RESUMEN
Combinational antiretroviral therapy (cART) suppresses human immunodeficiency virus type 1 (HIV-1) viral replication and pathogenesis in acquired immunodeficiency syndrome (AIDS) patients. However, HIV-1 remains in the latent stage of infection by suppressing viral transcription, which hinders an HIV-1 cure. One approach for an HIV-1 cure is the "shock and kill" strategy. The strategy focuses on reactivating latent HIV-1, inducing the viral cytopathic effect and facilitating the immune clearance for the elimination of latent HIV-1 reservoirs. Here, we reported that the H3K4 trimethylation (H3K4me3)-specific demethylase KDM5A/B play a role in suppressing HIV-1 Tat/LTR-mediated viral transcription in HIV-1 latent cells. Furthermore, we evaluated the potential of KDM5-specific inhibitor JQKD82 as an HIV-1 "shock and kill" agent. Our results showed that JQKD82 increases the H3K4me3 level at HIV-1 5' LTR promoter regions, HIV-1 reactivation, and the cytopathic effects in an HIV-1-latent T cell model. In addition, we identified that the combination of JQKD82 and AZD5582, a non-canonical NF-κB activator, generates a synergistic impact on inducing HIV-1 lytic reactivation and cell death in the T cell. The latency-reversing potency of the JQKD82 and AZD5582 pair was also confirmed in peripheral blood mononuclear cells (PBMCs) isolated from HIV-1 aviremic patients and in an HIV-1 latent monocyte. In latently infected microglia (HC69) of the brain, either deletion or inhibition of KDM5A/B results in a reversal of the HIV-1 latency. Overall, we concluded that KDM5A/B function as a host repressor of the HIV-1 lytic reactivation and thus promote the latency and the survival of HIV-1 infected reservoirs.
Asunto(s)
Infecciones por VIH , VIH-1 , Activación Viral , Latencia del Virus , VIH-1/fisiología , VIH-1/efectos de los fármacos , VIH-1/genética , Humanos , Latencia del Virus/efectos de los fármacos , Infecciones por VIH/virología , Infecciones por VIH/tratamiento farmacológico , Activación Viral/efectos de los fármacos , Proteína 2 de Unión a Retinoblastoma/metabolismo , Proteína 2 de Unión a Retinoblastoma/genética , Infección Latente/virología , Replicación Viral/efectos de los fármacos , Duplicado del Terminal Largo de VIH/genética , Supervivencia Celular , Línea Celular , Histonas/metabolismo , Proteínas Nucleares , Proteínas Represoras , Histona Demetilasas con Dominio de JumonjiRESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to NF-κB activation and induction of pro-inflammatory cytokines, though the underlying mechanism for this activation is not fully understood. Our results reveal that the SARS-CoV-2 Nsp14 protein contributes to the viral activation of NF-κB signaling. Nsp14 caused the nuclear translocation of NF-κB p65. Nsp14 induced the upregulation of IL-6 and IL-8, which also occurred in SARS-CoV-2 infected cells. IL-8 upregulation was further confirmed in lung tissue samples from COVID-19 patients. A previous proteomic screen identified the putative interaction of Nsp14 with host Inosine-5'-monophosphate dehydrogenase 2 (IMPDH2), which is known to regulate NF-κB signaling. We confirmed the Nsp14-IMPDH2 protein interaction and identified that IMPDH2 knockdown or chemical inhibition using ribavirin (RIB) and mycophenolic acid (MPA) abolishes Nsp14- mediated NF-κB activation and cytokine induction. Furthermore, IMPDH2 inhibitors (RIB, MPA) or NF-κB inhibitors (bortezomib, BAY 11-7082) restricted SARS-CoV-2 infection, indicating that IMPDH2-mediated activation of NF-κB signaling is beneficial to viral replication. Overall, our results identify a novel role of SARS-CoV-2 Nsp14 in inducing NF-κB activation through IMPDH2 to promote viral infection.
