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Yang SF, Nelson CB, Wells JK, Fernando M, Lu R, Allen JAM, Malloy L, Lamm N, Murphy VJ, Mackay JP, Deans AJ, Cesare AJ, Sobinoff AP, Pickett HA. ZNF827 is a single-stranded DNA binding protein that regulates the ATR-CHK1 DNA damage response pathway. Nat Commun 2024; 15:2210. [PMID: 38472229 PMCID: PMC10933417 DOI: 10.1038/s41467-024-46578-0] [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: 06/15/2022] [Accepted: 03/04/2024] [Indexed: 03/14/2024] Open
Abstract
The ATR-CHK1 DNA damage response pathway becomes activated by the exposure of RPA-coated single-stranded DNA (ssDNA) that forms as an intermediate during DNA damage and repair, and as a part of the replication stress response. Here, we identify ZNF827 as a component of the ATR-CHK1 kinase pathway. We demonstrate that ZNF827 is a ssDNA binding protein that associates with RPA through concurrent binding to ssDNA intermediates. These interactions are dependent on two clusters of C2H2 zinc finger motifs within ZNF827. We find that ZNF827 accumulates at stalled forks and DNA damage sites, where it activates ATR and promotes the engagement of homologous recombination-mediated DNA repair. Additionally, we demonstrate that ZNF827 depletion inhibits replication initiation and sensitizes cancer cells to the topoisomerase inhibitor topotecan, revealing ZNF827 as a therapeutic target within the DNA damage response pathway.
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Affiliation(s)
- Sile F Yang
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Christopher B Nelson
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Jadon K Wells
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Madushan Fernando
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Robert Lu
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Joshua A M Allen
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Lisa Malloy
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Noa Lamm
- Nuclear Dynamics Group, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Vincent J Murphy
- Genome Stability Unit, St Vincent's Institute, Fitzroy, VIC, 3065, Australia
| | - Joel P Mackay
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Andrew J Deans
- Genome Stability Unit, St Vincent's Institute, Fitzroy, VIC, 3065, Australia
- Department of Medicine (St Vincent's), University of Melbourne, Fitzroy, VIC, 3065, Australia
| | - Anthony J Cesare
- Genome Integrity Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Alexander P Sobinoff
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia
| | - Hilda A Pickett
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW, 2145, Australia.
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Muralidhara P, Kumar A, Chaurasia MK, Bansal K. Topoisomerases in Immune Cell Development and Function. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2023; 210:126-133. [PMID: 36596219 PMCID: PMC7614072 DOI: 10.4049/jimmunol.2200650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 09/30/2022] [Indexed: 01/04/2023]
Abstract
DNA topoisomerases (TOPs) are complex enzymatic machines with extraordinary capacity to maintain DNA topology during torsion-intensive steps of replication and transcription. Recently, TOPs have gained significant attention for their tissue-specific function, and the vital role of TOPs in immune homeostasis and dysfunction is beginning to emerge. TOPs have been implicated in various immunological disorders such as autoimmunity, B cell immunodeficiencies, and sepsis, underscoring their importance in immune regulation. However, much remains unknown about immunological underpinnings of TOPs, and a deeper understanding of the role of TOPs in the immune system will be critical for yielding significant insights into the etiology of immunological disorders. In this review, we first discuss the recent literature highlighting the contribution of TOPs in the development of immune cells, and we further provide an overview of their importance in immune cell responses.
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Affiliation(s)
- Prerana Muralidhara
- Molecular Biology and Genetics Unit (MBGU), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064, India
| | - Amit Kumar
- Molecular Biology and Genetics Unit (MBGU), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064, India
| | - Mukesh Kumar Chaurasia
- Molecular Biology and Genetics Unit (MBGU), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064, India
| | - Kushagra Bansal
- Molecular Biology and Genetics Unit (MBGU), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur, Bangalore 560064, India,Corresponding author ()
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Pommier Y, Nussenzweig A, Takeda S, Austin C. Human topoisomerases and their roles in genome stability and organization. Nat Rev Mol Cell Biol 2022; 23:407-427. [PMID: 35228717 PMCID: PMC8883456 DOI: 10.1038/s41580-022-00452-3] [Citation(s) in RCA: 148] [Impact Index Per Article: 74.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/06/2022] [Indexed: 12/15/2022]
Abstract
Human topoisomerases comprise a family of six enzymes: two type IB (TOP1 and mitochondrial TOP1 (TOP1MT), two type IIA (TOP2A and TOP2B) and two type IA (TOP3A and TOP3B) topoisomerases. In this Review, we discuss their biochemistry and their roles in transcription, DNA replication and chromatin remodelling, and highlight the recent progress made in understanding TOP3A and TOP3B. Because of recent advances in elucidating the high-order organization of the genome through chromatin loops and topologically associating domains (TADs), we integrate the functions of topoisomerases with genome organization. We also discuss the physiological and pathological formation of irreversible topoisomerase cleavage complexes (TOPccs) as they generate topoisomerase DNA–protein crosslinks (TOP-DPCs) coupled with DNA breaks. We discuss the expanding number of redundant pathways that repair TOP-DPCs, and the defects in those pathways, which are increasingly recognized as source of genomic damage leading to neurological diseases and cancer. Topoisomerases have essential roles in transcription, DNA replication, chromatin remodelling and, as recently revealed, 3D genome organization. However, topoisomerases also generate DNA–protein crosslinks coupled with DNA breaks, which are increasingly recognized as a source of disease-causing genomic damage.
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Topoisomerase IIIβ Deficiency Induces Neuro-Behavioral Changes and Brain Connectivity Alterations in Mice. Int J Mol Sci 2021; 22:ijms222312806. [PMID: 34884616 PMCID: PMC8657541 DOI: 10.3390/ijms222312806] [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: 10/13/2021] [Revised: 11/19/2021] [Accepted: 11/24/2021] [Indexed: 11/17/2022] Open
Abstract
Topoisomerase IIIβ (Top3β), the only dual-activity topoisomerase in mammals that can change topology of both DNA and RNA, is known to be associated with neurodevelopment and mental dysfunction in humans. However, there is no report showing clear associations of Top3β with neuropsychiatric phenotypes in mice. Here, we investigated the effect of Top3β on neuro-behavior using newly generated Top3β deficient (Top3β-/-) mice. We found that Top3β-/- mice showed decreased anxiety and depression-like behaviors. The lack of Top3β was also associated with changes in circadian rhythm. In addition, a clear expression of Top3β was demonstrated in the central nervous system of mice. Positron emission tomography/computed tomography (PET/CT) analysis revealed significantly altered connectivity between many brain regions in Top3β-/- mice, including the connectivity between the olfactory bulb and the cerebellum, the connectivity between the amygdala and the olfactory bulb, and the connectivity between the globus pallidus and the optic nerve. These connectivity alterations in brain regions are known to be linked to neurodevelopmental as well as psychiatric and behavioral disorders in humans. Therefore, we conclude that Top3β is essential for normal brain function and behavior in mice and that Top3β could be an interesting target to study neuropsychiatric disorders in humans.
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Cristini A, Géraud M, Sordet O. Transcription-associated DNA breaks and cancer: A matter of DNA topology. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 364:195-240. [PMID: 34507784 DOI: 10.1016/bs.ircmb.2021.05.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Transcription is an essential cellular process but also a major threat to genome integrity. Transcription-associated DNA breaks are particularly detrimental as their defective repair can induce gene mutations and oncogenic chromosomal translocations, which are hallmarks of cancer. The past few years have revealed that transcriptional breaks mainly originate from DNA topological problems generated by the transcribing RNA polymerases. Defective removal of transcription-induced DNA torsional stress impacts on transcription itself and promotes secondary DNA structures, such as R-loops, which can induce DNA breaks and genome instability. Paradoxically, as they relax DNA during transcription, topoisomerase enzymes introduce DNA breaks that can also endanger genome integrity. Stabilization of topoisomerases on chromatin by various anticancer drugs or by DNA alterations, can interfere with transcription machinery and cause permanent DNA breaks and R-loops. Here, we review the role of transcription in mediating DNA breaks, and discuss how deregulation of topoisomerase activity can impact on transcription and DNA break formation, and its connection with cancer.
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Affiliation(s)
- Agnese Cristini
- Cancer Research Center of Toulouse, INSERM, Université de Toulouse, Université Toulouse III Paul Sabatier, CNRS, Toulouse, France.
| | - Mathéa Géraud
- Cancer Research Center of Toulouse, INSERM, Université de Toulouse, Université Toulouse III Paul Sabatier, CNRS, Toulouse, France
| | - Olivier Sordet
- Cancer Research Center of Toulouse, INSERM, Université de Toulouse, Université Toulouse III Paul Sabatier, CNRS, Toulouse, France.
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McKie SJ, Neuman KC, Maxwell A. DNA topoisomerases: Advances in understanding of cellular roles and multi-protein complexes via structure-function analysis. Bioessays 2021; 43:e2000286. [PMID: 33480441 PMCID: PMC7614492 DOI: 10.1002/bies.202000286] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/06/2020] [Accepted: 12/17/2020] [Indexed: 12/15/2022]
Abstract
DNA topoisomerases, capable of manipulating DNA topology, are ubiquitous and indispensable for cellular survival due to the numerous roles they play during DNA metabolism. As we review here, current structural approaches have revealed unprecedented insights into the complex DNA-topoisomerase interaction and strand passage mechanism, helping to advance our understanding of their activities in vivo. This has been complemented by single-molecule techniques, which have facilitated the detailed dissection of the various topoisomerase reactions. Recent work has also revealed the importance of topoisomerase interactions with accessory proteins and other DNA-associated proteins, supporting the idea that they often function as part of multi-enzyme assemblies in vivo. In addition, novel topoisomerases have been identified and explored, such as topo VIII and Mini-A. These new findings are advancing our understanding of DNA-related processes and the vital functions topos fulfil, demonstrating their indispensability in virtually every aspect of DNA metabolism.
