Analysis of transcription factor AP-2 expression and function during mouse preimplantation development.

The activating protein 2 (AP-2) transcription factor family is required for multiple aspects of mouse postimplantation development, but much less is known about the expression and possible function of these genes during the preimplantation period. In the present study, we have examined the expression of all five members of the mouse AP-2 gene family in the unfertilized oocyte and from zygote formation to the blastocyst stage of development. Four AP-2 genes are differentially expressed during the preimplantation period,Tcfap2a, Tcfap2b, Tcfap2c, and Tcfap2e. Furthermore, with the exception of Tcfap2a, these genes are also expressed in unfertilized oocytes, indicating that they may be important for oogenesis, maternal-effect functions, or both. Given these findings, we have initiated studies to assess how various combinations of maternal and zygotic AP-2 gene expression might function together to regulate pre- and peri-implantation development. The present study focuses on the interplay between the expression of zygotic Tcfap2aand maternal and zygoticTcfap2c. These studies indicate that zygotic, but not maternal, Tcfap2cexpression is required for normal embryogenesis. In addition, the combined loss of both Tcfap2a and Tcfap2caccelerates embryonic lethality compared to the loss of either gene alone, demonstrating that genetic redundancy exists between these two AP-2 family members during the peri-implantation period of embryogenesis.