P2X7 Expression Changes After Injury in Corneal Epithelium

Abstract

Purinergic signaling is an important early event in corneal wound healing. The P2X7 receptor has been shown to play a role in epithelial cell migration after injury in scratch wounds after knockdown with siRNA. We have shown that a truncated variant of P2X7, known for its role in cell death, alters receptor function to promote proliferation after wound healing. Our goal in this study is to determine the regulation of P2X7 expression in a healing cornea. To conduct these studies we used a rat organ culture cornea model and removed 3mm diameter circles of epithelium, leaving the basal lamina intact. After 20 hours the wounds were 80–90% healed, and the cells that migrated into the region and cells back from the leading edge were collected and compared to unwounded epithelium. Total P2X7 was elevated at the leading edge of the wound at 0.5, 4, 10, and 18 hours after injury using immunofluorescence and confocal microscopy. At this time we have not detected any difference in uptake of dye. However, total P2X7 mRNA levels 20 hours after injury are not significantly different from those in unwounded corneas. These data suggest that P2X7 may play a role in cell migration. Variant forms are being investigated. Further investigation may help reveal the mechanisms of P2X7 receptor action at the leading edge of corneal epithelial wounds. Funding for this research is provided by NIH EY06000 and Mass. Lion's Eye Research Fund, Inc.