Lipopolysaccharide stimulation of ERK1/2 increases TNF-alpha production via Egr-1

Am J Physiol Cell Physiol. 2002 Jun;282(6):C1205-11. doi: 10.1152/ajpcell.00511.2001.

Abstract

Lipopolysaccharide (LPS) is a potent activator of tumor necrosis factor-alpha (TNF-alpha) production by macrophages. LPS stimulates the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and increases TNF-alpha mRNA and protein accumulation in RAW 264.7 murine macrophages. However, the role of ERK1/2 activation in mediating LPS-stimulated TNF-alpha production is not well understood. Inhibition of ERK1/2 activation with PD-98059 or overexpression of dominant negative ERK1/2 decreased LPS-induced TNF-alpha mRNA quantity. LPS rapidly increased early growth response factor (Egr)-1 binding to the TNF-alpha promoter; this response was blunted in cells treated with PD-98059 or transfected with dominant-negative ERK1/2. Using a chloramphenicol acetyltransferase reporter gene linked to the Egr-1 promoter, we show that LPS increased Egr-1 promoter activity via an ERK1/2-dependent mechanism. These results delineate the role of ERK1/2 activation of Egr-1 activity in mediating LPS-induced increases in TNF-alpha mRNA expression in macrophages.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Line
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Early Growth Response Protein 1
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Flavonoids / pharmacology
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / genetics
  • Genes, Dominant
  • Genes, Reporter
  • Immediate-Early Proteins*
  • Lipopolysaccharides / pharmacology*
  • Macrophages / cytology
  • Macrophages / drug effects
  • Macrophages / metabolism*
  • Mice
  • Mitogen-Activated Protein Kinase 1 / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase 1 / genetics
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism*
  • Phosphorylation / drug effects
  • Promoter Regions, Genetic / physiology
  • RNA, Messenger / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transfection
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism*

Substances

  • DNA-Binding Proteins
  • Early Growth Response Protein 1
  • Egr1 protein, mouse
  • Enzyme Inhibitors
  • Flavonoids
  • Immediate-Early Proteins
  • Lipopolysaccharides
  • RNA, Messenger
  • Transcription Factors
  • Tumor Necrosis Factor-alpha
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one