Fetal Membrane AQP Expression/Amniotic Fluid Regulation

描述（由申请人提供）：羊水（AF）是正常妊娠的基本伴随物，是胎动、生长和发育所必需的。房颤体积过多（羊水过多）或不足（羊水过少）与围产期发病率显著相关。尽管AF体积至关重要，但对导致AF体积异常的机制缺乏了解。AF液体吸收的膜内途径（穿过羊膜）最近被认为是AF再吸收的关键调节途径，对AF体积稳态有重要贡献。然而，水通过羊膜吸收的潜在分子和细胞机制仍然未知。水通道蛋白（Aquaporins，AQP）是一种细胞膜水通道蛋白，能显著增强细胞膜透水性.在迄今为止鉴定的11种哺乳动物水通道蛋白中，我们的研究检测到三种水通道蛋白（AQP 3、8和9）在人和羊的绒毛膜羊膜和胎盘中的表达。原位杂交结果显示，AQP 8在人羊膜上皮细胞、绒毛膜上皮细胞和胎盘滋养层细胞均有表达。此外，研究人员已经证明，AQP 8基因表达维持在人羊膜上皮细胞系中，并且羊膜细胞中的AQP 8基因表达被第二信使cAMP上调。鉴于初步研究，研究者假设AF水吸收通过绒毛膜羊膜中的选择性AQP水通道发生并受其调节。研究者建议：1）描述水道的时间和空间表达（AQP 3、8和9），并将其变化与绵羊整个妊娠期间AF体积动力学的已知变化相关联; 2）研究人和绵羊胎膜中的内分泌催产素、催乳素和第二信使cAMP对人羊膜细胞AQPs基因表达的调控（3）探讨内分泌和cAMP对上皮AQPs基因表达的调节作用，以及对AF体积的影响。我们的目的是确定胎膜水通道蛋白表达的调节机制，并描绘水通道蛋白在房颤稳态中的作用。

DESCRIPTION (provided by applicant): Amniotic fluid (AF) is an essential accompaniment of normal pregnancy, necessary for fetal movement, growth and development. Excess (polyhydramnios) or deficient (oligohydramnios) AF volume is associated with significant perinatal morbidity. Despite the critical importance of AF volume, there is a lack of understanding of mechanism(s), which result in AF volume abnormalities. The intramembranous pathway of AF fluid absorption (across the amniotic membrane) has recently been recognized as a critical regulatory path for AF resorption, contributing importantly to AF volume homeostasis. Yet the underlying molecular and cellular mechanisms for water absorption across the amniotic membranes remain unknown. Aquaporins (AQPs) are cell membrane water channel proteins that greatly enhance cell membrane water permeability. Of the 11 mammalian AQPs identified to date, our studies detected the expression of three AQPs (AQP 3, 8 and 9) in human and ovine chorioamniotic membranes and placenta. In situ hybridization reveals that AQP8 is expressed in epithelial cells of human amnion and chorion, as well as trophoblasts of placenta. In addition, the investigators have demonstrated that AQP8 gene expression is maintained in a human amnion epithelial cell line, and AQP8 gene expression in amnion cells is upregulated by second messenger cAMP. In view of preliminary studies, the investigators hypothesize that AF water absorption occurs via, and is regulated by, select AQP water channels in the chorioamniotic membranes. The investigators propose to: 1) Characterize the temporal and spatial expression of water channels (AQP 3, 8 and 9) in both human and ovine fetal membranes, and correlate its change to known changes in AF volume dynamics throughout pregnancy in sheep; 2) Investigate the endocrine (oxytocin, prolactin) and second messenger camp regulation of AQPs gene expression in human amnion cell line in vitro; and 3) Explore endocrine and cAMP regulation of epithelial AQPs gene expression in vivo and determine the effect on AF volume. Our objective is to determine the regulatory mechanisms of fetal membrane AQP expression and delineate the role of AQPs in AF homeostasis.