The m6A reader IGF2BP2 promotes homologous recombination-mediated DNA repair by eliminating DNA-RNA hybrids
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo Sapiens
SUBMITTER: 
Yang Li
PROVIDER: PXD067817 | iProX | Thu Aug 28 00:00:00 BST 2025
REPOSITORIES: iProX
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Project description:Class Switch Recombination (CSR) is a B cell specific genomic alteration induced by activation induced cytidine deaminase (AID)-dependent DNA break, followed by repair and recombination at the immunoglobulin heavy-chain locus. The involvement of several chromatin-associated factors in promoting AID-induced DNA break formation has been reported. However, the involvement of chromatin adaptors at the repair phase of CSR remains unknown. Here, we provide evidence that acetylated histone reader Brd4 is critical to the repair and recombination step of CSR. Brd4 was recruited to the AID-induced DNA break region, and depletion of Brd4 from the S region chromatin by knockdown or a chemical inhibitor JQ1 causes CSR impairment without affecting AID-induced DNA break generation. Such inhibition of Brd4 suppressed the accumulation of 53BP1 and UNG at the cleaved S regions, perturbed switch donor-switch acceptor microhomology length and reduced Igh/c-myc translocation. We conclude that Brd4 serves as a histone-reader platform required for the recruitment of CSR repair components. Brd4 were depleted from the chromatin by either siRNA treatment or JQ1 (40nM) addition in CH12F3-2A cells in the presence of CIT stimulation. RNA from each samples were extracted and relative difference in transcript level were compared with control RNAi- and DMSO-treated, CIT-stimulated samples.
2014-06-20 | E-GEOD-52239 | biostudies-arrayexpress
Project description:Class Switch Recombination (CSR) is a B cell specific genomic alteration induced by activation induced cytidine deaminase (AID)-dependent DNA break, followed by repair and recombination at the immunoglobulin heavy-chain locus. The involvement of several chromatin-associated factors in promoting AID-induced DNA break formation has been reported. However, the involvement of chromatin adaptors at the repair phase of CSR remains unknown. Here, we provide evidence that acetylated histone reader Brd4 is critical to the repair and recombination step of CSR. Brd4 was recruited to the AID-induced DNA break region, and depletion of Brd4 from the S region chromatin by knockdown or a chemical inhibitor JQ1 causes CSR impairment without affecting AID-induced DNA break generation. Such inhibition of Brd4 suppressed the accumulation of 53BP1 and UNG at the cleaved S regions, perturbed switch donor-switch acceptor microhomology length and reduced Igh/c-myc translocation. We conclude that Brd4 serves as a histone-reader platform required for the recruitment of CSR repair components.
2014-06-20 | GSE52239 | GEO
Project description:DNA–RNA hybrids triggered by double-strand breaks (DSBs) are crucial intermediates during DSB repair, and their timely resolution requires numbers of RNA helicases, including DEAD box 1 (DDX1). However, how these helicases are recruited to DSB-induced hybrids in time remains largely unclear. Here, we revealed that squamous cell carcinoma antigen recognized by T cells 3 (SART3) promotes DDX1 binding to DNA–RNA hybrids at DSBs for optimal homologous recombination (HR) repair. SART3 itself can associate with DNA–RNA hybrids and PAR chains, and is recruited to DSBs in both PARylation- and hybrid-dependent fashion. SART3 also associates with DDX1 and is necessary for DDX1 enrichment at DSBs. The defective SART3-DDX1 association observed in cells expressing the cancer-associated variant SART3-R836W not only abrogates the accumulation of DDX1 at DSBs, but also impairs hybrid removal and HR efficiency, leading to hypersensitivity of tumor cells to drug treatments. Interestingly, beyond impairing hybrid removal through DDX1, SART3 loss also inhibits DNA end resection, causing a more profound DSB repair defect and chemosensitivity. The stimulatory role of SART3 in end resection is mediated by its function to enhance USP15-BARD1 association and BRCA1-BARD1 retention. Together, our study reveals a previously unknown role of SART3 in DSB repair, rendering SART3 a promising target for cancer therapy.