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Affiliation(s)
- Shannon J. McKie
- Department Biological Chemistry, John Innes Centre, Norwich, UK
- Laboratory of Single Molecule Biophysics, NHLBI, Bethesda, Maryland, USA
| | - Keir C. Neuman
- Laboratory of Single Molecule Biophysics, NHLBI, Bethesda, Maryland, USA
| | - Anthony Maxwell
- Department Biological Chemistry, John Innes Centre, Norwich, UK
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Saha S, Sun Y, Huang SYN, Baechler SA, Pongor LS, Agama K, Jo U, Zhang H, Tse-Dinh YC, Pommier Y. DNA and RNA Cleavage Complexes and Repair Pathway for TOP3B RNA- and DNA-Protein Crosslinks. Cell Rep 2020; 33:108569. [PMID: 33378676 PMCID: PMC7859927 DOI: 10.1016/j.celrep.2020.108569] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 11/20/2020] [Accepted: 12/07/2020] [Indexed: 12/31/2022] Open
Abstract
The present study demonstrates that topoisomerase 3B (TOP3B) forms both RNA and DNA cleavage complexes (TOP3Bccs) in vivo and reveals a pathway for repairing TOP3Bccs. For inducing and detecting cellular TOP3Bccs, we engineer a “self-trapping” mutant of TOP3B (R338W-TOP3B). Transfection with R338W-TOP3B induces R-loops, genomic damage, and growth defect, which highlights the importance of TOP3Bcc repair mechanisms. To determine how cells repair TOP3Bccs, we deplete tyrosyl-DNA phosphodiesterases (TDP1 and TDP2). TDP2-deficient cells show elevated TOP3Bccs both in DNA and RNA. Conversely, overexpression of TDP2 lowers cellular TOP3Bccs. Using recombinant human TDP2, we demonstrate that TDP2 can process both denatured and proteolyzed TOP3Bccs. We also show that cellular TOP3Bccs are ubiquitinated by the E3 ligase TRIM41 before undergoing proteasomal processing and excision by TDP2. Saha et al. introduce an approach to generate and detect the catalytic intermediates of TOP3B in DNA and RNA by engineering a self-poisoning enzyme, R338W-TOP3B. They reveal the cellular consequences of abortive TOP3Bcc formation and a repair pathway involving TRIM41, the proteasome, and TDP2 for processing of TOP3Bcc.
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Affiliation(s)
- Sourav Saha
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Yilun Sun
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Shar-Yin Naomi Huang
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Simone Andrea Baechler
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Lorinc Sandor Pongor
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Keli Agama
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Ukhyun Jo
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Hongliang Zhang
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Yuk-Ching Tse-Dinh
- Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA; Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Yves Pommier
- Developmental Therapeutics Branch & Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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Tang R, Yu Q. Novel variants in women with premature ovarian function decline identified via whole-exome sequencing. J Assist Reprod Genet 2020; 37:2487-2502. [PMID: 32789750 DOI: 10.1007/s10815-020-01919-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 08/06/2020] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To investigate the potential etiologies of premature ovarian insufficiency (POI) and diminished ovarian reserve (DOR). METHODS Fourteen women with sporadic POI and 6 women with DOR were enrolled. We used whole-exome sequencing (WES) and bioinformatics analysis to identify variants in a subset of 599 selected POI candidate genes. The identified genes were subjected to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and protein-protein interaction (PPI) network analyses to uncover key genes and pathways. RESULTS Among the 20 patients, 79 heterozygous variants were detected in 49 genes, which were classified as "likely pathogenic" or "variants of uncertain significance" according to the guidelines of the American College of Medical Genetics and Genomics. Most patients (17/20) carried two or more variants. Monoacylglycerol O-acyltransferase 1 mutations were found in six patients, and cytochrome P450 family 26 subfamily B member 1 and Bardet-Biedl syndrome 9 mutations were each found in four patients. Some variants were shared between DOR and POI. Enrichment analyses showed that the identified genes participate in key ovarian processes, such as follicular development, gonadal development, meiosis, Fanconi anemia, homologous recombination, and transforming growth factor β signaling. A PPI network revealed interactions between these proteins. CONCLUSION Premature ovarian function decline may be polygenic, and overlap exists between the genetic backgrounds of DOR and POI. WES and in silico analyses may be a useful clinical tool for etiological diagnosis and risk prediction for high-risk women in the future.
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Affiliation(s)
- Ruiyi Tang
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, People's Republic of China
| | - Qi Yu
- Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, 100730, People's Republic of China.
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Abstract
The double-helical structure of genomic DNA is both elegant and functional in that it serves both to protect vulnerable DNA bases and to facilitate DNA replication and compaction. However, these design advantages come at the cost of having to evolve and maintain a cellular machinery that can manipulate a long polymeric molecule that readily becomes topologically entangled whenever it has to be opened for translation, replication, or repair. If such a machinery fails to eliminate detrimental topological entanglements, utilization of the information stored in the DNA double helix is compromised. As a consequence, the use of B-form DNA as the carrier of genetic information must have co-evolved with a means to manipulate its complex topology. This duty is performed by DNA topoisomerases, which therefore are, unsurprisingly, ubiquitous in all kingdoms of life. In this review, we focus on how DNA topoisomerases catalyze their impressive range of DNA-conjuring tricks, with a particular emphasis on DNA topoisomerase III (TOP3). Once thought to be the most unremarkable of topoisomerases, the many lives of these type IA topoisomerases are now being progressively revealed. This research interest is driven by a realization that their substrate versatility and their ability to engage in intimate collaborations with translocases and other DNA-processing enzymes are far more extensive and impressive than was thought hitherto. This, coupled with the recent associations of TOP3s with developmental and neurological pathologies in humans, is clearly making us reconsider their undeserved reputation as being unexceptional enzymes.
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Affiliation(s)
- Anna H Bizard
- Center for Chromosome Stability and Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark
| | - 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
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Sun CH, Weng SC, Wu JH, Tung SY, Su LH, Lin MH, Lee GA. DNA topoisomerase IIIβ promotes cyst generation by inducing cyst wall protein gene expression in Giardia lamblia. Open Biol 2020; 10:190228. [PMID: 32019477 PMCID: PMC7058931 DOI: 10.1098/rsob.190228] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Giardia lamblia causes waterborne diarrhoea by transmission of infective cysts. Three cyst wall proteins are highly expressed in a concerted manner during encystation of trophozoites into cysts. However, their gene regulatory mechanism is still largely unknown. DNA topoisomerases control topological homeostasis of genomic DNA during replication, transcription and chromosome segregation. They are involved in a variety of cellular processes including cell cycle, cell proliferation and differentiation, so they may be valuable drug targets. Giardia lamblia possesses a type IA DNA topoisomerase (TOP3β) with similarity to the mammalian topoisomerase IIIβ. We found that TOP3β was upregulated during encystation and it possessed DNA-binding and cleavage activity. TOP3β can bind to the cwp promoters in vivo using norfloxacin-mediated topoisomerase immunoprecipitation assays. We also found TOP3β can interact with MYB2, a transcription factor involved in the coordinate expression of cwp1-3 genes during encystation. Interestingly, overexpression of TOP3β increased expression of cwp1-3 and myb2 genes and cyst formation. Microarray analysis confirmed upregulation of cwp1-3 and myb2 genes by TOP3β. Mutation of the catalytically important Tyr residue, deletion of C-terminal zinc ribbon domain or further deletion of partial catalytic core domain reduced the levels of cleavage activity, cwp1-3 and myb2 gene expression, and cyst formation. Interestingly, some of these mutant proteins were mis-localized to cytoplasm. Using a CRISPR/Cas9 system for targeted disruption of top3β gene, we found a significant decrease in cwp1-3 and myb2 gene expression and cyst number. Our results suggest that TOP3β may be functionally conserved, and involved in inducing Giardia cyst formation.
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Affiliation(s)
- Chin-Hung Sun
- Department of Tropical Medicine and Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, Republic of China
| | - Shih-Che Weng
- Department of Tropical Medicine and Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, Republic of China
| | - Jui-Hsuan Wu
- Department of Tropical Medicine and Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, Republic of China
| | - Szu-Yu Tung
- Department of Tropical Medicine and Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, Republic of China
| | - Li-Hsin Su
- Department of Tropical Medicine and Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, Republic of China
| | - Meng-Hsuan Lin
- Department of Tropical Medicine and Parasitology, College of Medicine, National Taiwan University, Taipei 100, Taiwan, Republic of China
| | - Gilbert Aaron Lee
- Department of Medical Research, Taipei Medical University Hospital, Taipei, Taiwan, Republic of China
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Zhang T, Wallis M, Petrovic V, Challis J, Kalitsis P, Hudson DF. Loss of TOP3B leads to increased R-loop formation and genome instability. Open Biol 2019; 9:190222. [PMID: 31795919 PMCID: PMC6936252 DOI: 10.1098/rsob.190222] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 11/01/2019] [Indexed: 12/19/2022] Open
Abstract
Topoisomerase III beta (TOP3B) is one of the least understood members of the topoisomerase family of proteins and remains enigmatic. Our recent data shed light on the function and relevance of TOP3B to disease. A homozygous deletion for the TOP3B gene was identified in a patient with bilateral renal cancer. Analyses in both patient and modelled human cells show the disruption of TOP3B causes genome instability with a rise in DNA damage and chromosome bridging (mis-segregation). The primary molecular defect underlying this pathology is a significant increase in R-loop formation. Our data show that TOP3B is necessary to prevent the accumulation of excessive R-loops and identify TOP3B as a putative cancer gene, and support recent data showing that R-loops are involved in cancer aetiology.
