Physiological Ramifications of Chorionic Somatomammotropin Deficiency

项目总结 胎盘发育和功能受损是宫内生长受限(IUGR)的潜在病因。 这是婴儿死亡和发病的一个重要原因，使这些人容易患上成年人的代谢。 疾病，包括2型糖尿病。不幸的是，人类的进步还有很多方面 不了解的怀孕，特别是关于怀孕的原因和进展 并发胎盘发育受损。其中许多问题不能直接在 人类，预测需要相关的动物模型。确定原因是我们的长期目标 胎盘功能受损的背后，以及这一点在IUGR中的表现。为此，我们在活体内开发了 慢病毒介导的RNA干扰方法，以评估由 绵羊胎盘，一种动物模型，可用于研究稳定状态下的胎盘和胎儿生理学 非麻醉/非应激状态。绒毛膜生长抑素(CSH)被发现50周年 是胎盘分泌的最丰富的蛋白质之一，但目前还没有直接证据 定义了它的功能。慢病毒介导的RNA干扰引起的绵羊CSH缺陷妊娠 近期表现出明显的胎盘和胎儿生长受限，胎儿生长受限在 妊娠的前三分之一结束。在我们的CSH缺陷妊娠中，近期胎儿是 低胰岛素血症和低IGF1。胎盘营养转运蛋白，特别是SLC2A1(GLUT1)的表达 在怀孕早期减少，SLC2A1和SLC2A3(GLUT3)在短期内都显著降低， 提示CSH缺乏导致的IUGR可能至少部分是由于 胎盘营养物质的转移。在这里，我们将解决我们的核心假设，即CSH具有双重机制 在调节胎儿生长中的作用：1)它刺激胎盘发育和营养物质向胎儿的运输；2) 它还直接刺激妊娠早、中期和循环中胎儿组织旁分泌IGF1和IG2的表达 (内分泌)IGF1与妊娠晚期胰岛素的产生。这一假设得到了我们令人信服的 初步数据和研究CSH缺陷在非稳态下的影响的能力 麻醉/非应激状态。我们提出了三个具体目标。在目标1中，我们将检验假设 CSH缺陷妊娠早期和中期观察到的IUGR是胎盘受损的结果 葡萄糖转移到胎儿，并损害对胎儿组织IGF1和2表达的刺激。在《目标2》中我们将 检验CSH缺乏所观察到的妊娠晚期IUGR是胎盘受损的假说 葡萄糖转移到胎儿体内，降低胎儿循环中的胰岛素和IGF1浓度。在目标3中，我们将测试 妊娠晚期CSH缺乏导致体外和/或体内肝细胞和胰岛受损的假说 胰岛素样生长因子1和胰岛素的分泌。这些创新和强有力的研究相结合将 显著影响我们对体内胎盘-胎儿相互作用导致IUGR的理解。

PROJECT SUMMARY Impaired placental development and function is an underlying etiology of intrauterine growth restriction (IUGR), which is a significant cause of infant mortality and morbidity, predisposing these individuals to adult metabolic disease, including Type 2 Diabetes. Unfortunately, there are still many aspects of the progression of human pregnancy that are not understood, especially in regards to the causation and progression of pregnancies complicated by impaired placental development. Many of these questions cannot be directly addressed in humans, predicating the need for relevant animal models. It is our long-term goal to determine the causes behind impaired placental function, and how this manifests itself in IUGR. To this end, we developed in vivo lentiviral-mediated RNA interference methodologies in order to assess the function of genes expressed by the placenta in sheep, an animal model that allows the study of placental and fetal physiology under steady state non-anesthetized/non-stressed conditions. Chorionic Somatomammotropin (CSH) was discovered >50 year ago, and is one of the most abundant proteins secreted by the placenta, yet there is no direct evidence defining its function. CSH-deficient pregnancies, generated by lentiviral-mediated RNA interference in sheep exhibit significant placental and fetal growth restriction near-term, and the fetal growth restriction is apparent at the end of the first one-third of pregnancy. The near-term fetuses in our CSH-deficient pregnancies are hypoinsulinemic and hypo-IGF1. Placental expression of nutrient transporters, especially SLC2A1 (GLUT1) is diminished early in pregnancy, and both SLC2A1 and SLC2A3 (GLUT3) are significantly depressed near-term, suggesting that the IUGR resulting from CSH deficiency may be a consequence, at least in part, from impaired placental nutrient transfer. Herein, we will address our central hypothesis that CSH has a dual mechanistic role in regulating fetal growth: 1) it stimulates placental development and nutrient transport to the fetus, and 2) it also directly stimulates fetal tissue paracrine IGF1 and 2 expression in early to mid-gestation and circulating (endocrine) IGF1 and insulin production in late-gestation. This hypothesis is supported by our compelling preliminary data and the ability to study the ramifications of CSH deficiency under steady state non- anesthetized/non-stressed conditions. We propose three Specific Aims. In Aim 1 we will test the hypothesis that early- and mid-gestation IUGR observed in CSH-deficient pregnancies results from impaired placental glucose transfer to the fetus and impaired stimulation of fetal tissue IGF1 and 2 expression. In Aim 2 we will test the hypothesis that late-gestation IUGR observed with CSH deficiency results from impaired placental glucose transfer to the fetus and lower fetal circulating insulin and IGF1 concentrations. In Aim 3 we will test the hypothesis that late-gestation CSH deficiency causes impaired in vitro and/or in vivo hepatocyte and islet secretion of IGF1 and insulin, respectively. The combination of these innovative and robust studies will significantly impact on our understanding of in vivo placental-fetal interactions that result in IUGR.