The aim of this project is to generate important new insights concerning epigenetic factors in oocytes governing reprogramming following somatic cell nuclear transfer (SCNT) and formation and maintenance of the first two lineages in mammalian embryos, the inner cell mass (ICM) and trophectoderm (TE). Our main hypothesis is that experimental modulation of expression levels for the key transcription factors in oocytes will prevent formation of the TE while enhancing the production of the ICM lineage. These alterations should preclude the formation of an embryo while promoting and enhancing donor nucleus reprogramming required for the formation of a single lineage from which pluripotent stem cell lines can be established. We propose the following specific aims: Aim 1. Establish a mouse model of ANT with improved ESC derivation. Initially, we will investigate the effect of siRNA-mediated knockdown of Cdx2, Tead4, and E-Cadherin in mouse oocytes on reprogramming of somatic cells after SCNT. Next, we will examine a cumulative impact of the TE inactivation along with upregulation of critical pluripotent factors - Oct4, Sox2, and Nanog - on reprogramming and derivation of ESCs. Aim 2. Define factors in monkey oocytes that are crucial for TE development. In Experiment 1, we will examine the presence and expression profiles of TEAD4 in monkey oocytes and preimplantation embryos. Next, we will study the role of TEAD4 in monkey oocytes and embryos by morpholino-assisted knockdown. Lastly, fertilized TEAD4-deficient oocytes will be used for ESC isolation. Aim 3: Analyze the roles of key maternal TE factors in epigenetic reprogramming after monkey SCNT. In this aim, we will apply most promising approaches to assess the validity of ANT in the monkey model by first creating CDX2 and TEAD4 depleted oocytes and then conducting SCNT and subsequently deriving ESCs from the resultant pluripotent cells.