A murine model for placental metabolic reprogramming

胎盘代谢重编程的小鼠模型

• 批准号: 8355935
• 负责人: Nicholas Illsley
• 金额: $ 9.27万
• 依托单位: HACKENSACK UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-20 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8355935
• 关键词: Altitude; Animals; Brain; Cell Respiration; Cells; Chronic; Code; Consumption; Coupled; Data; Development; Diagnostic tests; Embryo; Ensure; Fetal Growth; Fetal Growth Retardation; Fetus; Gap Junctions; Gene Expression; Generations; Glucose; Growth; HIF1A gene; Heart; Human; Hypoxia; In Vitro; Inner Cell Mass; Insulin; Investigation; Lentivirus Vector; Mediating; Metabolic; Metabolism; Methodology; MicroRNAs; Modeling; Morphology; Mus; Nutrient; Oxygen; Oxygen Consumption; Oxygen measurement, partial pressure, arterial; Pathology; Placenta; Pre-Eclampsia; Pregnancy; Process; Protocols documentation; Regulation; Relative (related person); Research; Role; Staging; Stress; System; Techniques; Testing; Time; Vascularization; anaerobic glycolysis; blastocyst; cost; fetal; fetus hypoxia; hypoxia inducible factor 1; in vivo; in vivo Model; knock-down; model development; mouse model; operation; particle; response; small hairpin RNA; tool; transcription factor; vector

DESCRIPTION (provided by applicant): Hypoxia contributes to reduced fetal growth in major pathological conditions such as intrauterine growth restriction (IUGR) and preeclampsia. Research thus far has failed to develop a means by which these severely compromised pregnancies can be detected early nor has it revealed the specific mechanisms by which hypoxia leads to fetal growth restriction. We have used a unique human model of chronic (altitude-induced) hypoxia to show that despite a substantial decrement in maternal arterial oxygen tension, hypoxia is not the proximate cause of the fetal growth restriction; oxygen delivery to the placenta and fetus is not reduced and fetal oxygen consumption is unaffected. Instead, it is fetal circulating glucose concentrations, fetal glucose consumption and fetal insuli levels that are significantly reduced. These in vivo findings point to excess placental glucose consumption, reducing transfer to the fetus, as an initiating step in fetal growth restriction. Metabolic reprogramming, also known as "oxygen sparing" appears to be the underlying cause, a phenomenon in which hypoxia actively and reversibly inhibits oxidative metabolism and oxygen consumption through alterations mediated by the Hypoxia-Inducible Factor-1 (HIF-1) transcription factor. Our in vivo data supports that metabolic reprogramming is crucial for ensuring fetal survival, but at the expense of growth. It occurs prior to the operation of the othe factors contributing to fetal growth restriction. Identification of the means by which hypoxia initiates reduction in fetal growth will permit development of diagnostic tests and ameliorative therapies for use, prior to irreversible fetal compromise. As a part of our continuing studies we wish to develop a murine model in which placental metabolic reprogramming mechanisms and the resultant effects on fetoplacental growth can be identified and tested in vivo. In this application we propose to develop a murine model for inducible, placenta-specific HIF-1 knockdown. We will target HIF-1 since it is the regulatory nexus for all metabolic reprogramming mechanisms described thus far. To restrict knockdown to the placenta, we will take advantage of a recently described technique for lentiviral transduction to deliver HIF-1¿shRNAmir to the outer cell layer of the blastocyst but not the inner cell mass, leading to placental transduction without effects on the fetus. To avoid the embryonic lethality which has complicated previous (systemic) HIF-1 knockdown studies, we will use an inducible vector, allowing us to inhibit placental HIF-1 hypoxic responses at physiologically relevant time points in pregnancy, once major structural development is complete. We will develop this model through the following aims: (1) developing the lentiviral tools for knock down of murine HIF-1 and (2) testing an in vivo model for placental knockdown of HIF-1 using lentiviral transduction of HIF-1 shRNAmir. Development of this model will have a significant impact on studies of fetal hypoxia and growth. PUBLIC HEALTH RELEVANCE: Reduced availability of oxygen contributes to reduced fetal growth in major problems such as intrauterine growth restriction and preeclampsia. Our results in the human however suggest that in condition of reduced oxygen, the placenta alters the mix of nutrients transferred to the fetus, maintaining fetal survival at the cost of reduced growth, an starting the process of fetal growth restriction. As a part of our continuing studies we propose to generate a mouse model in which we can modify the placental regulation of oxygen use at different points in pregnancy to investigate the effects of alteration in nutrient supply on fetal growth.

