining. Our studies identify transcription-coupled insertions as a critical source of spontaneous genome instability that are distinct from cut-and-paste events
2023-07-03 | GSE234089 | GEO
Project description:Determining the balance between DNA double strand break repair (DSBR) pathways is essential for understanding treatment response in cancer. We report a novel method for simultaneously measuring non-homologous end joining (NHEJ), homologous recombination (HR), and microhomology-mediated end joining (MMEJ). This approach revealed enhanced MMEJ and HR in glioblastoma (GBM) xenograft models with acquired temozolomide (TMZ) resistance. Knockdown of proteins in either pathway enhanced killing by TMZ, and a targeted screen identified pharmacological-grade dual HR/MMEJ inhibitors, including AZD1390, an ATM kinase inhibitor. AZD1390 suppressed DSB end resection, blocked phosphorylation of end protection proteins in response to DNA damage, and potentiated TMZ in treatment-naïve and treatment-resistant models. TP53-mutant GBMs were most susceptible to AZD1390 in combination with DNA-damaging agents due to elevated ATM-dependent HR/MMEJ, preferential activation of these pathways in response to DNA damage, and a defective G2/M checkpoint, which caused these GBMs to enter mitosis despite unrepaired DNA damage, leading to cell death via apoptosis. This report establishes ATM-dependent HR and MMEJ as targetable resistance mechanisms in TP53-mutant GBM and establishes an approach for simultaneously measuring multiple DSBR pathways in treatment selection and oncology research.
2024-03-08 | PXD047837 | Pride
Project description:RIF1 acts downstream of 53BP1 to coordinate DNA double strand break repair pathway choice between non-homologous end joining (NHEJ) and homologous recombination (HR). Here we identified ASF1 as an endogenous RIF1-associated protein. We showed that ASF1 forms complex with RIF1 and regulates RIF1-dependent functions in DNA damage response.
2022-06-09 | PXD027727 | Pride
Project description:The yeast cyclic-AMP dependent protein kinase A (PKA) is a ubiquitous serine-threonine kinase, encompassing three catalytic (Tpk1-3) and one regulatory (Bcy1) subunits. Evidence suggests PKA involvement in DNA damage checkpoint response, but how DNA repair pathways are regulated by PKA subunits remains inconclusive. Here, we report that deleting the catalytic subunit, tpk1, reduces non-homologous end joining (NHEJ) efficiency, whereas tpk2-3 and bcy1 deletion does not. Epistatic analyses revealed that tpk1, as well as the DNA damage checkpoint kinase (dun1) and NHEJ regulator (nej1), co-function in the same pathway. Chromatin immunoprecipitation and resection data suggest that the recruitment of repair proteins and DNA resection is influenced by tpk1 deletion. Further, we show that Tpk1 phosphorylation of Nej1 at S298 (a Dun1 phosphosite) is indispensable for NHEJ repair, in addition to nuclear targeting of Nej1 and its binding partner Lif1. In mammalian cells, loss of PRKACB (the human homolog of Tpk1) also reduced NHEJ efficiency, and similarly, PRKACB was found to phosphorylate XLF (a Nej1 human homolog) at S263, a corresponding residue of the yeast Nej1 S298. Together, our results uncover a new and conserved mechanism for Tpk1 and PRKACB in phosphorylating Nej1 (or XLF), which is critically required for NHEJ repair.
2021-09-10 | PXD024695 | Pride
Project description:The yeast cyclic-AMP dependent protein kinase A (PKA) is a ubiquitous serine-threonine kinase, encompassing three catalytic (Tpk1-3) and one regulatory (Bcy1) subunits. Evidence suggests PKA involvement in DNA damage checkpoint response, but how DNA repair pathways are regulated by PKA subunits remains inconclusive. Here, we report that deleting the catalytic subunit, tpk1, reduces non-homologous end joining (NHEJ) efficiency, whereas tpk2-3 and bcy1 deletion does not. Epistatic analyses revealed that tpk1, as well as the DNA damage checkpoint kinase (dun1) and NHEJ regulator (nej1), co-function in the same pathway. Chromatin immunoprecipitation and resection data suggest that the recruitment of repair proteins and DNA resection is influenced by tpk1 deletion. Further, we show that Tpk1 phosphorylation of Nej1 at S298 (a Dun1 phosphosite) is indispensable for NHEJ repair, in addition to nuclear targeting of Nej1 and its binding partner Lif1. In mammalian cells, loss of PRKACB (the human homolog of Tpk1) also reduced NHEJ efficiency, and similarly, PRKACB was found to phosphorylate XLF (a Nej1 human homolog) at S263, a corresponding residue of the yeast Nej1 S298. Together, our results uncover a new and conserved mechanism for Tpk1 and PRKACB in phosphorylating Nej1 (or XLF), which is critically required for NHEJ repair.
2021-09-10 | PXD024768 | Pride