RESUMO
Zika virus (ZIKV) is a globally transmitted mosquito-borne pathogen, and no effective treatment or vaccine is available yet. Lipophagy, a selective autophagy targeting lipid droplets (LDs), is an emerging subject in cellular lipid metabolism and energy homeostasis. However, the regulatory mechanism of lipid metabolism and the role of lipophagy in Zika virus infection remain largely unknown. Here, we demonstrated that ZIKV induced lipophagy by activating unc-51-like kinase 1 (ULK1) through activation of 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK) in Huh7 cells. Upon ZIKV infection, the average size and triglyceride content of LDs significantly decreased. Moreover, ZIKV infection significantly increased lysosomal biosynthesis and LD-lysosome fusion. The activities of AMPK at Thr-172 and ULK1 at Ser-556 were increased in ZIKV-infected cells and closely correlated with lipophagy induction. Silencing of AMPK expression inhibited ZIKV infection, autophagy induction, and LD-lysosome fusion and decreased the triglyceride content of the cells. The activities of mammalian target of rapamycin (mTOR) at Ser-2448 and ULK1 at Ser-757 were suppressed independently of AMPK during ZIKV infection. Therefore, ZIKV infection triggers AMPK-mediated lipophagy, and the LD-related lipid metabolism during ZIKV infection is mainly regulated via the AMPK-ULK1 signaling pathway.
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Infecção por Zika virus , Zika virus , Humanos , Animais , Proteínas Quinases Ativadas por AMP/metabolismo , Autofagia/fisiologia , Transdução de Sinais , Triglicerídeos , Mamíferos/metabolismo , Proteína Homóloga à Proteína-1 Relacionada à Autofagia/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismoRESUMO
Lipid droplets (LDs) are highly conserved and dynamic intracellular organelles. Their functions are not limited to serving as neutral lipid reservoirs; they also participate in non-energy storage functions, such as cell lipid metabolism, protection from cell stresses, maintaining protein homeostasis, and regulating nuclear function. During a Zika virus (ZIKV) infection, the viruses hijack the LDs to provide energy and lipid sources for viral replication. The co-localization of ZIKV capsid (C) protein with LDs supports its role as a virus replication platform and a key compartment for promoting the generation of progeny virus particles. However, in view of the multiple functions of LDs, their role in ZIKV infection needs further elucidation. Here, we review the basic mechanism of LD biogenesis and biological functions and discuss how ZIKV infection utilizes these effects of LDs to facilitate virus replication, along with the future application strategy of developing new antiviral drugs based on the interaction of ZIKV with LDs.
Assuntos
Infecção por Zika virus , Zika virus , Humanos , Zika virus/metabolismo , Gotículas Lipídicas/metabolismo , Replicação Viral , Metabolismo dos Lipídeos , Lipídeos , Antivirais/metabolismoRESUMO
Hepatitis C virus (HCV) infection affects approximately 1% of the world's population and is a major cause of chronic liver diseases. Although antiviral therapy consisting of direct-acting antivirals (DAAs) can cure the majority of HCV patients, it is still limited by viral resistances, drug-drug interactions, and high costs. Moreover, the role of DAAs in the prevention of occurrences of graft reinfection in HCV patients who receive liver transplantations is still under comprehensive clinical investigation, bringing the risk of recipient reinfection. HCV entry is composed of initial non-specific attachment and binding, post-binding interactions with essential host factors, internalization, and virion-cell membrane fusion to release viral RNA to cytosol. Thus, a number of novel and promising targets from either virion or cellular factors of these processes become optimal interfering elements for antiviral therapy, eliminating viral infection at the very beginning. Therefore, entry inhibitors can be supplemented into the future treatment regimens to optimize and widen the prevention and therapeutics of HCV infection. This chapter introduces the basic HCV entry processes and summarizes molecular mechanisms and research status of the current antiviral agents targeting HCV entry in preclinical and clinical study.
