Effect of down-regulation of aquaporins in human corneal endothelial and epithelial cell lines

Purpose: The purpose of this study was to determine the effects of down-regulation of Aquaporin 1 (AQP1) and Aquaporin 5 (AQP5) on cell proliferation and migration in human corneal endothelial (HCEC) and human corneal epithelial (CEPI17) cell lines, respectively. Methods: AQP1 and AQP5 were down regulated using siRNA following lipofectamine-mediated transfection in corneal endothelial and epithelial cells, respectively. Down-regulation was confirmed using RT-PCR, indirect immunofluorescence, and immunoblot analysis. Total internal reflection fluorescence (TIRF) microscopy was used to detect cell surface aquaporin expression. Cell proliferation was determined by SRB (sulfrodamine B) assay. Cell migration was determined by in vitro wound healing and migration assay. Results: In HCEC cells, AQP1 was localized to the cytosol as well as cell membrane and its down-regulation resulted in decreased cell proliferation and migration with a significant decrease in phosphorylated ERK (pERK). In CEPI17 cells AQP5 protein expression was also localized to cytosol as well as cell membrane. AQP5 down-regulation resulted in an increase in proliferation and cell migration with no significant difference in pERK. Conclusions: AQP1 plays a role in HCEC proliferation and migration via the ERK signaling pathway and therefore may have significant implications in corneal endothelial dysfunction whereas; AQP5 may play an indirect role in human corneal epithelial cell proliferation and migration.