Epigenetic programming of infant mesenchymal stem cells: mechanisms for obesity and diabetes risk in humans

项目摘要/摘要 肥胖母亲所生的孩子在晚年患肥胖症和糖尿病的风险更高， 独立于生活方式因素，如体力活动或营养。而一些肥胖母亲所生的孩子 不会继续发展成肥胖或胰岛素抵抗，对于那些会发展成肥胖或胰岛素抵抗的人来说，人们对母亲的情况知之甚少 暴露(例如，高胰岛素血症)可能会影响人类的儿童结局。我们用人类，婴儿 从出生时收集的脐带组织中培养的间充质干细胞(MSCs)，用于研究 人类肥胖和糖尿病风险的机制。人类和动物研究，以及我们自己的MSC数据， 表明母体、间充质干细胞和婴儿新陈代谢之间有很强的相关性。例如，出生婴儿的骨髓间充质干细胞 对于肥胖和正常体重的母亲来说，脂代谢和能量感应分子存在扰动 调节脂质代谢，如我们在表观遗传学中观察到的AMP激活的蛋白激酶(AMPK) 水平(DNA甲基化)。OB-MSCs在体外对代谢应激的反应也损害了AMPK的激活， 这可能会影响脂肪分配和燃料利用的变化，以响应代谢刺激。此外， MSC脂代谢与出生时测量的婴儿脂肪质量相关。这些观察使这成为一种 体外研究人类代谢表型表观遗传编程的新模型。我们的 独特的翻译方法使我们能够在基本的科学模型中保持人类的可变性。这样的整合 对临床样本的机械性研究将帮助我们实现我们理解的长期目标 人类新陈代谢在分子水平上的发育规划机制。这个项目 不仅将推动理解人类发育的分子基础的领域 编程，但也可以确定有助于后代表型支持的可修改的母体因素 实施急需的肥胖预防战略。因此，这个问题的中心假设是 建议是母体代谢的紊乱诱导婴儿的MSC表观遗传信号促进 细胞燃料转换的失调和线粒体功能障碍。该项目利用了我们独特的资源 已经从150名婴儿中收集的MSCs，作为特征良好的纵向产前队列(健康)的一部分 启动，R01DK076648)。因此，虽然目标1和2将决定改变的脂肪分配和机制 体重正常的婴儿和肥胖母亲的MSCs中的线粒体功能障碍，Aim 3将扩大 将这一知识用于人口科学，在更大的队列中验证了我们的初步数据。目标1将决定 母体肥胖诱导的表观遗传学特征对子代骨髓间充质干细胞燃料转换和脂质分配的影响 以应对营养供应的变化。目标2将确定表观遗传特征是否促进 Ob-MSCs与NW-MSCs的线粒体功能障碍和底物氧化减少。目标3将证实 用特异性试验确定母体代谢的脐带间充质干细胞模型的临床意义 预测MSC代谢的指标，反过来，预测婴儿结局的MSC代谢指标。

PROJECT SUMMARY/ABSTRACT Children born to mothers with obesity are at increased risk for developing obesity and diabetes later in life, independent of lifestyle factors, such as physical activity or nutrition. While some children born to obese mothers will not go on to develop obesity or insulin resistance, for those who do, little is known about how maternal exposures (e.g., hyperinsulinemia) may influence child outcomes in humans. We use human, infant mesenchymal stem cells (MSCs), cultured from umbilical cord tissue collected at birth, for investigating mechanisms of obesity and diabetes risk in humans. Human and animal studies, as well as our own MSC data, show strong association between maternal, MSC and infant metabolism. For example, MSCs from infants born to obese vs. normal weight mothers have perturbations in lipid metabolism and energy sensing molecules regulating lipid metabolism, such as AMP-activated protein kinase (AMPK), which we observed at the epigenetic level (DNA methylation). Ob-MSCs also have impaired AMPK activation in response to metabolic stress in vitro, which could compromise lipid partitioning and shifts in fuel utilization in response to metabolic stimuli. Moreover, MSC lipid metabolism correlates with fat mass of the infants measured at birth. These observations make this a novel model in which to investigate the epigenetic programming of human metabolic phenotypes in vitro. Our unique, translational approach allows us to maintain human variability in a basic science model. Such integration of mechanistic investigation with clinical samples will help us to achieve our long-term goal of understanding mechanisms for the developmental programming of metabolism at the molecular level in humans. This project will not only advance the field for understanding the molecular underpinnings of human developmental programming, but may also identify modifiable maternal factors contributing to offspring phenotype supporting implementation of critically needed obesity prevention strategies. Therefore, the central hypothesis for this proposal is that perturbations in maternal metabolism induce infant MSC epigenetic signatures promoting dysregulation of cellular fuel switching and mitochondrial dysfunction. This project leverages our unique resource of MSCs already collected from >150 infants as part of a well characterized, longitudinal pre-birth cohort (Healthy Start, R01DK076648). Thus, while Aims 1&2 will determine mechanisms for altered lipid partitioning and mitochondrial dysfunction in MSCs from infants born to normal weight versus obese mothers, Aim 3 will expand this knowledge to population science, validating our preliminary data in a larger cohort. Aim 1 will determine the impact of maternal obesity-induced epigenetic signatures on offspring MSC fuel switching and lipid partitioning in response to changes in nutrient supply. Aim 2 will determine whether epigenetic signature promotes mitochondrial dysfunction and reduced substrate oxidation in Ob- vs. NW-MSCs. Aim 3 will substantiate the clinical relevance of the umbilical cord MSC model using specific tests to determine maternal metabolic measures predictive of MSC metabolism and, in turn, MSC metabolic measures predictive of infant outcomes.