Nitrosative stress in human trophoblast: effect on placental AQP9.

CASTRO-PARODI MAURICIO; MEDINA, YOLLYSETH; DAMIANO, ALICIA E; ANUD, CAROLINA; ABAD, CILIA; DI PAOLA MAURICIO

Congreso; IV International Congress in Translational Medicine; 2018

Maestría Internacional en Ciencias Biomédicas (IMBS).

Introduction: Preeclamptic placentas are associated to an abnormal trophoblast invasion of the spiral arteries resulting in an inadequate utero-placental blood flow. Consequently, an intermittent perfusion is established which leads to an ischemia/reperfusion injury in the syncytiotrophoblast. Fluctuations in O2 tensions may increase the generation of reactive nitrogen species (RNS) by promoting the formation of peroxynitrite (ONOO-) which can modify tyrosine groups of proteins giving rise to the formation of 3-nitrotyrosine (3-NTp). This, can damage lipids, proteins and DNA. Previously we reported that the expression of AQP9 significantly increased in preeclamptic placentas and in normal placental explants exposed to hypoxia/reoxygenation. In both cases, the protein was not functional for water transport. However, the mechanisms involved in the increase of this protein remain unknown.Objective: Our aim was to evaluate the effect of nitrosative stress on placental AQP9 expression and the formation of the 3-NTp-AQP9 in normal and preeclamptic placentas.Methods: This study was approved by the ethics committee of the Hospital Nacional Dr. Prof. A. Posadas. Placental explants were cultured in complete DMEM-F12. In normal placenta explants, nitrosative stress was induced by 100 μM ONOO-. Lipid peroxidation (TBARS) was determined. Expression of superoxide dismutase 1 (SOD-1), as a measure of the antioxidant enzyme defense system, and AQP9 were also studied. The protein level of AQP9 with the 3-NTp post-translational modification was quantified in the trophoblast tissues from preeclamptic placenta and explants exposed to ONOO-. An immunoprecipitation assay, with 3-Nytrotyrosine antibody attached to the column was used to immunoprecipitate the total nitrated proteins. The levels of AQP9 were analyzed in the eluted samples by western blot.Results: We found that the abundance of nitrated AQP9 increased 1.5-fold in preeclamptic placentas compared with normal placentas. In normal placental explants culture in the presence of 100 μM of ONOO- to induced nitrosative stress, the expression of AQP9 also significantly increased 75.42 ± 0.75% compared to control (n=7; p