Signaling at the Uterine Placental Interface

PROJECT SUMMARY/ABSTRACT During pregnancy, maternal and extraembryonic cells interact at the uterine-placental interface, facilitating adaptations that promote fetal growth. Trophoblast stem (TS) cells differentiate and invade into the uterus during pregnancy. When invasive trophoblast cells fail to invade and remodel the uterine spiral arteries this leads to obstetrical complications such as early pregnancy loss, preeclampsia, intrauterine growth restriction, and preterm birth. There is little known about the mechanisms of invasive trophoblast cell lineage development. The long-term goal of our research is to identify conserved regulators of invasive trophoblast cell lineage development and its contributions to diseases of pregnancy. We utilize the rat model because like the human it exhibits deep intrauterine trophoblast cell invasion, unlike the shallow invasion observed in the mouse. We also use human TS cells that can be manipulated to differentiate into invasive trophoblast cells, which are known as extravillous trophoblast (EVT) cells in the human. Human TS are a useful model for investigating molecular mechanisms regulating trophoblast cell differentiation. To identify candidate regulators of the invasive trophoblast cell lineage, our lab performed single-cell RNA sequencing (scRNA-seq) of the rat uterine-placental interface. We identified follistatin-like 3 (FSTL3) as a conserved transcript uniquely expressed in invasive trophoblast cells of the rat and human. FSTL3 is an antagonist of activin signaling. Evidence exists for activin and FSTL3 involvement in the regulation of trophoblast cell proliferation, survival, migration, and invasion. In Aim1, we will utilize loss-of-function and gain-of-function approaches to investigate the involvement of activin and FSTL3 in the regulation of human TS cell differentiation into the EVT cell lineage. We will examine structural, transcriptomic, and functional processes affected by activin-FSTL3 dysregulation. In Aim 2, we will evaluate the role of FSTL3 in development of the invasive trophoblast cell lineage within the rat hemochorial placenta. We have generated an FSTL3 null rat model using CRISPR/ Cas9 genome editing. These experiments will permit analysis of the regulatory role of FSTL3 in a physiological context. This project will be completed at the University of Kansas Medical Center (KUMC) under the guidance of Dr. Michael J Soares and a mentoring team of outstanding scientists. A training plan has been formulated to facilitate the development of technical proficiencies and critical thinking skills necessary to devise and execute experimentation that effectively addresses a meaningful biological question. The Soares Laboratory, the Institute for Reproductive and Developmental Sciences, and the Department of Pathology and Laboratory Medicine at KUMC represent a rich scientific environment that will provide the applicant with outstanding graduate training and a research opportunity to gain fundamental new insights into the regulation of female fertility.