Mitogen-activated protein kinase and its activator are regulated by hypertonic stress in Madin-Darby canine kidney cells

J Clin Invest. 1994 Jun;93(6):2387-92. doi: 10.1172/JCI117245.


Madin-Darby canine kidney cells behave like the renal medulla and accumulate small organic solutes (osmolytes) in a hypertonic environment. The accumulation of osmolytes is primarily dependent on changes in gene expression of enzymes that synthesize osmolytes (sorbitol) or transporters that uptake them (myo-inositol, betaine, and taurine). The mechanism by which hypertonicity increases the transcription of these genes, however, remains unclear. Recently, it has been reported that yeast mitogen-activated protein (MAP) kinase and its activator, MAP kinase-kinase, are involved in osmosensing signal transduction and that mutants in these kinases fail to accumulate glycerol, a yeast osmolyte. No information is available in mammals regarding the role of MAP kinase in the cellular response to hypertonicity. We have examined whether MAP kinase and MAP kinase-kinase are regulated by extracellular osmolarity in Madin-Darby canine kidney cells. Both kinases were activated by hypertonic stress in a time- and osmolarity-dependent manner and reached their maximal activity within 10 min. Additionally, it was suggested that MAP kinase was activated in a protein kinase C-dependent manner. These results indicate that MAP kinase and MAP kinase-kinase(s) are regulated by extracellular osmolarity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Cells, Cultured
  • Dogs
  • Enzyme Activation
  • Kidney / enzymology
  • Mitogen-Activated Protein Kinase Kinases
  • Osmolar Concentration
  • Protein Kinase C / physiology
  • Protein Kinases / metabolism*


  • Protein Kinases
  • Protein Kinase C
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinase Kinases