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Nepomuceno TC, Dos Santos APP, Fernandes VC, Elias ABR, Gomes TT, Suarez-Kurtz G, Iversen ES, Couch FJ, Monteiro ANA, Carvalho MA. Assessment of small in-frame indels and C-terminal nonsense variants of BRCA1 using a validated functional assay. Sci Rep 2022; 12:16203. [PMID: 36171434 PMCID: PMC9519549 DOI: 10.1038/s41598-022-20500-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 09/14/2022] [Indexed: 11/29/2022] Open
Abstract
BRCA1 (Breast Cancer 1, early onset) is linked to breast and ovarian cancer predisposition. Still, the risks conferred by a significant portion of BRCA1 variants identified in the population remains unknown. Most of these variants of uncertain significance are missense alterations. However, the functional implications of small in-frame deletions and/or insertions (indels) are also difficult to predict. Our group has previously evaluated the functional impact of 347 missense variants using an extensively validated transcriptional activity assay. Here we show a systematic assessment of 30 naturally occurring in-frame indels located at the C-terminal region of BRCA1. We identified positions sensitive and tolerant to alterations, expanding the knowledge of structural determinants of BRCA1 function. We further designed and assessed the impact of four single codon deletions in the tBRCT linker region and six nonsense variants at the C-terminus end of BRCA1. Amino acid substitutions, deletions or insertions in the disordered region do not significantly impact activity and are not likely to constitute pathogenic alleles. On the other hand, a sizeable fraction of in-frame indels at the BRCT domain significantly impact function. We then use a Bayesian integrative statistical model to derive the probability of pathogenicity for each variant. Our data highlights the importance of assessing the impact of small in-frame indels in BRCA1 to improve risk assessment and clinical decisions for carriers.
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Affiliation(s)
- Thales C Nepomuceno
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, 20230-130, Brazil.,Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL, 33612, USA
| | - Ana P P Dos Santos
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, 20230-130, Brazil
| | - Vanessa C Fernandes
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, 20230-130, Brazil
| | - Anna B R Elias
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, 20230-130, Brazil
| | - Thiago T Gomes
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, 20230-130, Brazil
| | - Guilherme Suarez-Kurtz
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, 20230-130, Brazil
| | - Edwin S Iversen
- Department of Statistical Science, Duke University, Durham, NC, 27708, USA
| | | | - Alvaro N A Monteiro
- Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL, 33612, USA.
| | - Marcelo A Carvalho
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, 20230-130, Brazil. .,Laboratório de Genética Molecular, Instituto Federal Do Rio de Janeiro, Rua Senador Furtado, Campus Rio de Janeiro121, Rio de Janeiro, RJ, 20270-021, Brazil.
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Abreu RBV, Gomes TT, Nepomuceno TC, Li X, Fuchshuber-Moraes M, De Gregoriis G, Suarez-Kurtz G, Monteiro ANA, Carvalho MA. Functional Restoration of BRCA1 Nonsense Mutations by Aminoglycoside-Induced Readthrough. Front Pharmacol 2022; 13:935995. [PMID: 35837282 PMCID: PMC9273842 DOI: 10.3389/fphar.2022.935995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 06/01/2022] [Indexed: 11/13/2022] Open
Abstract
BRCA1 is a major tumor suppressor that functions in the accurate repair of DNA double-strand breaks via homologous recombination (HR). Nonsense mutations in BRCA1 lead to inactive truncated protein products and are associated with high risk of breast and ovarian cancer. These mutations generate premature termination codons (PTCs). Different studies have shown that aminoglycosides can induce PTC suppression by promoting stop codon readthrough and restoring full-length (FL) protein expression. The use of these compounds has been studied in clinical trials for genetic diseases such as cystic fibrosis and Duchenne muscular dystrophy, with encouraging results. Here we show proof-of-concept data demonstrating that the aminoglycoside G418 can induce BRCA1 PTC readthrough and restore FL protein synthesis and function. We first demonstrate that G418 treatment restores BRCA1 FL protein synthesis in HCC1395, a human breast tumor cell line carrying the R1751X mutation. HCC1395 cells treated with G418 also recover HR DNA repair and restore cell cycle checkpoint activation. A set of naturally occurring BRCA1 nonsense variants encoding different PTCs was evaluated in a GFP C-terminal BRCA1 construct model and BRCA1 PTC readthrough levels vary depending on the stop codon context. Because PTC readthrough could generate FL protein carrying pathogenic missense mutations, variants representing the most probable acquired amino acid substitutions in consequence of readthrough were functionally assessed by a validated transcription activation assay. Overall, this is the first study that evaluates the readthrough of PTC variants with clinical relevance in the breast and ovarian cancer-predisposing gene BRCA1.
