Alterations in subcellular localization of p38 MAPK potentiates endothelin-stimulated COX-2 expression in glomerular mesangial cells

J Biol Chem. 2003 Dec 19;278(51):51928-36. doi: 10.1074/jbc.M309256200. Epub 2003 Oct 6.


Endothelin-1 (ET-1) is a potent vasoconstrictor peptide with mitogenic actions linked to activation of tyrosine kinase signaling pathways. ET-1 induces cyclooxygenase-2 (COX-2), an enzyme that converts arachidonic acid to pro-inflammatory eicosanoids. Activation of each of the three major mitogen-activated protein kinase (MAPK) pathways, ERK1/2, JNK/SAPK, and p38 MAPK (p38), have been shown to enhance the expression of COX-2. Negative regulation of MAPK may occur via a family of dual specificity phosphatases referred to as mitogen-activated protein kinase phosphatases (MKP). The goal of this work was to test the hypothesis that wild type MKP-1 regulates the expression of ET-1-induced COX-2 expression by inhibiting the activation of p38 in cultured glomerular mesangial cells (GMC). An adenovirus expressing both wild type and a catalytically inactive mutant of MKP-1 (MKP-1/CS) were constructed to study ET-1-regulated MAPK signaling and COX-2 expression in cultured GMC. ET-1 stimulated the phosphorylation of ERK and p38 alpha MAPK and induced the expression of COX-2. Expression of COX-2 was partially blocked by U0126, a MEK inhibitor, and SB 203580, a p38 MAPK inhibitor. Adenoviral expression of MKP-1/CS augmented basal and ET-1-induced phosphorylation of p38 alpha MAPK with less pronounced effects on ERK1/2 phosphorylation. Ectopic expression of wild type MKP-1 blocked the phosphorylation of p38 alpha MAPK by ET-1 but increased the phosphorylation of p38 gamma MAPK. Co-precipitation studies demonstrated association of MKP-1 with p38 alpha MAPK and ERK1/2. Immunofluorescent image analysis demonstrated trapping of phospho-p38 MAPK in the cytoplasm by MKP-1/CS/green fluorescent protein. ET-1-stimulated expression of COX-2 was increased in MKP-1/CS versus LacZ or green fluorescent protein-infected control cells. These results indicate that MKP-1 demonstrates a relative selectivity for p38 alpha MAPK versus p38 gamma MAPK in GMC and is likely to indirectly regulate the expression of COX-2.

Publication types

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

MeSH terms

  • Animals
  • Cell Cycle Proteins*
  • Cells, Cultured
  • Cyclooxygenase 2
  • Dual Specificity Phosphatase 1
  • Endothelin-1 / pharmacology*
  • Gene Expression Regulation / drug effects
  • Glomerular Mesangium / cytology*
  • Immediate-Early Proteins / metabolism
  • Immediate-Early Proteins / physiology
  • Isoenzymes / biosynthesis*
  • Mitogen-Activated Protein Kinases / antagonists & inhibitors
  • Mitogen-Activated Protein Kinases / metabolism*
  • Phosphoprotein Phosphatases*
  • Phosphorylation
  • Prostaglandin-Endoperoxide Synthases / biosynthesis*
  • Protein Binding
  • Protein Phosphatase 1
  • Protein Transport
  • Protein Tyrosine Phosphatases / metabolism
  • Protein Tyrosine Phosphatases / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • p38 Mitogen-Activated Protein Kinases


  • Cell Cycle Proteins
  • Endothelin-1
  • Immediate-Early Proteins
  • Isoenzymes
  • Cyclooxygenase 2
  • Prostaglandin-Endoperoxide Synthases
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Phosphoprotein Phosphatases
  • Protein Phosphatase 1
  • Dual Specificity Phosphatase 1
  • Dusp1 protein, rat
  • Protein Tyrosine Phosphatases