1
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Raices M, Balmir F, Silva N, Li W, Grundy MK, Hoffman DK, Altendorfer E, Camacho CJ, Bernstein KA, Colaiácovo MP, Yanowitz J. Genetic and physical interactions reveal overlapping and distinct contributions to meiotic double-strand break formation in C. elegans. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.23.581796. [PMID: 38463951 PMCID: PMC10925144 DOI: 10.1101/2024.02.23.581796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Double-strand breaks (DSBs) are the most deleterious lesions experienced by our genome. Yet, DSBs are intentionally induced during gamete formation to promote the exchange of genetic material between homologous chromosomes. While the conserved topoisomerase-like enzyme Spo11 catalyzes DSBs, additional regulatory proteins-referred to as "Spo11 accessory factors"- regulate the number, timing, and placement of DSBs during early meiotic prophase ensuring that SPO11 does not wreak havoc on the genome. Despite the importance of the accessory factors, they are poorly conserved at the sequence level suggesting that these factors may adopt unique functions in different species. In this work, we present a detailed analysis of the genetic and physical interactions between the DSB factors in the nematode Caenorhabditis elegans providing new insights into conserved and novel functions of these proteins. This work shows that HIM-5 is the determinant of X-chromosome-specific crossovers and that its retention in the nucleus is dependent on DSB-1, the sole accessory factor that interacts with SPO-11. We further provide evidence that HIM-5 coordinates the actions of the different accessory factors sub-groups, providing insights into how components on the DNA loops may interact with the chromosome axis.
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Affiliation(s)
| | - Fabiola Balmir
- Magee-Womens Research Institute, Pittsburgh, PA 15213 USA
| | - Nicola Silva
- Department of Biology, Masaryk University, Czech Republic
| | - Wei Li
- Magee-Womens Research Institute, Pittsburgh, PA 15213 USA
- Tsinghua U. Medical School, China
| | - McKenzie K. Grundy
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania
| | | | - Elisabeth Altendorfer
- Department of Genetics, Blavatnik Institute, Harvard Medical School, 77 Avenue Louis Pasteur, Room 334, Boston, MA 02115, USA
| | - Carlos Jaime Camacho
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213 USA
| | - Kara A. Bernstein
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania
- Department of Biochemistry and Biophysics, University of Pennsylvania, Penn Center for Genome Integrity, Philadelphia, Pennsylvania
| | - Monica P. Colaiácovo
- Department of Genetics, Blavatnik Institute, Harvard Medical School, 77 Avenue Louis Pasteur, Room 334, Boston, MA 02115, USA
| | - Judith Yanowitz
- Magee-Womens Research Institute, Pittsburgh, PA 15213 USA
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213 USA
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2
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Meng Q, Borris RP, Kim HM. Torenia sp. Extracts Contain Multiple Potent Antitumor Compounds with Nematocidal Activity, Triggering an Activated DNA Damage Checkpoint and Defective Meiotic Progression. Pharmaceuticals (Basel) 2024; 17:611. [PMID: 38794181 PMCID: PMC11124231 DOI: 10.3390/ph17050611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 05/03/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Previously, we analyzed 316 herbal extracts to evaluate their potential nematocidal properties in Caenorhabditis elegans. In this study, our attention was directed towards Torenia sp., resulting in reduced survival and heightened larval arrest/lethality, alongside a noticeable decrease in DAPI-stained bivalent structures and disrupted meiotic progression, thus disrupting developmental processes. Notably, Torenia sp. extracts activated a DNA damage checkpoint response via the ATM/ATR and CHK-1 pathways, hindering germline development. LC-MS analysis revealed 13 compounds in the Torenia sp. extracts, including flavonoids, terpenoids, tanshinones, an analog of resveratrol, iridoids, carotenoids, fatty acids, and alkaloids. Of these, 10 are known for their antitumor activity, suggesting the potential of Torenia species beyond traditional gardening, extending into pharmaceutical and therapeutic applications.
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Affiliation(s)
- Qinghao Meng
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Robert P. Borris
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Hyun-Min Kim
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan 215316, China
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3
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Arter M, Keeney S. Divergence and conservation of the meiotic recombination machinery. Nat Rev Genet 2024; 25:309-325. [PMID: 38036793 DOI: 10.1038/s41576-023-00669-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/03/2023] [Indexed: 12/02/2023]
Abstract
Sexually reproducing eukaryotes use recombination between homologous chromosomes to promote chromosome segregation during meiosis. Meiotic recombination is almost universally conserved in its broad strokes, but specific molecular details often differ considerably between taxa, and the proteins that constitute the recombination machinery show substantial sequence variability. The extent of this variation is becoming increasingly clear because of recent increases in genomic resources and advances in protein structure prediction. We discuss the tension between functional conservation and rapid evolutionary change with a focus on the proteins that are required for the formation and repair of meiotic DNA double-strand breaks. We highlight phylogenetic relationships on different time scales and propose that this remarkable evolutionary plasticity is a fundamental property of meiotic recombination that shapes our understanding of molecular mechanisms in reproductive biology.
