A multiplexed homology-directed DNA repair assay reveals the impact of over 1,000 BRCA1 missense substitution variants on protein function
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ABSTRACT:
PROVIDER: PRJNA478453 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR7451400.fastq.gz | Fastqsanger.gz | |||
| SRR7451410.fastq.gz | Fastqsanger.gz | |||
| SRR7451420.fastq.gz | Fastqsanger.gz | |||
| SRR7451391.fastq.gz | Fastqsanger.gz | |||
| SRR7451401.fastq.gz | Fastqsanger.gz |
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Project description:Delineating functionally normal variants from functionally abnormal variants in tumor suppressor proteins is critical for cancer surveillance, prognosis, and treatment options. BRCA1 is a protein that has many variants of uncertain significance which are not yet classified as functionally normal or abnormal. In vitro functional assays can be used to identify the functional impact of a variant when the variant has not yet been categorized through clinical observation. Here we employ a homology-directed repair (HDR) reporter assay to evaluate over 300 missense and nonsense BRCA1 variants between amino acid residues 1280 and 1576, which encompasses the coiled-coil and serine cluster domains. Functionally abnormal variants tended to cluster in residues known to interact with PALB2, which is critical for homology-directed repair. Multiplexed results were confirmed by singleton assay and by ClinVar database variant interpretations. Comparison of multiplexed results to designated benign or likely benign or pathogenic or likely pathogenic variants in the ClinVar database yielded 100% specificity and 100% sensitivity of the multiplexed assay. Clinicians can reference the results of this functional assay for help in guiding cancer treatment and surveillance options. These results are the first to evaluate this domain of BRCA1 using a multiplexed approach and indicate the importance of this domain in the DNA repair process.
2023-10-13 | GSE237142 | GEO
Project description:Here we describe a multiplex HDR reporter assay to concurrently measure the effects of hundreds of variants of BRCA1 for their role in DNA repair. Using this assay, we characterized the effects of 1,056 amino acid substitutions in the first 192 residues of BRCA1.
2018-06-29 | GSE116427 | GEO
Project description:In this study, we used multiplexed DNA repair assays of variants in the BRCA1 carboxy-terminus to functionally characterize 2271 variants for homology-directed repair function (HDR) and 1427 variants for cisplatin resistance (CR). We found a high level of consistent results in the two multiplexed functional assays with non-functional variants located within regions of the BRCA1 protein necessary for its tumor suppression activity.
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Project description:Single nucleotide variants are the most frequent type of sequence changes detected in the genome and these are frequently variants of uncertain significance (VUS). VUS are changes in DNA for which disease risk association is unknown. Thus, methods that classify the functional impact of a VUS can be used as evidence for variant interpretation. In the case of the breast and ovarian cancer specific tumor suppressor protein, BRCA1, pathogenic missense variants frequently score as loss of function in an assay for homology-directed repair (HDR) of DNA double-strand breaks. We previously published functional results using a multiplexed assay for 1056 amino acid substitutions residues 2-192 in the amino terminus of BRCA1. In this study, we have re-assessed the data from this multiplexed assay using an improved analysis pipeline. These new analysis methods yield functional scores for more variants in the first 192 amino acids of BRCA1, plus we report new results for BRCA1 amino acid residues 193-302. We now present the functional classification of 2172 BRCA1 variants in BRCA1 residues 2-302 using the multiplexed HDR assay. Comparison of the functional determinations of the missense variants with clinically known benign or pathogenic variants indicated 93% sensitivity and 100% specificity for this assay. The results from BRCA1 variants tested in this assay are a resource for clinical geneticists for evidence to evaluate VUS in BRCA1.