描述(由申请人提供)：在主要的病理情况下，如宫内生长受限(IUGR)和先兆子痫，低氧会导致胎儿生长减少。到目前为止，研究还没有开发出一种方法来早期发现这些严重受损的怀孕，也没有揭示缺氧导致胎儿生长受限的具体机制。我们使用了一种独特的人类慢性(海拔诱导)缺氧模型，以表明尽管母亲的动脉血氧分压显著降低，但缺氧并不是胎儿生长受限的直接原因；向胎盘和胎儿的氧气输送没有减少，胎儿的氧气消耗也没有受到影响。相反，显著降低的是胎儿循环葡萄糖浓度、胎儿葡萄糖消耗量和胎儿胰岛素水平。这些体内研究结果表明，胎盘葡萄糖消耗过多，减少了对胎儿的转运，是胎儿生长受限的起始步骤。代谢重编程，也被称为“节氧”似乎是潜在的原因，这是一种现象，在这种现象中，低氧通过缺氧诱导因子-1(HIF-1)转录因子介导的改变，积极地和可逆地抑制氧化代谢和氧气消耗。我们的体内数据支持代谢重新编程对于确保胎儿存活至关重要，但代价是生长。它发生在其他导致胎儿生长受限的因素手术之前.确定缺氧引起胎儿生长减慢的方法将使诊断测试和改善治疗方法的发展成为可能，以便在不可逆转的胎儿损害之前使用。作为我们继续研究的一部分，我们希望建立一种小鼠模型，在该模型中，胎盘代谢重编程机制和由此产生的对胎儿胎盘生长的影响可以在体内识别和测试。在这项应用中，我们建议建立一种可诱导的、胎盘特异性HIF-1基因敲除的小鼠模型。我们将以HIF-1为目标，因为它是迄今为止描述的所有代谢重新编程机制的调节纽带。为了将基因敲除限于胎盘，我们将利用最近描述的慢病毒转导技术将HIF-1？shRNAmir转导到胚泡的外层，而不是内细胞团，从而在不影响胎儿的情况下进行胎盘转导。为了避免先前复杂的(系统性)HIF-1基因敲除研究中的胚胎致死性，我们将使用可诱导的载体，使我们能够在怀孕期间的生理相关时间点抑制胎盘HIF-1的缺氧反应，一旦主要结构发育完成。我们将通过以下目标来发展这个模型：(1)开发慢病毒工具来击倒小鼠HIF-1和(2)在体内测试一个 慢病毒转导HIF-1 shRNAmir基因抑制胎盘HIF-1的模型该模型的建立将对胎儿缺氧和生长的研究产生重大影响。 与公共卫生相关：氧气供应减少会导致胎儿生长减少，主要问题包括胎儿宫内发育受限和先兆子痫。然而，我们在人体中的结果表明，在缺氧的条件下，胎盘改变了转移到胎儿的营养物质的组合，以减少生长为代价维持胎儿的存活，启动了胎儿生长受限的过程。作为我们继续学习的一部分，我们建议 建立一个小鼠模型，在这个模型中，我们可以修改胎盘对怀孕不同时期氧气使用的调节，以研究营养供应变化对胎儿生长的影响。