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Affiliation(s)
- Tao Zhang
- Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
| | - Mathew Wallis
- Tasmanian Clinical Genetics Services, Royal Hobart Hospital, Hobart, Tasmania 7001, Australia
- School of Medicine and Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Vida Petrovic
- Cytogenetics Department, Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Jackie Challis
- Cytogenetics Department, Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Paul Kalitsis
- Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- Cytogenetics Department, Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
| | - Damien F. Hudson
- Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
- Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Melbourne, Victoria 3052, Australia
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Roles of Topoisomerases in Heterochromatin, Aging, and Diseases. Genes (Basel) 2019; 10:genes10110884. [PMID: 31683993 PMCID: PMC6896002 DOI: 10.3390/genes10110884] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 10/23/2019] [Accepted: 10/26/2019] [Indexed: 12/11/2022] Open
Abstract
Heterochromatin is a transcriptionally repressive chromatin architecture that has a low abundance of genes but an enrichment of transposons. Defects in heterochromatin can cause the de-repression of genes and transposons, leading to deleterious physiological changes such as aging, cancer, and neurological disorders. While the roles of topoisomerases in many DNA-based processes have been investigated and reviewed, their roles in heterochromatin formation and function are only beginning to be understood. In this review, we discuss recent findings on how topoisomerases can promote heterochromatin organization and impact the transcription of genes and transposons. We will focus on two topoisomerases: Top2α, which catenates and decatenates double-stranded DNA, and Top3β, which can change the topology of not only DNA, but also RNA. Both enzymes are required for normal heterochromatin formation and function, as the inactivation of either protein by genetic mutations or chemical inhibitors can result in defective heterochromatin formation and the de-silencing of transposons. These defects may contribute to the shortened lifespan and neurological disorders observed in individuals carrying mutations of Top3β. We propose that topological stress may be generated in both DNA and RNA during heterochromatin formation and function, which depend on multiple topoisomerases to resolve.
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Nitiss KC, Nitiss JL, Hanakahi LA. DNA Damage by an essential enzyme: A delicate balance act on the tightrope. DNA Repair (Amst) 2019; 82:102639. [PMID: 31437813 DOI: 10.1016/j.dnarep.2019.102639] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 06/18/2019] [Accepted: 07/01/2019] [Indexed: 01/07/2023]
Abstract
DNA topoisomerases are essential for DNA metabolic processes such as replication and transcription. Since DNA is double stranded, the unwinding needed for these processes results in DNA supercoiling and catenation of replicated molecules. Changing the topology of DNA molecules to relieve supercoiling or resolve catenanes requires that DNA be transiently cut. While topoisomerases carry out these processes in ways that minimize the likelihood of genome instability, there are several ways that topoisomerases may fail. Topoisomerases can be induced to fail by therapeutic small molecules such as by fluoroquinolones that target bacterial topoisomerases, or a variety of anti-cancer agents that target the eukaryotic enzymes. Increasingly, there have been a large number of agents and processes, including natural products and their metabolites, DNA damage, and the intrinsic properties of the enzymes that can lead to long-lasting DNA breaks that subsequently lead to genome instability, cancer, and other diseases. Understanding the processes that can interfere with topoisomerases and how cells respond when topoisomerases fail will be important in minimizing the consequences when enzymes need to transiently interfere with DNA integrity.
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Affiliation(s)
- Karin C Nitiss
- University of Illinois College of Medicine, Department of Biomedical Sciences, Rockford, IL, 61107, United States; University of Illinois College of Pharmacy, Biopharmaceutical Sciences Department, Rockford IL, 61107, United States
| | - John L Nitiss
- University of Illinois College of Pharmacy, Biopharmaceutical Sciences Department, Rockford IL, 61107, United States.
| | - Leslyn A Hanakahi
- University of Illinois College of Pharmacy, Biopharmaceutical Sciences Department, Rockford IL, 61107, United States.
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14
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Wu D, Chen Y, Chen Q, Wang G, Xu X, Peng A, Hao J, He J, Huang L, Dai J. Clinical presentation and genetic profiles of Chinese patients with velocardiofacial syndrome in a large referral centre. J Genet 2019; 98:42. [PMID: 31204702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Diagnosis and treatment of velocardiofacial syndrome (VCFS) with variable genotypes and phenotypes are considered to be very complicated. Establishing an exact correlation between the phenotypes and genotypes of VCFS is still a challenging. In this paper, 88 Chinese VCFS patients were divided into five groups based on palatal anomalies and one or two of other four common phenotypes, and copy number variations (CNVs) were detected using multiplex ligation-dependent probe amplification (MLPA), array comparative genomic hybridization (aCGH) and quantitative polymerase chain reaction. The findings showed that palatal anomalies and characteristic malformation of face were important indicators for 22q11.2 microdeletion, and there was difference inthe phenotypic spectrum between the duplication and deletion of 22q11.2. MLPA was a highly cost-effective, sensitive and preferred method for patients with 22q11.2 deletion or duplication. Our results also firstly reported that all three patients who simultaneously exhibited palatal anomalies and cognitive disorder, without other phenotypes, have Top3b duplication, which strongly suggested that Top3b may be a pathogenic gene for these patients. Further, the findings showed that patients with palatal anomalies and congenital heart disease or immune deficiency, with or without other uncommon phenotypes, exhibited heterogeneity in CNVs, including 4q34.1-qter, 6q25.3, 4q23, Xp11.4, 13q21.1, 17q23.2, 7p21.3, 2p11.2, 11q24.3 and 16q23.3, and some possible pathogenic genes, including BCOR, PRR20A, TBX2, SMYD1, KLKB1 and TULP4 have been suggested. For these patients, aCGH, whole genomic sequencing,combined with references and phenomics database to find pathogenic gene,may be choices of priority. Taking these findings together, we offered an alternative method for diagnosis of Chinese VCFS patients based on this phenotypic strategy.
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Affiliation(s)
- Dandan Wu
- Department of Oral and Cranio-maxillo facial Surgery, National Clinical Research Center for Oral Disease, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200011, People's Republic of China.
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15
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Wu D, Chen Y, Chen Q, Wang G, Xu X, Peng A, Hao J, He J, Huang L, Dai J. Clinical presentation and genetic profiles of Chinese patients with velocardiofacial syndrome in a large referral centre. J Genet 2019. [DOI: 10.1007/s12041-019-1090-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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16
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Twist and Turn-Topoisomerase Functions in Mitochondrial DNA Maintenance. Int J Mol Sci 2019; 20:ijms20082041. [PMID: 31027213 PMCID: PMC6514783 DOI: 10.3390/ijms20082041] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 12/15/2022] Open
Abstract
Like any genome, mitochondrial DNA (mtDNA) also requires the action of topoisomerases to resolve topological problems in its maintenance, but for a long time, little was known about mitochondrial topoisomerases. The last years have brought a closer insight into the function of these fascinating enzymes in mtDNA topology regulation, replication, transcription, and segregation. Here, we summarize the current knowledge about mitochondrial topoisomerases, paying special attention to mammalian mitochondrial genome maintenance. We also discuss the open gaps in the existing knowledge of mtDNA topology control and the potential involvement of mitochondrial topoisomerases in human pathologies. While Top1mt, the only exclusively mitochondrial topoisomerase in mammals, has been studied intensively for nearly a decade, only recent studies have shed some light onto the mitochondrial function of Top2β and Top3α, enzymes that are shared between nucleus and mitochondria. Top3α mediates the segregation of freshly replicated mtDNA molecules, and its dysfunction leads to mtDNA aggregation and copy number depletion in patients. Top2β, in contrast, regulates mitochondrial DNA replication and transcription through the alteration of mtDNA topology, a fact that should be acknowledged due to the frequent use of Topoisomerase 2 inhibitors in medical therapy.
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17
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Lee SK, Xue Y, Shen W, Zhang Y, Joo Y, Ahmad M, Chinen M, Ding Y, Ku WL, De S, Lehrmann E, Becker KG, Lei EP, Zhao K, Zou S, Sharov A, Wang W. Topoisomerase 3β interacts with RNAi machinery to promote heterochromatin formation and transcriptional silencing in Drosophila. Nat Commun 2018; 9:4946. [PMID: 30470739 PMCID: PMC6251927 DOI: 10.1038/s41467-018-07101-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 10/04/2018] [Indexed: 12/31/2022] Open
Abstract
Topoisomerases solve topological problems during DNA metabolism, but whether they participate in RNA metabolism remains unclear. Top3β represents a family of topoisomerases carrying activities for both DNA and RNA. Here we show that in Drosophila, Top3β interacts biochemically and genetically with the RNAi-induced silencing complex (RISC) containing AGO2, p68 RNA helicase, and FMRP. Top3β and RISC mutants are similarly defective in heterochromatin formation and transcriptional silencing by position-effect variegation assay. Moreover, both Top3β and AGO2 mutants exhibit reduced levels of heterochromatin protein HP1 in heterochromatin. Furthermore, expression of several genes and transposable elements in heterochromatin is increased in the Top3β mutant. Notably, Top3β mutants defective in either RNA binding or catalytic activity are deficient in promoting HP1 recruitment and silencing of transposable elements. Our data suggest that Top3β may act as an RNA topoisomerase in siRNA-guided heterochromatin formation and transcriptional silencing. Topoisomerases solve topological problems during DNA metabolism, but their role in RNA metabolism remains unclear. Here the authors provide evidence that in Drosophila, Topoisomerase 3β interacts biochemically and genetically with the RNAi-induced silencing complex (RISC) to promote heterochromatin formation and transcriptional silencing.
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Affiliation(s)
- Seung Kyu Lee
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Yutong Xue
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Weiping Shen
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Yongqing Zhang
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Yuyoung Joo
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Muzammil Ahmad
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Madoka Chinen
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive Kidney Diseases, Bethesda, MD, 20892, USA
| | - Yi Ding
- System Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Wai Lim Ku
- System Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Supriyo De
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Elin Lehrmann
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Kevin G Becker
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Elissa P Lei
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive Kidney Diseases, Bethesda, MD, 20892, USA
| | - Keji Zhao
- System Biology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Sige Zou
- Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Alexei Sharov
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA
| | - Weidong Wang
- Lab of Genetics and Genomics, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA.
