Ivermectin is a specific inhibitor of importin alpha/beta-mediated nuclear import able to inhibit replication of HIV-1 and Dengue virus

Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
Biochemical Journal (Impact Factor: 4.4). 03/2012; 443(3):851-6. DOI: 10.1042/BJ20120150
Source: PubMed


The movement of proteins between the cytoplasm and nucleus mediated by the importin superfamily of proteins is essential to many cellular processes, including differentiation and development, and is critical to disease states such as viral disease and oncogenesis. We recently developed a high-throughput screen to identify specific and general inhibitors of protein nuclear import, from which ivermectin was identified as a potential inhibitor of importin α/β-mediated transport. In the present study, we characterized in detail the nuclear transport inhibitory properties of ivermectin, demonstrating that it is a broad-spectrum inhibitor of importin α/β nuclear import, with no effect on a range of other nuclear import pathways, including that mediated by importin β1 alone. Importantly, we establish for the first time that ivermectin has potent antiviral activity towards both HIV-1 and dengue virus, both of which are strongly reliant on importin α/β nuclear import, with respect to the HIV-1 integrase and NS5 (non-structural protein 5) polymerase proteins respectively. Ivermectin would appear to be an invaluable tool for the study of protein nuclear import, as well as the basis for future development of antiviral agents.

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Available from: Kylie Michelle Wagstaff, May 08, 2015
    • "The Wagstaff group showed that Ivermectin inhibits importin α/β-dependent import with no effects on a range of other nuclear transport pathways involving members of the importin protein family. This is in line with recent literature, demonstrating e.g. that Ivermectin possesses potent antiviral activity by inhibiting replication of human immunodeficiency virus (HIV) and dengue virus due to its effect on importins (Wagstaff et al., 2012; Tay et al., 2013; Fraser et al., 2014). Furthermore, it is able to alter capsid protein distribution in mammalian cells resulting in a reduced replication of Venezuelan Equine Encephalitis virus (Lundberg et al., 2013). "
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    ABSTRACT: Hypoxia-inducible transcription factors (HIFs) regulate hundreds of genes involved in cellular adaptation to reduced oxygen availability. HIFs consist of an O2-labile α-subunit (primarily HIF-1α and HIF-2α) and a constitutive HIF-1β subunit. In normoxia the HIF-α subunit is hydroxylated by members of a family of prolyl-4-hydroxylase domain (PHD) proteins, PHD1-3, resulting in recognition by von Hippel-Lindau protein, ubiquitination and proteasomal degradation. In contrast, reduced oxygen availability inhibits PHD activity resulting in HIF-1α stabilisation and nuclear accumulation. Nuclear import of HIF-1α mainly depends on classical nuclear localisation signals (NLS) and involves importin α/β heterodimers. Recently, a specific inhibitor of nuclear import has been identified that inhibits importin α/β-dependent import with no effects on a range of other nuclear transport pathways involving members of the importin protein family. In this study we evaluated the physiological activity of this importin α/β-inhibitor (Ivermectin) in the hypoxia response pathway. Treatment with Ivermectin decreases binding activity of HIF-1α to the importin α/β-heterodimer. Moreover, HIF-1α nuclear localisation, nuclear HIF-1α protein levels, HIF-target gene expression, as well as HIF-transcriptional activity are reduced upon Ivermectin treatment. For the first time, we demonstrate the effect of specific importin α/β-inhibition on the hypoxic response on the molecular level.
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    • "Moreover, we have not observed significant changes in EHV-1 replication in murine neurons in the presence of a wide range of leptomycin B concentrations (Fig. 1 C-D), thus it can be assumed that EHV-1 was not dependent on the exportin 1-mediated nuclear export . Many studies have previously confirmed that ivermectin is able to inhibit replication of HIV-1, dengue virus and West Nile virus (Mastrangelo et al. 2012, Wagstaff et al. 2012). It has been demonstrated that ivermectin is affecting NS3 helicase activity, required during viral RNA replication. "

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    • "Indeed, knockdown of importin β1 and treatment with ivermectin both inhibited infection, supporting a model where BKPyV co-opts this endogenous nuclear entry mechanism using the NLS of the minor capsid proteins. The nuclear import inhibitor ivermectin specifically targets the importin α/β1-mediated import pathway without affecting the other import pathways including importin β–mediated and transportin-mediated import (Wagstaff et al., 2012). The NLS is recognized first by the adapter importin α, then importin β1 interacts with the substrate-NLS-importin α complex to allow transport through the nuclear pore (Yoneda et al., 1999). "
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    ABSTRACT: BK Polyomavirus (BKPyV) is a ubiquitous nonenveloped human virus that can cause severe disease in immunocompromised populations. After internalization into renal proximal tubule epithelial cells, BKPyV traffics through the ER and enters the cytosol. However, it is unclear how the virus enters the nucleus. In this study, we elucidate a role for the nuclear localization signal located on the minor capsid proteins VP2 and VP3 during infection. Site-directed mutagenesis of a single lysine in the basic region of the C-terminus of the minor capsid proteins abrogated their nuclear localization, and the analogous genomic mutation reduced infectivity. Additionally, through use of the inhibitor ivermectin and knockdown of importin β1, we found that the importin α/β pathway is involved during infection. Overall these data are the first to show the significance of the NLS of the BKPyV minor capsid proteins during infection in a natural host cell. Copyright © 2014 Elsevier Inc. All rights reserved.
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