Assuntos
Hepatite C Crônica , Hepatite C , Antivirais/química , Antivirais/farmacologia , Antivirais/uso terapêutico , Hepacivirus/genética , Hepatite C/tratamento farmacológico , Hepatite C Crônica/tratamento farmacológico , Humanos , Reinfecção , Internalização do VírusRESUMO
Dengue virus (DENV) is an arthropod-borne viral pathogen and a global health burden. Knowledge of the DENV-host interactions that mediate virus pathogenicity remains limited. Host lipid metabolism is hijacked by DENV for virus replication in which lipid droplets (LDs) play a key role during the virus lifecycle. In this study, we reveal a novel role for phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in LDs-mediated DENV infection. We demonstrate that PTEN expression is downregulated upon DENV infection through post-transcriptional regulation and, in turn, PTEN overexpression enhances DENV replication. PTEN lipid phosphatase activity was found to decrease cellular LDs area and number through Akt/FoxO1/Maf1 signaling, which, together with autophagy, enhanced DENV replication and virus production. We therefore provide mechanistic insight into the interaction between lipid metabolism and the DENV replication cycle.
Assuntos
Vírus da Dengue , Dengue , Criança , Proteína Forkhead Box O1/genética , Humanos , Lipídeos , Pessoa de Meia-Idade , PTEN Fosfo-Hidrolase/genética , Fosfatidilinositol 3-Quinases , Proteínas Proto-Oncogênicas c-akt , Transdução de Sinais , Replicação ViralRESUMO
Non-alcoholic fatty liver disease (NAFLD) associated with obesity may progress to non-alcoholic steatohepatitis, cirrhosis and hepatocellular carcinoma (HCC). Retinoic acid induced 16 (RAI16) plays an important role in cell apoptosis and is also a potential marker for HCC. Here we aimed to test the effect of RAI16 deficiency on liver pathology in high-fat diet (HFD) fed mice. Wild type (WT) and RAI16 knockout (RAI16-/-) C57BL/6 mice were fed with HFD or chow for up to 12 months. With consumption of HFD diet, RAI16-/- mice on HFD developed much more excess fatty liver within 4 months than WT mice on HFD. The expressions of fatty acid synthesis associated molecules Ppar-γ, Srebp-1c and Fas were further increased in RAI16-/- mice compared with WT mice on HFD. Macrophage infiltration related molecules Mcp-1 and F4/80 and pro-inflammatory factor Lcn2 were significantly increased in RAI16-/- mice compared with WT mice on HFD. Conclusively, RAI16 deficiency exacerbated HFD-induced liver injury, associated with increased inflammation. These findings indicate that RAI16 plays an important role in HFD-induced liver pathology and might be considered as a target for treatment of NAFLD. SIGNIFICANCE: 1. RAI16-/- mice on HFD developed much more excess fatty liver. 2. RAI16-/- mice showed more macrophage infiltration and proinflammation.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Hepatopatia Gordurosa não Alcoólica/genética , Animais , Apoptose , Quimiocina CCL2/metabolismo , Ácidos Graxos/metabolismo , Regulação da Expressão Gênica , Inflamação , Metabolismo dos Lipídeos , Lipocalina-2/metabolismo , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , ProteínasRESUMO
BACKGROUND: Retinoid acid induced 16 (RAI16) was reported to enhance tumorigenesis in hepatocellular carcinoma (HCC). The androgen receptor (AR) is a nuclear hormone receptor that functions as a critical oncogene in several cancer progressions. However, whether RAI16 is a candidate AR target gene that may involve in prostate cancer progression was unclear. MATERIALS & METHODS: RAI16 expression was detected in prostate cancer cells with or without the AR agonist R1881 treatment by quantitative RT-PCR and Western blot. Direct AR binding to the RAI16 promoter was tested using AR chromatin immunoprecipitation (ChIP) and luciferase assay. Cell viability and colony formation assays in response to R1881 were analyzed in cells with RAI16 knockdown by specific siRNA. RESULTS: The expression of RAI16 was high in LNCaP(AI), LNCaP(AD), C4-2 expressing AR, but low in Du145 and Pc-3 cells without AR expressing. In addition, the expression of RAI16 could be induced by 10 nM R1881 treatment LNCaP(AD) and C4-2 cells, but inhibited by AR specific siRNA treatment. Furthermore, AR binds directly to ARE3 (-2003~-1982bp) of RAI16 promoter region by ChIP and luciferase assay. RAI16 knockdown inhibited the enhancement of cell viability and colony formation of AR stimulation. CONCLUSIONS: We demonstrate for the first time that RAI16 is a direct target gene of AR. RAI16 may involved in cell growth of prostate cancer cells in response to AR signaling.