Asunto(s)
COVID-19 , Exorribonucleasas , IMP Deshidrogenasa , FN-kappa B , Proteínas no Estructurales Virales , Bortezomib , Citocinas/metabolismo , Exorribonucleasas/metabolismo , Humanos , IMP Deshidrogenasa/metabolismo , Inosina , Interleucina-6 , Interleucina-8 , Ácido Micofenólico , FN-kappa B/metabolismo , Oxidorreductasas , Proteómica , Ribavirina , SARS-CoV-2 , Proteínas no Estructurales Virales/metabolismoRESUMEN
FACT (FAcilitates Chromatin Transcription) is a heterodimeric protein complex composed of SUPT16H and SSRP1, and a histone chaperone participating in chromatin remodeling during gene transcription. FACT complex is profoundly regulated, and contributes to both gene activation and suppression. Here we reported that SUPT16H, a subunit of FACT, is acetylated in both epithelial and natural killer (NK) cells. The histone acetyltransferase TIP60 contributes to the acetylation of SUPT16H middle domain (MD) at lysine 674 (K674). Such acetylation of SUPT16H is recognized by bromodomain protein BRD4, which promotes protein stability of SUPT16H in both epithelial and NK cells. We further demonstrated that SUPT16H-BRD4 associates with histone modification enzymes (HDAC1, EZH2), and further regulates their activation status and/or promoter association as well as affects the relevant histone marks (H3ac, H3K9me3 and H3K27me3). BRD4 is known to profoundly regulate interferon (IFN) signaling, while such function of SUPT16H has never been explored. Surprisingly, our results revealed that SUPT16H genetic knockdown via RNAi or pharmacological inhibition by using its inhibitor, curaxin 137 (CBL0137), results in the induction of IFNs and interferon-stimulated genes (ISGs). Through this mechanism, depletion or inhibition of SUPT16H is shown to efficiently inhibit infection of multiple viruses, including Zika, influenza, and SARS-CoV-2. Furthermore, we demonstrated that depletion or inhibition of SUPT16H also causes the remarkable activation of IFN signaling in NK cells, which promotes the NK-mediated killing of virus-infected cells in a co-culture system using human primary NK cells. Overall, our studies unraveled the previously un-appreciated role of FACT complex in coordinating with BRD4 and regulating IFN signaling in both epithelial and NK cells, and also proposed the novel application of the FACT inhibitor CBL0137 to treat viral infections.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Células Epiteliales/metabolismo , Interferones/metabolismo , Células Asesinas Naturales/metabolismo , Transducción de Señal , Factores de Transcripción/metabolismo , COVID-19 , Proteínas de Unión al ADN/genética , Células Epiteliales/inmunología , Proteínas del Grupo de Alta Movilidad/genética , Humanos , Células Asesinas Naturales/inmunología , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , SARS-CoV-2 , Factores de Elongación Transcripcional/genética , Virus Zika/metabolismo , Infección por el Virus ZikaRESUMEN
Polyamines are critical metabolites involved in various cellular processes and often dysregulated in cancers. Kaposi's sarcoma-associated Herpesvirus (KSHV), a defined human oncogenic virus, leads to profound alterations of host metabolic landscape to favor development of KSHV-associated malignancies. In our studies, we identified that polyamine biosynthesis and eIF5A hypusination are dynamically regulated by KSHV infection through modulation of key enzymes (ODC1 and DHPS) of these pathways. During KSHV latency, ODC1 and DHPS are upregulated along with increase of hypusinated eIF5A (hyp-eIF5A), while hyp-eIF5A is further induced along with reduction of ODC1 and intracellular polyamines during KSHV lytic reactivation. In return these metabolic pathways are required for both KSHV lytic reactivation and de novo infection. Further analysis unraveled that synthesis of critical KSHV latent and lytic proteins (LANA, RTA) depends on hypusinated-eIF5A. We also demonstrated that KSHV infection can be efficiently and specifically suppressed by inhibitors targeting these pathways. Collectively, our results illustrated that the dynamic and profound interaction of a DNA tumor virus (KSHV) with host polyamine biosynthesis and eIF5A hypusination pathways promote viral propagation, thus defining new therapeutic targets to treat KSHV-associated malignancies.
