Apical and basolateral pools of proteinase-activated receptor-2 direct distinct signaling events in the intestinal epithelium

Am J Physiol Cell Physiol. 2011 Jan;300(1):C113-23. doi: 10.1152/ajpcell.00162.2010. Epub 2010 Nov 10.

Abstract

Studies suggest that there are two distinct pools of proteinase-activated receptor-2 (PAR₂) present in intestinal epithelial cells: an apical pool accessible from the lumen, and a basolateral pool accessible from the interstitial space and blood. Although introduction of PAR₂ agonists such as 2-furoyl-LIGRL-O-NH₂ (2fAP) to the intestinal lumen can activate PAR₂, the presence of accessible apical PAR₂ has not been definitively shown. Furthermore, some studies have suggested that basolateral PAR₂ responses in the intestinal epithelium are mediated indirectly by neuropeptides released from enteric nerve fibers, rather than by intestinal PAR₂ itself. Here we identified accessible pools of both apical and basolateral PAR₂ in cultured Caco2-BBe monolayers and in mouse ileum. Activation of basolateral PAR₂ transiently increased short-circuit current by activating electrogenic Cl⁻ secretion, promoted dephosphorylation of the actin filament-severing protein, cofilin, and activated the transcription factor, AP-1, whereas apical PAR₂ did not. In contrast, both pools of PAR₂ activated extracellular signal-regulated kinase 1/2 (ERK1/2) via temporally and mechanistically distinct pathways. Apical PAR₂ promoted a rapid, biphasic PLCβ/Ca²(+)/PKC-dependent ERK1/2 activation, resulting in nuclear localization, whereas basolateral PAR₂ promoted delayed ERK1/2 activation which was predominantly restricted to the cytosol, involving both PLCβ/Ca²(+) and β-arrestin-dependent pathways. These results suggest that the outcome of PAR₂ activation is dependent on the specific receptor pool that is activated, allowing for fine-tuning of the physiological responses to different agonists.

Publication types

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

MeSH terms

  • Animals
  • Caco-2 Cells
  • Chlorides / metabolism
  • Extracellular Signal-Regulated MAP Kinases / genetics
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Female
  • GTP-Binding Protein alpha Subunits, Gq-G11 / genetics
  • GTP-Binding Protein alpha Subunits, Gq-G11 / metabolism
  • Gene Expression Regulation / physiology
  • Humans
  • Ileum / physiology
  • Intestinal Mucosa / cytology*
  • Intestinal Mucosa / physiology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Receptor, PAR-2 / genetics
  • Receptor, PAR-2 / metabolism*
  • Signal Transduction / physiology*

Substances

  • Chlorides
  • Receptor, PAR-2
  • Extracellular Signal-Regulated MAP Kinases
  • GTP-Binding Protein alpha Subunits, Gq-G11