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The Cytomegalovirus Protein Kinase pUL97:Host Interactions, Regulatory Mechanisms and Antiviral Drug Targeting. Microorganisms 2020; 8:microorganisms8040515. [PMID: 32260430 PMCID: PMC7232230 DOI: 10.3390/microorganisms8040515] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/02/2020] [Accepted: 04/02/2020] [Indexed: 12/25/2022] Open
Abstract
Human cytomegalovirus (HCMV) expresses a variety of viral regulatory proteins that undergo close interaction with host factors including viral-cellular multiprotein complexes. The HCMV protein kinase pUL97 represents a viral cyclin-dependent kinase ortholog (vCDK) that determines the efficiency of HCMV replication via phosphorylation of viral and cellular substrates. A hierarchy of functional importance of individual pUL97-mediated phosphorylation events has been discussed; however, the most pronounced pUL97-dependent phenotype could be assigned to viral nuclear egress, as illustrated by deletion of the UL97 gene or pharmacological pUL97 inhibition. Despite earlier data pointing to a cyclin-independent functionality, experimental evidence increasingly emphasized the role of pUL97-cyclin complexes. Consequently, the knowledge about pUL97 involvement in host interaction, viral nuclear egress and additional replicative steps led to the postulation of pUL97 as an antiviral target. Indeed, validation experiments in vitro and in vivo confirmed the sustainability of this approach. Consequently, current investigations of pUL97 in antiviral treatment go beyond the known pUL97-mediated ganciclovir prodrug activation and henceforward include pUL97-specific kinase inhibitors. Among a number of interesting small molecules analyzed in experimental and preclinical stages, maribavir is presently investigated in clinical studies and, in the near future, might represent a first kinase inhibitor applied in the field of antiviral therapy.
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Hutterer C, Hamilton S, Steingruber M, Zeitträger I, Bahsi H, Thuma N, Naing Z, Örfi Z, Örfi L, Socher E, Sticht H, Rawlinson W, Chou S, Haupt VJ, Marschall M. The chemical class of quinazoline compounds provides a core structure for the design of anticytomegaloviral kinase inhibitors. Antiviral Res 2016; 134:130-143. [PMID: 27515131 DOI: 10.1016/j.antiviral.2016.08.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 07/28/2016] [Accepted: 08/05/2016] [Indexed: 12/26/2022]
Abstract
HCMV is a member of the family Herpesviridae and represents a worldwide distributed pathogen with seropositivity rates in the adult population ranging between 40% and 90%. Notably, HCMV infection is a serious, sometimes life-threatening medical problem for newborns and immunosuppressed individuals, including transplant recipients and patients under antitumoral chemotherapy. Current standard therapy with valganciclovir has the disadvantage of inducing drug-resistant virus mutants and toxicity-related side effects. Our analysis stresses the earlier finding that kinase inhibitors of the quinazoline class exert an antiviral response by targeting the viral protein kinase pUL97 without inducing resistance. Therefore, quinazolines have been used as a core structure to gain insight in the mode of inhibitor-kinase interaction. Here, we demonstrate that (i) the novel quinazolines Vi7392 and Vi7453 are highly active against HCMV laboratory and clinically relevant strains including maribavir- and ganciclovir-resistant variants, (ii) antiviral activity is not cell-type specific and was also detected in a placental explant tissue model using a genetically intact HCMV strain (iii) the viral kinase pUL97 represents a target of the anticytomegaloviral activity of these compounds, (iv) induction of pUL97-conferring drug resistance was not detectable under single-step selection, thus differed from the induction of ganciclovir resistance, and (v) pUL97 drug docking simulations enabled detailed insights into specific drug-target binding properties providing a promising basis for the design of optimized kinase inhibitors. These novel findings may open new prospects for the future medical use of quinazoline drug candidates and the use of drug-target dynamic simulations for rational design of antivirals.
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Affiliation(s)
- C Hutterer
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University (FAU) of Erlangen-Nürnberg, Erlangen, Germany.
