Antiapoptotic effects of leptin in trophoblasts

AYELÉN TORO; MALENA SCHANTON; JULIETA L. MAYMÓ; ANTONIO PÉREZ PÉREZ; BERNARDO MASKIN; VÍCTOR SÁNCHEZ MARGALET; CECILIA L. VARONE

Simposio; VI SLIMP- Latin American Symposium on Maternal Fetal Interaction & Placenta; 2015

Leptin produced by the placenta has many roles as an autocrine hormone. We have previously demonstrated that leptin promotes proliferation and survival of trophoblastic cells. In the present work we aimed to study the mechanisms that mediate the antiapoptotic effect of leptin in placenta. Methods: BeWo and Swan cells, cultured under standard conditions, as well as human placental explants were used. Western blot, qRT-PCR and transfection assays with reporter constructs and expression vectors were carried out. All procedures were approved by ethical review committee at the A Posadas National Hospital.Results: Recombinant human leptin added to BeWo cell line and human placental explants, showed a decrease on Caspase-3 activation in a dose dependent manner. Moreover, inhibition of endogenous leptin expression with 2 M of an antisense oligonucleotide, reversed Caspase-3 diminution. We also found that the cleavage of Poly [ADP-ribose] polymerase-1 (PARP-1) was diminished in the presence of leptin. Placental explants cultivated in the absence of serum in the culture media increased the apoptotic cleavage of DNA and this effect was prevented by the addition of 100 ng leptin/ml. We found that under serum deprivation conditions, leptin increased the anti-apoptotic Bcl-2 protein expression, while downregulated the pro-apoptotic Bax and Bid proteins expression in Swan-71 cells and placental explants. In both models leptin augmented Bcl-2/Bax ratio. Moreover we have demonstrated that p53, one of the key cell cycle-signaling proteins, is downregulated in the presence of leptin under serum deprivation. Leptin also reduced the phosphorylation of Ser-46 p53 that plays a pivotal role for apoptotic signaling by p53 and augments the levels of Mdm2 protein, a regulator of p53 half life. Furthermore, leptin antiapoptotic effect and p53 regulation by leptin, involved MAPK and PI3K signaling pathways. Conclusions:These results improve the comprehension of leptin function during pregnancy and further support the importance of leptin in pregnancy.