Both ERK and JNK are required for enhancement of MD-2 gene expression during differentiation of HL-60 cells

Biol Cell. 2008 Jun;100(6):365-75. doi: 10.1042/BC20070140.

Abstract

Background information: MD-2 is associated with the extracellular domain of TLR4 (Toll-like receptor 4) and augments TLR4-dependent LPS (lipopolysaccharide) responses in vitro. Our previous investigation found that PMA-induced HL-60 cell differentiation to macrophages is associated largely with TLR2 and CD14 and, to a much lesser extent, with TLR4.

Results: We studied the MD-2 expression during differentiation of HL-60 cells induced by PMA. The results showed that PMA, but not VitD(3) (1alpha,25-dihydroxy-vitamin D(3)), strongly induces MD-2 gene expression by HL-60 cells in a time- and dose-dependent manner. Treatment with an MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase] inhibitor (PD98059) and a JNK (c-Jun N-terminal kinase) inhibitor (SP600125) suppresses PMA-induced MD-2 gene expression, whereas impairment of p38 function by treatment with the inhibitor SB203580 has no effect on MD-2 mRNA. In order to reveal the possible molecular mechanism for such a regulation of MD-2 gene expression, we cloned and analysed the putative MD-2 gene promoter. Transient transfection of different deletion mutants demonstrated that the region -185/-171 (5'-TCCTTTACAGGAAGT-3') of the MD-2 gene promoter is closely related to gene transcription in response to PMA. Additionally, the transcription factor Elk-1 has been found to bind this specific motif.

Conclusions: These results suggest that ERK and JNK pathways are involved in PMA-mediated MD-2 gene expression during HL-60 cell differentiation, and the activation of the MEK/possible ERK/Elk signal pathway is the mechanism responsible for PMA-induced MD-2 gene expression in differentiated HL-60 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Differentiation* / drug effects
  • Extracellular Signal-Regulated MAP Kinases / antagonists & inhibitors
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Gene Expression* / drug effects
  • HL-60 Cells
  • Humans
  • JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • JNK Mitogen-Activated Protein Kinases / metabolism*
  • Lymphocyte Antigen 96 / genetics*
  • Lymphocyte Antigen 96 / metabolism
  • Promoter Regions, Genetic
  • Protein Kinase Inhibitors / pharmacology
  • Signal Transduction
  • Tetradecanoylphorbol Acetate / pharmacology
  • Transcription Factors / metabolism
  • ets-Domain Protein Elk-1 / metabolism

Substances

  • ELK1 protein, human
  • LY96 protein, human
  • Lymphocyte Antigen 96
  • Protein Kinase Inhibitors
  • Transcription Factors
  • ets-Domain Protein Elk-1
  • Extracellular Signal-Regulated MAP Kinases
  • JNK Mitogen-Activated Protein Kinases
  • Tetradecanoylphorbol Acetate