Inhibitory function of adapter-related protein complex 2 alpha 1 subunit in the process of nuclear translocation of human immunodeficiency virus type 1 genome

Microbicide Containing Ellagic Acid Can Inhibit HIV-1 Infection

OBJECTIVES

Ellagic acid (EA) has a wide range of biological effects. The purpose of this study was to investigate the in vitro effects of EA on HIV-1 replication, viral enzyme activity and cytokine secretion by infected cells.

METHODS

The anti-HIV-1 activity of EA in solution was determined in vitro using the infection of TZM-bl cells by the nano luciferase-secreting R5-tropic JRCSF strain of HIV-1, which allows for the quantification of viral growth by measuring nano luciferase in the culture supernatants. The effect of EA on the cytokine secretion of TZM-bl cells was determined by a multiplexed bead array after 48 h of HIV-1 exposure. The antiviral effect of EA in the gel formulation (Ellagel), as would be used for vaginal application, was investigated by the inhibition of infection of UC87.CD4.CCR5 cells with R5-tropic pBaLEnv-recombinant HIV-1.

RESULTS

EA in solutions of up to 100 µM was not toxic to TZM-bl cells. EA added either 1 h before or 4 h after HIV-1 exposure suppressed the replication of R5-tropic HIV-1 in TZM-bl cells in a dose-dependent manner, with up to 69% inhibition at 50 µM. EA-containing solutions also exhibited a dose-dependent inhibitory effect on HIV-1 replication in U87 cells. When EA was formulated as a gel, Ellagel containing 25 µM and 50 µM EA inhibited HIV-1 replication in U87 cells by 56% and 84%, respectively. In assays of specific HIV-1 enzyme activity, Ellagel inhibited HIV-1 integrase but not protease. EA did not significantly modulate cytokine secretion.

CONCLUSIONS

We conclude that EA either in solution or in a gel form inhibits HIV infection without adverse effects on target cells. Thus, gel containing EA can be tested as a new microbicide against HIV infection.

GTPase Activity of MxB Contributes to Its Nuclear Location, Interaction with Nucleoporins and Anti-HIV-1 Activity

The human myxovirus resistance 2 (Mx2/MxB) protein, a member of interferon (IFN)-inducible dynamin-like large GTPases, restricts a number of virus infections. Inhibition of these viruses occurs at poorly-defined steps after viral entry and has a common requirement for MxB oligomerization. However, the GTPase activity is essential for the anti-viral effects of MxB against herpesviruses and HBV but not HIV-1. To understand the role of MxB GTPase activity, including GTP binding and GTP hydrolysis, in restriction of HIV-1 infection, we genetically separated these two functions and evaluated their contributions to restriction. We found that both the GTP binding and hydrolysis function of MxB involved in the restriction of HIV-1 replication. The GTPase activity of MxB contributed to its nuclear location, interaction with nucleoporins (NUPs) and HIV-1 capsids. Furthermore, MxB disrupted the association between NUPs and HIV-1 cores dependently upon its GTPase activity. The function of GTPase activity was therefore multi-faceted, led to fundamentally distinct mechanisms employed by wild-type MxB and GTPase activity defective MxB mutations to restrict HIV-1 replication.

MxB impedes the NUP358-mediated HIV-1 pre-integration complex nuclear import and viral replication cooperatively with CPSF6

BACKGROUND

The human myxovirus resistance 2 (Mx2/MxB) protein was originally found to regulate cytoplasmic-nuclear transport but was recently reported to restrict HIV-1 replication by binding to HIV-1 capsid (CA), preventing uncoating, the nuclear import of pre-integration complex (PIC) and viral DNA integration. This work explores the mechanisms of MxB-mediated HIV-1 inhibition.

RESULTS

We demonstrated that MxB represses NUP358-mediated PIC nuclear import and HIV-1 replication. Moreover, MxB's effects on PIC nuclear import and HIV-1 replication depend critically on cofactor cleavage and polyadenylation specificity factor subunit 6 (CPSF6). MxB binds nucleoporin NUP358, blocks NUP358-CA interaction, thereby impeding the nuclear import of HIV-1 PIC with CPSF6 binding to PIC. More intriguingly, CPSF6's role in nuclear import depends on MxB, being a facilitator of HIV-1 nuclear import on its own, but becoming an inhibitor when MxB is present.

