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IFI6 Inhibits Apoptosis via Mitochondrial-Dependent Pathway in Dengue Virus 2 Infected Vascular Endothelial Cells.

Qi Y, Li Y, Zhang Y, Zhang L, Wang Z, Zhang X, Gui L, Huang J - PLoS ONE (2015)

Bottom Line: Interferon (IFN)-stimulated genes (ISGs) induced by dengue virus (DENV) exert antiviral effects.We observed that Bcl-2 expression was increased in IFI6+/+ and decreased in IFI6-/- cells.By contrast, Bax expression was decreased in IFI6+/+ and increased in IFI6-/- cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, PR China; Key Laboratory of Tropical Diseases Control, Ministry of Education, Guangzhou, PR China.

ABSTRACT
Dengue hemorrhagic fever (DHF)/Dengue shock syndrome (DSS) is a fatal infectious disease that demands an effective treatment. Interferon (IFN)-stimulated genes (ISGs) induced by dengue virus (DENV) exert antiviral effects. Among ISGs, IFN-α inducible gene 6 (IFI6) was increased in DENV infected human umbilical vascular endothelial cells (HUVECs) by microarray analysis in our previous study. However, its function is incompletely understood. In this study, we confirmed that IFI6 was markedly induced in DENV infection of both primary HUVECs and EA.hy926 cell lines. Recombinant EA.hy926 cell lines in which IFI6 was either over-expressed (IFI6+/+) or knocked-down (IFI6-/-) were generated. The activation of caspase-3 and intrinsic apoptosis-related protein caspase-9 were down-regulated in IFI6+/+ but up-regulated in IFI6-/- cells at 24-48 hrs post-infection. After incubation with DENV for 48 hrs, the mitochondrial membrane potential (Δψ(m)) was more stable in IFI6+/+ cells but reduced in IFI6-/- cells, as assayed by fluorescence staining with JC-1. We observed that Bcl-2 expression was increased in IFI6+/+ and decreased in IFI6-/- cells. By contrast, Bax expression was decreased in IFI6+/+ and increased in IFI6-/- cells. It is presumed that the anti-apoptotic function of IFI6 is expressed by regulating the rheostatic balance between bcl-2/bax expression and inhibition of Δψ(m) depolarization during DENV infection of vascular endothelial cells(VECs). In addition, the pro-apoptotic protein X-linked Inhibitor of Apoptosis (XIAP)-Associated Factor 1(XAF1) expression had been reported to be up-regulated and led to the induction of apoptosis in DENV2-infected VECs,but the relationship between XAF1 and IFI6 dengue virus-induced apoptosis in VECs warrants further study.

No MeSH data available.


Related in: MedlinePlus

Dengue virus infection induced IFI6 over-expression in isolated primary HUVECs and EA.hy926 cells.Expression of IFI6 was detected by GeneChip hybridization and analyzed(see Panel a, top) and mRNA expression of IFI6 was detected using qRT-PCR (see Panel a, below) at 48 hrs post-infection in HUVECs. Factor VIII antigen staining by immunocytochemistry (×400)(see Panel b, top). Analysis of CD31 expression in EA.hy926 cells by flow cytometry. The red was the negative control(see Panel b, below). (c) Protein expression of IFI6 was detected using immunoblotting in EA.hy926 cells after 24, 36, and 48 hrs post DENV2 infection. The gray scale scanning data were shown below and normalized to β-actin.
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pone.0132743.g001: Dengue virus infection induced IFI6 over-expression in isolated primary HUVECs and EA.hy926 cells.Expression of IFI6 was detected by GeneChip hybridization and analyzed(see Panel a, top) and mRNA expression of IFI6 was detected using qRT-PCR (see Panel a, below) at 48 hrs post-infection in HUVECs. Factor VIII antigen staining by immunocytochemistry (×400)(see Panel b, top). Analysis of CD31 expression in EA.hy926 cells by flow cytometry. The red was the negative control(see Panel b, below). (c) Protein expression of IFI6 was detected using immunoblotting in EA.hy926 cells after 24, 36, and 48 hrs post DENV2 infection. The gray scale scanning data were shown below and normalized to β-actin.

Mentions: IFI6 up-regulated in HUVECs after infection with DENV2 for 48 hrs by GeneChip hybridization and analysis (Fig 1, panel a, top), and mRNA expression of IFI6 in primary HUVECs isolated from human umbilical veins was markedly up-regulated after 48 hrs post DENV2 infection(Fig 1, panel a, below). EA.hy926 immunostained with the antibody against factor VIII and an HRP-conjugated secondary antibody exhibited brown DAB reaction product (Fig 1, panel b, top), while EA.hy926 cells exhibited CD31 surface staining (Fig 1, panel b, below). Immunobloting assays were employed to validate IFI6 protein levels in EA.hy926 HUVECs cells, confirming that IFI6 was increased following DENV2 infection (Fig 1c).


