The Role of Protease-Activated Receptor-2 During Wound Healing in Intestinal Epithelial Cells
Creators: name: Fernando, Elizabeth
Publisher: name: Graduate Studies
Year: 2017
Subjects: subject: Biology--Cell
subject: Biology--Molecular
subject: Physiology
subject: FOS: Biological sciences
subject: protease
subject: protease-activated receptor
subject: PAR2
subject: Inflammatory Bowel Disease
subject: intestinal barrier
subject: gastrointestinal
subject: epithelial
subject: wound healing
subject: cell migration
subject: restitution
subject: lamellipodia
subject: actin regulation
subject: E-cadherin
subject: cyclooxygenase
subject: COX-2
subject: prostaglandin
subject: primary epithelial cell
subject: RNA sequencing

description: The intestinal epithelial barrier is a single layer of epithelial cells that functions to regulate absorption and secretion, in addition to protecting our bodies from the contents of the intestinal lumen. When the barrier becomes damaged, uncontrolled passage of bacterial and antigenic factors generates an immune response that can result in intestinal inflammation. One principal step in the resolution of inflammation is epithelial barrier healing, which stops the entry of inflammatory triggers. The mechanisms of intestinal epithelial wound healing are not completely understood, especially in the context of proteases and their receptors. The intestinal epithelial barrier is exposed to numerous proteases originating from luminal bacteria, host immune cells, and proteases expressed by the epithelial cells themselves. It was recently shown that activation of protease-activated receptor-2 (PAR2) on epithelial cells induced the expression of cyclooxygenase-2 (COX-2), which has protective functions in the gastrointestinal tract. It was hypothesized that PAR2-induced COX-2 could enhance wound healing in intestinal epithelial cells. In the first part of this study, PAR2-induced COX-2 was characterized using western blotting and ELISA techniques to perform time-course and dose-response experiments. Actinomycin D was used to determine that PAR2-induced COX-2 was transcriptionally regulated. Potential components of the PAR2-COX-2 signaling pathway, including Rac1 and CUX1, were studied using pharmacological inhibitors and siRNA. However, both Rac1 and CUX1 were not involved in the PAR2-COX-2 signaling pathway. In the second part of this study, the Caco2 cell model was used for epithelial wound healing. Contrary to our hypothesis, PAR2 activation inhibited wound healing, independently of COX-2 activity. The inhibition of wound healing was due to reduced migration associated with a PAR2-mediated reduction in lamellipodia formation at the wound edge, and an increase in E-cadherin expression surrounding the wound. Conversely, when wound healing was investigated in T84 intestinal epithelial cells, PAR2 activation was found to enhance wound healing through increased cell migration, with opposite effects on actin dynamics and E-cadherin expression compared to the data obtained from Caco2 cells. These findings represent a novel effect of PAR2 activation on the mechanisms of epithelial cell wound healing that could influence the resolution of intestinal inflammation.