1
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Kitaoka M, Yamashita YM. Running the gauntlet: challenges to genome integrity in spermiogenesis. Nucleus 2024; 15:2339220. [PMID: 38594652 PMCID: PMC11005813 DOI: 10.1080/19491034.2024.2339220] [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: 02/23/2024] [Accepted: 04/02/2024] [Indexed: 04/11/2024] Open
Abstract
Species' continuity depends on gametogenesis to produce the only cell types that can transmit genetic information across generations. Spermiogenesis, which encompasses post-meiotic, haploid stages of male gametogenesis, is a process that leads to the formation of sperm cells well-known for their motility. Spermiogenesis faces three major challenges. First, after two rounds of meiotic divisions, the genome lacks repair templates (no sister chromatids, no homologous chromosomes), making it incredibly vulnerable to any genomic insults over an extended time (typically days-weeks). Second, the sperm genome becomes transcriptionally silent, making it difficult to respond to new perturbations as spermiogenesis progresses. Third, the histone-to-protamine transition, which is essential to package the sperm genome, counterintuitively involves DNA break formation. How spermiogenesis handles these challenges remains poorly understood. In this review, we discuss each challenge and their intersection with the biology of protamines. Finally, we discuss the implication of protamines in the process of evolution.
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Affiliation(s)
- Maiko Kitaoka
- Whitehead Institute for Biomedical Research and Howard Hughes Medical Institute, Cambridge, MA, USA
| | - Yukiko M. Yamashita
- Whitehead Institute for Biomedical Research and Howard Hughes Medical Institute, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
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2
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Xia Y, Li D, Chen T, Pan S, Huang H, Zhang W, Liang Y, Fu Y, Peng Z, Zhang H, Zhang L, Peng S, Shi R, He X, Zhou S, Jiao W, Zhao X, Wu X, Zhou L, Zhou J, Ouyang Q, Tian Y, Jiang X, Zhou Y, Tang S, Shen J, Ohshima K, Tan Z. Microsatellite density landscapes illustrate short tandem repeats aggregation in the complete reference human genome. BMC Genomics 2024; 25:960. [PMID: 39402450 PMCID: PMC11477012 DOI: 10.1186/s12864-024-10843-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2024] [Accepted: 09/26/2024] [Indexed: 10/19/2024] Open
Abstract
BACKGROUND Microsatellites are increasingly realized to have biological significance in human genome and health in past decades, the assembled complete reference sequence of human genome T2T-CHM13 brought great help for a comprehensive study of short tandem repeats in the human genome. RESULTS Microsatellites density landscapes of all 24 chromosomes were built here for the first complete reference sequence of human genome T2T-CHM13. These landscapes showed that short tandem repeats (STRs) are prone to aggregate characteristically to form a large number of STRs density peaks. We classified 8,823 High Microsatellites Density Peaks (HMDPs), 35,257 Middle Microsatellites Density Peaks (MMDPs) and 199, 649 Low Microsatellites Density Peaks (LMDPs) on the 24 chromosomes; and also classified the motif types of every microsatellites density peak. These STRs density aggregation peaks are mainly composing of a single motif, and AT is the most dominant motif, followed by AATGG and CCATT motifs. And 514 genomic regions were characterized by microsatellite density feature in the full T2T-CHM13 genome. CONCLUSIONS These landscape maps exhibited that microsatellites aggregate in many genomic positions to form a large number of microsatellite density peaks with composing of mainly single motif type in the complete reference genome, indicating that the local microsatellites density varies enormously along the every chromosome of T2T-CHM13.
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Affiliation(s)
- Yun Xia
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Douyue Li
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Tingyi Chen
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Saichao Pan
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Hanrou Huang
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Wenxiang Zhang
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Yulin Liang
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Yongzhuo Fu
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Zhuli Peng
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Hongxi Zhang
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Liang Zhang
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Shan Peng
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Ruixue Shi
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Xingxin He
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Siqian Zhou
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Weili Jiao
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Xiangyan Zhao
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Xiaolong Wu
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Lan Zhou
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Jingyu Zhou
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Qingjian Ouyang
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - You Tian
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Xiaoping Jiang
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Yi Zhou
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Shiying Tang
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | - Junxiong Shen
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China
| | | | - Zhongyang Tan
- Bioinformatic Center, College of Biology, Hunan University, Lushan Road (S), Yuelu District, Changsha, 410082, China.
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3
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Lebedin M, de la Rosa K. Diversification of Antibodies: From V(D)J Recombination to Somatic Exon Shuffling. Annu Rev Cell Dev Biol 2024; 40:265-281. [PMID: 39356809 DOI: 10.1146/annurev-cellbio-112122-030835] [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] [Indexed: 10/04/2024]
Abstract
Antibodies that gain specificity by a large insert encoding for an extra domain were described for the first time in 2016. In malaria-exposed individuals, an exon deriving from the leukocyte-associated immunoglobulin-like 1 (LAIR1) gene integrated via a copy-and-paste insertion into the immunoglobulin heavy chain encoding region. A few years later, a second example was identified, namely a dual exon integration from the leukocyte immunoglobulin-like receptor B1 (LILRB1) gene that is located in close proximity to LAIR1. A dedicated high-throughput characterization of chimeric immunoglobulin heavy chain transcripts unraveled, that insertions from distant genomic regions (including mitochondrial DNA) can contribute to human antibody diversity. This review describes the modalities of insert-containing antibodies. The role of known DNA mobility aspects, such as genomic translocation, gene conversion, and DNA fragility, is discussed in the context of insert-antibody generation. Finally, the review covers why insert antibodies were omitted from the past repertoire analyses and how insert antibodies can contribute to protective immunity or an autoreactive response.
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Affiliation(s)
- Mikhail Lebedin
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany;
- Charité - Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt Universität zu Berlin, Berlin, Germany
| | - Kathrin de la Rosa
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany;
- Berlin Institute of Health at Charité - Universitätsmedizin Berlin, Berlin, Germany
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4
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Pytko KG, Dannenberg RL, Eckert KA, Hedglin M. Replication of [AT/TA] 25 Microsatellite Sequences by Human DNA Polymerase δ Holoenzymes Is Dependent on dNTP and RPA Levels. Biochemistry 2024; 63:969-983. [PMID: 38623046 DOI: 10.1021/acs.biochem.4c00006] [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] [Indexed: 04/17/2024]
Abstract
Fragile sites are unstable genomic regions that are prone to breakage during stressed DNA replication. Several common fragile sites (CFS) contain A+T-rich regions including perfect [AT/TA] microsatellite repeats that may collapse into hairpins when in single-stranded DNA (ssDNA) form and coincide with chromosomal hotspots for breakage and rearrangements. While many factors contribute to CFS instability, evidence exists for replication stalling within [AT/TA] microsatellite repeats. Currently, it is unknown how stress causes replication stalling within [AT/TA] microsatellite repeats. To investigate this, we utilized FRET to characterize the structures of [AT/TA]25 sequences and also reconstituted lagging strand replication to characterize the progression of pol δ holoenzymes through A+T-rich sequences. The results indicate that [AT/TA]25 sequences adopt hairpins that are unwound by the major ssDNA-binding complex, RPA, and the progression of pol δ holoenzymes through A+T-rich sequences saturated with RPA is dependent on the template sequence and dNTP concentration. Importantly, the effects of RPA on the replication of [AT/TA]25 sequences are dependent on dNTP concentration, whereas the effects of RPA on the replication of A+T-rich, nonstructure-forming sequences are independent of dNTP concentration. Collectively, these results reveal complexities in lagging strand replication and provide novel insights into how [AT/TA] microsatellite repeats contribute to genome instability.
