Effect of hypoxia on glucose metabolism in IUGR fetal liver

描述（由申请人提供）：在胎盘功能不全（PI-IUGR）引起的宫内生长受限妊娠中，胎儿肝脏对缺氧和胎盘到胎儿的营养转移减少产生代谢适应。这些适应包括糖异生的早期激活和对胰岛素抑制肝脏葡萄糖产生的抵抗。这一点很重要，因为虽然这些代谢适应可能是确保胎儿存活所必需的，但它们也可能导致生命后期的病理状况，包括型糖尿病（T2DM）。重要的是，PI-IUGR胎儿肝脏中这些代谢重编程适应的早期机制在很大程度上是未知的。我们的工作假设是，胎盘功能不全引起的缺氧通过HIF和FOXO1机制诱导代谢重编程，通过糖酵解增加和葡萄糖氧化减少来定义，这也导致PI-IUGR胎儿肝脏中胰岛素抑制葡萄糖产生的受损。本研究的目的是通过HIF-FOXO1通路确定缺氧对胎羊肝细胞代谢重编程和胰岛素抵抗发展的影响。为了验证这一途径，将从正常和PI-IUGR胎羊中分离出的肝细胞暴露在常氧和缺氧条件下。我们将检测糖异生、糖酵解和葡萄糖氧化等HIF和FOXO1靶基因的表达，以评估缺氧对诱导代谢重编程的影响。将测量使用胰岛素和不使用胰岛素时的葡萄糖生成率，以评估胰岛素敏感性。FOXO1的激活和定位将被测量，以确定缺氧和胰岛素敏感性的影响。基因沉默将用于测试fox01的作用。总的来说，这些结果将证明HIF和FOXO1之间是否存在一种新机制，有助于PI-IUGR期间慢性缺氧引起的胎儿肝脏糖代谢和胰岛素抵抗的变化。这些结果将具有重大的科学和潜在的临床影响，因为IUGR影响高达6-10%的妊娠，但仍不清楚IUGR后代在以后的生活中如何增加代谢性疾病的风险。早期暴露于缺氧之间的联系

DESCRIPTION (provided by applicant): The fetal liver in intrauterine growth restricted pregnancies caused by placental insufficiency (PI-IUGR) develops metabolic adaptations to hypoxia and decreased placenta-to-fetus nutrient transfer. These adaptations include an early activation of gluconeogenesis and resistance to insulin's suppression of hepatic glucose production. This is important because while these metabolic adaptations may be necessary to ensure fetal survival, they also can lead to pathological conditions later in life, including type diabetes (T2DM). Importantly, the early mechanisms responsible for these metabolic reprogramming adaptations in the PI-IUGR fetal liver are largely unknown. Our working hypothesis is that hypoxia from placental insufficiency induces metabolic reprogramming, defined by increased glycolysis and decreased glucose oxidation, via a HIF and FOXO1 mechanism that also results in impaired insulin suppression of glucose production in the PI-IUGR fetal liver. The goal of this proposal is to determine the effect of hypoxia via a HIF-FOXO1 pathway that produces metabolic reprogramming and development of insulin resistance in fetal sheep hepatocytes. To test this proposed pathway, isolated hepatocytes from normal and PI-IUGR fetal sheep will be exposed to normoxic and hypoxic conditions. The expression of genes in gluconeogenesis, glycolysis, and glucose oxidation and other HIF and FOXO1 target genes will be measured to assess the effect of hypoxia on the induction of metabolic reprogramming. Glucose production rates with and without insulin will be measured to assess insulin sensitivity. FOXO1 activation and localization will be measured to determine the effect of hypoxia and insulin sensitivity. Gene silencing will be used to test the role of FOXO1. Overall, these results will demonstrate whether a novel mechanism between HIF and FOXO1 contributes to changes in fetal hepatic glucose metabolism and insulin resistance resulting from chronic hypoxia during PI-IUGR. These results will have significant scientific and potential clinical impact because IUGR affects up to 6-10% of pregnancies, yet it remains unclear how IUGR offspring develop increased risk for metabolic disease in later life. A link between early exposure to hypoxia, along with other nutrient deficiencies, during PI-IUGR and increased hepatocellular nuclear FOXO1 activity during fetal life may hold the key to understanding how PI-IUGR promotes the development of hepatic insulin resistance and dysregulated hepatic glucose production, which underlie later life development of T2DM. Overall, these new R03 studies combined with our K01 results will provide a detailed framework describing the coordinated changes in hepatic metabolism that develop in utero during PI- IUGR and predispose the liver to metabolic problems after birth.