Article

Contrasting Roles of Mitogen-activated Protein Kinases in Cellular Entry and Replication of Hepatitis C Virus: MKNK1 Facilitates Cell Entry.

Division of Infectious Diseases, Department of Medicine, and the Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7292.
Journal of Virology (Impact Factor: 4.65). 01/2013; 87(8). DOI: 10.1128/JVI.00954-12
Source: PubMed

ABSTRACT The human kinome comprises over 800 individual kinases. These contribute in multiple ways to regulation of cellular metabolism and may have direct and indirect effects on virus replication. Kinases are tempting therapeutic targets for drug development, but achieving sufficient specificity is often a challenge for chemical inhibitors. While using inhibitors to assess whether c-Jun N-terminal (JNK) kinases regulate hepatitis C virus (HCV) replication, we encountered unexpected off-target effects that led us to discover a role for a mitogen activated protein kinase (MAPK)-related kinase, MAP kinase interacting serine/threonine kinase 1 (MKNK1), in viral entry. Two JNK inhibitors, AS601245 and SP600125, and RNAi-mediated knockdown of JNK1 and JNK2, enhanced replication of HCV replicon RNAs as well as infectious genome-length RNA transfected into Huh-7 cells. JNK knockdown also enhanced replication following infection with cell-free virus, suggesting that JNK actively restricts HCV replication. Despite this, AS601245 and SP600125 both inhibited viral entry. Screening of a panel of inhibitors targeting kinases that are potentially modulated by off-target effects of AS601245 and SP600125 led us to identify MKNK1 as a host factor involved in HCV entry. Chemical inhibition or siRNA knockdown of MKNK1 significantly impaired entry of genotype 1a HCV and HCV-pseudotyped lentiviral particles (HCVpp) in Huh-7 cells, but had only minimal impact on viral RNA replication, or cell proliferation and viability. We propose a model by which MKNK1 acts to facilitate viral entry downstream of the epidermal growth factor receptor (EGFR) and extracellular signal-regulated kinase (ERK), both of which have been implicated in the entry process.

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    • "PKA Protein kinase A Entry, receptor complex formation [27] PLK1 Polo-like kinase 1 Replication, assembly [42] SNARK SNF1/AMP kinase-related kinase Lipogenesis, assembly [47] 2 C.C. Colpitts et al. / Biochimica et Biophysica Acta xxx (2015) xxx–xxx the c-Jun N-terminal kinase family, the mitogen-activated protein kinase (MAPK) interacting serine/threonine kinase 1 (MKNK1), which was recently identified as another HCV co-entry factor [26]. These signaling pathways induce actin remodeling, thereby facilitating the lateral movement of CD81–HCV complexes along the cell surface toward the tight junction. "
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    ABSTRACT: Hepatitis C virus (HCV) infection relies on virus-host interactions with human hepatocytes, a context in which host cell kinases play critical roles in every step of the HCV life cycle. During viral entry, cellular kinases, including EGFR, EphA2 and PKA, regulate the localization of host HCV entry factors and induce receptor complex assembly. Following virion internalization, viral genomes replicate on endoplasmic reticulum-derived membranous webs. The formation of membranous webs depends on interactions between the HCV NS5a protein and PI4KIIIα. The phosphorylation status of NS5a, regulated by PI4KIIIα, CKI and other kinases, also acts as a molecular switch to virion assembly, which takes place on lipid droplets. The formation of lipid droplets is enhanced by HCV activation of IKKα. In view of the multiple crucial steps in the viral life cycle that are mediated by host cell kinases, these enzymes also represent complementary targets for antiviral therapy. This article is part of a Special Issue entitled:Inhibitors of Protein Kinases. Copyright © 2015. Published by Elsevier B.V.
    Biochimica et Biophysica Acta 04/2015; DOI:10.1016/j.bbapap.2015.04.011 · 4.66 Impact Factor
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    • "This interaction seems to be promoted by epidermal growth factor receptor (EGFR) and also potentially by protein kinase A [67] [68]. Following EGFR stimulation, the Ras/MEK/ERK pathway is activated, which could lead to the activation of MAPK interacting serine/threonine kinase 1 (MKNK1), a kinase which facilitates HCV entry downstream of EGFR activation [69]. Furthermore , activation of EGFR also stimulates HRas, which in turn associates with CD81, and this interaction is required for CD81 lateral diffusion, allowing CD81-CLDN1 to associate [70]. "
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    ABSTRACT: Hepatitis C virus (HCV) is an important human pathogen that causes hepatitis, liver cirrhosis and hepatocellular carcinoma. It imposes a serious problem to public health in the world as the population of chronically infected HCV patients who are at risk of progressive liver disease is projected to increase significantly in the next decades. However, the arrival of new antiviral molecules is progressively changing the landscape of hepatitis C treatment. The search for new anti-HCV therapies has also been a driving force to better understand how HCV interacts with its host, and major progresses have been made on the various steps of the HCV life cycle. Here, we review the most recent advances in the fast growing knowledge on HCV life cycle and interaction with host factors and pathways.
    Journal of Hepatology 11/2014; 61(1). DOI:10.1016/j.jhep.2014.06.031 · 10.40 Impact Factor
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    • "To assess the relevance of the activation of the JNK pathway to the protective effects of H2S, hepatocytes (LO2, QSG7701) were treated with the JNK1 inhibitor SP600125 (10 μM) [21]. The administration of SP600125 significantly reduced the increase in JNK1 phosphorylation (*P < 0.05; Figure 8(b)) and enhanced the hepatoprotective effects of H2S (*P < 0.05; Figure 6(a)). "
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    ABSTRACT: Background. Hepatic ischemia/reperfusion (I/R) injury is an important clinical problem, and its consequences can seriously threaten human health. Apoptosis and autophagy have been shown to contribute to cell death in hepatic I/R injury. Hydrogen sulfide (H2S) is the third most common endogenously produced gaseous signaling molecule and is known to exert a protective effect against hepatic I/R injury. In this study, the purpose is to explore both the effect and mechanism of H2S on hepatic I/R injury. Methods. Balb/c mice were randomized into Sham, I/R, or two doses (14 μ mol/kg and 28 μ mol/kg) of sodium hydrosulfide (NaHS, an H2S donor) preconditioning groups. Results. NaHS significantly reduced the levels of TNF- α and IL-6 at 12 h and 24 h after injection compared with ischemia/reperfusion challenge alone. The expression of Bcl-2, Bax, Beclin-1, and LC3, which play important roles in the regulation of the apoptosis and autophagy pathways, was also clearly affected by NaHS. Furthermore, NaHS affected the p-JNK1, p-ERK1, and p-p38. Conclusion. Our results indicate that H2S attenuates hepatic I/R injury, at least in part, by regulating apoptosis through inhibiting JNK1 signaling. The autophagy agonist rapamycin potentiated this hepatoprotective effect by reversing the inhibition of autophagy by H2S.
    Mediators of Inflammation 05/2014; 2014:935251. DOI:10.1155/2014/935251 · 3.24 Impact Factor
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