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Affiliation(s)
- Kara G Pytko
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, United States
| | - Rachel L Dannenberg
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, United States
| | - Kristin A Eckert
- Department of Pathology and Laboratory Medicine, The Jake Gittlen Laboratories for Cancer Research, Hershey, PA 17033, United States
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, United States
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5
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Li Y, Zhang Y, Shah SB, Chang CY, Wang H, Wu X. MutSβ protects common fragile sites by facilitating homology-directed repair at DNA double-strand breaks with secondary structures. Nucleic Acids Res 2024; 52:1120-1135. [PMID: 38038265 PMCID: PMC10853791 DOI: 10.1093/nar/gkad1112] [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: 08/10/2023] [Revised: 10/14/2023] [Accepted: 11/07/2023] [Indexed: 12/02/2023] Open
Abstract
Common fragile sites (CFSs) are regions prone to chromosomal rearrangements, thereby contributing to tumorigenesis. Under replication stress (RS), CFSs often harbor under-replicated DNA regions at the onset of mitosis, triggering homology-directed repair known as mitotic DNA synthesis (MiDAS) to complete DNA replication. In this study, we identified an important role of DNA mismatch repair protein MutSβ (MSH2/MSH3) in facilitating MiDAS and maintaining CFS stability. Specifically, we demonstrated that MutSβ is required for the increased mitotic recombination induced by RS or FANCM loss at CFS-derived AT-rich and structure-prone sequences (CFS-ATs). We also found that MSH3 exhibits synthetic lethality with FANCM. Mechanistically, MutSβ is required for homologous recombination (HR) especially when DNA double-strand break (DSB) ends contain secondary structures. We also showed that upon RS, MutSβ is recruited to Flex1, a specific CFS-AT, in a PCNA-dependent but MUS81-independent manner. Furthermore, MutSβ interacts with RAD52 and promotes RAD52 recruitment to Flex1 following MUS81-dependent fork cleavage. RAD52, in turn, recruits XPF/ERCC1 to remove DNA secondary structures at DSB ends, enabling HR/break-induced replication (BIR) at CFS-ATs. We propose that the specific requirement of MutSβ in processing DNA secondary structures at CFS-ATs underlies its crucial role in promoting MiDAS and maintaining CFS integrity.
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Affiliation(s)
- Youhang Li
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Yunkun Zhang
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Sameer Bikram Shah
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Chia-Yu Chang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Hailong Wang
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Xiaohua Wu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
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6
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Irony-Tur Sinai M, Kerem B. Insights into common fragile site instability: DNA replication challenges at DNA repeat sequences. Emerg Top Life Sci 2023; 7:277-287. [PMID: 37876349 PMCID: PMC10754330 DOI: 10.1042/etls20230023] [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: 08/02/2023] [Revised: 10/08/2023] [Accepted: 10/12/2023] [Indexed: 10/26/2023]
Abstract
Common fragile sites (CFS) are specific genomic regions prone to chromosomal instability under conditions of DNA replication stress. CFSs manifest as breaks, gaps, and constrictions on metaphase chromosomes under mild replication stress. These replication-sensitive CFS regions are preferentially unstable during cancer development, as reflected by their association with copy number variants (CNVs) frequently arise in most tumor types. Over the years, it became clear that a combination of different characteristics underlies the enhanced sensitivity of CFSs to replication stress. As of today, there is a strong evidence that the core fragility regions along CFSs overlap with actively transcribed large genes with delayed replication timing upon replication stress. Recently, the mechanistic basis for CFS instability was further extended to regions which span topologically associated domain (TAD) boundaries, generating a fragility signature composed of replication, transcription and genome organization. The presence of difficult-to-replicate AT-rich repeats was one of the early features suggested to characterize a subgroup of CFSs. These long stretches of AT-dinucleotide have the potential to fold into stable secondary structures which may impede replication fork progression, leaving the region under-replicated. Here, we focus on the molecular mechanisms underlying repeat instability at CFSs and on the proteins involved in the resolution of secondary structure impediments arising along repetitive sequence elements which are essential for the maintenance of genome stability.
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Affiliation(s)
- Michal Irony-Tur Sinai
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem, Israel
| | - Batsheva Kerem
- Department of Genetics, The Life Sciences Institute, The Hebrew University, Jerusalem, Israel
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7
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Abstract
Transcription and replication both require large macromolecular complexes to act on a DNA template, yet these machineries cannot simultaneously act on the same DNA sequence. Conflicts between the replication and transcription machineries (transcription-replication conflicts, or TRCs) are widespread in both prokaryotes and eukaryotes and have the capacity to both cause DNA damage and compromise complete, faithful replication of the genome. This review will highlight recent studies investigating the genomic locations of TRCs and the mechanisms by which they may be prevented, mitigated, or resolved. We address work from both model organisms and mammalian systems but predominantly focus on multicellular eukaryotes owing to the additional complexities inherent in the coordination of replication and transcription in the context of cell type-specific gene expression and higher-order chromatin organization.
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Affiliation(s)
- Liana Goehring
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA;
| | - Tony T Huang
- Department of Biochemistry & Molecular Pharmacology, New York University School of Medicine, New York, NY, USA;
| | - Duncan J Smith
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, USA;
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8
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Pytko KG, Dannenberg RL, Eckert KA, Hedglin M. Replication of [AT/TA] 25 microsatellite sequences by human DNA polymerase δ holoenzymes is dependent on dNTP and RPA levels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.07.566133. [PMID: 37986888 PMCID: PMC10659299 DOI: 10.1101/2023.11.07.566133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Difficult-to-Replicate Sequences (DiToRS) are natural impediments in the human genome that inhibit DNA replication under endogenous replication. Some of the most widely-studied DiToRS are A+T-rich, high "flexibility regions," including long stretches of perfect [AT/TA] microsatellite repeats that have the potential to collapse into hairpin structures when in single-stranded DNA (ssDNA) form and are sites of recurrent structural variation and double-stranded DNA (dsDNA) breaks. Currently, it is unclear how these flexibility regions impact DNA replication, greatly limiting our fundamental understanding of human genome stability. To investigate replication through flexibility regions, we utilized FRET to characterize the effects of the major ssDNA-binding complex, RPA, on the structure of perfect [AT/TA]25 microsatellite repeats and also re-constituted human lagging strand replication to quantitatively characterize initial encounters of pol δ holoenzymes with A+T-rich DNA template sequences. The results indicate that [AT/TA]25 sequences adopt hairpin structures that are unwound by RPA and pol δ holoenzymes support dNTP incorporation through the [AT/TA]25 sequences as well as an A+T-rich, non-structure forming sequence. Furthermore, the extent of dNTP incorporation is dependent on the sequence of the DNA template and the concentration of dNTPs. Importantly, the effects of RPA on the replication of [AT/TA]25 sequences are dependent on the concentration of dNTPs, whereas the effects of RPA on the replication of an A+T-rich, non-structure forming sequence are independent of dNTP concentration. Collectively, these results reveal complexities in lagging strand replication and provide novel insights into how flexibility regions contribute to genome instability.
