Activation of TGF-β1 promoter by hepatitis C virus-induced AP-1 and Sp1: role of TGF-β1 in hepatic stellate cell activation and invasion

PLoS One. 2013;8(2):e56367. doi: 10.1371/journal.pone.0056367. Epub 2013 Feb 21.

Abstract

Our previous studies have shown the induction and maturation of transforming growth factor-beta 1 (TGF-β1) in HCV-infected human hepatoma cells. In this study, we have investigated the molecular mechanism of TGF-β1 gene expression in response to HCV infection. We demonstrate that HCV-induced transcription factors AP-1, Sp1, NF-κB and STAT-3 are involved in TGF-β1 gene expression. Using chromatin immunoprecipitation (ChIP) assay, we further show that AP-1 and Sp1 interact with TGF-b1 promoter in vivo in HCV-infected cells. In addition, we demonstrate that HCV-induced TGF-β1 gene expression is mediated by the activation of cellular kinases such as p38 MAPK, Src, JNK, and MEK1/2. Next, we determined the role of secreted bioactive TGF-β1 in human hepatic stellate cells (HSCs) activation and invasion. Using siRNA approach, we show that HCV-induced bioactive TGF-β1 is critical for the induction of alpha smooth muscle actin (α-SMA) and type 1 collagen, the markers of HSCs activation and proliferation. We further demonstrate the potential role of HCV-induced bioactive TGF-β1 in HSCs invasion/cell migration using a transwell Boyden chamber. Our results also suggest the role of HCV-induced TGF-β1 in HCV replication and release. Collectively, these observations provide insight into the mechanism of TGF-β1 promoter activation, as well as HSCs activation and invasion, which likely manifests in liver fibrosis associated with HCV infection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Retracted Publication

MeSH terms

  • Animals
  • Base Sequence
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism
  • Cell Line, Tumor
  • DNA Mutational Analysis
  • Furin / metabolism
  • Gene Expression Regulation
  • Genes, Reporter
  • Hepacivirus / physiology*
  • Hepatic Stellate Cells / metabolism
  • Hepatic Stellate Cells / pathology*
  • Hepatic Stellate Cells / virology*
  • Humans
  • Luciferases / metabolism
  • Mink
  • Molecular Sequence Data
  • Promoter Regions, Genetic / genetics*
  • Signal Transduction / genetics
  • Sp1 Transcription Factor / metabolism*
  • Transcription Factor AP-1 / metabolism*
  • Transcriptional Activation / genetics
  • Transforming Growth Factor beta1 / genetics*
  • Transforming Growth Factor beta1 / metabolism
  • Virus Replication

Substances

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • SPZ1 protein, human
  • Sp1 Transcription Factor
  • Transcription Factor AP-1
  • Transforming Growth Factor beta1
  • Luciferases
  • Furin