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Palovcak A, Yuan F, Verdun R, Luo L, Zhang Y. Fanconi anemia associated protein 20 (FAAP20) plays an essential role in homology-directed repair of DNA double-strand breaks. Commun Biol 2023; 6:873. [PMID: 37620397 PMCID: PMC10449828 DOI: 10.1038/s42003-023-05252-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 08/17/2023] [Indexed: 08/26/2023] Open
Abstract
FAAP20 is a Fanconi anemia (FA) protein that associates with the FA core complex to promote FANCD2/FANCI monoubiquitination and activate the damage response to interstrand crosslink damage. Here, we report that FAAP20 has a marked role in homologous recombination at a DNA double-strand break not associated with an ICL and separable from its binding partner FANCA. While FAAP20's role in homologous recombination is not dependent on FANCA, we found that FAAP20 stimulates FANCA's biochemical activity in vitro and participates in the single-strand annealing pathway of double-strand break repair in a FANCA-dependent manner. This indicates that FAAP20 has roles in several homology-directed repair pathways. Like other homology-directed repair factors, FAAP20 loss causes a reduction in nuclear RAD51 Irradiation-induced foci; and sensitizes cancer cells to ionizing radiation and PARP inhibition. In summary, FAAP20 participates in DNA double strand break repair by supporting homologous recombination in a non-redundant manner to FANCA, and single-strand annealing repair via FANCA-mediated strand annealing activity.
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Affiliation(s)
- Anna Palovcak
- Department of Biochemistry & Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Fenghua Yuan
- Department of Biochemistry & Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Ramiro Verdun
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Liang Luo
- Department of Biochemistry & Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Yanbin Zhang
- Department of Biochemistry & Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
- Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
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2
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Zhou Q, Chen X, He H, Peng S, Zhang Y, Zhang J, Cheng L, Liu S, Huang M, Xie R, Lin T, Huang J. WD repeat domain 5 promotes chemoresistance and Programmed Death-Ligand 1 expression in prostate cancer. Theranostics 2021; 11:4809-4824. [PMID: 33754029 PMCID: PMC7978315 DOI: 10.7150/thno.55814] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/12/2021] [Indexed: 12/20/2022] Open
Abstract
Purpose: Advanced prostate cancer (PCa) has limited treatment regimens and shows low response to chemotherapy and immunotherapy, leading to poor prognosis. Histone modification is a vital mechanism of gene expression and a promising therapy target. In this study, we characterized WD repeat domain 5 (WDR5), a regulator of histone modification, and explored its potential therapeutic value in PCa. Experimental Design: We characterized specific regulators of histone modification, based on TCGA data. The expression and clinical features of WDR5 were analyzed in two dependent cohorts. The functional role of WDR5 was further investigated with siRNA and OICR-9429, a small molecular antagonist of WDR5, in vitro and in vivo. The mechanism of WDR5 was explored by RNA-sequencing and chromatin immunoprecipitation (ChIP). Results: WDR5 was overexpressed in PCa and associated with advanced clinicopathological features, and predicted poor prognosis. Both inhibition of WDR5 by siRNA and OICR-9429 could reduce proliferation, and increase apoptosis and chemosensitivity to cisplatin in vitro and in vivo. Interestingly, targeting WDR5 by siRNA and OICR-9429 could block IFN-γ-induced PD-L1 expression in PCa cells. Mechanistically, we clarified that some cell cycle, anti-apoptosis, DNA repair and immune related genes, including AURKA, CCNB1, E2F1, PLK1, BIRC5, XRCC2 and PD-L1, were directly regulated by WDR5 and OICR-9429 in H3K4me3 and c-Myc dependent manner. Conclusions: These data revealed that targeting WDR5 suppressed proliferation, enhanced apoptosis, chemosensitivity to cisplatin and immunotherapy in PCa. Therefore, our findings provide insight into OICR-9429 is a multi-potency and promising therapy drug, which improves the antitumor effect of cisplatin or immunotherapy in PCa.