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Affiliation(s)
- Kara G. Pytko
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Rachel L. Dannenberg
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
| | - Kristin A. Eckert
- Department of Pathology and Laboratory Medicine, The Jake Gittlen Laboratories for Cancer Research, Hershey, PA 17033
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802
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9
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Bhowmick R, Hickson ID, Liu Y. Completing genome replication outside of S phase. Mol Cell 2023; 83:3596-3607. [PMID: 37716351 DOI: 10.1016/j.molcel.2023.08.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 08/03/2023] [Accepted: 08/17/2023] [Indexed: 09/18/2023]
Abstract
Mitotic DNA synthesis (MiDAS) is an unusual form of DNA replication that occurs during mitosis. Initially, MiDAS was characterized as a process associated with intrinsically unstable loci known as common fragile sites that occurs after cells experience DNA replication stress (RS). However, it is now believed to be a more widespread "salvage" mechanism that is called upon to complete the duplication of any under-replicated genomic region. Emerging data suggest that MiDAS is a DNA repair process potentially involving two or more pathways working in parallel or sequentially. In this review, we introduce the causes of RS, regions of the human genome known to be especially vulnerable to RS, and the strategies used to complete DNA replication outside of S phase. Additionally, because MiDAS is a prominent feature of aneuploid cancer cells, we will discuss how targeting MiDAS might potentially lead to improvements in cancer therapy.
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Affiliation(s)
- Rahul Bhowmick
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200 Copenhagen N, Denmark; Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Ian D Hickson
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200 Copenhagen N, Denmark.
| | - Ying Liu
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, Blegdamsvej 3B, 2200 Copenhagen N, Denmark.
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10
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Benitez A, Sebald M, Kanagaraj R, Rodrigo-Brenni MC, Chan YW, Liang CC, West SC. GEN1 promotes common fragile site expression. Cell Rep 2023; 42:112062. [PMID: 36729836 DOI: 10.1016/j.celrep.2023.112062] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 11/01/2022] [Accepted: 01/18/2023] [Indexed: 02/03/2023] Open
Abstract
Our genomes harbor conserved DNA sequences, known as common fragile sites (CFSs), that are difficult to replicate and correspond to regions of genome instability. Following replication stress, CFS loci give rise to breaks or gaps (termed CFS expression) where under-replicated DNA subsequently undergoes mitotic DNA synthesis (MiDAS). We show that loss of the structure-selective endonuclease GEN1 reduces CFS expression, leading to defects in MiDAS, ultrafine anaphase bridge formation, and DNA damage in the ensuing cell cycle due to aberrant chromosome segregation. GEN1 knockout cells also exhibit an elevated frequency of bichromatid constrictions consistent with the presence of unresolved regions of under-replicated DNA. Previously, the role of GEN1 was thought to be restricted to the nucleolytic resolution of recombination intermediates. However, its ability to cleave under-replicated DNA at CFS loci indicates that GEN1 plays a dual role resolving both DNA replication and recombination intermediates before chromosome segregation.
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Affiliation(s)
- Anaid Benitez
- The Francis Crick Institute, DNA Recombination and Repair Laboratory, 1 Midland Road, London NW1 1AT, UK
| | - Marie Sebald
- The Francis Crick Institute, DNA Recombination and Repair Laboratory, 1 Midland Road, London NW1 1AT, UK
| | - Radhakrishnan Kanagaraj
- The Francis Crick Institute, DNA Recombination and Repair Laboratory, 1 Midland Road, London NW1 1AT, UK
| | - Monica C Rodrigo-Brenni
- The Francis Crick Institute, DNA Recombination and Repair Laboratory, 1 Midland Road, London NW1 1AT, UK
| | - Ying Wai Chan
- The Francis Crick Institute, DNA Recombination and Repair Laboratory, 1 Midland Road, London NW1 1AT, UK
| | - Chih-Chao Liang
- The Francis Crick Institute, DNA Recombination and Repair Laboratory, 1 Midland Road, London NW1 1AT, UK
| | - Stephen C West
- The Francis Crick Institute, DNA Recombination and Repair Laboratory, 1 Midland Road, London NW1 1AT, UK.
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11
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Liao YY, Cao WM. The progress in our understanding of CIN in breast cancer research. Front Oncol 2023; 13:1067735. [PMID: 36874134 PMCID: PMC9978327 DOI: 10.3389/fonc.2023.1067735] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 01/02/2023] [Indexed: 02/18/2023] Open
Abstract
Chromosomal instability (CIN) is an important marker of cancer, which is closely related to tumorigenesis, disease progression, treatment efficacy, and patient prognosis. However, due to the limitations of the currently available detection methods, its exact clinical significance remains unknown. Previous studies have demonstrated that 89% of invasive breast cancer cases possess CIN, suggesting that it has potential application in breast cancer diagnosis and treatment. In this review, we describe the two main types of CIN and discuss the associated detection methods. Subsequently, we highlight the impact of CIN in breast cancer development and progression and describe how it can influence treatment and prognosis. The goal of this review is to provide a reference on its mechanism for researchers and clinicians.
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Affiliation(s)
- Yu-Yang Liao
- Wenzhou Medical University, Wenzhou, China
- Department of Breast Medical Oncology, Zhejiang Cancer Hospital, Hangzhou, China
| | - Wen-Ming Cao
- Department of Breast Medical Oncology, Zhejiang Cancer Hospital, Hangzhou, China
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12
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Gibson WS, Rodriguez OL, Shields K, Silver CA, Dorgham A, Emery M, Deikus G, Sebra R, Eichler EE, Bashir A, Smith ML, Watson CT. Characterization of the immunoglobulin lambda chain locus from diverse populations reveals extensive genetic variation. Genes Immun 2023; 24:21-31. [PMID: 36539592 PMCID: PMC10041605 DOI: 10.1038/s41435-022-00188-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/07/2022] [Accepted: 10/13/2022] [Indexed: 12/24/2022]
Abstract
Immunoglobulins (IGs), crucial components of the adaptive immune system, are encoded by three genomic loci. However, the complexity of the IG loci severely limits the effective use of short read sequencing, limiting our knowledge of population diversity in these loci. We leveraged existing long read whole-genome sequencing (WGS) data, fosmid technology, and IG targeted single-molecule, real-time (SMRT) long-read sequencing (IG-Cap) to create haplotype-resolved assemblies of the IG Lambda (IGL) locus from 6 ethnically diverse individuals. In addition, we generated 10 diploid assemblies of IGL from a diverse cohort of individuals utilizing IG-Cap. From these 16 individuals, we identified significant allelic diversity, including 36 novel IGLV alleles. In addition, we observed highly elevated single nucleotide variation (SNV) in IGLV genes relative to IGL intergenic and genomic background SNV density. By comparing SNV calls between our high quality assemblies and existing short read datasets from the same individuals, we show a high propensity for false-positives in the short read datasets. Finally, for the first time, we nucleotide-resolved common 5-10 Kb duplications in the IGLC region that contain functional IGLJ and IGLC genes. Together these data represent a significant advancement in our understanding of genetic variation and population diversity in the IGL locus.
