Defining the link between trisomy 21 and placentation defects - down's syndrome (T21) is the most common aneuploidy disorder in humans

T21 pregnancies are at an increased risk of adverse pregnancy outcomes including stillbirth and intrauterine growth restriction resulting from placental insufficiency. T21 is also accompanied by comorbidities including congenital heart disease, also linked to inadequate placentation. Coincidentally, T21 placental syncytiotrophoblasts that act as the primary barriers at the maternal-fetal interface fail to adequately fuse into multinucleated syncytial plaques, and the underlying etiology is unknown. We hypothesize that defects in T21 syncytiotrophoblast differentiation occur during peri-implantation development and contribute to a wide range of diseases in individuals with T21. The long-term goals of our research are to provide a mechanism by which syncytiotrophoblast differentiation is disrupted in T21 and provide opportunities for therapeutic intervention. In aim 1, we will identify transcriptional differences of T21 implantation-stage trophoblasts by differentiating six pairs of T21 and matching euploid induced pluripotent stem (IPS) cell lines into syncytiotrophoblast-like cells with treatment of BMP4, A83-01, and PD173074 (BAP) and performing RNA-sequencing. In aim 2, we will assess canonical estrogen-driven transcription in T21 and euploid BAP-treated IPS cells. We will knockdown the third copy of NRIP1, an estrogen receptor inhibitor on chromosome 21, with crispr/CAS9 technology in T21 BAP-treated IPS cells to determine the influence of estrogen receptor inhibition on T21 syncytiotrophoblast fusion. We will also overexpress a third copy of NRIP1 in euploid lines and measure estrogen mediated transcriptional activity and syncytiotrophoblast cell fusion. These results will help to confirm or deny the involvement of NRIP1 and canonical estrogen signaling in the T21 syncytiotrophoblast disease phenotype. In aim 3, we will differentiate T21 and euploid ipscs to cardiomyocytes and supplement them with conditioned medium from T21 and euploid trophoblast cultures to reveal a relationship between impaired T21 trophoblasts on cardiomyocyte development. In summary, our proposal uses cutting edge models and techniques that have not been used in T21 trophoblast research to demonstrate the significance of abnormal placentation on long-term health.