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Affiliation(s)
- Qianghua Zhou
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Xu Chen
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Haixia He
- State Key Laboratory of Oncology in South China & Collaborative Innovation Center of Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, 510060, China
- Department of Medical Oncology, Sun Yat-sen University Cancer Center, Guangzhou, 510060, China
| | - Shengmeng Peng
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Yangjie Zhang
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Jingtong Zhang
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Liang Cheng
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Sen Liu
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Ming Huang
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Ruihui Xie
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
| | - Tianxin Lin
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
- Department of Urology, The Affiliated Kashi Hospital, Sun Yat-sen University, Kashi, China
| | - Jian Huang
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou 510120, China
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3
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Abstract
The repair of DNA double-strand breaks occurs through a series of defined steps that are evolutionarily conserved and well-understood in most experimental organisms. However, it is becoming increasingly clear that repair does not occur in isolation from other DNA transactions. Transcription of DNA produces topological changes, RNA species, and RNA-dependent protein complexes that can dramatically influence the efficiency and outcomes of DNA double-strand break repair. The transcription-associated history of several double-strand break repair factors is reviewed here, with an emphasis on their roles in regulating R-loops and the emerging role of R-loops in coordination of repair events. Evidence for nucleolytic processing of R-loops is also discussed, as well as the molecular tools commonly used to measure RNA-DNA hybrids in cells.
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Affiliation(s)
- Tanya T Paull
- The Department of Molecular Biosciences and the Howard Hughes Medical Institute, The University of Texas at Austin, Austin, TX, USA
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4
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Mirza-Aghazadeh-Attari M, Darband SG, Kaviani M, Mihanfar A, Aghazadeh Attari J, Yousefi B, Majidinia M. DNA damage response and repair in colorectal cancer: Defects, regulation and therapeutic implications. DNA Repair (Amst) 2018; 69:34-52. [PMID: 30055507 DOI: 10.1016/j.dnarep.2018.07.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 07/15/2018] [Accepted: 07/15/2018] [Indexed: 12/11/2022]
Abstract
DNA damage response, a key factor involved in maintaining genome integrity and stability, consists of several kinase-dependent signaling pathways, which sense and transduce DNA damage signal. The severity of damage appears to determine DNA damage responses, which can include cell cycle arrest, damage repair and apoptosis. A number of recent studies have demonstrated that defection in signaling through this network is thought to be an underlying mechanism behind the development and progression of various types of human malignancies, including colorectal cancer. In this review, colorectal cancer and its molecular pathology as well as DNA damage response is briefly introduced. Finally, the involvement of key components of this network in the initiation/progression, prognosis, response to treatment and development of drug resistance is comprehensively discussed.
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Affiliation(s)
- Mohammad Mirza-Aghazadeh-Attari
- Aging Research Institute, Tabriz University of Medical Sciences, Tabriz, Iran; Student Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Saber Ghazizadeh Darband
- Danesh Pey Hadi Co., Health Technology Development Center, Urmia University of Medical Sciences, Urmia, Iran
| | - Mojtaba Kaviani
- School of Nutrition and Dietetics, Acadia University, Wolfville, Nova Scotia, Canada
| | - Ainaz Mihanfar
- Stem Cell and Regenerative Medicine Institute, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Bahman Yousefi
- Molecular Medicine Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Maryam Majidinia
- Solid Tumor Research Center, Urmia University of Medical Sciences, Urmia, Iran.
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5
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Hatchi E, Skourti-Stathaki K, Ventz S, Pinello L, Yen A, Kamieniarz-Gdula K, Dimitrov S, Pathania S, McKinney KM, Eaton ML, Kellis M, Hill SJ, Parmigiani G, Proudfoot NJ, Livingston DM. BRCA1 recruitment to transcriptional pause sites is required for R-loop-driven DNA damage repair. Mol Cell 2015; 57:636-647. [PMID: 25699710 PMCID: PMC4351672 DOI: 10.1016/j.molcel.2015.01.011] [Citation(s) in RCA: 311] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 11/21/2014] [Accepted: 01/05/2015] [Indexed: 11/07/2022]
Abstract
The mechanisms contributing to transcription-associated genomic instability are both complex and incompletely understood. Although R-loops are normal transcriptional intermediates, they are also associated with genomic instability. Here, we show that BRCA1 is recruited to R-loops that form normally over a subset of transcription termination regions. There it mediates the recruitment of a specific, physiological binding partner, senataxin (SETX). Disruption of this complex led to R-loop-driven DNA damage at those loci as reflected by adjacent γ-H2AX accumulation and ssDNA breaks within the untranscribed strand of relevant R-loop structures. Genome-wide analysis revealed widespread BRCA1 binding enrichment at R-loop-rich termination regions (TRs) of actively transcribed genes. Strikingly, within some of these genes in BRCA1 null breast tumors, there are specific insertion/deletion mutations located close to R-loop-mediated BRCA1 binding sites within TRs. Thus, BRCA1/SETX complexes support a DNA repair mechanism that addresses R-loop-based DNA damage at transcriptional pause sites. Endogenous BRCA1 and senataxin (SETX) interact in a BRCA1-driven process BRCA1/SETX complexes are recruited to R-loop-associated termination regions (TRs) BRCA1/SETX complexes suppress transcriptional DNA damage arising at nearby R-loops BRCA1 breast cancers reveal indel mutations near BRCA1 TR binding regions
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Affiliation(s)
- Elodie Hatchi
- Department of Genetics, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA.
