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Delfing B, Laracuente XE, Jeffries W, Luo X, Olson A, Foreman KW, Petruncio G, Lee KH, Paige M, Kehn-Hall K, Lockhart C, Klimov DK. Competitive Binding of Viral Nuclear Localization Signal Peptide and Inhibitor Ligands to Importin-α Nuclear Transport Protein. J Chem Inf Model 2024; 64:5262-5272. [PMID: 38869471 PMCID: PMC11234363 DOI: 10.1021/acs.jcim.4c00626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/14/2024]
Abstract
Venezuelan equine encephalitis virus (VEEV) is a highly virulent pathogen whose nuclear localization signal (NLS) sequence from capsid protein binds to the host importin-α transport protein and blocks nuclear import. We studied the molecular mechanisms by which two small ligands, termed I1 and I2, interfere with the binding of VEEV's NLS peptide to importin-α protein. To this end, we performed all-atom replica exchange molecular dynamics simulations probing the competitive binding of the VEEV coreNLS peptide and I1 or I2 ligand to the importin-α major NLS binding site. As a reference, we used our previous simulations, which examined noncompetitive binding of the coreNLS peptide or the inhibitors to importin-α. We found that both inhibitors completely abrogate the native binding of the coreNLS peptide, forcing it to adopt a manifold of nonnative loosely bound poses within the importin-α major NLS binding site. Both inhibitors primarily destabilize the native coreNLS binding by masking its amino acids rather than competing with it for binding to importin-α. Because I2, in contrast to I1, binds off-site localizing on the edge of the major NLS binding site, it inhibits fewer coreNLS native binding interactions than I1. Structural analysis is supported by computations of the free energies of the coreNLS peptide binding to importin-α with or without competition from the inhibitors. Specifically, both inhibitors reduce the free energy gain from coreNLS binding, with I1 causing significantly larger loss than I2. To test our simulations, we performed AlphaScreen experiments measuring IC50 values for both inhibitors. Consistent with in silico results, the IC50 value for I1 was found to be lower than that for I2. We hypothesize that the inhibitory action of I1 and I2 ligands might be specific to the NLS from VEEV's capsid protein.
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Affiliation(s)
- Bryan
M. Delfing
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Xavier E. Laracuente
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - William Jeffries
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Xingyu Luo
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Audrey Olson
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Kenneth W. Foreman
- Department
of Chemistry and Biochemistry, George Mason
University, Fairfax, Virginia 22030, United States
| | - Greg Petruncio
- Department
of Chemistry and Biochemistry, George Mason
University, Fairfax, Virginia 22030, United States
- Center
for Molecular Engineering, George Mason
University, Manassas, Virginia 20110, United States
| | - Kyung Hyeon Lee
- Department
of Chemistry and Biochemistry, George Mason
University, Fairfax, Virginia 22030, United States
- Center
for Molecular Engineering, George Mason
University, Manassas, Virginia 20110, United States
| | - Mikell Paige
- Department
of Chemistry and Biochemistry, George Mason
University, Fairfax, Virginia 22030, United States
- Center
for Molecular Engineering, George Mason
University, Manassas, Virginia 20110, United States
| | - Kylene Kehn-Hall
- Department
of Biomedical Sciences and Pathobiology, Virginia-Maryland College
of Veterinary Medicine, Virginia Polytechnic
Institute and State University, Blacksburg, Virginia 24061, United States
- Center
for Emerging, Zoonotic, and Arthropod-Borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
| | - Christopher Lockhart
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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Xu X, Gao S, Zuo Q, Gong J, Song X, Liu Y, Xiao J, Zhai X, Sun H, Zhang M, Gao X, Guo D. Enhanced In Vitro Antiviral Activity of Ivermectin-Loaded Nanostructured Lipid Carriers against Porcine Epidemic Diarrhea Virus via Improved Intracellular Delivery. Pharmaceutics 2024; 16:601. [PMID: 38794264 PMCID: PMC11125651 DOI: 10.3390/pharmaceutics16050601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 04/18/2024] [Accepted: 04/25/2024] [Indexed: 05/26/2024] Open
Abstract
Porcine epidemic diarrhea virus (PEDV) is an acute enteric coronavirus, inducing watery diarrhea and high mortality in piglets, leading to huge economic losses in global pig industry. Ivermectin (IVM), an FDA-approved antiparasitic agent, is characterized by high efficacy and wide applicability. However, the poor bioavailability limits its application. Since the virus is parasitized inside the host cells, increasing the intracellular drug uptake can improve antiviral efficacy. Hence, we aimed to develop nanostructured lipid carriers (NLCs) to enhance the antiviral efficacy of IVM. The findings first revealed the capacity of IVM to inhibit the infectivity of PEDV by reducing viral replication with a certain direct inactivation effect. The as-prepared IVM-NLCs possessed hydrodynamic diameter of 153.5 nm with a zeta potential of -31.5 mV and high encapsulation efficiency (95.72%) and drug loading (11.17%). IVM interacted with lipids and was enveloped in lipid carriers with an amorphous state. Furthermore, its encapsulation in NLCs could enhance drug internalization. Meanwhile, IVM-NLCs inhibited PEDV proliferation by up to three orders of magnitude in terms of viral RNA copies, impeding the accumulation of reactive oxygen species and mitigating the mitochondrial dysfunction caused by PEDV infection. Moreover, IVM-NLCs markedly decreased the apoptosis rate of PEDV-induced Vero cells. Hence, IVM-NLCs showed superior inhibitory effect against PEDV compared to free IVM. Together, these results implied that NLCs is an efficient delivery system for IVM to improve its antiviral efficacy against PEDV via enhanced intracellular uptake.