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Affiliation(s)
- Meret Arter
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Scott Keeney
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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4
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Meng Q, Pathak N, Ren X, Borris RP, Kim HM. Exploring the Impact of Onobrychis cornuta and Veratrum lobelianum Extracts on C. elegans: Implications for MAPK Modulation, Germline Development, and Antitumor Properties. Nutrients 2023; 16:8. [PMID: 38201838 PMCID: PMC10780469 DOI: 10.3390/nu16010008] [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: 10/13/2023] [Revised: 12/12/2023] [Accepted: 12/14/2023] [Indexed: 01/12/2024] Open
Abstract
In an era of increasing interest in the potential health benefits of medicinal foods, the need to assess their safety and potential toxicity remains a critical concern. While these natural remedies have garnered substantial attention for their therapeutic potential, a comprehensive understanding of their effects on living organisms is essential. We examined 316 herbal extracts to determine their potential nematocidal attributes in Caenorhabditis elegans. Approximately 16% of these extracts exhibited the capacity to induce diminished survival rates and larval arrest, establishing a correlation between larval arrest and overall worm viability. Certain extracts led to an unexpected increase in male nematodes, accompanied by a discernible reduction in DAPI-stained bivalent structures and perturbed meiotic advancement, thereby disrupting the conventional developmental processes. Notably, Onobrychis cornuta and Veratrum lobelianum extracts activated a DNA damage checkpoint response via the ATM/ATR and CHK-1 pathways, thus hindering germline development. Our LC-MS analysis revealed jervine in V. lobelianum and nine antitumor compounds in O. cornuta. Interestingly, linoleic acid replicated phenotypes induced by O. cornuta exposure, including an increased level of pCHK-1 foci, apoptosis, and the MAPK pathway. Mutants in the MAPK pathway mitigated the decline in worm survival, underscoring its importance in promoting worm viability. This study reveals complex interactions between herbal extracts and C. elegans processes, shedding light on potential antitumor effects and mechanisms. The findings provide insights into the complex landscape of herbal medicine's impact on a model organism, offering implications for broader applications.
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Affiliation(s)
- Qinghao Meng
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China; (Q.M.); (N.P.); (R.P.B.)
| | - Nishit Pathak
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China; (Q.M.); (N.P.); (R.P.B.)
| | - Xiaojing Ren
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China; (Q.M.); (N.P.); (R.P.B.)
| | - Robert P. Borris
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China; (Q.M.); (N.P.); (R.P.B.)
| | - Hyun-Min Kim
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan 215316, China
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5
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Sun B, Sherrin M, Roy R. Unscheduled epigenetic modifications cause genome instability and sterility through aberrant R-loops following starvation. Nucleic Acids Res 2022; 51:84-98. [PMID: 36504323 PMCID: PMC9841415 DOI: 10.1093/nar/gkac1155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022] Open
Abstract
During starvation, organisms modify both gene expression and metabolism to adjust to the energy stress. We previously reported that Caenorhabditis elegans lacing AMP-activated protein kinase (AMPK) exhibit transgenerational reproductive defects associated with abnormally elevated trimethylated histone H3 at lysine 4 (H3K4me3) levels in the germ line following recovery from acute starvation. Here, we show that these H3K4me3 marks are significantly increased at promoters, driving aberrant transcription elongation resulting in the accumulation of R-loops in starved AMPK mutants. DNA-RNA immunoprecipitation followed by high-throughput sequencing (DRIP-seq) analysis demonstrated that a significant proportion of the genome was affected by R-loop formation. This was most pronounced in the promoter-transcription start site regions of genes, in which the chromatin was modified by H3K4me3. Like H3K4me3, the R-loops were also found to be heritable, likely contributing to the transgenerational reproductive defects typical of these mutants following starvation. Strikingly, AMPK mutant germ lines show considerably more RAD-51 (the RecA recombinase) foci at sites of R-loop formation, potentially sequestering them from their roles at meiotic breaks or at sites of induced DNA damage. Our study reveals a previously unforeseen role of AMPK in maintaining genome stability following starvation. The downstream effects of R-loops on DNA damage sensitivity and germline stem cell integrity may account for inappropriate epigenetic modification that occurs in numerous human disorders, including various cancers.
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Affiliation(s)
- Bing Sun
- To whom correspondence should be addressed.
| | - McLean Sherrin
- Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Richard Roy
- Correspondence may also be addressed to Richard Roy. Tel: +1 514 398 6437;
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6
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Trivedi S, Blazícková J, Silva N. PARG and BRCA1-BARD1 cooperative function regulates DNA repair pathway choice during gametogenesis. Nucleic Acids Res 2022; 50:12291-12308. [PMID: 36478097 PMCID: PMC9757042 DOI: 10.1093/nar/gkac1153] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/09/2022] [Accepted: 11/18/2022] [Indexed: 12/14/2022] Open
Abstract
Meiotic chromosome segregation relies on programmed DNA double-strand break induction. These are in turn repaired by homologous recombination, generating physical attachments between the parental chromosomes called crossovers. A subset of breaks yields recombinant outcomes, while crossover-independent mechanisms repair the majority of lesions. The balance between different repair pathways is crucial to ensure genome integrity. We show that Caenorhabditis elegans BRC-1/BRCA1-BRD-1/BARD1 and PARG-1/PARG form a complex in vivo, essential for accurate DNA repair in the germline. Simultaneous depletion of BRC-1 and PARG-1 causes synthetic lethality due to reduced crossover formation and impaired break repair, evidenced by hindered RPA-1 removal and presence of aberrant chromatin bodies in diakinesis nuclei, whose formation depends on spo-11 function. These factors undergo a similar yet independent loading in developing oocytes, consistent with operating in different pathways. Abrogation of KU- or Theta-mediated end joining elicits opposite effects in brc-1; parg-1 doubles, suggesting a profound impact in influencing DNA repair pathway choice by BRC-1-PARG-1. Importantly, lack of PARG-1 catalytic activity suppresses untimely accumulation of RAD-51 foci in brc-1 mutants but is only partially required for fertility. Our data show that BRC-1/BRD-1-PARG-1 joint function is essential for genome integrity in meiotic cells by regulating multiple DNA repair pathways.