| | | | - Steffen Ventz
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA; Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA
| | - Luca Pinello
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA; Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA
| | - Angela Yen
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Computer Science and Artificial Intelligence Laboratory (CSAIL), MIT, Cambridge, MA 02139, USA
| | | | - Stoil Dimitrov
- Department of Genetics, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA
| | - Shailja Pathania
- Department of Genetics, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA
| | - Kristine M McKinney
- Department of Genetics, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA
| | - Matthew L Eaton
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Computer Science and Artificial Intelligence Laboratory (CSAIL), MIT, Cambridge, MA 02139, USA
| | - Manolis Kellis
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Computer Science and Artificial Intelligence Laboratory (CSAIL), MIT, Cambridge, MA 02139, USA
| | - Sarah J Hill
- Department of Genetics, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA
| | - Giovanni Parmigiani
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA; Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA
| | | | - David M Livingston
- Department of Genetics, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA.
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6
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Aguilera A, Gaillard H. Transcription and recombination: when RNA meets DNA. Cold Spring Harb Perspect Biol 2014; 6:6/8/a016543. [PMID: 25085910 DOI: 10.1101/cshperspect.a016543] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A particularly relevant phenomenon in cell physiology and proliferation is the fact that spontaneous mitotic recombination is strongly enhanced by transcription. The most accepted view is that transcription increases the occurrence of double-strand breaks and/or single-stranded DNA gaps that are repaired by recombination. Most breaks would arise as a consequence of the impact that transcription has on replication fork progression, provoking its stalling and/or breakage. Here, we discuss the mechanisms responsible for the cross talk between transcription and recombination, with emphasis on (1) the transcription-replication conflicts as the main source of recombinogenic DNA breaks, and (2) the formation of cotranscriptional R-loops as a major cause of such breaks. The new emerging questions and perspectives are discussed on the basis of the interference between transcription and replication, as well as the way RNA influences genome dynamics.
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Affiliation(s)
- Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla, 41092 Seville, Spain
| | - Hélène Gaillard
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla, 41092 Seville, Spain
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7
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Gaillard H, Herrera-Moyano E, Aguilera A. Transcription-associated genome instability. Chem Rev 2013; 113:8638-61. [PMID: 23597121 DOI: 10.1021/cr400017y] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Hélène Gaillard
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla , Av. Américo Vespucio s/n, 41092 Seville, Spain
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8
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Lin YL, Pasero P. Interference between DNA replication and transcription as a cause of genomic instability. Curr Genomics 2012; 13:65-73. [PMID: 22942676 PMCID: PMC3269018 DOI: 10.2174/138920212799034767] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 10/03/2011] [Accepted: 10/06/2011] [Indexed: 11/22/2022] Open
Abstract
Replication and transcription are key aspects of DNA metabolism that take place on the same template and potentially interfere with each other. Conflicts between these two activities include head-on or co-directional collisions between DNA and RNA polymerases, which can lead to the formation of DNA breaks and chromosome rearrangements. To avoid these deleterious consequences and prevent genomic instability, cells have evolved multiple mechanisms preventing replication forks from colliding with the transcription machinery. Yet, recent reports indicate that interference between replication and transcription is not limited to physical interactions between polymerases and that other cotranscriptional processes can interfere with DNA replication. These include DNA-RNA hybrids that assemble behind elongating RNA polymerases, impede fork progression and promote homologous recombination. Here, we discuss recent evidence indicating that R-loops represent a major source of genomic instability in all organisms, from bacteria to human, and are potentially implicated in cancer development.
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Affiliation(s)
- Yea-Lih Lin
- Institute of Human Genetics, CNRS-UPR1142, Montpellier, France
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9
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Poveda AM, Le Clech M, Pasero P. Transcription and replication: breaking the rules of the road causes genomic instability. Transcription 2012; 1:99-102. [PMID: 21326900 DOI: 10.4161/trns.1.2.12665] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Revised: 06/13/2010] [Accepted: 06/14/2010] [Indexed: 11/19/2022] Open
Abstract
Replication and transcription machineries progress at high speed on the same DNA template, which inevitably causes traffic accidents. Problems are not only caused by frontal collisions between polymerases, but also by cotranscriptional R-loops. These RNA-DNA hybrids induce genomic instability by blocking fork progression and could be implicated in the development of cancer.