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Affiliation(s)
- William S Gibson
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY, USA
| | - Oscar L Rodriguez
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY, USA
| | - Kaitlyn Shields
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY, USA
| | - Catherine A Silver
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY, USA
| | - Abdullah Dorgham
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY, USA
| | - Matthew Emery
- Icahn Institute of Genomics Technology and Data Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Gintaras Deikus
- Icahn Institute of Genomics Technology and Data Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Robert Sebra
- Icahn Institute of Genomics Technology and Data Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Sema4, Stamford, CT, USA
| | - Evan E Eichler
- Department of Genome Sciences, University of Washington School of Medicine, Seattle, WA, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
| | - Ali Bashir
- Google Accelerated Science Team, Google Inc, Mountain View, CA, USA
| | - Melissa L Smith
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY, USA.
| | - Corey T Watson
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY, USA.
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13
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Mirceta M, Shum N, Schmidt MHM, Pearson CE. Fragile sites, chromosomal lesions, tandem repeats, and disease. Front Genet 2022; 13:985975. [PMID: 36468036 PMCID: PMC9714581 DOI: 10.3389/fgene.2022.985975] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 09/02/2022] [Indexed: 09/16/2023] Open
Abstract
Expanded tandem repeat DNAs are associated with various unusual chromosomal lesions, despiralizations, multi-branched inter-chromosomal associations, and fragile sites. Fragile sites cytogenetically manifest as localized gaps or discontinuities in chromosome structure and are an important genetic, biological, and health-related phenomena. Common fragile sites (∼230), present in most individuals, are induced by aphidicolin and can be associated with cancer; of the 27 molecularly-mapped common sites, none are associated with a particular DNA sequence motif. Rare fragile sites ( ≳ 40 known), ≤ 5% of the population (may be as few as a single individual), can be associated with neurodevelopmental disease. All 10 molecularly-mapped folate-sensitive fragile sites, the largest category of rare fragile sites, are caused by gene-specific CGG/CCG tandem repeat expansions that are aberrantly CpG methylated and include FRAXA, FRAXE, FRAXF, FRA2A, FRA7A, FRA10A, FRA11A, FRA11B, FRA12A, and FRA16A. The minisatellite-associated rare fragile sites, FRA10B, FRA16B, can be induced by AT-rich DNA-ligands or nucleotide analogs. Despiralized lesions and multi-branched inter-chromosomal associations at the heterochromatic satellite repeats of chromosomes 1, 9, 16 are inducible by de-methylating agents like 5-azadeoxycytidine and can spontaneously arise in patients with ICF syndrome (Immunodeficiency Centromeric instability and Facial anomalies) with mutations in genes regulating DNA methylation. ICF individuals have hypomethylated satellites I-III, alpha-satellites, and subtelomeric repeats. Ribosomal repeats and subtelomeric D4Z4 megasatellites/macrosatellites, are associated with chromosome location, fragility, and disease. Telomere repeats can also assume fragile sites. Dietary deficiencies of folate or vitamin B12, or drug insults are associated with megaloblastic and/or pernicious anemia, that display chromosomes with fragile sites. The recent discovery of many new tandem repeat expansion loci, with varied repeat motifs, where motif lengths can range from mono-nucleotides to megabase units, could be the molecular cause of new fragile sites, or other chromosomal lesions. This review focuses on repeat-associated fragility, covering their induction, cytogenetics, epigenetics, cell type specificity, genetic instability (repeat instability, micronuclei, deletions/rearrangements, and sister chromatid exchange), unusual heritability, disease association, and penetrance. Understanding tandem repeat-associated chromosomal fragile sites provides insight to chromosome structure, genome packaging, genetic instability, and disease.
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Affiliation(s)
- Mila Mirceta
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Natalie Shum
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Monika H. M. Schmidt
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Christopher E. Pearson
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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14
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Ji F, Zhu X, Liao H, Ouyang L, Huang Y, Syeda MZ, Ying S. New Era of Mapping and Understanding Common Fragile Sites: An Updated Review on Origin of Chromosome Fragility. Front Genet 2022; 13:906957. [PMID: 35669181 PMCID: PMC9164283 DOI: 10.3389/fgene.2022.906957] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 04/25/2022] [Indexed: 11/13/2022] Open
Abstract
Common fragile sites (CFSs) are specific genomic loci prone to forming gaps or breakages upon replication perturbation, which correlate well with chromosomal rearrangement and copy number variation. CFSs have been actively studied due to their important pathophysiological relevance in different diseases such as cancer and neurological disorders. The genetic locations and sequences of CFSs are crucial to understanding the origin of such unstable sites, which require reliable mapping and characterizing approaches. In this review, we will inspect the evolving techniques for CFSs mapping, especially genome-wide mapping and sequencing of CFSs based on current knowledge of CFSs. We will also revisit the well-established hypotheses on the origin of CFSs fragility, incorporating novel findings from the comprehensive analysis of finely mapped CFSs regarding their locations, sequences, and replication/transcription, etc. This review will present the most up-to-date picture of CFSs and, potentially, a new framework for future research of CFSs.
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Affiliation(s)
- Fang Ji
- International Institutes of Medicine, The Fourth Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, China.,Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Xinli Zhu
- Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Hongwei Liao
- International Institutes of Medicine, The Fourth Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, China.,Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Liujian Ouyang
- Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Yingfei Huang
- Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Madiha Zahra Syeda
- Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
| | - Songmin Ying
- International Institutes of Medicine, The Fourth Affiliated Hospital of Zhejiang University School of Medicine, Yiwu, China.,Department of Pharmacology and Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Key Laboratory of Respiratory Disease of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, China
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15
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Lokanga RA, Kumari D, Usdin K. Common Threads: Aphidicolin-Inducible and Folate-Sensitive Fragile Sites in the Human Genome. Front Genet 2021; 12:708860. [PMID: 34567068 PMCID: PMC8456018 DOI: 10.3389/fgene.2021.708860] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/28/2021] [Indexed: 11/13/2022] Open
Abstract
The human genome has many chromosomal regions that are fragile, demonstrating chromatin breaks, gaps, or constrictions on exposure to replication stress. Common fragile sites (CFSs) are found widely distributed in the population, with the largest subset of these sites being induced by aphidicolin (APH). Other fragile sites are only found in a subset of the population. One group of these so-called rare fragile sites (RFSs) is induced by folate stress. APH-inducible CFSs are generally located in large transcriptionally active genes that are A + T rich and often enriched for tracts of AT-dinucleotide repeats. In contrast, all the folate-sensitive sites mapped to date consist of transcriptionally silenced CGG microsatellites. Thus, all the folate-sensitive fragile sites may have a very similar molecular basis that differs in key ways from that of the APH CFSs. The folate-sensitive FSs include FRAXA that is associated with Fragile X syndrome (FXS), the most common heritable form of intellectual disability. Both CFSs and RFSs can cause chromosomal abnormalities. Recent work suggests that both APH-inducible fragile sites and FRAXA undergo Mitotic DNA synthesis (MiDAS) when exposed to APH or folate stress, respectively. Interestingly, blocking MiDAS in both cases prevents chromosome fragility but increases the risk of chromosome mis-segregation. MiDAS of both APH-inducible and FRAXA involves conservative DNA replication and POLD3, an accessory subunit of the replicative polymerase Pol δ that is essential for break-induced replication (BIR). Thus, MiDAS is thought to proceed via some form of BIR-like process. This review will discuss the recent work that highlights the similarities and differences between these two groups of fragile sites and the growing evidence for the presence of many more novel fragile sites in the human genome.
