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Maharaj AV, Cottrell E, Thanasupawat T, Joustra SD, Triggs-Raine B, Fujimoto M, Kant SG, van der Kaay D, Clement-de Boers A, Brooks AS, Aguirre GA, Martín del Estal I, Castilla de Cortázar Larrea MI, Massoud A, van Duyvenvoorde HA, De Bruin C, Hwa V, Klonisch T, Hombach-Klonisch S, Storr HL. Characterization of HMGA2 variants expands the spectrum of Silver-Russell syndrome. JCI Insight 2024; 9:e169425. [PMID: 38516887 PMCID: PMC11063932 DOI: 10.1172/jci.insight.169425] [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: 02/16/2023] [Accepted: 02/08/2024] [Indexed: 03/23/2024] Open
Abstract
Silver-Russell syndrome (SRS) is a heterogeneous disorder characterized by intrauterine and postnatal growth retardation. HMGA2 variants are a rare cause of SRS and its functional role in human linear growth is unclear. Patients with suspected SRS negative for 11p15LOM/mUPD7 underwent whole-exome and/or targeted-genome sequencing. Mutant HMGA2 protein expression and nuclear localization were assessed. Two Hmga2-knockin mouse models were generated. Five clinical SRS patients harbored HMGA2 variants with differing functional impacts: 2 stop-gain nonsense variants (c.49G>T, c.52C>T), c.166A>G missense variant, and 2 frameshift variants (c.144delC, c.145delA) leading to an identical, extended-length protein. Phenotypic features were highly variable. Nuclear localization was reduced/absent for all variants except c.166A>G. Homozygous knockin mice recapitulating the c.166A>G variant (Hmga2K56E) exhibited a growth-restricted phenotype. An Hmga2Ter76-knockin mouse model lacked detectable full-length Hmga2 protein, similarly to patient 3 and 5 variants. These mice were infertile, with a pygmy phenotype. We report a heterogeneous group of individuals with SRS harboring variants in HMGA2 and describe the first Hmga2 missense knockin mouse model (Hmga2K56E) to our knowledge causing a growth-restricted phenotype. In patients with clinical features of SRS but negative genetic screening, HMGA2 should be included in next-generation sequencing testing approaches.
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Affiliation(s)
- Avinaash V. Maharaj
- Centre for Endocrinology, William Harvey Research Institute, QMUL, London, United Kingdom
| | - Emily Cottrell
- Centre for Endocrinology, William Harvey Research Institute, QMUL, London, United Kingdom
| | - Thatchawan Thanasupawat
- Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Sjoerd D. Joustra
- Division of Paediatric Endocrinology, Department of Paediatrics, Willem-Alexander Children’s Hospital, Leiden University Medical Centre, Leiden, Netherlands
| | - Barbara Triggs-Raine
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Masanobu Fujimoto
- Cincinnati Center for Growth Disorders, Division of Endocrinology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, USA
| | - Sarina G. Kant
- Division of Paediatric Endocrinology, Department of Paediatrics, Willem-Alexander Children’s Hospital, Leiden University Medical Centre, Leiden, Netherlands
| | - Danielle van der Kaay
- Division of Paediatric Endocrinology, Department of Paediatrics, Erasmus University Medical Centre, Sophia Children’s Hospital, Rotterdam, Netherlands
| | - Agnes Clement-de Boers
- Department of Paediatrics, Juliana Children’s Hospital/Haga Teaching Hospital, The Hague, Netherlands
| | - Alice S. Brooks
- Department of Clinical Genetics, Erasmus MC University Medical Center, Rotterdam, Netherlands
| | | | | | | | - Ahmed Massoud
- Department of Paediatrics and Child Health, HCA Healthcare UK, London, United Kingdom
| | - Hermine A. van Duyvenvoorde
- Laboratory for Diagnostic Genome analysis (LDGA), Department of Clinical Genetics, Leiden University Medical Centre, Leiden, Netherlands
| | - Christiaan De Bruin
- Division of Paediatric Endocrinology, Department of Paediatrics, Willem-Alexander Children’s Hospital, Leiden University Medical Centre, Leiden, Netherlands