Asunto(s)
Herpesvirus Humano 8 , Sarcoma de Kaposi , Regulación Viral de la Expresión Génica , Herpesvirus Humano 8/fisiología , Humanos , Poliaminas/metabolismo , Activación Viral/genética , Latencia del Virus/genética , Replicación ViralRESUMEN
Both Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV) establish the persistent, life-long infection primarily at the latent status, and associate with certain types of tumors, such as B cell lymphomas, especially in immuno-compromised individuals including people living with HIV (PLWH). Lytic reactivation of these viruses can be employed to kill tumor cells harboring latently infected viral episomes through the viral cytopathic effects and the subsequent antiviral immune responses. In this study, we identified that polo-like kinase 1 (PLK1) is induced by KSHV de novo infection as well as lytic switch from KSHV latency. We further demonstrated that PLK1 depletion or inhibition facilitates KSHV reactivation and promotes cell death of KSHV-infected lymphoma cells. Mechanistically, PLK1 regulates Myc that is critical to both maintenance of KSHV latency and support of cell survival, and preferentially affects the level of H3K27me3 inactive mark both globally and at certain loci of KSHV viral episomes. Furthremore, we recognized that PLK1 inhibition synergizes with STAT3 inhibition to efficiently induce KSHV reactivation. We also confirmed that PLK1 depletion or inhibition yields the similar effect on EBV lytic reactivation and cell death of EBV-infected lymphoma cells. Lastly, we noticed that PLK1 in B cells is elevated in the context of HIV infection and caused by HIV Nef protein to favor KSHV/EBV latency.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Infecciones por Herpesviridae/metabolismo , Herpesvirus Humano 8/fisiología , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Activación Viral/fisiología , Latencia del Virus/fisiología , Línea Celular , Infecciones por Virus de Epstein-Barr , Infecciones por VIH , Humanos , Quinasa Tipo Polo 1RESUMEN
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to NF-κB activation and induction of pro-inflammatory cytokines, though the underlying mechanism for this activation is not fully understood. Our results reveal that the SARS-CoV-2 Nsp14 protein contributes to the viral activation of NF-κB signaling. Nsp14 caused the nuclear translocation of NF-κB p65. Nsp14 induced the upregulation of IL-6 and IL-8, which also occurred in SARS-CoV-2 infected cells. IL-8 upregulation was further confirmed in lung tissue samples from COVID-19 patients. A previous proteomic screen identified the putative interaction of Nsp14 with host Inosine-5'-monophosphate dehydrogenase 2 (IMPDH2) protein, which is known to regulate NF-κB signaling. We confirmed the Nsp14-IMPDH2 protein interaction and found that IMPDH2 knockdown or chemical inhibition using ribavirin (RIB) and mycophenolic acid (MPA) abolishes Nsp14-mediated NF-κB activation and cytokine induction. Furthermore, IMDPH2 inhibitors (RIB, MPA) efficiently blocked SARS-CoV-2 infection, indicating that IMDPH2, and possibly NF-κB signaling, is beneficial to viral replication. Overall, our results identify a novel role of SARS-CoV-2 Nsp14 in causing the activation of NF-κB.
RESUMEN
FACT ( FA cilitates C hromatin T ranscription) is a heterodimeric protein complex composed of SUPT16H and SSRP1, and a histone chaperone participating in chromatin remodeling during gene transcription. FACT complex is profoundly regulated, and contributes to both gene activation and suppression. Here we reported that SUPT16H, a subunit of FACT, is acetylated at lysine 674 (K674) of middle domain (MD), which involves TIP60 histone acetyltransferase. Such acetylation of SUPT16H is recognized by bromodomain protein BRD4, which promotes protein stability of SUPT16H. We further demonstrated that SUPT16H-BRD4 associates with histone modification enzymes (EZH2, HDAC1) and affects histone marks (H3K9me3, H3K27me3 and H3ac). BRD4 is known to profoundly regulate interferon (IFN) signaling, while such function of SUPT16H has never been explored. Surprisingly, our results revealed that SUPT16H genetic knockdown via RNAi or pharmacological inhibition by using its inhibitor, curaxin 137 (CBL0137), results in the induction of IFNs and interferon-stimulated genes (ISGs). Through this mechanism, CBL0137 is shown to efficiently inhibit infection of multiple viruses, including Zika, influenza, and SARS-CoV-2. Furthermore, we demonstrated that CBL0137 also causes the remarkable activation of IFN signaling in natural killer (NK) cells, which promotes the NK-mediated killing of virus-infected cells in a co-culture system using human primary NK cells. Overall, our studies unraveled the previously un-appreciated role of FACT complex in regulating IFN signaling in both epithelial and NK cells, and also proposed the novel application of CBL0137 to treat viral infections.
