Vidal, Solange, Ludwig, Marie-Gabrielle, Jurisic, Giorgia, Clay, Ieuan, Seuwen, Klaus, DeVallière, Cheryl, Tcymbarevich, Irina, Okoniewski, Michal, Eloranta, Jyrki, Kullak-Ublick, Gerd, Wagner, Carsten and Rogler, Gerhard (2015) The pH-Sensing Receptor OGR1 Improves Barrier Function of Caco-2 Cells and Inhibits Migration in an Acidic Environment. Gastroenterology, 309 (6). G475-90. ISSN 1522-1547

Abstract

Background & Aims
OGR1 (Ovarian Cancer G protein-coupled receptor 1, GPR68), is a proton-sensing receptor responsive to extracellular pH, and its stimulation leads to activation of distinct signaling cascades. Inflammatory bowel disease (IBD) is typically associated with a decrease in local pH, which may lead to altered barrier function and subsequent gastrointestinal repair involving cell adhesion and migration. As the mechanisms underlying the response to pH changes are not well understood, we have investigated OGR1-mediated pH-dependent signaling pathways in intestinal epithelial cells.
Methods
Caco-2 cells stably overexpressing OGR1 were created and validated as tools to study OGR1 signaling. Barrier function, migration and proliferation were measured using ECIS (Electric Cell-Substrate Impedance Sensing) technology. Localization of the tight-junction proteins ZO-1 and occludin, and the rearrangement of cytoskeletal actin were examined by confocal microscopy. Paracellular permeability, protein and gene expression analysis using DNA microarrays were performed on filter-grown Caco-2 monolayers.
Results
Acidic pH shift from pH 7.8 to 6.6 led to improved barrier function and reorganization of F-actin with prominent basal stress fiber formation. Cell migration and proliferation during in vitro wound healing were inhibited. Gene expression analysis revealed significant up-regulation of genes related to cytoskeleton remodeling, cell adhesion, and growth factor signaling.
Conclusion
Acidic extracellular pH can have a signaling function and impact the physiology of intestinal epithelial cells. Deconstructing OGR1-dependent signaling may aid our understanding of mucosal inflammation mechanisms.

Item Type:	Article
Date Deposited:	26 Apr 2016 23:45
Last Modified:	26 Apr 2016 23:45
URI:	https://oak.novartis.com/id/eprint/23819