| | - Vivian Hwa
- Cincinnati Center for Growth Disorders, Division of Endocrinology, Cincinnati Children’s Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, USA
| | - Thomas Klonisch
- Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Pathology, and
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Sabine Hombach-Klonisch
- Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Pathology, and
| | - Helen L. Storr
- Centre for Endocrinology, William Harvey Research Institute, QMUL, London, United Kingdom
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2
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Lau MS, Hu Z, Zhao X, Tan YS, Liu J, Huang H, Yeo CJ, Leong HF, Grinchuk OV, Chan JK, Yan J, Tee WW. Transcriptional repression by a secondary DNA binding surface of DNA topoisomerase I safeguards against hypertranscription. Nat Commun 2023; 14:6464. [PMID: 37833256 PMCID: PMC10576097 DOI: 10.1038/s41467-023-42078-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 09/28/2023] [Indexed: 10/15/2023] Open
Abstract
Regulation of global transcription output is important for normal development and disease, but little is known about the mechanisms involved. DNA topoisomerase I (TOP1) is an enzyme well-known for its role in relieving DNA supercoils for enabling transcription. Here, we report a non-enzymatic function of TOP1 that downregulates RNA synthesis. This function is dependent on specific DNA-interacting residues located on a conserved protein surface. A loss-of-function knock-in mutation on this surface, R548Q, is sufficient to cause hypertranscription and alter differentiation outcomes in mouse embryonic stem cells (mESCs). Hypertranscription in mESCs is accompanied by reduced TOP1 chromatin binding and change in genomic supercoiling. Notably, the mutation does not impact TOP1 enzymatic activity; rather, it diminishes TOP1-DNA binding and formation of compact protein-DNA structures. Thus, TOP1 exhibits opposing influences on transcription through distinct activities which are likely to be coordinated. This highlights TOP1 as a safeguard of appropriate total transcription levels in cells.
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Affiliation(s)
- Mei Sheng Lau
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore.
| | - Zhenhua Hu
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore
- Department of Obstetrics and Gynecology, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, Guangzhou, China
- Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, Guangzhou, China
- Guangdong-Hong Kong-Macao Greater Bay Area Higher Education Joint Laboratory of Maternal-Fetal Medicine, Guangzhou, China
- The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Xiaodan Zhao
- Department of Physics, National University of Singapore, Singapore, 117551, Singapore
- Centre for Bioimaging Sciences, National University of Singapore, Singapore, 117557, Singapore
| | - Yaw Sing Tan
- Bioinformatics Institute (BII), A*STAR, 30 Biopolis Street, Matrix, Singapore, 138671, Singapore
| | - Jinyue Liu
- Genome Institute of Singapore (GIS), A*STAR, 60 Biopolis Street, Genome, Singapore, 138672, Singapore
| | - Hua Huang
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Electrophysiology Core Facility, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Clarisse Jingyi Yeo
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore
| | - Hwei Fen Leong
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore
| | - Oleg V Grinchuk
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore
| | - Justin Kaixuan Chan
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore
| | - Jie Yan
- Department of Physics, National University of Singapore, Singapore, 117551, Singapore.
- Centre for Bioimaging Sciences, National University of Singapore, Singapore, 117557, Singapore.
- Mechanobiology Institute, National University of Singapore, Singapore, 117411, Singapore.
| | - Wee-Wei Tee
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore.