CONCLUSIONS

Our work establishes that MxB impedes the NUP358-mediated HIV-1 nuclear import and viral replication cooperatively with CPSF6.

Neuroinflammation, oxidative stress, and blood-brain barrier (BBB) disruption in acute Utah electrode array implants and the effect of deferoxamine as an iron chelator on acute foreign body response

The use of intracortical microelectrode arrays has gained significant attention in being able to help restore function in paralysis patients and study the brain in various neurological disorders. Electrode implantation in the cortex causes vasculature or blood-brain barrier (BBB) disruption and thus elicits a foreign body response (FBR) that results in chronic inflammation and may lead to poor electrode performance. In this study, a comprehensive insight into the acute molecular mechanisms occurring at the Utah electrode array-tissue interface is provided to understand the oxidative stress, neuroinflammation, and neurovascular unit (astrocytes, pericytes, and endothelial cells) disruption that occurs following microelectrode implantation. Quantitative real time polymerase chain reaction (qRT-PCR) was used to quantify the gene expression at acute time-points of 48-hr, 72-hr, and 7-days for factors mediating oxidative stress, inflammation, and BBB disruption in rats implanted with a non-functional 4 × 4 Utah array in the somatosensory cortex. During vascular disruption, free iron released into the brain parenchyma can exacerbate the FBR, leading to oxidative stress and thus further contributing to BBB degradation. To reduce the free iron released into the brain tissue, the effects of an iron chelator, deferoxamine mesylate (DFX), was also evaluated.

Landscape of nuclear transport receptor cargo specificity

Nuclear transport receptors (NTRs) recognize localization signals of cargos to facilitate their passage across the central channel of nuclear pore complexes (NPCs). About 30 different NTRs constitute different transport pathways in humans and bind to a multitude of different cargos. The exact cargo spectrum of the majority of NTRs, their specificity and even the extent to which active nucleocytoplasmic transport contributes to protein localization remains understudied because of the transient nature of these interactions and the wide dynamic range of cargo concentrations. To systematically map cargo-NTR relationships in situ, we used proximity ligation coupled to mass spectrometry (BioID). We systematically fused the engineered biotin ligase BirA* to 16 NTRs. We estimate that a considerable fraction of the human proteome is subject to active nuclear transport. We quantified the specificity and redundancy in NTR interactions and identified transport pathways for cargos. We extended the BioID method by the direct identification of biotinylation sites. This approach enabled us to identify interaction interfaces and to discriminate direct versus piggyback transport mechanisms. Data are available via ProteomeXchange with identifier PXD007976.

Evaluation of novel protease inhibitors against darunavir-resistant variants of HIV type 1

HIV disease became a manageable chronic disease since combination antiretroviral therapy (cART) was introduced as the standard treatment regimen. However, the emergence of drug‐resistant viruses is a major problem associated with cART. A phenotypic drug susceptibility test using a lentiviral vector was established and applied to evaluate new protease inhibitors (PIs). Lentiviral vectors representing a wild‐type (WT‐lentivector) and darunavir (DRV)‐resistant HIV type 1 (HIV‐1) (DRV^r‐lentivector) were generated. Nine clinically approved protease inhibitors (PIs) inhibited the transduction ability of WT‐lentivector similar to their inhibitory effects on the replication of WT HIV‐1. Three new PIs reduced the transduction ability of WT‐ and DRV^r‐lentivector, suggesting that these PIs may be the candidates as novel antiretroviral drugs against drug‐resistant variants of HIV‐1.