Assuntos
Adenocarcinoma/genética , Neoplasias da Próstata/genética , Proteínas/genética , Receptores Androgênicos/fisiologia , Adenocarcinoma/patologia , Androgênios/farmacologia , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Masculino , Metribolona/farmacologia , Células PC-3 , Regiões Promotoras Genéticas/efeitos dos fármacos , Neoplasias da Próstata/patologia , Ligação Proteica/efeitos dos fármacos , Proteínas/fisiologia , Receptores Androgênicos/metabolismoRESUMO
Inflammatory bowel disease (IBD) and colitis-associated colorectal cancer (CAC) is a serious health issue, but etiopathological factors remain unclear. Although some studies reported the roles of Retinoid acid induced 16 (RAI16) in the tumorigenesis of hepatocellular carcinoma and PKA signaling, the roles of RAI16 in IBD and CRC are undressed. RAI16-/- mice were generated and the roles of RAI16 were addressed in dextran sodium sulfate (DSS) or azoxymethane (AOM)-DSS induced IBD or CAC mouse models, respectively. At first, RAI16-/- mice were viable, fertile with no apparent defects. Then, it was found that RAI16-/- mice were more susceptibility to colitis induced by DSS than wild type (WT) littermates, which was evaluated by disease activity index and histological score. Furthermore, the expressions of tissues repair associated molecules Cox2, Ereg and MMP-10 were significantly decreased in RAI16-/- colon under DSS treatment. Gut barrier related genes including antimicrobial peptides Reg3b and Reg3g and intestinal mucus genes Muc4, Muc6 and Muc20 were reduced in RAI16-/- colon. These findings indicated that RAI16 may function to affect genes involved in intestinal barrier function and immunoprotective inflammation. Accordingly, RAI16-/- mice displayed significantly increased tumor burden compared with WT mice assessed in CAC model induced by AOM/DSS. Much more Ki67 + nuclei were observed in RAI16-/- tumors suggesting RAI16 to be critical in colonic cell proliferation during tumorigenesis. Conclusively, we demonstrate the roles of RAI16 in colonic inflammation and inflammation-associated tumorigenesis by using a novel RAI16-/- mouse model for the first time.
Assuntos
Carcinoma Hepatocelular/genética , Colite/genética , Doenças Inflamatórias Intestinais/genética , Neoplasias Hepáticas/genética , Proteínas/genética , Animais , Carcinogênese/genética , Carcinoma Hepatocelular/etiologia , Carcinoma Hepatocelular/patologia , Transformação Celular Neoplásica/efeitos dos fármacos , Transformação Celular Neoplásica/genética , Colite/induzido quimicamente , Colite/complicações , Colite/patologia , Colo/efeitos dos fármacos , Colo/patologia , Neoplasias Colorretais/etiologia , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Sulfato de Dextrana/toxicidade , Modelos Animais de Doenças , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Inflamação/induzido quimicamente , Inflamação/complicações , Inflamação/genética , Inflamação/patologia , Doenças Inflamatórias Intestinais/induzido quimicamente , Doenças Inflamatórias Intestinais/complicações , Doenças Inflamatórias Intestinais/patologia , Mucosa Intestinal/efeitos dos fármacos , Neoplasias Hepáticas/etiologia , Neoplasias Hepáticas/patologia , Camundongos , Proteínas de Neoplasias/genética , Transdução de SinaisRESUMO
Enterovirus 71 (EV71) is typically transmitted by the oral-faecal route and initiates infection upon crossing the intestinal mucosa. Our limited understanding of the mechanisms by which it crosses the intestinal mucosa has hampered the development of effective therapeutic options. Here, using an RNA interference screen combined with chemical inhibitors or the overexpression of dominant negative proteins, we found that EV71 entry into Caco-2 cells, a polarized human intestinal epithelial cell line, does not involve clathrin- and caveolae-dependent endocytic pathways or macropinocytosis but requires GTP-binding protein dynamin 2 and cytoskeleton remodelling. The use of siRNAs targeting endophilin family members revealed that endophlin-A2 is essential for the uptake of EV71 particles by Caco-2 cells. Subcellular analysis revealed that internalized EV71 virions largely colocalized with endophilin-A2 at cytomembrane ruffles and in the perinuclear area. Combined with viral entry kinetics, these data suggest that EV71 enters Caco-2 cells mainly via an endophilin-A2-mediated endocytic (EME) pathway. Finally, we showed that internalized EV71 virions were transported to endosomal sorting complex required for transport (ESCRT)-related multivesicular bodies (MVBs). These data provide attractive therapeutic targets to block EV71 infection.
