Ceramide regulates the transcription of cyclooxygenase-2: Evidence for involvement of extracellular signal-regulated kinase/c-Jun N-terminal kinase and p38 mitogen-activated protein kinase pathways Academic Article Article uri icon

Overview

MeSH Major

  • Adiponectin
  • Adipose Tissue, White
  • Aromatase
  • Breast
  • C-Reactive Protein
  • Interleukin-6
  • Leptin
  • Menopause

abstract

  • The ceramide signaling pathway is activated by the sphingomyelinase (SMase)-mediated hydrolysis of cell membrane sphingomyelin to ceramide. We determined whether ceramide, a lipid second messenger, induced cyclooxygenase-2 (COX-2) in human mammary epithelial cells. Treatment of cells with neutral SMase or C2- or C6-ceramide enhanced prostaglandin E2 synthesis and increased levels of COX-2 protein and mRNA. Nuclear runoff assays revealed increased rates of COX-2 transcription after treatment with SMase and C2- and C6-ceramide. Transient transfections utilizing COX-2 promoter deletion constructs and COX-2 promoter constructs in which specific enhancer elements were mutagenized indicated that the effects of ceramide were mediated via a cAMP response element. The induction of COX-2 by ceramide was inhibited by calphostin C, an inhibitor of protein kinase C. Induction of COX-2 promoter activity by SMase was blocked by overexpressing kinase-deficient Raf-1. Triggering of the ceramide pathway also led to increases in extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) activities; pharmacological inhibitors of MAPK kinase (MEK) and p38 MAPK blocked the induction of COX-2 by SMase. Overexpressing ERK1, JNK, or p38 led to severalfold increases in COX-2 promoter activity. By comparison, overexpression of dominant negatives for ERK1/2, JNK, or p38 blocked the activation of COX-2 promoter activity by SMase. A dominant negative for c-Jun inhibited the activation of COX-2 promoter activity by ceramide. Thus, in response to ceramide, increased MAPK signaling activates c-Jun, which, in turn, induces COX-2 gene expression via the cAMP response element in the COX-2 promoter.

publication date

  • December 4, 1998

Research

keywords

  • Academic Article

Identity

Digital Object Identifier (DOI)

  • 10.1074/jbc.273.49.32943

PubMed ID

  • 9830045

Additional Document Info

start page

  • 32943

end page

  • 9

volume

  • 273

number

  • 49