RESUMEN
EBV-associated gastric cancer (EBVaGC) is characterized by high frequency of DNA methylation. In this study, we investigated how epigenetic alteration of host genome contributes to pathogenesis of EBVaGC through the analysis of transcriptomic and epigenomic datasets from NIH TCGA (The Cancer Genome Atlas) consortium. We identified that immune related genes (IRGs) is a group of host genes preferentially silenced in EBV-positive gastric cancers through DNA hypermethylation. Further functional characterizations of selected IRGs reveal their novel antiviral activity against not only EBV but also KSHV. In particular, we showed that metallothionein-1 (MT1) and homeobox A (HOXA) gene clusters are down-regulated via EBV-driven DNA hypermethylation. Several MT1 isoforms suppress EBV lytic replication and release of progeny virions as well as KSHV lytic reactivation, suggesting functional redundancy of these genes. In addition, single HOXA10 isoform exerts antiviral activity against both EBV and KSHV. We also confirmed the antiviral effect of other dysregulated IRGs, such as IRAK2 and MAL, in scenario of EBV and KSHV lytic reactivation. Collectively, our results demonstrated that epigenetic silencing of IRGs is a viral strategy to escape immune surveillance and promote viral propagation, which is overall beneficial to viral oncogenesis of human gamma-herpesviruses (EBV and KSHV), considering that these IRGs possess antiviral activities against these oncoviruses.
Asunto(s)
Biomarcadores/metabolismo , Epigénesis Genética , Gammaherpesvirinae/aislamiento & purificación , Regulación Viral de la Expresión Génica , Infecciones por Herpesviridae/complicaciones , Interacciones Huésped-Patógeno , Neoplasias Gástricas/genética , Biomarcadores/análisis , Metilación de ADN , Gammaherpesvirinae/genética , Células HEK293 , Infecciones por Herpesviridae/virología , Proteínas Homeobox A10/genética , Humanos , Incidencia , Metalotioneína/genética , Neoplasias Gástricas/epidemiología , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/virología , Activación Viral , Replicación ViralRESUMEN
Although combination antiretroviral therapy is effective in controlling HIV-1 infection, latent HIV-1 proviruses cannot be eliminated. HIV-1 reactivation induced by the mere use of latency-reversing agents is insufficient to render death of reservoir cells, indicating that certain intrinsic survival mechanisms exist. We report that Polo-like kinase 1 (PLK1) plays a critical role in survival of CD4+ T cells that undergo HIV-1 reactivation from latency or de novo infection. PLK1 is elevated in both scenarios, which requires HIV-1 Nef. HIV-1 enhances PLK1 SUMOylation, causing its nuclear translocation and protein stabilization. Inhibition or knockdown of PLK1 markedly facilitates death of HIV-1-infected CD4+ T cells. Furthermore, PLK1 inhibitors strikingly reduce the size of HIV-1 latent reservoirs in primary CD4+ T cells. Our findings demonstrate that HIV-1 infection hijacks PLK1 to prevent cell death induced by viral cytopathic effects, and that PLK1 is a promising target for chemical "killing" of HIV-1 reservoir cells.
