Employing biologics to probe GPCR signaling in maternal and fetal health

and Abstract G protein-coupled receptors (GPCRs) regulate many physiological processes during pregnancy. Oxytocin receptor (OXTR) signaling initiates labor and aberrant signaling through the angiotensin II type I receptor (AT1R) is associated with preeclampsia, a hypertensive disorder of pregnancy and leading cause of pregnancy-related deaths and premature births. GPCRs are therapeutic targets for complications arising during pregnancy and in assisted reproduction, but current small-molecule and peptide drugs exhibit off-target binding, require constant intravenous administration due to short half-lives in vivo, and in some cases are fetotoxic limiting their use. Differing pharmacokinetic and pharmacodynamic profiles and the enhanced specificity make antibodies attractive therapeutic molecules for targeting GPCRs during pregnancy, but the mechanisms antibodies use to modulate GPCR signaling is poorly understood. Previous studies with synthetic antibody fragments and endogenous pathogenic autoantibodies indicate that antibodies can regulate GPCR signaling in a way that does not mirror the action of prototypical small-molecule and peptide ligands. This proposal combines receptor pharmacology, structural biology, and antibody engineering to 1) characterize the mechanisms antibody fragments use to suppress AT1R signaling and demonstrate their ability to selectively target maternal AT1R to safely treat hypertension during pregnancy, 2) develop antibody selection strategies to mechanistically probe how synthetic antibody fragments stabilize distinct states of AT1R and OXTR to regulate the recruitment of signaling effectors and direct biological responses, 3) investigate the mechanisms by which pathogenic autoantibodies dysregulate AT1R signaling in preeclampsia. Collectively, the proposed research will determine how antibodies can be leveraged as tools to dissect the finer details of GPCR signaling, provide insight into the complex pathophysiology of preeclampsia, and identify new avenues to therapeutically target GPCRs to treat preeclampsia, regulate labor, and improve outcomes in assisted reproduction. The aims described in this proposal will offer the PI ample opportunities to expand her scientific skillset in structural pharmacology and antibody engineering, gain training in reproductive biology, and strengthen her expertise in GPCR biology. Mentorship from Dr. Andrew Kruse, advisory committee members, and collaborators will provide the PI with the skills needed to complete the proposed work and transition to independence. The extensive training plan for both scientific and professional development, combined with strong institutional support, will aid the PI in establishing an interdisciplinary research program studying the molecular function of pregnancy-related GPCRs. Project Number: 4R00HD110612-03 | Fiscal Year: 2025 | NIH Institute/Center: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) | Principal Investigator: Meredith Skiba | Institution: UNIVERSITY OF MICHIGAN AT ANN ARBOR, ANN ARBOR, MI | Award Amount: $760,950 | Activity Code: R00 | Study Section: NSS View on NIH RePORTER: https://reporter.nih.gov/project-details/4R00HD11061203