CONICET | Buscador de Institutos y Recursos Humanos

OBJECTIVE: To explore the expression of AQP9 in the heavy/large and light/small mitochondrial subpopulations that coexist in the villous trophoblast of term placenta.MATERIAL AND METHODS: This study was approved by the ethics committee of Hospital Nacional Prof. Dr. A. Posadas. Human chorionic villi were fragmented, and tissue was shaken in HES buffer (10 mM HEPES-KOH, 0.1 mM EGTA, 250 mM sucrose), pH 7.4, with protease inhibitors. Differential centrifugation was performed to obtain mitochondrial, microsomal and cytosolic fractions. From mitochondrial fraction, heavy/large and light/small mitochondrial populations were also isolated by differential centrifugation. Localization was confirmed by immunofluorescence assay.RESULTS: Our results showed for the first time the expression and localization of AQP9 in mitochondria of villous trophoblast from normal term placentas. In addition, we only found that AQP9 was expressed in the heavy/large mitochondrial subpopulation. CONCLUSIONS:Mitochondria dominate the process of life-and-death decisions of the cell. Mitochondrial populations present different morphologic and metabolic states and it was proposed that the heavy/large fraction is involved in apoptosis while the light/small fraction is related to necroptosis, necrosis or autophagy. AQP9 can function not only as a water channel but also as a peroxiporin. The presence of AQP9 in the heavy mitochondria fraction suggest that this protein may contribute to the regulation of mitochondrial matrix volume and facilitate the mitochondrial H2O2 release. Thus, an abnormal AQP9 expression may exacerbated oxidative stress and cell death, triggering pathological situations such as preeclampsia. Further studies are required to elucidate the role of AQP9 in villous trophoblast mitochondria.