R-loop editing by DNA cytosine deaminase APOBEC3B determines activities of estrogen receptor enhancers.
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ABSTRACT:
PROVIDER: PRJNA795957 | ENA |
REPOSITORIES: ENA
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Project description:The single-stranded DNA cytosine-to-uracil deaminase APOBEC3B is an antiviral protein implicated in cancer. However, its substrates in cells are not fully delineated. Here, APOBEC3B proteomics reveal interactions with a surprising number of R-loop factors. Biochemical experiments show APOBEC3B binding to R-loops in human cells and in vitro. Genetic experiments demonstrate R-loop increases in cells lacking APOBEC3B and decreases in cells overexpressing APOBEC3B. Genome-wide analyses show major changes in the overall landscape of physiological and stimulus-induced R-loops with thousands of differentially altered regions as well as binding of APOBEC3B to many of these sites. APOBEC3 mutagenesis impacts overexpressed genes and splice factor mutant tumors preferentially, and APOBEC3-attributed kataegis are enriched in RTCW consistent with APOBEC3B deamination. Taken together with the fact that APOBEC3B binds single-stranded DNA and RNA and preferentially deaminates DNA, these results support a mechanism in which APOBEC3B mediates R-loop homeostasis and contributes to R-loop mutagenesis in cancer.
2023-06-10 | GSE148581 | GEO
Project description:R-loop homeostasis and cancer mutagenesis promoted by the DNA cytosine deaminase APOBEC3B
| PRJNA625079 | ENA
Project description:This SuperSeries is composed of the SubSeries listed below.
2025-01-06 | GSE193234 | GEO
Project description:Mutations in cancer are due in part to DNA cytosine deamination by APOBEC3B (A3B). While low in healthy tissues, A3B expression and activity are elevated in tumors and further increase in metastases. However, molecular mechanisms responsible for A3B transcriptional regulation are poorly understood. Here, we address whether the RB/E2F pathway, which is often dysregulated in breast cancer, is a molecular trigger of A3B overexpression. First, an A3B promoter-driven luciferase reporter was used to demonstrate reporter activation by disruption of only one out of five predicted E2F binding sites. Second, A3B-luciferase reporter activation was also triggered by expressing the BK polyomavirus T-antigen, which inactivates RB and thereby alleviates repression of E2F regulated genes. Importantly, A3B-luciferase reporter induction by BK polyomavirus T-antigen could not be further increased by mutating the functional E2F binding site. Third, both CRISPR disruption and targeted base substitutions in the endogenous E2F binding site caused strong A3B upregulation and confirmed importance of this regulatory element. Fourth, proteomics experiments showed that members of the DREAM and PRC1.6-complexes including multiple E2F family members are able to bind to wild-type but not E2F mutant promoter sequences. Finally, a combination of genetic and biochemical studies implicated E2F4 and E2F6 in endogenous A3B gene repression. Altogether, our studies demonstrate that A3B expression is suppressed in normal cells by the RB/E2F axis and that viral or mutational disruption of this pathway causes overexpression of this DNA deaminase in cancer and contributes mutational fuel to tumor evolution.
2020-10-19 | PXD020473 | Pride
Project description:A conditional and isogenic system for APOBEC3B (A3B) induction in T-REx-293 cells. Cells were engineered to express doxycycline-inducible A3B-eGFP or eGFP constructs and subjected to 10 rounds of A3B-eGFP exposure causing 80-90% cell death. Control pools (eGFP) were subjected to parallel rounds of non-toxic eGFP exposure, and dilutions were done each round to mimic A3B-eGFP induced population fluctuations. DNA was extracted and subjected to SNP analyses using the Human OmniExpress-24v1-0 BeadChip (Illumina, San Diego, CA). Genotyping was performed using the humanomniexpress_24v1-0_a cluster file. SNP data is avaiable for a total of 16 samples, all derived from single cells mother lines A and C. For each series, each consisting of 8 samples, A3B-eGFP and eGFP daugther clones were processed on the SNP microarray, as well as 3 A3B-eGFP and 3 eGFP grand-daugther clones.
2016-06-30 | E-GEOD-78710 | biostudies-arrayexpress
Project description:A conditional and isogenic system for APOBEC3B (A3B) induction in T-REx-293 cells. Cells were engineered to express doxycycline-inducible A3B-eGFP or eGFP constructs and subjected to 10 rounds of A3B-eGFP exposure causing 80-90% cell death. Control pools (eGFP) were subjected to parallel rounds of non-toxic eGFP exposure, and dilutions were done each round to mimic A3B-eGFP induced population fluctuations. DNA was extracted and subjected to SNP analyses using the Human OmniExpress-24v1-0 BeadChip (Illumina, San Diego, CA). Genotyping was performed using the humanomniexpress_24v1-0_a cluster file.
2016-06-30 | GSE78710 | GEO
Project description:Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3B) is a key molecular driver inducing mutations in multiple human cancers. APOBEC3B belongs to the APOBEC3 enzyme family, which consists seven closely related DNA deaminases that catalyse cytosine-to-uracil (C>U) editing of single-stranded DNA (ssDNA). In order to investigate the genomic binding sites of APOBEC3B, high through-put sequencing experiments were conducted using DNA samples acquired by standard chromatin immunoprecipitation (ChIP) and ssDNA protein immunoprecipitation (SPI) samples. Substrate preference by APOBEC3B were characterised by comparing these results.
