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Leung CWB, Wall J, Esashi F. From rest to repair: Safeguarding genomic integrity in quiescent cells. DNA Repair (Amst) 2024; 142:103752. [PMID: 39167890 DOI: 10.1016/j.dnarep.2024.103752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 08/12/2024] [Accepted: 08/12/2024] [Indexed: 08/23/2024]
Abstract
Quiescence is an important non-pathological state in which cells pause cell cycle progression temporarily, sometimes for decades, until they receive appropriate proliferative stimuli. Quiescent cells make up a significant proportion of the body, and maintaining genomic integrity during quiescence is crucial for tissue structure and function. While cells in quiescence are spared from DNA damage associated with DNA replication or mitosis, they are still exposed to various sources of endogenous DNA damage, including those induced by normal transcription and metabolism. As such, it is vital that cells retain their capacity to effectively repair lesions that may occur and return to the cell cycle without losing their cellular properties. Notably, while DNA repair pathways are often found to be downregulated in quiescent cells, emerging evidence suggests the presence of active or differentially regulated repair mechanisms. This review aims to provide a current understanding of DNA repair processes during quiescence in mammalian systems and sheds light on the potential pathological consequences of inefficient or inaccurate repair in quiescent cells.
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Affiliation(s)
| | - Jacob Wall
- Sir William Dunn School of Pathology, South Parks Road, Oxford, UK
| | - Fumiko Esashi
- Sir William Dunn School of Pathology, South Parks Road, Oxford, UK.
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2
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Estrem B, Davis R, Wang J. End resection and telomere healing of DNA double-strand breaks during nematode programmed DNA elimination. Nucleic Acids Res 2024; 52:8913-8929. [PMID: 38953168 PMCID: PMC11347171 DOI: 10.1093/nar/gkae579] [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] [Received: 03/15/2024] [Revised: 05/24/2024] [Accepted: 06/24/2024] [Indexed: 07/03/2024] Open
Abstract
Most DNA double-strand breaks (DSBs) are harmful to genome integrity. However, some forms of DSBs are essential to biological processes, such as meiotic recombination and V(D)J recombination. DSBs are also required for programmed DNA elimination (PDE) in ciliates and nematodes. In nematodes, the DSBs are healed with telomere addition. While telomere addition sites have been well characterized, little is known regarding the DSBs that fragment nematode chromosomes. Here, we used embryos from the human and pig parasitic nematode Ascaris to characterize the DSBs. Using END-seq, we demonstrate that DSBs are introduced before mitosis, followed by extensive end resection. The resection profile is unique for each break site, and the resection generates 3'-overhangs before the addition of neotelomeres. Interestingly, telomere healing occurs much more frequently on retained DSB ends than on eliminated ends. This biased repair of the DSB ends may be due to the sequestration of the eliminated DNA into micronuclei, preventing neotelomere formation at their ends. Additional DNA breaks occur within the eliminated DNA in both Ascaris and Parascaris, ensuring chromosomal breakage and providing a fail-safe mechanism for PDE. Overall, our data indicate that telomere healing of DSBs is specific to the break sites responsible for nematode PDE.
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Affiliation(s)
- Brandon Estrem
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Richard E Davis
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jianbin Wang
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA
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3
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Kim S, Yamada S, Maekawa K, Keeney S. Optimized methods for mapping DNA double-strand-break ends and resection tracts and application to meiotic recombination in mouse spermatocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.10.606181. [PMID: 39149289 PMCID: PMC11326271 DOI: 10.1101/2024.08.10.606181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
DNA double-strand breaks (DSBs) made by SPO11 protein initiate homologous recombination during meiosis. Subsequent to DNA strand breakage, endo- and exo-nucleases process the DNA ends to resect the strands whose 5´ termini are at the DSB, generating long 3´-terminal single-stranded tails that serve as substrates for strand exchange proteins. DSB resection is essential for meiotic recombination, but a detailed understanding of its molecular mechanism is currently lacking. Genomic approaches to mapping DSBs and resection endpoints, e.g., S1-sequencing (S1-seq) and similar methods, play a critical role in studies of meiotic DSB processing. In these methods, nuclease S1 or other enzymes that specifically degrade ssDNA are used to trim resected DSBs, allowing capture and sequencing of the ends of resection tracts. Here, we present optimization of S1-seq that improves its signal:noise ratio and allows its application to analysis of spermatocyte meiosis in adult mice. Furthermore, quantitative features of meiotic resection are evaluated for reproducibility, and we suggest approaches for analysis and interpretation of S1-seq data. We also compare S1-seq to variants that use exonuclease T and/or exonuclease VII from Escherichia coli instead of nuclease S1. Detailed step-by-step protocols and suggestions for troubleshooting are provided.
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Affiliation(s)
- Soonjoung Kim
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
- Department of Microbiology and Immunology, Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Shintaro Yamada
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
- The HAKUBI Center for Advanced Research, and Department of Aging Science and Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kaku Maekawa
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases and the Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Scott Keeney
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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4
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Duardo RC, Marinello J, Russo M, Morelli S, Pepe S, Guerra F, Gómez-González B, Aguilera A, Capranico G. Human DNA topoisomerase I poisoning causes R loop-mediated genome instability attenuated by transcription factor IIS. SCIENCE ADVANCES 2024; 10:eadm8196. [PMID: 38787953 PMCID: PMC11122683 DOI: 10.1126/sciadv.adm8196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 04/18/2024] [Indexed: 05/26/2024]
Abstract
DNA topoisomerase I can contribute to cancer genome instability. During catalytic activity, topoisomerase I forms a transient intermediate, topoisomerase I-DNA cleavage complex (Top1cc) to allow strand rotation and duplex relaxation, which can lead to elevated levels of DNA-RNA hybrids and micronuclei. To comprehend the underlying mechanisms, we have integrated genomic data of Top1cc-triggered hybrids and DNA double-strand breaks (DSBs) shortly after Top1cc induction, revealing that Top1ccs increase hybrid levels with different mechanisms. DSBs are at highly transcribed genes in early replicating initiation zones and overlap with hybrids downstream of accumulated RNA polymerase II (RNAPII) at gene 5'-ends. A transcription factor IIS mutant impairing transcription elongation further increased RNAPII accumulation likely due to backtracking. Moreover, Top1ccs can trigger micronuclei when occurring during late G1 or early/mid S, but not during late S. As micronuclei and transcription-replication conflicts are attenuated by transcription factor IIS, our results support a role of RNAPII arrest in Top1cc-induced transcription-replication conflicts leading to DSBs and micronuclei.
