Strategies to inhibit viral protein nuclear import: HIV-1 as a target

Levin, Aviad; Loyter, Abraham; Bukrinsky, Michael

doi:10.1016/j.bbamcr.2010.07.010

Cited by 19 publications

(13 citation statements)

References 111 publications

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“…The vDNA together with the nucleocapsid (NC), reverse transcriptase (RT), Vpr, and integrase (IN) form the pre-integration complex (PIC). The PIC is transported to the nucleus by way of microtubules and actin filaments in the cytoplasm [1,2], and subsequently enters the nucleus by mechanisms which have only recently begun to be examined in detail [3]. Inside the nucleus, the HIV-1 DNA is integrated into host cell chromatin, after which the provirus is transcribed for viral protein expression for particle assembly and release from the cell.…”

Section: Introductionmentioning

confidence: 99%

Evidence for biphasic uncoating during HIV-1 infection from a novel imaging assay

et al. 2013

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BackgroundUncoating of the HIV-1 core plays a critical role during early post-fusion stages of infection but is poorly understood. Microscopy-based assays are unable to easily distinguish between intact and partially uncoated viral cores.ResultsIn this study, we used 5-ethynyl uridine (EU) to label viral-associated RNA during HIV production. At early time points after infection with EU-labeled virions, the viral-associated RNA was stained with an EU-specific dye and was detected by confocal microscopy together with viral proteins. We observed that detection of the viral-associated RNA was specific for EU-labeled virions, was detected only after viral fusion with target cells, and occurred after an initial opening of the core. In vitro staining of cores showed that the opening of the core allowed the small molecule dye, but not RNase A or antibodies, inside. Also, staining of the viral-associated RNA, which is co-localized with nucleocapsid, decays over time after viral infection. The decay rate of RNA staining is dependent on capsid (CA) stability, which was altered by CA mutations or a small molecule inducer of HIV-1 uncoating. While the staining of EU-labeled RNA was not affected by inhibition of reverse transcription, the kinetics of core opening of different CA mutants correlated with initiation of reverse transcription. Analysis of the E45A CA mutant suggests that initial core opening is independent of complete capsid disassembly.ConclusionsTaken together, our results establish a novel RNA accessibility-based assay that detects an early event in HIV-1 uncoating and can be used to further define this process.

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Section: Introductionmentioning

confidence: 99%

Evidence for biphasic uncoating during HIV-1 infection from a novel imaging assay

et al. 2013

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“…However, LEDGF might be involved in nuclear import in either an NLS-dependent or -independent manner. More intense studies are needed to confirm its genuine role in the lentiviral life cycle (Llano et al 2004a;Levin et al 2010aLevin et al , 2011.…”

Section: Ledgfmentioning

confidence: 99%

“…Current research indicates an orches-trated protein-protein network is required for retroviral nuclear transport. Since different cell lines have distinctive cell signaling pathways and cellular status, these parameters may influence the nuclear import of retroviral PICs (Levin et al 2011).…”

Section: Conclusion and Future Perspectivesmentioning

confidence: 99%

Cellular and viral determinants of retroviral nuclear entry

2016

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Retroviruses must integrate their cDNA into the host genome to generate proviruses. Viral DNA-protein complexes interact with cellular proteins and produce pre-integration complexes, which carry the viral genome and cross the nuclear pore channel to enter the nucleus and integrate viral DNA into host chromosomal DNA. If the reverse transcripts fail to integrate, linear or circular DNA species such as 1-and 2-long terminal repeats are generated. Such complexes encounter numerous cellular proteins in the cytoplasm, which restrict viral infection and protect the nucleus. To overcome host cell defenses, the pathogens have evolved several evasion strategies. Viral proteins often contain nuclear localization signals, allowing entry into the nucleus. Among more than 1000 proteins identified as required for HIV infection by RNA interference screening, karyopherins, cleavage and polyadenylation specific factor 6, and nucleoporins have been predominantly studied. This review discusses current opinions about the synergistic relationship between the viral and cellular factors involved in nuclear import, with focus on the unveiled mysteries of the host-pathogen interaction, and highlights novel approaches to pinpoint therapeutic targets.

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“…T he nuclear pore is the conduit for transport between the cytoplasm and the nucleus, and as such, it represents an obligatory pathway that must be navigated very early after infection by many classes of human viruses (9,20,21,27,36,44,50,60,62). For herpesviruses, capsid-tegument assemblies must be transported across the cytoplasm, be targeted to and interact with pores, and undergo structural rearrangements promoting genome exit and transport across the pore to the nucleus, where virus immediate early gene transcription ensues (14).…”

mentioning

confidence: 99%

A Nuclear Localization Signal in Herpesvirus Protein VP1-2 Is Essential for Infection via Capsid Routing to the Nuclear Pore

Abaitua

Hollinshead

Bolstad

et al. 2012

J Virol

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To initiate infection, herpesviruses must navigate to and transport their genomes across the nuclear pore. VP1-2 is a large structural protein of the virion that is conserved in all herpesviruses and plays multiple essential roles in virus replication, including roles in early entry. VP1-2 contains an N-terminal basic motif which functions as an efficient nuclear localization signal (NLS). In this study, we constructed a mutant HSV strain, K.VP1-2ΔNLS, which contains a 7-residue deletion of the core NLS at position 475. This mutant fails to spread in normal cells but can be propagated in complementing cell lines. Electron microscopy (EM) analysis of infection in noncomplementing cells demonstrated capsid assembly, cytoplasmic envelopment, and the formation of extracellular enveloped virions. Furthermore, extracellular virions isolated from noncomplementing cells had similar profiles and abundances of structural proteins. Virions containing VP1-2ΔNLS were able to enter and be transported within cells. However, further progress of infection was prevented, with at least a 500- to 1,000-fold reduction in the efficiency of initiating gene expression compared to that in the revertant. Ultrastructural and immunofluorescence analyses revealed that the K.VP1-2ΔNLS mutant was blocked at the microtubule organizing center or immediately upstream of nuclear pore docking and prior to gene expression. These results indicate that the VP1-2 NLS is not required for the known assembly functions of the protein but is a key requirement for the early routing to the nuclear pore that is necessary for successful infection. Given its conservation, we propose that this motif may also be critical for entry of other classes of herpesviruses.

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Strategies to inhibit viral protein nuclear import: HIV-1 as a target

Cited by 19 publications

References 111 publications

Evidence for biphasic uncoating during HIV-1 infection from a novel imaging assay

Evidence for biphasic uncoating during HIV-1 infection from a novel imaging assay

Cellular and viral determinants of retroviral nuclear entry

A Nuclear Localization Signal in Herpesvirus Protein VP1-2 Is Essential for Infection via Capsid Routing to the Nuclear Pore

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