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
- NUS Centre for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
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3
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The Functional Consequences of Eukaryotic Topoisomerase 1 Interaction with G-Quadruplex DNA. Genes (Basel) 2020; 11:genes11020193. [PMID: 32059547 PMCID: PMC7073998 DOI: 10.3390/genes11020193] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/07/2020] [Accepted: 02/09/2020] [Indexed: 12/22/2022] Open
Abstract
Topoisomerase I in eukaryotic cells is an important regulator of DNA topology. Its catalytic function is to remove positive or negative superhelical tension by binding to duplex DNA, creating a reversible single-strand break, and finally religating the broken strand. Proper maintenance of DNA topological homeostasis, in turn, is critically important in the regulation of replication, transcription, DNA repair, and other processes of DNA metabolism. One of the cellular processes regulated by the DNA topology and thus by Topoisomerase I is the formation of non-canonical DNA structures. Non-canonical or non-B DNA structures, including the four-stranded G-quadruplex or G4 DNA, are potentially pathological in that they interfere with replication or transcription, forming hotspots of genome instability. In this review, we first describe the role of Topoisomerase I in reducing the formation of non-canonical nucleic acid structures in the genome. We further discuss the interesting recent discovery that Top1 and Top1 mutants bind to G4 DNA structures in vivo and in vitro and speculate on the possible consequences of these interactions.
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4
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Girstun A, Ishikawa T, Kowalska-Loth B, Czubaty A, Staron K. Subnuclear Localization of Human Topoisomerase I. J Cell Biochem 2016; 118:407-419. [DOI: 10.1002/jcb.25654] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 07/14/2016] [Indexed: 12/23/2022]
Affiliation(s)
- Agnieszka Girstun
- Department of Molecular Biology; Institute of Biochemistry; Faculty of Biology; University of Warsaw; Warsaw Poland
| | - Takao Ishikawa
- Department of Molecular Biology; Institute of Biochemistry; Faculty of Biology; University of Warsaw; Warsaw Poland
| | - Barbara Kowalska-Loth
- Department of Molecular Biology; Institute of Biochemistry; Faculty of Biology; University of Warsaw; Warsaw Poland
| | - Alicja Czubaty
- Department of Molecular Biology; Institute of Biochemistry; Faculty of Biology; University of Warsaw; Warsaw Poland
| | - Krzysztof Staron
- Department of Molecular Biology; Institute of Biochemistry; Faculty of Biology; University of Warsaw; Warsaw Poland
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5
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D'Annessa I, Coletta A, Sutthibutpong T, Mitchell J, Chillemi G, Harris S, Desideri A. Simulations of DNA topoisomerase 1B bound to supercoiled DNA reveal changes in the flexibility pattern of the enzyme and a secondary protein-DNA binding site. Nucleic Acids Res 2014; 42:9304-12. [PMID: 25056319 PMCID: PMC4132758 DOI: 10.1093/nar/gku654] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Human topoisomerase 1B has been simulated covalently bound to a negatively supercoiled DNA minicircle, and its behavior compared to the enzyme bound to a simple linear DNA duplex. The presence of the more realistic supercoiled substrate facilitates the formation of larger number of protein–DNA interactions when compared to a simple linear duplex fragment. The number of protein–DNA hydrogen bonds doubles in proximity to the active site, affecting all of the residues in the catalytic pentad. The clamp over the DNA, characterized by the salt bridge between Lys369 and Glu497, undergoes reduced fluctuations when bound to the supercoiled minicircle. The linker domain of the enzyme, which is implicated in the controlled relaxation of superhelical stress, also displays an increased number of contacts with the minicircle compared to linear DNA. Finally, the more complex topology of the supercoiled DNA minicircle gives rise to a secondary DNA binding site involving four residues located on subdomain III. The simulation trajectories reveal significant changes in the interactions between the enzyme and the DNA for the more complex DNA topology, which are consistent with the experimental observation that the protein has a preference for binding to supercoiled DNA.
