NFKB2 Knockdown Reduces Expression of HR-Related Genes
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE148511 | GEO | 2022/06/07
REPOSITORIES: GEO
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Project description:Expression of RAD51, a crucial player in homologous recombination (HR) and DNA double-strand break (DSB) repair, is dysregulated in human tumors, and can contribute to genomic instability and tumor progression. To further understand RAD51 regulation we functionally characterized a long non-coding (lnc) RNA, AK125393, dubbed TODRA (Transcribed in the Opposite Direction of RAD51), transcribed 69bp upstream to RAD51, in the opposite direction. TODRA overexpression in HeLa cells induced expression of TPIP, a member of the TPTE family which includes PTEN. Similar to PTEN, we found that TPIP co-activates E2F1 induction of RAD51.
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Project description:The alternative (non-canonical) nuclear factor-kappa B (NF-κB) signalling pathway predominantly regulates the function of the p52/RelB heterodimer. Germline Nfkb2 deficiency in mice leads to loss of p100/p52 protein and offers protection against a variety of gastrointestinal conditions, such as azoxymethane/dextran sulfate sodium (DSS)-induced colitis-associated cancer and lipopolysaccharide (LPS)-induced small intestinal epithelial apoptosis. However, the common underlying protective mechanisms are not yet fully understood. Here we applied RNA sequencing and identified a B-lymphocyte defect as the major signature in the small intestinal mucosa of naïve adult Nfkb2-/- mice. Proteomics analysis also revealed a dramatic decrease in small intestinal immunoglobulin A levels, and this was validated by quantitative ELISA in both small intestinal lysates and serum. Moreover, the numbers of IgA-producing, CD138+ve plasma cells were also reduced in the lamina propria of the small intestinal villi of Nfkb2-/- mice. This phenotype was even more striking in the small intestinal mucosa of RelB-/- mice, although these mice were equally sensitive to LPS-induced intestinal apoptosis as their RelB+/+ wild-type counterparts. Therefore, p52 deficiency offers resistance to LPS-induced intestinal apoptosis and appears to regulate the plasma cell population within the gut.
2022-07-31 | E-MTAB-11018 | biostudies-arrayexpress
Project description:DNA double-strand breaks (DSBs) are a prominent source of genetic instability/variability frequently associating genome rearrangements with the capture of ectopic chromosomal sequences (ECSs) at junctions. Homologous recombination (HR) is considered in textbooks as an error-free DSB repair mechanism that protects against genome instability. Contradicting this dogma, we show that silencing the central HR players RAD51 or BRCA2 suppresses the sequence homology-independent capture of ECS at the junctions of distant DSBs, especially in 53BP1-depleted cells. We confirmed the requirement of RAD51 for ECS capture at a genome-wide level through high-throughput genome translocation sequencing.
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Project description:RAD51 protein is an evolutionarily conserved recombinase that plays a central role in homologous recombination (HR) and DNA double strand break (DSB) repair. RAD51 inactivation by small molecules has been proposed as a strategy to impair the BRCA2/RAD51 binding and, ultimately, the HR pathway, with the aim to make cancer cells more sensitive to PARP inhibitors (PARPi). This strategy, which mimics a synthetic lethality (SL) approach, has been successfully assayed in vitro by using myr-BRC4, a peptide derived from the fourth BRC repeat of BRCA2, being the strongest reported natural RAD51 binder. The present study applies a method to obtain a proteomic fingerprint for RAD51 inhibition by the myr-BRC4 peptide (designed for a more efficient cell entry) using a mass spectroscopy (MS) proteomic approach. We performed a comparative proteomic profiling of the myr-BRC4 treated vs. untreated BxPC-3 pancreatic cancer cells and evaluated the differential expression of proteins. Among the identified proteomic hits, we focused our attention on proteins shared by both the RAD51 and the BRCA2 interactomes, and on those whose reduction showed high statistical significance. Three downregulated proteins were identified (FANCI, FANCD2, and RPA3) and protein downregulation was confirmed through immunoblotting analysis, validating the MS approach. Our results suggest that, being a direct consequence of RAD51 inhibition, the detection of FANCD2, FANCI, and RPA3 downregulation could be used as an indicator for monitoring HR impairment.
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Project description:Expression of RAD51, a crucial player in homologous recombination (HR) and DNA double-strand break (DSB) repair, is dysregulated in human tumors, and can contribute to genomic instability and tumor progression. To further understand RAD51 regulation we functionally characterized a long non-coding (lnc) RNA, AK125393, dubbed TODRA (Transcribed in the Opposite Direction of RAD51), transcribed 69bp upstream to RAD51, in the opposite direction. TODRA overexpression in HeLa cells induced expression of TPIP, a member of the TPTE family which includes PTEN. Similar to PTEN, we found that TPIP co-activates E2F1 induction of RAD51. HeLa cells were transfected with either an empty vector or an AK1253893 minigene. RNA was extracted from duplicates of each experiment and hybridized to affymetrix microarray.
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Project description:Cells have developed effective mechanisms, namely homologous recombination (HR) and non-homologous end-joining (NHEJ), to repair DNA double-strand breaks (DSBs), which are considered to be the most deleterious type of damage that can challenge genome integrity. While these pathways coexist to repair DSBs, the mechanisms by which one of these pathways is chosen to repair a particular DSB remain unclear. Here, we show that the chromatin context in which a break occurs participates in this choice and that transcriptionnaly active chromatin channels repair to HR. By using a human cell line expressing a restriction enzyme fused to the ligand binding domain of the oestrogen receptor (AsiSI-ER)2,3, together with a genome wide chromatin immunoprecipitation-sequencing (ChIP-seq) approach, we establish that distinct DSBs induced across the genome are not necessarily repaired by the same pathway. Indeed, we identify an HR-prone subset of DSBs that recruit the HR protein RAD51, undergo resection, and rely on RAD51 for efficient repair. These DSBs are located in actively transcribed genes, and repair at such DSBs can be switched to RAD51-independent repair pathway upon transcriptional inhibition. Moreover, we show that HR is targeted to transcribed loci thanks to the elongation-associated H3K36me3 histone mark. Indeed depletion of HYPB, the main H3K36 tri methyltransferase severally impedes the use of HR at those DSBs. Our study, thereby demonstrates a clear role for chromatin in DSB repair pathway choice in human cells.
