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疾病如高血压、冠心病、2型糖尿病和神经精神疾病有关。产前营养，通过婴儿出生时的大小和体重来评估，是最广泛检查的变量。动物研究表明，营养不良可能是其他不利环境事件的标志，如产前压力，导致新陈代谢的永久性变化。分子机制赋予细胞的永久记忆（不利的）产前环境影响仍然是未知的。我们假设DNA甲基化在CpG二核苷酸上符合所有要求，成为一个重要的贡献者：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。作为我们解决这一假设的初步方法，我们建议优化动物模型，以评估补充各种甲基供体如何影响发育和晚年疾病中的DNA甲基化。我们将首先使用现有技术筛选具有CpG甲基化变化的基因，但同时将开发一种“甲基化微阵列”，以进行更敏感和更快的评估。我们还将使用现有的cDNA微阵列测量基因表达，并建立分析技术，将CpG甲基化谱与基因表达谱相关联。在已发现的候选基因中，我们将优先考虑那些在神经功能中起作用的基因进行进一步的详细研究。最后，为了证明DNA甲基化可以与有害环境因素相互作用的原理，我们将在发育期间将甲基供体处理的小鼠暴露于低剂量丙戊酸并研究其长期影响。选择丙戊酸是因为它已被证明对神经元具有致畸作用，导致轴突分支缺陷，这是通过其作为组蛋白去乙酰化酶（HDAC）抑制剂的有效作用来实现的。甲基化依赖性转录抑制需要HDAC功能，因此DNA甲基化和VPA可以相互作用。这些实验将提供DNA甲基化在胎儿编程中的作用，并为该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.