A potential role for PLAGL1 in the regulation of blood vessel development

Throughout pregnancy, the placenta is important for the well-being of the fetus, transporting nutrients and waste between the maternal and fetal blood supply, secreting hormones, and serving as a protective barrier. To obtain a more complete understanding of placental development, we must understand how placental gene expression is regulated. We used RNA-seq data and ChIP-seq data for the enhancer associated mark, H3k27Ac, to study gene regulation in the mouse placenta at embryonic day (e) 9.5, when the placenta is developing a complex network of blood vessels which facilitate maternal-fetal exchange of material. We identified several transcription factors upregulated at e9.5 with enriched binding sites in e9.5-specific enhancers. We performed follow up studies to investigate the role of the most enriched transcription factor, PLAGL1, in placental development. The PLAGL1 binding motif was found in 233 regions which were significantly associated with genes involved in vasculature development. To further understand the role of PLAGL1, we performed an siRNA knockdown in a human placental cell line and analyzed the genes that significantly changed in expression compared to cells treated with a negative control siRNA. Genes that significantly decreased in expression along with PLAGL1 were associated with placental vasculature development terms. Using a tube assay, we found that decreased PLAGL1 expression lead to reduced tube formation. By identifying PLAGL1 as an important regulator in the placenta, our analysis improves our understanding of gene regulation in the placenta, an important step towards developing methods to diagnose and treat placental diseases. Examine changes in gene expression upon PLAGL1 knockdown. We performed RNA-seq in the human placental cell line, HTR-8/Svneo, with PLAGL1 siRNA and a negative control siRNA. We identified 4,003 differentially expressed genes, of which 1,964 were upregulated in the knockdown and 2,039 were downregulated in the knockdown. Genes downregulated along with PLAGL1 were associated with placenta vasculture development.