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Affiliation(s)
- Ilda D'Annessa
- Department of Biology and Interuniversity Consortium, National Institute Biostructure and Biosystem (INBB), University of Rome Tor Vergata, Via Della Ricerca Scientifica, Rome 00133, Italy
| | - Andrea Coletta
- Department of Biology and Interuniversity Consortium, National Institute Biostructure and Biosystem (INBB), University of Rome Tor Vergata, Via Della Ricerca Scientifica, Rome 00133, Italy
| | | | - Jonathan Mitchell
- Division of Genetics and Epidemiology, Institute of Cancer Research, Sutton, SM2 5NG, UK
| | | | - Sarah Harris
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Alessandro Desideri
- Department of Biology and Interuniversity Consortium, National Institute Biostructure and Biosystem (INBB), University of Rome Tor Vergata, Via Della Ricerca Scientifica, Rome 00133, Italy
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6
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Anderson BG, Stivers JT. Variola type IB DNA topoisomerase: DNA binding and supercoil unwinding using engineered DNA minicircles. Biochemistry 2014; 53:4302-15. [PMID: 24945825 PMCID: PMC4089885 DOI: 10.1021/bi500571q] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Type
IB topoisomerases unwind positive and negative DNA supercoils
and play a key role in removing supercoils that would otherwise accumulate
at replication and transcription forks. An interesting question is
whether topoisomerase activity is regulated by the topological state
of the DNA, thereby providing a mechanism for targeting the enzyme
to highly supercoiled DNA domains in genomes. The type IB enzyme from
variola virus (vTopo) has proven to be useful in addressing mechanistic
questions about topoisomerase function because it forms a reversible
3′-phosphotyrosyl adduct with the DNA backbone at a specific
target sequence (5′-CCCTT-3′) from which DNA unwinding
can proceed. We have synthesized supercoiled DNA minicircles (MCs)
containing a single vTopo target site that provides highly defined
substrates for exploring the effects of supercoil density on DNA binding,
strand cleavage and ligation, and unwinding. We observed no topological
dependence for binding of vTopo to these supercoiled MC DNAs, indicating
that affinity-based targeting to supercoiled DNA regions by vTopo
is unlikely. Similarly, the cleavage and religation rates of the MCs
were not topologically dependent, but topoisomers with low superhelical
densities were found to unwind more slowly than highly supercoiled
topoisomers, suggesting that reduced torque at low superhelical densities
leads to an increased number of cycles of cleavage and ligation before
a successful unwinding event. The K271E charge reversal mutant has
an impaired interaction with the rotating DNA segment that leads to
an increase in the number of supercoils that were unwound per cleavage
event. This result provides evidence that interactions of the enzyme
with the rotating DNA segment can restrict the number of supercoils
that are unwound. We infer that both superhelical density and transient
contacts between vTopo and the rotating DNA determine the efficiency
of supercoil unwinding. Such determinants are likely to be important
in regulating the steady-state superhelical density of DNA domains
in the cell.
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Affiliation(s)
- Breeana G Anderson
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore, Maryland 21205-2185, United States
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7
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Yang Z, Li D, Guo J, Shao F, Li T. Intrinsic curvature in duplex DNA inhibits Human Topoisomerase I. Bioorg Med Chem Lett 2011; 22:1322-5. [PMID: 22227211 DOI: 10.1016/j.bmcl.2011.12.089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 12/14/2011] [Accepted: 12/16/2011] [Indexed: 11/25/2022]
Abstract
Human Topoisomerase I (hTopo I) have been known as a potential target for cancer therapy. A series of duplex DNA with different intrinsic curvatures have been designed as inhibitors to hTopo I. The activities of hTopo I on relaxing supercoiled plasmid pUC 19 are apparently diminished in the presence of the curved DNA. More potent inhibitions and smaller IC(50) are achieved by duplex DNA with higher curvatures. EMSA indicates that hTopo I can recognize the curved DNA through binding interactions. Our studies demonstrate that the activity of hTopo I can be modulated by the intrinsic curvature of linear DNA and provide a new avenue to design curved DNA as hTopo I inhibitors with high therapeutic efficiency and low toxicity.
