The Maternal Environment: Influence on Early Mammalian Development

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Principal Objective: Our discovery research will focus on understanding the impact of energy stress metabolism on HIPPO pathway directed cell fate determination during preimplantation development. We will determine whether trophectoderm (TE) and inner cell mass (ICM) cell lineages in the blastocyst vary in their energy metabolism and whether this variation affects differential activation of HIPPO pathway signaling that results in TE differentiation and maintenance of ICM pluripotency. Our hypothesis is that energy metabolism via control of AMPK regulates cell lineage specification via hippo pathway activation during preimplantation development.***The specific objectives are:***1) To investigate the effects of energy stress metabolism on HIPPO pathway activation and TE cell lineage specification.***2) To contrast effects of PI3K, AKT, mTOR and CDK4 inhibition on HIPPO pathway activation in the preimplantation embryo.***3) To investigate glucose deprivation and inhibition of glucose metabolism on HIPPO pathway activation and cell lineage specification in the preimplantation embryo.***4) To investigate targeted downregulation of energy stress mediators on HIPPO pathway activation and cell lineage specification in the preimplantation embryo. ***Short-and Long Term Goals: The short-term goal is to investigate the role that energy metabolism exerts during early mammalian development and to explore its regulation. The long-term goal is to provide an understanding of the influences that the maternal and culture environments place on the developing embryo and then apply this information to optimize embryo culture environments. ***HIPPO pathway: The HIPPO pathway consists of a series of protein kinases including Mst1/2(Hippo); Lats ½(Warts); cofactors Sav1(Salvador) and Mob1a/b (mats); transcriptional cofactors Yap1 and Taz (Yki) and transcription factors TEAD 1-4 (Scalloped). Recent studies demonstrate that HIPPO signaling is active in ICM cells which results in cytoplasmic phosphorylated Yap (Yap-p) that blocks TEAD activity. In the outer cells ie TE progenitors; HIPPO activity is inactivated thus allowing nuclear Yap and TEAD target gene expression resulting in TE cell differentiation. Recent studies have suggested that energy stress metabolism alters HIPPO inactivation in cancer cells. We predict this mechanism is operating in early embryos and that by altering HIPPO pathway activity we should affect cell lineage specification in the early embryo. ***Significance: Research is required to define all of the vital components that support early development. Our experiments will uncover new information regarding the regulation of preimplantation development. This information is required to understand the effects of environmental mediators on embryonic development and to reveal the functional roles of energy stress pathways during preimplantation development.**