Sphingosine-1-phosphate induces COX-2 expression via PI3K/Akt and p42/p44 MAPK pathways in rat vascular smooth muscle cells

J Cell Physiol. 2006 Jun;207(3):757-66. doi: 10.1002/jcp.20621.


Sphingosine 1-phosphate (S1P) has been shown to regulate smooth muscle cell proliferation, migration, and vascular maturation. S1P increases the expression of several proteins including COX-2 in vascular smooth muscle cells (VSMCs) and contributes to arteriosclerosis. However, the mechanisms regulating COX-2 expression by S1P in VSMCs remain unclear. Western blotting and RT-PCR analyses showed that S1P induced the expression of COX-2 mRNA and protein in a time- and concentration-dependent manner, which was attenuated by inhibitors of MEK1/2 (U0126) and PI3K (wortmannin), and transfection with dominant negative mutants of p42/p44 mitogen-activated protein kinases (ERK2) or Akt. These results suggested that both p42/p44 MAPK and PI3K/Akt pathways participated in COX-2 expression induced by S1P in VSMCs. In accordance with these findings, S1P stimulated phosphorylation of p42/p44 MAPK and Akt, which was attenuated by U0126, LY294002, or wortmannin, respectively. Furthermore, this up-regulation of COX-2 mRNA and protein was blocked by a selective NF-kappaB inhibitor helenalin. Consistently, S1P-stimulated translocation of NF-kappaB into the nucleus was revealed by immnofluorescence staining. Moreover, S1P-stimulated activation of NF-kappaB promoter activity was blocked by phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 and helenalin, but not by U0126, suggesting that involvement of PI3K/Akt in the activation of NF-kappaB. COX-2 promoter assay showed that S1P induced COX-2 promoter activity mediated through p42/p44 MAPK, PI3K/Akt, and NF-kappaB. These results suggested that in VSMCs, activation of p42/p44 MAPK, Akt and NF-kappaB pathways was essential for S1P-induced COX-2 gene expression. Understanding the mechanisms involved in S1P-induced COX-2 expression on VSMCs may provide potential therapeutic targets in the treatment of arteriosclerosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Butadienes / pharmacology
  • Cells, Cultured
  • Cyclooxygenase 2 / genetics
  • Cyclooxygenase 2 / metabolism*
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Gene Expression Regulation, Enzymologic / drug effects
  • Lysophospholipids / pharmacology*
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / enzymology*
  • Myocytes, Smooth Muscle / drug effects
  • Myocytes, Smooth Muscle / enzymology*
  • NF-kappa B / metabolism
  • Nitriles / pharmacology
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors
  • Promoter Regions, Genetic / genetics
  • Protein Kinase Inhibitors / pharmacology
  • Protein Transport
  • Proto-Oncogene Proteins c-akt / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • Sphingosine / analogs & derivatives*
  • Sphingosine / pharmacology
  • Transcription, Genetic / genetics


  • Butadienes
  • Lysophospholipids
  • NF-kappa B
  • Nitriles
  • Phosphoinositide-3 Kinase Inhibitors
  • Protein Kinase Inhibitors
  • U 0126
  • sphingosine 1-phosphate
  • Cyclooxygenase 2
  • Proto-Oncogene Proteins c-akt
  • Extracellular Signal-Regulated MAP Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Sphingosine