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Singh S, Mane SS, Kasniya G, Cartaya S, Rahman MM, Maheshwari A, Motta M, Dudeja P. Enteroviral Infections in Infants. NEWBORN (CLARKSVILLE, MD.) 2022; 1:297-305. [PMID: 36304567 PMCID: PMC9599990 DOI: 10.5005/jp-journals-11002-0036] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Enteroviruses (EVs) are major pathogens in young infants. These viruses were traditionally classified into the following four subgenera: polio, coxsackie A and B, and echoviruses. Now that poliomyelitis seems to be controlled in most parts of the world, coxsackie and echoviruses are gaining more attention because (i) the structural and pathophysiological similarities and (ii) the consequent possibilities in translational medicine. Enteroviruses are transmitted mainly by oral and fecal-oral routes; the clinical manifestations include a viral prodrome including fever, feeding intolerance, and lethargy, which may be followed by exanthema; aseptic meningitis and encephalitis; pleurodynia; myopericarditis; and multi-system organ failure. Laboratory diagnosis is largely based on reverse transcriptase-polymerase chain reaction, cell culture, and serology. Prevention and treatment can be achieved using vaccination, and administration of immunoglobulins and antiviral drugs. In this article, we have reviewed the properties of these viruses, their clinical manifestations, and currently available methods of detection, treatment, and prognosis.
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Affiliation(s)
- Srijan Singh
- Department of Pediatrics, Grant Government Medical College and Sir JJ Group of Hospitals, Mumbai, Maharashtra, India
| | - Sushant Satish Mane
- Department of Pediatrics, Grant Government Medical College and Sir JJ Group of Hospitals, Mumbai, Maharashtra, India
| | - Gangajal Kasniya
- Department of Pediatrics, Cohen Children’s Medical Center, New Hyde Park, New York, United States of America
| | - Sofia Cartaya
- Department of Pediatrics, University of South Florida, Tampa, Florida, United States of America
| | - Mohd Mujibur Rahman
- Department of Neonatology, Institute of Child and Mother Health, Dhaka, Bangladesh
| | - Akhil Maheshwari
- Global Newborn Society, Clarksville, Maryland, United States of America
| | - Mario Motta
- Neonatologia e Terapia Intensiva Neonatale ASST Spedali Civili di Brescia, Italy
| | - Pradeep Dudeja
- Department of Gastroenterology, University of Illinois at Chicago, Illinois, United States of America
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2
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Holmes AC, Zagnoli-Vieira G, Caldecott KW, Semler BL. Effects of TDP2/VPg Unlinkase Activity on Picornavirus Infections Downstream of Virus Translation. Viruses 2020; 12:E166. [PMID: 32023921 PMCID: PMC7077319 DOI: 10.3390/v12020166] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 12/12/2022] Open
Abstract
In this study, we characterized the role of host cell protein tyrosyl-DNA phosphodiesterase 2 (TDP2) activity, also known as VPg unlinkase, in picornavirus infections in a human cell model of infection. TDP2/VPg unlinkase is used by picornaviruses to remove the small polypeptide, VPg (Virus Protein genome-linked, the primer for viral RNA synthesis), from virus genomic RNA. We utilized a CRISPR/Cas-9-generated TDP2 knock out (KO) human retinal pigment epithelial-1 (hRPE-1) cell line, in addition to the wild type (WT) counterpart for our studies. We determined that in the absence of TDP2, virus growth kinetics for two enteroviruses (poliovirus and coxsackievirus B3) were delayed by about 2 h. Virus titers were reduced by ~2 log10 units for poliovirus and 0.5 log10 units for coxsackievirus at 4 hours post-infection (hpi), and by ~1 log10 unit at 6 hpi for poliovirus. However, virus titers were nearly indistinguishable from those of control cells by the end of the infectious cycle. We determined that this was not the result of an alternative source of VPg unlinkase activity being activated in the absence of TPD2 at late times of infection. Viral protein production in TDP2 KO cells was also substantially reduced at 4 hpi for poliovirus infection, consistent with the observed growth kinetics delay, but reached normal levels by 6 hpi. Interestingly, this result differs somewhat from what has been reported previously for the TDP2 KO mouse cell model, suggesting that either cell type or species-specific differences might be playing a role in the observed phenotype. We also determined that catalytically inactive TDP2 does not rescue the growth defect, confirming that TDP2 5' phosphodiesterase activity is required for efficient virus replication. Importantly, we show for the first time that polysomes can assemble efficiently on VPg-linked RNA after the initial round of translation in a cell culture model, but both positive and negative strand RNA production is impaired in the absence of TDP2 at mid-times of infection, indicating that the presence of VPg on the viral RNA affects a step in the replication cycle downstream of translation (e.g., RNA synthesis). In agreement with this conclusion, we found that double-stranded RNA production (a marker of viral RNA synthesis) is delayed in TDP2 KO RPE-1 cells. Moreover, we show that premature encapsidation of nascent, VPg-linked RNA is not responsible for the observed virus growth defect. Our studies provide the first lines of evidence to suggest that either negative- or positive-strand RNA synthesis (or both) is a likely candidate for the step that requires the removal of VPg from the RNA for an enterovirus infection to proceed efficiently.