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Affiliation(s)
- Shalini Trivedi
- Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, 62500 Brno, Czech Republic
| | - Jitka Blazícková
- Department of Biology, Faculty of Medicine, Masaryk University, Kamenice 5, 62500 Brno, Czech Republic
| | - Nicola Silva
- To whom correspondence should be addressed. Tel: +420 549 49 8033;
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7
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Silva N, Castellano-Pozo M, Matsuzaki K, Barroso C, Roman-Trufero M, Craig H, Brooks DR, Isaac RE, Boulton SJ, Martinez-Perez E. Proline-specific aminopeptidase P prevents replication-associated genome instability. PLoS Genet 2022; 18:e1010025. [PMID: 35081133 PMCID: PMC8820600 DOI: 10.1371/journal.pgen.1010025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 02/07/2022] [Accepted: 01/10/2022] [Indexed: 11/19/2022] Open
Abstract
Genotoxic stress during DNA replication constitutes a serious threat to genome integrity and causes human diseases. Defects at different steps of DNA metabolism are known to induce replication stress, but the contribution of other aspects of cellular metabolism is less understood. We show that aminopeptidase P (APP1), a metalloprotease involved in the catabolism of peptides containing proline residues near their N-terminus, prevents replication-associated genome instability. Functional analysis of C. elegans mutants lacking APP-1 demonstrates that germ cells display replication defects including reduced proliferation, cell cycle arrest, and accumulation of mitotic DSBs. Despite these defects, app-1 mutants are competent in repairing DSBs induced by gamma irradiation, as well as SPO-11-dependent DSBs that initiate meiotic recombination. Moreover, in the absence of SPO-11, spontaneous DSBs arising in app-1 mutants are repaired as inter-homologue crossover events during meiosis, confirming that APP-1 is not required for homologous recombination. Thus, APP-1 prevents replication stress without having an apparent role in DSB repair. Depletion of APP1 (XPNPEP1) also causes DSB accumulation in mitotically-proliferating human cells, suggesting that APP1’s role in genome stability is evolutionarily conserved. Our findings uncover an unexpected role for APP1 in genome stability, suggesting functional connections between aminopeptidase-mediated protein catabolism and DNA replication. The accurate duplication of DNA that occurs before cells divide is an essential aspect of the cell cycle that is also crucial for the correct development of multicellular organisms. Mutations that compromise the normal function of the DNA replication machinery can lead to the accumulation of replication-related DNA damage, a known cause of human disease and a common feature of cancer and precancerous cells. Therefore, identifying factors that prevent replication-related DNA damage is highly relevant for human health. In this manuscript, we identify aminopeptidase P, an enzyme involved in the breakdown of proteins containing the amino acid Proline at their N-terminus, as a novel factor that prevents replication-related DNA damage. Analysis of C. elegans nematodes lacking aminopeptidase P reveals that this protein is required for normal fertility and development, and that in its absence proliferating germ cells display DNA replication defects, including cell cycle arrest and accumulation of extensive DNA damage. We also show that removal of aminopeptidase P induces DNA damage in proliferating human cells, suggesting that its role in preventing replication defects is evolutionarily conserved. These findings uncover functional connections between aminopeptidase-mediated protein degradation and DNA replication.
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Affiliation(s)
- Nicola Silva
- Medical Research Council London Institute of Medical Sciences, London, United Kingdom
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | | | | | - Consuelo Barroso
- Medical Research Council London Institute of Medical Sciences, London, United Kingdom
| | - Monica Roman-Trufero
- Medical Research Council London Institute of Medical Sciences, London, United Kingdom
| | - Hannah Craig
- School of Biology, University of Leeds, Leeds, United Kingdom
| | - Darren R. Brooks
- School of Science, Engineering and Environment, University of Salford, Salford, United Kingdom
| | - R. Elwyn Isaac
- School of Biology, University of Leeds, Leeds, United Kingdom
| | | | - Enrique Martinez-Perez
- Medical Research Council London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, United Kingdom
- * E-mail:
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8
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Mechanism of mitotic recombination: insights from C. elegans. Curr Opin Genet Dev 2021; 71:10-18. [PMID: 34186335 PMCID: PMC8683258 DOI: 10.1016/j.gde.2021.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/18/2021] [Accepted: 06/07/2021] [Indexed: 11/23/2022]
Abstract
Homologous recombination (HR) plays a critical role in largely error-free repair of mitotic and meiotic DNA double-strand breaks (DSBs). DSBs are one of the most deleterious DNA lesions, which are repaired by non-homologous end joining (NHEJ), homologous recombination (HR) or, if compromised, micro-homology mediated end joining (MMEJ). If left unrepaired, DSBs can lead to cell death or if repaired incorrectly can result in chromosome rearrangements that drive cancer development. Here, we describe recent advances in the field of mitotic HR made using Caenorhabditis elegans roundworm, as a model system.