Asunto(s)
Linfocitos T CD4-Positivos , Proteínas de Ciclo Celular , Infecciones por VIH , Proteínas Serina-Treonina Quinasas , Proteínas Proto-Oncogénicas , Linfocitos T CD4-Positivos/metabolismo , Linfocitos T CD4-Positivos/virología , Proteínas de Ciclo Celular/antagonistas & inhibidores , Proteínas de Ciclo Celular/metabolismo , VIH-1/fisiología , Humanos , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Proteínas Proto-Oncogénicas/metabolismo , Activación Viral , Latencia del Virus , Quinasa Tipo Polo 1RESUMEN
Recent efforts have been paid to identify previously unrecognized HIV-1 latency-promoting genes (LPGs) that can potentially be targeted for eradication of HIV-1 latent reservoirs. From our earlier orthologous RNAi screens of host factors regulating HIV-1 replication, we identified that the nucleolar protein NOP2/NSUN1, a m5C RNA methyltransferase (MTase), is an HIV-1 restriction factor. Loss- and gain-of-function analyses confirmed that NOP2 restricts HIV-1 replication. Depletion of NOP2 promotes the reactivation of latently infected HIV-1 proviruses in multiple cell lines as well as primary CD4+ T cells, alone or in combination with latency-reversing agents (LRAs). Mechanistically, NOP2 associates with HIV-1 5' LTR, interacts with HIV-1 TAR RNA by competing with HIV-1 Tat protein, as well as contributes to TAR m5C methylation. RNA MTase catalytic domain (MTD) of NOP2 mediates its competition with Tat and binding with TAR. Overall, these findings verified that NOP2 suppresses HIV-1 transcription and promotes viral latency.
Asunto(s)
Metilación de ADN , ADN Viral/metabolismo , Duplicado del Terminal Largo de VIH , VIH-1/fisiología , Proteínas Nucleares/metabolismo , ARN Viral/metabolismo , Transcripción Genética , Latencia del Virus/fisiología , ARNt Metiltransferasas/metabolismo , Productos del Gen tat del Virus de la Inmunodeficiencia Humana/metabolismo , Humanos , Células JurkatRESUMEN
Proteins usually associate with other molecules physically to execute their functions. Identifying these interactions is important for the functional analysis of proteins. Previously, we reported the parallel analysis of translated ORFs (PLATO) to couple ribosome display of full-length ORFs with affinity enrichment of mRNA/protein/ribosome complexes for the "bait" molecules, followed by the deep sequencing analysis of mRNA. However, the sample processing, from extraction of precipitated mRNA to generation of DNA libraries, includes numerous steps, which is tedious and may cause the loss of materials. Barcoded PLATO (PLATO-BC), an improved platform was further developed to test its application for protein interaction discovery. In this report, we tested the antisera-antigen interaction using serum samples from patients with inclusion body myositis (IBM). Tripartite motif containing 21 (TRIM21) was identified as a potentially new IBM autoantigen. We also expanded the application of PLATO-BC to identify protein interactions for JQ1, single ubiquitin peptide, and NS5 protein of Zika virus. From PLATO-BC analyses, we identified new protein interactions for these "bait" molecules. We demonstrate that Ewing sarcoma breakpoint region 1 (EWSR1) binds to JQ1 and their interactions may interrupt the EWSR1 association with acetylated histone H4. RIO kinase 3 (RIOK3), a newly identified ubiquitin-binding protein, is preferentially associated with K63-ubiquitin chain. We also find that Zika NS5 protein interacts with two previously unreported host proteins, par-3 family cell polarity regulator (PARD3) and chromosome 19 open reading frame 53 (C19orf53), whose attenuated expression benefits the replication of Zika virus. These results further demonstrate that PLATO-BC is capable of identifying novel protein interactions for various types of "bait" molecules.
