Nuclear localization of nucleocapsid-like particles and HCV core protein in hepatocytes of a chronically HCV-infected patient

Falcón, Viviana; Acosta‐Rivero, Nelson; Chinea, Glay; Rosa, Maria Cristina; Menéndez, Ivón; Dueñas‐Carrera, Santiago; Gra, Bienvenido; Rodríguez, Armando; Tsutsumi, Vı́ctor; Shibayama, Mineko; Luna-Muñoz, José; Miranda-Sanchez, Maria M; Morales-Grillo, Juan; Kourí, Juan B.

doi:10.1016/j.bbrc.2003.08.118

Cited by 27 publications

(20 citation statements)

References 29 publications

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“…Although the capacity of culture-produced HCV from a different genotype (2a) to infect PBMC has been challenged [52], it has also been shown that HCV from the same genotype as the one used in this manuscript (1a) [51] infects primary CD4+ T cells. HCV-Core could also enter CD4+ T cells as it has previously been suggested [23], [40], [53] and data showing that HCV-core protein is present in hepatocytes[54], non-parenchymal liver cells including lymphocytes [55] and in the serum of infected patients [56], together with data showing that it can enter hepatoma cell lines [57] further reinforces such an hypothesis. The presence of naked HCV-core particles has also been associated with active disease while lipid-associated HCV-core particles have been associated with clinical remission of liver damage [58].…”

Section: Introductionsupporting

confidence: 66%

CD4+ Primary T Cells Expressing HCV-Core Protein Upregulate Foxp3 and IL-10, Suppressing CD4 and CD8 T Cells

et al. 2014

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Adaptive T cell responses are critical for controlling HCV infection. While there is clinical evidence of a relevant role for regulatory T cells in chronic HCV-infected patients, based on their increased number and function; mechanisms underlying such a phenomena are still poorly understood. Accumulating evidence suggests that proteins from Hepatitis C virus can suppress host immune responses. We and others have shown that HCV is present in CD4+ lymphocytes from chronically infected patients and that HCV-core protein induces a state of unresponsiveness in the CD4+ tumor cell line Jurkat. Here we show that CD4+ primary T cells lentivirally transduced with HCV-core, not only acquire an anergic phenotype but also inhibit IL-2 production and proliferation of bystander CD4+ or CD8+ T cells in response to anti-CD3 plus anti-CD28 stimulation. Core-transduced CD4+ T cells show a phenotype characterized by an increased basal secretion of the regulatory cytokine IL-10, a decreased IFN-γ production upon stimulation, as well as expression of regulatory T cell markers, CTLA-4, and Foxp3. A significant induction of CD4+CD25+CD127lowPD-1highTIM-3high regulatory T cells with an exhausted phenotype was also observed. Moreover, CCR7 expression decreased in HCV-core expressing CD4+ T cells explaining their sequestration in inflamed tissues such as the infected liver. This work provides a new perspective on de novo generation of regulatory CD4+ T cells in the periphery, induced by the expression of a single viral protein.

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Section: Introductionsupporting

confidence: 66%

CD4+ Primary T Cells Expressing HCV-Core Protein Upregulate Foxp3 and IL-10, Suppressing CD4 and CD8 T Cells

et al. 2014

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“…Among the different populations displaying heterogeneous buoyant densities, the high-density particles are composed of naked viral cores and/ or immune complexes [6,7]. Naked capsids have also been reported in liver cells of infected patients [8].…”

Section: Introductionmentioning

confidence: 99%

Evidence for cellular uptake of recombinant hepatitis C virus non‐enveloped capsid‐like particles

et al. 2007

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Although the hepatitis C virus (HCV) is an enveloped virus, naked nucleocapsids have been reported in the serum of infected patients, and most recently novel HCV subgenomes with deletions of the envelope proteins have been identified. However the significance of these findings remains unclear. In this study, we used the baculovirus expression system to generate recombinant HCV capsid-like particles, and investigated their possible interactions with cells. We show that expression of HCV core in insect cells can sufficiently direct the formation of capsid-like particles in the absence of the HCV envelope glycoproteins and of the 5 0 untranslated region. By confocal microscopy analysis, we provide evidence that the naked capsid-like particles could be uptaken by human hepatoma cells. Moreover, our findings suggest that they have the potential to produce cell-signaling effects.

