Hepatitis B virus X protein up-regulates tumor necrosis factor-αexpression in cultured mesangial cells via ERKs and NF-κB pathways

Objective: To investigate the effects of hepatitis B virus (HBV) X protein (HBx) on the expression of tumor necrosis factor-α (TNF-α) in glomerular mesangial cells (GMCs) and the underlying intracellular signal pathways. Methods: The plasmid pCI-neo-X that carries the X gene of hepatitis B virus was transfected into cultured GMCs. HBx expression in the transfected GMCs was assessed by Western-blot. TNF-α protein and mRNA were assessed by ELISA and semi-quantitative RT-PCR, respectively. Three kinase inhibitors-U0126, an inhibitor of extracellular signal-regulated kinases (ERKs);lactacystin, an inhibitor of nuclear factor-κB (NF-κB);and SB203580, a selective inhibitor of p38 MAP kinase (p38 MAPK) were used to determine which intracellular signal pathways may underlie the action of HBx on TNF-αexpression in transfected GMCs. Results:A significant increase in HBx expression in pCI-neo-X transfected GMCs was detected at 36 h and 48 h, which was not affected by any of those kinase inhibitors mentioned above. A similar increase in the expression of both TNF-αprotein and mRNA was also observed at 36 h and 48 h, which was significantly decreased in the presence of U0126 or lactacytin, but not SB203580. Conclusions:HBx upregulates TNF-αexpression in cultured GMCs, possibly through ERKs and NF-κB pathway, but not p38 MAPK pathway.

Hepatitis B virus X protein up-regulates tumor necrosis factor-α expression in cultured mesangial cells via ERKs and NF-κB pathways

<p><b>OBJECTIVE</b>To investigate the effects of hepatitis B virus (HBV) X protein (HBx) on the expression of tumor necrosis factor-α (TNF-α) in glomerular mesangial cells (GMCs) and the underlying intracellular signal pathways.</p><p><b>METHODS</b>The plasmid pCI-neo-X that carries the X gene of hepatitis B virus was transfected into cultured GMCs. HBx expression in the transfected GMCs was assessed by Western-blot. TNF-α protein and mRNA were assessed by ELISA and semi-quantitative RT-PCR, respectively. Three kinase inhibitors-U0126, an inhibitor of extracellular signal-regulated kinases (ERKs); lactacystin, an inhibitor of nuclear factor-κB (NF-κB); and SB203580, a selective inhibitor of p38 MAP kinase (p38 MAPK) were used to determine which intracellular signal pathways may underlie the action of HBx on TNF-α expression in transfected GMCs.</p><p><b>RESULTS</b>A significant increase in HBx expression in pCI-neo-X transfected GMCs was detected at 36 h and 48 h, which was not affected by any of those kinase inhibitors mentioned above. A similar increase in the expression of both TNF-α protein and mRNA was also observed at 36 h and 48 h, which was significantly decreased in the presence of U0126 or lactacytin, but not SB203580.</p><p><b>CONCLUSIONS</b>HBx upregulates TNF-α expression in cultured GMCs, possibly through ERKs and NF-κB pathway, but not p38 MAPK pathway.</p>

HBV X Gene Transfection Upregulates IL-1β and IL-6 Gene Expression and Induces Rat Glomerular Mesangial Cell Proliferation / 华中科技大学学报（医学）（英德文版）

The X gene of HBV encodes a 17-KD protein, termed HBx, which has been shown to function as a transcriptional trans-activator of a variety of viral and cellular promoter/enhancer elements. The aim of this study was to investigate the effect of HBx on gene expression of interleukin (IL)-1β and IL-6, and proliferation of rat mesangial cells in vitro. The X gene of HBV was amplified by PCR assay, and inserted into the eukaryotic expression vector pCI-neo. The structure of recombinant pCI-neo-X plasmid was proved by restrict endonuclease digestion and sequencing analysis. pCI-neo-X was transfected into cultured rat mesangial cell line in vitro via liposome. HBx expression in transfected mesangial cells was detected by Western blot. The IL-1β and IL-6 mRNA expression in those cells was assayed by semiquantitative RT-PCR. Mesangial cell proliferation was tested by MTT. The results showed that HBx was obviously expressed in cultured mesangial cell line at 36th and 48th h after transfection. The expression of IL-1β and IL-6 mRNA was simultaneously increased. The cell proliferation was also obvious at the same time. It was concluded that HBx gene transfection could induce IL-1β and IL-6 gene expression and mesangial cell proliferation. HBx may play a critical role in mesangial cell proliferation through upregulation of the IL-1β and IL-6 gene expression.