Assuntos
Endocitose , Enterovirus Humano A/fisiologia , Infecções por Enterovirus/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Internalização do Vírus , Células CACO-2 , Enterovirus Humano A/genética , Infecções por Enterovirus/virologia , Células Epiteliais/metabolismo , Células Epiteliais/virologia , Humanos , Mucosa Intestinal/virologia , Peptídeos e Proteínas de Sinalização Intracelular/genéticaRESUMO
AIM: To study the effect of discoidin I-like domaincontaining protein 3 (EDIL3) depletion on the proliferation and epithelial-mesenchymal transition (EMT) in human lens epithelial cells (LECs). METHODS: RNA interference was used to inhibit the expression of EDIL3 in human LECs in vitro. The morphology of cells was observed using an inverted microscope. Cell proliferation was assessed using EdU kit. Cell migration was investigated using Transwell chamber and EMT of LECs was assessed using confocal microscope and Western blotting. The transforming growth factor ß (TGFß) pathway was investigated using Western blotting. RESULTS: The data showed that silencing EDIL3 expression changed LECs morphology and suppressed LECs proliferation (P<0.05) and migration (P<0.01). Furthermore, the result of Western blotting showed that EDIL3 depletion reduced the expression of α-smooth muscle actin (α-SMA) (P<0.001) and vimentin (P<0.01), while increased the expression of E-cadherin (P<0.001). EDIL3 depletion could suppress the phosphorylation of Smad2 (P<0.01) and Smad3 (P<0.01) and the activation of exracellular signal regulated kinase (ERK) (P<0.05). CONCLUSION: The findings indicate that EDIL3 might participate in the proliferation and EMT in LECs via TGFß pathway and may be a potential therapeutic target for the treatment of posterior capsule opacification.
RESUMO
Influenza H7N9 virus infection causes an acute, highly contagious respiratory illness that triggers cell death of infected cells and airway epithelial destruction. RIP3 is a key regulator of cell death responses to a growing number of viral and microbial agents. This study aimed to investigate the role of RIP3 in inflammation of influenza H7N9 virus infection. Here, RIP3 knock out (RIP3-/-) mice and littermate wild type mice were infected intranasally with influenza H7N9 virus (A/Fujian/S03/2015) to determine the contribution of RIP3 to the inflammatory response of influenza H7N9 virus infection. It was found that RIP3-/- mice infected with H7N9 virus showed higher survival and less weight loss, compared with wild type littermate mice. In addition, RIP3-/- mice had fewer regions of edema, infiltration with inflammatory cells, and alvelolar collapses, and the secretions of IL-1ß, IL-6, RANTES and MIP-1 in BALF were significantly decreased on days 3 and 7 p.i. when compared with WT mice. Moreover, caspase 1/IL1ß signaling was found to be invovled in RIP3 associated imflammation of influenza H7N9 virus, but not RIP3/MLKL dependent necrosis. In the conclusion, our results indicated that RIP3 deficiency can protect mice from the infection of influenza H7N9 virus by downregulating caspase 1/IL1ß signaling, which provided edivence of the RIP3 invovled necroptosis independent manner.