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10
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Yenerall P, Krupa B, Zhou L. Mechanisms of intron gain and loss in Drosophila. BMC Evol Biol 2011; 11:364. [PMID: 22182367 PMCID: PMC3296678 DOI: 10.1186/1471-2148-11-364] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 12/19/2011] [Indexed: 12/02/2022] Open
Abstract
Background It is widely accepted that orthologous genes have lost or gained introns throughout evolution. However, the specific mechanisms that generate these changes have proved elusive. Introns are known to affect nearly every level of gene expression. Therefore, understanding their mechanism of evolution after their initial fixation in eukaryotes is pertinent to understanding the means by which organisms develop greater regulation and complexity. Results To investigate possible mechanisms of intron gain and loss, we identified 189 intron gain and 297 intron loss events among 11 Drosophila species. We then investigated these events for signatures of previously proposed mechanisms of intron gain and loss. This work constitutes the first comprehensive study into the specific mechanisms that may generate intron gains and losses in Drosophila. We report evidence of intron gain via transposon insertion; the first intron loss that may have occurred via non-homologous end joining; intron gains via the repair of a double strand break; evidence of intron sliding; and evidence that internal or 5' introns may not frequently be deleted via the self-priming of reverse transcription during mRNA-mediated intron loss. Our data also suggest that the transcription process may promote or result in intron gain. Conclusion Our findings support the occurrence of intron gain via transposon insertion, repair of double strand breaks, as well as intron loss via non-homologous end joining. Furthermore, our data suggest that intron gain may be enabled by or due to transcription, and we shed further light on the exact mechanism of mRNA-mediated intron loss.
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Affiliation(s)
- Paul Yenerall
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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11
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Davis L, Maizels N. DNA nicks promote efficient and safe targeted gene correction. PLoS One 2011; 6:e23981. [PMID: 21912657 PMCID: PMC3164693 DOI: 10.1371/journal.pone.0023981] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 08/01/2011] [Indexed: 01/15/2023] Open
Abstract
Targeted gene correction employs a site-specific DNA lesion to promote homologous recombination that eliminates mutation in a disease gene of interest. The double-strand break typically used to initiate correction can also result in genomic instability if deleterious repair occurs rather than gene correction, possibly compromising the safety of targeted gene correction. Here we show that single-strand breaks (nicks) and double-strand breaks both promote efficient gene correction. However, breaks promote high levels of inadvertent but heritable genomic alterations both locally and elsewhere in the genome, while nicks are accompanied by essentially no collateral local mutagenesis, and thus provide a safer approach to gene correction. Defining efficacy as the ratio of gene correction to local deletion, nicks initiate gene correction with 70-fold greater efficacy than do double-strand breaks (29.0±6.0% and 0.42±0.03%, respectively). Thus nicks initiate efficient gene correction, with limited local mutagenesis. These results have clear therapeutic implications, and should inform future design of meganucleases for targeted gene correction.
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Affiliation(s)
- Luther Davis
- Department of Immunology, University of Washington School of Medicine, Seattle, Washington, United States of America
- Northwest Genome Engineering Consortium, Seattle, Washington, United States of America
| | - Nancy Maizels
- Department of Immunology, University of Washington School of Medicine, Seattle, Washington, United States of America
- Department of Biochemistry, University of Washington School of Medicine, Seattle, Washington, United States of America
- Northwest Genome Engineering Consortium, Seattle, Washington, United States of America
- * E-mail:
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12
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Transcription inhibition by DRB potentiates recombinational repair of UV lesions in mammalian cells. PLoS One 2011; 6:e19492. [PMID: 21573160 PMCID: PMC3088672 DOI: 10.1371/journal.pone.0019492] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 04/07/2011] [Indexed: 01/04/2023] Open
Abstract
Homologous recombination (HR) is intricately associated with replication, transcription and DNA repair in all organisms studied. However, the interplay between all these processes occurring simultaneously on the same DNA molecule is still poorly understood. Here, we study the interplay between transcription and HR during ultraviolet light (UV)-induced DNA damage in mammalian cells. Our results show that inhibition of transcription with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) increases the number of UV-induced DNA lesions (γH2AX, 53BP1 foci formation), which correlates with a decrease in the survival of wild type or nucleotide excision repair defective cells. Furthermore, we observe an increase in RAD51 foci formation, suggesting HR is triggered in response to an increase in UV-induced DSBs, while inhibiting transcription. Unexpectedly, we observe that DRB fails to sensitise HR defective cells to UV treatment. Thus, increased RAD51 foci formation correlates with increased cell death, suggesting the existence of a futile HR repair of UV-induced DSBs which is linked to transcription inhibition.