2014-03-23 | E-MTAB-1241 | biostudies-arrayexpress
Project description:Mutations in the tumour suppressor BRCA2 are associated with predisposition to breast and ovarian cancers. BRCA2 has a central role in genome integrity by facilitating the repair of toxic DNA double-strand breaks (DSBs) by homologous recombination. BRCA2 acts by promoting RAD51 nucleofilament formation on resected single-stranded DNA, but how BRCA2 activity is regulated during HR is not fully understood. Here, we delineate a pathway where ATM and ATR kinases phosphorylate a highly conserved region in BRCA2 in response to DNA DSBs. These phosphorylations stimulate the binding of the protein phosphatase PP2A-B56 to BRCA2 through a conserved binding motif. We show that the phosphorylation-dependent formation of the BRCA2-PP2A-B56 complex is required for efficient RAD51 loading to sites of DNA damage and HR-mediated DNA repair. Moreover, we find that several cancer-associated mutations in BRCA2 deregulate the BRCA2-PP2A-B56 interaction and sensitize cells to PARP inhibition. Collectively, our work uncovers PP2A-B56 as a positive regulator of BRCA2 function in HR with clinical implications for BRCA2 and PP2A-B56 mutated cancers.
2021-07-26 | MSV000087884 | MassIVE
Project description:Homologous recombination (HR) plays an essential role in the maintenance of genome stability by promoting the repair of cytotoxic DNA double strand breaks (DSBs). More recently, the HR pathway has emerged as an integral component of the response to replication stress, in part by protecting stalled replication forks from nucleolytic degradation. In that regard, the mammalian RAD51 paralogs (RAD51B, RAD51C, RAD51D, XRCC2, and XRCC3) have been involved in both HR-mediated DNA repair and collapsed replication fork resolution. Still, it remains largely obscure how they participate in both processes, thereby maintaining genome stability and preventing cancer development. To gain better insight into their contribution in cellulo, we mapped the proximal interactome of the classical RAD51 paralogs using the BioID approach. Aside from identifying the well-established BCDX2 and CX3 sub-complexes, the spliceosome machinery emerged as an integral component of our proximal mapping, suggesting a crosstalk between this pathway and the RAD51 paralogs. Furthermore, we noticed that factors involved RNA metabolic pathways are significantly modulated within the BioID of the classical RAD51 paralogs upon exposure to hydroxyurea (HU), pointing towards a direct contribution of RNA processing during replication stress. Importantly, several members of these pathways have prognosis potential in breast cancer (BC), where their RNA expression correlates with poorer patient outcome. Collectively, this study uncovers novel functionally relevant partners of the different RAD51 paralogs in the maintenance of genome stability and could be used as biomarker for the prognosis of BC.
2022-05-20 | MSV000089507 | MassIVE
Project description:Ubiquitination is a crucial post-translational modification required for the proper repair of DNA double-strand breaks (DSBs) induced by ionising radiation (IR). DSBs are mainly repaired through homologous recombination (HR) when template DNA is present and non-homologous end joining (NHEJ) in its absence. Additionally, microhomology-mediated end joining (MMEJ) and single strand annealing (SSA) provide back-up DSBs repair pathways. However, the mechanisms controlling their use remain poorly understood. By employing a high-resolution CRISPR screen of the ubiquitin system after IR, we systematically uncover genes required for cell survival and elucidate a critical role of the E3 ubiquitin ligase SCFcyclin F in cell cycle dependent DSB repair. We show that SCFcyclin F -mediated EXO1 degradation prevents DNA end resection in mitosis, allowing MMEJ to take place. Moreover, we identify a conserved cyclin F recognition motif, distinct from the one used by other cyclins, with broad implications in cyclin specificity for cell cycle control.
2024-10-17 | PXD051841 | Pride
Project description:Homologous recombination (HR) and nucleotide excision repair (NER) are the two most frequently disabled DNA repair pathways in cancer. HR-deficient breast, ovarian, pancreatic and prostate cancers respond well to platinum chemotherapy and PARP inhibitors. However, the frequency of HR deficiency in gastric and esophageal adenocarcinoma (GEA) still lacks diagnostic and functional validation. Using whole exome and genome sequencing data, we found that a significant subset of GEA, but very few colorectal adenocarcinomas, show evidence of HR deficiency by mutational signature analysis (HRD score). High HRD gastric cancer cell lines demonstrated functional HR deficiency by RAD51 foci assay and increased sensitivity to platinum chemotherapy and PARP inhibitors. Of clinical relevance, analysis of three different GEA patient cohorts demonstrated that platinum treated HR deficient cancers had better outcomes. A gastric cancer cell line with strong sensitivity to cisplatin showed HR proficiency but exhibited NER deficiency by two photoproduct repair assays. Single-cell RNA-sequencing revealed that, in addition to inducing apoptosis, cisplatin treatment triggered ferroptosis in a NER-deficient gastric cancer, validated by intracellular GSH assay. Overall, our study provides preclinical evidence that a subset of GEAs harbor genomic features of HR and NER deficiency and may therefore benefit from platinum chemotherapy and PARP inhibitors.
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