Neutralization breadth and potency of serum derived from recently human immunodeficiency virus type 1-infected Thai individuals

Neutralizing antibody responses play important roles in controlling several viral infections including human immunodeficiency virus type 1 (HIV-1). Potent and broad neutralizing antibody responses have been reported in some HIV-1-infected individuals; therefore, elucidating the mechanisms underlying neutralizing antibody responses will provide important information for the development of anti-HIV-1 vaccines. We herein performed a comparative study on the neutralization breadth and potency of serum samples collected from Thai individuals recently and chronically infected with HIV-1. Neutralization tests using a series of envelope glycoproteins (Env)-recombinant viruses revealed that although several serum samples derived from recently infected individuals did not show any HIV-1-specific neutralizing activity, the remaining serum samples exhibited neutralizing activity not only for recombinant viruses with CRF01_AE Env, but also for viruses with subtypes B and C Env. Furthermore, some serum samples derived from recently infected individuals showed the neutralization potency. Our results may provide a deeper insight into the characteristics of neutralizing antibody responses that develop during the course of HIV-1 infection among individuals in Thailand.

MARCH8 inhibits HIV-1 infection by reducing virion incorporation of envelope glycoproteins

Membrane-associated RING-CH 8 (MARCH8) is one of 11 members of the recently discovered MARCH family of RING (really interesting new gene)-finger E3 ubiquitin ligases. MARCH8 downregulates several host transmembrane proteins, including major histocompatibility complex (MHC)-II, CD86, interleukin (IL)-1 receptor accessory protein, TNF-related apoptosis-inducing ligand (TRAIL) receptor 1 and the transferrin receptor. However, its physiological roles remain largely unknown. Here we identify MARCH8 as a novel antiviral factor. The ectopic expression of MARCH8 in virus-producing cells does not affect levels of lentivirus production, but it does markedly reduce viral infectivity. MARCH8 blocks the incorporation of HIV-1 envelope glycoprotein into virus particles by downregulating it from the cell surface, probably through their interaction, resulting in a substantial reduction in the efficiency of viral entry. The inhibitory effect of MARCH8 on vesicular stomatitis virus G-glycoprotein is even more remarkable, suggesting a broad-spectrum inhibition of enveloped viruses by MARCH8. Notably, the endogenous expression of MARCH8 is high in monocyte-derived macrophages and dendritic cells, and MARCH8 knockdown or knockout in macrophages significantly increases the infectivity of virions produced by these cells. Our findings thus indicate that MARCH8 is highly expressed in terminally differentiated myeloid cells, and that it is a potent antiviral protein that targets viral envelope glycoproteins and reduces their incorporation into virions.

Characterization of human immunodeficiency virus type 1 CRF01_AE env genes derived from recently infected Thai individuals

Transmitted/founder virus is responsible for the establishment of human immunodeficiency virus type 1 (HIV-1) infection and induces primary anti-HIV-1 immune responses; therefore, it is important to study the viral population to understand the early events of HIV-1 infection. We amplified HIV-1 env genes from sera derived from recently infected Thai individuals, and established envelope glycoproteins (Env)-recombinant viruses. Generated Env-recombinant viruses were tested for their neutralization susceptibility to neutralizing human monoclonal antibodies (NHMAbs) and entry inhibitors, as well as being subjected to genotypic analysis. Most recombinant viruses were susceptible to neutralization by NHMAbs to Env gp41, whereas approximately one-third of the recombinant viruses were susceptible to a NHMAb against the CD4 binding site of gp120. In addition, all env genes were classified into CRF01_AE genes and showed low genetic divergence. Taken together with our previous studies on CRF01_AE env genes derived from chronically infected Thai individuals, these results suggested that the immunological and genetic characteristics of CRF01_AE Env derived from recently infected Thai individuals were different from those derived from chronically infected individuals.

PIP2: choreographer of actin-adaptor proteins in the HIV-1 dance

The actin cytoskeleton plays a key role during the replication cycle of human immunodeficiency virus-1 (HIV-1). HIV-1 infection is affected by cellular proteins that influence the clustering of viral receptors or the subcortical actin cytoskeleton. Several of these actin-adaptor proteins are controlled by the second messenger phosphatidylinositol 4,5-biphosphate (PIP2), an important regulator of actin organization. PIP2 production is induced by HIV-1 attachment and facilitates viral infection. However, the importance of PIP2 in regulating cytoskeletal proteins and thus HIV-1 infection has been overlooked. This review examines recent reports describing the roles played by actin-adaptor proteins during HIV-1 infection of CD4+ T cells, highlighting the influence of the signaling lipid PIP2 in this process.