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Affiliation(s)
- Xiaolin Xu
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Shasha Gao
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Qindan Zuo
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Jiahao Gong
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Xinhao Song
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Yongshi Liu
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Jing Xiao
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Xiaofeng Zhai
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
- Academy for Advanced Interdisciplinary Studies, Nanjing Agricultural University, Nanjing 210095, China
| | - Haifeng Sun
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Mingzhi Zhang
- Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Xiuge Gao
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Dawei Guo
- Engineering Center of Innovative Veterinary Drugs, Center for Veterinary Drug Research and Evaluation, MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
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Delfing BM, Laracuente XE, Olson A, Foreman KW, Paige M, Kehn-Hall K, Lockhart C, Klimov DK. Binding of viral nuclear localization signal peptides to importin-α nuclear transport protein. Biophys J 2023; 122:3476-3488. [PMID: 37542371 PMCID: PMC10502480 DOI: 10.1016/j.bpj.2023.07.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/23/2023] [Accepted: 07/27/2023] [Indexed: 08/06/2023] Open
Abstract
Using all-atom replica-exchange molecular dynamics simulations, we mapped the mechanisms of binding of the nuclear localization signal (NLS) sequence from Venezuelan equine encephalitis virus (VEEV) capsid protein to importin-α (impα) transport protein. Our objective was to identify the VEEV NLS sequence fragment that confers native, experimentally resolved binding to impα as well as to study associated binding energetics and conformational ensembles. The two selected VEEV NLS peptide fragments, KKPK and KKPKKE, show strikingly different binding mechanisms. The minNLS peptide KKPK binds non-natively and nonspecifically by adopting five diverse conformational clusters with low similarity to the x-ray structure 3VE6 of NLS-impα complex. Despite the prevalence of non-native interactions, the minNLS peptide still largely binds to the impα major NLS binding site. In contrast, the coreNLS peptide KKPKKE binds specifically and natively, adopting a largely homogeneous binding ensemble with a dominant, highly native-like conformational cluster. The coreNLS peptide retains most of native binding interactions, including π-cation contacts and a tryptophan cage. While KKPK binding is governed by a complex multistate free energy landscape featuring transitions between multiple binding poses, the coreNLS peptide free energy map is simple, exhibiting a single dominant native-like bound basin. We argue that the origin of the coreNLS peptide binding specificity is several electrostatic interactions formed by the two C-terminal amino acids, Lys10 and Glu11, with impα. The coreNLS sequence is then sufficient for native binding, but none of the amino acids flanking minNLS, including Lys10 and Glu11, are strictly necessary for the native pose. Our analyses indicate that the VEEV coreNLS sequence is virtually unique among human and viral proteins interacting with impα making it a potential target for VEEV-specific inhibitors.
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Affiliation(s)
- Bryan M Delfing
- School of Systems Biology, George Mason University, Manassas, Virginia
| | | | - Audrey Olson
- School of Systems Biology, George Mason University, Manassas, Virginia
| | - Kenneth W Foreman
- Department of Chemistry and Biochemistry, George Mason University, Manassas, Virginia
| | - Mikell Paige
- Department of Chemistry and Biochemistry, George Mason University, Manassas, Virginia
| | - Kylene Kehn-Hall
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia; Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | | | - Dmitri K Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia.
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Lockhart C, Luo X, Olson A, Delfing BM, Laracuente XE, Foreman KW, Paige M, Kehn-Hall K, Klimov DK. Can Free Energy Perturbation Simulations Coupled with Replica-Exchange Molecular Dynamics Study Ligands with Distributed Binding Sites? J Chem Inf Model 2023; 63:4791-4802. [PMID: 37531558 PMCID: PMC10947611 DOI: 10.1021/acs.jcim.3c00631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
Free energy perturbation coupled with replica exchange with solute tempering (FEP/REST) offers a rigorous approach to compute relative free energy changes for ligands. To determine the applicability of FEP/REST for the ligands with distributed binding poses, we considered two alchemical transformations involving three putative inhibitors I0, I1, and I2 of the Venezuelan equine encephalitis virus nuclear localization signal sequence binding to the importin-α (impα) transporter protein. I0 → I1 and I0 → I2 transformations, respectively, increase or decrease the polarity of the parent molecule. Our objective was three-fold─(i) to verify FEP/REST technical performance and convergence, (ii) to estimate changes in binding free energy ΔΔG, and (iii) to determine the utility of FEP/REST simulations for conformational binding analysis. Our results are as follows. First, our FEP/REST implementation properly follows FEP/REST formalism and produces converged ΔΔG estimates. Due to ligand inherent unbinding, the better FEP/REST strategy lies in performing multiple independent trajectories rather than extending their length. Second, I0 → I1 and I0 → I2 transformations result in overall minor changes in inhibitor binding free energy, slightly strengthening the affinity of I1 and weakening that of I2. Electrostatic interactions dominate binding interactions, determining the enthalpic changes. The two transformations cause opposite entropic changes, which ultimately govern binding affinities. Importantly, we confirm the validity of FEP/REST free energy estimates by comparing them with our previous REST simulations, directly probing binding of three ligands to impα. Third, we established that FEP/REST simulations can sample binding ensembles of ligands. Thus, FEP/REST can be applied (i) to study the energetics of the ligand binding without defined poses and showing minor differences in affinities |ΔΔG| ≲ 0.5 kcal/mol and (ii) to collect ligand binding conformational ensembles.
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Affiliation(s)
| | - Xingyu Luo
- School of Systems Biology, George Mason University, Manassas, VA 20110
| | - Audrey Olson
- School of Systems Biology, George Mason University, Manassas, VA 20110
| | - Bryan M. Delfing
- School of Systems Biology, George Mason University, Manassas, VA 20110
| | | | - Kenneth W. Foreman
- Department of Chemistry and Biochemistry, George Mason University, Fairfax, VA 22030
| | - Mikell Paige
- Department of Chemistry and Biochemistry, George Mason University, Fairfax, VA 22030
| | - Kylene Kehn-Hall
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061
| | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, VA 20110
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5
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Bhambid M, Dey V, Walunj S, Patankar S. Toxoplasma Gondii Importin α Shows Weak Auto-Inhibition. Protein J 2023:10.1007/s10930-023-10128-2. [PMID: 37284905 DOI: 10.1007/s10930-023-10128-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2023] [Indexed: 06/08/2023]
Abstract
Importin α is a nuclear transporter that binds to nuclear localization signals (NLSs), consisting of 7-20 positively charged amino acids found within cargo proteins. In addition to cargo binding, intramolecular interactions also occur within the importin α protein due to binding between the importin β-binding (IBB) domain and the NLS-binding sites, a phenomenon called auto-inhibition. The interactions causing auto-inhibition are driven by a stretch of basic residues, similar to an NLS, in the IBB domain. Consistent with this, importin α proteins that do not have some of these basic residues lack auto-inhibition; a naturally occurring example of such a protein is found in the apicomplexan parasite Plasmodium falciparum. In this report, we show that importin α from another apicomplexan parasite, Toxoplasma gondii, harbors basic residues (KKR) in the IBB domain and exhibits auto-inhibition. This protein has a long, unstructured hinge motif (between the IBB domain and the NLS-binding sites) that does not contribute to auto-inhibition. However, the IBB domain may have a higher propensity to form an α-helical structure, positioning the wild-type KKR motif in an orientation that results in weaker interactions with the NLS-binding site than a KRR mutant. We conclude that the importin α protein from T. gondii shows auto-inhibition, exhibiting a different phenotype from that of P. falciparum importin α. However, our data indicate that T. gondii importin α may have a low strength of auto-inhibition. We hypothesize that low levels of auto-inhibition may confer an advantage to these important human pathogens.