Assuntos
Caspase 1/metabolismo , Citocinas/metabolismo , Subtipo H7N9 do Vírus da Influenza A/imunologia , Influenza Humana/imunologia , Proteína Serina-Treonina Quinases de Interação com Receptores/imunologia , Animais , Apoptose/imunologia , Líquido da Lavagem Broncoalveolar/imunologia , Caspase 1/imunologia , Citocinas/imunologia , Modelos Animais de Doenças , Regulação para Baixo , Humanos , Subtipo H7N9 do Vírus da Influenza A/patogenicidade , Influenza Humana/mortalidade , Influenza Humana/patologia , Influenza Humana/virologia , Pulmão/imunologia , Pulmão/patologia , Camundongos , Camundongos Knockout , Necrose/imunologia , Proteínas Quinases/imunologia , Proteínas Quinases/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/genética , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Transdução de Sinais , Redução de PesoRESUMO
Ulcerative colitis (UC) is a chronic intestinal inflammatory disease. The receptor-interacting protein kinase 3 (RIP3) was reported to be involved in many inflammatory disease. However, the mechanism of RIP3 in the pathogenesis of UC is still unclear. To investigate the effects and possible mechanism of RIP3 in UC pathogenesis, RIP3-/- mice was used in dextran sulfate sodium (DSS)-induced colitis model. It was found that by DSS-induced colitis, RIP3-/- mice showed significantly enhanced colitis symptoms, including increased weight loss, colon shortening, and colonic mucosa damage and severity, but decreased production of interleukin 6 and interleukin 1ß. The results showed that RIP3 deficiency could not ameliorate but exacerbate the severity of colitis. On the mechanism, it was found that messenger RNA expressions of several repair-associated cytokines including interleukin 6, interleukin 22, cyclooxygenase 2, epithelial growth factor receptor ligand Epiregulin and matrix metalloproteinase 10 were siginificant decreased in RIP3-/- mice. Thus, RIP3-/- mice exhibited an impaired tissue repair in response to DSS. In a conclusion, RIP3 deficiency exerted detrimental effects in DSS induced colitis partially because of the impaired repair-associated cytokines expression.
Assuntos
Colite Ulcerativa/complicações , Citocinas/metabolismo , Sulfato de Dextrana/toxicidade , Modelos Animais de Doenças , Inflamação/etiologia , Proteína Serina-Treonina Quinases de Interação com Receptores/fisiologia , Animais , Colite Ulcerativa/induzido quimicamente , Colite Ulcerativa/metabolismo , Colite Ulcerativa/patologia , Citocinas/genética , Inflamação/metabolismo , Inflamação/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Índice de Gravidade de DoençaRESUMO
BACKGROUND/AIMS: Signal transducer and activator of transcription (STAT) pathway plays an important role in antiviral efficacy of interferon alpha (IFN-α). IFN-α is the main therapeutic against hepatitis C virus (HCV) infection. We explored effects of IFN-α on HCV replication and antiviral gene expression by targeting STAT. METHODS: In response to IFN-α, STAT status, HCV replication, and antiviral gene expression were analyzed in human hepatoma Huh7.5.1 cells before and after cell culture-derived HCV infection. RESULTS: IFN-α treatment induced expression and phosphorylation of STAT1 and STAT2 in Huh7.5.1 cells. Pretreatment of Huh7.5.1 cells with a mAb to IFN alpha receptor (IFNAR) 2 decreased IFN-α-dependent phosphorylation of STAT1 and STAT2, whereas pretreatment with an IFNAR1 mAb increased such phosphorylation, suggesting that IFNAR mediates IFN-α-triggered STAT signaling. During HCV infection, STAT1 and STAT2 phosphorylation could be rescued by IFN-α and IFN-α-induced phosphorylation of STAT1 and STAT2 was impaired. Inhibition of STAT pathway by Jak inhibitor I significantly enhanced HCV RNA replication and viral protein expression. Antiviral genes coding for IFN regulatory factor 9 and IFN-stimulated gene 15 were up-regulated by IFN-α during HCV infection but such up-regulation was abrogated by Jak inhibitor I. CONCLUSION: These results establish that activation of STAT pathway is essential for anti-HCV efficacy of IFN-α. Impairment of IFN-α-triggered STAT signaling by HCV may account for evading IFN-α response.