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18
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Fan F, Li X, Pang B, Zhang C, Li Z, Zhang L, Li J, Zhang J, Yan M, Liang W, Kan B. The outer-membrane protein TolC of Vibrio cholerae serves as a second cell-surface receptor for the VP3 phage. J Biol Chem 2017; 293:4000-4013. [PMID: 29259138 DOI: 10.1074/jbc.m117.805689] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 12/14/2017] [Indexed: 12/17/2022] Open
Abstract
Receptor recognition is a key step in the initiation of phage infection. Previously, we found that VP3, the T7 family phage of the Vibrio cholerae serogroup O1 biotype El Tor, can adsorb the core oligosaccharide (OS) of lipopolysaccharides of V. cholerae However, some wildtype strains of V. cholerae possessing the intact OS gene cluster still have VP3 binding but are resistant to VP3 infection. Moreover, an OS gene-deletion mutant still exhibits weak VP3 binding, suggesting multiple factors are possibly involved in VP3 binding to V. cholerae Here, we report that the outer-membrane protein TolC of V. cholerae is involved in the host adsorption of VP3. We observed that TolC directly interacts with the VP3 tail fiber protein gp44 and its C-terminal domains, and we also found that three amino acid residues in the outside loops of TolC, at positions 78, 290, and 291, are critical for binding to gp44. Among the VP3-resistant wildtype V. cholerae strains, frequent amino acid residue mutations were observed in the loops around the sites 78, 290, and 291, which were predicted to be exposed to the cell surface. These findings reveal a co-receptor-binding mechanism for VP3 infection of V. cholerae and that both outer-membrane TolC and OS are necessary for successful VP3 infection of V. cholerae We conclude that mutations on the outside loops of the receptor may confer V. cholerae strains with VP3 phage resistance, enabling these strains to survive in environments containing VP3 or related phages.
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Affiliation(s)
- Fenxia Fan
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206
| | - Xu Li
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206
| | - Bo Pang
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206
| | - Cheng Zhang
- the National Institute of Biological Sciences, Beijing 102206, China
| | - Zhe Li
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206
| | - Lijuan Zhang
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206
| | - Jie Li
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206
| | - Jingyun Zhang
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206
| | - Meiying Yan
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206
| | - Weili Liang
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206.,the Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang 310003, and
| | - Biao Kan
- From the State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, .,the Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang 310003, and
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19
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Goto-Ito S, Yamagata A, Takahashi TS, Sato Y, Fukai S. Structural basis of the interaction between Topoisomerase IIIβ and the TDRD3 auxiliary factor. Sci Rep 2017; 7:42123. [PMID: 28176834 PMCID: PMC5296760 DOI: 10.1038/srep42123] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 01/03/2017] [Indexed: 11/09/2022] Open
Abstract
Topoisomerase IIIβ (TOP3β) is a DNA/RNA topoisomerase that has been implicated in epigenetic or translational control of gene expression. In cells, TOP3β co-exists with its specific auxiliary factor, TDRD3. TDRD3 serves as a scaffold protein to recruit TOP3β to its DNA/RNA substrates accumulating in specific cellular sites such as methylated chromatins or neural stress granules. Here we report the crystal structures of the catalytic domain of TOP3β, the DUF1767–OB-fold domains of TDRD3 and their complex at 3.44 Å, 1.62 Å and 3.6 Å resolutions, respectively. The toroidal-shaped catalytic domain of TOP3β binds the OB-fold domain of TDRD3. The TDRD3 OB-fold domain harbors the insertion loop, which is protruding from the core structure. Both the insertion loop and core region interact with TOP3β. Our pull-down binding assays showed that hydrophobic characters of the core surface and the amino- and carboxy-terminal regions of the insertion loop are essential for the interaction. Furthermore, by comparison with the structure of the homologous Topoisomerase IIIα (TOP3α)–RMI1 complex, we identified Arg96, Val109, Phe139 and the short insertion loop of TDRD3 as the critical structural elements for the specific interaction with TOP3β to avoid the non-cognate interaction with TOP3α.
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Affiliation(s)
- Sakurako Goto-Ito
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan
| | - Atsushi Yamagata
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8501, Japan
| | - Tomio S Takahashi
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan
| | - Yusuke Sato
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8501, Japan
| | - Shuya Fukai
- Structural Biology Laboratory, Structural Life Science Division, Synchrotron Radiation Research Organization and Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo 113-0032, Japan.,CREST, JST, Saitama 332-0012, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8501, Japan
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20
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Affiliation(s)
- Giovanni Capranico
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
8/2, 40126 Bologna, Italy
| | - Jessica Marinello
- Department
of Pharmacy and Biotechnology, University of Bologna, Via Belmeloro
8/2, 40126 Bologna, Italy
| | - Giovanni Chillemi
- SCAI
SuperComputing Applications and Innovation Department, Cineca, Via dei Tizii 6, 00185 Rome, Italy
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21
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Balaña-Fouce R, Alvarez-Velilla R, Fernández-Prada C, García-Estrada C, Reguera RM. Trypanosomatids topoisomerase re-visited. New structural findings and role in drug discovery. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2014; 4:326-37. [PMID: 25516844 PMCID: PMC4266802 DOI: 10.1016/j.ijpddr.2014.07.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
There is an urgent need of new treatments against trypanosomatids-borne diseases. DNA topoisomerases are pointed as potential drug targets against unicellular parasites. Trypanosomatids have a full set of DNA topoisomerases in both nucleus and kinetoplast. TopII and TopIII are located in the kinetoplast and fully involved in kDNA replication. Tritryps TopIB differ in structure from mammalian’s pointing to an attractive target.
The Trypanosomatidae family, composed of unicellular parasites, causes severe vector-borne diseases that afflict human populations worldwide. Chagas disease, sleeping sickness, as well as different sorts of leishmaniases are amongst the most important infectious diseases produced by Trypanosoma cruzi, Trypanosoma brucei and Leishmania spp., respectively. All these infections are closely related to weak health care services in low-income populations of less developed and least economically developed countries. Search for new therapeutic targets in order to hit these pathogens is of paramount priority, as no effective vaccine is currently in use against any of these parasites. Furthermore, present-day chemotherapy comprises old-fashioned drugs full of important side effects. Besides, they are prone to produce tolerance and resistance as a consequence of their continuous use for decades. DNA topoisomerases (Top) are ubiquitous enzymes responsible for solving the torsional tensions caused during replication and transcription processes, as well as in maintaining genomic stability during DNA recombination. As the inhibition of these enzymes produces cell arrest and triggers cell death, Top inhibitors are among the most effective and most widely used drugs in both cancer and antibacterial therapies. Top relaxation and decatenation activities, which are based on a common nicking–closing cycle involving one or both DNA strands, have been pointed as a promising drug target. Specific inhibitors that bind to the interface of DNA-Top complexes can stabilize Top-mediated transient DNA breaks. In addition, important structural differences have been found between Tops from the Trypanosomatidae family members and Tops from the host. Such dissimilarities make these proteins very interesting for drug design and molecular intervention. The present review is a critical update of the last findings regarding trypanosomatid’s Tops, their new structural features, their involvement both in the physiology and virulence of these parasites, as well as their use as promising targets for drug discovery.
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Affiliation(s)
- Rafael Balaña-Fouce
- Departamento de Ciencias Biomédicas, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | - Raquel Alvarez-Velilla
- Departamento de Ciencias Biomédicas, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | | | - Carlos García-Estrada
- Departamento de Ciencias Biomédicas, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | - Rosa M Reguera
- Departamento de Ciencias Biomédicas, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
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22
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Alpatov R, Lesch BJ, Nakamoto-Kinoshita M, Blanco A, Chen S, Stützer A, Armache KJ, Simon MD, Xu C, Ali M, Murn J, Prisic S, Kutateladze TG, Vakoc CR, Min J, Kingston RE, Fischle W, Warren ST, Page DC, Shi Y. A chromatin-dependent role of the fragile X mental retardation protein FMRP in the DNA damage response. Cell 2014; 157:869-81. [PMID: 24813610 DOI: 10.1016/j.cell.2014.03.040] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 02/04/2014] [Accepted: 03/20/2014] [Indexed: 01/18/2023]
Abstract
Fragile X syndrome, a common form of inherited intellectual disability, is caused by loss of the fragile X mental retardation protein FMRP. FMRP is present predominantly in the cytoplasm, where it regulates translation of proteins that are important for synaptic function. We identify FMRP as a chromatin-binding protein that functions in the DNA damage response (DDR). Specifically, we show that FMRP binds chromatin through its tandem Tudor (Agenet) domain in vitro and associates with chromatin in vivo. We also demonstrate that FMRP participates in the DDR in a chromatin-binding-dependent manner. The DDR machinery is known to play important roles in developmental processes such as gametogenesis. We show that FMRP occupies meiotic chromosomes and regulates the dynamics of the DDR machinery during mouse spermatogenesis. These findings suggest that nuclear FMRP regulates genomic stability at the chromatin interface and may impact gametogenesis and some developmental aspects of fragile X syndrome.