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Affiliation(s)
- Autumn C. Holmes
- Department of Microbiology & Molecular Genetics and Center for Virus Research, University of California, Irvine, CA 92697, USA;
| | - Guido Zagnoli-Vieira
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK; (G.Z.-V.); (K.W.C.)
| | - Keith W. Caldecott
- Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, UK; (G.Z.-V.); (K.W.C.)
| | - Bert L. Semler
- Department of Microbiology & Molecular Genetics and Center for Virus Research, University of California, Irvine, CA 92697, USA;
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3
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Kawale AS, Povirk LF. Tyrosyl-DNA phosphodiesterases: rescuing the genome from the risks of relaxation. Nucleic Acids Res 2019; 46:520-537. [PMID: 29216365 PMCID: PMC5778467 DOI: 10.1093/nar/gkx1219] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 11/29/2017] [Indexed: 12/13/2022] Open
Abstract
Tyrosyl–DNA Phosphodiesterases 1 (TDP1) and 2 (TDP2) are eukaryotic enzymes that clean-up after aberrant topoisomerase activity. While TDP1 hydrolyzes phosphotyrosyl peptides emanating from trapped topoisomerase I (Top I) from the 3′ DNA ends, topoisomerase 2 (Top II)-induced 5′-phosphotyrosyl residues are processed by TDP2. Even though the canonical functions of TDP1 and TDP2 are complementary, they exhibit little structural or sequence similarity. Homozygous mutations in genes encoding these enzymes lead to the development of severe neurodegenerative conditions due to the accumulation of transcription-dependent topoisomerase cleavage complexes underscoring the biological significance of these enzymes in the repair of topoisomerase–DNA lesions in the nervous system. TDP1 can promiscuously process several blocked 3′ ends generated by DNA damaging agents and nucleoside analogs in addition to hydrolyzing 3′-phosphotyrosyl residues. In addition, deficiency of these enzymes causes hypersensitivity to anti-tumor topoisomerase poisons. Thus, TDP1 and TDP2 are promising therapeutic targets and their inhibitors are expected to significantly synergize the effects of current anti-tumor therapies including topoisomerase poisons and other DNA damaging agents. This review covers the structural aspects, biology and regulation of these enzymes, along with ongoing developments in the process of discovering safe and effective TDP inhibitors.