Impact of amino acid variations in Gag and protease of HIV type 1 CRF01_AE strains on drug susceptibility of virus to protease inhibitors

BACKGROUND

Protease (PR) inhibitors (PIs) were designed against subtype B virus of human immunodeficiency virus type 1 (HIV-1), but believed to retain its activity against most of the other subtypes. CRF01_AE PR (AE-PR) contains background mutations that are presumed to alter the drug susceptibility of PR. In addition, amino acid variations found in HIV-1 Gag potentially affect the drug susceptibility or catalytic efficiency of PR.

METHODS

We studied the impact of naturally occurring amino acid substitutions found in AE-PR and CRF01_AE Gag (AE-Gag) on the drug susceptibility of PR to 9 currently available PIs, using the pNL4-3-derived luciferase reporter virus containing AE-Gag and/or AE-PR genes derived from drug treatment-naïve, HIV-1-infected Thai patients.

RESULTS

Sequencing analysis revealed that several mutations were detected in deduced amino acid sequences of AE-PR and AE-Gag genes, as compared to these genes of pNL4-3. Drug susceptibility tests revealed that AE-PR showed a variety of susceptibilities to 9 PIs compared with pNL4-3 PR. In addition, AE-Gag significantly reduced the drug susceptibility of AE-PR and pNL4-3 PR.

CONCLUSION

Our results suggest that amino acid variations in AE-PR and AE-Gag play roles in determining the drug susceptibility of CRF01_AE viruses to PIs.

Short communication: RNA interference directed against Axin1 upregulates human immunodeficiency virus type 1 gene expression by activating the Wnt signaling pathway in HeLa-derived J111 cells

Axin1, a regulator of Wnt signaling, was previously identified as playing a negative role in the late phase of human immunodeficiency virus type 1 (HIV-1) replication in HeLa-derived J111 cells. In this report, we studied the molecular mechanism of how Axin1 regulates HIV-1 replication. HIV-1 transactivator, Tat-dependent viral reporter gene expression was enhanced in J111 cells transfected with small interfering RNA (siRNA) against Axin1. In addition, viral transcription was upregulated in J111 cells transfected with siRNA against Axin1. In contrast, HIV-1 gene expression was not enhanced by transfecting HeLa cells with siRNA against Axin1. The expression levels of T cell factor-4 (TCF4) and beta-catenin were higher in J111 than HeLa cells. In addition, siRNAs against TCF4 and beta-catenin inhibited the Axin1 siRNA-dependent enhancement of HIV-1 gene expression in J111 cells. These results suggest that Axin1 plays a negative role in HIV-1 transcription through the Wnt signaling pathway in J111 cells under normal cell culture conditions.

Phenotypic studies on recombinant human immunodeficiency virus type 1 (HIV-1) containing CRF01_AE env gene derived from HIV-1-infected patient, residing in central Thailand

Human immunodeficiency virus type 1 (HIV-1) env genes were cloned from blood samples of HIV-1-infected Thai patients, and 35 infectious CRF01_AE envelope glycoprotein (Env)-recombinant viruses were established. In this report, we examined the neutralization susceptibility of these viruses to human monoclonal antibodies, 2G12, IgG1 b12, 2F5 and 4E10, pooled patient plasma, coreceptor antagonists and fusion inhibitor, T-20. The neutralization susceptibility of CRF01_AE Env-recombinant viruses to 2F5, 4E10, patient plasma, coreceptor antagonists and T-20 varied, while most viruses showed low susceptibility to 2G12 and IgG1 b12. Several dual-tropic viruses showed lower susceptibility to 2F5 and 4E10 than CXCR4- or CCR5-tropic viruses. Neutralization susceptibility of the CRF01_AE Env-recombinant virus to pooled patient plasma was negatively correlated with the length of the V1/V2 region or the number of potential N-linked glycosylation sites in conserved regions of gp120. No correlation was found between the coreceptor usage and neutralization susceptibility of the virus to T-20, whereas several dual-tropic viruses showed higher susceptibility to coreceptor antagonists than CXCR4- or CCR5-tropic viruses. We propose that these CRF01_AE Env-recombinant viruses are useful to further study the molecular mechanism of the susceptibility of CRF01_AE Env to neutralizing antibodies and viral entry inhibitors.