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Affiliation(s)
- Renée C. Duardo
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum–University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Jessica Marinello
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum–University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Marco Russo
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum–University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Sara Morelli
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum–University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Simona Pepe
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum–University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Federico Guerra
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum–University of Bologna, via Selmi 3, 40126, Bologna, Italy
| | - Belén Gómez-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa—CABIMER, Universidad de Sevilla–CSIC, Calle Américo Vespucio 24, 41092 Seville, Spain
- Departamento de Genetica, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa—CABIMER, Universidad de Sevilla–CSIC, Calle Américo Vespucio 24, 41092 Seville, Spain
- Departamento de Genetica, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain
| | - Giovanni Capranico
- Department of Pharmacy and Biotechnology, Alma Mater Studiorum–University of Bologna, via Selmi 3, 40126, Bologna, Italy
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Cathcart B, Cheedipudi SM, Rouhi L, Zhao Z, Gurha P, Marian AJ. DNA double-stranded breaks, a hallmark of aging, defined at the nucleotide resolution, are increased and associated with transcription in the cardiac myocytes in LMNA-cardiomyopathy. Cardiovasc Res 2024:cvae063. [PMID: 38577741 DOI: 10.1093/cvr/cvae063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 03/19/2024] [Accepted: 03/20/2024] [Indexed: 04/06/2024] Open
Abstract
AIMS An intrinsic feature of gene transcription is the formation of DNA superhelices near the transcription bubble, which are resolved upon induction of transient double-stranded breaks (DSBs) by topoisomerases. Unrepaired DSBs are pathogenic as they lead to cell cycle arrest, senescence, inflammation, and organ dysfunction. We posit that DSBs would be more prevalent at the genomic sites that are associated with gene expression. The objectives were to identify and characterize genome-wide DSBs at the nucleotide resolution and determine the association of DSBs with transcription in cardiac myocytes. METHODS AND RESULTS We identified the genome-wide DSBs in ∼1 million cardiac myocytes per heart in three wild-type and three myocyte-specific LMNA-deficient (Myh6-Cre:LmnaF/F) mice by END-Sequencing. The prevalence of DSBs was 0.8% and 2.2% in the wild-type and Myh6-Cre:LmnaF/F myocytes, respectively. The END-Seq signals were enriched for 8 and 6764 DSBs in the wild-type and Myh6-Cre:LmnaF/F myocytes, respectively (q < 0.05). The DSBs were preferentially localized to the gene regions, transcription initiation sites, cardiac transcription factor motifs, and the G quadruplex forming structures. Because LMNA regulates transcription through the lamin-associated domains (LADs), we defined the LADs in cardiac myocytes by a Cleavage Under Targets & Release Using Nuclease (CUT&RUN) assay (N = 5). On average there were 818 LADs per myocyte. Constitutive LADs (cLADs), defined as LADs that were shared by at least three genomes (N = 2572), comprised about a third of the mouse cardiac myocyte genomes. Transcript levels of the protein-coding genes located at the cLADs (N = 3975) were ∼16-fold lower than those at the non-LAD regions (N = ∼17 778). The prevalence of DSBs was higher in the non-LAD as compared to the cLAD regions. Likewise, DSBs were more common in the loss-of-LAD regions, defined as the genomic regions in the Myh6-Cre:LmnaF/F that were juxtaposed to the LAD regions in the wild-type myocytes. CONCLUSION To our knowledge, this is the first identification of the DSBs, at the nucleotide resolution in the cardiovascular system. The prevalence of DSBs was higher in the genomic regions associated with transcription. Because transcription is pervasive, DSBs are expected to be common and pathogenic in various states and aging.
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Affiliation(s)
- Benjamin Cathcart
- Center for Cardiovascular Genetics, Institute of Molecular Medicine, The University of Texas Health Science Center, 6770 Bertner Street, Suite C900A, Houston, TX 77030, USA
| | - Sirisha M Cheedipudi
- Center for Cardiovascular Genetics, Institute of Molecular Medicine, The University of Texas Health Science Center, 6770 Bertner Street, Suite C900A, Houston, TX 77030, USA
| | - Leila Rouhi
- Center for Cardiovascular Genetics, Institute of Molecular Medicine, The University of Texas Health Science Center, 6770 Bertner Street, Suite C900A, Houston, TX 77030, USA
| | - Zhongming Zhao
- Center for Cardiovascular Genetics, Institute of Molecular Medicine, The University of Texas Health Science Center, 6770 Bertner Street, Suite C900A, Houston, TX 77030, USA
- Center for Precision Health, School of Biomedical Informatics and School of Public Health, UTHealth, Houston, TX 77030, USA
| | - Priyatansh Gurha
- Center for Cardiovascular Genetics, Institute of Molecular Medicine, The University of Texas Health Science Center, 6770 Bertner Street, Suite C900A, Houston, TX 77030, USA
| | - Ali J Marian
- Center for Cardiovascular Genetics, Institute of Molecular Medicine, The University of Texas Health Science Center, 6770 Bertner Street, Suite C900A, Houston, TX 77030, USA
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6
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Estrem B, Davis RE, Wang J. End resection and telomere healing of DNA double-strand breaks during nematode programmed DNA elimination. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.15.585292. [PMID: 38559121 PMCID: PMC10980081 DOI: 10.1101/2024.03.15.585292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Most DNA double-strand breaks (DSBs) are harmful to genome integrity. However, some forms of DSBs are essential to biological processes, such as meiotic recombination and V(D)J recombination. DSBs are also required for programmed DNA elimination (PDE) in ciliates and nematodes. In nematodes, the DSBs are healed with telomere addition. While telomere addition sites have been well-characterized, little is known regarding the DSBs that fragment nematode chromosomes. Here, we used embryos from the nematode Ascaris to study the timing of PDE breaks and examine the DSBs and their end processing. Using END-seq, we characterize the DSB ends and demonstrate that DNA breaks are introduced before mitosis, followed by extensive end resection. The resection profile is unique for each break site, and the resection generates 3' overhangs before the addition of telomeres. Interestingly, telomere healing occurs much more frequently on retained DSB ends than on eliminated ends. This biased repair of the DSB ends in Ascaris may be due to the sequestration of the eliminated DNA into micronuclei, preventing their ends from telomere healing. Additional DNA breaks occur within the eliminated DNA in both Ascaris and Parascaris, ensuring chromosomal breakage and providing a fail-safe mechanism for nematode PDE.
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Affiliation(s)
- Brandon Estrem
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Richard E. Davis
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Jianbin Wang
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN, 37996, USA
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7
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Xu S, Wei J, Sun S, Zhang J, Chan TF, Li Y. SSBlazer: a genome-wide nucleotide-resolution model for predicting single-strand break sites. Genome Biol 2024; 25:46. [PMID: 38347618 PMCID: PMC10863285 DOI: 10.1186/s13059-024-03179-w] [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: 08/31/2022] [Accepted: 01/24/2024] [Indexed: 02/15/2024] Open
Abstract
Single-strand breaks are the major DNA damage in the genome and serve a crucial role in various biological processes. To reveal the significance of single-strand breaks, multiple sequencing-based single-strand break detection methods have been developed, which are costly and unfeasible for large-scale analysis. Hence, we propose SSBlazer, an explainable and scalable deep learning framework for single-strand break site prediction at the nucleotide level. SSBlazer is a lightweight model with robust generalization capabilities across various species and is capable of numerous unexplored SSB-related applications.