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Affiliation(s)
- Ajinkya S Kawale
- Department of Pharmacology and Toxicology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Lawrence F Povirk
- Department of Pharmacology and Toxicology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
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4
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Komulainen E, Pennicott L, Grand DL, Caldecott KW. Deazaflavin Inhibitors of TDP2 with Cellular Activity Can Affect Etoposide Influx and/or Efflux. ACS Chem Biol 2019; 14:1110-1114. [PMID: 31091068 PMCID: PMC7613159 DOI: 10.1021/acschembio.9b00144] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Tyrosyl DNA phosphodiesterase 2 (TDP2) facilitates the repair of topoisomerase II (TOP2)-linked DNA double-strand breaks and, as a consequence, is required for cellular resistance to TOP2 "poisons". Recently, a deazaflavin series of compounds were identified as potent inhibitors of TDP2, in vitro. Here, however, we show that while some deazaflavins can induce cellular sensitivity to the TOP2 poison etoposide, they do so independently of TDP2 status. Consistent with this, both the cellular level of etoposide-induced TOP2 cleavage complexes and the intracellular concentration of etoposide was increased by incubation with deazaflavin, suggesting an impact of these compounds on etoposide uptake/efflux. In addition, deazaflavin failed to increase the level of TOP2 cleavage complexes or sensitivity induced by m-AMSA, which is a different class of TOP2 poison to which TDP2-defective cells are also sensitive. In conclusion, while deazaflavins are potent inhibitors of TDP2 in vitro, their limited cell permeability and likely interference with etoposide influx/efflux limits their utility in cells.
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Affiliation(s)
- Emilia Komulainen
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ
| | - Lewis Pennicott
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Falmer, Brighton
| | - Darren Le Grand
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Falmer, Brighton
| | - Keith W Caldecott
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9RQ
- Department of Genome Dynamics, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, 4, Czech Republic
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5
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Kankanala J, Ribeiro CJA, Kiselev E, Ravji A, Williams J, Xie J, Aihara H, Pommier Y, Wang Z. Novel Deazaflavin Analogues Potently Inhibited Tyrosyl DNA Phosphodiesterase 2 (TDP2) and Strongly Sensitized Cancer Cells toward Treatment with Topoisomerase II (TOP2) Poison Etoposide. J Med Chem 2019; 62:4669-4682. [PMID: 30998359 DOI: 10.1021/acs.jmedchem.9b00274] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Topoisomerase II (TOP2) poisons as anticancer drugs work by trapping TOP2 cleavage complexes (TOP2cc) to generate DNA damage. Repair of such damage by tyrosyl DNA phosphodiesterase 2 (TDP2) could render cancer cells resistant to TOP2 poisons. Inhibiting TDP2, thus, represents an attractive mechanism-based chemosensitization approach. Currently known TDP2 inhibitors lack cellular potency and/or permeability. We report herein two novel subtypes of the deazaflavin TDP2 inhibitor core. By introducing an additional phenyl ring to the N-10 phenyl ring (subtype 11) or to the N-3 site of the deazaflavin scaffold (subtype 12), we have generated novel analogues with considerably improved biochemical potency and/or permeability. Importantly, many analogues of both subtypes, particularly compounds 11a, 11e, 12a, 12b, and 12h, exhibited much stronger cancer cell sensitizing effect than the best previous analogue 4a toward the treatment with etoposide, suggesting that these analogues could serve as effective cellular probes.
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Affiliation(s)
| | | | - Evgeny Kiselev
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research , National Cancer Institute, National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Azhar Ravji
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research , National Cancer Institute, National Institutes of Health , Bethesda , Maryland 20892 , United States
| | | | | | | | - Yves Pommier
- Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research , National Cancer Institute, National Institutes of Health , Bethesda , Maryland 20892 , United States
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6
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Ribeiro CJA, Kankanala J, Xie J, Williams J, Aihara H, Wang Z. Triazolopyrimidine and triazolopyridine scaffolds as TDP2 inhibitors. Bioorg Med Chem Lett 2018; 29:257-261. [PMID: 30522956 DOI: 10.1016/j.bmcl.2018.11.044] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 11/12/2018] [Accepted: 11/21/2018] [Indexed: 01/09/2023]
Abstract
Tyrosyl-DNA phosphodiesterase 2 (TDP2) repairs topoisomerase II (TOP2) mediated DNA damages and causes cellular resistance to clinically used TOP2 poisons. Inhibiting TDP2 can potentially sensitize cancer cells toward TOP2 poisons. Commercial compound P10A10, to which the structure was assigned as 7-phenyl triazolopyrimidine analogue 6a, was previously identified as a TDP2 inhibitor hit in our virtual and fluorescence-based biochemical screening campaign. We report herein that the hit validation through resynthesis and structure elucidation revealed the correct structure of P10A10 (Chembridge ID 7236827) to be the 5-phenyl triazolopyrimidine regioisomer 7a. Subsequent structure-activity relationship (SAR) via the synthesis of a total of 47 analogues of both the 5-phenyl triazolopyrimidine scaffold (7) and its bioisosteric triazolopyridine scaffold (17) identified four derivatives (7a, 17a, 17e, and 17z) with significant TDP2 inhibition (IC50 < 50 µM), with 17z showing excellent cell permeability and no cytotoxicity.