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Affiliation(s)
| | - Daman Kumari
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Karen Usdin
- Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
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16
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Dong WG, Dong Y, Guo XG, Shao R. Frequent tRNA gene translocation towards the boundaries with control regions contributes to the highly dynamic mitochondrial genome organization of the parasitic lice of mammals. BMC Genomics 2021; 22:598. [PMID: 34362306 PMCID: PMC8344215 DOI: 10.1186/s12864-021-07859-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 06/29/2021] [Indexed: 11/22/2022] Open
Abstract
Background The typical single-chromosome mitochondrial (mt) genome of animals has fragmented into multiple minichromosomes in the lineage Mitodivisia, which contains most of the parasitic lice of eutherian mammals. These parasitic lice differ from each other even among congeneric species in mt karyotype, i.e. the number of minichromosomes, and the gene content and gene order in each minichromosome, which is in stark contrast to the extremely conserved single-chromosome mt genomes across most animal lineages. How fragmented mt genomes evolved is still poorly understood. We use Polyplax sucking lice as a model to investigate how tRNA gene translocation shapes the dynamic mt karyotypes. Results We sequenced the full mt genome of the Asian grey shrew louse, Polyplax reclinata. We then inferred the ancestral mt karyotype for Polyplax lice and compared it with the mt karyotypes of the three Polyplax species sequenced to date. We found that tRNA genes were entirely responsible for mt karyotype variation among these three species of Polyplax lice. Furthermore, tRNA gene translocation observed in Polyplax lice was only between different types of minichromosomes and towards the boundaries with the control region. A similar pattern of tRNA gene translocation can also been seen in other sucking lice with fragmented mt genomes. Conclusions We conclude that inter-minichromosomal tRNA gene translocation orientated towards the boundaries with the control region is a major contributing factor to the highly dynamic mitochondrial genome organization in the parasitic lice of mammals. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07859-w.
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Affiliation(s)
- Wen-Ge Dong
- Institute of Pathogens and Vectors, Key Laboratory for Preventing and Controlling Plague in Yunnan Province, Dali University, 671000, Dali, China.
| | - Yalun Dong
- GeneCology Research Centre, University of the Sunshine Coast, Maroochydore, Queensland, Australia.,School of Science, Technology and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia
| | - Xian-Guo Guo
- Institute of Pathogens and Vectors, Key Laboratory for Preventing and Controlling Plague in Yunnan Province, Dali University, 671000, Dali, China
| | - Renfu Shao
- GeneCology Research Centre, University of the Sunshine Coast, Maroochydore, Queensland, Australia. .,School of Science, Technology and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, Australia.
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17
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Siri SO, Martino J, Gottifredi V. Structural Chromosome Instability: Types, Origins, Consequences, and Therapeutic Opportunities. Cancers (Basel) 2021; 13:3056. [PMID: 34205328 PMCID: PMC8234978 DOI: 10.3390/cancers13123056] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 01/04/2023] Open
Abstract
Chromosomal instability (CIN) refers to an increased rate of acquisition of numerical and structural changes in chromosomes and is considered an enabling characteristic of tumors. Given its role as a facilitator of genomic changes, CIN is increasingly being considered as a possible therapeutic target, raising the question of which variables may convert CIN into an ally instead of an enemy during cancer treatment. This review discusses the origins of structural chromosome abnormalities and the cellular mechanisms that prevent and resolve them, as well as how different CIN phenotypes relate to each other. We discuss the possible fates of cells containing structural CIN, focusing on how a few cell duplication cycles suffice to induce profound CIN-mediated genome alterations. Because such alterations can promote tumor adaptation to treatment, we discuss currently proposed strategies to either avoid CIN or enhance CIN to a level that is no longer compatible with cell survival.
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Affiliation(s)
- Sebastián Omar Siri
- Cell Cycle and Genome Stability Laboratory, Fundación Instituto Leloir, C1405 BWE Buenos Aires, Argentina;
- Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1405 BWE Buenos Aires, Argentina
| | - Julieta Martino
- Cell Cycle and Genome Stability Laboratory, Fundación Instituto Leloir, C1405 BWE Buenos Aires, Argentina;
| | - Vanesa Gottifredi
- Cell Cycle and Genome Stability Laboratory, Fundación Instituto Leloir, C1405 BWE Buenos Aires, Argentina;
- Instituto de Investigaciones Bioquímicas de Buenos Aires (IIBBA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1405 BWE Buenos Aires, Argentina
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18
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Abstract
Unlike bacteria, mammalian cells need to complete DNA replication before segregating their chromosomes for the maintenance of genome integrity. Thus, cells have evolved efficient pathways to restore stalled and/or collapsed replication forks during S-phase, and when necessary, also to delay cell cycle progression to ensure replication completion. However, strong evidence shows that cells can proceed to mitosis with incompletely replicated DNA when under mild replication stress (RS) conditions. Consequently, the incompletely replicated genomic gaps form, predominantly at common fragile site regions, where the converging fork-like DNA structures accumulate. These branched structures pose a severe threat to the faithful disjunction of chromosomes as they physically interlink the partially duplicated sister chromatids. In this review, we provide an overview discussing how cells respond and deal with the under-replicated DNA structures that escape from the S/G2 surveillance system. We also focus on recent research of a mitotic break-induced replication pathway (also known as mitotic DNA repair synthesis), which has been proposed to operate during prophase in an attempt to finish DNA synthesis at the under-replicated genomic regions. Finally, we discuss recent data on how mild RS may cause chromosome instability and mutations that accelerate cancer genome evolution.
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Affiliation(s)
- Camelia Mocanu
- Chromosome Dynamics and Stability Group, Genome Damage and Stability Centre, University of Sussex, Brighton BN1 7BG, UK
| | - Kok-Lung Chan
- Chromosome Dynamics and Stability Group, Genome Damage and Stability Centre, University of Sussex, Brighton BN1 7BG, UK
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19
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Replication Stress, Genomic Instability, and Replication Timing: A Complex Relationship. Int J Mol Sci 2021; 22:ijms22094764. [PMID: 33946274 PMCID: PMC8125245 DOI: 10.3390/ijms22094764] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/26/2021] [Accepted: 04/28/2021] [Indexed: 12/29/2022] Open
Abstract
The replication-timing program constitutes a key element of the organization and coordination of numerous nuclear processes in eukaryotes. This program is established at a crucial moment in the cell cycle and occurs simultaneously with the organization of the genome, thus indicating the vital significance of this process. With recent technological achievements of high-throughput approaches, a very strong link has been confirmed between replication timing, transcriptional activity, the epigenetic and mutational landscape, and the 3D organization of the genome. There is also a clear relationship between replication stress, replication timing, and genomic instability, but the extent to which they are mutually linked to each other is unclear. Recent evidence has shown that replication timing is affected in cancer cells, although the cause and consequence of this effect remain unknown. However, in-depth studies remain to be performed to characterize the molecular mechanisms of replication-timing regulation and clearly identify different cis- and trans-acting factors. The results of these studies will potentially facilitate the discovery of new therapeutic pathways, particularly for personalized medicine, or new biomarkers. This review focuses on the complex relationship between replication timing, replication stress, and genomic instability.