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Project description:Homologous recombination (HR) mediates the error-free repair of DNA double-strand breaks to maintain genomic stability. Here we characterize C17orf53/MCM8IP, an OB-fold containing protein that binds ssDNA, as a DNA repair factor involved in HR. MCM8IP-deficient cells exhibit HR defects, especially in long-tract gene conversion, occurring downstream of RAD51 loading, consistent with a role for MCM8IP in HR-dependent DNA synthesis. Moreover, loss of MCM8IP confers cellular sensitivity to crosslinking agents and PARP inhibition. Importantly, we report that MCM8IP directly associates with MCM8-9, a helicase complex mutated in primary ovarian insufficiency, and RPA1. We additionally show that the interactions of MCM8IP with MCM8-9 and RPA facilitate HR and promote replication fork progression and cellular viability in response to treatment with crosslinking agents. Mechanistically, MCM8IP stimulates the helicase activity of MCM8-9. Collectively, our work identifies MCM8IP as a key regulator of DNA damage-associated DNA synthesis during DNA recombination and replication.
2020-06-15 | PXD019156 | Pride
Project description:The N6-methyladenosine (m6A) is the most abundant internal modification in almost all eukaryotic messenger RNAs, and is dynamically regulated. Therefore, identification of m6A readers is especially important in determining the cellular function of m6A. YTHDF2 has recently been characterized as the first m6A reader that regulates the cytoplasmic stability of methylated RNA. Here we show that YTHDC1 is a nuclear m6A reader and report the crystal structure of the YTH domain of YTHDC1 bound to m6A-containing RNA. We further determined the structure of another YTH domain, YTHDF1, and found that the YTH domain utilizes a conserved aromatic cage to specifically recognize the methyl group of m6A. Our structural characterizations of the YTHDC1-m6A RNA complex also shed light on the molecular basis for the preferential binding of the GG(m6A)C sequence by YTHDC1 and confirm the YTH domain as a specific m6A RNA reader. PAR-CLIP (Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation) was applied to human YTHDC1 protein to identify its binding sites.
2014-09-18 | E-GEOD-58352 | biostudies-arrayexpress
Project description:The BRCA2 tumor suppressor is a DNA double-strand break repair factor essential to maintain genome integrity. BRCA2-deficient cells spontaneously accumulate DNA-RNA hybrids, a known source of genome instability. However, the specific role of BRCA2 on these structures remains poorly understood. Here we identified the DEAD-box RNA helicase DDX5 as a BRCA2 interacting partner. We show that DDX5 associates with DNA-RNA hybrids that form in the vicinity of DSBs and this association is enhanced by BRCA2. Notably, BRCA2 stimulates the DNA-RNA hybrid helicase activity of DDX5. Impaired BRCA2-DDX5 interaction, as observed in cells bearing the breast cancer variant BRCA2-T207A, reduces DDX5 association with DSBs, decreases the number of RPA foci upon irradiation and impairs RAD51 repair foci formation. Our findings are consistent with DNA-RNA hybrids being an impediment for the repair of DSBs by homologous recombination and reveal BRCA2 and DDX5 as active players in their removal.
2021-02-26 | GSE150163 | GEO
Project description:RNA:DNA hybrids accumulate at the vicinity of DNA double-strand breaks (DSBs) and were shown to regulate homologous recombination repair. The mechanism responsible for the formation of these non-canonical RNA:DNA structures remains unclear although they were proposed to arise consequently to RNA Polymerase II or III loading followed by DSB-induced de novo transcription at the break site. Here, we found no evidence of RNA polymerases recruitment at DSBs. Rather, strand-specific R-loop mapping revealed that RNA:DNA hybrids are mainly generated at DSBs occurring in transcribing loci, from the hybridization of pre-existing RNA to the 3’ overhang left by DNA end resection. We further identified the H3K4me3 reader Spindlin 1 and the transcriptional regulator PAF1 as promoting RNA:DNA hybrid accumulation at DSBs, through their role in mediating transcriptional repression in cis to DSBs. Altogether, we provide evidence that RNA:DNA hybrids accumulate at DSBs occurring in transcribing loci as a result of DSB-induced transcriptional shut-down.
