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Interferon-α inducible protein 6 impairs EGFR activation by CD81 and inhibits hepatitis C virus infection.

Meyer K, Kwon YC, Liu S, Hagedorn CH, Ray RB, Ray R - Sci Rep (2015)

Bottom Line: HCV RNA level or infectious foci were inhibited significantly by ectopic expression of IFI6.Taken together, the results from our study support a model where IFI6 inhibits HCV entry by impairing EGFR mediated CD81/CLDN1 interactions.This may be relevant to other virus entry processes employing EGFR.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Saint Louis University.

ABSTRACT
Viral entry requires co-operative interactions of several host cell factors. Interferon (IFN) and the IFN-stimulated genes (ISGs) play a central role in antiviral responses against hepatitis C virus (HCV) infection. We examined the effect of interferon-α inducible protein 6 (IFI6) against HCV infection in human hepatoma cells. HCV RNA level or infectious foci were inhibited significantly by ectopic expression of IFI6. IFI6 impaired CD81 co-localization with claudin-1 (CLDN1) upon HCV infection or CD81 cross-linking by specific antibody. Activation of epidermal growth factor receptor (EGFR), a co-factor involved in CD81/CLDN1 interactions, was reduced in IFI6 expressing cells in response to HCV infection or CD81 cross linking by antibody, but not by treatment with EGF. Taken together, the results from our study support a model where IFI6 inhibits HCV entry by impairing EGFR mediated CD81/CLDN1 interactions. This may be relevant to other virus entry processes employing EGFR.

No MeSH data available.


Related in: MedlinePlus

IFI6 expression inhibits CD81 and CLDN1 interactions during antibody cross-linked activation of CD81.Expression of CD81 and CLDN1 on the cell surface of unstimulated control and Huh7.5 stable transfectants expressing IFI6 is shown (panels A and E; respectively). CD81 (panel B) and CLDN1 (panel C) were detected in fixed mock-transfected control Huh7.5 cells. Merged fluorescence showing translocation of CD81 and co-localization with CLDN1 in tight junctions of cells (panel D, 56% co-localization of claudin with CD81 per field). CD81 (panel F), CLDN1 (panel G), and merged immunofluorescence analysis displaying localization (panel H, <0.1% co-localization of claudin with CD81 per field) are shown in IFI6 transfected cells. Each panel is representative of three independent experiments.
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f3: IFI6 expression inhibits CD81 and CLDN1 interactions during antibody cross-linked activation of CD81.Expression of CD81 and CLDN1 on the cell surface of unstimulated control and Huh7.5 stable transfectants expressing IFI6 is shown (panels A and E; respectively). CD81 (panel B) and CLDN1 (panel C) were detected in fixed mock-transfected control Huh7.5 cells. Merged fluorescence showing translocation of CD81 and co-localization with CLDN1 in tight junctions of cells (panel D, 56% co-localization of claudin with CD81 per field). CD81 (panel F), CLDN1 (panel G), and merged immunofluorescence analysis displaying localization (panel H, <0.1% co-localization of claudin with CD81 per field) are shown in IFI6 transfected cells. Each panel is representative of three independent experiments.

Mentions: The possibility that HCV entry dependent on co-receptor complex formation between the tetraspanin superfamily member CD81 and the tight junction protein claudin1 (CLDN1) on cell membranes was tested. Control and IFI6 expressing Huh7.5 cells were incubated with CD81 specific JS-81 antibody for 60 minutes at 37°C, followed by fixation and permeabilization1130. Co-localization of CD81 and CLDN1 proteins was observed in control cells (8.9% co-localization of CD81 with CLDN1 per field, 56% co-localization in selected stimulated cells) (Fig. 3, panels B-D), while limited co-localization of CD81 and CLDN1 was observed in cells expressing IFI6 protein as measured by immunofluorescence (<0.1% co-localization of CD81 with CLDN1 per field) (Fig. 3, panels F-H). Unless indicated, co-localization was measured in triplicate using confocal images taken at 20x of no fewer than 100 cells. These results suggested that HCV entry might be impaired due to a lack of CLDN1 and CD81 co-receptor interaction in cells expressing IFI6.


