P15 Redox regulation of splicing of the angiogenic factor soluble FLT-1 in a murine gestational hypertension model

Background Preeclampsia is a severe pregnancy complication which has long-term consequences on mother and child. Elevation of the soluble isoform of the anti-angiogenic factor sFlt1 in the maternal circulation is pivotal in the development of gestational hypertension, and kidney and placental dysfunction. Hallmarks of preeclampsia include oxidative stress, endothelial dysfunction. S-glutathionylation, a post-translational oxidative modification (oxPTM) reversed by glutaredoxin (Glrx), is emerging as an important regulator of angiogenic signaling in cardiovascular disease but has not been studied in PE. We aimed to identify the molecular basis for how redox imbalance may contribute to PE by disrupting placental angiogenesis. Methods We investigated the effects of oxPTM removal on placental angiogenic balance and PE phenotype, using Glrx overexpressing mice. In the setting of timed pregnancy we phenotyped the in vivo cardiovascular physiology, and combined with cellular in vitro studies using primary endothelial cells (EC). Exon-level micro-array and bioinformatics proteomic analysis identified a splicing factor as pivotal target in Glrx-mediated PE development. Results Mice overexpression Glrx (TG) developed hallmarks of PE with gestational hypertension, placental and kidney dysfunction. Interesting Glrx overexpression induced sFlt1 levels. Adenoviral Glrx overexpression functionally affected EC and trophoblasts and altered placental angiogenic balance. Of significance, Glrx elevated the placenta-specific sFlt1-e15a splice variant in EC and a genome-wide exon-level profiling revealed a global alteration of alternative splicing events in TG vs WT mice placenta. Bioinformatic analysis identified redox-sensitive targets directly relevant to splicing and PE. Further studies revealed redox sensitive thiols on the spliceosome machinery which disrupted EC angiogenesis and modulated among others Flt1 splicing. Conclusion Glrx-dependent removal appears to act as a redox switch regulates angiogenic pathways in the placenta via the modulation of redox-sensitive targets in the spliceosome machinery. Disruption of these sensitive may promote the vascular defects associated with PE phenotype. This work was funded by; Horizon 2020 Marie Skłodowska-Curie (765274, iPLACENTA); EU Framework 7, (626633, IVSCP); and Tenovus Scotland, T18–23.