title: Hepatitis B virus X protein up-regulates tumor necrosis factor-α expression in cultured mesangial cells via ERKs and NF-κB pathways.
abstract: 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-α expression 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-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.
  
  
  CONCLUSIONS
  HBx upregulates TNF-α expression in cultured GMCs, possibly through ERKs and NF-κB pathway, but not p38 MAPK pathway.
authors.affiliation: Deptartment of Pediatrics, Clinical Medical College, Yangtze University, Jingzhou 434000, China.
authors.forename: Hong-Zhu
authors.initials: HZ
authors.lastname: Lu
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Zhou
mesh_terms: D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D006515:Hepatitis B virus / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D050527:Mesangial Cells / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein
keywords: Extracellular signal-regulated kinase; Glomerulonephritis; Heptitis B virus; Nuclear factor-κB; Tumor necrosis factor-α; X protein