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Affiliation(s)
- Zhaoqi Yang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, 21 Nanyang Link, Nanyang Technological University, Singapore 637371, Singapore
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8
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Rajendran A, Endo M, Sugiyama H. Single-molecule analysis using DNA origami. Angew Chem Int Ed Engl 2011; 51:874-90. [PMID: 22121063 DOI: 10.1002/anie.201102113] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Indexed: 11/11/2022]
Abstract
During the last two decades, scientists have developed various methods that allow the detection and manipulation of single molecules, which have also been called "in singulo" approaches. Fundamental understanding of biochemical reactions, folding of biomolecules, and the screening of drugs were achieved by using these methods. Single-molecule analysis was also performed in the field of DNA nanotechnology, mainly by using atomic force microscopy. However, until recently, the approaches used commonly in nanotechnology adopted structures with a dimension of 10-20 nm, which is not suitable for many applications. The recent development of scaffolded DNA origami by Rothemund made it possible for the construction of larger defined assemblies. One of the most salient features of the origami method is the precise addressability of the structures formed: Each staple can serve as an attachment point for different kinds of nanoobjects. Thus, the method is suitable for the precise positioning of various functionalities and for the single-molecule analysis of many chemical and biochemical processes. Here we summarize recent progress in the area of single-molecule analysis using DNA origami and discuss the future directions of this research.
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Affiliation(s)
- Arivazhagan Rajendran
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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9
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Rajendran A, Endo M, Sugiyama H. Einzelmolekülanalysen mithilfe von DNA-Origami. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201102113] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Yang Z, Li D, Hiew S, Ng MT, Yuan W, Su H, Shao F, Li T. Recognition of forcible curvature in circular DNA by human Topoisomerase I. Chem Commun (Camb) 2011; 47:11309-11. [PMID: 21922105 DOI: 10.1039/c1cc13904e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of forcible curved circular DNAs (cDNAs) were prepared to investigate the recognition features of human Topoisomerase I (hTopo I). The IC(50) can be modulated by the curvature degrees of cDNA. In addition, preferential bindings of hTopo I to cDNA with high curvature have been observed by AFM and EMSA.
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Affiliation(s)
- Zhaoqi Yang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
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11
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Minturn JE, Janss AJ, Fisher PG, Allen JC, Patti R, Phillips PC, Belasco JB. A phase II study of metronomic oral topotecan for recurrent childhood brain tumors. Pediatr Blood Cancer 2011; 56:39-44. [PMID: 21108437 DOI: 10.1002/pbc.22690] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND The prognosis for recurrent or refractory brain tumors in children is poor with conventional therapies. Topotecan is a topoisomerase I inhibitor with good central nervous system (CNS) penetration following oral administration. Increased efficacy of topotecan has been demonstrated with prolonged low-dose daily treatment in pre-clinical models. To investigate further this drug delivered orally in pediatric CNS malignancies, a phase II study in children with recurrent or refractory brain tumors was performed. PROCEDURE Patients ≤ 21 years of age at diagnosis with a recurrent, progressive, or refractory primary CNS malignancy and measurable disease, were eligible. Patients enrolled into four strata: ependymoma (N = 4), high-grade glioma (HGG) (N = 6), brainstem glioma (BSG) (N = 13), and primitive neuroectodermal tumor (PNET) (N = 8). Oral topotecan was administered once daily at a dose of 0.8 mg/m(2)/day for 21 consecutive days repeated every 28 days. Response and toxicity profiles were evaluated. RESULTS Twenty-six patients were evaluable (median age 9.2 years; 10 males). Two objective responses were observed in PNET patients with disseminated tumor at study entry. These two patients remain alive and in remission 7 and 9.5 years off study. Four other patients (two BSG, one PNET, and one HGG) had stable disease (median 4.6 months). The most common toxicities were hematologic. CONCLUSIONS Daily oral topotecan at a dose of 0.8 mg/m(2)/day can be safely administered to children with recurrent or refractory brain tumors. This regimen identified activity in recurrent PNET. The prolonged progression free survival (PFS) in two PNET patients justifies consideration of this regimen in more advanced clinical trials.
