Expression of aquaporin 9 in human chorioamniotic membranes and placenta.
OBJECTIVE
Aquaporin 9 (AQP9) is one of the recently identified water channels that is also permeable to neutral solutes including urea. To investigate the molecular mechanism of intramembranous pathway of amniotic fluid regulation, we sought to determine whether AQP9 is expressed, and the cellular localization of AQP9 expression in human fetal membranes.


METHODS
Fetal membranes from 5 normal term human pregnancies were studied. Northern analysis was used to determine the tissue AQP9 messenger RNA (mRNA) expression. In situ hybridization and immunohistochemical staining with specific anti-AQP9 antibody was used for cellular AQP9 localization in the human fetal membranes.


RESULTS
Northern analysis detected AQP9 mRNA expression in human amnion, chorion, and placenta. In situ hybridization revealed AQP9 mRNA expression in epithelial cells of the amnion, chorion cytotrophoblasts, and syncytiotrophoblasts and cytotrophoblasts of placenta. Further immunohistochemical study confirmed the AQP9 protein expression in these cell types of fetal membranes.


CONCLUSIONS
This study demonstrated the expression of AQP9 mRNA and protein in human chorioamniotic membranes and placenta. The AQP9 expression in fetal membranes suggests that AQP9 may be an important water channel in intramembranous amniotic fluid water regulation.
Wang
Shengbiao
S
Harbor-UCLA Medical Center, 1000 W Carson St, Box 3, Torrance, CA 90502, USA. sheng@gcrc.rei.edu
Chen
Jiexiong
J
Beall
Marie
M
Zhou
Weidong
W
Ross
Michael G
MG
D000328:Adult; D000650:Amnion / Q000502:physiology*; D000653:Amniotic Fluid / Q000378:metabolism; D020346:Aquaporins / Q000235:genetics*; D015152:Blotting, Northern; D002585:Cesarean Section; D002823:Chorion / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D047929:Term Birth
C109669:AQP9 protein, human; D020346:Aquaporins; D012333:RNA, Messenger