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9
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Lukaszewicz A, Lange J, Keeney S, Jasin M. De novo deletions and duplications at recombination hotspots in mouse germlines. Cell 2021; 184:5970-5984.e18. [PMID: 34793701 PMCID: PMC8616837 DOI: 10.1016/j.cell.2021.10.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 08/10/2021] [Accepted: 10/27/2021] [Indexed: 11/23/2022]
Abstract
Numerous DNA double-strand breaks (DSBs) arise during meiosis to initiate homologous recombination. These DSBs are usually repaired faithfully, but here, we uncover a distinct type of mutational event in which deletions form via joining of ends from two closely spaced DSBs (double cuts) within a single hotspot or at adjacent hotspots on the same or different chromatids. Deletions occur in normal meiosis but are much more frequent when DSB formation is dysregulated in the absence of the ATM kinase. Events between chromosome homologs point to multi-chromatid damage and aborted gap repair. Some deletions contain DNA from other hotspots, indicating that double cutting at distant sites creates substrates for insertional mutagenesis. End joining at double cuts can also yield tandem duplications or extrachromosomal circles. Our findings highlight the importance of DSB regulation and reveal a previously hidden potential for meiotic mutagenesis that is likely to affect human health and genome evolution.
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Affiliation(s)
- Agnieszka Lukaszewicz
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Julian Lange
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Scott Keeney
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Memorial Sloan Kettering Cancer Center, Howard Hughes Medical Institute, New York, NY 10065, USA.
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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10
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Harrell K, Day M, Smolikove S. Recruitment of MRE-11 to complex DNA damage is modulated by meiosis-specific chromosome organization. Mutat Res 2021; 822:111743. [PMID: 33975127 DOI: 10.1016/j.mrfmmm.2021.111743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/11/2021] [Accepted: 04/15/2021] [Indexed: 12/15/2022]
Abstract
DNA double-strand breaks (DSBs) are one of the most dangerous assaults on the genome, and yet their natural and programmed production are inherent to life. When DSBs arise close together they are particularly deleterious, and their repair may require an altered form of the DNA damage response. Our understanding of how clustered DSBs are repaired in the germline is unknown. Using laser microirradiation, we examine early events in the repair of clustered DSBs in germ cells within Caenorhabditis elegans. We use precise temporal resolution to show how the recruitment of MRE-11 to complex damage is regulated, and that clustered DNA damage can recruit proteins from various repair pathways. Abrogation of non-homologous end joining or COM-1 attenuates the recruitment of MRE-11 through distinct mechanisms. The synaptonemal complex plays both positive and negative regulatory roles in these mutant contexts. These findings indicate that MRE-11 is regulated by modifying its accessibility to chromosomes.
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Affiliation(s)
- Kailey Harrell
- Department of Biology, University of Iowa, Iowa City, IA, 52241, USA
| | - Madison Day
- Department of Biology, University of Iowa, Iowa City, IA, 52241, USA
| | - Sarit Smolikove
- Department of Biology, University of Iowa, Iowa City, IA, 52241, USA.
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11
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Dello Stritto MR, Bauer B, Barraud P, Jantsch V. DNA topoisomerase 3 is required for efficient germ cell quality control. J Cell Biol 2021; 220:211935. [PMID: 33798260 PMCID: PMC8025215 DOI: 10.1083/jcb.202012057] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 02/21/2021] [Accepted: 03/12/2021] [Indexed: 12/31/2022] Open
Abstract
An important quality control mechanism eliminates meiocytes that have experienced recombination failure during meiosis. The culling of defective oocytes in Caenorhabditis elegans meiosis resembles late oocyte elimination in female mammals. Here we show that topoisomerase 3 depletion generates DNA lesions in both germline mitotic and meiotic compartments that are less capable of triggering p53 (cep-1)–dependent apoptosis, despite the activation of DNA damage and apoptosis signaling. Elimination of nonhomologous, alternative end joining and single strand annealing repair factors (CKU-70, CKU-80, POLQ-1, and XPF-1) can alleviate the apoptosis block. Remarkably, the ability of single mutants in the other members of the Bloom helicase-topoisomerase-RMI1 complex to elicit apoptosis is not compromised, and depletion of Bloom helicase in topoisomerase 3 mutants restores an effective apoptotic response. Therefore, uncontrolled Bloom helicase activity seems to direct DNA repair toward normally not used repair pathways, and this counteracts efficient apoptosis. This implicates an as-yet undescribed requirement for topoisomerase 3 in mounting an effective apoptotic response to ensure germ cell quality control.
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Affiliation(s)
- Maria Rosaria Dello Stritto
- Department of Chromosome Biology, Max Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Bernd Bauer
- Department of Chromosome Biology, Max Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Pierre Barraud
- Expression Génétique Microbienne, UMR 8261, Centre Nationale de la Recherche Scientific, Université de Paris, Institut de Biologie Physico-Chimique, Paris, France
| | - Verena Jantsch
- Department of Chromosome Biology, Max Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
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12
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Lin M, Lv J, Zhao D, Liu S, Xu J, Wu Y, Wang F, Zhang J, Zheng B, Shen C, Guan X, Yu J, Huang X. MRNIP is essential for meiotic progression and spermatogenesis in mice. Biochem Biophys Res Commun 2021; 550:127-133. [PMID: 33689881 DOI: 10.1016/j.bbrc.2021.02.143] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 02/27/2021] [Indexed: 12/14/2022]
Abstract
Meiotic homologous recombination (HR) initiates with the programmed generation of DNA double-strand breaks (DSBs), which result in the exchange of genetic information and genome diversity. This process requires the tight cooperation of the MRE11-RAD50-NBS1 (MRN) complex to promote DSB formation and DNA end resection. However, the mechanism regulating MRN complex remains to be explored. In the present study, we report that MRN-interacting protein, MRNIP, is a novel factor for HR and is crucial for the expression of the MRN complex and loading of recombinases DMC1/RAD51. Knockout of Mrnip in mice led to aberrant synapsis, impaired HR, and male subfertility. In conclusion, MRNIP is a novel HR factor that probably promotes meiotic progression through the MRN complex.
