Insulin-stimulated adiponectin secretion in pregnancy is mediated by inhibition of adiponectin ubiquitination and degradation and is impaired in obesity

In pregnancy, adiponectin serves as an endocrine link between maternal adipose tissue, placental function and fetal growth, with low adiponectin promoting placental function and fetal growth. Circulating adiponectin levels are decreased in obese pregnant women and in gestational diabetes, which is believed to contribute to the insulin resistance and increased risk of fetal overgrowth associated with these conditions. However, the molecular mechanisms governing adiponectin secretion from maternal adipose tissues in pregnancy are poorly understood. Using visceral adipose tissue from lean and obese pregnant mice, we show that obesity in pregnancy is associated with adipose tissue inflammation, ER stress, insulin resistance, increased adiponectin ubiquitination and decreased total abundance of adiponectin. Moreover, adiponectin ubiquitination was increased in visceral fat of obese pregnant women as compared to lean pregnant women. We further observed that insulin prevents, whereas ER stress and inflammation promote, adiponectin ubiquitination and degradation in differentiated 3T3-L1 adipocytes. We have identified key molecular pathways regulating adiponectin secretion in pregnancy. This information will help us better understand the mechanisms controlling maternal insulin resistance and fetal growth in pregnancy and may provide a foundation for the development of strategies aimed at improving adiponectin production in pregnant women with obesity or gestational diabetes.