Regulation of placental leptin expression by estradiol involves genomic and nongenomic actions

YÉSICA GAMBINO; ANTONIO PÉREZ-PÉREZ; JUAN CALVO CALVO; VÍCTOR SÁNCHEZ MARGALET; CECILIA L. VARONE

Congreso; Reunión anual de la International Federation of Placenta Associations (IFPA); 2010

Leptin is a cytokine-type hormone that controls the functional integrity of feto-placental unit, thereby maintaining pregnancy. Leptin is secreted by placenta, where it plays an autocrine trophic role. However, the regulation of leptin production in the placenta is still poorly understood. In the present study, we analyzed the effect of 17beta-estradiol (E2) on leptin expression in human placental cells.   Methods: BeWo choriocarcinoma cells and human placental explants were used. Western blot analyses were carried out to detect leptin expression as well as the phosphorylated form of proteins involved in different signaling pathways. qPCRs were performed to analyze leptin mRNA levels. Transfection assays with reporter constructs and expression vectors were used to determine transcriptional regulation of leptin.   Results: We have found that leptin expression was increased in both BeWo cells and placental explants, evidencing physiological relevance. Maximal effect was achieved at 100 nM E2 in BeWo cells, and was blocked with 10 nM ICI 182,780. The incubation with E2 also enhanced leptin promoter activity. The overexpression of ESRa, but not of ESRb, increased E2 effect on leptin promoter activity. These effects could be partially explained by membrane ESRs since treatment of cells with E-BSA increased leptin mRNA and protein. This effect was prevented with ICI 182,780. Moreover, the presence of ESRa was detected in membrane fraction of placental cells. On the other hand, E2 and E-BSA induced MAPK and PI3K pathways in placental explants. Inhibition of these signaling pathways with dominant negative mutant kinases or pharmacologic inhibitors prevents E2 effect on leptin expression.  Conclusions: All these findings suggest that E2 enhances leptin expression in human placental cells through genomic and nongenomic actions. These results provide new evidence of the mechanisms wherby E2 regulate leptin expression in placenta and confirm the importance of leptin in trophoblastic physiology