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13
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Savolainen L, Cassel T, Helleday T. The XPD subunit of TFIIH is required for transcription-associated but not DNA double-strand break-induced recombination in mammalian cells. Mutagenesis 2010; 25:623-9. [PMID: 20833695 DOI: 10.1093/mutage/geq054] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Mutations in the XPD gene can give rise to three phenotypically distinct disorders: xeroderma pigmentosum (XP), trichothiodystrophy (TTD) or combined XP and Cockayne syndrome (CS) (XP/CS). The role of Xeroderma Pigmentosum group D protein (XPD) in nucleotide excision repair explains the increased risk of skin cancer in XP patients but not all the clinical phenotypes found in XP/CS or TTD patients. Here, we describe that the XPD-defective UV5 cell line is impaired in transcription-associated recombination (TAR), which can be reverted by the introduction of the wild-type XPD gene expressed from a vector. UV5 cells are defective in TAR, despite having intact transcription and homologous recombination (HR) repair of DNA double-strand breaks (DSBs). Interestingly, we find reduced spontaneous HR in XPD-defective cells, suggesting that transcription underlies a portion of spontaneous HR events. We also report that transcription-coupled repair (TCR)-defective cells, mutated in the Cockayne syndrome B (CSB) protein, have a defect in TAR, but not in DSB-induced HR. However, the TAR defect may be associated with a general transcription defect in CSB-deficient cells. In conclusion, we show a novel role for the XPD protein in TAR, linking TAR with TCR.
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Affiliation(s)
- Linda Savolainen
- Department of Genetics, Microbiology and Toxicology, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
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14
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Helleday T. Homologous recombination in cancer development, treatment and development of drug resistance. Carcinogenesis 2010; 31:955-60. [PMID: 20351092 DOI: 10.1093/carcin/bgq064] [Citation(s) in RCA: 196] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although DNA double-strand breaks (DSBs) are substrates for homologous recombination (HR) repair, it is becoming apparent that DNA lesions produced at replication forks, for instance by many anticancer drugs, are more significant substrates for HR repair. Cells defective in HR are hypersensitive to a wide variety of anticancer drugs, including those that do not produce DSBs. Several cancers have mutations in or epigenetically silenced HR genes, which explain the genetic instability that drives cancer development. There are an increasing number of reports suggesting that mutation or epigenetic silencing of HR genes explains the sensitivity of cancers to current chemotherapy treatments. Furthermore, there are also many examples of re-expression of HR genes in tumours to explain drug resistance. Emerging data suggest that there are several different subpathways of HR, which can compensate for each other. Unravelling the overlapping pathways in HR showed that BRCA1- and BRCA2-defective cells rely on the PARP protein for survival. This synthetic lethal interaction is now being exploited for selective treatment of BRCA1- and BRCA2-defective cancers with PARP inhibitors. Here, I discuss the diversity of HR and how it impacts on cancer with a particular focus on how HR can be exploited in future anticancer strategies.
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Affiliation(s)
- Thomas Helleday
- Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford OX3 7DQ, UK.
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15
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Abstract
Is it possible to mutate DNA during transcription? A new study shows that UV-damaged DNA is deaminated during transcription, which is a probable mechanism underlying CC tandem mutations found in the p53 gene in skin cancers.
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Affiliation(s)
- Thomas Helleday
- Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford, OX3 7DQ, UK.
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Current World Literature. Curr Opin Allergy Clin Immunol 2009; 9:574-8. [DOI: 10.1097/aci.0b013e328333c13c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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The S-phase checkpoint is required to respond to R-loops accumulated in THO mutants. Mol Cell Biol 2009; 29:5203-13. [PMID: 19651896 DOI: 10.1128/mcb.00402-09] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cotranscriptional R-loops are formed in yeast mutants of the THO complex, which functions at the interface between transcription and mRNA export. Despite the relevance of R-loops in transcription-associated recombination, the mechanisms by which they trigger recombination are still elusive. In order to understand how R-loops compromise genome stability, we have analyzed the genetic interaction of THO with 26 genes involved in replication, S-phase checkpoint, DNA repair, and chromatin remodeling. We found a synthetic growth defect in double null mutants of THO and S-phase checkpoint factors, such as the replication factor C- and PCNA-like complexes. Under replicative stress, R-loop-forming THO null mutants require functional S-phase checkpoint functions but not double-strand-break repair functions for survival. Furthermore, R-loop-forming hpr1Delta mutants display replication fork progression impairment at actively transcribed chromosomal regions and trigger Rad53 phosphorylation. We conclude that R-loop-mediated DNA damage activates the S-phase checkpoint, which is required for the cell survival of THO mutants under replicative stress. In light of these results, we propose a model in which R-loop-mediated recombination is explained by template switching.
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