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Affiliation(s)
- Meng Lin
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Jinxing Lv
- Suzhou Dushu Lake Hospital (Dushu Lake Hospital Affiliated to Soochow University), Suzhou, China
| | - Dan Zhao
- Fourth Affiliated Hospital of Jiangsu University, Zhenjiang, China
| | - Siyu Liu
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Jinfu Xu
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Yangyang Wu
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Fuxin Wang
- Center for Reproduction and Genetics, Suzhou Municipal Hospital, Suzhou, China
| | - Jun Zhang
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Bo Zheng
- Center for Reproduction and Genetics, Suzhou Municipal Hospital, Suzhou, China
| | - Cong Shen
- Center for Reproduction and Genetics, Suzhou Municipal Hospital, Suzhou, China.
| | - Xie Guan
- NHC Key Laboratory of Birth Defects and Reproductive Health (Chongqing Key Laboratory of Birth Defects and Reproductive Health, Chongqing Population and Family Planning Science and Technology Research Institute), Chongqing, China.
| | - Jun Yu
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong, China.
| | - Xiaoyan Huang
- State Key Laboratory of Reproductive Medicine, Department of Histology and Embryology, Nanjing Medical University, Nanjing, China.
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13
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Yadav VK, Claeys Bouuaert C. Mechanism and Control of Meiotic DNA Double-Strand Break Formation in S. cerevisiae. Front Cell Dev Biol 2021; 9:642737. [PMID: 33748134 PMCID: PMC7968521 DOI: 10.3389/fcell.2021.642737] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/01/2021] [Indexed: 12/17/2022] Open
Abstract
Developmentally programmed formation of DNA double-strand breaks (DSBs) by Spo11 initiates a recombination mechanism that promotes synapsis and the subsequent segregation of homologous chromosomes during meiosis. Although DSBs are induced to high levels in meiosis, their formation and repair are tightly regulated to minimize potentially dangerous consequences for genomic integrity. In S. cerevisiae, nine proteins participate with Spo11 in DSB formation, but their molecular functions have been challenging to define. Here, we describe our current view of the mechanism of meiotic DSB formation based on recent advances in the characterization of the structure and function of DSB proteins and discuss regulatory pathways in the light of recent models.
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Affiliation(s)
| | - Corentin Claeys Bouuaert
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-La-Neuve, Belgium
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14
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Gartner A, Engebrecht J. DNA repair, recombination, and damage signaling. Genetics 2021; 220:6522877. [PMID: 35137093 PMCID: PMC9097270 DOI: 10.1093/genetics/iyab178] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 10/10/2021] [Indexed: 01/09/2023] Open
Abstract
DNA must be accurately copied and propagated from one cell division to the next, and from one generation to the next. To ensure the faithful transmission of the genome, a plethora of distinct as well as overlapping DNA repair and recombination pathways have evolved. These pathways repair a large variety of lesions, including alterations to single nucleotides and DNA single and double-strand breaks, that are generated as a consequence of normal cellular function or by external DNA damaging agents. In addition to the proteins that mediate DNA repair, checkpoint pathways have also evolved to monitor the genome and coordinate the action of various repair pathways. Checkpoints facilitate repair by mediating a transient cell cycle arrest, or through initiation of cell suicide if DNA damage has overwhelmed repair capacity. In this chapter, we describe the attributes of Caenorhabditis elegans that facilitate analyses of DNA repair, recombination, and checkpoint signaling in the context of a whole animal. We review the current knowledge of C. elegans DNA repair, recombination, and DNA damage response pathways, and their role during development, growth, and in the germ line. We also discuss how the analysis of mutational signatures in C. elegans is helping to inform cancer mutational signatures in humans.
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Affiliation(s)
- Anton Gartner
- Department for Biological Sciences, IBS Center for Genomic Integrity, Ulsan National Institute of Science and Technology, Ulsan 689-798, Republic of Korea,Corresponding author: (A.G.); (J.E.)
| | - JoAnne Engebrecht
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA,Corresponding author: (A.G.); (J.E.)
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15
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Hatkevich T, Miller DE, Turcotte CA, Miller MC, Sekelsky J. A pathway for error-free non-homologous end joining of resected meiotic double-strand breaks. Nucleic Acids Res 2021; 49:879-890. [PMID: 33406239 PMCID: PMC7826270 DOI: 10.1093/nar/gkaa1205] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/22/2020] [Accepted: 11/25/2020] [Indexed: 12/31/2022] Open
Abstract
Programmed DNA double-strand breaks (DSBs) made during meiosis are repaired by recombination with the homologous chromosome to generate, at selected sites, reciprocal crossovers that are critical for the proper separation of homologs in the first meiotic division. Backup repair processes can compensate when the normal meiotic recombination processes are non-functional. We describe a novel backup repair mechanism that occurs when the homologous chromosome is not available in Drosophila melanogaster meiosis. In the presence of a previously described mutation (Mcm5A7) that disrupts chromosome pairing, DSB repair is initiated by homologous recombination but is completed by non-homologous end joining (NHEJ). Remarkably, this process yields precise repair products. Our results provide support for a recombination intermediate recently proposed in mouse meiosis, in which an oligonucleotide bound to the Spo11 protein that catalyzes DSB formation remains bound after resection. We propose that this oligonucleotide functions as a primer for fill-in synthesis to allow scarless repair by NHEJ. We argue that this is a conserved repair mechanism that is likely to be invoked to overcome occasional challenges in normal meiosis.