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Project description:Loss-of-function pathogenic variants in BRCA1 confer a predisposition to breast and ovarian cancer. Genetic testing for sequence changes in BRCA1 frequently reveals a missense variant for which the impact on cancer risk and on the molecular function of BRCA1 is unknown. Functional BRCA1 is required for the homology-directed repair (HDR) of double-strand DNA breaks, a critical activity for maintaining genome integrity and tumor suppression. Here, we describe a multiplex HDR reporter assay for concurrently measuring the effects of hundreds of variants of BRCA1 for their role in DNA repair. Using this assay, we characterized the effects of 1,056 amino acid substitutions in the first 192 residues of BRCA1. Benchmarking these results against variants with known effects on DNA repair function or on cancer predisposition, we demonstrate accurate discrimination of loss-of-function versus benign missense variants. We anticipate that this assay can be used to functionally characterize BRCA1 missense variants at scale, even before the variants are observed in results from genetic testing.
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Project description:Missense mutations account for nearly 50% of pathogenic mutations in human genetic diseases, most lack effective treatments. Gene therapies, CRISPR-based gene editing, and RNA therapies including transfer RNA (tRNA) modalities are common strategies for potential treatments of genetic diseases. However, reported tRNA therapies are for nonsense mutations, how tRNAs can be engineered to correct missense mutations have not been explored. Here, we describe missense correcting tRNAs (mc-tRNAs) as a potential therapeutic modality for correcting pathogenic missense mutations. Mc-tRNAs are engineered tRNAs that are charged with one amino acid and read codons of another amino acid in translation in human cells. We first developed a series of fluorescence protein (FP)-based reporters that indicate successful correction of missense mutations via restoration of fluorescence signals. We engineered mc-tRNAs that effectively corrected Serine and Arginine missense mutations in the reporters and confirmed the amino acid substitution by protein mass spectrometry and mc-tRNA expression by tRNA sequencing. We examined the transcriptome response to the expression of mc-tRNAs and found some mc-tRNAs induced minimum transcriptomic changes. Furthermore, we applied an Arg-tRNAGln(CUG) mc-tRNA to rescue the autolytic activity of a pathogenic CAPN3 Arg-to-Gln mutant involved in limb-girdle muscular dystrophy type 2A. These results establish a versatile pipeline for mc-tRNA engineering and demonstrate the potential of mc-tRNA as an alternative therapeutic platform for the treatment of genetic disorders.
2024-01-04 | GSE236623 | GEO
Project description:Missense mutations account for nearly 50% of pathogenic mutations in human genetic diseases, most lack effective treatments. Gene therapies, CRISPR-based gene editing, and RNA therapies including transfer RNA (tRNA) modalities are common strategies for potential treatments of genetic diseases. However, reported tRNA therapies are for nonsense mutations, how tRNAs can be engineered to correct missense mutations have not been explored. Here, we describe missense correcting tRNAs (mc-tRNAs) as a potential therapeutic modality for correcting pathogenic missense mutations. Mc-tRNAs are engineered tRNAs that are charged with one amino acid and read codons of another amino acid in translation in human cells. We first developed a series of fluorescence protein (FP)-based reporters that indicate successful correction of missense mutations via restoration of fluorescence signals. We engineered mc-tRNAs that effectively corrected Serine and Arginine missense mutations in the reporters and confirmed the amino acid substitution by protein mass spectrometry and mc-tRNA expression by tRNA sequencing. We examined the transcriptome response to the expression of mc-tRNAs and found some mc-tRNAs induced minimum transcriptomic changes. Furthermore, we applied an Arg-tRNAGln(CUG) mc-tRNA to rescue the autolytic activity of a pathogenic CAPN3 Arg-to-Gln mutant involved in limb-girdle muscular dystrophy type 2A. These results establish a versatile pipeline for mc-tRNA engineering and demonstrate the potential of mc-tRNA as an alternative therapeutic platform for the treatment of genetic disorders.
