All-Trans Retinoic Acid Increases Aquaporin 3 Expression in Human Vaginal Epithelial Cells

INTRODUCTION: Water channel aquaporin 3 (AQP3) is an aquaglyceroporin that transports small neutral solutes and water. All-trans retinoic acid (ATRA), a member of the retinoid drug class, acts as a regulator in several biological processes. AIM: To investigate the effect of ATRA on the expression of AQP3 in human vaginal epithelial cells. METHODS: Human vaginal mucosal epithelial cells (CRL2616) were treated with ATRA 0, 0.01, 0.1, and 1 μmol/L for 24 hours to examine the dose-dependent effects of ATRA and with ATRA 1 μmol/L for 0, 3, 6, 12, and 24 hours. MAIN OUTCOME MEASURES: The expression of AQP3 and retinoic acid receptor (RAR) was determined by western blot analysis and reverse transcription polymerase chain reaction. RESULTS: AQP3 was detected in the cell membrane of human vaginal epithelial cells. ATRA increased the protein expression and mRNA levels of AQP3 in a dose-dependent manner (P < .05). ATRA also increased the protein expression of RARα (P < .05). Treatment of CRL2616 cells with an RAR antagonist (Ro 41-5253) significantly decreased AQP3 protein expression (P < .05). CONCLUSION: ATRA mediated by RARα increased AQP3 gene and protein expression in human vaginal mucosal epithelial cells. These results imply that AQP3 regulated by ATRA could play an important role in the mechanism of vaginal lubrication.