| | - S Hamilton
- Serology and Virology Division, SEALS Microbiology Prince of Wales Hospital Randwick NSW 2013 and SOMS and BABS, University of NSW, Sydney, Australia
| | - M Steingruber
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University (FAU) of Erlangen-Nürnberg, Erlangen, Germany
| | - I Zeitträger
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University (FAU) of Erlangen-Nürnberg, Erlangen, Germany
| | - H Bahsi
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University (FAU) of Erlangen-Nürnberg, Erlangen, Germany
| | - N Thuma
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University (FAU) of Erlangen-Nürnberg, Erlangen, Germany
| | - Z Naing
- Serology and Virology Division, SEALS Microbiology Prince of Wales Hospital Randwick NSW 2013 and SOMS and BABS, University of NSW, Sydney, Australia
| | - Z Örfi
- Department of Molecular Biology, Max-Planck-Institute of Biochemistry, Martinsried, Germany
| | - L Örfi
- Semmelweis University, Department of Pharmaceutical Chemistry, Budapest, Hungary
| | - E Socher
- Division of Bioinformatics, Institute of Biochemistry, FAU of Erlangen-Nürnberg, Erlangen, Germany
| | - H Sticht
- Division of Bioinformatics, Institute of Biochemistry, FAU of Erlangen-Nürnberg, Erlangen, Germany
| | - W Rawlinson
- Serology and Virology Division, SEALS Microbiology Prince of Wales Hospital Randwick NSW 2013 and SOMS and BABS, University of NSW, Sydney, Australia
| | - S Chou
- Division of Infectious Diseases, Oregon Health and Science University and VA Medical Center, Portland, USA
| | - V J Haupt
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - M Marschall
- Institute of Clinical and Molecular Virology, Friedrich-Alexander University (FAU) of Erlangen-Nürnberg, Erlangen, Germany
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Kashem MA, Kennedy CA, Fogarty KE, Dimock JR, Zhang Y, Sanville-Ross ML, Skow DJ, Brunette SR, Swantek JL, Hummel HS, Swindle J, Nelson RM. A High-Throughput Genetic Complementation Assay in Yeast Cells Identified Selective Inhibitors of Sphingosine Kinase 1 Not Found Using a Cell-Free Enzyme Assay. Assay Drug Dev Technol 2016; 14:39-49. [DOI: 10.1089/adt.2015.671] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Mohammed A. Kashem
- Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | - Charles A. Kennedy
- Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | - Kylie E. Fogarty
- Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | - Janice R. Dimock
- Immunology and Respiratory Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | - Yunlong Zhang
- Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | - Mary L. Sanville-Ross
- Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | - Donna J. Skow
- Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | - Steven R. Brunette
- Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | - Jennifer L. Swantek
- Immunology and Respiratory Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
| | | | | | - Richard M. Nelson
- Small Molecule Discovery Research, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut
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Feichtinger S, Stamminger T, Müller R, Graf L, Klebl B, Eickhoff J, Marschall M. Recruitment of cyclin-dependent kinase 9 to nuclear compartments during cytomegalovirus late replication: importance of an interaction between viral pUL69 and cyclin T1. J Gen Virol 2011; 92:1519-1531. [PMID: 21450947 DOI: 10.1099/vir.0.030494-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cyclin-dependent protein kinases (CDKs) are important regulators of cellular processes and are functionally integrated into the replication of human cytomegalovirus (HCMV). Recently, a regulatory impact of CDK activity on the viral mRNA export factor pUL69 was shown. Here, specific aspects of the mode of interaction between CDK9/cyclin T1 and pUL69 are described. Intracellular localization was studied in the presence of a novel selective CDK9 inhibitor, R22, which exerts anti-cytomegaloviral activity in vitro. A pronounced R22-induced formation of nuclear speckled aggregation of pUL69 was demonstrated. Multi-labelling confocal laser-scanning microscopy revealed that CDK9 and cyclin T1 co-localized perfectly with pUL69 in individual speckles. The effects were similar to those described recently for the broad CDK inhibitor roscovitine. Co-immunoprecipitation and yeast two-hybrid analyses showed that cyclin T1 interacted with both CDK9 and pUL69. The interaction region of pUL69 for cyclin T1 could be attributed to aa 269-487. Moreover, another component of CDK inhibitor-induced speckled aggregates was identified with RNA polymerase II, supporting earlier reports that strongly suggested an association of pUL69 with transcription complexes. Interestingly, when using a UL69-deleted recombinant HCMV, no speckled aggregates were formed by CDK inhibitor treatment. This indicated that pUL69 is the defining component of aggregates and generally may represent a crucial viral interactor of cyclin T1. In conclusion, these data emphasize that HCMV inter-regulation with CDK9/cyclin T1 is at least partly based on a pUL69-cylin T1 interaction, thus contributing to the importance of CDK9 for HCMV replication.