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Affiliation(s)
- Manasi Bhambid
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Vishakha Dey
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
- Indiana University School of Medicine, Indianapolis, USA
| | - Sujata Walunj
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
- IITB-Monash Research Academy, IIT Bombay, Mumbai, India
| | - Swati Patankar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India.
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6
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Del ng BM, Olson A, Laracuente XE, Foreman KW, Paige M, Kehn-Hall K, Lockhart C, Klimov DK. Binding of Venezuelan Equine Encephalitis Virus Inhibitors to Importin-α Receptors Explored with All-Atom Replica Exchange Molecular Dynamics. J Phys Chem B 2023; 127:3175-3186. [PMID: 37001021 PMCID: PMC10358320 DOI: 10.1021/acs.jpcb.3c00429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
Abstract
Although Venezuelan equine encephalitis virus (VEEV) is a life-threatening pathogen with a capacity for epidemic outbreaks, there are no FDA-approved VEEV antivirals for humans. VEEV cytotoxicity is partially attributed to the formation of a tetrameric complex between the VEEV capsid protein, the nuclear import proteins importin-α and importin-β, and the nuclear export protein CRM1, which together block trafficking through the nuclear pore complex. Experimental studies have identified small molecules from the CL6662 scaffold as potential inhibitors of the viral nuclear localization signal (NLS) sequence binding to importin-α. However, little is known about the molecular mechanism of CL6662 inhibition. To address this issue, we employed all-atom replica exchange molecular dynamics simulations to probe, in atomistic detail, the binding mechanism of CL6662 ligands to importin-α. Three ligands, including G281-1485 and two congeners with varying hydrophobicities, were considered. We investigated the distribution of ligand binding poses, their locations, and ligand specificities measured by the strength of binding interactions. We found that G281-1485 binds nonspecifically without forming well-defined binding poses throughout the NLS binding site. Binding of the less hydrophobic congener becomes strongly on-target with respect to the NLS binding site but remains nonspecific. However, a more hydrophobic congener is a strongly specific binder and the only ligand out of three to form a well-defined binding pose, while partially overlapping with the NLS binding site. On the basis of free energy estimates, we argue that all three ligands weakly compete with the viral NLS sequence for binding to importin-α in an apparent compromise to preserve host NLS binding. We further show that all-atom replica exchange binding simulations are a viable tool for studying ligands binding nonspecifically without forming well-defined binding poses.
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Affiliation(s)
- Bryan M. Del ng
- School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Audrey Olson
- School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | | | - Kenneth W. Foreman
- Department of Chemistry and Biochemistry, George Mason University, Manassas, VA 20110, USA
| | - Mikell Paige
- Department of Chemistry and Biochemistry, George Mason University, Manassas, VA 20110, USA
| | - Kylene Kehn-Hall
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | | | - Dmitri K. Klimov
- School of Systems Biology, George Mason University, Manassas, VA 20110, USA
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Boghdeh NA, McGraw B, Barrera MD, Anderson C, Baha H, Risner KH, Ogungbe IV, Alem F, Narayanan A. Inhibitors of the Ubiquitin-Mediated Signaling Pathway Exhibit Broad-Spectrum Antiviral Activities against New World Alphaviruses. Viruses 2023; 15:v15030655. [PMID: 36992362 PMCID: PMC10059822 DOI: 10.3390/v15030655] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 02/09/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
New World alphaviruses including Venezuelan Equine Encephalitis Virus (VEEV) and Eastern Equine Encephalitis Virus (EEEV) are mosquito-transmitted viruses that cause disease in humans and equines. There are currently no FDA-approved therapeutics or vaccines to treat or prevent exposure-associated encephalitic disease. The ubiquitin proteasome system (UPS)-associated signaling events are known to play an important role in the establishment of a productive infection for several acutely infectious viruses. The critical engagement of the UPS-associated signaling mechanisms by many viruses as host–pathogen interaction hubs led us to hypothesize that small molecule inhibitors that interfere with these signaling pathways will exert broad-spectrum inhibitory activity against alphaviruses. We queried eight inhibitors of the UPS signaling pathway for antiviral outcomes against VEEV. Three of the tested inhibitors, namely NSC697923 (NSC), bardoxolone methyl (BARM) and omaveloxolone (OMA) demonstrated broad-spectrum antiviral activity against VEEV and EEEV. Dose dependency and time of addition studies suggest that BARM and OMA exhibit intracellular and post-entry viral inhibition. Cumulatively, our studies indicate that inhibitors of the UPS-associated signaling pathways exert broad-spectrum antiviral outcomes in the context of VEEV and EEEV infection, supporting their translational application as therapeutic candidates to treat alphavirus infections.