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Affiliation(s)
- Jane E Minturn
- Division of Oncology, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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12
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Subramani R, Juul S, Rotaru A, Andersen FF, Gothelf KV, Mamdouh W, Besenbacher F, Dong M, Knudsen BR. A novel secondary DNA binding site in human topoisomerase I unravelled by using a 2D DNA origami platform. ACS NANO 2010; 4:5969-5977. [PMID: 20828215 DOI: 10.1021/nn101662a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The biologically and clinically important nuclear enzyme human topoisomerase I relaxes both positively and negatively supercoiled DNA and binds consequently DNA with supercoils of positive or negative sign with a strong preference over relaxed DNA. One scheme to explain this preference relies on the existence of a secondary DNA binding site in the enzyme facilitating binding to DNA nodes characteristic for plectonemic DNA. Here we demonstrate the ability of human topoisomerase I to induce formation of DNA synapses at protein containing nodes or filaments using atomic force microscopy imaging. By means of a two-dimensional (2D) DNA origami platform, we monitor the interactions between a single human topoisomerase I covalently bound to one DNA fragment and a second DNA fragment protruding from the DNA origami. This novel single molecule origami-based detection scheme provides direct evidence for the existence of a secondary DNA interaction site in human topoisomerase I and lends further credence to the theory of two distinct DNA interaction sites in human topoisomerase I, possibly facilitating binding to DNA nodes characteristic for plectonemic supercoils.
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Affiliation(s)
- Ramesh Subramani
- Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, Nordre Ringgade 1, DK-8000 Aarhus C, Denmark
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13
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Patel A, Yakovleva L, Shuman S, Mondragón A. Crystal structure of a bacterial topoisomerase IB in complex with DNA reveals a secondary DNA binding site. Structure 2010; 18:725-33. [PMID: 20541510 PMCID: PMC2886027 DOI: 10.1016/j.str.2010.03.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Revised: 03/11/2010] [Accepted: 03/25/2010] [Indexed: 11/21/2022]
Abstract
Type IB DNA topoisomerases (TopIB) are monomeric enzymes that relax supercoils by cleaving and resealing one strand of duplex DNA within a protein clamp that embraces a approximately 21 DNA segment. A longstanding conundrum concerns the capacity of TopIB enzymes to stabilize intramolecular duplex DNA crossovers and form protein-DNA synaptic filaments. Here we report a structure of Deinococcus radiodurans TopIB in complex with a 12 bp duplex DNA that demonstrates a secondary DNA binding site located on the surface of the C-terminal domain. It comprises a distinctive interface with one strand of the DNA duplex and is conserved in all TopIB enzymes. Modeling of a TopIB with both DNA sites suggests that the secondary site could account for DNA crossover binding, nucleation of DNA synapsis, and generation of a filamentous plectoneme. Mutations of the secondary site eliminate synaptic plectoneme formation without affecting DNA cleavage or supercoil relaxation.
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Affiliation(s)
- Asmita Patel
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2205 Tech Drive, Evanston, Illinois 60208
| | - Lyudmila Yakovleva
- Molecular Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, New York 10065
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, New York 10065
| | - Alfonso Mondragón
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, 2205 Tech Drive, Evanston, Illinois 60208
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14
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Brewood GP, Delrow JJ, Schurr JM. Calf-Thymus Topoisomerase I Equilibrates Metastable Secondary Structure Subsequent to Relaxation of Superhelical Stress. Biochemistry 2010; 49:3367-80. [DOI: 10.1021/bi9017126] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Greg P. Brewood
- University of Washington, Department of Chemistry, Box 351700, Seattle, Washington 98195-1700
| | - Jeffrey J. Delrow
- University of Washington, Department of Chemistry, Box 351700, Seattle, Washington 98195-1700
| | - J. Michael Schurr
- University of Washington, Department of Chemistry, Box 351700, Seattle, Washington 98195-1700
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