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Affiliation(s)
- Sheng Xu
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, 100871, Hong Kong SAR, China
- Research Institute of Intelligent Complex Systems, Fudan University, 220 Handan Rd, Shanghai, 200437, China
- Shanghai AI Lab, 422 Jingan Rd, 200041, Shanghai, China
| | - Junkang Wei
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, 100871, Hong Kong SAR, China.
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, USA.
| | - Siqi Sun
- Research Institute of Intelligent Complex Systems, Fudan University, 220 Handan Rd, Shanghai, 200437, China
- Shanghai AI Lab, 422 Jingan Rd, 200041, Shanghai, China
| | - Jizhou Zhang
- School of Life Sciences, The Chinese University of Hong Kong, 100871, Hong Kong SAR, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, 100871, Hong Kong SAR, China
| | - Ting-Fung Chan
- School of Life Sciences, The Chinese University of Hong Kong, 100871, Hong Kong SAR, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, 100871, Hong Kong SAR, China
| | - Yu Li
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, 100871, Hong Kong SAR, China.
- The CUHK Shenzhen Research Institute, Hi-Tech Park, Nanshan, 518057, Shenzhen, China.
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8
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Xing M, Xiong Y, Zhang Y. Ku80 is indispensable for repairing DNA double-strand breaks at highly methylated sites in human HCT116 cells. DNA Repair (Amst) 2024; 134:103627. [PMID: 38219597 DOI: 10.1016/j.dnarep.2024.103627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 01/01/2024] [Accepted: 01/03/2024] [Indexed: 01/16/2024]
Abstract
DNA double-strand breaks (DSBs) are harmful to mammalian cells and a few of them can cause cell death. Accumulating DSBs in these cells to analyze their genomic distribution and their potential impact on chromatin structure is difficult. In this study, we used CRISPR to generate Ku80-/- human cells and arrested the cells in G1 phase to accumulate DSBs before conducting END-seq and Nanopore analysis. Our analysis revealed that DNA with high methylation level accumulates DSB hotspots in Ku80-/- human cells. Furthermore, we identified chromosome structural variants (SVs) using Nanopore sequencing and observed a higher number of SVs in Ku80-/- human cells. Based on our findings, we suggest that the high efficiency of Ku80 knockout in human HCT116 cells makes it a promising model for characterizing SVs in the context of 3D chromatin structure and studying the alternative-end joining (Alt-EJ) DSB repair pathway.
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Affiliation(s)
- Mengtan Xing
- Institute for Regenerative Medicine, Department of Neurosurgery, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Yanhong Xiong
- Institute for Regenerative Medicine, Department of Neurosurgery, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Yong Zhang
- Institute for Regenerative Medicine, Department of Neurosurgery, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China.
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9
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Krais JJ, Glass DJ, Chudoba I, Wang Y, Feng W, Simpson D, Patel P, Liu Z, Neumann-Domer R, Betsch RG, Bernhardy AJ, Bradbury AM, Conger J, Yueh WT, Nacson J, Pomerantz RT, Gupta GP, Testa JR, Johnson N. Genetic separation of Brca1 functions reveal mutation-dependent Polθ vulnerabilities. Nat Commun 2023; 14:7714. [PMID: 38001070 PMCID: PMC10673838 DOI: 10.1038/s41467-023-43446-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 11/09/2023] [Indexed: 11/26/2023] Open
Abstract
Homologous recombination (HR)-deficiency induces a dependency on DNA polymerase theta (Polθ/Polq)-mediated end joining, and Polθ inhibitors (Polθi) are in development for cancer therapy. BRCA1 and BRCA2 deficient cells are thought to be synthetic lethal with Polθ, but whether distinct HR gene mutations give rise to equivalent Polθ-dependence, and the events that drive lethality, are unclear. In this study, we utilized mouse models with separate Brca1 functional defects to mechanistically define Brca1-Polθ synthetic lethality. Surprisingly, homozygous Brca1 mutant, Polq-/- cells were viable, but grew slowly and had chromosomal instability. Brca1 mutant cells proficient in DNA end resection were significantly more dependent on Polθ for viability; here, treatment with Polθi elevated RPA foci, which persisted through mitosis. In an isogenic system, BRCA1 null cells were defective, but PALB2 and BRCA2 mutant cells exhibited active resection, and consequently stronger sensitivity to Polθi. Thus, DNA end resection is a critical determinant of Polθi sensitivity in HR-deficient cells, and should be considered when selecting patients for clinical studies.
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Affiliation(s)
- John J Krais
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.
- Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, 63110, USA.
| | - David J Glass
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
- Temple University, Lewis Katz School of Medicine, Philadelphia, PA, 19140, USA
| | - Ilse Chudoba
- MetaSystems Probes, GmbH, Industriestr, 68804, Altlussheim, Germany
| | - Yifan Wang
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Wanjuan Feng
- Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Dennis Simpson
- Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Pooja Patel
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Zemin Liu
- Cytogenetics Laboratory, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Ryan Neumann-Domer
- Cytogenetics Laboratory, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Robert G Betsch
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Andrea J Bernhardy
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Alice M Bradbury
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Jason Conger
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Wei-Ting Yueh
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Joseph Nacson
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Richard T Pomerantz
- Thomas Jefferson University, Sidney Kimmel Cancer Center, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA
| | - Gaorav P Gupta
- Cancer Control and Prevention Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Joseph R Testa
- Cytogenetics Laboratory, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
- Cancer Control and Prevention Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Neil Johnson
- Nuclear Dynamics Program, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.
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10
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Matos-Rodrigues G, Hisey JA, Nussenzweig A, Mirkin SM. Detection of alternative DNA structures and its implications for human disease. Mol Cell 2023; 83:3622-3641. [PMID: 37863029 DOI: 10.1016/j.molcel.2023.08.018] [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] [Received: 06/19/2023] [Revised: 08/01/2023] [Accepted: 08/16/2023] [Indexed: 10/22/2023]
Abstract
Around 3% of the genome consists of simple DNA repeats that are prone to forming alternative (non-B) DNA structures, such as hairpins, cruciforms, triplexes (H-DNA), four-stranded guanine quadruplexes (G4-DNA), and others, as well as composite RNA:DNA structures (e.g., R-loops, G-loops, and H-loops). These DNA structures are dynamic and favored by the unwinding of duplex DNA. For many years, the association of alternative DNA structures with genome function was limited by the lack of methods to detect them in vivo. Here, we review the recent advancements in the field and present state-of-the-art technologies and methods to study alternative DNA structures. We discuss the limitations of these methods as well as how they are beginning to provide insights into causal relationships between alternative DNA structures, genome function and stability, and human disease.
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Affiliation(s)
| | - Julia A Hisey
- Department of Biology, Tufts University, Medford, MA, USA
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA.