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Affiliation(s)
- Roman Alpatov
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Bluma J Lesch
- Howard Hughes Medical Institute, Whitehead Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Mika Nakamoto-Kinoshita
- Departments of Human Genetics, Biochemistry, and Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Andres Blanco
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Shuzhen Chen
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Alexandra Stützer
- Laboratory of Chromatin Biochemistry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Karim J Armache
- Massachusetts General Hospital, Department of Molecular Biology and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Matthew D Simon
- Massachusetts General Hospital, Department of Molecular Biology and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Chao Xu
- Structural Genomics Consortium and Department of Physiology, University of Toronto, Toronto ON M5G 1L7, Canada
| | - Muzaffar Ali
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jernej Murn
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Sladjana Prisic
- Division of Infectious Diseases, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Tatiana G Kutateladze
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | | | - Jinrong Min
- Structural Genomics Consortium and Department of Physiology, University of Toronto, Toronto ON M5G 1L7, Canada
| | - Robert E Kingston
- Massachusetts General Hospital, Department of Molecular Biology and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Wolfgang Fischle
- Laboratory of Chromatin Biochemistry, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Stephen T Warren
- Departments of Human Genetics, Biochemistry, and Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - David C Page
- Howard Hughes Medical Institute, Whitehead Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Yang Shi
- Division of Newborn Medicine, Boston Children's Hospital, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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23
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Hsieh MY, Fan JR, Chang HW, Chen HC, Shen TL, Teng SC, Yeh YH, Li TK. DNA topoisomerase III alpha regulates p53-mediated tumor suppression. Clin Cancer Res 2014; 20:1489-501. [PMID: 24526736 DOI: 10.1158/1078-0432.ccr-13-1997] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Human DNA topoisomerase III alpha (hTOP3α) is involved in DNA repair surveillance and cell-cycle checkpoints possibly through formatting complex with tumor suppressors. However, its role in cancer development remained unsolved. EXPERIMENTAL DESIGN Coimmunoprecipitation, sucrose gradient, chromatin immunoprecipitation (ChIP), real time PCR, and immunoblotting analyses were performed to determine interactions of hTOP3α with p53. Paired cell lines with different hTOP3α levels were generated via ectopic expression and short hairpin RNA (shRNA)-mediated knockdown approaches. Cellular tumorigenic properties were analyzed using cell counting, colony formation, senescence, soft agar assays, and mouse xenograft models. RESULTS The hTOP3α isozyme binds to p53 and cofractionizes with p53 in gradients differing from fractions containing hTOP3α and BLM. Knockdown of hTOP3α expression (sh-hTOP3α) caused a higher anchorage-independent growth of nontumorigenic RHEK-1 cells. Similarly, sh-hTOP3α and ectopic expression of hTOP3α in cancer cell lines caused increased and reduced tumorigenic abilities, respectively. Genetic and mutation experiments revealed that functional hTOP3α, p53, and p21 are required for this tumor-suppressive activity. Mechanism-wise, ChIP data revealed that hTOP3α binds to the p53 and p21 promoters and positively regulates their expression. Two proteins affect promoter recruitments of each other and collaborate in p21 expression. Moreover, sh-hTOP3α and sh-p53 in AGS cells caused a similar reduction in senescence and hTOP3α mRNA levels were lower in gastric and renal tumor samples. CONCLUSION We concluded that hTOP3α interacts with p53, regulates p53 and p21 expression, and contributes to the p53-mediated tumor suppression.
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Affiliation(s)
- Mei-Yi Hsieh
- Authors' Affiliations: Department and Graduate Institute of Microbiology, College of Medicine, Department of Plan Pathology and Microbiology, College of Bioresources and Agriculture, and Center for Biotechnology, National Taiwan University, Taipei, Taiwan
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24
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Chen SH, Chan NL, Hsieh TS. New mechanistic and functional insights into DNA topoisomerases. Annu Rev Biochem 2013; 82:139-70. [PMID: 23495937 DOI: 10.1146/annurev-biochem-061809-100002] [Citation(s) in RCA: 257] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA topoisomerases are nature's tools for resolving the unique problems of DNA entanglement that occur owing to unwinding and rewinding of the DNA helix during replication, transcription, recombination, repair, and chromatin remodeling. These enzymes perform topological transformations by providing a transient DNA break, formed by a covalent adduct with the enzyme, through which strand passage can occur. The active site tyrosine is responsible for initiating two transesterifications to cleave and then religate the DNA backbone. The cleavage reaction intermediate is exploited by cytotoxic agents, which have important applications as antibiotics and anticancer drugs. The reactions mediated by these enzymes can also be regulated by their binding partners; one example is a DNA helicase capable of modulating the directionality of strand passage, enabling important functions like reannealing denatured DNA and resolving recombination intermediates. In this review, we cover recent advances in mechanistic insights into topoisomerases and their various cellular functions.
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Affiliation(s)
- Stefanie Hartman Chen
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
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25
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Lourenço J, Pereira R, Gonçalves F, Mendo S. SSH gene expression profile of Eisenia andrei exposed in situ to a naturally contaminated soil from an abandoned uranium mine. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2013; 88:16-25. [PMID: 23164450 DOI: 10.1016/j.ecoenv.2012.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/12/2012] [Accepted: 10/13/2012] [Indexed: 06/01/2023]
Abstract
The effects of the exposure of earthworms (Eisenia andrei) to contaminated soil from an abandoned uranium mine, were assessed through gene expression profile evaluation by Suppression Subtractive Hybridization (SSH). Organisms were exposed in situ for 56 days, in containers placed both in a contaminated and in a non-contaminated site (reference). Organisms were sampled after 14 and 56 days of exposure. Results showed that the main physiological functions affected by the exposure to metals and radionuclides were: metabolism, oxireductase activity, redox homeostasis and response to chemical stimulus and stress. The relative expression of NADH dehydrogenase subunit 1 and elongation factor 1 alpha was also affected, since the genes encoding these enzymes were significantly up and down-regulated, after 14 and 56 days of exposure, respectively. Also, an EST with homology for SET oncogene was found to be up-regulated. To the best of our knowledge, this is the first time that this gene was identified in earthworms and thus, further studies are required, to clarify its involvement in the toxicity of metals and radionuclides. Considering the results herein presented, gene expression profiling proved to be a very useful tool to detect earthworms underlying responses to metals and radionuclides exposure, pointing out for the detection and development of potential new biomarkers.
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Affiliation(s)
- Joana Lourenço
- Departamento de Biologia, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
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Banerjee B, Sen N, Majumder HK. Identification of a Functional Type IA Topoisomerase, LdTopIIIβ, from Kinetoplastid Parasite Leishmania donovani. Enzyme Res 2011; 2011:230542. [PMID: 21637326 PMCID: PMC3102327 DOI: 10.4061/2011/230542] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Accepted: 02/25/2011] [Indexed: 11/20/2022] Open
Abstract
DNA topoisomerases of kinetoplastids represent a family of DNA processing enzymes that essentially solve the topological problems not only in nuclear DNA but also in kinetoplast DNA. We have, for the first time, identified a Leishmania donovani homologue of bacterial and eukaryotic IA type of topoisomerase III protein and termed as LdTopIIIβ. Complementation study of wild-type and mutant LdTopIIIβ with slow-growing topoisomerase III mutant yeast S. cerevisiae revealed the functional conservation of the leishmanial counterpart of topoisomerase IIIβ protein, the 327 tyrosine being the active site amino acid. A C-terminal deletion construct of LdTopIIIβ could not suppress the slow-growth phenotype of mutant yeast, indicating the requirement of C-terminal region for the enzyme function in vivo.LdTopIIIβ localized inside the nucleus and kinetoplast of the parasite. Taken together, our study indicates functional conservation and possible role of LdTopIIIβ in parasite DNA processing.
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Affiliation(s)
- Bijoylaxmi Banerjee
- Molecular Parasitology Laboratory, Infectious Disease and Immunology Division, Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Kolkata 700032, India
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Significance of topoisomerase IIIβ expression in breast ductal carcinomas: strong associations with disease-specific survival and metastasis. Hum Pathol 2010; 41:1624-30. [PMID: 20950730 DOI: 10.1016/j.humpath.2010.01.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 01/22/2010] [Accepted: 01/27/2010] [Indexed: 11/23/2022]
Abstract
Topoisomerases are ubiquitous nuclear enzymes that regulate DNA structure in eukaryotic cells. The role of topoisomerase IIIβ, the newest member of the topoisomerase family, in the clinical outcome of breast cancer is still poorly understood. This study aims to investigate the immunoexpression of topoisomerase IIIβ in breast cancer and its relationships with clinicopathologic features and immunohistochemical markers of prognostic significance in breast pathology. Using tissue microarrays containing 171 cases of primary invasive breast cancer, we analyzed the immunoexpression of topoisomerase IIIβ, estrogen receptor, progesterone receptor, HER-2, BRCA-1, p53, and Ki67. Immunostaining for topoisomerase IIIβ was found in 33.9% of breast carcinomas, and immunopositivity was correlated with distant metastasis (P = .036) and death (P = .006). Decreased expression of topoisomerase IIIβ correlated with low expression of Ki67 (P < .001) and negativity for HER-2 (P < .001), BRCA-1 (P = .001), and p53 (P < .001). In the multivariate analysis, topoisomerase IIIβ expression was a significant predictor of survival (hazard ratio, 3.006 [95% confidence interval, 1.582-5.715]; P = .001). In conclusion, topoisomerase IIIβ expression can be a useful marker in assessing the prognosis of patients with breast cancer and is an independent predictor of survival.
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Mönnich M, Hess I, Wiest W, Bachrati C, Hickson ID, Schorpp M, Boehm T. Developing T lymphocytes are uniquely sensitive to a lack of topoisomerase III alpha. Eur J Immunol 2010; 40:2379-84. [PMID: 20623552 DOI: 10.1002/eji.201040634] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
All organisms possess at least one type IA DNA topoisomerase. These topoisomerases function as part of a DNA structure-specific "dissolvasome," also known as the RTR complex, which has critical functions in faithful DNA replication, recombination, and chromosome segregation. In humans, the heteromeric RTR complex consists of RMI1, RMI2, the Bloom's syndrome gene product (BLM), and topoisomerase 3A (TOP3A) proteins. Here, we describe the identification and characterization of two deleterious mutations in the zebrafish top3a gene that reveal an unexpected tissue-specific requirement of top3a function in developing thymocytes. Deficiency in top3a activates a p53-dependent check-point but does not affect VDJ recombination. Our results suggest that TOP3A could be a candidate gene involved in human primary immunodeficiency syndromes.