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Affiliation(s)
- Sabine Feichtinger
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Thomas Stamminger
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Regina Müller
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Laura Graf
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
| | | | | | - Manfred Marschall
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
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The diterpenoid alkaloid noroxoaconitine is a Mapkap kinase 5 (MK5/PRAK) inhibitor. Cell Mol Life Sci 2010; 68:289-301. [PMID: 20640477 PMCID: PMC3016492 DOI: 10.1007/s00018-010-0452-1] [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: 03/23/2010] [Revised: 06/25/2010] [Accepted: 07/01/2010] [Indexed: 12/19/2022]
Abstract
The mitogen-activated protein kinase-activated protein kinase MK5 is ubiquitously expressed in vertebrates and is implicated in cell proliferation, cytoskeletal remodeling, and anxiety behavior. This makes MK5 an attractive drug target. We tested several diterpenoid alkaloids for their ability to suppress MK5 kinase activity. We identified noroxoaconitine as an ATP competitor that inhibited the catalytic activity of MK5 in vitro (IC50 = 37.5 μM; Ki = 0.675 μM) and prevented PKA-induced nuclear export of MK5, a process that depends on kinase active MK5. MK5 is closely related to MK2 and MK3, and noroxoaconitine inhibited MK3- and MK5- but not MK2-mediated phosphorylation of the common substrate Hsp27. Molecular docking of noroxoaconitine into the ATP binding sites indicated that noroxoaconitine binds more strongly to MK5 than to MK3. Noroxoaconitine and derivatives may help in elucidating the precise biological functions of MK5 and may prove to have therapeutic values.
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Mercorelli B, Sinigalia E, Loregian A, Palù G. Human cytomegalovirus DNA replication: antiviral targets and drugs. Rev Med Virol 2008; 18:177-210. [PMID: 18027349 DOI: 10.1002/rmv.558] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Human cytomegalovirus (HCMV) infection is associated with severe morbidity and mortality in immunocompromised individuals, in particular transplant recipients and AIDS patients, and is the most frequent congenital viral infection in humans. There are currently five drugs approved for HCMV treatment: ganciclovir and its prodrug valganciclovir, foscarnet, cidofovir and fomivirsen. These drugs have provided a major advance in HCMV disease management, but they suffer from poor bioavailability, significant toxicity and limited effectiveness, mainly due to the development of drug resistance. Fortunately, there are several novel and potentially very effective new compounds which are under pre-clinical and clinical evaluation and may address these limitations. This review focuses on HCMV proteins that are directly or indirectly involved in viral DNA replication and represent already established or potential novel antiviral targets, and describes both currently available drugs and new compounds against such protein targets.
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Affiliation(s)
- Beatrice Mercorelli
- Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, 35121 Padua, Italy
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Schleiss M, Eickhoff J, Auerochs S, Leis M, Abele S, Rechter S, Choi Y, Anderson J, Scott G, Rawlinson W, Michel D, Ensminger S, Klebl B, Stamminger T, Marschall M. Protein kinase inhibitors of the quinazoline class exert anti-cytomegaloviral activity in vitro and in vivo. Antiviral Res 2008; 79:49-61. [PMID: 18329738 DOI: 10.1016/j.antiviral.2008.01.154] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 01/17/2008] [Accepted: 01/23/2008] [Indexed: 11/17/2022]
Abstract
Cytomegalovirus infection is associated with severe disease in immunocompromised individuals. Current antiviral therapy faces several limitations. In a search of novel drug candidates, we describe here the anti-cytomegaloviral properties of two compounds of the chemical class of quinazolines, gefitinib (Iressa) and Ax7396 (RGB-315389). Both compounds showed strong inhibitory effects in vitro against human and animal cytomegaloviruses with IC(50)s in a low micromolar range. Cytotoxicity did not occur at these effective concentrations. The antiviral mode of action was based on the inhibition of protein kinase activity, mainly directed to a viral target kinase (UL97/M97) in addition to cellular target candidates. This was demonstrated by a high sensitivity of the respective protein kinases in vitro and by infection experiments with viral mutants carrying genomic alterations in the ORF UL97/M97 modulating viral drug sensitivity. In a guinea pig model, gefitinib showed inhibition of cytomegaloviral loads in blood and lung tissue. Importantly, the rate of mortality of infected animals was reduced by gefitinib treatment. In contrast to the in vitro data, Ax7396 showed no significant antiviral activity in a mouse model. Further in vivo analyses have to assess the potential use of gefitinib in the treatment of cytomegalovirus disease.
