Epithelial injury induces Egr-1 and Fos expression by a pathway involving protein kinase C and ERK

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Abstract

The signaling pathways activated in response to gastrointestinal injury remain poorly understood. Previous work has implicated the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase as a mediator of wound-signal transduction and a possible regulator of epithelial restitution. Monolayer injury resulted in rapid activation of p42 and p44 ERK. Injury-induced ERK activation was blocked by protein kinase C inhibition or by disruption of the cell cytoskeleton. Significant increases in Fos and early growth response (Egr)-1 mRNA levels were stimulated by injury, peaking by 20 min. ERK activation and the induction of Egr-1 mRNA were inhibited in a dose-dependent fashion with PD-98059. Fos mRNA expression was partially blocked by PD-98059. Western blot analysis demonstrated strong expression and nuclear localization of Fos and Egr after wounding. Electrophoretic mobility shift assays demonstrated that nuclear extracts contained a protein that specifically bound double-stranded oligonucleotides containing the Egr consensus binding element. Gel supershift assays demonstrated that the protein-DNA complexes were recognized by anti-Egr antibody. Inhibition of injury-induced ERK activation by PD-98059 or direct interference with Egr by expression of a dominant negative mutant led to significantly reduced in vitro monolayer restitution.

Original languageEnglish
Pages (from-to)G322-G330
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume276
Issue number2 39-2
DOIs
StatePublished - Feb 1999

Keywords

  • Early growth response-1
  • Extracellular signal-regulated kinase
  • Injury
  • Mitogen-activated protein kinase
  • Restitution

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