Multiple studies in humans and animal models demonstrate that obesity in pregnancy significantly increases the risk of developing obesity after birth. In previous studies in human and animal models, we and others have determined that obesity causes oxidative stress and mitochondrial dysfunction in white adipose tissue in pregnant females. Further, maternal obesity alters mitochondria function in pre-implantation embryos which is associated with abnormal mitochondria function in key metabolic tissues in the offspring. Finally, in previous studies in rodent models, treating the pregnant dam with antioxidants prevents the development of obesity in the offspring. These studies strongly suggest that maternal obesity alters mitochondria function in the offspring which is directly linked to the development of obesity and the metabolic syndrome later in life. The molecular mechanisms by which this process occurs is the focus of this proposal. Extracellular vesicles (EVs) contain mitochondria components such as mtDNA and protein, and possibly functional mitochondria which can be incorporated into the recipient cell mitochondria network resulting in changes in mitochondria function. Adipose tissue produces large numbers of EVs which induce inflammation, modulate glucose and lipid metabolism and recently have been shown to alter placenta function. We hypothesize that obesity during pregnancy increases the secretion of EVs from adipose tissue that contain abnormal mitochondrial cargo, and that these EVs traffic to the embryo, leading to abnormal mitochondria function which in turn reprograms the offspring to develop obesity later in life. In SA1 we will test the hypothesis that obesity in pregnancy alters the size distribution, numbers, and mitochondria cargo content of circulating adipocyte EVs. Using our established murine model of obesity in pregnancy, we will isolate and characterize circulating adipocyte EVs from plasma and adipose tissue of obese and lean pregnant dams. In SA2 we will test the hypothesis that maternal adipocyte EVs transfer mitochondria cargo to the embryo which alters the metabolic homeostasis of the embryo and offspring. In vitro experiments will assess the capability of circulating or in vitro obtained adipocyte EVs from early pregnant obese dams of transferring mitochondria cargo to preimplantation embryos. Using an in vivo approach, we will determine if circulating adipocyte EVs from obese pregnant dams transfer abnormal mitochondria cargo that is incorporated into mitochondria of embryos from lean pregnant dams. We will generate transgenic mice expressing a mitochondria GFP tag only in adipocytes (MITO-Tag:Adipoq-Cre). Finally, EVs will be isolated from obese MITO-Tag:Adipoq-Cre pregnant mice and injected into lean pregnant mice daily from e1-e4.5. E4.5. Embryos will be harvested and localization of donor EV mitochondria to the mitochondria network of the recipient embryo will be assessed by immunofluorescent microscopy. Mitochondria function of e4.5 recipient embryos will also be measured. Body composition, glucose tolerance, and localization of maternally derived mitochondria will be assessed in offspring in adulthood.
Maternal obesity leads to the development of obesity in the offspring. We hypothesize that adipose tissue from obese dams releases extracellular vesicles that contain mitochondria cargo. These EVs traffic to the developing embryo resulting in abnormal mitochondria function in the offspring leading to obesity in adulthood.
