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Mast cell tryptase regulates rat colonic myocytes through proteinase-activated receptor 2

C U Corvera1, O Déry, K McConalogue

  • 1Department of Surgery, University of California, San Francisco, San Francisco, California 94143-0660, USA.

The Journal of Clinical Investigation
|September 18, 1997
PubMed

Insights

Proteinase-activated receptor-2 (PAR-2) is found in colon muscle cells and activated by mast cell tryptase. PAR-2 activation reduces colon contractions, potentially impacting motility during mast cell degranulation.

Area of Science:

  • Gastroenterology
  • Cell Biology
  • Pharmacology

Background:

  • Proteinase-activated receptor-2 (PAR-2) is a G protein-coupled receptor.
  • PAR-2 is highly expressed in small intestinal enterocytes and activated by luminal trypsin.
  • The role of PAR-2 in the colon remains largely unknown.

Purpose of the Study:

  • To investigate the localization, activation, and function of PAR-2 in the rat colon.
  • To determine the cellular expression of PAR-2 in colonic tissues.
  • To elucidate the effect of PAR-2 activation on colonic myocyte function and contractility.

Main Methods:

  • Immunofluorescence and RT-PCR were used to localize and confirm PAR-2 expression in rat colon myocytes.
  • Primary myocyte cultures were stimulated with trypsin, SLIGRL-NH2, mast cell tryptase, and mast cell filtrate.
  • Intracellular calcium ([Ca2+]i) levels were measured, and the effects of PAR-2 activation on colonic strip contractions were assessed.
  • Specific inhibitors and receptor antagonists were employed to identify signaling pathways.

Main Results:

  • PAR-2 was localized to the muscularis externa of the rat colon and expressed by myocytes.
  • Mast cell tryptase and other activators increased intracellular calcium in myocytes.
  • PAR-2 activation by tryptase was confirmed using a specific inhibitor (BABIM) and desensitization.
  • Activation of PAR-2 significantly inhibited the amplitude of colonic rhythmic contractions.

Conclusions:

  • PAR-2 is highly expressed by colonic myocytes and can be activated by mast cell tryptase.
  • PAR-2 activation in the colon leads to decreased myocyte contractility.
  • Mast cell-derived PAR-2 activation may contribute to colonic motility disturbances.

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