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20
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Li D, Pan S, Zhang H, Fu Y, Peng Z, Zhang L, Peng S, Xu F, Huang H, Shi R, Zheng H, Peng Y, Tan Z. A comprehensive microsatellite landscape of human Y-DNA at kilobase resolution. BMC Genomics 2021; 22:76. [PMID: 33482734 PMCID: PMC7821415 DOI: 10.1186/s12864-021-07389-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 01/13/2021] [Indexed: 12/12/2022] Open
Abstract
Background Though interest in human simple sequence repeats (SSRs) is increasing, little is known about the exact distributional features of numerous SSRs in human Y-DNA at chromosomal level. Herein, totally 540 maps were established, which could clearly display SSR landscape in every bin of 1 k base pairs (Kbp) along the sequenced part of human reference Y-DNA (NC_000024.10), by our developed differential method for improving the existing method to reveal SSR distributional characteristics in large genomic sequences. Results The maps show that SSRs accumulate significantly with forming density peaks in at least 2040 bins of 1 Kbp, which involve different coding, noncoding and intergenic regions of the Y-DNA, and 10 especially high density peaks were reported to associate with biological significances, suggesting that the other hundreds of especially high density peaks might also be biologically significant and worth further analyzing. In contrast, the maps also show that SSRs are extremely sparse in at least 207 bins of 1 Kbp, including many noncoding and intergenic regions of the Y-DNA, which is inconsistent with the widely accepted view that SSRs are mostly rich in these regions, and these sparse distributions are possibly due to powerfully regional selection. Additionally, many regions harbor SSR clusters with same or similar motif in the Y-DNA. Conclusions These 540 maps may provide the important information of clearly position-related SSR distributional features along the human reference Y-DNA for better understanding the genome structures of the Y-DNA. This study may contribute to further exploring the biological significance and distribution law of the huge numbers of SSRs in human Y-DNA. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07389-5.
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Affiliation(s)
- Douyue Li
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Saichao Pan
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Hongxi Zhang
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Yongzhuo Fu
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Zhuli Peng
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Liang Zhang
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Shan Peng
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Fei Xu
- Department of Mathematics, Wilfrid Laurier University, Waterloo, Ontario, N2L 3C5, Canada
| | - Hanrou Huang
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Ruixue Shi
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Heping Zheng
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Yousong Peng
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Zhongyang Tan
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China.
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21
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Li S, Wang H, Jehi S, Li J, Liu S, Wang Z, Truong L, Chiba T, Wang Z, Wu X. PIF1 helicase promotes break-induced replication in mammalian cells. EMBO J 2021; 40:e104509. [PMID: 33470420 PMCID: PMC8047440 DOI: 10.15252/embj.2020104509] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 12/01/2020] [Accepted: 12/10/2020] [Indexed: 12/20/2022] Open
Abstract
Break‐induced replication (BIR) is a specialized homologous‐recombination pathway for DNA double‐strand break (DSB) repair, which often induces genome instability. In this study, we establish EGFP‐based recombination reporters to systematically study BIR in mammalian cells and demonstrate an important role of human PIF1 helicase in promoting BIR. We show that at endonuclease cleavage sites, PIF1‐dependent BIR is used for homology‐initiated recombination requiring long track DNA synthesis, but not short track gene conversion (STGC). We also show that structure formation‐prone AT‐rich DNA sequences derived from common fragile sites (CFS‐ATs) induce BIR upon replication stress and oncogenic stress, and PCNA‐dependent loading of PIF1 onto collapsed/broken forks is critical for BIR activation. At broken replication forks, even STGC‐mediated repair of double‐ended DSBs depends on POLD3 and PIF1, revealing an unexpected mechanism of BIR activation upon replication stress that differs from the conventional BIR activation model requiring DSB end sensing at endonuclease‐generated breaks. Furthermore, loss of PIF1 is synthetically lethal with loss of FANCM, which is involved in protecting CFS‐ATs. The breast cancer‐associated PIF1 mutant L319P is defective in BIR, suggesting a direct link of BIR to oncogenic processes.
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Affiliation(s)
- Shibo Li
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Hailong Wang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Sanaa Jehi
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Jun Li
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Shuo Liu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Zi Wang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA.,Biomedical Gerontology Laboratory, Department of Health Science and Social Welfare, School of Human Sciences, Waseda University, Tokorozawa, Japan
| | - Lan Truong
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Takuya Chiba
- Biomedical Gerontology Laboratory, Department of Health Science and Social Welfare, School of Human Sciences, Waseda University, Tokorozawa, Japan
| | - Zefeng Wang
- CAS Key Laboratory of Computational Biology, University of Chinese Academy of Sciences, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xiaohua Wu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
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22
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Brown RE, Freudenreich CH. Structure-forming repeats and their impact on genome stability. Curr Opin Genet Dev 2020; 67:41-51. [PMID: 33279816 DOI: 10.1016/j.gde.2020.10.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/22/2020] [Accepted: 10/24/2020] [Indexed: 12/12/2022]
Abstract
Repetitive sequences throughout the genome are a major source of endogenous DNA damage, due to the propensity of many of them to form alternative non-B DNA structures that can interfere with replication, transcription, and DNA repair. These repetitive sequences are prone to breakage (fragility) and instability (changes in repeat number). Repeat fragility and expansions are linked to several diseases, including many cancers and neurodegenerative diseases, hence the importance of understanding the mechanisms that cause genome instability and contribute to these diseases. This review focuses on recent findings of mechanisms causing repeat fragility and instability, new associations between repeat expansions and genetic diseases, and potential therapeutic options to target repeat expansions.
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Affiliation(s)
- Rebecca E Brown
- Program in Genetics, Tufts University Graduate School of Biomedical Sciences, Boston, MA 02111, USA
| | - Catherine H Freudenreich
- Department of Biology, Tufts University, Medford, MA 02155, USA; Program in Genetics, Tufts University Graduate School of Biomedical Sciences, Boston, MA 02111, USA.
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23
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Macheret M, Bhowmick R, Sobkowiak K, Padayachy L, Mailler J, Hickson ID, Halazonetis TD. High-resolution mapping of mitotic DNA synthesis regions and common fragile sites in the human genome through direct sequencing. Cell Res 2020; 30:997-1008. [PMID: 32561860 PMCID: PMC7784693 DOI: 10.1038/s41422-020-0358-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 05/31/2020] [Indexed: 12/22/2022] Open
Abstract
DNA replication stress, a feature of human cancers, often leads to instability at specific genomic loci, such as the common fragile sites (CFSs). Cells experiencing DNA replication stress may also exhibit mitotic DNA synthesis (MiDAS). To understand the physiological function of MiDAS and its relationship to CFSs, we mapped, at high resolution, the genomic sites of MiDAS in cells treated with the DNA polymerase inhibitor aphidicolin. Sites of MiDAS were evident as well-defined peaks that were largely conserved between cell lines and encompassed all known CFSs. The MiDAS peaks mapped within large, transcribed, origin-poor genomic regions. In cells that had been treated with aphidicolin, these regions remained unreplicated even in late S phase; MiDAS then served to complete their replication after the cells entered mitosis. Interestingly, leading and lagging strand synthesis were uncoupled in MiDAS, consistent with MiDAS being a form of break-induced replication, a repair mechanism for collapsed DNA replication forks. Our results provide a better understanding of the mechanisms leading to genomic instability at CFSs and in cancer cells.