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11
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Zong D, Koussa NC, Cornwell JA, Pankajam AV, Kruhlak MJ, Wong N, Chari R, Cappell SD, Nussenzweig A. Comprehensive mapping of cell fates in microsatellite unstable cancer cells supports dual targeting of WRN and ATR. Genes Dev 2023; 37:913-928. [PMID: 37932011 PMCID: PMC10691471 DOI: 10.1101/gad.351085.123] [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: 08/18/2023] [Accepted: 10/10/2023] [Indexed: 11/08/2023]
Abstract
Addiction to the WRN helicase is a unique vulnerability of human cancers with high levels of microsatellite instability (MSI-H). However, while prolonged loss of WRN ultimately leads to cell death, little is known about how MSI-H cancers initially respond to acute loss of WRN-knowledge that would be helpful for informing clinical development of WRN targeting therapy, predicting possible resistance mechanisms, and identifying useful biomarkers of successful WRN inhibition. Here, we report the construction of an inducible ligand-mediated degradation system in which the stability of endogenous WRN protein can be rapidly and specifically tuned, enabling us to track the complete sequence of cellular events elicited by acute loss of WRN function. We found that WRN degradation leads to immediate accrual of DNA damage in a replication-dependent manner that curiously did not robustly engage checkpoint mechanisms to halt DNA synthesis. As a result, WRN-degraded MSI-H cancer cells accumulate DNA damage across multiple replicative cycles and undergo successive rounds of increasingly aberrant mitoses, ultimately triggering cell death. Of potential therapeutic importance, we found no evidence of any generalized mechanism by which MSI-H cancers could adapt to near-complete loss of WRN. However, under conditions of partial WRN degradation, addition of low-dose ATR inhibitor significantly increased their combined efficacy to levels approaching full inactivation of WRN. Overall, our results provide the first comprehensive view of molecular events linking upstream inhibition of WRN to subsequent cell death and suggest that dual targeting of WRN and ATR might be a useful strategy for treating MSI-H cancers.
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Affiliation(s)
- Dali Zong
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA;
| | - Natasha C Koussa
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - James A Cornwell
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Ajith V Pankajam
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Michael J Kruhlak
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Nancy Wong
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Raj Chari
- Genome Modification Core, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21701, USA
| | - Steven D Cappell
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA;
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12
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Wu J, Liu Y, Zhangding Z, Liu X, Ai C, Gan T, Liang H, Guo Y, Chen M, Liu Y, Yin J, Zhang W, Hu J. Cohesin maintains replication timing to suppress DNA damage on cancer genes. Nat Genet 2023; 55:1347-1358. [PMID: 37500731 DOI: 10.1038/s41588-023-01458-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 06/26/2023] [Indexed: 07/29/2023]
Abstract
Cohesin loss-of-function mutations are frequently observed in tumors, but the mechanism underlying its role in tumorigenesis is unclear. Here, we found that depletion of RAD21, a core subunit of cohesin, leads to massive genome-wide DNA breaks and 147 translocation hotspot genes, co-mutated with cohesin in multiple cancers. Increased DNA damages are independent of RAD21-loss-induced transcription alteration and loop anchor disruption. However, damage-induced chromosomal translocations coincide with the asymmetrically distributed Okazaki fragments of DNA replication, suggesting that RAD21 depletion causes replication stresses evidenced by the slower replication speed and increased stalled forks. Mechanistically, approximately 30% of the human genome exhibits an earlier replication timing after RAD21 depletion, caused by the early initiation of >900 extra dormant origins. Correspondingly, most translocation hotspot genes lie in timing-altered regions. Therefore, we conclude that cohesin dysfunction causes replication stresses induced by excessive DNA replication initiation, resulting in gross DNA damages that may promote tumorigenesis.
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Affiliation(s)
- Jinchun Wu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Yang Liu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Zhengrong Zhangding
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Xuhao Liu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Chen Ai
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Tingting Gan
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Haoxin Liang
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Yuefeng Guo
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Mohan Chen
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Yiyang Liu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Jianhang Yin
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Weiwei Zhang
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China
| | - Jiazhi Hu
- The MOE Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Center for Life Sciences, Genome Editing Research Center, Peking University, Beijing, China.
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13
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Zong D, Koussa NC, Cornwell JA, Pankajam AV, Kruhlak MJ, Wong N, Chari R, Cappell SD, Nussenzweig A. Comprehensive mapping of cell fates in microsatellite unstable cancer cells support dual targe6ng of WRN and ATR. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.28.550976. [PMID: 37662356 PMCID: PMC10473727 DOI: 10.1101/2023.07.28.550976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Addiction to the WRN helicase is a unique vulnerability of human cancers with high levels of microsatellite instability (MSI-H). However, while prolonged loss of WRN ultimately leads to cell death, little is known about how MSI-H cancers initially respond to acute loss of WRN, knowledge that would be helpful for informing clinical development of WRN-targeting therapy, predicting possible resistance mechanisms, and identifying useful biomarkers of successful WRN inhibition. Here, we report the construction of an inducible ligand-mediated degradation system wherein the stability of endogenous WRN protein can be rapidly and specifically tuned, enabling us to track the complete sequence of cellular events elicited by acute loss of WRN function. We find that WRN degradation leads to immediate accrual of DNA damage in a replication-dependent manner that curiously did not robustly engage checkpoint mechanisms to halt DNA synthesis. As a result, WRN-degraded MSI-H cancer cells accumulate DNA damage across multiple replicative cycles and undergo successive rounds of increasingly aberrant mitoses, ultimately triggering cell death. Of potential therapeutic importance, we find no evidence of any generalized mechanism by which MSI-H cancers could adapt to near-complete loss of WRN. However, under conditions of partial WRN degradation, addition of low dose ATR inhibitor significantly increased their combined efficacy to levels approaching full inactivation of WRN. Overall, our results provided the first comprehensive view of molecular events linking upstream inhibition of WRN to subsequent cell death and suggested a potential therapeutical rationale for dual targeting of WRN and ATR.
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Affiliation(s)
- Dali Zong
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Natasha C. Koussa
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - James A. Cornwell
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ajith V. Pankajam
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Michael J. Kruhlak
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Nancy Wong
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Raj Chari
- Genome Modification Core, Frederick National Lab for Cancer Research, Frederick, MD, USA
| | - Steven D. Cappell
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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14
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Saayman X, Graham E, Nathan WJ, Nussenzweig A, Esashi F. Centromeres as universal hotspots of DNA breakage, driving RAD51-mediated recombination during quiescence. Mol Cell 2023; 83:523-538.e7. [PMID: 36702125 PMCID: PMC10009740 DOI: 10.1016/j.molcel.2023.01.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 10/07/2022] [Accepted: 01/03/2023] [Indexed: 01/27/2023]
Abstract
Centromeres are essential for chromosome segregation in most animals and plants yet are among the most rapidly evolving genome elements. The mechanisms underlying this paradoxical phenomenon remain enigmatic. Here, we report that human centromeres innately harbor a striking enrichment of DNA breaks within functionally active centromere regions. Establishing a single-cell imaging strategy that enables comparative assessment of DNA breaks at repetitive regions, we show that centromeric DNA breaks are induced not only during active cellular proliferation but also de novo during quiescence. Markedly, centromere DNA breaks in quiescent cells are resolved enzymatically by the evolutionarily conserved RAD51 recombinase, which in turn safeguards the specification of functional centromeres. This study highlights the innate fragility of centromeres, which may have been co-opted over time to reinforce centromere specification while driving rapid evolution. The findings also provide insights into how fragile centromeres are likely to contribute to human disease.
