Differential Expression of Aquaporins During Murine Preimplantation Development

초록

Aquaporins (AQPs) are transmembrane channel proteins, and their function as molecular water channel allows water to flow across plasma membranes in the direction of osmotic gradients. Blastocyst formation is mediated by a trans-trophectoderm ion gradient(s) established, in part, by Na+/K+-ATPase, which drives the movement of water through AQPs across the epithelium into the extracellular space of the blastocyst to form the fluid-filled blastocoel. The purpose of this study was to evaluate the temporal pattern of the expression of AQP-8 and -9 during preimplantation development of mouse embryos. AQP-8 mRNAs were not present in early cleavage stages but were detected in morula and blastocyst stage embryos. On the contrary, AQP-9 mRNAs were expressed in mouse oocytes and embryos up to the blastocyst stage. Real time RT-PCR revealed 2-fold increase during blastocyst development, suggesting these AQPs support expansion of blastocyst. Now we are investigating the effect of cAMP agonist on the expression of AQP-8 and -9 in the blastocysts. In the confocal microscopy, AQP-8 and -9 were localized in membranes of the trophectoderm, suggesting that AQPs may regulate the trophectoderm fluid transport during blastocyst formation.