Diet-induced obesity affects miRNA expression in plasma extracellular vesicles of pregnant mice

Obesity during pregnancy is linked to a high risk of offspring overweight, insulin resistance, type 2 diabetes, and cardiometabolic disease in later life. However, the underlying mechanisms by which maternal factors drive these long-lasting effects remain to be fully elucidated. In our study, we have demonstrated that in diet-induced-obesity (DIO) pregnant mice, maternal small extracellular vesicles (sEV) in circulating system have the ability to cross the placental barrier and reach the liver of fetal mice, exerting a sustained adverse impact on offspring insulin sensitivity. Further investigations have revealed that pathogenically increased miR-29a-3p in maternal sEV from DIO mice can be delivered into livers of fetal offspring. Elevated miR-29a-3p subsequently alter epigenetic state in fetal liver via targeting several key methyltransferases and demethylases, interrupting the DNA methylation landscape, including hypomethylation of PGC-1α. Such epigenetic remodeling abnormally promotes early hepatic gluconeogenesis at fetal stage that contribute to the adult metabolic disturbance in offspring. Taken together, our finding suggests that the transplacental delivery of maternal sEV could serve as a potential mechanism for prenatal programming of metabolic health in offspring.