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“…Accordingly, the core protein is mainly detected in the cytoplasm of hepatocytes in acute HBV infection of the liver. Independent of this main pathway, the question remains as to whether HBc subunits possess a specific intranuclear function similar to those suggested for several RNA viruses, such as hepatitis C, dengue and influenza viruses (Bui et al, 2002;Falcon et al, 2003; Wang et al, 2002 (Bock et al, 1994). Furthermore, the core protein of duck hepatitis B virus (DHBc) was found in specific intranuclear bodies, co-localizing with splicing-factor compartments, shortly after infection of primary duck hepatocytes (Mabit et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Accordingly, the core protein is mainly detected in the cytoplasm of hepatocytes in acute HBV infection of the liver. Independent of this main pathway, the question remains as to whether HBc subunits possess a specific intranuclear function similar to those suggested for several RNA viruses, such as hepatitis C, dengue and influenza viruses (Bui et al, 2002;Falcon et al, 2003;Wang et al, 2002). In support of such a nuclear function, it has been demonstrated that HBV core antibodies precipitate nucleosomes and nucleoproteins in HBc-transfected HepG2 cells.…”

Section: Introductionmentioning

confidence: 99%

Assembly and export determine the intracellular distribution of hepatitis B virus core protein subunits

Weigand

Knaust

Schaller

2009

Journal of General Virology

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Little is known about the parameters and factors that determine the intracellular distribution of the hepatitis B virus core protein (HBc). In order to study HBc in living cells, HBc was tagged with green fluorescent protein (GFP). Being assembly-incompetent, the GFP-fusion protein was distributed equally throughout the cell. Mutational inactivation of known serine-phosphorylation sites within the C-terminal region led to predominantly intranuclear localization. Phosphorylation of these targets, presumably by an SR domain protein kinase, resulted in a predominantly cytoplasmic localization, which suggests active cytoplasmic export or retention. The phosphoserine itself, and not its negative charge, appears essential for the underlying mechanism. In addition, the arginine-rich, protamine-like domain surrounding these phosphorylation sites does not function as the dominant nuclear-localization signal, as had been assumed previously, because neither deleting nor altering these sequences led to a change in intracellular HBc subunit distribution. Restoring the capability of the fusion protein to form capsids by co-assembly with assembly-competent, sterically uncompromised HBc subunits provided a second assay that gave insight into the effects resulting from capsid formation. Assembly was found to be the dominant factor in the cytoplasmic retention of the GFP-HBc fusion protein. Furthermore, the stability of these empty capsids was influenced by the cell-cycle inhibitor nocodazole. Thus, the intracellular distribution of HBc is dominated by cytoplasmic assembly, which is supported by the active nuclear export of HBc subunits, and modulated during the cell cycle by the instability of capsids. INTRODUCTIONHepatitis B virus (HBV) is an enveloped virus with a 3.2 kb genome containing four genes, which encode proteins with multiple functions. This is also exemplified by the 183 aa HBV core protein (HBc). It assembles into the nucleocapsid, interacting with the pregenomic RNA and the viral polymerase. In addition, HBc is involved in the process of reverse transcription and also in the second-strand synthesis of the DNA genome. It targets mature nucleocapsids to the endoplasmic reticulum, where it is believed to interact specifically with the envelope protein (Ganem, 1991;Seeger & Mason, 2000;Seifer & Standring, 1995;Wynne et al., 1999). X-ray analyses and cryo-electron microscopy, as well as mutational analyses, have revealed that HBc is a two-domain protein: a globular assembly domain encompassing aa 10-140, and an unstructured regulatory sequence containing a protamine-like domain (Seifer & Standring, 1995;Wynne et al., 1999), which is essential for the encapsidation of the pregenomic RNA and reverse transcription (Köck et al., 2004;Nassal, 1992) and supposedly for nuclear import (see below).Newly synthesized HBc remains in the cytoplasm of the infected cell, where it assembles into capsids as a first step in the formation of progeny virions. Accordingly, the core protein is mainly detected in the cytoplasm of hepatocytes...

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Nuclear localization of nucleocapsid-like particles and HCV core protein in hepatocytes of a chronically HCV-infected patient

Cited by 27 publications

References 29 publications

CD4+ Primary T Cells Expressing HCV-Core Protein Upregulate Foxp3 and IL-10, Suppressing CD4 and CD8 T Cells

CD4+ Primary T Cells Expressing HCV-Core Protein Upregulate Foxp3 and IL-10, Suppressing CD4 and CD8 T Cells

Evidence for cellular uptake of recombinant hepatitis C virus non‐enveloped capsid‐like particles

Assembly and export determine the intracellular distribution of hepatitis B virus core protein subunits

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