2025-01-06 | GSE193227 | GEO
Project description:CRISPR-guided DNA base editors enable the efficient installation of targeted single-nucleotide changes. Cytosine or adenine base editors (CBEs or ABEs), which are fusions of cytidine or adenosine deaminases to CRISPR-Cas nickases, can efficiently induce DNA C-to-T or A-to-G alterations in DNA, respectively. We recently demonstrated that both the widely used CBE BE3 (harboring a rat APOBEC1 cytidine deaminase) and the optimized ABEmax editor can induce tens of thousands of guide RNA-independent, transcriptome-wide RNA base edits in human cells with high efficiencies. In addition, we showed the feasibility of creating SElective Curbing of Unwanted RNA Editing (SECURE)-BE3 variants that exhibit substantially reduced unwanted RNA editing activities while retaining robust and more precise on-target DNA editing. Here we describe structure-guided engineering of SECURE-ABE variants that not only possess reduced off-target RNA editing with comparable on-target DNA activities but are also the smallest Streptococcus pyogenes Cas9 (SpCas9) base editors described to date. In addition, we tested CBEs composed of cytidine deaminases other than APOBEC1 and found that human APOBEC3A (hA3A) cytidine deaminase CBE induces substantial transcriptome-wide RNA base edits with high efficiencies. By contrast, a previously described “enhanced” A3A (eA3A) cytidine deaminase CBE or a human activation-induced cytidine deaminase (hAID) CBE induce substantially reduced or near background levels of RNA edits. In sum, our work describes broadly useful SECURE-ABE and -CBE base editors and reinforces the importance of minimizing RNA editing activities of DNA base editors for research and therapeutic applications.
2019-07-11 | GSE129893 | GEO
Project description:CRISPR-guided DNA base editors enable the efficient installation of targeted single-nucleotide changes. Cytosine or adenine base editors (CBEs or ABEs), which are fusions of cytidine or adenosine deaminases to CRISPR-Cas nickases, can efficiently induce DNA C-to-T or A-to-G alterations in DNA, respectively. We recently demonstrated that both the widely used CBE BE3 (harboring a rat APOBEC1 cytidine deaminase) and the optimized ABEmax editor can induce tens of thousands of guide RNA-independent, transcriptome-wide RNA base edits in human cells with high efficiencies. In addition, we showed the feasibility of creating SElective Curbing of Unwanted RNA Editing (SECURE)-BE3 variants that exhibit substantially reduced unwanted RNA editing activities while retaining robust and more precise on-target DNA editing. Here we describe structure-guided engineering of SECURE-ABE variants that not only possess reduced off-target RNA editing with comparable on-target DNA activities but are also the smallest Streptococcus pyogenes Cas9 (SpCas9) base editors described to date. In addition, we tested CBEs composed of cytidine deaminases other than APOBEC1 and found that human APOBEC3A (hA3A) cytidine deaminase CBE induces substantial transcriptome-wide RNA base edits with high efficiencies. By contrast, a previously described “enhanced” A3A (eA3A) cytidine deaminase CBE or a human activation-induced cytidine deaminase (hAID) CBE induce substantially reduced or near background levels of RNA edits. In sum, our work describes broadly useful SECURE-ABE and -CBE base editors and reinforces the importance of minimizing RNA editing activities of DNA base editors for research and therapeutic applications.
2019-07-11 | GSE129889 | GEO
Project description:Oestrogen receptor-α (ER) is the principal transcription factor in the majority of breast cancers, driving expression of genes that control cell growth and endocrine response. Understanding the mechanisms of ER action is crucial for improving response to endocrine treatments. Recent studies show that cytosine deaminase (CD) activity is an important source of cancer mutations. In particular, APOBEC3B (A3B) promotes mutagenesis in breast cancer cells1. Our analysis of breast cancer expression datasets showed that A3B expression predicts for poor survival in ER-positive, but not in ER-negative patients, indicative of a link with ER activity. Chromatin immunoprecipitation coupled to deep sequencing (ChIP-seq) used to map global A3B binding sites showed a remarkable oestrogen-stimulated recruitment of A3B to ER binding sites. Functionally, A3B was critical for ER transcriptional activity and regulated breast cancer cell proliferation. We show that A3B regulates ER transcription by promoting cytosine deamination and activation of DNA strand break repair at ER binding regions. We propose that cytosine deamination and DNA strand break generation by A3B facilitates gene expression by aiding chromatin remodeling at ER target genes. Our findings also suggest a mechanism by which subversion of transcription factor mediated recruitment of cytosine deaminases promotes cancer mutations. Hormone-depleted MCF-7 breast cancer cell line was treated with estrogen (100 nM), H2O2 (10 mM) or vehicle for 45 minutes. H2AX ChIP-seq was performed using Illumina methodology.
2015-09-07 | E-GEOD-57426 | biostudies-arrayexpress