2025-03-30 | E-MTAB-13197 | biostudies-arrayexpress
Project description:Class Switch Recombination (CSR) is a DNA recombination reaction that diversifies the effector component of antibody responses. CSR is initiated by activation-induced cytidine deaminase (AID), which targets transcriptionally active immunoglobulin heavy chain (Igh) switch donor and acceptor DNA. The 3’ Igh super-enhancer, 3’ Regulatory Region (3’RR), is essential for acceptor region transcription, but how this function is regulated is unknown. Here we identify the chromatin reader ZMYND8 as an essential regulator of the 3’RR and CSR. In B cells, ZMYND8 binds promoters and super-enhancers, including the 3’RR, and controls its activity by modulating the enhancer transcriptional status. In its absence, there is increased 3’RR polymerase loading, and decreased acceptor region transcription and CSR. In addition to CSR, ZMYND8 deficiency impairs somatic hypermutation (SHM) of Igh, which is also dependent on the 3’RR. Thus ZMYND8 controls Igh diversification in mature B lymphocytes by regulating the activity of the 3’ Igh super-enhancer.
2018-10-04 | GSE118794 | GEO
Project description:Meiotic recombination is required for the segregation of homologous chromosomes and is essential for fertility. The DNA double strand breaks (DSBs) that initiate meiotic recombination are directed by sequence-specific DNA binding of the PRDM9 protein. Gradual elimination of PRDM9 binding sites by gene conversion is thought to result in the hotspot erosion while mutations affecting DNA binding specificity of PRDM9 will create the new sets of hotspots. To better understand evolutionary turnover of recombination hotspots we mapped DSB hotspots in six inbred mouse strains representing all four major subspecies of Mus musculus and in their F1 hybrids. We found that hotspot erosion governs the preferential usage of some Prdm9 alleles over others in hybrid mice and increases sequence diversity specifically at hotspots that become active in the hybrids. As crossovers are disfavored at such hotspots, we propose that sequence divergence generated by hotspot turnover creates impediments for recombination in hybrids, potentially leading to reduction in fertility and eventually, speciation.
2016-02-03 | GSE75419 | GEO
Project description:R-loops, which consist of a DNA/RNA hybrid and a displaced single-stranded DNA (ssDNA), are increasingly recognized as critical regulators of chromatin biology. R-loops are particularly enriched at gene promoters, where they play important roles in regulating gene expression. However, the molecular mechanisms that control promoter-associated R-loops remain unclear. The epigenetic “reader” Tudor domain-containing protein 3 (TDRD3), which recognizes methylarginine marks on histones and on the C-terminal domain of RNA polymerase II, was previously shown to recruit DNA topoisomerase 3B (TOP3B) to relax negatively supercoiled DNA and prevent R-loop formation. Here, we further characterize the function of TDRD3 in R-loop metabolism and introduce the DExH-box helicase 9 (DHX9) as a novel interaction partner of the TDRD3/TOP3B complex. TDRD3 directly interacts with DHX9 via its Tudor domain. This interaction is important for recruiting DHX9 to target gene promoters, where it resolves R-loops in a helicase activity-dependent manner to facilitate gene expression. Additionally, TDRD3 also stimulates the helicase activity of DHX9. This stimulation relies on the OB-fold of TDRD3, which likely binds the ssDNA in the R-loop structure. Thus, DHX9 functions together with TOP3B to suppress promoter-associated R-loops. Collectively, these findings reveal new functions of TDRD3 and provide important mechanistic insights into the regulation of R-loop metabolism.
2021-06-26 | GSE178905 | GEO