EFFECT OF INTERMITTENT HYPOXIA ON CAVEOLIN-1 EXPRESSION AND ITS ASSOCIATION WITH AQUAPORIN-3 IN VILLOUS TROPHOBLASTS

SZPILBARG, NATALIA; SEYAHIAN, ABRIL; MEDINA, YOLLYSETH; CASTRO-PARODI MAURICIO; MASKIN BERNARDO; DAMIANO, ALICIA E

Ciudad Autonoma de Buenos Aires

Congreso; International Federation of Placenta Associations (IFPA) meeting 2019; 2019

International Federation of Placenta Associations

Objectives: To evaluate the effect of oxygen tension fluctuations on caveolae/caveolin-1 (Cav-1) expression and lipid membrane composition in villous trophoblast, and to analyze the association between aquaporin-3 (AQP3) and Cav-1.Methods: This study was approved by the Ethics Committee of the Hospital Nacional Prof. Dr. Posadas. Normal placental explants were cultured in normoxia and hypoxia/reoxygenation. Cav-1 expression was analyzed by RT-PCR and Western blot. Total lipids from apical (MVM) and basal membrane (BM) vesicles were extracted, total phospholipid amount was determined. Individual phospholipids species were separated by thin layer chromatography and quantified. Cholesterol amount was also determined. In silico analysis of putative Cav-1 binding motifs in AQP3 protein was performed. Cav-1 and AQP3 association was investigated bydouble immunofluorescence and by immunoprecipitation experiments, immobilizing Cav-1 antibody and specifically detecting AQP3.Results: Cav-1 protein and mRNA expression decreased in hypoxia/reoxygenation.Total phospholipid amount increased after hypoxia/reoxygenationtreatment in MVM at the expense of an increase in sphyngomyelin,while cholesterol amount did not change. Membrane fluidity of MVM also decreased. The analysis of the primary structure of AQP3 identified a putativeCav-1 binding site containing the region between the third and fourth transmembrane domains. The presence of AQP3/Cav-1 complex was detected by immunoprecipitation with Cav-1 antibody and confirmed by double immunofluorescence.Conclusion: Protein/protein interactions and regulated incorporation into plasma membrane microdomains may modulate AQPs. Our findings suggest that fluctuations in oxygen tension may alter lipid membrane composition of the trophoblasts, disturbing the ability of sphyngomyelin and cholesterol to assembly into caveolae and reducing Cav-1 expression. Since AQP3 has a role in trophoblast apoptosis, these changes may create an unfavorable environment for AQP3 insertion in the MVM affecting villous trophoblast differentiation and turnover, which may be involved in the development of preeclampsia.