Asunto(s)
Sistemas de Lectura Abierta/genética , Mapeo de Interacción de Proteínas/métodos , Anticuerpos/metabolismo , Células HEK293 , Humanos , Péptidos/metabolismo , Unión Proteica , Ubiquitina/metabolismo , Virus Zika/fisiología , Infección por el Virus Zika/genética , Infección por el Virus Zika/virologíaRESUMEN
Although combination antiretroviral therapy is potent to block active replication of HIV-1 in AIDS patients, HIV-1 persists as transcriptionally inactive proviruses in infected cells. These HIV-1 latent reservoirs remain a major obstacle for clearance of HIV-1. Investigation of host factors regulating HIV-1 latency is critical for developing novel antiretroviral reagents to eliminate HIV-1 latent reservoirs. From our recently accomplished CRISPR/Cas9 sgRNA screens, we identified that the histone demethylase, MINA53, is potentially a novel HIV-1 latency-promoting gene (LPG). We next validated MINA53's function in maintenance of HIV-1 latency by depleting MINA53 using the alternative RNAi approach. We further identified that in vitro MINA53 preferentially demethylates the histone substrate, H3K36me3 and that in cells MINA53 depletion by RNAi also increases the local level of H3K36me3 at LTR. The effort to map the downstream effectors unraveled that H3K36me3 has the cross-talk with another epigenetic mark H4K16ac, mediated by KAT8 that recognizes the methylated H3K36 and acetylated H4K16. Removing the MINA53-mediated latency mechanisms could benefit the reversal of post-integrated latent HIV-1 proviruses for purging of reservoir cells. We further demonstrated that a pan jumonji histone demethylase inhibitor, JIB-04, inhibits MINA53-mediated demethylation of H3K36me3, and JIB-04 synergizes with other latency-reversing agents (LRAs) to reactivate latent HIV-1.
Asunto(s)
Sistemas CRISPR-Cas , Dioxigenasas/genética , Infecciones por VIH/genética , VIH-1/genética , Histona Demetilasas/genética , Proteínas Nucleares/genética , Latencia del Virus/genética , Aminopiridinas/farmacología , Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD4-Positivos/metabolismo , Linfocitos T CD4-Positivos/virología , Línea Celular Tumoral , Células Cultivadas , Desmetilación/efectos de los fármacos , Dioxigenasas/antagonistas & inhibidores , Dioxigenasas/metabolismo , Regulación Viral de la Expresión Génica/efectos de los fármacos , Células HEK293 , Infecciones por VIH/metabolismo , Infecciones por VIH/virología , VIH-1/efectos de los fármacos , VIH-1/fisiología , Inhibidores de Histona Desacetilasas/farmacología , Histona Demetilasas/antagonistas & inhibidores , Histona Demetilasas/metabolismo , Histonas/metabolismo , Interacciones Huésped-Patógeno/efectos de los fármacos , Interacciones Huésped-Patógeno/genética , Humanos , Hidrazonas/farmacología , Metilación/efectos de los fármacos , Proteínas Nucleares/antagonistas & inhibidores , Proteínas Nucleares/metabolismo , Interferencia de ARNRESUMEN
A cure for human immunodeficiency virus type-1 (HIV-1) has been hampered by the limitation of current combination antiretroviral therapy (cART) to address the latent reservoirs in HIV-1 patients. One strategy proposed to eradicate these reservoirs is the "shock and kill" approach, where latency-reversing agents (LRAs) are used to reactivate and promote viral cell death and/or immune killing of reactivated cells. Here, we report that curaxin CBL0137, an antitumor compound, can potentiate tumor necrosis factor-α-mediated reactivation of latently infected HIV-1cell lines. Additionally, the single use of CBL0137 is sufficient to reactivate HIV-1 latent reservoirs in peripheral mononuclear cells (PBMCs) isolated from HIV-1 positive, cART-treated, aviremic patients. Thus, CBL0137 possesses capabilities as a LRA and could be considered for the "shock and kill" approach.
Asunto(s)
Carbazoles/farmacología , Infecciones por VIH/virología , VIH-1/fisiología , Activación Viral/efectos de los fármacos , Latencia del Virus , Células Cultivadas , Humanos , Leucocitos Mononucleares/efectos de los fármacos , Leucocitos Mononucleares/virología , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Since the implementation of combination antiretroviral therapy (cART), rates of HIV type 1 (HIV-1) mortality, morbidity, and newly acquired infections have decreased dramatically. In fact, HIV-1-infected individuals under effective suppressive cART approach normal life span and quality of life. However, long-term therapy is required because the virus establish a reversible state of latency in memory CD4+ T cells. Two principle strategies, namely "shock and kill" approach and "block and lock" approach, are currently being investigated for the eradication of these HIV-1 latent reservoirs. Actually, both of these contrasting approaches are based on the use of small-molecule compounds to achieve the cure for HIV-1. In this review, we discuss the recent progress that has been made in designing and developing small-molecule compounds for both strategies.