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Affiliation(s)
- Xanita Saayman
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Emily Graham
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - William J Nathan
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892-4254, USA
| | - Andre Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD 20892-4254, USA
| | - Fumiko Esashi
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
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15
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Abstract
In most organisms, the whole genome is maintained throughout the life span. However, exceptions occur in some species where the genome is reduced during development through a process known as programmed DNA elimination (PDE). In the human and pig parasite Ascaris, PDE occurs during the 4 to 16 cell stages of embryogenesis, when germline chromosomes are fragmented and specific DNA sequences are reproducibly lost in all somatic cells. PDE was identified in Ascaris over 120 years ago, but little was known about its molecular details until recently. Genome sequencing revealed that approximately 1,000 germline-expressed genes are eliminated in Ascaris, suggesting PDE is a gene silencing mechanism. All germline chromosome ends are removed and remodeled during PDE. In addition, PDE increases the number of chromosomes in the somatic genome by splitting many germline chromosomes. Comparative genomics indicates that these germline chromosomes arose from fusion events. PDE separates these chromosomes at the fusion sites. These observations indicate that PDE plays a role in chromosome karyotype and evolution. Furthermore, comparative analysis of PDE in other parasitic and free-living nematodes illustrates conserved features of PDE, suggesting it has important biological significance. We summarize what is known about PDE in Ascaris and its relatives. We also discuss other potential functions, mechanisms, and the evolution of PDE in these parasites of humans and animals of veterinary importance.
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16
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Pollina EA, Gilliam DT, Landau AT, Lin C, Pajarillo N, Davis CP, Harmin DA, Yap EL, Vogel IR, Griffith EC, Nagy MA, Ling E, Duffy EE, Sabatini BL, Weitz CJ, Greenberg ME. A NPAS4-NuA4 complex couples synaptic activity to DNA repair. Nature 2023; 614:732-741. [PMID: 36792830 PMCID: PMC9946837 DOI: 10.1038/s41586-023-05711-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 01/05/2023] [Indexed: 02/17/2023]
Abstract
Neuronal activity is crucial for adaptive circuit remodelling but poses an inherent risk to the stability of the genome across the long lifespan of postmitotic neurons1-5. Whether neurons have acquired specialized genome protection mechanisms that enable them to withstand decades of potentially damaging stimuli during periods of heightened activity is unknown. Here we identify an activity-dependent DNA repair mechanism in which a new form of the NuA4-TIP60 chromatin modifier assembles in activated neurons around the inducible, neuronal-specific transcription factor NPAS4. We purify this complex from the brain and demonstrate its functions in eliciting activity-dependent changes to neuronal transcriptomes and circuitry. By characterizing the landscape of activity-induced DNA double-strand breaks in the brain, we show that NPAS4-NuA4 binds to recurrently damaged regulatory elements and recruits additional DNA repair machinery to stimulate their repair. Gene regulatory elements bound by NPAS4-NuA4 are partially protected against age-dependent accumulation of somatic mutations. Impaired NPAS4-NuA4 signalling leads to a cascade of cellular defects, including dysregulated activity-dependent transcriptional responses, loss of control over neuronal inhibition and genome instability, which all culminate to reduce organismal lifespan. In addition, mutations in several components of the NuA4 complex are reported to lead to neurodevelopmental and autism spectrum disorders. Together, these findings identify a neuronal-specific complex that couples neuronal activity directly to genome preservation, the disruption of which may contribute to developmental disorders, neurodegeneration and ageing.
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Affiliation(s)
- Elizabeth A Pollina
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO, USA
| | - Daniel T Gilliam
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Andrew T Landau
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Cindy Lin
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Naomi Pajarillo
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | | | - David A Harmin
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Ee-Lynn Yap
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Ian R Vogel
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Eric C Griffith
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - M Aurel Nagy
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Emi Ling
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Erin E Duffy
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Bernardo L Sabatini
- Department of Neurobiology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Charles J Weitz
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
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17
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Zagelbaum J, Schooley A, Zhao J, Schrank BR, Callen E, Zha S, Gottesman ME, Nussenzweig A, Rabadan R, Dekker J, Gautier J. Multiscale reorganization of the genome following DNA damage facilitates chromosome translocations via nuclear actin polymerization. Nat Struct Mol Biol 2023; 30:99-106. [PMID: 36564591 PMCID: PMC10104780 DOI: 10.1038/s41594-022-00893-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 11/04/2022] [Indexed: 12/24/2022]
Abstract
Nuclear actin-based movements have been shown to orchestrate clustering of DNA double-strand breaks (DSBs) into homology-directed repair domains. Here we describe multiscale three-dimensional genome reorganization following DNA damage and analyze the contribution of the nuclear WASP-ARP2/3-actin pathway toward chromatin topology alterations and pathologic repair. Hi-C analysis reveals genome-wide, DNA damage-induced chromatin compartment flips facilitated by ARP2/3 that enrich for open, A compartments. Damage promotes interactions between DSBs, which in turn facilitate aberrant, actin-dependent intra- and inter-chromosomal rearrangements. Our work establishes that clustering of resected DSBs into repair domains by nuclear actin assembly is coordinated with multiscale alterations in genome architecture that enable homology-directed repair while also increasing nonhomologous end-joining-dependent translocation frequency.
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Affiliation(s)
- Jennifer Zagelbaum
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Integrated Program in Cellular, Molecular, and Biomedical Studies, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Allana Schooley
- Department of Systems Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Junfei Zhao
- Department of Systems Biology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Benjamin R Schrank
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Elsa Callen
- Laboratory of Genome Integrity, National Institutes of Health, Bethesda, MD, USA
| | - Shan Zha
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Department of Pathology and Cell Biology and Department of Pediatrics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Max E Gottesman
- Department of Biochemistry and Biophysics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Institutes of Health, Bethesda, MD, USA
| | - Raul Rabadan
- Department of Systems Biology, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Job Dekker
- Department of Systems Biology, University of Massachusetts Medical School, Worcester, MA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Jean Gautier
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
- Herbert Irving Comprehensive Cancer Center, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
- Department of Genetics and Development, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
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18
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Dockendorff TC, Estrem B, Reed J, Simmons JR, Zadegan SB, Zagoskin MV, Terta V, Villalobos E, Seaberry EM, Wang J. The nematode Oscheius tipulae as a genetic model for programmed DNA elimination. Curr Biol 2022; 32:5083-5098.e6. [PMID: 36379215 PMCID: PMC9729473 DOI: 10.1016/j.cub.2022.10.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/05/2022] [Accepted: 10/19/2022] [Indexed: 11/16/2022]
Abstract
Programmed DNA elimination (PDE) is a notable exception to the paradigm of genome integrity. In metazoa, PDE often occurs coincident with germline to somatic cell differentiation. During PDE, portions of genomic DNA are lost, resulting in reduced somatic genomes. Prior studies have described the sequences lost, as well as chromosome behavior, during metazoan PDE. However, a system for studying the mechanisms and consequences of PDE in metazoa is lacking. Here, we present a functional and genetic model for PDE in the free-living Rhabditidae nematode Oscheius tipulae, a family that also includes Caenorhabditis elegans. O. tipulae was recently suggested to eliminate DNA. Using staged embryos and DNA FISH, we showed that O. tipulae PDE occurs during embryogenesis at the 8-16 cell stages. We identified a conserved motif, named Sequence For Elimination (SFE), for all 12 break sites on the six chromosomes at the junctions of retained and eliminated DNA. SFE mutants exhibited a "fail-to-eliminate" phenotype only at the modified sites. END-seq revealed that breaks can occur at multiple positions within the SFE, with extensive end resection followed by telomere addition to both retained and eliminated ends. We identified many functional SFEs at the chromosome ends through END-seq in the wild-type embryos, genome sequencing of SFE mutants, and comparative genomics of 23 wild isolates. We suggest that these alternative SFEs provide flexibility in the sequences eliminated and a fail-safe mechanism for PDE. These studies establish O. tipulae as a new, attractive model for studying the mechanisms and consequences of PDE in a metazoan.