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Affiliation(s)
- Niloufar A. Boghdeh
- Biomedical Research Laboratory, George Mason University, Manassas, VA 20110, USA
| | - Brittany McGraw
- School of Systems Biology, College of Science, George Mason University, Manassas, VA 20110, USA
| | - Michael D. Barrera
- Biomedical Research Laboratory, George Mason University, Manassas, VA 20110, USA
- School of Systems Biology, College of Science, George Mason University, Manassas, VA 20110, USA
| | - Carol Anderson
- Biomedical Research Laboratory, George Mason University, Manassas, VA 20110, USA
- School of Systems Biology, College of Science, George Mason University, Manassas, VA 20110, USA
| | - Haseebullah Baha
- Biomedical Research Laboratory, George Mason University, Manassas, VA 20110, USA
- School of Systems Biology, College of Science, George Mason University, Manassas, VA 20110, USA
| | - Kenneth H. Risner
- Biomedical Research Laboratory, George Mason University, Manassas, VA 20110, USA
- School of Systems Biology, College of Science, George Mason University, Manassas, VA 20110, USA
| | - Ifedayo V. Ogungbe
- Department of Chemistry, Physics and Atmospheric Sciences, Jackson State University, Jackson, MS 39217, USA
| | - Farhang Alem
- Biomedical Research Laboratory, George Mason University, Manassas, VA 20110, USA
- School of Systems Biology, College of Science, George Mason University, Manassas, VA 20110, USA
| | - Aarthi Narayanan
- Biomedical Research Laboratory, George Mason University, Manassas, VA 20110, USA
- Department of Biology, College of Science, George Mason University, Fairfax, VA 22030, USA
- Correspondence:
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Ogorek TJ, Golden JE. Advances in the Development of Small Molecule Antivirals against Equine Encephalitic Viruses. Viruses 2023; 15:413. [PMID: 36851628 PMCID: PMC9958955 DOI: 10.3390/v15020413] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/29/2023] [Accepted: 01/30/2023] [Indexed: 02/04/2023] Open
Abstract
Venezuelan, western, and eastern equine encephalitic alphaviruses (VEEV, WEEV, and EEEV, respectively) are arboviruses that are highly pathogenic to equines and cause significant harm to infected humans. Currently, human alphavirus infection and the resulting diseases caused by them are unmitigated due to the absence of approved vaccines or therapeutics for general use. These circumstances, combined with the unpredictability of outbreaks-as exemplified by a 2019 EEE surge in the United States that claimed 19 patient lives-emphasize the risks posed by these viruses, especially for aerosolized VEEV and EEEV which are potential biothreats. Herein, small molecule inhibitors of VEEV, WEEV, and EEEV are reviewed that have been identified or advanced in the last five years since a comprehensive review was last performed. We organize structures according to host- versus virus-targeted mechanisms, highlight cellular and animal data that are milestones in the development pipeline, and provide a perspective on key considerations for the progression of compounds at early and later stages of advancement.
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Affiliation(s)
- Tyler J. Ogorek
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jennifer E. Golden
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, USA
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Kehn-Hall K, Bradfute SB. Understanding host responses to equine encephalitis virus infection: implications for therapeutic development. Expert Rev Anti Infect Ther 2022; 20:1551-1566. [PMID: 36305549 DOI: 10.1080/14787210.2022.2141224] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Venezuelan, eastern, and western equine encephalitis viruses (VEEV, EEEV, and WEEV) are mosquito-borne New World alphaviruses that cause encephalitis in equids and humans. These viruses can cause severe disease and death, as well as long-term severe neurological symptoms in survivors. Despite the pathogenesis and weaponization of these viruses, there are no approved therapeutics for treating infection. AREAS COVERED In this review, we describe the molecular pathogenesis of these viruses, discuss host-pathogen interactions needed for viral replication, and highlight new avenues for drug development with a focus on host-targeted approaches. EXPERT OPINION Current approaches have yielded some promising therapeutics, but additional emphasis should be placed on advanced development of existing small molecules and pursuit of pan-encephalitic alphavirus drugs. More research should be conducted on EEEV and WEEV, given their high lethality rates.
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Affiliation(s)
- Kylene Kehn-Hall
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA.,Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Tech, Blacksburg, VA, USA
| | - Steven B Bradfute
- Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
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Walunj SB, Wang C, Wagstaff KM, Patankar S, Jans DA. Conservation of Importin α Function in Apicomplexans: Ivermectin and GW5074 Target Plasmodium falciparum Importin α and Inhibit Parasite Growth in Culture. Int J Mol Sci 2022; 23:ijms232213899. [PMID: 36430384 PMCID: PMC9695642 DOI: 10.3390/ijms232213899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/03/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
Abstract
Signal-dependent transport into and out of the nucleus mediated by members of the importin (IMP) superfamily of nuclear transporters is critical to the eukaryotic function and a point of therapeutic intervention with the potential to limit disease progression and pathogenic outcomes. Although the apicomplexan parasites Plasmodium falciparum and Toxoplasma gondii both retain unique IMPα genes that are essential, a detailed analysis of their properties has not been performed. As a first step to validate apicomplexan IMPα as a target, we set out to compare the properties of P. falciparum and T. gondii IMPα (PfIMPα and TgIMPα, respectively) to those of mammalian IMPα, as exemplified by Mus musculus IMPα (MmIMPα). Close similarities were evident, with all three showing high-affinity binding to modular nuclear localisation signals (NLSs) from apicomplexans as well as Simian virus SV40 large tumour antigen (T-ag). PfIMPα and TgIMPα were also capable of binding to mammalian IMPβ1 (MmIMPβ1) with high affinity; strikingly, NLS binding by PfIMPα and TgIMPα could be inhibited by the mammalian IMPα targeting small molecules ivermectin and GW5074 through direct binding to PfIMPα and TgIMPα to perturb the α-helical structure. Importantly, GW5074 could be shown for the first time to resemble ivermectin in being able to limit growth of P. falciparum. The results confirm apicomplexan IMPα as a viable target for the development of therapeutics, with agents targeting it worthy of further consideration as an antimalarial.