Assuntos
Hepacivirus/efeitos dos fármacos , Interferon-alfa/farmacologia , Fator de Transcrição STAT1/metabolismo , Fator de Transcrição STAT2/metabolismo , Transdução de Sinais/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Hepatite C/metabolismo , Hepatite C/patologia , Humanos , Janus Quinases/antagonistas & inibidores , Janus Quinases/metabolismo , Cinética , Fosforilação/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Receptores de Interferon/metabolismoRESUMO
Despite recent progress in the development of hepatitis C virus (HCV) inhibitors, cost-effective antiviral drugs, especially among the patients receiving liver transplantations, are still awaited. Schisandra is a traditional medicinal herb used to treat a range of liver disorders including hepatitis for thousands of years in China. To isolate the bioactive compounds of schisandra for the treatment of HCV infection, we screened a schisandra-extracts library and identified a tetracyclic triterpenoid, schizandronic acid (SZA), as a novel HCV entry inhibitor. Our findings suggested that SZA potently inhibited pan-HCV genotype entry into hepatoma cells and primary human hepatocytes without interfering virus binding on cell surface or internalization. However, virion-cell fusion process was impaired in the presence of SZA, along with the increased host membrane fluidity. We also found that SZA inhibited the spread of HCV to the neighboring cells, and combinations of SZA with interferon or telaprevir resulted in additive synergistic effect against HCV. Additionally, SZA diminished the establishment of HCV infection in vivo. The SZA target is different from conventional direct-acting antiviral agents, therefore, SZA is a potential therapeutic compound for the development of effective HCV entry inhibitors, especially for patients who need to prevent HCV reinfection during the course of liver transplantations.
Assuntos
Antivirais/administração & dosagem , Hepacivirus/efeitos dos fármacos , Hepatite C/virologia , Schisandra/química , Triterpenos/administração & dosagem , Animais , Antivirais/química , Antivirais/farmacologia , Linhagem Celular , Modelos Animais de Doenças , Sinergismo Farmacológico , Medicamentos de Ervas Chinesas/administração & dosagem , Medicamentos de Ervas Chinesas/farmacologia , Genótipo , Células HEK293 , Hepacivirus/genética , Hepatócitos , Humanos , Interferons/administração & dosagem , Interferons/farmacologia , Camundongos , Oligopeptídeos/administração & dosagem , Oligopeptídeos/farmacologia , Triterpenos/química , Triterpenos/farmacologia , Ligação Viral , Internalização do Vírus/efeitos dos fármacos , Replicação ViralRESUMO
We aimed to investigate regulation of signal transducer and activator of transcription 3 (STAT3) and suppressor of cytokine signaling 3 (SOCS3) by interferon alpha (IFN-α) and to analyze the relationship between STAT3 and SOCS3 during hepatitis C virus (HCV) infection. Changes in STAT3 and SOCS3 were analyzed at both mRNA and protein levels in human hepatoma cells infected with HCV (J6/JFH1). At 72h of HCV infection, STAT3 expression was decreased with sustained phosphorylation, and IFN-α increased such decrease and phosphorylation. HCV increased SOCS3 expression, while IFN-α impaired such increase, indicating different regulation of STAT3 and SOCS3 by IFN-α. IFN-α-induced expression and phosphorylation of upstream kinases of the JAK/STAT pathway, Tyk2 and Jak1, were suppressed by HCV. Moreover, knockdown of STAT3 by RNA interference led to decreases in HCV RNA replication and viral protein expression, without affecting either the expression of Tyk2 and Jak1 or the SOCS3 induction in response to IFN-α. These results show that IFN-α antagonizes STAT3 and SOCS3 signaling triggered by HCV and that STAT3 regulation correlates inversely with SOCS3 induction by IFN-α, which may be important in better understanding the complex interplay between IFN-α and signal molecules during HCV infection.
Assuntos
Hepacivirus/fisiologia , Interferon-alfa/fisiologia , Fator de Transcrição STAT3/antagonistas & inibidores , Transdução de Sinais , Proteínas Supressoras da Sinalização de Citocina/antagonistas & inibidores , Carcinoma Hepatocelular , Linhagem Celular Tumoral , Regulação da Expressão Gênica , Humanos , Interferon alfa-2 , Interferon-alfa/farmacologia , Neoplasias Hepáticas , Proteínas Recombinantes/farmacologia , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Proteínas Supressoras da Sinalização de Citocina/genética , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Replicação ViralRESUMO
Although much progress has been made in antiviral agents against hepatitis C virus (HCV) in recent years, novel HCV inhibitors with improved efficacy, optimized treatment duration and more affordable prices are still urgently needed. Here, we report the identification of a natural plant-derived lignan, trachelogenin (TGN), as a potent entry inhibitor of HCV without genotype specificity, and with low cytotoxicity. TGN was extracted and purified from Caulis trachelospermi, a traditional Chinese herb with anti-inflammatory and analgesic effects. A crucial function of TGN was the inhibition of HCV entry during a post-binding step without affecting virus replication, translation, assembly and release. TGN blocked virus infection by interfering with the normal interactions between HCV glycoprotein E2 and the host entry factor CD81, which are key processes for valid virus entry. In addition, TGN diminished HCV cell-to-cell spread and exhibited additional synergistic effects when combined with IFN or telaprevir. In conclusion, this study highlights the effect of a novel HCV entry inhibitor, TGN, which has a target that differs from those of the current antiviral agents. Therefore, TGN is a potential candidate for future cocktail therapies to treat HCV-infected patients.