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Affiliation(s)
- Renata B. V. Abreu
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, Brazil
| | - Thiago T. Gomes
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, Brazil
| | - Thales C. Nepomuceno
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, Brazil
- Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, United States
| | - Xueli Li
- Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, United States
| | | | | | | | - Alvaro N. A. Monteiro
- Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, United States
| | - Marcelo A. Carvalho
- Divisão de Pesquisa Clínica, Instituto Nacional de Câncer, Rio de Janeiro, Brazil
- Instituto Federal do Rio de Janeiro—IFRJ, Rio de Janeiro, Brazil
- *Correspondence: Marcelo A. Carvalho,
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Fernandes VC, Golubeva VA, Di Pietro G, Shields C, Amankwah K, Nepomuceno TC, de Gregoriis G, Abreu RBV, Harro C, Gomes TT, Silva RF, Suarez-Kurtz G, Couch FJ, Iversen ES, Monteiro ANA, Carvalho MA. Impact of amino acid substitutions at secondary structures in the BRCT domains of the tumor suppressor BRCA1: Implications for clinical annotation. J Biol Chem 2019; 294:5980-5992. [PMID: 30765603 DOI: 10.1074/jbc.ra118.005274] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 02/06/2019] [Indexed: 01/07/2023] Open
Abstract
Genetic testing for BRCA1, a DNA repair protein, can identify carriers of pathogenic variants associated with a substantially increased risk for breast and ovarian cancers. However, an association with increased risk is unclear for a large fraction of BRCA1 variants present in the human population. Most of these variants of uncertain clinical significance lead to amino acid changes in the BRCA1 protein. Functional assays are valuable tools to assess the potential pathogenicity of these variants. Here, we systematically probed the effects of substitutions in the C terminus of BRCA1: the N- and C-terminal borders of its tandem BRCT domain, the BRCT-[N-C] linker region, and the α1 and α'1 helices in BRCT-[N] and -[C]. Using a validated transcriptional assay based on a fusion of the GAL4 DNA-binding domain to the BRCA1 C terminus (amino acids 1396-1863), we assessed the functional impact of 99 missense variants of BRCA1. We include the data obtained for these 99 missense variants in a joint analysis to generate the likelihood of pathogenicity for 347 missense variants in BRCA1 using VarCall, a Bayesian integrative statistical model. The results from this analysis increase our understanding of BRCA1 regions less tolerant to changes, identify functional borders of structural domains, and predict the likelihood of pathogenicity for 98% of all BRCA1 missense variants in this region recorded in the population. This knowledge will be critical for improving risk assessment and clinical treatment of carriers of BRCA1 variants.
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Affiliation(s)
- Vanessa C Fernandes
- From the Instituto Nacional de Câncer, Programa de Pesquisa Clínica, Rio de Janeiro, Brazil 20231-050
| | - Volha A Golubeva
- the Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612
| | - Giuliano Di Pietro
- the Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612; the Universidade Federal de Sergipe, Campus São Cristóvão, Brazil 49100-000
| | - Cara Shields
- the Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612
| | - Kwabena Amankwah
- the Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612
| | - Thales C Nepomuceno
- From the Instituto Nacional de Câncer, Programa de Pesquisa Clínica, Rio de Janeiro, Brazil 20231-050; the Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612
| | - Giuliana de Gregoriis
- From the Instituto Nacional de Câncer, Programa de Pesquisa Clínica, Rio de Janeiro, Brazil 20231-050
| | - Renata B V Abreu
- From the Instituto Nacional de Câncer, Programa de Pesquisa Clínica, Rio de Janeiro, Brazil 20231-050
| | - Carly Harro
- the Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612; the Department of Cell Biology, Microbiology, College of Arts and Sciences, University of South Florida Cancer Biology Ph.D. Program, Tampa, Florida 33612
| | - Thiago T Gomes
- the Instituto Federal do Rio de Janeiro, Rio de Janeiro 20270-021, Brazil
| | - Ricceli F Silva
- the Instituto Federal do Rio de Janeiro, Rio de Janeiro 20270-021, Brazil
| | - Guilherme Suarez-Kurtz
- From the Instituto Nacional de Câncer, Programa de Pesquisa Clínica, Rio de Janeiro, Brazil 20231-050
| | - Fergus J Couch
- the Department of Laboratory Medicine, Mayo Clinic, Rochester, Minnesota 55905
| | - Edwin S Iversen
- the Department of Statistics, Duke University, Durham, North Carolina 27710
| | - Alvaro N A Monteiro
- the Cancer Epidemiology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612.