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Affiliation(s)
- Sujata B. Walunj
- Molecular Parasitology Lab., Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
- Nuclear Signalling Lab., Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia
| | - Chunxiao Wang
- Nuclear Signalling Lab., Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia
| | - Kylie M. Wagstaff
- Nuclear Signalling Lab., Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia
| | - Swati Patankar
- Molecular Parasitology Lab., Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - David A. Jans
- Nuclear Signalling Lab., Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia
- Correspondence:
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11
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High-Throughput Screening to Identify Inhibitors of Plasmodium falciparum Importin α. Cells 2022; 11:cells11071201. [PMID: 35406765 PMCID: PMC8997399 DOI: 10.3390/cells11071201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 03/25/2022] [Accepted: 03/29/2022] [Indexed: 11/16/2022] Open
Abstract
The global burden of malaria and toxoplasmosis has been limited by the use of efficacious anti-parasitic agents, however, emerging resistance in Plasmodium species and Toxoplasma gondii threatens disease control worldwide, implying that new agents/therapeutic targets are urgently needed. Nuclear localization signal (NLS)-dependent transport into the nucleus, mediated by members of the importin (IMP) superfamily of nuclear transporters, has shown potential as a target for intervention to limit viral infection. Here, we show for the first time that IMPα from P. falciparum and T. gondii have promise as targets for small molecule inhibitors. We use high-throughput screening to identify agents able to inhibit P. falciparum IMPα binding to a P. falciparum NLS, identifying a number of compounds that inhibit binding in the µM-nM range, through direct binding to P. falciparum IMPα, as shown in thermostability assays. Of these, BAY 11-7085 is shown to be a specific inhibitor of P. falciparum IMPα-NLS recognition. Importantly, a number of the inhibitors limited growth by both P. falciparum and T. gondii. The results strengthen the hypothesis that apicomplexan IMPα proteins have potential as therapeutic targets to aid in identifying novel agents for two important, yet neglected, parasitic diseases.
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12
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Yang SNY, Maher B, Wang C, Wagstaff KM, Fraser JE, Jans DA. High Throughput Screening Targeting the Dengue NS3-NS5 Interface Identifies Antivirals against Dengue, Zika and West Nile Viruses. Cells 2022; 11:730. [PMID: 35203378 PMCID: PMC8870125 DOI: 10.3390/cells11040730] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/03/2022] [Accepted: 02/11/2022] [Indexed: 12/04/2022] Open
Abstract
Dengue virus (DENV) threatens almost 70% of the world's population, with no effective therapeutic currently available and controversy surrounding the one approved vaccine. A key factor in dengue viral replication is the interaction between DENV nonstructural proteins (NS) 5 and 3 (NS3) in the infected cell. Here, we perform a proof-of-principle high-throughput screen to identify compounds targeting the NS5-NS3 binding interface. We use a range of approaches to show for the first time that two small molecules-repurposed drugs I-OMe tyrphostin AG538 (I-OMe-AG238) and suramin hexasodium (SHS)-inhibit NS5-NS3 binding at low μM concentration through direct binding to NS5 that impacts thermostability. Importantly, both have strong antiviral activity at low μM concentrations against not only DENV-2, but also Zika virus (ZIKV) and West Nile virus (WNV). This work highlights the NS5-NS3 binding interface as a viable target for the development of anti-flaviviral therapeutics.
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Affiliation(s)
| | | | | | | | | | - David A. Jans
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Monash, VIC 3800, Australia; (S.N.Y.Y.); (B.M.); (C.W.); (K.M.W.); (J.E.F.)
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13
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Martin AJ, Jans DA. Antivirals that target the host IMPα/β1-virus interface. Biochem Soc Trans 2021; 49:281-295. [PMID: 33439253 PMCID: PMC7925013 DOI: 10.1042/bst20200568] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 12/22/2022]
Abstract
Although transport into the nucleus mediated by the importin (IMP) α/β1-heterodimer is central to viral infection, small molecule inhibitors of IMPα/β1-dependent nuclear import have only been described and shown to have antiviral activity in the last decade. Their robust antiviral activity is due to the strong reliance of many different viruses, including RNA viruses such as human immunodeficiency virus-1 (HIV-1), dengue (DENV), and Zika (ZIKV), on the IMPα/β1-virus interface. High-throughput compound screens have identified many agents that specifically target this interface. Of these, agents targeting IMPα/β1 directly include the FDA-approved macrocyclic lactone ivermectin, which has documented broad-spectrum activity against a whole range of viruses, including HIV-1, DENV1-4, ZIKV, West Nile virus (WNV), Venezuelan equine encephalitis virus, chikungunya, and most recently, SARS-CoV-2 (COVID-19). Ivermectin has thus far been tested in Phase III human clinical trials for DENV, while there are currently close to 80 trials in progress worldwide for SARS-CoV-2; preliminary results for randomised clinical trials (RCTs) as well as observational/retrospective studies are consistent with ivermectin affording clinical benefit. Agents that target the viral component of the IMPα/β1-virus interface include N-(4-hydroxyphenyl) retinamide (4-HPR), which specifically targets DENV/ZIKV/WNV non-structural protein 5 (NS5). 4-HPR has been shown to be a potent inhibitor of infection by DENV1-4, including in an antibody-dependent enhanced animal challenge model, as well as ZIKV, with Phase II clinical challenge trials planned. The results from rigorous RCTs will help determine the therapeutic potential of the IMPα/β1-virus interface as a target for antiviral development.
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Affiliation(s)
- Alexander J. Martin
- Nuclear Signaling Lab., Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Australia
| | - David A. Jans
- Nuclear Signaling Lab., Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Australia
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14
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Jans DA, Wagstaff KM. The broad spectrum host-directed agent ivermectin as an antiviral for SARS-CoV-2 ? Biochem Biophys Res Commun 2021; 538:163-172. [PMID: 33341233 PMCID: PMC7577703 DOI: 10.1016/j.bbrc.2020.10.042] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 10/18/2020] [Indexed: 12/16/2022]
Abstract
FDA approved for parasitic indications, the small molecule ivermectin has been the focus of growing attention in the last 8 years due to its potential as an antiviral. We first identified ivermectin in a high throughput compound library screen as an agent potently able to inhibit recognition of the nuclear localizing Human Immunodeficiency Virus-1 (HIV-1) integrase protein by the host importin (IMP) α/β1 heterodimer, and recently demonstrated its ability to bind directly to IMPα to cause conformational changes that prevent its function in nuclear import of key viral as well as host proteins. Cell culture experiments have shown robust antiviral action towards a whole range of viruses, including HIV-1, dengue, Zika and West Nile Virus, Venezuelan equine encephalitis virus, Chikungunya, pseudorabies virus, adenovirus, and SARS-CoV-2 (COVID-19). Close to 70 clinical trials are currently in progress worldwide for SARS-CoV-2. Although few of these studies have been completed, the results that are available, as well as those from observational/retrospective studies, indicate clinical benefit. Here we discuss the case for ivermectin as a host-directed broad-spectrum antiviral agent, including for SARS-CoV-2.
