The Niemann-Pick C1-Like 1 cholesterol absorption receptor: a novel hepatitis C virus entry factor and potential therapeutic target

Department of Medicine, University of Illinois-Chicago, Chicago, Illinois, USA.
Nature medicine (Impact Factor: 27.36). 01/2012; 18(2):281-5. DOI: 10.1038/nm.2581
Source: PubMed


Hepatitis C virus (HCV) is a leading cause of liver disease worldwide. With ∼170 million individuals infected and current interferon-based treatment having toxic side effects and marginal efficacy, more effective antivirals are crucially needed. Although HCV protease inhibitors were just approved by the US Food and Drug Administration (FDA), optimal HCV therapy, analogous to HIV therapy, will probably require a combination of antivirals targeting multiple aspects of the viral lifecycle. Viral entry represents a potential multifaceted target for antiviral intervention; however, to date, FDA-approved inhibitors of HCV cell entry are unavailable. Here we show that the cellular Niemann-Pick C1-like 1 (NPC1L1) cholesterol uptake receptor is an HCV entry factor amendable to therapeutic intervention. Specifically, NPC1L1 expression is necessary for HCV infection, as silencing or antibody-mediated blocking of NPC1L1 impairs cell culture-derived HCV (HCVcc) infection initiation. In addition, the clinically available FDA-approved NPC1L1 antagonist ezetimibe potently blocks HCV uptake in vitro via a virion cholesterol-dependent step before virion-cell membrane fusion. Moreover, ezetimibe inhibits infection by all major HCV genotypes in vitro and in vivo delays the establishment of HCV genotype 1b infection in mice with human liver grafts. Thus, we have not only identified NPC1L1 as an HCV cell entry factor but also discovered a new antiviral target and potential therapeutic agent.

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Available from: Katherine Anne Marsh, Feb 11, 2014
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    • "We report for the first time that hepatoma proliferation increases HCVpp reporter signals, demonstrating that luciferase values are not solely defined by the HCVpp entry process. This is particularly pertinent when comparing HCV entry into different cell types with varying growth rates or when evaluating the effect of antibodies, growth factors or kinase inhibitors with known effects on cell proliferation (Lupberger et al., 2011; Marukian et al., 2008; Sainz et al., 2012a). In summary, growth-arrested hepatoma cell lines support comparable rates of HCVpp entry into primary hepatocytes, validating their use as a surrogate model system. "
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    ABSTRACT: The major cell type supporting hepatitis C virus (HCV) infection is the hepatocyte, however, most reports studying viral entry and replication utilize transformed hepatoma cell lines. We demonstrate that HCV pseudoparticles (HCVpp) infect primary hepatocytes with comparable rates to hepatoma cells, demonstrating the limited variability in donor hepatocytes to support HCV receptor-glycoprotein dependent entry. In contrast, we observed a 2-log range in viral replication between the same donor hepatocytes. We noted that cell proliferation augments pseudoparticle reporter activity and arresting hepatoma cells yields comparable levels of infection to hepatocytes. This study demonstrates comparable rates of HCVpp entry into primary hepatocytes and hepatoma cells, validating the use of transformed cells as a model system to study HCV entry.
    Preview · Article · Feb 2015 · Journal of General Virology
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    • "Finally, live cell imaging experiments indicate that HCV particles do not migrate to cell-cell contact areas after binding, supporting the idea that tight junctions might not be required for HCV entry, at least in non-polarized hepatoma cells [80]. Finally, since the HCV virion is rich in cholesterol, the role of the cholesterol transporter Niemann-Pick C1-like 1 (NPC1L1) was investigated and NPC1L1 identified as an additional entry factor [81]. Furthermore, transferrin receptor 1 has also been reported to be involved in HCV entry [82]. "
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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.
    Preview · Article · Nov 2014 · Journal of Hepatology
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    • "Other entry factors (such as occludin (OCLDN), receptor tyrosine kinases RTKs including the EGFR and EphA2 are thought to be involved at viral entry late stages [8], [9] by regulating CD81-CLDN1 coreceptor interactions and membrane fusion. Recently, NPC1L1 (a cholesterol sensing receptor expressed on apical surface of hepatocytes as well as enterocytes) [10] and transferin 1 [11] were identified as new HCV entry factor. The use of these all receptors leads to HCV internalisation by clathrin-mediated endocytosis [12], [13]. "
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    ABSTRACT: Hepatitis C virus (HCV) is a leading cause of cirrhosis and liver cancer worldwide. We recently characterized for the first time the expression of Signaling Lymphocyte Activating Molecule 3 (SLAMF3) in human hepatocytes and here, we report that SLAMF3 interacts with the HCV viral protein E2 and is implicated in HCV entry process. We found a strong correlation between SLAMF3 expression level and hepatocyte susceptibility to HCV infection. The use of specific siRNAs to down-modulate SLAMF3 expression and SLAMF3-blocking antibodies both decreased the hepatocytes susceptibility to HCV infection. Moreover, SLAMF3 over-expression significantly increased susceptibility to HCV infection. Interestingly, experiments with peptides derived from each SLAMF3 domain showed that the first N-terminal extracellular domain is essential for interaction with HCV particles. Finally, we showed that recombinant HCV envelop protein E2 can bind SLAMF3 and that anti-SLAMF3 antibodies inhibited specifically this interaction. Overall, our results revealed that SLAMF3 plays a role during HCV entry, likely by enhancing entry of viral particle within hepatocytes.
    Full-text · Article · Jun 2014 · PLoS ONE
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