Asunto(s)
Antivirales/farmacología , Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD4-Positivos/virología , Infecciones por VIH/tratamiento farmacológico , VIH-1/efectos de los fármacos , Interacciones Huésped-Patógeno/efectos de los fármacos , Latencia del Virus/efectos de los fármacos , Investigación Biomédica/tendencias , Descubrimiento de Drogas/tendencias , HumanosRESUMEN
Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic virus responsible for the development of Kaposi's sarcoma, primary effusion lymphoma (PEL), and Multicentric Castleman's disease in immunocompromised individuals. Despite the burden of these diseases there are few treatment options for afflicted individuals, due in part to our limited understanding of virus-host interactions. Tip60, a histone aceytltransferase (HAT) has been previously shown to interact with both the KSHV latency associated nuclear antigen protein (LANA), which is the main factor in maintaining the viral latent state, and ORF36, a viral kinase expressed in the lytic phase. We further investigated Tip60-virus interaction to ascertain Tip60's role in the viral life cycle and its potential as a target for future therapeutics. Through modulation of Tip60 expression in HEK293T cells harboring a plasmid containing the KSHV viral episome, Bac36, we found that Tip60 is vital for both lytic replication as well as efficient expression of latent genes. Interestingly, Tip60 small molecule inhibitors, MG149 and NU9056, similarly inhibited latent and lytic genes, and reduced virion production in wild-type KSHV+/EBV- PEL, BCBL-1 cells. Long-term treatment with these Tip60 inhibitors selectively decreased the viability of KSHV-infected B lymphoma cells compared to uninfected cells. From this study, we conclude that Tip60 is important for KSHV infection and its associated cancer development, and Tip60 is therefore a potential target for future antiviral and anticancer therapeutics.
RESUMEN
The spatiotemporal dynamics of Hepatitis C Virus (HCV) RNA localisation are poorly understood. To address this we engineered HCV genomes harbouring MS2 bacteriophage RNA stem-loops within the 3'-untranslated region to allow tracking of HCV RNA via specific interaction with a MS2-Coat-mCherry fusion protein. Despite the impact of these insertions on viral fitness, live imaging revealed that replication of tagged-HCV genomes induced specific redistribution of the mCherry-tagged-MS2-Coat protein to motile and static foci. Further analysis showed that HCV RNA was associated with NS5A in both static and motile structures while a subset of motile NS5A structures was devoid of HCV RNA. Further investigation of viral RNA traffic with respect to lipid droplets (LDs) revealed HCV RNA-positive structures in close association with LDs. These studies provide new insights into the dynamics of HCV RNA traffic with NS5A and LDs and provide a platform for future investigations of HCV replication and assembly.
Asunto(s)
Hepacivirus/metabolismo , ARN Viral/metabolismo , Proteínas no Estructurales Virales/metabolismo , Línea Celular , Citoplasma/virología , Hepacivirus/genética , Secuencias Invertidas Repetidas , Replicación ViralRESUMEN
UNLABELLED: Hepatitis C virus (HCV) NS5A is essential for viral genome replication within cytoplasmic replication complexes and virus assembly at the lipid droplet (LD) surface, although its definitive functions are poorly understood. We developed approaches to investigate NS5A dynamics during a productive infection. We report here that NS5A motility and efficient HCV RNA replication require the microtubule network and the cytoplasmic motor dynein and demonstrate that both motile and relatively static NS5A-positive foci are enriched with host factors VAP-A and Rab5A. Pulse-chase imaging revealed that newly synthesized NS5A foci are small and distinct from aged foci, while further studies using a unique dual fluorescently tagged infectious HCV chimera showed a relatively stable association of NS5A foci with core-capped LDs. These results reveal new details about the dynamics and maturation of NS5A and the nature of potential sites of convergence of HCV replication and assembly pathways. IMPORTANCE: Hepatitis C virus (HCV) is a major cause of serious liver disease worldwide. An improved understanding of the HCV replication cycle will enable development of novel and improved antiviral strategies. Here we have developed complementary fluorescent labeling and imaging approaches to investigate the localization, traffic and interactions of the HCV NS5A protein in living, virus-producing cells. These studies reveal new details as to the traffic, composition and biogenesis of NS5A foci and the nature of their association with putative sites of virus assembly.
