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Silica-induced TNF-alpha and TGF-beta1 expression in RAW264.7 cells are dependent on Src-ERK/AP-1 pathways

Xiang Li1, Yongbin Hu, Zhongyuan Jin

  • 1Department of Pathology, Xiangya Medical School, Central South University, Changsha 410013, PR China.

Toxicology Mechanisms and Methods
|September 26, 2009
PubMed

Insights

Silica exposure activates Src-ERK/AP-1 pathways in macrophages, leading to increased tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) production, key factors in silicosis pathogenesis.

Area of Science:

  • Immunology
  • Cell Biology
  • Toxicology

Background:

  • Silicosis pathogenesis involves lung macrophage-secreted cytokines like TNF-alpha and TGF-beta1.
  • The precise molecular mechanisms driving silica-induced cytokine expression are not fully understood.

Purpose of the Study:

  • To investigate the involvement of Src-mitogen-activated protein kinase (MAPK)/activator protein-1 (AP-1) signaling in silica-induced TNF-alpha and TGF-beta1 expression.
  • To elucidate the roles of specific kinases (ERK, p38) and transcription factors in this process.

Main Methods:

  • Utilized macrophage cell line (RAW264.7) exposed to silica particles.
  • Employed kinase inhibitors (PP1, PD98059, SB203580) and dominant-negative c-Jun mutant (TAM67).
  • Assessed activation of Src, ERK, p38, AP-1 DNA binding activity, and cytokine expression (TNF-alpha, TGF-beta1).

Main Results:

  • Silica activated Src, p38, and ERK in RAW264.7 cells.
  • Src and ERK inhibition, but not p38 inhibition, suppressed silica-induced TNF-alpha and TGF-beta1.
  • Inhibition of AP-1 DNA binding activity by dominant-negative c-Jun and PD98059 downregulated these cytokines.

Conclusions:

  • The Src-ERK/AP-1 signaling pathway is crucial for silica-induced TNF-alpha and TGF-beta1 expression in macrophages.
  • These findings provide insights into the molecular mechanisms of silicosis.
  • Targeting this pathway may offer therapeutic strategies for silicosis.

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