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Affiliation(s)
- David A Jans
- Nuclear Signaling Lab., Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Australia.
| | - Kylie M Wagstaff
- Cancer Targeting and Nuclear Therapeutics Lab., Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Australia.
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15
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Shechter S, Thomas DR, Jans DA. Application of In Silico and HTS Approaches to Identify Nuclear Import Inhibitors for Venezuelan Equine Encephalitis Virus Capsid Protein: A Case Study. Front Chem 2020; 8:573121. [PMID: 33505952 PMCID: PMC7832173 DOI: 10.3389/fchem.2020.573121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 10/12/2020] [Indexed: 01/16/2023] Open
Abstract
The development of new drugs is costly and time-consuming, with estimates of over $US1 billion and 15 years for a product to reach the market. As understanding of the molecular basis of disease improves, various approaches have been used to target specific molecular interactions in the search for effective drugs. These include high-throughput screening (HTS) for novel drug identification and computer-aided drug design (CADD) to assess the properties of putative drugs before experimental work begins. We have applied conventional HTS and CADD approaches to the problem of identifying antiviral compounds to limit infection by Venezuelan equine encephalitis virus (VEEV). Nuclear targeting of the VEEV capsid (CP) protein through interaction with the host nuclear import machinery has been shown to be essential for viral pathogenicity, with viruses incapable of this interaction being greatly attenuated. Our previous conventional HTS and in silico structure-based drug design (SBDD) screens were successful in identifying novel inhibitors of CP interaction with the host nuclear import machinery, thus providing a unique opportunity to assess the relative value of the two screening approaches directly. This focused review compares and contrasts the two screening approaches, together with the properties of the inhibitors identified, as a case study for parallel use of the two approaches to identify antivirals. The utility of SBDD screens, especially when used in parallel with traditional HTS, in identifying agents of interest to target the host-pathogen interface is highlighted.
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Affiliation(s)
- Sharon Shechter
- Shechter Computational Solutions, Andover, MA, United States.,Department of Chemistry, College of Sciences, University of Massachusetts Lowell, Lowell, MA, United States
| | - David R Thomas
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Biomedical Discovery Institute, Monash University, Monash, VIC, Australia
| | - David A Jans
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Biomedical Discovery Institute, Monash University, Monash, VIC, Australia
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16
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Ivermectin as a Broad-Spectrum Host-Directed Antiviral: The Real Deal? Cells 2020; 9:cells9092100. [PMID: 32942671 PMCID: PMC7564151 DOI: 10.3390/cells9092100] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 09/04/2020] [Accepted: 09/09/2020] [Indexed: 12/12/2022] Open
Abstract
The small molecule macrocyclic lactone ivermectin, approved by the US Food and Drug Administration for parasitic infections, has received renewed attention in the last eight years due to its apparent exciting potential as an antiviral. It was identified in a high-throughput chemical screen as inhibiting recognition of the nuclear localizing Human Immunodeficiency Virus-1 (HIV-1) integrase protein by the host heterodimeric importin (IMP) α/β1 complex, and has since been shown to bind directly to IMPα to induce conformational changes that prevent its normal function in mediating nuclear import of key viral and host proteins. Excitingly, cell culture experiments show robust antiviral action towards HIV-1, dengue virus (DENV), Zika virus, West Nile virus, Venezuelan equine encephalitis virus, Chikungunya virus, Pseudorabies virus, adenovirus, and SARS-CoV-2 (COVID-19). Phase III human clinical trials have been completed for DENV, with >50 trials currently in progress worldwide for SARS-CoV-2. This mini-review discusses the case for ivermectin as a host-directed broad-spectrum antiviral agent for a range of viruses, including SARS-CoV-2.
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17
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Inhibition of Human Adenovirus Replication by the Importin α/β1 Nuclear Import Inhibitor Ivermectin. J Virol 2020; 94:JVI.00710-20. [PMID: 32641484 DOI: 10.1128/jvi.00710-20] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/02/2020] [Indexed: 02/07/2023] Open
Abstract
Human adenoviruses (HAdV) are ubiquitous within the human population and comprise a significant burden of respiratory illnesses worldwide. Pediatric and immunocompromised individuals are at particular risk for developing severe disease; however, no approved antiviral therapies specific to HAdV exist. Ivermectin is an FDA-approved broad-spectrum antiparasitic drug that also exhibits antiviral properties against a diverse range of viruses. Its proposed function is inhibiting the classical protein nuclear import pathway mediated by importin-α (Imp-α) and -β1 (Imp-β1). Many viruses, including HAdV, rely on this host pathway for transport of viral proteins across the nuclear envelope. In this study, we show that ivermectin inhibits HAdV-C5 early gene transcription, early and late protein expression, genome replication, and production of infectious viral progeny. Similarly, ivermectin inhibits genome replication of HAdV-B3, a clinically important pathogen responsible for numerous recent outbreaks. Mechanistically, we show that ivermectin disrupts binding of the viral E1A protein to Imp-α without affecting the interaction between Imp-α and Imp-β1. Our results further extend ivermectin's broad antiviral activity and provide a mechanistic underpinning for its mode of action as an inhibitor of cellular Imp-α/β1-mediated nuclear import.IMPORTANCE Human adenoviruses (HAdVs) represent a ubiquitous and clinically important pathogen without an effective antiviral treatment. HAdV infections typically cause mild symptoms; however, individuals such as children, those with underlying conditions, and those with compromised immune systems can develop severe disseminated disease. Our results demonstrate that ivermectin, an FDA-approved antiparasitic agent, is effective at inhibiting replication of several HAdV types in vitro This is in agreement with the growing body of literature suggesting ivermectin has broad antiviral activity. This study expands our mechanistic knowledge of ivermectin by showing that ivermectin targets the ability of importin-α (Imp-α) to recognize nuclear localization sequences, without effecting the Imp-α/β1 interaction. These data also exemplify the applicability of targeting host factors upon which viruses rely as a viable antiviral strategy.
