Functional and molecular expression of AQP9 channel and UT-A transporter in normal and preeclamptic human placentas.
Transcellular flux of urea across human placenta may be facilitated by aquaglyceroporins and/or by urea transporters (UT). Previously we have reported the presence of AQP3 and AQP9 in the syncytiotrophoblast of human term placenta (hST). In the present study, we detected a significant uptake of water, urea and mannitol sensitive to mercury and phloretin in explants from normal term placenta, which indicates a functional AQP9. In addition, we observed an increase of AQP9 expression in preeclamptic placenta with a lack of functionality of AQP9 for water and mannitol. Our data showed a molecular and functional expression of UT-A in hST from normal and preeclamptic placentas. In the last case, urea uptake sensitive to phloretin and mercury increased and the UT-A protein seems to be augmented. These results suggest that the increase of urea uptake in preeclamptic pregnancies could be attributed to an increase of expression of UT-A more than AQP9 proteins. In conclusion, our results provide new evidences that suggest the involvement of AQP9 and UT-A in the urea excretion mechanism across hST from mother to fetus in physiological conditions. Much further work is needed to define whether the overexpression of AQP9 plays a direct role either in the pathogenesis or in the adaptative response of preeclampsia.
Damiano
A E
AE
Laboratorio de Fisiopatogenia, Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155, 7mo piso, 1121 Buenos Aires, Argentina.
Zotta
E
E
Ibarra
C
C
D000595:Amino Acid Sequence; D020346:Aquaporins / Q000096:biosynthesis*; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D008353:Mannitol / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D010920:Placenta / Q000378:metabolism*; D011225:Pre-Eclampsia / Q000378:metabolism*; D011247:Pregnancy; D014327:Trophoblasts / Q000378:metabolism; D014508:Urea / Q000378:metabolism; D014867:Water / Q000378:metabolism; D000096982:Urea Transporters
D020346:Aquaporins; D008353:Mannitol; D026901:Membrane Transport Proteins; D014508:Urea; D014867:Water; D000096982:Urea Transporters; C109669:AQP9 protein, human