AQP3 in amniotic epithelial cells: A key mediator of cell survival

Abstract

Objective: To investigate the regulation and functional role of aquaporin 3 (AQP3) in human amniotic epithelial cells in response to osmotic stress. Methods: A human amniotic epithelial cell line (WISH) and human amnion explants were exposed to iso-, hypo-, and hyperosmotic conditions. AQP3 expression was analyzed by RT-qPCR and Western blot. The involvement of TonEBP and NF-κB was examined using specific inhibitors. Cell swelling, viability (MTT), LDH release, Bax/Bcl-2 ratio, and TUNEL staining were evaluated to determine the role of AQP3 in water transport and apoptosis. Results: Hyperosmotic stress induced AQP3 expression in both models through TonEBP activation. NF-κB was also activated, but did not regulate AQP3. AQP3 blocking did not alter cell swelling, indicating a limited role in osmotic water transport. However, AQP3 inhibition or silencing reduced cell viability and increased apoptosis markers under hyperosmotic conditions. These findings suggest a cytoprotective role for AQP3. Conclusion: AQP3 may act as an osmosensitive protein regulated by TonEBP, promoting survival of amniotic epithelial cells during osmotic challenge. Reduced AQP3 expression, as reported in pathological pregnancies such as oligohydramnios, might reflect a failure of this adaptive mechanism, potentially increasing the vulnerability of the amnion to stress-related damage. This may be relevant for understanding the mechanisms leading to membrane rupture in adverse pregnancies.