microRNA-Mediated Effects of Caloric Restriction on Trophoblast Invasion and Angiogenic Signaling in a Mouse Model of Fetal Growth Restriction

Trophoblast invasion is essential for normal placentation, with failure resulting in a fetal growth restriction (FGR) phenotype. Utilizing a calorie-restricted mouse model, we report progressive epigenetic, molecular, and phenotypic placental changes throughout gestation. Following maternal caloric restriction initiated at E9, we observed a significant reduction in fetal and placental weights beginning at E12.5, with persistent growth restriction at E14.5, E16.5, and E17.5. Immunohistochemistry of the decidual invasion site at E17.5 demonstrated reduced 1) decidual depth, 2) trophoblast invasion distance, and 3) trophoblast quantity within the decidua. Preceding these phenotypic changes, RT-qPCR revealed downregulation of trophoblast invasion and angiogenesis genes, including MMP2, MMP9, EFNA1, Rac1, Rras, ASCL2, TRAP2C, Prl7b1, VEGFa, VEGFb, PDGF, and AKT3, beginning as early as E14.5. Notably, microRNA sequencing at E12.5, prior to these transcriptional changes, identified significant upregulation of miR-503-5p, a predicted inhibitor of several of these pathways. The summation of these observations suggests miR-503-5p may be an early driver of placental dysfunction in FGR, linking maternal malnutrition to impaired trophoblast invasion and angiogenesis. These findings provide insight into the molecular mechanisms underlying placental insufficiency and highlight miR-503-5p as a potential therapeutic target for improving pregnancy outcomes in FGR.