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Affiliation(s)
- Maren Mönnich
- Department of Developmental Immunology, Max-Planck Institute of Immunobiology, Freiburg, Germany
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Kawamura R, Pope LH, Christensen MO, Sun M, Terekhova K, Boege F, Mielke C, Andersen AH, Marko JF. Mitotic chromosomes are constrained by topoisomerase II-sensitive DNA entanglements. ACTA ACUST UNITED AC 2010; 188:653-63. [PMID: 20194637 PMCID: PMC2835934 DOI: 10.1083/jcb.200910085] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Chromatin entanglements undergo specific protein-mediated compaction to fold into mitotic chromosomes. We have analyzed the topological organization of chromatin inside mitotic chromosomes. We show that mitotic chromatin is heavily self-entangled through experiments in which topoisomerase (topo) II is observed to reduce mitotic chromosome elastic stiffness. Single chromosomes were relaxed by 35% by exogenously added topo II in a manner that depends on hydrolysable adenosine triphosphate (ATP), whereas an inactive topo II cleavage mutant did not change chromosome stiffness. Moreover, experiments using type I topos produced much smaller relaxation effects than topo II, indicating that chromosome relaxation by topo II is caused by decatenation and/or unknotting of double-stranded DNA. In further experiments in which chromosomes are first exposed to protease to partially release protein constraints on chromatin, ATP alone relaxes mitotic chromosomes. The topo II–specific inhibitor ICRF-187 blocks this effect, indicating that it is caused by endogenous topo II bound to the chromosome. Our experiments show that DNA entanglements act in concert with protein-mediated compaction to fold chromatin into mitotic chromosomes.
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Affiliation(s)
- Ryo Kawamura
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA
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Barratt CLR, Aitken RJ, Björndahl L, Carrell DT, de Boer P, Kvist U, Lewis SEM, Perreault SD, Perry MJ, Ramos L, Robaire B, Ward S, Zini A. Sperm DNA: organization, protection and vulnerability: from basic science to clinical applications--a position report. Hum Reprod 2010; 25:824-38. [PMID: 20139429 DOI: 10.1093/humrep/dep465] [Citation(s) in RCA: 192] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
This article reports the results of the most recent in a series of EHSRE workshops designed to synthesize the current state of the field in Andrology and provide recommendations for future work (for details see Appendix). Its focus is on methods for detecting sperm DNA damage and potential application of new knowledge about sperm chromatin organization, vulnerability and repair to improve the diagnosis and treatment of clinical infertility associated with that damage. Equally important is the use and reliability of these tests to identify the extent to which environmental contaminants or pharmaceutical agents may contribute to the incidence of sperm DNA damage and male fertility problems. A working group (for workshop details, see Appendix) under the auspices of ESHRE met in May 2009 to assess the current knowledgebase and suggest future basic and clinical research directions. This document presents a synthesis of the working group's understanding of the recent literature and collective discussions on the current state of knowledge of sperm chromatin structure and function during fertilization. It highlights the biological, assay and clinical uncertainties that require further research and ends with a series of 5 key recommendations.
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Affiliation(s)
- Christopher L R Barratt
- Reproductive and Developmental Biology, Maternal and Child Health Science Laboratories, Centre for Oncology and Molecular Medicine, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, UK.
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Plank J, Hsieh TS. Helicase-appended topoisomerases: new insight into the mechanism of directional strand transfer. J Biol Chem 2009; 284:30737-41. [PMID: 19726668 DOI: 10.1074/jbc.r109.051268] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA strand passage through an enzyme-mediated gate is a key step in the catalytic cycle of topoisomerases to produce topological transformations in DNA. In most of the reactions catalyzed by topoisomerases, strand passage is not directional; thus, the enzyme simply provides a transient DNA gate through which DNA transport is allowed and thereby resolves the topological entanglement. When studied in isolation, the type IA topoisomerase family appears to conform to this rule. Interestingly, type IA enzymes can carry out directional strand transport as well. We examined here the biochemical mechanism for directional strand passage of two type IA topoisomerases: reverse gyrase and a protein complex of topoisomerase III alpha and Bloom helicase. These enzymes are able to generate vectorial strand transport independent of the supercoiling energy stored in the DNA molecule. Reverse gyrase is able to anneal single strands, thereby increasing linkage number of a DNA molecule. However, topoisomerase III alpha and Bloom helicase can dissolve DNA conjoined with a double Holliday junction, thus reducing DNA linkage. We propose here that the helicase or helicase-like component plays a determinant role in the directionality of strand transport. There is thus a common biochemical ground for the directional strand passage for the type IA topoisomerases.
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Affiliation(s)
- Jody Plank
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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Abstract
I was born in China and would have remained there but for the tumultuous events that led many of my generation to the United States for graduate studies. Norman Davidson introduced me to DNA when I became a postdoctoral fellow in his group at the California Institute of Technology in 1964, and a fortuitous conversation there ignited my interest in DNA ring formation, which later led me to study different topological forms of DNA rings-catenanes, knots, and supercoils. In 1968, a chance observation led me to identify a new enzyme capable of converting one DNA ring form to another, an enzyme now known as a DNA topoisomerase. My interest in DNA rings and DNA topoisomerases continued throughout my years at the University of California, Berkeley, and Harvard. The fascinating ability of the topoisomerases in passing DNA strands or double helices through one another and their importance in cellular processes have kept me and many others excited in their studies.
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Affiliation(s)
- James C Wang
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
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Laberge RM, Boissonneault G. CHROMATIN REMODELING IN SPERMATIDS: A SENSITIVE STEP FOR THE GENETIC INTEGRITY OF THE MALE GAMETE. ACTA ACUST UNITED AC 2009; 51:125-33. [PMID: 15804867 DOI: 10.1080/014850190518134] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Several causes of male infertility remain idiopathic. Recently, the condensed state of the sperm head has been demonstrated as a discriminating parameter for the assessment of male infertility. Altered DNA condensation is associated with an increase in DNA strand breakage so the genetic integrity of the male gamete is threatened. The origin of the DNA strand breaks in unknown. However, transient DNA strand breaks appear in the whole population of elongating spermatids during mid-spermiogenesis steps. Most likely, these transient breaks are required to support the change in DNA topology associated with chromatin remodeling at these steps. Histones hyperacetylation is also coincident with the DNA strand breakage steps. Hyperacetylation of histones may represent a necessary condition for strand breakages to form allowing access to the yet unknown enzymatic activity involved in the removal of DNA supercoils. A better characterization of this enzyme activity at these steps is necessary as this may represent a very sensitive process where altercations in the genetic integrity of the male gamete may arise and persist up to the mature spermatozoa. During the chromatin remodeling in spermatids, the combined DNA-condensing activities provides by the basic transition proteins and protamines may optimize the strand repair process emphasizing the link between altered sperm DNA condensation and DNA fragmentation. The mutagenic potential of these events may have been overlooked as it may result in fertility and/or developmental problems.
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Affiliation(s)
- R-M Laberge
- Département de Biochimie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
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Ogilvie CM, Ahn JW, Mann K, Roberts RG, Flinter F. A novel deletion in proximal 22q associated with cardiac septal defects and microcephaly: a case report. Mol Cytogenet 2009; 2:9. [PMID: 19239688 PMCID: PMC2669095 DOI: 10.1186/1755-8166-2-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Accepted: 02/24/2009] [Indexed: 01/11/2023] Open
Abstract
Background Proximal 22q is rich in low copy repeats (LCRs) which mediate non-allelic homologous recombination and give rise to deletions and duplications of varying size depending on which LCRs are involved. Methods A child with multiple septal defects and other congenital anomalies was investigated for genome imbalance using multiplex ligation-dependent probe amplification (MLPA) for subtelomeres and microdeletion loci, followed by array comparative genomic hybridization (CGH) using oligonucleotide arrays with 44,000 probes across the genome. Results MLPA identified a single probe deletion in the SNAP29 gene within band 22q11.21. Follow-up array CGH testing revealed a ~1.4-Mb deletion from 19,405,375 bp to 20,797,502 bp, encompassing 28 genes. Conclusion This deletion is likely to be causally associated with the proband's congenital anomalies. Previous publications describing deletions in proximal 22q have reported deletions between LCRs 1 to 4, associated with 22q11 deletion syndrome; in addition, deletions between LCRs 4 and 6 have been described associated with "distal 22q11 deletion syndrome". To our knowledge, this is the first deletion which spans LCR4 and is not apparently mediated by LCRs. Comparison of the phenotypes found in conjunction with previously reported deletions, together with the function and expression patterns of genes in the deleted region reported here, suggests that haploinsufficiency for the Crk-like (CRKL) gene may be responsible for the reported cardiac abnormalities.
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Forterre P, Gadelle D. Phylogenomics of DNA topoisomerases: their origin and putative roles in the emergence of modern organisms. Nucleic Acids Res 2009; 37:679-92. [PMID: 19208647 PMCID: PMC2647321 DOI: 10.1093/nar/gkp032] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Topoisomerases are essential enzymes that solve topological problems arising from the double-helical structure of DNA. As a consequence, one should have naively expected to find homologous topoisomerases in all cellular organisms, dating back to their last common ancestor. However, as observed for other enzymes working with DNA, this is not the case. Phylogenomics analyses indicate that different sets of topoisomerases were present in the most recent common ancestors of each of the three cellular domains of life (some of them being common to two or three domains), whereas other topoisomerases families or subfamilies were acquired in a particular domain, or even a particular lineage, by horizontal gene transfers. Interestingly, two groups of viruses encode topoisomerases that are only distantly related to their cellular counterparts. To explain these observations, we suggest that topoisomerases originated in an ancestral virosphere, and that various subfamilies were later on transferred independently to different ancient cellular lineages. We also proposed that topoisomerases have played a critical role in the origin of modern genomes and in the emergence of the three cellular domains.