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Affiliation(s)
- Thomas C Dockendorff
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Brandon Estrem
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Jordan Reed
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - James R Simmons
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Sobhan Bahrami Zadegan
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA
| | - Maxim V Zagoskin
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Vincent Terta
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Eduardo Villalobos
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Erin M Seaberry
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Jianbin Wang
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA; UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA.
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19
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Matos-Rodrigues G, van Wietmarschen N, Wu W, Tripathi V, Koussa NC, Pavani R, Nathan WJ, Callen E, Belinky F, Mohammed A, Napierala M, Usdin K, Ansari AZ, Mirkin SM, Nussenzweig A. S1-END-seq reveals DNA secondary structures in human cells. Mol Cell 2022; 82:3538-3552.e5. [PMID: 36075220 PMCID: PMC9547894 DOI: 10.1016/j.molcel.2022.08.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/25/2022] [Accepted: 08/04/2022] [Indexed: 11/15/2022]
Abstract
DNA becomes single stranded (ssDNA) during replication, transcription, and repair. Transiently formed ssDNA segments can adopt alternative conformations, including cruciforms, triplexes, and quadruplexes. To determine whether there are stable regions of ssDNA in the human genome, we utilized S1-END-seq to convert ssDNA regions to DNA double-strand breaks, which were then processed for high-throughput sequencing. This approach revealed two predominant non-B DNA structures: cruciform DNA formed by expanded (TA)n repeats that accumulate in microsatellite unstable human cancer cell lines and DNA triplexes (H-DNA) formed by homopurine/homopyrimidine mirror repeats common across a variety of cell lines. We show that H-DNA is enriched during replication, that its genomic location is highly conserved, and that H-DNA formed by (GAA)n repeats can be disrupted by treatment with a (GAA)n-binding polyamide. Finally, we show that triplex-forming repeats are hotspots for mutagenesis. Our results identify dynamic DNA secondary structures in vivo that contribute to elevated genome instability.
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Affiliation(s)
| | | | - Wei Wu
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Veenu Tripathi
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Natasha C Koussa
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Raphael Pavani
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - William J Nathan
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Elsa Callen
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Frida Belinky
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Ashraf Mohammed
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Marek Napierala
- Department of Neurology, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd, Dallas, TX 75390, USA
| | - Karen Usdin
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Aseem Z Ansari
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN, USA
| | | | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA.
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20
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Abstract
TOP1 CAD-seq enables mapping of TOP1 sites of covalent engagement with DNA. The procedure depends upon enrichment of DNA-covalent adducts using chaotropic salts and immunoprecipitation with an antibody specific for TOP1. Here, we describe a step-by-step protocol compatible with Illumina sequencing and bioinformatic pipeline for preliminary data analysis. Compared to other approaches for the genomic study of topoisomerases, TOP1 CAD-seq provides information about active TOP1 engaged on the DNA, taking advantage of low background due to absence of crosslinking. For complete details on the use and execution of this protocol, please refer to Das et al. (2022). TOP1 CAD-seq maps sites of topoisomerase 1 catalytic engagement with the DNA The absence of a cross-linking step reduces the background signal The method is high throughput and takes no longer than a regular ChIP-seq protocol The method can be used as a proxy to assess the level of supercoiling in the genome
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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21
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Gao LA, Wilkinson ME, Strecker J, Makarova KS, Macrae RK, Koonin EV, Zhang F. Prokaryotic innate immunity through pattern recognition of conserved viral proteins. Science 2022; 377:eabm4096. [PMID: 35951700 PMCID: PMC10028730 DOI: 10.1126/science.abm4096] [Citation(s) in RCA: 96] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Many organisms have evolved specialized immune pattern-recognition receptors, including nucleotide-binding oligomerization domain-like receptors (NLRs) of the STAND superfamily that are ubiquitous in plants, animals, and fungi. Although the roles of NLRs in eukaryotic immunity are well established, it is unknown whether prokaryotes use similar defense mechanisms. Here, we show that antiviral STAND (Avs) homologs in bacteria and archaea detect hallmark viral proteins, triggering Avs tetramerization and the activation of diverse N-terminal effector domains, including DNA endonucleases, to abrogate infection. Cryo-electron microscopy reveals that Avs sensor domains recognize conserved folds, active-site residues, and enzyme ligands, allowing a single Avs receptor to detect a wide variety of viruses. These findings extend the paradigm of pattern recognition of pathogen-specific proteins across all three domains of life.
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Affiliation(s)
- Linyi Alex Gao
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- McGovern Institute for Brain Research
- Department of Brain and Cognitive Sciences
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Society of Fellows, Harvard University, Cambridge, MA 02138, USA
- Correspondence: (F.Z.) or (L.A.G.)
| | - Max E. Wilkinson
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- McGovern Institute for Brain Research
- Department of Brain and Cognitive Sciences
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jonathan Strecker
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- McGovern Institute for Brain Research
- Department of Brain and Cognitive Sciences
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Kira S. Makarova
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Rhiannon K. Macrae
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- McGovern Institute for Brain Research
- Department of Brain and Cognitive Sciences
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Feng Zhang
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- McGovern Institute for Brain Research
- Department of Brain and Cognitive Sciences
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Correspondence: (F.Z.) or (L.A.G.)