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18
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Hu M, Bogoyevitch MA, Jans DA. Impact of Respiratory Syncytial Virus Infection on Host Functions: Implications for Antiviral Strategies. Physiol Rev 2020; 100:1527-1594. [PMID: 32216549 DOI: 10.1152/physrev.00030.2019] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Respiratory syncytial virus (RSV) is one of the leading causes of viral respiratory tract infection in infants, the elderly, and the immunocompromised worldwide, causing more deaths each year than influenza. Years of research into RSV since its discovery over 60 yr ago have elucidated detailed mechanisms of the host-pathogen interface. RSV infection elicits widespread transcriptomic and proteomic changes, which both mediate the host innate and adaptive immune responses to infection, and reflect RSV's ability to circumvent the host stress responses, including stress granule formation, endoplasmic reticulum stress, oxidative stress, and programmed cell death. The combination of these events can severely impact on human lungs, resulting in airway remodeling and pathophysiology. The RSV membrane envelope glycoproteins (fusion F and attachment G), matrix (M) and nonstructural (NS) 1 and 2 proteins play key roles in modulating host cell functions to promote the infectious cycle. This review presents a comprehensive overview of how RSV impacts the host response to infection and how detailed knowledge of the mechanisms thereof can inform the development of new approaches to develop RSV vaccines and therapeutics.
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Affiliation(s)
- MengJie Hu
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria, Australia; and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - Marie A Bogoyevitch
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria, Australia; and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
| | - David A Jans
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Victoria, Australia; and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia
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19
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Yang SNY, Atkinson SC, Wang C, Lee A, Bogoyevitch MA, Borg NA, Jans DA. The broad spectrum antiviral ivermectin targets the host nuclear transport importin α/β1 heterodimer. Antiviral Res 2020; 177:104760. [PMID: 32135219 DOI: 10.1016/j.antiviral.2020.104760] [Citation(s) in RCA: 193] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/28/2020] [Accepted: 02/28/2020] [Indexed: 12/11/2022]
Abstract
Infection by RNA viruses such as human immunodeficiency virus (HIV)-1, influenza, and dengue virus (DENV) represent a major burden for human health worldwide. Although RNA viruses replicate in the infected host cell cytoplasm, the nucleus is central to key stages of the infectious cycle of HIV-1 and influenza, and an important target of DENV nonstructural protein 5 (NS5) in limiting the host antiviral response. We previously identified the small molecule ivermectin as an inhibitor of HIV-1 integrase nuclear entry, subsequently showing ivermectin could inhibit DENV NS5 nuclear import, as well as limit infection by viruses such as HIV-1 and DENV. We show here that ivermectin's broad spectrum antiviral activity relates to its ability to target the host importin (IMP) α/β1 nuclear transport proteins responsible for nuclear entry of cargoes such as integrase and NS5. We establish for the first time that ivermectin can dissociate the preformed IMPα/β1 heterodimer, as well as prevent its formation, through binding to the IMPα armadillo (ARM) repeat domain to impact IMPα thermal stability and α-helicity. We show that ivermectin inhibits NS5-IMPα interaction in a cell context using quantitative bimolecular fluorescence complementation. Finally, we show for the first time that ivermectin can limit infection by the DENV-related West Nile virus at low (μM) concentrations. Since it is FDA approved for parasitic indications, ivermectin merits closer consideration as a broad spectrum antiviral of interest.
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Affiliation(s)
- Sundy N Y Yang
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Sarah C Atkinson
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Chunxiao Wang
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Alexander Lee
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - Marie A Bogoyevitch
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, Australia
| | - Natalie A Borg
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia
| | - David A Jans
- Nuclear Signalling Laboratory, Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Vic, 3800, Australia.
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20
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Tessier TM, Dodge MJ, Prusinkiewicz MA, Mymryk JS. Viral Appropriation: Laying Claim to Host Nuclear Transport Machinery. Cells 2019; 8:E559. [PMID: 31181773 PMCID: PMC6627039 DOI: 10.3390/cells8060559] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/05/2019] [Accepted: 06/06/2019] [Indexed: 12/13/2022] Open
Abstract
Protein nuclear transport is an integral process to many cellular pathways and often plays a critical role during viral infection. To overcome the barrier presented by the nuclear membrane and gain access to the nucleus, virally encoded proteins have evolved ways to appropriate components of the nuclear transport machinery. By binding karyopherins, or the nuclear pore complex, viral proteins influence their own transport as well as the transport of key cellular regulatory proteins. This review covers how viral proteins can interact with different components of the nuclear import machinery and how this influences viral replicative cycles. We also highlight the effects that viral perturbation of nuclear transport has on the infected host and how we can exploit viruses as tools to study novel mechanisms of protein nuclear import. Finally, we discuss the possibility that drugs targeting these transport pathways could be repurposed for treating viral infections.
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Affiliation(s)
- Tanner M Tessier
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada.
| | - Mackenzie J Dodge
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada.
| | - Martin A Prusinkiewicz
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada.
| | - Joe S Mymryk
- Department of Microbiology and Immunology, The University of Western Ontario, London, ON N6A 3K7, Canada.
- Department of Otolaryngology, Head & Neck Surgery, The University of Western Ontario, London, ON N6A 3K7, Canada.
- Department of Oncology, The University of Western Ontario, London, ON N6A 3K7, Canada.
- London Regional Cancer Program, Lawson Health Research Institute, London, ON N6A 5W9, Canada.
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21
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DeBono A, Thomas DR, Lundberg L, Pinkham C, Cao Y, Graham JD, Clarke CL, Wagstaff KM, Shechter S, Kehn-Hall K, Jans DA. Novel RU486 (mifepristone) analogues with increased activity against Venezuelan Equine Encephalitis Virus but reduced progesterone receptor antagonistic activity. Sci Rep 2019; 9:2634. [PMID: 30796232 PMCID: PMC6385310 DOI: 10.1038/s41598-019-38671-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 12/27/2018] [Indexed: 12/21/2022] Open
Abstract
There are currently no therapeutics to treat infection with the alphavirus Venezuelan equine encephalitis virus (VEEV), which causes flu-like symptoms leading to neurological symptoms in up to 14% of cases. Large outbreaks of VEEV can result in 10,000 s of human cases and mass equine death. We previously showed that mifepristone (RU486) has anti-VEEV activity (EC50 = 20 μM) and only limited cytotoxicity (CC50 > 100 μM), but a limitation in its use is its abortifacient activity resulting from its ability to antagonize the progesterone receptor (PR). Here we generate a suite of new mifepristone analogues with enhanced antiviral properties, succeeding in achieving >11-fold improvement in anti-VEEV activity with no detectable increase in toxicity. Importantly, we were able to derive a lead compound with an EC50 of 7.2 µM and no detectable PR antagonism activity. Finally, based on our SAR analysis we propose avenues for the further development of these analogues as safe and effective anti-VEEV agents.