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Affiliation(s)
- Talia Hatkevich
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Danny E Miller
- Department of Pediatrics, Division of Medical Genetics, University of Washington, Seattle, Washington and Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Carolyn A Turcotte
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Margaret C Miller
- Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599, USA
| | - Jeff Sekelsky
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599, USA.,Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599, USA.,Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599, USA
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16
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Biswas L, Tyc K, Yakoubi WE, Morgan K, Xing J, Schindler K. Meiosis interrupted: the genetics of female infertility via meiotic failure. Reproduction 2021; 161:R13-R35. [PMID: 33170803 PMCID: PMC7855740 DOI: 10.1530/rep-20-0422] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 11/10/2020] [Indexed: 12/14/2022]
Abstract
Idiopathic or 'unexplained' infertility represents as many as 30% of infertility cases worldwide. Conception, implantation, and term delivery of developmentally healthy infants require chromosomally normal (euploid) eggs and sperm. The crux of euploid egg production is error-free meiosis. Pathologic genetic variants dysregulate meiotic processes that occur during prophase I, meiotic resumption, chromosome segregation, and in cell cycle regulation. This dysregulation can result in chromosomally abnormal (aneuploid) eggs. In turn, egg aneuploidy leads to a broad range of clinical infertility phenotypes, including primary ovarian insufficiency and early menopause, egg fertilization failure and embryonic developmental arrest, or recurrent pregnancy loss. Therefore, maternal genetic variants are emerging as infertility biomarkers, which could allow informed reproductive decision-making. Here, we select and deeply examine human genetic variants that likely cause dysregulation of critical meiotic processes in 14 female infertility-associated genes: SYCP3, SYCE1, TRIP13, PSMC3IP, DMC1, MCM8, MCM9, STAG3, PATL2, TUBB8, CEP120, AURKB, AURKC, andWEE2. We discuss the function of each gene in meiosis, explore genotype-phenotype relationships, and delineate the frequencies of infertility-associated variants.
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Affiliation(s)
- Leelabati Biswas
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
- Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Katarzyna Tyc
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Warif El Yakoubi
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Katie Morgan
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Jinchuan Xing
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
- Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Karen Schindler
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
- Human Genetics Institute of New Jersey, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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17
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McPherson MT, Holub AS, Husbands AY, Petreaca RC. Mutation Spectra of the MRN (MRE11, RAD50, NBS1/NBN) Break Sensor in Cancer Cells. Cancers (Basel) 2020; 12:cancers12123794. [PMID: 33339169 PMCID: PMC7765586 DOI: 10.3390/cancers12123794] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/04/2020] [Accepted: 12/14/2020] [Indexed: 12/12/2022] Open
Abstract
Simple Summary A DNA double strand break cuts a chromosome in two and is one of the most dangerous forms of DNA damage. Improper repair can lead to various chromosomal re-arrangements that have been detected in almost all cancer cells. A complex of three proteins (MRE11, RAD50, NBS1 or NBN) detects chromosome breaks and orchestrates repair processes. Mutations in these “break sensor” genes have been described in a multitude of cancers. Here, we provide a comprehensive analysis of reported mutations from data deposited on the Catalogue of Somatic Mutations in Cancer (COSMIC) archive. We also undertake an evolutionary analysis of these genes with the aim to understand whether these mutations preferentially accumulate in conserved residues. Interestingly, we find that mutations are overrepresented in evolutionarily conserved residues of RAD50 and NBS1/NBN but not MRE11. Abstract The MRN complex (MRE11, RAD50, NBS1/NBN) is a DNA double strand break sensor in eukaryotes. The complex directly participates in, or coordinates, several activities at the break such as DNA resection, activation of the DNA damage checkpoint, chromatin remodeling and recruitment of the repair machinery. Mutations in components of the MRN complex have been described in cancer cells for several decades. Using the Catalogue of Somatic Mutations in Cancer (COSMIC) database, we characterized all the reported MRN mutations. This analysis revealed several hotspot frameshift mutations in all three genes that introduce premature stop codons and truncate large regions of the C-termini. We also found through evolutionary analyses that COSMIC mutations are enriched in conserved residues of NBS1/NBN and RAD50 but not in MRE11. Given that all three genes are important to carcinogenesis, we propose these differential enrichment patterns may reflect a more severe pleiotropic role for MRE11.