IFI6 Inhibits Apoptosis via Mitochondrial-Dependent Pathway in Dengue Virus 2 Infected Vascular Endothelial Cells.

Qi Y, Li Y, Zhang Y, Zhang L, Wang Z, Zhang X, Gui L, Huang J - PLoS ONE (2015)

Dengue virus infection induced IFI6 over-expression in isolated primary HUVECs and EA.hy926 cells.Expression of IFI6 was detected by GeneChip hybridization and analyzed(see Panel a, top) and mRNA expression of IFI6 was detected using qRT-PCR (see Panel a, below) at 48 hrs post-infection in HUVECs. Factor VIII antigen staining by immunocytochemistry (×400)(see Panel b, top). Analysis of CD31 expression in EA.hy926 cells by flow cytometry. The red was the negative control(see Panel b, below). (c) Protein expression of IFI6 was detected using immunoblotting in EA.hy926 cells after 24, 36, and 48 hrs post DENV2 infection. The gray scale scanning data were shown below and normalized to β-actin.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4526556&req=5

pone.0132743.g001: Dengue virus infection induced IFI6 over-expression in isolated primary HUVECs and EA.hy926 cells.Expression of IFI6 was detected by GeneChip hybridization and analyzed(see Panel a, top) and mRNA expression of IFI6 was detected using qRT-PCR (see Panel a, below) at 48 hrs post-infection in HUVECs. Factor VIII antigen staining by immunocytochemistry (×400)(see Panel b, top). Analysis of CD31 expression in EA.hy926 cells by flow cytometry. The red was the negative control(see Panel b, below). (c) Protein expression of IFI6 was detected using immunoblotting in EA.hy926 cells after 24, 36, and 48 hrs post DENV2 infection. The gray scale scanning data were shown below and normalized to β-actin.
Mentions: IFI6 up-regulated in HUVECs after infection with DENV2 for 48 hrs by GeneChip hybridization and analysis (Fig 1, panel a, top), and mRNA expression of IFI6 in primary HUVECs isolated from human umbilical veins was markedly up-regulated after 48 hrs post DENV2 infection(Fig 1, panel a, below). EA.hy926 immunostained with the antibody against factor VIII and an HRP-conjugated secondary antibody exhibited brown DAB reaction product (Fig 1, panel b, top), while EA.hy926 cells exhibited CD31 surface staining (Fig 1, panel b, below). Immunobloting assays were employed to validate IFI6 protein levels in EA.hy926 HUVECs cells, confirming that IFI6 was increased following DENV2 infection (Fig 1c).

Bottom Line: Interferon (IFN)-stimulated genes (ISGs) induced by dengue virus (DENV) exert antiviral effects.We observed that Bcl-2 expression was increased in IFI6+/+ and decreased in IFI6-/- cells.By contrast, Bax expression was decreased in IFI6+/+ and increased in IFI6-/- cells.

View Article: PubMed Central - PubMed

Affiliation: Institute of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, PR China; Key Laboratory of Tropical Diseases Control, Ministry of Education, Guangzhou, PR China.

ABSTRACT
Dengue hemorrhagic fever (DHF)/Dengue shock syndrome (DSS) is a fatal infectious disease that demands an effective treatment. Interferon (IFN)-stimulated genes (ISGs) induced by dengue virus (DENV) exert antiviral effects. Among ISGs, IFN-α inducible gene 6 (IFI6) was increased in DENV infected human umbilical vascular endothelial cells (HUVECs) by microarray analysis in our previous study. However, its function is incompletely understood. In this study, we confirmed that IFI6 was markedly induced in DENV infection of both primary HUVECs and EA.hy926 cell lines. Recombinant EA.hy926 cell lines in which IFI6 was either over-expressed (IFI6+/+) or knocked-down (IFI6-/-) were generated. The activation of caspase-3 and intrinsic apoptosis-related protein caspase-9 were down-regulated in IFI6+/+ but up-regulated in IFI6-/- cells at 24-48 hrs post-infection. After incubation with DENV for 48 hrs, the mitochondrial membrane potential (Δψ(m)) was more stable in IFI6+/+ cells but reduced in IFI6-/- cells, as assayed by fluorescence staining with JC-1. We observed that Bcl-2 expression was increased in IFI6+/+ and decreased in IFI6-/- cells. By contrast, Bax expression was decreased in IFI6+/+ and increased in IFI6-/- cells. It is presumed that the anti-apoptotic function of IFI6 is expressed by regulating the rheostatic balance between bcl-2/bax expression and inhibition of Δψ(m) depolarization during DENV infection of vascular endothelial cells(VECs). In addition, the pro-apoptotic protein X-linked Inhibitor of Apoptosis (XIAP)-Associated Factor 1(XAF1) expression had been reported to be up-regulated and led to the induction of apoptosis in DENV2-infected VECs,but the relationship between XAF1 and IFI6 dengue virus-induced apoptosis in VECs warrants further study.

No MeSH data available.


Related in: MedlinePlus