Reproduction Abstracts

A large number of embryos are produced both in human and domestic animals using assisted reproductive technologies (ART) including in vitro fertilization, but the majority of embryos fail to develop to the blastocyst stage and/or implant during early embryo development. However, the causes of the developmental failures and early miscarriage are not well defined in human and other mammals. Blastocyst stage is critical to the manipulation and/or selection of embryos for embryo transfer (ET) to produce offspring. Studies in animal models, particularly mice, revealed that members of several gene families such as tight junction proteins, claudins, occludins, aquaporins and Na/K ATPases are responsible for the fblastocoel, however the underlying transcriptional mechanisms of these genes are largely unknown. Moreover, the majority of existing research has focused on lineage specific transcript factors (TFs) such as Oct4, Nanog, Sox2, and Cdx2 since establishment of embryonic stem cells. In this context, there is only a limited amount of research in regulation of TFs responsible for genes required for the blastocyst formation including tight junction (TJ) biogenesis and cavity formation. A recent study reported a novel and essential role for transcription activating protein 2 c (Tcfap2c/AP-2γ) in blastocyst formation in a mouse model. The AP-2γ has been shown to regulate a diverse group of gene families critical for TJ biogenesis, ion gradient, water channel and cell proliferation. However, the spatial and temporal expressions of the AP-2γ are not consistent with those in other species, suggesting that a wider and more comparative studies of biological roles and mechanisms of AP-2γ in early embryo development is need.