Rapid mitogen-activated protein kinase activation by transforming growth factor alpha in wounded rat intestinal epithelial cells

Gastroenterology. 1998 Apr;114(4):697-705. doi: 10.1016/s0016-5085(98)70583-9.


Background & aims: To define signaling events initiating healing after intestinal epithelial injury, activation of mitogen-activated protein kinase (MAPK) pathways was assessed after wounding using an in vitro model.

Methods: Proteins isolated from wounded monolayers of nontransformed intestinal epithelial cells (IEC-6) were analyzed for tyrosine phosphorylation and MAPK expression by Western blot. Extracellular signal-regulated kinase (ERK) 1, ERK2, and Raf-1 activities were assessed by immune complex kinase assays.

Results: Tyrosine phosphorylation of several proteins including ERK1 was substantially increased 5 minutes after injury. Another MAPK, c-Jun-N-terminal protein kinase (JNK), was also activated after wounding. Conditioned medium from wounded but not intact IEC-6 monolayers resulted in increased activity of ERK1, ERK2, and Raf-1 kinase. Wound-conditioned medium stimulated proliferation of subconfluent IEC-6 cells compared with conditioned medium from intact IEC-6 cultures and contained higher amounts of transforming growth factor (TGF)-alpha than supernatants of confluent IEC-6 cultures. Activation of ERK1 and ERK2 was partially inhibited by neutralizing anti-TGF-alpha.

Conclusions: Wounding of intestinal epithelial cells results in activation of Raf-1, ERK1, ERK2, and JNK1 MAPKs and subsequent cell proliferation in vitro. Activation of ERK1 and ERK2 is mediated in part by TGF-alpha.

Publication types

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

MeSH terms

  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • Cells, Cultured
  • Culture Media, Conditioned
  • Enzyme Activation / drug effects
  • Epithelial Cells / enzymology
  • Intestinal Mucosa / enzymology*
  • JNK Mitogen-Activated Protein Kinases*
  • MAP Kinase Kinase 4
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinase Kinases*
  • Mitogen-Activated Protein Kinases*
  • Phosphorylation
  • Protein Kinases / metabolism
  • Rats
  • Transforming Growth Factor alpha / pharmacology*
  • Tyrosine / metabolism


  • Culture Media, Conditioned
  • Transforming Growth Factor alpha
  • Tyrosine
  • Protein Kinases
  • Calcium-Calmodulin-Dependent Protein Kinases
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 4
  • Mitogen-Activated Protein Kinase Kinases