Do Diet and DNA Methylation Affect Fetal Programming?

描述(由申请人提供)：可靠的流行病学数据支持，不利的宫内环境与成人发病的疾病有关，如高血压、冠心病、2型糖尿病和神经精神疾病。根据婴儿出生时的大小和体重评估的产前营养是被最广泛检查的变量。动物研究表明，营养不良可能是其他不利环境事件的标志，例如产前应激，这些事件会导致新陈代谢的永久性变化。在(不利的)产前环境影响下，赋予细胞永久记忆的分子机制仍不清楚。我们假设CpG二核苷酸的DNA甲基化符合所有条件，是一个重要的贡献者：它可以直接影响基因的表达谱，它是有丝分裂遗传的，它可以受到环境的影响。作为解决这一假设的最初方法，我们建议优化动物模型，以评估补充不同甲基供体如何影响发育过程中的DNA甲基化和以后生活中的疾病。我们最初将使用现有技术来筛选具有CpG甲基化变化的基因，但同时将开发一种更灵敏、更快评估的“甲基化微阵列”。我们还将利用现有的基因芯片测量基因表达，并建立分析技术，将CpG甲基化图谱与基因表达图谱相关联。在这样发现的候选基因中，我们将优先考虑那些与神经功能有关的基因，以进行进一步的详细研究。最后，为了证明DNA甲基化可以与有害的环境因素相互作用的原理，我们将在发育过程中将甲基供体处理的小鼠暴露于低剂量的丙戊酸中，并研究其长期影响。之所以选择丙戊酸，是因为已经证明，丙戊酸对神经元的致畸作用，导致轴突分支缺陷，是通过其作为组蛋白脱乙酰酶(HDAC)抑制剂的强大作用来实现的。依赖甲基化的转录抑制需要HDAC功能，DNA甲基化和VPA因此可以相互作用。这些实验应该可以深入了解DNA甲基化在胎儿编程中的作用，并为这一领域的未来研究开辟许多途径。

DESCRIPTION (provided by applicant): Solid epidemiologic data support that an unfavorable intrauterine environment is associated with adult-onset disorders such as hypertension, coronary heart disease, type 2 diabetes and neuropsychiatric disease. Prenatal nutrition, as assessed by infant size and weight at birth, is the most widely examined variable. Animal studies suggest that poor nutrition might be a marker for other adverse environmental events, such as prenatal stress, that result in permanent changes in metabolism. The molecular mechanism that confers a permanent memory on cells of (adverse) prenatal environmental influences is still unknown. We hypothesize that DNA methylation at CpG dinucleotides fits all requirements to be an important contributor: it can directly affect the expression profile of genes, it is mitotically inheritable and it can be influenced by the environment. As our initial approach to address this hypothesis we propose to optimize animal models to evaluate how supplementation with various methyl donors affects DNA methylation in development and disease in later life. We will initially use existing technologies to screen for genes with CpG methylation changes, but concurrently will develop a "methylation microarray" for a more sensitive and faster evaluation. We will also measure gene expression using existing cDNA microarrays and establish analysis techniques to correlate CpG methylation profiles with gene expression profiles. Of the candidate genes thus discovered, we will prioritize for further detailed investigation those with a role in neurological function. Finally, to prove the principle that DNA methylation can interact with noxious environmental factors, we will expose mice treated with the methyl donors to low doses of valproic acid in development and study the long-term effects. Valproic acid was chosen because it has been demonstrated that its teratogenic effect on neurons, resulting in axon branching defects, is by means of its potent action as a histone deacetylase (HDAC) inhibitor. HDAC function is required for methylation-dependent transcriptional repression and DNA methylation and VPA could thus interact. These experiments should provide insight into the role of DNA methylation in fetal programming and open many avenues for future studies in this area.