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Affiliation(s)
- Carlos J A Ribeiro
- Center for Drug Design, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Jayakanth Kankanala
- Center for Drug Design, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Jiashu Xie
- Center for Drug Design, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Jessica Williams
- Center for Drug Design, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, United States
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Zhengqiang Wang
- Center for Drug Design, College of Pharmacy, University of Minnesota, Minneapolis, MN 55455, United States.
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7
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Yu LM, Hu Z, Chen Y, Ravji A, Lopez S, Plescia CB, Yu Q, Yang H, Abdelmalak M, Saha S, Agama K, Kiselev E, Marchand C, Pommier Y, An LK. Synthesis and structure-activity relationship of furoquinolinediones as inhibitors of Tyrosyl-DNA phosphodiesterase 2 (TDP2). Eur J Med Chem 2018; 151:777-796. [PMID: 29677635 DOI: 10.1016/j.ejmech.2018.04.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 04/08/2018] [Accepted: 04/10/2018] [Indexed: 10/17/2022]
Abstract
Tyrosyl-DNA phosphodiesterase 2 (TDP2) is a recently discovered enzyme specifically repairing topoisomerase II (TOP2)-mediated DNA damage. It has been shown that inhibition of TDP2 synergize with TOP2 inhibitors. Herein, we report the discovery of the furoquinolinedione chemotype as a suitable skeleton for the development of selective TDP2 inhibitors. Compound 1 was identified as a TDP2 inhibitor as a result of screening our in-house compound library for compounds selective for TDP2 vs. TDP1. Further SAR studies provide several selective TDP2 inhibitors at low-micromolar range. The most potent compound 74 shows inhibitory activity with IC50 of 1.9 and 2.1 μM against recombinant TDP2 and TDP2 in whole cell extracts (WCE), respectively.
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Affiliation(s)
- Le-Mao Yu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Zhu Hu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Yu Chen
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Azhar Ravji
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Sophia Lopez
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Caroline B Plescia
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Qian Yu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Hui Yang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Monica Abdelmalak
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Sourav Saha
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Keli Agama
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Evgeny Kiselev
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Christophe Marchand
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Yves Pommier
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, United States
| | - Lin-Kun An
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, 510006, China.
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8
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New fluorescence-based high-throughput screening assay for small molecule inhibitors of tyrosyl-DNA phosphodiesterase 2 (TDP2). Eur J Pharm Sci 2018; 118:67-79. [PMID: 29574079 DOI: 10.1016/j.ejps.2018.03.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 03/16/2018] [Accepted: 03/20/2018] [Indexed: 01/03/2023]
Abstract
Tyrosyl-DNA phosphodiesterase 2 (TDP2) repairs topoisomerase II (TOP2) mediated DNA damages and causes resistance to TOP2-targeted cancer therapy. Inhibiting TDP2 could sensitize cancer cells toward TOP2 inhibitors. However, potent TDP2 inhibitors with favorable physicochemical properties are not yet reported. Therefore, there is a need to search for novel molecular scaffolds capable of inhibiting TDP2. We report herein a new simple, robust, homogenous mix-and-read fluorescence biochemical assay based using humanized zebrafish TDP2 (14M_zTDP2), which provides biochemical and molecular structure basis for TDP2 inhibitor discovery. The assay was validated by screening a preselected library of 1600 compounds (Z' ≥ 0.72) in a 384-well format, and by running in parallel gel-based assays with fluorescent DNA substrates. This library was curated via virtual high throughput screening (vHTS) of 460,000 compounds from Chembridge Library, using the crystal structure of the novel surrogate protein 14M_zTDP2. From this primary screening, we selected the best 32 compounds (2% of the library) to further assess their TDP2 inhibition potential, leading to the IC50 determination of 10 compounds. Based on the dose-response curve profile, pan-assay interference compounds (PAINS) structure identification, physicochemical properties and efficiency parameters, two hit compounds, 11a and 19a, were tested using a novel secondary fluorescence gel-based assay. Preliminary structure-activity relationship (SAR) studies identified guanidine derivative 12a as an improved hit with a 6.4-fold increase in potency over the original HTS hit 11a. This study highlights the importance of the development of combination approaches (biochemistry, crystallography and high throughput screening) for the discovery of TDP2 inhibitors.