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22
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Weber Boutros S, Unni VK, Raber J. An Adaptive Role for DNA Double-Strand Breaks in Hippocampus-Dependent Learning and Memory. Int J Mol Sci 2022; 23:8352. [PMID: 35955487 PMCID: PMC9368779 DOI: 10.3390/ijms23158352] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 12/10/2022] Open
Abstract
DNA double-strand breaks (DSBs), classified as the most harmful type of DNA damage based on the complexity of repair, lead to apoptosis or tumorigenesis. In aging, DNA damage increases and DNA repair decreases. This is exacerbated in disease, as post-mortem tissue from patients diagnosed with mild cognitive impairment (MCI) or Alzheimer's disease (AD) show increased DSBs. A novel role for DSBs in immediate early gene (IEG) expression, learning, and memory has been suggested. Inducing neuronal activity leads to increases in DSBs and upregulation of IEGs, while increasing DSBs and inhibiting DSB repair impairs long-term memory and alters IEG expression. Consistent with this pattern, mice carrying dominant AD mutations have increased baseline DSBs, and impaired DSB repair is observed. These data suggest an adaptive role for DSBs in the central nervous system and dysregulation of DSBs and/or repair might drive age-related cognitive decline (ACD), MCI, and AD. In this review, we discuss the adaptive role of DSBs in hippocampus-dependent learning, memory, and IEG expression. We summarize IEGs, the history of DSBs, and DSBs in synaptic plasticity, aging, and AD. DSBs likely have adaptive functions in the brain, and even subtle alterations in their formation and repair could alter IEGs, learning, and memory.
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Affiliation(s)
- Sydney Weber Boutros
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, USA;
| | - Vivek K. Unni
- Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA;
- Jungers Center for Neurosciences Research, Oregon Health & Science University, Portland, OR 97239, USA
- Oregon Health & Science University Parkinson Center, Portland, OR 97239, USA
| | - Jacob Raber
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, USA;
- Department of Neurology, Oregon Health & Science University, Portland, OR 97239, USA;
- Department of Radiation Medicine, Oregon Health & Science University, Portland, OR 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, USA
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23
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Fowler FC, Chen BR, Zolnerowich N, Wu W, Pavani R, Paiano J, Peart C, Chen Z, Nussenzweig A, Sleckman BP, Tyler JK. DNA-PK promotes DNA end resection at DNA double strand breaks in G 0 cells. eLife 2022; 11:e74700. [PMID: 35575473 PMCID: PMC9122494 DOI: 10.7554/elife.74700] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 05/06/2022] [Indexed: 11/16/2022] Open
Abstract
DNA double-strand break (DSB) repair by homologous recombination is confined to the S and G2 phases of the cell cycle partly due to 53BP1 antagonizing DNA end resection in G1 phase and non-cycling quiescent (G0) cells where DSBs are predominately repaired by non-homologous end joining (NHEJ). Unexpectedly, we uncovered extensive MRE11- and CtIP-dependent DNA end resection at DSBs in G0 murine and human cells. A whole genome CRISPR/Cas9 screen revealed the DNA-dependent kinase (DNA-PK) complex as a key factor in promoting DNA end resection in G0 cells. In agreement, depletion of FBXL12, which promotes ubiquitylation and removal of the KU70/KU80 subunits of DNA-PK from DSBs, promotes even more extensive resection in G0 cells. In contrast, a requirement for DNA-PK in promoting DNA end resection in proliferating cells at the G1 or G2 phase of the cell cycle was not observed. Our findings establish that DNA-PK uniquely promotes DNA end resection in G0, but not in G1 or G2 phase cells, which has important implications for DNA DSB repair in quiescent cells.
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Affiliation(s)
- Faith C Fowler
- Weill Cornell Medicine Pharmacology Graduate ProgramNew YorkUnited States
- Weill Cornell Medicine, Department of Pathology and Laboratory MedicineNew YorkUnited States
| | - Bo-Ruei Chen
- Department of Medicine, Division of Hematology and Oncology, O'Neal Comprehensive Cancer Center, University of Alabama at BirminghamBirminghamUnited States
| | | | - Wei Wu
- Laboratory of Genome Integrity, National Cancer InstituteBethesdaUnited States
| | - Raphael Pavani
- Laboratory of Genome Integrity, National Cancer InstituteBethesdaUnited States
| | - Jacob Paiano
- Laboratory of Genome Integrity, National Cancer InstituteBethesdaUnited States
| | - Chelsea Peart
- Weill Cornell Medicine, Department of Pathology and Laboratory MedicineNew YorkUnited States
| | - Zulong Chen
- Weill Cornell Medicine, Department of Pathology and Laboratory MedicineNew YorkUnited States
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer InstituteBethesdaUnited States
| | - Barry P Sleckman
- Department of Medicine, Division of Hematology and Oncology, O'Neal Comprehensive Cancer Center, University of Alabama at BirminghamBirminghamUnited States
| | - Jessica K Tyler
- Weill Cornell Medicine, Department of Pathology and Laboratory MedicineNew YorkUnited States
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24
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Rawal CC, Butova NL, Mitra A, Chiolo I. An Expanding Toolkit for Heterochromatin Repair Studies. Genes (Basel) 2022; 13:genes13030529. [PMID: 35328082 PMCID: PMC8955653 DOI: 10.3390/genes13030529] [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: 01/23/2022] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 12/04/2022] Open
Abstract
Pericentromeric heterochromatin is mostly composed of repetitive DNA sequences prone to aberrant recombination. Cells have developed highly specialized mechanisms to enable ‘safe’ homologous recombination (HR) repair while preventing aberrant recombination in this domain. Understanding heterochromatin repair responses is essential to understanding the critical mechanisms responsible for genome integrity and tumor suppression. Here, we review the tools, approaches, and methods currently available to investigate double-strand break (DSB) repair in pericentromeric regions, and also suggest how technologies recently developed for euchromatin repair studies can be adapted to characterize responses in heterochromatin. With this ever-growing toolkit, we are witnessing exciting progress in our understanding of how the ‘dark matter’ of the genome is repaired, greatly improving our understanding of genome stability mechanisms.
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25
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Olbrich T, Vega-Sendino M, Tillo D, Wu W, Zolnerowich N, Pavani R, Tran AD, Domingo CN, Franco M, Markiewicz-Potoczny M, Pegoraro G, FitzGerald PC, Kruhlak MJ, Lazzerini-Denchi E, Nora EP, Nussenzweig A, Ruiz S. CTCF is a barrier for 2C-like reprogramming. Nat Commun 2021; 12:4856. [PMID: 34381034 PMCID: PMC8358036 DOI: 10.1038/s41467-021-25072-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 07/17/2021] [Indexed: 01/28/2023] Open
Abstract
Totipotent cells have the ability to generate embryonic and extra-embryonic tissues. Interestingly, a rare population of cells with totipotent-like potential, known as 2 cell (2C)-like cells, has been identified within ESC cultures. They arise from ESC and display similar features to those found in the 2C embryo. However, the molecular determinants of 2C-like conversion have not been completely elucidated. Here, we show that the CCCTC-binding factor (CTCF) is a barrier for 2C-like reprogramming. Indeed, forced conversion to a 2C-like state by the transcription factor DUX is associated with DNA damage at a subset of CTCF binding sites. Depletion of CTCF in ESC efficiently promotes spontaneous and asynchronous conversion to a 2C-like state and is reversible upon restoration of CTCF levels. This phenotypic reprogramming is specific to pluripotent cells as neural progenitor cells do not show 2C-like conversion upon CTCF-depletion. Furthermore, we show that transcriptional activation of the ZSCAN4 cluster is necessary for successful 2C-like reprogramming. In summary, we reveal an unexpected relationship between CTCF and 2C-like reprogramming.