Interferon-α inducible protein 6 impairs EGFR activation by CD81 and inhibits hepatitis C virus infection.

Meyer K, Kwon YC, Liu S, Hagedorn CH, Ray RB, Ray R - Sci Rep (2015)

IFI6 expression inhibits CD81 and CLDN1 interactions during antibody cross-linked activation of CD81.Expression of CD81 and CLDN1 on the cell surface of unstimulated control and Huh7.5 stable transfectants expressing IFI6 is shown (panels A and E; respectively). CD81 (panel B) and CLDN1 (panel C) were detected in fixed mock-transfected control Huh7.5 cells. Merged fluorescence showing translocation of CD81 and co-localization with CLDN1 in tight junctions of cells (panel D, 56% co-localization of claudin with CD81 per field). CD81 (panel F), CLDN1 (panel G), and merged immunofluorescence analysis displaying localization (panel H, <0.1% co-localization of claudin with CD81 per field) are shown in IFI6 transfected cells. Each panel is representative of three independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4355636&req=5

f3: IFI6 expression inhibits CD81 and CLDN1 interactions during antibody cross-linked activation of CD81.Expression of CD81 and CLDN1 on the cell surface of unstimulated control and Huh7.5 stable transfectants expressing IFI6 is shown (panels A and E; respectively). CD81 (panel B) and CLDN1 (panel C) were detected in fixed mock-transfected control Huh7.5 cells. Merged fluorescence showing translocation of CD81 and co-localization with CLDN1 in tight junctions of cells (panel D, 56% co-localization of claudin with CD81 per field). CD81 (panel F), CLDN1 (panel G), and merged immunofluorescence analysis displaying localization (panel H, <0.1% co-localization of claudin with CD81 per field) are shown in IFI6 transfected cells. Each panel is representative of three independent experiments.
Mentions: The possibility that HCV entry dependent on co-receptor complex formation between the tetraspanin superfamily member CD81 and the tight junction protein claudin1 (CLDN1) on cell membranes was tested. Control and IFI6 expressing Huh7.5 cells were incubated with CD81 specific JS-81 antibody for 60 minutes at 37°C, followed by fixation and permeabilization1130. Co-localization of CD81 and CLDN1 proteins was observed in control cells (8.9% co-localization of CD81 with CLDN1 per field, 56% co-localization in selected stimulated cells) (Fig. 3, panels B-D), while limited co-localization of CD81 and CLDN1 was observed in cells expressing IFI6 protein as measured by immunofluorescence (<0.1% co-localization of CD81 with CLDN1 per field) (Fig. 3, panels F-H). Unless indicated, co-localization was measured in triplicate using confocal images taken at 20x of no fewer than 100 cells. These results suggested that HCV entry might be impaired due to a lack of CLDN1 and CD81 co-receptor interaction in cells expressing IFI6.

Bottom Line: HCV RNA level or infectious foci were inhibited significantly by ectopic expression of IFI6.Taken together, the results from our study support a model where IFI6 inhibits HCV entry by impairing EGFR mediated CD81/CLDN1 interactions.This may be relevant to other virus entry processes employing EGFR.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Saint Louis University.

ABSTRACT
Viral entry requires co-operative interactions of several host cell factors. Interferon (IFN) and the IFN-stimulated genes (ISGs) play a central role in antiviral responses against hepatitis C virus (HCV) infection. We examined the effect of interferon-α inducible protein 6 (IFI6) against HCV infection in human hepatoma cells. HCV RNA level or infectious foci were inhibited significantly by ectopic expression of IFI6. IFI6 impaired CD81 co-localization with claudin-1 (CLDN1) upon HCV infection or CD81 cross-linking by specific antibody. Activation of epidermal growth factor receptor (EGFR), a co-factor involved in CD81/CLDN1 interactions, was reduced in IFI6 expressing cells in response to HCV infection or CD81 cross linking by antibody, but not by treatment with EGF. Taken together, the results from our study support a model where IFI6 inhibits HCV entry by impairing EGFR mediated CD81/CLDN1 interactions. This may be relevant to other virus entry processes employing EGFR.

No MeSH data available.


Related in: MedlinePlus