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9
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Maciejewski S, Ullmer W, Semler BL. VPg unlinkase/TDP2 in cardiovirus infected cells: Re-localization and proteolytic cleavage. Virology 2018; 516:139-146. [PMID: 29353210 DOI: 10.1016/j.virol.2018.01.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/05/2018] [Accepted: 01/09/2018] [Indexed: 10/18/2022]
Abstract
Cardioviruses cause diseases in many animals including, in rare cases, humans. Although they share common features with all picornaviruses, cardioviruses have unique properties that distinguish them from other family members, including enteroviruses. One feature shared by all picornaviruses is the covalent attachment of VPg to the 5' end of genomic RNA via a phosphotyrosyl linkage. For enteroviruses, this linkage is cleaved by a host cell protein, TDP2. Since TDP2 is divergently required during enterovirus infections, we determined if TDP2 is necessary during infection by the prototype cardiovirus, EMCV. We found that EMCV yields are reduced in the absence of TDP2. We observed a decrease in viral protein accumulation and viral RNA replication in the absence of TDP2. In contrast to enterovirus infections, we found that TDP2 is modified at peak times of EMCV infection. This finding suggests a unique mechanism for cardioviruses to regulate TDP2 activity during infection.
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Affiliation(s)
- Sonia Maciejewski
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Wendy Ullmer
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
| | - Bert L Semler
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA.
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10
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Hornyak P, Askwith T, Walker S, Komulainen E, Paradowski M, Pennicott LE, Bartlett EJ, Brissett NC, Raoof A, Watson M, Jordan AM, Ogilvie DJ, Ward SE, Atack JR, Pearl LH, Caldecott KW, Oliver AW. Mode of action of DNA-competitive small molecule inhibitors of tyrosyl DNA phosphodiesterase 2. Biochem J 2016; 473:1869-79. [PMID: 27099339 PMCID: PMC4925160 DOI: 10.1042/bcj20160180] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 04/19/2016] [Accepted: 04/19/2016] [Indexed: 12/27/2022]
Abstract
Tyrosyl-DNA phosphodiesterase 2 (TDP2) is a 5'-tyrosyl DNA phosphodiesterase important for the repair of DNA adducts generated by non-productive (abortive) activity of topoisomerase II (TOP2). TDP2 facilitates therapeutic resistance to topoisomerase poisons, which are widely used in the treatment of a range of cancer types. Consequently, TDP2 is an interesting target for the development of small molecule inhibitors that could restore sensitivity to topoisomerase-directed therapies. Previous studies identified a class of deazaflavin-based molecules that showed inhibitory activity against TDP2 at therapeutically useful concentrations, but their mode of action was uncertain. We have confirmed that the deazaflavin series inhibits TDP2 enzyme activity in a fluorescence-based assay, suitable for high-throughput screen (HTS)-screening. We have gone on to determine crystal structures of these compounds bound to a 'humanized' form of murine TDP2. The structures reveal their novel mode of action as competitive ligands for the binding site of an incoming DNA substrate, and point the way to generating novel and potent inhibitors of TDP2.
