Induction of early response genes in trypsin inhibitor-induced pancreatic growth

Am J Physiol Gastrointest Liver Physiol. 2007 Feb;292(2):G667-77. doi: 10.1152/ajpgi.00433.2006. Epub 2006 Nov 9.

Abstract

Endogenous CCK release induced by a synthetic trypsin inhibitor, camostat, stimulates pancreatic growth; however, the mechanisms mediating this growth are not well established. Early response genes often couple short-term signals with long-term responses. To study their participation in the pancreatic growth response, mice were fasted for 18 h and refed chow containing 0.1% camostat for 1-24 h. Expression of 18 early response genes were evaluated by quantitative PCR; mRNA for 17 of the 18 increased at 1, 2, 4, or 8 h. Protein expression for c-jun, c-fos, ATF-3, Egr-1, and JunB peaked at 2 h. Nuclear localization was confirmed by immunohistochemistry of c-fos, c-jun, and Egr-1. Refeeding regular chow induced only a small increase of c-jun and none in c-fos expression. JNKs and ERKs were activated 1 h after camostat feeding as was the phosphorylation of c-jun and ATF-2. AP-1 DNA binding evaluated by EMSA showed a significant increase 1-2 h after camostat feeding with participation of c-jun, c-fos, ATF-2, ATF-3, and JunB shown by supershift. The CCK antagonist IQM-95,333 blocked camostat feeding-induced c-jun and c-fos expression by 67 and 84%, respectively, and AP-1 DNA binding was also inhibited. In CCK-deficient mice, the maximal response of c-jun induction and AP-1 DNA binding were reduced by 64 and 70%, respectively. These results indicate that camostat feeding induces a spectrum of early response gene expression and AP-1 DNA binding and that these effects are mainly CCK dependent.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Activating Transcription Factor 2 / metabolism
  • Activating Transcription Factor 3 / genetics
  • Activating Transcription Factor 3 / metabolism
  • Animals
  • Carbamates / pharmacology
  • Cholecystokinin / deficiency
  • Cholecystokinin / genetics
  • Early Growth Response Transcription Factors / genetics
  • Early Growth Response Transcription Factors / metabolism
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Gabexate / analogs & derivatives
  • Gabexate / pharmacology
  • Gene Expression / drug effects*
  • Immediate-Early Proteins / genetics*
  • Immediate-Early Proteins / metabolism
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Male
  • Mice
  • Mice, Inbred ICR
  • Mice, Knockout
  • Pancreas / drug effects*
  • Pancreas / growth & development
  • Pancreas / metabolism
  • Phosphorylation / drug effects
  • Protein Binding / drug effects
  • Proto-Oncogene Proteins c-fos / genetics
  • Proto-Oncogene Proteins c-fos / metabolism
  • Proto-Oncogene Proteins c-jun / genetics
  • Proto-Oncogene Proteins c-jun / metabolism
  • Pyrimidinones / pharmacology
  • Receptors, Cholecystokinin / antagonists & inhibitors
  • Transcription Factor AP-1 / metabolism
  • Trypsin Inhibitors / pharmacology*

Substances

  • Activating Transcription Factor 2
  • Activating Transcription Factor 3
  • Atf2 protein, mouse
  • Atf3 protein, mouse
  • Carbamates
  • Early Growth Response Transcription Factors
  • IQM 95333
  • Immediate-Early Proteins
  • Proto-Oncogene Proteins c-fos
  • Proto-Oncogene Proteins c-jun
  • Pyrimidinones
  • Receptors, Cholecystokinin
  • Transcription Factor AP-1
  • Trypsin Inhibitors
  • camostat
  • Gabexate
  • Cholecystokinin
  • Extracellular Signal-Regulated MAP Kinases
  • JNK Mitogen-Activated Protein Kinases