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Affiliation(s)
- Mark Schleiss
- Center for Infectious Diseases and Microbiology Translational Research, Department of Pediatrics, University of Minnesota, Minneapolis, MN, USA
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Gershburg E, Pagano JS. Conserved herpesvirus protein kinases. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1784:203-12. [PMID: 17881303 PMCID: PMC2265104 DOI: 10.1016/j.bbapap.2007.08.009] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Revised: 08/08/2007] [Accepted: 08/09/2007] [Indexed: 11/21/2022]
Abstract
Conserved herpesviral protein kinases (CHPKs) are a group of enzymes conserved throughout all subfamilies of Herpesviridae. Members of this group are serine/threonine protein kinases that are likely to play a conserved role in viral infection by interacting with common host cellular and viral factors; however, along with a conserved role, individual kinases may have unique functions in the context of viral infection in such a way that they are only partially replaceable even by close homologues. Recent studies demonstrated that CHPKs are crucial for viral infection and suggested their involvement in regulation of numerous processes at various infection steps (primary infection, nuclear egress, tegumentation), although the mechanisms of this regulation remain unknown. Notwithstanding, recent advances in discovery of new CHPK targets, and studies of CHPK knockout phenotypes have raised their attractiveness as targets for antiviral therapy. A number of compounds have been shown to inhibit the activity of human cytomegalovirus (HCMV)-encoded UL97 protein kinase and exhibit a pronounced antiviral effect, although the same compounds are inactive against Epstein-Barr virus (EBV)-encoded protein kinase BGLF4, illustrating the fact that low homology between the members of this group complicates development of compounds targeting the whole group, and suggesting that individualized, structure-based inhibitor design will be more effective. Determination of CHPK structures will greatly facilitate this task.
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Affiliation(s)
- Edward Gershburg
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Abstract
The Predictive ADME-Tox conference brought together scientists responsible for innovative in vitro and in silico screens to predict particular chemical liabilities. Oral bioavailability without adverse effects requires good absorption, distribution, metabolism and excretion (ADME) and minimal toxicity. Traditionally, these properties are measured late in development, when sufficient material is available for classical assays. Although these assays remain the gold standard, the conference focused on novel methods to predict liabilities early in the development pipeline, when a course change has less impact in the development timeline. Emerging themes from the meeting were i) integration - of data from a number of predictive assays into a 'profile' of a new class, and of safety scientists into discovery teams, in order to guide interpretation of the profile and identify tests to include in the hit-to-lead process; and ii) collaboration. As in silico predictive models are increasingly accepted, from reactivity and genetic toxicity to models for hERG inhibition, kinase crossreactivity and cytochrome P450 reactivity, increasing amounts of high-quality data will be needed to 'feed' the models. Such data will soon be beyond the capabilities of individual organisations to generate, and methods for pooling data are needed to advance the generation of predictive models for new toxicities. In addition, collaboration to apply novel methods such as metabonomics profiling to withdrawn drugs may permit the identification of new safety biomarkers to prevent such costly failures.
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Affiliation(s)
- Jennifer Fostel
- US National Center for Toxicogenomics, National Institute for Environmental Health Sciences, Lockheed Martin Information Technology, Research Triangle Park, North Carolina, USA.
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Herget T, Freitag M, Morbitzer M, Kupfer R, Stamminger T, Marschall M. Novel chemical class of pUL97 protein kinase-specific inhibitors with strong anticytomegaloviral activity. Antimicrob Agents Chemother 2004; 48:4154-62. [PMID: 15504835 PMCID: PMC525407 DOI: 10.1128/aac.48.11.4154-4162.2004] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a major human pathogen frequently associated with life-threatening disease in immunosuppressed patients and newborns. The HCMV UL97-encoded protein kinase (pUL97) represents an important determinant of viral replication. Recent studies demonstrated that pUL97-specific kinase inhibitors are powerful tools for the control of HCMV replication. We present evidence that three related quinazoline compounds are potent inhibitors of the pUL97 kinase activity and block in vitro substrate phosphorylation, with 50% inhibitory concentrations (IC(50)s) between 30 and 170 nM. Replication of HCMV in primary human fibroblasts was suppressed with a high efficiency. The IC(50)s of these three quinazoline compounds (2.4 +/- 0.4, 3.4 +/- 0.6, and 3.9 +/- 1.1 microM, respectively) were in the range of the IC(50) of ganciclovir (1.2 +/- 0.2 microM), as determined by the HCMV green fluorescent protein-based antiviral assay. Importantly, the quinazolines were demonstrated to have strong inhibitory effects against clinical HCMV isolates, including ganciclovir- and cidofovir-resistant virus variants. Moreover, in contrast to ganciclovir, the formation of resistance to the quinazolines was not observed. The mechanisms of action of these compounds were confirmed by kinetic analyses with infected cells. Quinazolines specifically inhibited viral early-late protein synthesis but had no effects at other stages of the replication cycle, such as viral entry, consistent with a blockage of the pUL97 function. In contrast to epithelial growth factor receptor inhibitors, quinazolines affected HCMV replication even when they were added hours after virus adsorption. Thus, our findings indicate that quinazolines are highly efficient inhibitors of HCMV replication in vitro by targeting pUL97 protein kinase activity.
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Affiliation(s)
- Thomas Herget
- Institute for Clinical and Molecular Virology, University of Erlangen-Nürnberg, Erlangen 91054, Germany.
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