Identification of transcription factors that regulate placental sFLT1 expression

Increased soluble FMS-like tyrosine kinase 1 (sFLT1) levels have been associated with preeclampsia, chronic kidney diseases, and kidney transplant rejection. However, lower levels of sFLT1 exhibit beneficial properties in various processes, such as the organization of the actin cytoskeleton in podocytes and immune regulation in healthy pregnancy. Therefore, understanding the transcriptional regulation of sFLT-1 and preserving appropriate expression levels are critical for effective treatment of preeclampsia and other diseases. Cytotrophoblasts (CTBs) were isolated from three first-trimester placentas and differentiated into extravillous trophoblasts (EVTs) for 6 days. RNA was extracted at different time points and used for RNA sequencing. Differentially expressed genes (DEGs) and transcription factors (DETFs) were analyzed. Transcription factor (TF) enrichment analysis and pathway analysis were performed on DEGs screened from EVTs and CTBs. TF inhibitors were added to primary CTBs directly or during CTB to EVT differentiation to confirm the regulatory effect of TFs on sFLT1 expression. In total, 197 TFs were differentially expressed between CTBs and EVTs, among which 15 DETFs (EPAS1, ETS1, TBX3, CEBPB, FLI1, TEAD4, GATA4, TBX2, LMX1B, ARNT, FOXM1, ERF, PRDM1, TFAP2A, and NR2F2) that potentially regulate sFLT1 expression were predicted by ChEA3 and KnockTF software. The mRNA levels of 15 DETFs were validated upon CTBs differentiation into both EVTs and syncytiotrophoblasts. The regulatory effects of FOXM1 and CEBPB were confirmed in vitro experiments, and their expression patterns were validated during CTBs differentiation into EVTs and in first-trimester placentas. Pathway analysis showed that FLT1 was involved in P13K-Akt, Rap1, MAPK, Ras, and HIF-1 signaling pathways, focal adhesion, and cytokine-cytokine receptor interaction. Protein-protein interaction analysis showed that FLT4, PDGFB, TGFB1, IL6R, TNFRSF1B, CSF1R, and TGFB2 interact with FLT1. The identified TFs can serve as therapeutic targets in preeclampsia to keep the sFLT1 levels within appropriate limits.