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Affiliation(s)
- Peter Hornyak
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, U.K. Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, U.K
| | - Trevor Askwith
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Falmer BN1 9QJ, U.K
| | - Sarah Walker
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Falmer BN1 9QJ, U.K
| | - Emilia Komulainen
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, U.K
| | - Michael Paradowski
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Falmer BN1 9QJ, U.K
| | - Lewis E Pennicott
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Falmer BN1 9QJ, U.K
| | - Edward J Bartlett
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, U.K
| | - Nigel C Brissett
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, U.K
| | - Ali Raoof
- Drug Discovery Unit, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, U.K
| | - Mandy Watson
- Drug Discovery Unit, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, U.K
| | - Allan M Jordan
- Drug Discovery Unit, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, U.K
| | - Donald J Ogilvie
- Drug Discovery Unit, Cancer Research UK Manchester Institute, University of Manchester, Manchester M20 4BX, U.K
| | - Simon E Ward
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Falmer BN1 9QJ, U.K
| | - John R Atack
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Falmer BN1 9QJ, U.K
| | - Laurence H Pearl
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, U.K.
| | - Keith W Caldecott
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, U.K.
| | - Antony W Oliver
- Cancer Research UK DNA Repair Enzymes Group, Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, U.K.
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11
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Olspert A, Hosmillo M, Chaudhry Y, Peil L, Truve E, Goodfellow I. Protein-RNA linkage and posttranslational modifications of feline calicivirus and murine norovirus VPg proteins. PeerJ 2016; 4:e2134. [PMID: 27375966 PMCID: PMC4928471 DOI: 10.7717/peerj.2134] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 05/24/2016] [Indexed: 12/01/2022] Open
Abstract
Members of the Caliciviridae family of positive sense RNA viruses cause a wide range of diseases in both humans and animals. The detailed characterization of the calicivirus life cycle had been hampered due to the lack of robust cell culture systems and experimental tools for many of the members of the family. However, a number of caliciviruses replicate efficiently in cell culture and have robust reverse genetics systems available, most notably feline calicivirus (FCV) and murine norovirus (MNV). These are therefore widely used as representative members with which to examine the mechanistic details of calicivirus genome translation and replication. The replication of the calicivirus RNA genome occurs via a double-stranded RNA intermediate that is then used as a template for the production of new positive sense viral RNA, which is covalently linked to the virus-encoded protein VPg. The covalent linkage to VPg occurs during genome replication via the nucleotidylylation activity of the viral RNA-dependent RNA polymerase. Using FCV and MNV, we used mass spectrometry-based approach to identify the specific amino acid linked to the 5′ end of the viral nucleic acid. We observed that both VPg proteins are covalently linked to guanosine diphosphate (GDP) moieties via tyrosine positions 24 and 26 for FCV and MNV respectively. These data fit with previous observations indicating that mutations introduced into these specific amino acids are deleterious for viral replication and fail to produce infectious virus. In addition, we also detected serine phosphorylation sites within the FCV VPg protein with positions 80 and 107 found consistently phosphorylated on VPg-linked viral RNA isolated from infected cells. This work provides the first direct experimental characterization of the linkage of infectious calicivirus viral RNA to the VPg protein and highlights that post-translational modifications of VPg may also occur during the viral life cycle.
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Affiliation(s)
- Allan Olspert
- Faculty of Science, Department of Gene Technology, Tallinn University of Technology , Tallinn , Estonia
| | - Myra Hosmillo
- Division of Virology, Department of Pathology, University of Cambridge , Cambridge , United Kingdom
| | - Yasmin Chaudhry
- Division of Virology, Department of Pathology, University of Cambridge , Cambridge , United Kingdom
| | - Lauri Peil
- Faculty of Science and Technology, Institute of Technology, University of Tartu , Tartu , Estonia
| | - Erkki Truve
- Faculty of Science, Department of Gene Technology, Tallinn University of Technology , Tallinn , Estonia
| | - Ian Goodfellow
- Division of Virology, Department of Pathology, University of Cambridge , Cambridge , United Kingdom
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