A Two-Pronged Approach to Preeclampsia: Understanding Gene Expression and Targeting sFlt1 using RNAi

Abstract

Preeclampsia (PE) is a disorder affecting 2-10% of pregnancies worldwide. Clinical signs include high blood pressure (HBP) and proteinuria in the mother after the 20th week of pregnancy. Currently, the only cure for PE is delivery of the fetus, which is often necessary preterm and thus dangerous for both mother and fetus. Maternal symptoms of PE are caused by excess anti-angiogenic proteins of placental origin called soluble Flt1s (sFlt1s). sFlt1 mRNA isoforms are produced by alternative polyadenylation (APA) of full-length Flt1 (fl-Flt1) pre- mRNA. While fl-Flt1 encodes a transmembrane protein, sFlt1s encode truncated proteins that are soluble. Multiple sFlt1 isoforms exist, and their respective contribution to the pathophysiology of PE is unclear. Furthermore, it is unknown whether there is a genome-wide role for APA in PE. In my thesis research, I developed a polyadenylation site sequencing method, and used this method to simultaneously quantify transcriptome-wide polyadenylation site usage and gene expression levels in normal, early-onset PE, and late-onset PE human placentae. I observed distinct expression profiles amongst the three groups, with differential expression of genes in several functional categories, including angiogenesis. I found that three sFlt1 isoforms account for >94% of all placental FLT1 transcripts, and that increased transcription of the entire FLT1 locus drives upregulation of both fl-Flt1 and sFlt1 in PE. I found that APA does not contribute substantially to PE pathophysiology. I also identified siRNAs that knock down sFlt1 mRNA efficiently in cell lines that pave the way for further development of novel RNAi based therapeutics to alleviate PE.