2024-01-04 | GSE236622 | GEO
Project description:Nuclear deubiquitinase BAP1 (BRCA1-Associated Protein 1) is a core component of multiprotein complexes that promote transcription by reversing the ubiquitination of histone 2A (H2A). BAP1 is a tumor suppressor gene whose germline loss-of-function variants predispose to cancer. To our knowledge, there are very rare examples of different germline variants in the same gene causing either a NDD or a tumor predisposition syndrome. Here, we report a series of 11 de novo germline heterozygous missense BAP1 variants associated with a rare syndromic neurodevelopmental disorder (NDD). Functional analysis showed that most of the variants cannot rescue the consequences of BAP1 inactivation, suggesting a loss-of-function mechanism. In T cells isolated from two affected children, H2A deubiquitination was impaired in matching peripheral blood mononuclear cells, histone H3 K27 acetylation ChIP-seq indicated that these BAP1 variants induced genome-wide chromatin state alterations, with enrichment for regulatory regions surrounding genes of the ubiquitin-proteasome system (UPS). Altogether, these results define a clinical syndrome caused by rare germline missense BAP1 variants that alter chromatin remodeling through abnormal histone ubiquitination and lead to transcriptional dysregulation of developmental genes.
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Project description:BRCA1 (breast cancer 1, early onset) mutations confer a high breast and ovarian cancer risk. Most of BRCA1 cancer-predisposing mutations originate truncated proteins, but missense mutations have also been detected in familial breast and ovarian cancer patients. These variants are rare and their role in cancer predisposition is often difficult to ascertain. Our purpose in the present work was to study the molecular mechanisms affected in human cells by two BRCA1 missense variants both located in the second BRCA1 BRCT domain, M1775R and A1789T. These variants were isolated from familial breast cancer patients and their role in the pathogenesis of breast cancer was also investigated by a study previously performed by our group in yeast cells. Here we present a microarray study to compare the expression profiles of HeLa cells transfected with these two variants and HeLa cells transfected with BRCA1 wild type. Data analysis was performed by evaluating three comparisons: M1775R versus wild-type (M1775RvsWT-contrast), A1789T versus wild-type (A1789TvsWT-contrast) and the mutated BRCT domain versus wild-type (MutvsWT-contrast), obtained by considering the two variants as a unique BRCT mutation. We found 173 differentially expressed genes in MutvsWT-contrast, 201 in M1775RvsWT-contrast and 313 in A1789TvsWT-contrast. Our results showed that the considered BRCA1 variants had an impact on cell processes often deregulated in cancerogenesis, such as cell cycle progression and DNA damage response and repair. Thus, our study further supports the putative role in the pathogenesis of cancer of the M1775R and A1789T BRCA1 variants from a molecular point of view.
2012-06-01 | E-MTAB-761 | biostudies-arrayexpress
Project description:Re-coding of UGA codons as selenocysteine (Sec) codons in selenoproteins depends on a selenocysteine insertion sequence (SECIS) in the 3’ UTR of mRNAs of eukaryotic selenoproteins. SECIS-binding protein 2 (SECISBP2) increases the efficiency of this process. Pathogenic mutations in SECISBP2 reduce selenoprotein expression and lead to phenotypes associated with the reduction of deiodinase activities and selenoprotein N expression in humans. Two functions have been ascribed to SECISBP2: binding of SECIS elements in selenoprotein mRNAs and facilitation of co-translational Sec insertion. To separately probe both functions, we established here two mouse models carrying two pathogenic missense mutations in Secisbp2 previously identified in patients. We found that the C696R substitution in the RNAbinding domain abrogates SECIS binding and does not support selenoprotein translation above the level of a complete Secisbp2 null mutation. The R543Q missense substitution located in the selenocysteine insertion domain resulted in residual activity and caused reduced selenoprotein translation, as demonstrated by ribosomal profiling to determine the impact on UGA re-coding in individual selenoproteins. We found, however, that the R543Q variant is thermally unstable in vitro and completely degraded in the mouse liver in vivo, while being partially functional in the brain. The moderate impairment of selenoprotein expression in neurons led to astrogliosis and transcriptional induction of genes associated with immune responses. We conclude that differential SECISBP2 protein stability in individual cell types may dictate clinical phenotypes to a much greater extent than molecular interactions involving a mutated amino acid in SECISBP2 .
2019-07-26 | GSE119681 | GEO