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Affiliation(s)
- Aaron DeBono
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, 3052, Australia
| | - David R Thomas
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology School of Biomedical Sciences, Monash University, Melbourne, Australia
| | - Lindsay Lundberg
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA, USA
| | - Chelsea Pinkham
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA, USA
| | - Ying Cao
- Centre for Cancer Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia
| | - J Dinny Graham
- Centre for Cancer Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia
| | - Christine L Clarke
- Centre for Cancer Research, The Westmead Institute for Medical Research, Westmead, NSW, Australia
| | - Kylie M Wagstaff
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology School of Biomedical Sciences, Monash University, Melbourne, Australia
| | | | - Kylene Kehn-Hall
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA, USA
| | - David A Jans
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology School of Biomedical Sciences, Monash University, Melbourne, Australia.
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22
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New World alphavirus protein interactomes from a therapeutic perspective. Antiviral Res 2019; 163:125-139. [PMID: 30695702 DOI: 10.1016/j.antiviral.2019.01.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/18/2019] [Accepted: 01/23/2019] [Indexed: 12/30/2022]
Abstract
The New World alphaviruses, Venezuelan, eastern and western equine encephalitis viruses (VEEV, EEEV, and WEEV), are important human pathogens due to their ability to cause varying levels of morbidity and mortality in humans. There is also concern about VEEV and EEEV being used as bioweapons. Currently, a FDA-approved antiviral is lacking for New World alphaviruses. In this review, the function of each viral protein is discussed with an emphasis on how these functions can be targeted by therapeutics. Both direct acting antivirals as well as inhibitors that impact host protein interactions with viral proteins are described. Non-structural protein 3 (nsP3), capsid, and E2 proteins have garnered attention in recent years, whereas little is known regarding host protein interactions of the other viral proteins and is an important avenue for future study.
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23
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Lundberg L, Fontenot J, Lin SC, Pinkham C, Carey BD, Campbell CE, Kehn-Hall K. Venezuelan Equine Encephalitis Virus Capsid Implicated in Infection-Induced Cell Cycle Delay in vitro. Front Microbiol 2018; 9:3126. [PMID: 30631316 PMCID: PMC6315117 DOI: 10.3389/fmicb.2018.03126] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 12/03/2018] [Indexed: 02/06/2023] Open
Abstract
Venezuelan equine encephalitis virus (VEEV) is a positive sense, single-stranded RNA virus and member of the New World alphaviruses. It causes a biphasic febrile illness that can be accompanied by central nervous system involvement and moderate morbidity in humans and severe mortality in equines. The virus has a history of weaponization, lacks FDA-approved therapeutics and vaccines in humans, and is considered a select agent. Like other RNA viruses, VEEV replicates in the cytoplasm of infected cells and eventually induces apoptosis. The capsid protein, which contains a nuclear localization and a nuclear export sequence, induces a shutdown of host transcription and nucleocytoplasmic trafficking. Here we show that infection with VEEV causes a dysregulation of cell cycling and a delay in the G0/G1 phase in Vero cells and U87MG astrocytes. Cells infected with VEEV encoding a capsid NLS mutant or treated with the capsid-importin α interaction inhibitor G281-1485 were partially rescued from this cell cycle dysregulation. Pathway analysis of previously published RNA-sequencing data from VEEV infected U87MG astrocytes identified alterations of canonical pathways involving cell cycle, checkpoint regulation, and proliferation. Multiple cyclins including cyclin D1, cyclin A2 and cyclin E2 and other regulators of the cell cycle were downregulated in infected cells in a capsid NLS dependent manner. Loss of Rb phosphorylation, which is a substrate for cyclin/cdk complexes was also observed. These data demonstrate the importance of capsid nuclear localization and/or importin α binding for inducing cell cycle arrest and transcriptional downregulation of key cell cycle regulators.
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Affiliation(s)
- Lindsay Lundberg
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA, United States
| | - Jacque Fontenot
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA, United States
| | - Shih-Chao Lin
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA, United States
| | - Chelsea Pinkham
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA, United States
| | - Brian D Carey
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA, United States
| | | | - Kylene Kehn-Hall
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA, United States
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Fahrenkrog B, Harel A. Perturbations in Traffic: Aberrant Nucleocytoplasmic Transport at the Heart of Neurodegeneration. Cells 2018; 7:cells7120232. [PMID: 30486313 PMCID: PMC6316434 DOI: 10.3390/cells7120232] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 11/22/2018] [Accepted: 11/23/2018] [Indexed: 12/25/2022] Open
Abstract
Neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Huntington’s disease (HD), are characterized by intracellular aggregation of proteins. In the case of ALS and FTD, these protein aggregates are found in the cytoplasm of affected neurons and contain certain RNA-binding proteins (RBPs), namely the TAR DNA-binding protein of 43 kDa (TDP-43) and the fused in sarcoma (FUS) gene product. TDP-43 and FUS are nuclear proteins and their displacement to the cytoplasm is thought to be adverse in at least two ways: loss-of-function in the nucleus and gain-of-toxicity in the cytoplasm. In the case of HD, expansion of a polyglutamine (polyQ) stretch within the N-terminal domain of the Huntingtin (HTT) protein leads to nuclear accumulation of polyQ HTT (or mHTT) and a toxic gain-of-function phenotype resulting in neurodegeneration. Numerous studies in recent years have provided evidence that defects in nucleocytoplasmic transport critically contribute to the pathology of these neurodegenerative diseases. A new mechanistic view is emerging, implicating three types of perturbations in normal cellular pathways that rely on nucleocytoplasmic transport: displacement of nuclear transport receptors and nucleoporins from nuclear pore complexes (NPCs), mislocalization and aggregation of RNA-binding proteins, and weakening of the chaperone activity of nuclear import receptors.
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Affiliation(s)
- Birthe Fahrenkrog
- Institute of Molecular Biology and Medicine, Université Libre de Bruxelles, 6041 Charleroi, Belgium.
| | - Amnon Harel
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed 1311502, Israel.
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