Assuntos
4-Butirolactona/análogos & derivados , Hepacivirus/fisiologia , Tetraspanina 28/metabolismo , Internalização do Vírus/efeitos dos fármacos , 4-Butirolactona/farmacologia , Relação Dose-Resposta a Droga , Genótipo , Hepacivirus/genética , Hepatócitos/virologia , Humanos , Estrutura Molecular , Tetraspanina 28/genética , Montagem de Vírus/efeitos dos fármacos , Liberação de Vírus , Replicação Viral/efeitos dos fármacos , Replicação Viral/fisiologiaRESUMO
Hepatitis C virus (HCV) infection affects approximately 3% of the world's population and causes chronic liver diseases, including liver fibrosis, cirrhosis, and hepatocellular carcinoma. Although current antiviral therapy comprising direct-acting antivirals (DAAs) can achieve a quite satisfying sustained virological response (SVR) rate, it is still limited by viral resistance, long treatment duration, combined adverse reactions, and high costs. Moreover, the currently marketed antivirals fail to prevent graft reinfections in HCV patients who receive liver transplantations, probably due to the cell-to-cell transmission of the virus, which is also one of the main reasons behind treatment failure. HCV entry is a highly orchestrated process involving initial attachment and binding, post-binding interactions with host cell factors, internalization, and fusion between the virion and the host cell membrane. Together, these processes provide multiple novel and promising targets for antiviral therapy. Most entry inhibitors target host cell components with high genetic barriers and eliminate viral infection from the very beginning of the viral life cycle. In future, the addition of entry inhibitors to a combination of treatment regimens might optimize and widen the prevention and treatment of HCV infection. This review summarizes the molecular mechanisms and prospects of the current preclinical and clinical development of antiviral agents targeting HCV entry.
Assuntos
Antivirais/farmacologia , Hepatite C Crônica/tratamento farmacológico , Hepatite C/tratamento farmacológico , Hepatócitos/virologia , Internalização do Vírus/efeitos dos fármacos , Antivirais/química , Antivirais/uso terapêutico , Descoberta de Drogas , Quimioterapia Combinada , Hepacivirus/efeitos dos fármacos , Hepacivirus/fisiologia , Humanos , Interferon-alfa/uso terapêutico , Neoplasias Hepáticas/tratamento farmacológico , Transplante de FígadoRESUMO
Our previous study reported that retinoic acid induced 16 (RAI16) could enhance tumorigenesis in hepatocellular carcinoma (HCC). However, the cellular functions of RAI16 are still unclear. In this study, by immunoprecipitation and tandem (MS/MS) mass spectrometry analysis, we identified that RAI16 interacted with the type II regulatory subunit of PKA (PKA-RIIα), acting as a novel protein kinase A anchoring protein (AKAP). In addition, RAI16 also interacted with heat shock protein 70 (HSP70) and 14-3-3θ. Further studies indicated that RAI16 mediated PKA phosphorylation of HSP70 at serine 486, resulting in anti-apoptosis events. RAI16 was also phosphorylated by the anchored PKA at serine 325, which promoted the recruitment of 14-3-3θ, which, in turn, inhibited RAI16 mediated PKA phosphorylation of HSP70. These findings offer mechanism insight into RAI16 mediated anti-apoptosis signaling in HCC.