| | - Marcelo A Carvalho
- From the Instituto Nacional de Câncer, Programa de Pesquisa Clínica, Rio de Janeiro, Brazil 20231-050.
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Nepomuceno TC, Fernandes VC, Gomes TT, Carvalho RS, Suarez-Kurtz G, Monteiro AN, Carvalho MA. BRCA1 recruitment to damaged DNA sites is dependent on CDK9. Cell Cycle 2017; 16:665-672. [PMID: 28278048 DOI: 10.1080/15384101.2017.1295177] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Double strand break lesions, the most toxic type of DNA damage, are repaired primarily through 2 distinct pathways: homology-directed recombination (HR) and non-homologous end-joining (NHEJ). BRCA1 and 53BP1, 2 proteins containing the BRCT modular domain, play an important role in DNA damage response (DDR) by orchestrating the decision between HR and NHEJ, but the precise mechanisms regarding both pathways are not entirely understood. Previously, our group identified a putative interaction between BRCA1 and BARD1 (BRCA1-associated RING domain 1) and the cyclin-dependent kinase (CDK9). CDK9 is a component of the positive transcription elongation complex and has been implicated in genome integrity maintenance associated with the replication stress response. Here we show that CDK9 interacts with endogenous BRCA1 and BARD1 mediated by their RING finger and BRCT domains, and describe CDK9 ionizing radiation-induced foci (IRIF) formation and its co-localization with BRCA1 in DNA damage sites. Cells lacking CDK9 are characterized by an altered γ-H2AX foci dynamics after DNA damage, a reduced efficiency in HR but not in NHEJ repair, failure to form BRCA1 and RAD51 IRIF and increased sensitivity to genotoxic agents. These data indicate that CDK9 is a player in the DDR and is consistent with its participation in HR pathway by modulating BRCA1 response.
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Affiliation(s)
- Thales C Nepomuceno
- a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil
| | - Vanessa C Fernandes
- a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil
| | - Thiago T Gomes
- b Instituto Federal do Rio de Janeiro - IFRJ , Rio de Janeiro , Brazil
| | - Renato S Carvalho
- c Faculdade de Farmácia - Universidade Federal do Rio de Janeiro , Rio de Janeiro , RJ , Brazil
| | | | - Alvaro N Monteiro
- d Cancer Epidemiology Program , H. Lee Moffitt Cancer Center & Research Institute , Tampa , FL , USA
| | - Marcelo A Carvalho
- a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil.,b Instituto Federal do Rio de Janeiro - IFRJ , Rio de Janeiro , Brazil
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Abstract
Sixteen strains of Vibrio furnissii recovered from 16 Brazilian patients with diarrhea were screened for virulence-associated factors. All strains were non-invasive, non-fimbriated, and did not produce either enterotoxins or cholera-like toxin. In contrast, most were hemolytic on blood agar and their broth-culture supernatants damaged HeLa cell monolayers. These cytolysins, as accepted for other enteropathogenic members of the family Vibrionaceae, might be determinants of pathogenicity in V. furnissii-mediated enteritis.
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Affiliation(s)
- V Magalhães
- Laboratório Keizo Asami, Universidade Federal de Pernambuco, Cidade Universitária, Recife, Brasil
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