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18
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Li Q, Hariri S, Engebrecht J. Meiotic Double-Strand Break Processing and Crossover Patterning Are Regulated in a Sex-Specific Manner by BRCA1-BARD1 in Caenorhabditis elegans. Genetics 2020; 216:359-379. [PMID: 32796008 PMCID: PMC7536853 DOI: 10.1534/genetics.120.303292] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 08/08/2020] [Indexed: 12/29/2022] Open
Abstract
Meiosis is regulated in a sex-specific manner to produce two distinct gametes, sperm and oocytes, for sexual reproduction. To determine how meiotic recombination is regulated in spermatogenesis, we analyzed the meiotic phenotypes of mutants in the tumor suppressor E3 ubiquitin ligase BRC-1-BRD-1 complex in Caenorhabditis elegans male meiosis. Unlike in mammals, this complex is not required for meiotic sex chromosome inactivation, the process whereby hemizygous sex chromosomes are transcriptionally silenced. Interestingly, brc-1 and brd-1 mutants show meiotic recombination phenotypes that are largely opposing to those previously reported for female meiosis. Fewer meiotic recombination intermediates marked by the recombinase RAD-51 were observed in brc-1 and brd-1 mutants, and the reduction in RAD-51 foci could be suppressed by mutation of nonhomologous-end-joining proteins. Analysis of GFP::RPA-1 revealed fewer foci in the brc-1brd-1 mutant and concentration of BRC-1-BRD-1 to sites of meiotic recombination was dependent on DNA end resection, suggesting that the complex regulates the processing of meiotic double-strand breaks to promote repair by homologous recombination. Further, BRC-1-BRD-1 is important to promote progeny viability when male meiosis is perturbed by mutations that block the pairing and synapsis of different chromosome pairs, although the complex is not required to stabilize the RAD-51 filament as in female meiosis under the same conditions. Analyses of crossover designation and formation revealed that BRC-1-BRD-1 inhibits supernumerary COs when meiosis is perturbed. Together, our findings suggest that BRC-1-BRD-1 regulates different aspects of meiotic recombination in male and female meiosis.
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Affiliation(s)
- Qianyan Li
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, California 95616
| | - Sara Hariri
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, California 95616
| | - JoAnne Engebrecht
- Department of Molecular and Cellular Biology, and Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California, Davis, California 95616
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19
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NBS1 is required for SPO11-linked DNA double-strand break repair in male meiosis. Cell Death Differ 2020; 27:2176-2190. [PMID: 31965061 PMCID: PMC7308329 DOI: 10.1038/s41418-020-0493-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 01/01/2020] [Accepted: 01/09/2020] [Indexed: 01/21/2023] Open
Abstract
DNA double-strand breaks (DSBs) pose a serious threat to genomic stability. Paradoxically, hundreds of programed DSBs are generated by SPO11 in meiotic prophase, which are exclusively repaired by homologous recombination (HR) to promote obligate crossover between homologous chromosomes. In somatic cells, MRE11-RAD50-NBS1 (MRN) complex-dependent DNA end resection is a prerequisite for HR repair, especially for DSBs that are covalently linked with proteins or chemicals. Interestingly, all meiotic DSBs are linked with SPO11 after being generated. Although MRN complex’s function in meiotic DSB repair has been established in lower organisms, the role of MRN complex in mammalian meiotic DSB repair is not clear. Here, we show that MRN complex is essential for repairing meiotic SPO11-linked DSBs in male mice. In male germ cells, conditional inactivation of NBS1, a key component of MRN complex, causes dramatic reduction of DNA end resection and defective HR repair in meiotic prophase. NBS1 loss severely disrupts chromosome synapsis, generates abnormal chromosome structures, and eventually leads to meiotic arrest and male infertility in mice. Unlike in somatic cells, the recruitment of NBS1 to SPO11-linked DSB sites is MDC1-independent but requires other phosphorylated proteins. Collectively, our study not only reveals the significance of MRN complex in repairing meiotic DSBs but also discovers a unique mechanism that recruits MRN complex to SPO11-linked DSB sites.
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20
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Bétermier M, Borde V, de Villartay JP. Coupling DNA Damage and Repair: an Essential Safeguard during Programmed DNA Double-Strand Breaks? Trends Cell Biol 2019; 30:87-96. [PMID: 31818700 DOI: 10.1016/j.tcb.2019.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/15/2019] [Accepted: 11/18/2019] [Indexed: 12/31/2022]
Abstract
DNA double-strand breaks (DSBs) are the most toxic DNA lesions given their oncogenic potential. Nevertheless, programmed DSBs (prDSBs) contribute to several biological processes. Formation of prDSBs is the 'price to pay' to achieve these essential biological functions. Generated by domesticated PiggyBac transposases, prDSBs have been integrated in the life cycle of ciliates. Created by Spo11 during meiotic recombination, they constitute a driving force of evolution and ensure balanced chromosome content for successful reproduction. Produced by the RAG1/2 recombinase, they are required for the development of the adaptive immune system in many species. The coevolution of processes that couple introduction of prDSBs to their accurate repair may constitute an effective safeguard against genomic instability.
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Affiliation(s)
- Mireille Bétermier
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France.
| | - Valérie Borde
- Institut Curie, CNRS UMR3244, Sorbonne Université, Paris, France.
| | - Jean-Pierre de Villartay
- Laboratory of Genome Dynamics in the Immune System, INSERM UMR1163, Université Paris Descartes Sorbonne Paris Cité, Institut Imagine, Paris, France.