Asunto(s)
Hepacivirus/inmunología , Proteínas no Estructurales Virales/análisis , Ensamble de Virus , Replicación Viral , Línea Celular , Dineínas/metabolismo , Hepatocitos/química , Hepatocitos/virología , Humanos , Microtúbulos/metabolismo , Proteínas de Transporte Vesicular/análisis , Proteínas de Unión al GTP rab5/análisisRESUMEN
The host protein viperin is an interferon stimulated gene (ISG) that is up-regulated during a number of viral infections. In this study we have shown that dengue virus type-2 (DENV-2) infection significantly induced viperin, co-incident with production of viral RNA and via a mechanism requiring retinoic acid-inducible gene I (RIG-I). Viperin did not inhibit DENV-2 entry but DENV-2 RNA and infectious virus release was inhibited in viperin expressing cells. Conversely, DENV-2 replicated to higher tires earlier in viperin shRNA expressing cells. The anti-DENV effect of viperin was mediated by residues within the C-terminal 17 amino acids of viperin and did not require the N-terminal residues, including the helix domain, leucine zipper and S-adenosylmethionine (SAM) motifs known to be involved in viperin intracellular membrane association. Viperin showed co-localisation with lipid droplet markers, and was co-localised and interacted with DENV-2 capsid (CA), NS3 and viral RNA. The ability of viperin to interact with DENV-2 NS3 was associated with its anti-viral activity, while co-localisation of viperin with lipid droplets was not. Thus, DENV-2 infection induces viperin which has anti-viral properties residing in the C-terminal region of the protein that act to restrict early DENV-2 RNA production/accumulation, potentially via interaction of viperin with DENV-2 NS3 and replication complexes. These anti-DENV-2 actions of viperin show both contrasts and similarities with other described anti-viral mechanisms of viperin action and highlight the diverse nature of this unique anti-viral host protein.
Asunto(s)
Virus del Dengue/patogenicidad , Dengue/metabolismo , Proteínas/metabolismo , Animales , Western Blotting , Línea Celular Tumoral , Chlorocebus aethiops , Dengue/genética , Dengue/virología , Humanos , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH , Proteínas/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Células VeroRESUMEN
UNLABELLED: The interferon-stimulated gene, viperin, has been shown to have antiviral activity against hepatitis C virus (HCV) in the context of the HCV replicon, although the molecular mechanisms responsible are not well understood. Here, we demonstrate that viperin plays an integral part in the ability of interferon to limit the replication of cell-culture-derived HCV (JFH-1) that accurately reflects the complete viral life cycle. Using confocal microscopy and fluorescence resonance energy transfer (FRET) analysis, we demonstrate that viperin localizes and interacts with HCV nonstructural protein 5A (NS5A) at the lipid-droplet (LD) interface. In addition, viperin also associates with NS5A and the proviral cellular factor, human vesicle-associated membrane protein-associated protein subtype A (VAP-A), at the HCV replication complex. The ability of viperin to limit HCV replication was dependent on residues within the C-terminus, as well as an N-terminal amphipathic helix. Removal of the amphipathic helix-redirected viperin from the cytosolic face of the endoplasmic reticulum and the LD to a homogenous cytoplasmic distribution, coinciding with a loss of antiviral effect. C-terminal viperin mutants still localized to the LD interface and replication complexes, but did not interact with NS5A proteins, as determined by FRET analysis. CONCLUSION: In conclusion, we propose that viperin interacts with NS5A and the host factor, VAP-A, to limit HCV replication at the replication complex. This highlights the complexity of the host control of viral replication by interferon-stimulated gene expression.