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Affiliation(s)
- Teresa Olbrich
- Laboratory of Genome Integrity, CCR, NCI, NIH, Bethesda, MD, USA
| | | | | | - Wei Wu
- Laboratory of Genome Integrity, CCR, NCI, NIH, Bethesda, MD, USA
| | | | - Raphael Pavani
- Laboratory of Genome Integrity, CCR, NCI, NIH, Bethesda, MD, USA
| | - Andy D Tran
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, MD, USA
| | | | - Mariajose Franco
- Laboratory of Genome Integrity, CCR, NCI, NIH, Bethesda, MD, USA
| | | | - Gianluca Pegoraro
- Laboratory of Receptor Biology and Gene Expression, CCR, NCI, NIH, Bethesda, MD, USA
| | | | - Michael J Kruhlak
- Laboratory of Cancer Biology and Genetics, CCR, NCI, NIH, Bethesda, MD, USA
| | | | - Elphege P Nora
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, USA
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
| | | | - Sergio Ruiz
- Laboratory of Genome Integrity, CCR, NCI, NIH, Bethesda, MD, USA.
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26
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The WRN helicase: resolving a new target in microsatellite unstable cancers. Curr Opin Genet Dev 2021; 71:34-38. [PMID: 34284257 DOI: 10.1016/j.gde.2021.06.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/22/2021] [Accepted: 06/29/2021] [Indexed: 11/22/2022]
Abstract
One of the goals of precision medicine is to uncover selective vulnerabilities in various cancers. A notable success has been the development of PARP inhibitors for the treatment of breast and ovarian cancers with mutations in BRCA genes. Only two years ago, it was discovered that cancers with microsatellite instability (MSI) were selectively dependent on the RecQ DNA helicase WRN. Subsequently, the molecular mechanism underlying WRN dependency in MSI cancers was uncovered. Here, we review how these developments have led to a promising new drug target in MSI cancers.
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27
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Wu W, Hill SE, Nathan WJ, Paiano J, Callen E, Wang D, Shinoda K, van Wietmarschen N, Colón-Mercado JM, Zong D, De Pace R, Shih HY, Coon S, Parsadanian M, Pavani R, Hanzlikova H, Park S, Jung SK, McHugh PJ, Canela A, Chen C, Casellas R, Caldecott KW, Ward ME, Nussenzweig A. Neuronal enhancers are hotspots for DNA single-strand break repair. Nature 2021; 593:440-444. [PMID: 33767446 PMCID: PMC9827709 DOI: 10.1038/s41586-021-03468-5] [Citation(s) in RCA: 113] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 03/17/2021] [Indexed: 02/01/2023]
Abstract
Defects in DNA repair frequently lead to neurodevelopmental and neurodegenerative diseases, underscoring the particular importance of DNA repair in long-lived post-mitotic neurons1,2. The cellular genome is subjected to a constant barrage of endogenous DNA damage, but surprisingly little is known about the identity of the lesion(s) that accumulate in neurons and whether they accrue throughout the genome or at specific loci. Here we show that post-mitotic neurons accumulate unexpectedly high levels of DNA single-strand breaks (SSBs) at specific sites within the genome. Genome-wide mapping reveals that SSBs are located within enhancers at or near CpG dinucleotides and sites of DNA demethylation. These SSBs are repaired by PARP1 and XRCC1-dependent mechanisms. Notably, deficiencies in XRCC1-dependent short-patch repair increase DNA repair synthesis at neuronal enhancers, whereas defects in long-patch repair reduce synthesis. The high levels of SSB repair in neuronal enhancers are therefore likely to be sustained by both short-patch and long-patch processes. These data provide the first evidence of site- and cell-type-specific SSB repair, revealing unexpected levels of localized and continuous DNA breakage in neurons. In addition, they suggest an explanation for the neurodegenerative phenotypes that occur in patients with defective SSB repair.
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Affiliation(s)
- Wei Wu
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Sarah E Hill
- National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - William J Nathan
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA.,Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Jacob Paiano
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Elsa Callen
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Dongpeng Wang
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Kenta Shinoda
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | | | | | - Dali Zong
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Raffaella De Pace
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - Han-Yu Shih
- National Eye Institute, NIH, Bethesda, MD, USA
| | - Steve Coon
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - Maia Parsadanian
- National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Raphael Pavani
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Hana Hanzlikova
- Department of Genome Dynamics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic.,Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Solji Park
- Lymphocyte Nuclear Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases and National Cancer Institute, NIH, Bethesda, MD, USA.,NIH Regulome Project, NIH, Bethesda, MD, USA
| | - Seol Kyoung Jung
- Lymphocyte Nuclear Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases and National Cancer Institute, NIH, Bethesda, MD, USA.,NIH Regulome Project, NIH, Bethesda, MD, USA
| | - Peter J McHugh
- Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Andres Canela
- The Hakubi Center for Advanced Research and Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Chongyi Chen
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Rafael Casellas
- Lymphocyte Nuclear Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases and National Cancer Institute, NIH, Bethesda, MD, USA.,NIH Regulome Project, NIH, Bethesda, MD, USA
| | - Keith W Caldecott
- Department of Genome Dynamics, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic. .,Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK.
| | - Michael E Ward
- National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA.
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA.
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28
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Wang J. Genomics of the Parasitic Nematode Ascaris and Its Relatives. Genes (Basel) 2021; 12:493. [PMID: 33800545 PMCID: PMC8065839 DOI: 10.3390/genes12040493] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/22/2021] [Accepted: 03/26/2021] [Indexed: 12/18/2022] Open
Abstract
Nematodes of the genus Ascaris are important parasites of humans and swine, and the phylogenetically related genera (Parascaris, Toxocara, and Baylisascaris) infect mammals of veterinary interest. Over the last decade, considerable genomic resources have been established for Ascaris, including complete germline and somatic genomes, comprehensive mRNA and small RNA transcriptomes, as well as genome-wide histone and chromatin data. These datasets provide a major resource for studies on the basic biology of these parasites and the host-parasite relationship. Ascaris and its relatives undergo programmed DNA elimination, a highly regulated process where chromosomes are fragmented and portions of the genome are lost in embryonic cells destined to adopt a somatic fate, whereas the genome remains intact in germ cells. Unlike many model organisms, Ascaris transcription drives early development beginning prior to pronuclear fusion. Studies on Ascaris demonstrated a complex small RNA network even in the absence of a piRNA pathway. Comparative genomics of these ascarids has provided perspectives on nematode sex chromosome evolution, programmed DNA elimination, and host-parasite coevolution. The genomic resources enable comparison of proteins across diverse species, revealing many new potential drug targets that could be used to control these parasitic nematodes.
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Affiliation(s)
- Jianbin Wang
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA;
- UT-Oak Ridge National Laboratory Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA
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