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21
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Roelens B, Barroso C, Montoya A, Cutillas P, Zhang W, Woglar A, Girard C, Martinez-Perez E, Villeneuve AM. Spatial Regulation of Polo-Like Kinase Activity During Caenorhabditis elegans Meiosis by the Nucleoplasmic HAL-2/HAL-3 Complex. Genetics 2019; 213:79-96. [PMID: 31345995 PMCID: PMC6727811 DOI: 10.1534/genetics.119.302479] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 07/11/2019] [Indexed: 01/01/2023] Open
Abstract
Proper partitioning of homologous chromosomes during meiosis relies on the coordinated execution of multiple interconnected events: Homologs must locate, recognize, and align with their correct pairing partners. Further, homolog pairing must be coupled to assembly of the synaptonemal complex (SC), a meiosis-specific tripartite structure that maintains stable associations between the axes of aligned homologs and regulates formation of crossovers between their DNA molecules to create linkages that enable their segregation. Here, we identify HAL-3 (Homolog Alignment 3) as an important player in coordinating these key events during Caenorhabditis elegans meiosis. HAL-3, and the previously identified HAL-2, are interacting and interdependent components of a protein complex that localizes to the nucleoplasm of germ cells. hal-3 (or hal-2) mutants exhibit multiple meiotic prophase defects including failure to establish homolog pairing, inappropriate loading of SC subunits onto unpaired chromosome axes, and premature loss of synapsis checkpoint protein PCH-2. Further, loss of hal function results in misregulation of the subcellular localization and activity of Polo-like kinases (PLK-1 and PLK-2), which dynamically localize to different defined subnuclear sites during wild-type prophase progression to regulate distinct cellular events. Moreover, loss of PLK-2 activity partially restores tripartite SC structure in a hal mutant background, suggesting that the defect in pairwise SC assembly in hal mutants reflects inappropriate PLK activity. Together, our data support a model in which the nucleoplasmic HAL-2/HAL-3 protein complex constrains both localization and activity of meiotic Polo-like kinases, thereby preventing premature interaction with stage-inappropriate targets.
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Affiliation(s)
- Baptiste Roelens
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, California 94305
| | - Consuelo Barroso
- MRC London Institute of Medical Sciences, Imperial College London, W12 0NN, UK
| | - Alex Montoya
- MRC London Institute of Medical Sciences, Imperial College London, W12 0NN, UK
| | - Pedro Cutillas
- MRC London Institute of Medical Sciences, Imperial College London, W12 0NN, UK
| | - Weibin Zhang
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, California 94305
| | - Alexander Woglar
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, California 94305
| | - Chloe Girard
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, California 94305
| | | | - Anne M Villeneuve
- Departments of Developmental Biology and Genetics, Stanford University School of Medicine, California 94305
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22
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Oh J, Symington LS. Role of the Mre11 Complex in Preserving Genome Integrity. Genes (Basel) 2018; 9:E589. [PMID: 30501098 PMCID: PMC6315862 DOI: 10.3390/genes9120589] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 12/12/2022] Open
Abstract
DNA double-strand breaks (DSBs) are hazardous lesions that threaten genome integrity and cell survival. The DNA damage response (DDR) safeguards the genome by sensing DSBs, halting cell cycle progression and promoting repair through either non-homologous end joining (NHEJ) or homologous recombination (HR). The Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex is central to the DDR through its structural, enzymatic, and signaling roles. The complex tethers DNA ends, activates the Tel1/ATM kinase, resolves protein-bound or hairpin-capped DNA ends, and maintains telomere homeostasis. In addition to its role at DSBs, MRX/N associates with unperturbed replication forks, as well as stalled replication forks, to ensure complete DNA synthesis and to prevent chromosome rearrangements. Here, we summarize the significant progress made in characterizing the MRX/N complex and its various activities in chromosome metabolism.
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Affiliation(s)
- Julyun Oh
- Biological Sciences Program, Columbia University, New York, NY 10027, USA.
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
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23
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Meiotic Double-Strand Break Proteins Influence Repair Pathway Utilization. Genetics 2018; 210:843-856. [PMID: 30242011 DOI: 10.1534/genetics.118.301402] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 09/13/2018] [Indexed: 12/13/2022] Open
Abstract
Double-strand breaks (DSBs) are among the most deleterious lesions DNA can endure. Yet, DSBs are programmed at the onset of meiosis, and are required to facilitate appropriate reduction of ploidy in daughter cells. Repair of these breaks is tightly controlled to favor homologous recombination (HR)-the only repair pathway that can form crossovers. However, little is known about how the activities of alternative repair pathways are regulated at these stages. We discovered an unexpected synthetic interaction between the DSB machinery and strand-exchange proteins. Depleting the Caenorhabditis elegans DSB-promoting factors HIM-5 and DSB-2 suppresses the formation of chromosome fusions that arise in the absence of RAD-51 or other strand-exchange mediators. Our investigations reveal that nonhomologous and theta-mediated end joining (c-NHEJ and TMEJ, respectively) and single strand annealing (SSA) function redundantly to repair DSBs when HR is compromised, and that HIM-5 influences the utilization of TMEJ and SSA.
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Abstract
Sex in social amoebae (or dictyostelids) has a number of striking features. Dictyostelid zygotes do not proliferate but grow to a large size by feeding on other cells of the same species, each zygote ultimately forming a walled structure called a macrocyst. The diploid macrocyst nucleus undergoes meiosis, after which a single meiotic product survives to restart haploid vegetative growth. Meiotic recombination is generally initiated by the Spo11 enzyme, which introduces DNA double-strand breaks. Uniquely, as far as is known among sexual eukaryotes, dictyostelids lack a SPO11 gene. Despite this, recombination occurs at high frequencies during meiosis in dictyostelids, through unknown mechanisms. The molecular processes underlying these events, and the evolutionary drivers that brought them into being, may shed light on the genetic conflicts that occur within and between genomes, and how they can be resolved.
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