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Affiliation(s)
- Morgane Macheret
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland
| | - Rahul Bhowmick
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark
| | - Katarzyna Sobkowiak
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland
| | - Laura Padayachy
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland
| | - Jonathan Mailler
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland
| | - Ian D Hickson
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen N, Denmark.
| | - Thanos D Halazonetis
- Department of Molecular Biology, University of Geneva, 1205, Geneva, Switzerland.
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Ma X, Fan J, Wu Y, Zhao S, Zheng X, Sun C, Tan L. Whole-genome de novo assemblies reveal extensive structural variations and dynamic organelle-to-nucleus DNA transfers in African and Asian rice. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 104:596-612. [PMID: 32748498 PMCID: PMC7693357 DOI: 10.1111/tpj.14946] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 07/17/2020] [Accepted: 07/22/2020] [Indexed: 05/05/2023]
Abstract
Asian cultivated rice (Oryza sativa) and African cultivated rice (Oryza glaberrima) originated from the wild rice species Oryza rufipogon and Oryza barthii, respectively. The genomes of both cultivated species have undergone profound changes during domestication. Whole-genome de novo assemblies of O. barthii, O. glaberrima, O. rufipogon and Oryza nivara, produced using PacBio single-molecule real-time (SMRT) and next-generation sequencing (NGS) technologies, showed that Gypsy-like retrotransposons are the major contributors to genome size variation in African and Asian rice. Through the detection of genome-wide structural variations (SVs), we observed that besides 28 shared SV hot spots, another 67 hot spots existed in either the Asian or African rice genomes. Based on gene annotation information of the SVs, we established that organelle-to-nucleus DNA transfers resulted in numerous SVs that participated in the nuclear genome divergence of rice species and subspecies. We detected 52 giant nuclear integrants of organelle DNA (NORGs, defined as >10 kb) in six Oryza AA genomes. In addition, we developed an effective method to genotype giant NORGs, based on genome assembly, and first showed the dynamic change in the distribution of giant NORGs in rice natural population. Interestingly, 16 highly differentiated giant NORGs tended to accumulate in natural populations of Asian rice from higher latitude regions, grown at lower temperatures and light intensities. Our study provides new insight into the genome divergence of African and Asian rice, and establishes that organelle-to-nucleus DNA transfers, as potentially powerful contributors to environmental adaptation during rice evolution, play a major role in producing SVs in rice genomes.
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Affiliation(s)
- Xin Ma
- MOE Key Laboratory of Crop Heterosis and UtilizationNational Center for Evaluation of Agricultural Wild Plants (Rice)Department of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
- State Key Laboratory of AgrobiotechnologyChina Agricultural UniversityBeijing100193China
| | - Jinjian Fan
- MOE Key Laboratory of Crop Heterosis and UtilizationNational Center for Evaluation of Agricultural Wild Plants (Rice)Department of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
- State Key Laboratory of AgrobiotechnologyChina Agricultural UniversityBeijing100193China
| | - Yongzhen Wu
- MOE Key Laboratory of Crop Heterosis and UtilizationNational Center for Evaluation of Agricultural Wild Plants (Rice)Department of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
| | - Shuangshuang Zhao
- MOE Key Laboratory of Crop Heterosis and UtilizationNational Center for Evaluation of Agricultural Wild Plants (Rice)Department of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
| | - Xu Zheng
- MOE Key Laboratory of Crop Heterosis and UtilizationNational Center for Evaluation of Agricultural Wild Plants (Rice)Department of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
| | - Chuanqing Sun
- MOE Key Laboratory of Crop Heterosis and UtilizationNational Center for Evaluation of Agricultural Wild Plants (Rice)Department of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
- State Key Laboratory of Plant Physiology and BiochemistryChina Agricultural UniversityBeijing100193China
| | - Lubin Tan
- MOE Key Laboratory of Crop Heterosis and UtilizationNational Center for Evaluation of Agricultural Wild Plants (Rice)Department of Plant Genetics and BreedingChina Agricultural UniversityBeijing100193China
- State Key Laboratory of AgrobiotechnologyChina Agricultural UniversityBeijing100193China
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25
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Szlachta K, Manukyan A, Raimer HM, Singh S, Salamon A, Guo W, Lobachev KS, Wang YH. Topoisomerase II contributes to DNA secondary structure-mediated double-stranded breaks. Nucleic Acids Res 2020; 48:6654-6671. [PMID: 32501506 PMCID: PMC7337936 DOI: 10.1093/nar/gkaa483] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/20/2020] [Accepted: 06/01/2020] [Indexed: 12/12/2022] Open
Abstract
DNA double-stranded breaks (DSBs) trigger human genome instability, therefore identifying what factors contribute to DSB induction is critical for our understanding of human disease etiology. Using an unbiased, genome-wide approach, we found that genomic regions with the ability to form highly stable DNA secondary structures are enriched for endogenous DSBs in human cells. Human genomic regions predicted to form non-B-form DNA induced gross chromosomal rearrangements in yeast and displayed high indel frequency in human genomes. The extent of instability in both analyses is in concordance with the structure forming ability of these regions. We also observed an enrichment of DNA secondary structure-prone sites overlapping transcription start sites (TSSs) and CCCTC-binding factor (CTCF) binding sites, and uncovered an increase in DSBs at highly stable DNA secondary structure regions, in response to etoposide, an inhibitor of topoisomerase II (TOP2) re-ligation activity. Importantly, we found that TOP2 deficiency in both yeast and human leads to a significant reduction in DSBs at structure-prone loci, and that sites of TOP2 cleavage have a greater ability to form highly stable DNA secondary structures. This study reveals a direct role for TOP2 in generating secondary structure-mediated DNA fragility, advancing our understanding of mechanisms underlying human genome instability.
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Affiliation(s)
- Karol Szlachta
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Arkadi Manukyan
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Heather M Raimer
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Sandeep Singh
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Anita Salamon
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Wenying Guo
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Kirill S Lobachev
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Yuh-Hwa Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
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26
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Zhang H, Li D, Zhao X, Pan S, Wu X, Peng S, Huang H, Shi R, Tan Z. Relatively semi-conservative replication and a folded slippage model for short tandem repeats. BMC Genomics 2020; 21:563. [PMID: 32807079 PMCID: PMC7430839 DOI: 10.1186/s12864-020-06949-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 07/27/2020] [Indexed: 12/11/2022] Open
Abstract
Background The ubiquitous presence of short tandem repeats (STRs) in virtually all genomes implicates their functional relevance, while a widely-accepted definition of STR is yet to be established. Previous studies majorly focus on relatively longer STRs, while shorter repeats were generally excluded. Herein, we have adopted a more generous criteria to define shorter repeats, which has led to the definition of a much larger number of STRs that lack prior analysis. Using this definition, we analyzed the short repeats in 55 randomly selected segments in 55 randomly selected genomic sequences from a fairly wide range of species covering animals, plants, fungi, protozoa, bacteria, archaea and viruses. Results Our analysis reveals a high percentage of short repeats in all 55 randomly selected segments, indicating that the universal presence of high-content short repeats could be a common characteristic of genomes across all biological kingdoms. Therefore, it is reasonable to assume a mechanism for continuous production of repeats that can make the replicating process relatively semi-conservative. We have proposed a folded replication slippage model that considers the geometric space of nucleotides and hydrogen bond stability to explain the mechanism more explicitly, with improving the existing straight-line slippage model. The folded slippage model can explain the expansion and contraction of mono- to hexa- nucleotide repeats with proper folding angles. Analysis of external forces in the folding template strands also suggests that expansion exists more commonly than contraction in the short tandem repeats. Conclusion The folded replication slippage model provides a reasonable explanation for the continuous occurrences of simple sequence repeats in genomes. This model also contributes to the explanation of STR-to-genome evolution and is an alternative model that complements semi-conservative replication.