Assuntos
Proteínas 14-3-3/metabolismo , Proteínas de Ancoragem à Quinase A/metabolismo , Subunidade RIIalfa da Proteína Quinase Dependente de AMP Cíclico/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas/metabolismo , Apoptose/fisiologia , Carcinoma Hepatocelular/patologia , Linhagem Celular , Sobrevivência Celular , Transformação Celular Neoplásica , Células HEK293 , Humanos , Neoplasias Hepáticas/patologia , Fosforilação , Transdução de Sinais , Espectrometria de Massas em TandemRESUMO
Hepatitis C virus (HCV) entry is a sequential and multi-step process that includes receptor interactions followed by pH-dependent membrane fusion. Specific and conserved histidine residues on the viral envelope proteins are involved in most pH-induced virus entries. In the case of HCV, some conserved histidines on the E1 and E2 proteins have been investigated in HCV pseudotype particle (HCVpp) systems. However, the roles of these histidines in cell-culture-derived HCV particle (HCVcc) systems remain unclear due to the different aspects of the viral life cycle emphasized by the two systems. In this study, the role of two conserved histidines (His490 and His621, located in domains II and III of E2, respectively) in HCV infection was evaluated in the context of JFH-1-based HCVcc using alanine substitutions. The infectivity of the H490A mutant decreased in spite of comparable initial RNA replication, protein expression and assembly efficiency as WT virus. The H621A mutant did not affect viral protein expression, but exhibited no obvious infectivity; there were fewer core proteins in the culture supernatant compared with WT virus, indicating the partially deficient virus assembly. The HCV receptor CD81-binding ability of the two mutant E2s was assessed further using enzyme immunoassays. The CD81-binding activity of H490A-E2 was reduced, and H621A-E2 was unable to bind to CD81. These data revealed the crucial role played by His490 and His621 in HCV infection, particularly during CD81 binding in cell entry. These results also contributed to the mechanical identification of the histidines involved in pH-dependent HCV entry.
Assuntos
Hepacivirus/fisiologia , Histidina/genética , Histidina/metabolismo , Tetraspanina 28/metabolismo , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/metabolismo , Internalização do Vírus , Alanina/genética , Alanina/metabolismo , Substituição de Aminoácidos , Análise Mutacional de DNA , Hepacivirus/genética , Interações Hospedeiro-Patógeno , Humanos , Ligação Proteica , RNA Viral/genéticaRESUMO
BACKGROUND: Hepatitis C virus (HCV) infection was recently recognized as an independent risk factor for insulin resistance (IR), the onset phase of type 2 diabetes mellitus (T2DM). Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) negatively regulates PI3K/Akt signaling pathway, which is critical for IR development and progression of cirrhosis to hepatocellular carcinoma (HCC). Here, we investigate the role of PTEN in HCV-associated IR and explored the mechanisms by which HCV regulates PTEN. METHODS: Western blotting was used to detect the levels of insulin signaling pathway components, including insulin receptor substrate-1 (IRS-1), phosphorylated IRS-1 (pIRS-1) at serine 307 (Ser307), both phosphorylated Akt (pAkt) and total Akt. A time-course experiment measuring activation of the insulin signaling pathway was performed to assess the effect of HCV infection on insulin sensitivity by examining the phosphorylation levels of Akt and GSK3ß, a downstream target of Akt. Huh7.5.1 cells were transduced with a lentiviral vector expressing PTEN or PTEN shRNA, and IRS-1 and pIRS-1 (Ser307) levels were determined in both HCV-infected and uninfected cells. The pc-JFH1-core plasmid was constructed to explore the underlying mechanisms by which HCV regulated PTEN and therefore IRS-1 levels. RESULTS: HCV infection inhibited the insulin signaling pathway by reducing the levels of IRS-1 and pAkt/Akt while increasing phosphorylation of IRS-1 Ser307. In addition, HCV infection decreased the sensitivity to insulin-induced stimulation by inhibiting Akt and GSK3ß phosphorylation. Furthermore, PTEN mRNA and protein levels were reduced upon HCV infection as well as transfection with the pc-JFH1-core plasmid. The reduction in IRS-1 level observed in HCV-infected cells was rescued to a limited extent by overexpression of PTEN, which in turn slightly reduced pIRS-1 (Ser307) level. In contrast, IRS-1 level were significantly decreased and phosphorylation of IRS-1 at Ser-307 was strongly enhanced by PTEN knockdown, suggesting that both reduction in IRS-1 level and increase in IRS-1 phosphorylation at Ser307 upon HCV infection occurred in a PTEN-dependent manner. CONCLUSIONS: HCV infection suppresses the insulin signaling pathway and promotes IR by repressing PTEN, subsequently leading to decreased levels of IRS-1 and increased levels of pIRS-1 at Ser307. The findings provide new insight on the mechanism of HCV-associated IR.