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Affiliation(s)
- Patrick Forterre
- Institut de Génétique et Microbiologie, Univ Paris-Sud, 91405 Orsay Cedex, France
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Abstract
The synaptonemal complex (SC) is a proteinaceous structure that physically holds the two homologous chromosomes together during meiotic prophase. First observed in 1956 by Montrose J. Moses (Duke University, Durham, North Carolina) in meiotic prophase spermatocytes of crayfish, the SC was found in many other species. Initially, the research into the SC focused on its structural characteristics, but with the availability of antibodies, the focus shifted to the protein components of the complex, and later, attention was diverted to the proteins associated with this structure at different time points during meiotic prophase. Various possible roles of this meiotic-specific structure have been debated since the discovery of the SC structure but consensus has yet to be reached. Dr. Peter Moens has been an internationally recognized expert on the SC, being involved in all of the steps and characterizing many of the structural and functional components of the complex mainly in mice but also in other species.
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Affiliation(s)
- Edyta Marcon
- Banting and Best Department of Molecular Research, CCBR, University of Toronto, Toronto, ON M5S3E1 Canada.
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Schwarzacher T. Chromosomes, recombination and proteins at meiosis--a tribute to Peter Moens (1931-2008). Chromosome Res 2008; 16:679-82. [PMID: 18668331 DOI: 10.1007/s10577-008-1251-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Defective p53 engagement after the induction of DNA damage in cells deficient in topoisomerase 3beta. Proc Natl Acad Sci U S A 2008; 105:5063-8. [PMID: 18367668 DOI: 10.1073/pnas.0801235105] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The type IA topoisomerases have been implicated in the repair of dsDNA breaks by homologous recombination and in the resolution of stalled or damaged DNA replication forks; thus, these proteins play important roles in the maintenance of genomic stability. We studied the functions of one of the two mammalian type IA enzymes, Top3beta, using murine embryonic fibroblasts (MEFs) derived from top3beta(-/-) embryos. top3beta(-/-) MEFs proliferated more slowly than TOP3beta(+/+) control MEFs, demonstrated increased sensitivity to DNA-damaging agents such as ionizing and UV radiation, and had increased DNA double-strand breaks as manifested by increased gamma-H2-AX phosphorylation. However, incomplete enforcement of the G(1)-S cell cycle checkpoint was observed in top3beta(-/-) MEFs. Notably, ataxia-telangiectasia, mutated (ATM)/ATM and Rad3-related (ATR)-dependent substrate phosphorylation after UV-B and ionizing radiation was impaired in top3beta(-/-) versus TOP3beta(+/+) control MEFs, and impaired up-regulation of total and Ser-18-phosphorylated p53 was observed in top3beta(-/-) cells. Taken together, these results suggest an unanticipated role for Top3beta beyond DNA repair in the activation of cellular responses to DNA damage.
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Deweese JE, Osheroff MA, Osheroff N. DNA Topology and Topoisomerases: Teaching a "Knotty" Subject. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2008; 37:2-10. [PMID: 19225573 PMCID: PMC2643378 DOI: 10.1002/bmb.20244] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
DNA is essentially an extremely long double-stranded rope in which the two strands are wound about one another. As a result, topological properties of the genetic material, including DNA underwinding and overwinding, knotting, and tangling, profoundly influence virtually every major nucleic acid process. Despite the importance of DNA topology, it is a conceptionally difficult subject to teach, because it requires students to visualize three-dimensional relationships. This article will familiarize the reader with the concept of DNA topology and offer practical approaches and demonstrations to teaching this "knotty" subject in the classroom. Furthermore, it will discuss topoisomerases, the enzymes that regulate the topological state of DNA in the cell. These ubiquitous enzymes perform a number of critical cellular functions by generating transient breaks in the double helix. During this catalytic event, topoisomerases maintain genomic stability by forming covalent phosphotyrosyl bonds between active site residues and the newly generated DNA termini. Topoisomerases are essential for cell survival. However, because they cleave the genetic material, these enzymes also have the potential to fragment the genome. This latter feature of topoisomerases is exploited by some of the most widely prescribed anticancer and antibacterial drugs currently in clinical use. Finally, in addition to curing cancer, topoisomerase action also has been linked to the induction of specific types of leukemia.
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Affiliation(s)
- Joseph E. Deweese
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
| | | | - Neil Osheroff
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
- Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146
- To whom correspondence should be addressed: Department of Biochemistry, 654 Robinson Research Building, Vanderbilt University School of Medicine, Nashville, TN 37232-0146. Tel: 1-615-322-4338; Fax: 1-615-343-1166; E-Mail:
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Kwan KY, Greenwald RJ, Mohanty S, Sharpe AH, Shaw AC, Wang JC. Development of autoimmunity in mice lacking DNA topoisomerase 3beta. Proc Natl Acad Sci U S A 2007; 104:9242-7. [PMID: 17517607 PMCID: PMC1890479 DOI: 10.1073/pnas.0703587104] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mice lacking DNA topoisomerase 3beta are predisposed to a shortened lifespan, infertility, and lesions in multiple organs resulting from inflammatory responses. Examination of the immune system of 6- and 52-week-old top3beta(-/-) mice revealed no significant aberrations in their central and peripheral tolerance or in T lymphocyte activation. However, the older but not the younger cohort shows a high incidence of serum autoantibodies relative to their TOP3beta(+/+) age-mates. The mutant mice also show an increase in numerical aberrations of chromosomes in splenocytes and bone marrow cells, as well as an increase in apoptotic cells in the thymus. Thus, it appears plausible that the inflammatory lesions in top3beta(-/-) mice are caused by the development of autoimmunity as they age: Chromosomal abnormalities in top3beta(-/-) mice might lead to a persistent increase in apoptotic cells, which might in turn lead to the progression of autoimmunity.
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Affiliation(s)
- Kelvin Y. Kwan
- *Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138
| | - Rebecca J. Greenwald
- Immunology Research Division, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115; and
| | - Subhasis Mohanty
- Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT 06520
| | - Arlene H. Sharpe
- Immunology Research Division, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115; and
| | - Albert C. Shaw
- Section of Infectious Diseases, Yale University School of Medicine, New Haven, CT 06520
- To whom correspondence may be addressed. E-mail: or
| | - James C. Wang
- *Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138
- To whom correspondence may be addressed. E-mail: or
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Chicheportiche A, Bernardino-Sgherri J, de Massy B, Dutrillaux B. Characterization of Spo11-dependent and independent phospho-H2AX foci during meiotic prophase I in the male mouse. J Cell Sci 2007; 120:1733-42. [PMID: 17456548 DOI: 10.1242/jcs.004945] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Meiotic DNA double strand breaks (DSBs) are indicated at leptotene by the phosphorylated form of histone H2AX (gamma-H2AX). In contrast to previous studies, we identified on both zygotene and pachytene chromosomes two distinct types of gamma-H2AX foci: multiple small (S) foci located along autosomal synaptonemal complexes (SCs) and larger signals on chromatin loops (L-foci). The S-foci number gradually declined throughout pachytene, in parallel with the repair of DSBs monitored by repair proteins suggesting that S-foci mark DSB repair events. We validated this interpretation by showing the absence of S-foci in Spo11(-/-) spermatocytes. By contrast, the L-foci number was very low through pachytene. Based on the analysis of gamma-H2AX labeling after irradiation of spermatocytes, the formation of DSBs clearly induced L-foci formation. Upon DSB repair, these foci appear to be processed and lead to the above mentioned S-foci. The presence of L-foci in wild-type pachytene and diplotene could therefore reflect delayed or unregulated DSB repair events. Interestingly, their distribution was different in Spo11(+/-) spermatocytes compared with Spo11(+/+) spermatocytes, where DSB repair might be differently regulated as a response to homeostatic control of crossing-over. The presence of these L-foci in Spo11(-/-) spermatocytes raises the interesting possibility of yet uncharacterized alterations in DNA or chromosome structure in Spo11(-/-) cells.
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Affiliation(s)
- Alexandra Chicheportiche
- Laboratory of Differentiation and Radiobiology of the Gonads, Unit of Gametogenesis and Genotoxicity, Unité Mixte de Recherche-S 566, Commissariat à l'Energie Atomique DSV/IRCM/SEGG/LDRG, F-92265 Fontenay aux Roses, France.
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Viard T, de la Tour CB. Type IA topoisomerases: a simple puzzle? Biochimie 2006; 89:456-67. [PMID: 17141394 DOI: 10.1016/j.biochi.2006.10.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2006] [Accepted: 10/20/2006] [Indexed: 11/30/2022]
Abstract
Type IA topoisomerases are enzymes that can modify DNA topology. They form a distinct family of proteins present in all domains of life, from bacteria to archaea and higher eukaryotes. They are composed of two domains: a core domain containing all the conserved motifs involved in the trans-esterification reactions, and a carboxyl-terminal domain that is highly variable in size and sequence. The latter appears to interact with other proteins, defining the physiological use of the topoisomerase activity. The evolutionary relevance of this topoisomerase-cofactor complex, also known as the "toposome", as well as its enzymatic consequences are discussed in this review.
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Affiliation(s)
- Thierry Viard
- Nicholas Cozzarelli Laboratory, Molecular and Cell Biology Department, 16 Barker Hall, University of California, Berkeley, CA 94720-3204, USA.