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Affiliation(s)
- Hongxi Zhang
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Douyue Li
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Xiangyan Zhao
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Saichao Pan
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Xiaolong Wu
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Shan Peng
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Hanrou Huang
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Ruixue Shi
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China
| | - Zhongyang Tan
- Bioinformatics Center, College of Biology, Hunan University, Changsha, 410082, China.
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27
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Ji F, Liao H, Pan S, Ouyang L, Jia F, Fu Z, Zhang F, Geng X, Wang X, Li T, Liu S, Syeda MZ, Chen H, Li W, Chen Z, Shen H, Ying S. Genome-wide high-resolution mapping of mitotic DNA synthesis sites and common fragile sites by direct sequencing. Cell Res 2020; 30:1009-1023. [PMID: 32561861 DOI: 10.1038/s41422-020-0357-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 05/31/2020] [Indexed: 01/13/2023] Open
Abstract
Common fragile sites (CFSs) are genomic loci prone to the formation of breaks or gaps on metaphase chromosomes. They are hotspots for chromosome rearrangements and structural variations, which have been extensively implicated in carcinogenesis, aging, and other pathological processes. Although many CFSs were identified decades ago, a consensus is still lacking for why they are particularly unstable and sensitive to replication perturbations. This is in part due to the lack of high-resolution mapping data for the vast majority of the CFSs, which has hindered mechanistic interrogations. Here, we seek to map human CFSs with high resolution on a genome-wide scale by sequencing the sites of mitotic DNA synthesis (MiDASeq) that are specific for CFSs. We generated a nucleotide-resolution atlas of MiDAS sites (MDSs) that covered most of the known CFSs, and comprehensively analyzed their sequence characteristics and genomic features. Our data on MDSs tallied well with long-standing hypotheses to explain CFS fragility while highlighting the contributions of late replication timing and large transcription units. Notably, the MDSs also encompassed most of the recurrent double-strand break clusters previously identified in mouse neural stem/progenitor cells, thus bridging evolutionarily conserved break points across species. Moreover, MiDAseq provides an important resource that can stimulate future research on CFSs to further unravel the mechanisms and biological relevance underlying these labile genomic regions.
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Affiliation(s)
- Fang Ji
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China
| | - Hongwei Liao
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China
| | - Sheng Pan
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China.,Chu Kochen Honors College of Zhejiang University, Hangzhou, Zhejiang, China
| | - Liujian Ouyang
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China.,Chu Kochen Honors College of Zhejiang University, Hangzhou, Zhejiang, China
| | - Fang Jia
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China.,Chu Kochen Honors College of Zhejiang University, Hangzhou, Zhejiang, China
| | - Zaiyang Fu
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China.,Chu Kochen Honors College of Zhejiang University, Hangzhou, Zhejiang, China
| | - Fengjiao Zhang
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China
| | - Xinwei Geng
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China
| | - Xinming Wang
- School of Life Sciences, Peking University, Beijing, 100871, China
| | - Tingting Li
- State Key Laboratory of Proteomics, National Center of Biomedical Analysis, Institute of Basic Medical Sciences, Beijing, 100850, China
| | - Shuangying Liu
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China.,Chu Kochen Honors College of Zhejiang University, Hangzhou, Zhejiang, China
| | - Madiha Zahra Syeda
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China
| | - Haixia Chen
- Key Laboratory of Respiratory Disease of Zhejiang Province, Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310009, China
| | - Wen Li
- Key Laboratory of Respiratory Disease of Zhejiang Province, Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310009, China
| | - Zhihua Chen
- Key Laboratory of Respiratory Disease of Zhejiang Province, Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310009, China
| | - Huahao Shen
- Key Laboratory of Respiratory Disease of Zhejiang Province, Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310009, China. .,State Key Laboratory of Respiratory Diseases, Guangzhou, Guangdong, 510120, China.
| | - Songmin Ying
- Department of Pharmacology & Department of Respiratory and Critical Care Medicine of the Second Affiliated Hospital, Zhejiang University School of Medicine, Key Laboratory of Respiratory Disease of Zhejiang Province, Hangzhou, Zhejiang, 310009, China.
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28
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Abstract
Common fragile sites (CFSs) are large chromosomal regions that exhibit breakage on metaphase chromosomes upon replication stress. They become preferentially unstable at the early stage of cancer development and are hotspots for chromosomal rearrangements in cancers. Increasing evidence has highlighted the complexity underlying the instability of CFSs, and a combination of multiple mechanisms is believed to cause CFS fragility. We will review recent advancements in our understanding of the molecular mechanisms underlying the maintenance of CFS stability and the relevance of CFSs to cancer-associated genome instability. We will emphasize the contribution of the structure-prone AT-rich sequences to CFS instability, which is in line with the recent genome-wide study showing that structure-forming repeat sequences are principal sites of replication stress.
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Affiliation(s)
- Shibo Li
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, San Diego, CA 92037 USA
| | - Xiaohua Wu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, San Diego, CA 92037 USA
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29
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Transcription-mediated organization of the replication initiation program across large genes sets common fragile sites genome-wide. Nat Commun 2019; 10:5693. [PMID: 31836700 PMCID: PMC6911102 DOI: 10.1038/s41467-019-13674-5] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 11/15/2019] [Indexed: 12/29/2022] Open
Abstract
Common fragile sites (CFSs) are chromosome regions prone to breakage upon replication stress known to drive chromosome rearrangements during oncogenesis. Most CFSs nest in large expressed genes, suggesting that transcription could elicit their instability; however, the underlying mechanisms remain elusive. Genome-wide replication timing analyses here show that stress-induced delayed/under-replication is the hallmark of CFSs. Extensive genome-wide analyses of nascent transcripts, replication origin positioning and fork directionality reveal that 80% of CFSs nest in large transcribed domains poor in initiation events, replicated by long-travelling forks. Forks that travel long in late S phase explains CFS replication features, whereas formation of sequence-dependent fork barriers or head-on transcription–replication conflicts do not. We further show that transcription inhibition during S phase, which suppresses transcription–replication encounters and prevents origin resetting, could not rescue CFS stability. Altogether, our results show that transcription-dependent suppression of initiation events delays replication of large gene bodies, committing them to instability. Common Fragile Sites (CFSs) are chromosome regions prone to breakage upon replication stress known to drive chromosome rearrangements during oncogenesis. Here the authors use genome-wide and single cell techniques to assess how replication timing and transcriptional activity correlate with genome stability.
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