AQP9 activity in preeclamptic placentas may be associated to a decreased Caveolin-1 expression

LEVI LORENA; DIETRICH VALERIA; CASTRO-PARODI MAURICIO; STERIN-SPEZIALE NORMA; DAMIANO ALICIA E

Los Cocos, Córdoba- Argentina

Simposio; III Latin-American Symposium on Maternal-Fetal Interaction and Placenta:Basic & Clinical Research; 2007

Placental Association of America

Altered placental membrane lipid composition in pregnancy would affect the fetal-maternal exchange. Transcellular water transport across syncytiotrophoblast (hST) may be facilitated by aquaporins (AQPs), water permeable membrane proteins widely expressed in cells and tissues. Previously, we observed an increase of AQP9 expression in preeclamptic (PE) placentas with a lack of functionality of AQP9 for water and mannitol. We also showed that in apical membranes of hST PE placentas sphingomielin augmented 1.5 fold without changes in cholesterol levels. Lipid microdomain enriched in cholesterol and glycosphingolipids can interact with a 21e24 kDa Caveolin-1 (CAV-1) protein forming caveolae. Caveolae are non-coated cell-surface invaginations abundant in many types of cells. It has therefore been proposed that CAV-1 functions as a negative regulator to inhibit the basal activity of many signaling proteins. The aim of this work was to determine if CAV-1 is implicated in the lack of AQP9 functionality in PE placenta. Methods: We determined the expression and localization of CAV-1 and AQP9 in normal and PE placentas. PCR, western blot, immunohistochemistry and confocal microscopy techniques were performed. Results: We observed that CAV-1 localizes in the apical plasma membrane in normal placentas with a decreased expression in PE placentas, not co-localizing with AQP9. Semiquantitative western blot analysis showed that CAV-1 decreased about 2 folds in PE placentas. However, there were no differences in the mRNA expression of CAV-1 gene. Conclusion: As caveolae are implicated in the endocytosis process, our results suggest that the lost of CAV-1 in PE placentas, could reduce AQP9 recycling, leading to an overexpression of an unfunctional protein. Further studies are needed to elucidate the role of CAV-1 in human placenta.