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Mankouri HW, Hickson ID. Top3 processes recombination intermediates and modulates checkpoint activity after DNA damage. Mol Biol Cell 2006; 17:4473-83. [PMID: 16899506 PMCID: PMC1635375 DOI: 10.1091/mbc.e06-06-0516] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Mutation of TOP3 in Saccharomyces cerevisiae causes poor growth, hyperrecombination, and a failure to fully activate DNA damage checkpoints in S phase. Here, we report that overexpression of a dominant-negative allele of TOP3, TOP3(Y356F), which lacks the catalytic (decatenation) activity of Top3, causes impaired S-phase progression and the persistence of abnormal DNA structures (X-shaped DNA molecules) after exposure to methylmethanesulfonate. The impaired S-phase progression is due to a persistent checkpoint-mediated cell cycle delay and can be overridden by addition of caffeine. Hence, the catalytic activity of Top3 is not required for DNA damage checkpoint activation, but it is required for normal S-phase progression after DNA damage. We also present evidence that the checkpoint-mediated cell cycle delay and persistence of X-shaped DNA molecules resulting from overexpression of TOP3(Y356F) are downstream of Rad51 function. We propose that Top3 functions in S phase to both process homologous recombination intermediates and modulate checkpoint activity.
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Affiliation(s)
- Hocine W. Mankouri
- Cancer Research UK Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
| | - Ian D. Hickson
- Cancer Research UK Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom
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Plank JL, Wu J, Hsieh TS. Topoisomerase IIIalpha and Bloom's helicase can resolve a mobile double Holliday junction substrate through convergent branch migration. Proc Natl Acad Sci U S A 2006; 103:11118-23. [PMID: 16849422 PMCID: PMC1544052 DOI: 10.1073/pnas.0604873103] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It has long been suspected that a double Holliday junction (dHJ) could be resolved by a topoisomerase partnered with a helicase by convergent branch migration of the HJs. Genetic analysis of yeast TOP3 and SGS1 has lent considerable evidence to the notion that the protein products of these genes are involved in just such a process, although biochemical analysis of the metabolism of a dHJ has been hindered by the lack of a substrate that adequately replicates the endogenous structure. We have synthesized a dHJ substrate that recapitulates many of the features of an endogenous dHJ and represents a much earlier intermediate in the resolution pathway. Here, we show that Drosophila topoisomerase IIIalpha (Topo IIIalpha) and Blm (a homolog of Sgs1) are capable of resolving this substrate to non-cross-over products and that this activity is stimulated by replication protein A (RPA). We investigated the ability of other Drosophila topoisomerases to perform this reaction in concert with Blm and RPA and discovered that this resolution activity is unique to Topo IIIalpha. Examination of the mechanism of resolution reveals that Topo IIIalpha, Blm, and RPA resolve this substrate by convergent migration of the two HJs toward each other, collapsing the dHJ. This mechanism stands in contrast to classic resolvase activities that use a structure-specific endonuclease to cleave the HJs.
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Affiliation(s)
- Jody L. Plank
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
| | - Jianhong Wu
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
| | - Tao-shih Hsieh
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710
- *To whom correspondence should be addressed at:
Department of Biochemistry, Duke University Medical Center, DUMC Box 3711, Durham, NC 27710. E-mail:
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Cohen PE, Pollack SE, Pollard JW. Genetic analysis of chromosome pairing, recombination, and cell cycle control during first meiotic prophase in mammals. Endocr Rev 2006; 27:398-426. [PMID: 16543383 DOI: 10.1210/er.2005-0017] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Meiosis is a double-division process that is preceded by only one DNA replication event to produce haploid gametes. The defining event in meiosis is prophase I, during which chromosome pairs locate each other, become physically connected, and exchange genetic information. Although many aspects of this process have been elucidated in lower organisms, there has been scant information available until now about the process in mammals. Recent advances in genetic analysis, especially in mice and humans, have revealed many genes that play essential roles in meiosis in mammals. These include cell cycle-regulatory proteins that couple the exit from the premeiotic DNA synthesis to the progression through prophase I, the chromosome structural proteins involved in synapsis, and the repair and recombination proteins that process the recombination events. Failure to adequately repair the DNA damage caused by recombination triggers meiotic checkpoints that result in ablation of the germ cells by apoptosis. These analyses have revealed surprising sexual dimorphism in the requirements of different gene products and a much less stringent checkpoint regulation in females. This may provide an explanation for the 10-fold increase in meiotic errors in females compared with males. This review provides a comprehensive analysis of the use of genetic manipulation, particularly in mice, but also of the analysis of mutations in humans, to elucidate the mechanisms that are required for traverse through prophase I.
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Affiliation(s)
- P E Cohen
- Department of Molecular Genetics, Center for the Study of Reproduction and Women's Health, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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Wu J, Hou JH, Hsieh TS. A new Drosophila gene wh (wuho) with WD40 repeats is essential for spermatogenesis and has maximal expression in hub cells. Dev Biol 2006; 296:219-30. [PMID: 16762337 PMCID: PMC2055424 DOI: 10.1016/j.ydbio.2006.04.459] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 04/20/2006] [Accepted: 04/21/2006] [Indexed: 01/16/2023]
Abstract
Through mutagenesis by P-element transposition, we identified a series of mutants with deletions in topoisomerase 3beta gene (top3beta) and an adjacent, previously uncharacterized gene CG15897, here named wuho (wh). Whereas top3beta truncation does not affect viability or fertility, wh null mutants display male sterile and female semi-sterile phenotypes. Furthermore, wh mutants can be fully rescued by wh transgenes, but not by top3beta transgenes, suggesting that the fertility phenotypes are caused by wh deletion. The alignment of WH protein sequence with other eukaryotic putative homologues shows they are evolutionarily conserved proteins with 5 WD40 repeats in the middle portion of the protein, and a bipartite nuclear localization signal at the carboxyl terminus. Yeast homologue with 5 WD40 repeats, Trm82, is the non-catalytic subunit of a tRNA methylase. Immunostaining shows that WH has the highest expression in hub cells, a niche for germline stem cells of testis. However, WH is not required for the maintenance of hub cells or the germline stem cells. In wh mutant males, spermatogenesis is arrested at the elongating stage of the developing spermatids, resulting in an absence of mature sperms in the seminal vesicles. The decreased fertility in wh mutant females is mostly due to defects in oogenesis. There are abnormal egg chambers present in the mutant females, in which the cystocytes fail to arrest their cell division at the fourth mitotic cycle, resulting in more than 16 cells in a single egg chamber. Additionally, these abnormal cystocytes do not undergo multiple rounds of endoreplication as the nurse cells do in a normal egg chamber. Therefore, the cytological analyses demonstrate that wh has a critical function in cellular differentiation for germline cells during gametogenesis.
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Affiliation(s)
| | | | - Tao-shih Hsieh
- *Corresponding author. Fax: +1 919 684 8885. E-mail address: (T. Hsieh)
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Abstract
The crystal structure of the four-stranded DNA Holliday junction has now been determined in the presence and absence of junction binding proteins, with the extended open-X form of the junction seen in all protein complexes, but the more compact stacked-X structure observed in free DNA. The structures of the stacked-X junction were crystallized because of an unexpected sequence dependence on the stability of this structure. Inverted repeat sequences that contain the general motif NCC or ANC favor formation of stacked-X junctions, with the junction cross-over occurring between the first two positions of the trinucleotides. This review focuses on the sequence dependent structure of the stacked-X junction and how it may play a role in structural recognition by a class of dimeric junction resolving enzymes that themselves show no direct sequence recognition.
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Affiliation(s)
- Patricia A. Khuu
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, 97331-7305, USA
| | - Andrea Regier Voth
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, 97331-7305, USA
| | | | - P. Shing Ho
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, 97331-7305, USA
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Lopez CR, Yang S, Deibler RW, Ray SA, Pennington JM, Digate RJ, Hastings PJ, Rosenberg SM, Zechiedrich EL. A role for topoisomerase III in a recombination pathway alternative to RuvABC. Mol Microbiol 2006; 58:80-101. [PMID: 16164551 DOI: 10.1111/j.1365-2958.2005.04812.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The physiological role of topoisomerase III is unclear for any organism. We show here that the removal of topoisomerase III in temperature sensitive topoisomerase IV mutants in Escherichia coli results in inviability at the permissive temperature. The removal of topoisomerase III has no effect on the accumulation of catenated intermediates of DNA replication, even when topoisomerase IV activity is removed. Either recQ or recA null mutations, but not helD null or lexA3, partially rescued the synthetic lethality of the double topoisomerase III/IV mutant, indicating a role for topoisomerase III in recombination. We find a bias against deleting the gene encoding topoisomerase III in ruvC53 or DeltaruvABC backgrounds compared with the isogenic wild-type strains. The topoisomerase III RuvC double mutants that can be constructed are five- to 10-fold more sensitive to UV irradiation and mitomycin C treatment and are twofold less efficient in transduction efficiency than ruvC53 mutants. The overexpression of ruvABC allows the construction of the topoisomerase III/IV double mutant. These data are consistent with a role for topoisomerase III in disentangling recombination intermediates as an alternative to RuvABC to maintain the stability of the genome.
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Affiliation(s)
- Christopher R Lopez
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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Abstract
Bacillus cereus topoisomerase IIIbeta (bcTopo IIIbeta) has been cloned, overexpressed and biochemically characterized. This enzyme exhibits 64% and 33% sequence identity to Bacillus subtilis topoisomerase III (bsTopo III) and Escherichia coli topoisomerase III (ecTopo III) respectively. The enzymatic properties of bcTopo IIIbeta differ substantially from other bacterial type IA topoisomerases, including E. coli type IA topoisomerases and B. cereus topoisomerase I (bcTopo I) and IIIalpha (bcTopo IIIalpha). bcTopo IIIbeta only partially relaxes negatively supercoiled DNA and appears incapable of generating fully relaxed topoisomers. In contrast to ecTopo III and bcTopo IIIalpha, bcTopo IIIbeta is not a decatenase. bcTopo IIIbeta is unable to compensate the loss of ecTopo III in vivo. Therefore, bcTopo IIIbeta is a unique prokaryotic type IA topoisomerase that is different from previously characterized topoisomerases.
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Affiliation(s)
- Zhiyu Li
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, USA
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