基于代谢组学的叶酸缺乏影响胚胎脑发育机制研究

Folate deficiency is reported to be one of the main causes of Neural tube defects (NTDs). But the metabolic mechanism associated low folate intake with abnormal brain development is still ambiguous. Preliminary research found NTDs is related to one carbon metabolic disturbance. Metabonomics research showed basic material metabolic disturbance in NTDs case. In order to investigate the distribution of one carbon unit in one carbon mechanism and nucleotide mechanism after one carbon unit insufficiency under low level folate intake, and to analyze how mechanism disturbance harm embryo brain development, this program assume to present a metabonomics study to investigate Metabolic Patterns alterations in one carbon and basic material metabolism during folate deficiency or folate metabolism disorder or after folate supplementation on animal models and NTDs case. We assume to analyze the correlation of this metabolic changes with different embryo brain developments and to find the metabolic biomarker. To the cases with obvious difference in one carbon metabolites, analysis on methylation and monoamine neurotransmitter may give a reason to explain how one carbon mechanism disturbance induced embryo brain maldevelopment. This program assumes to illustrate from metabolic mechanism point and the result may provide a scientific evidence for new therapeutic method.

叶酸缺乏是神经管畸形的重要致病因素，目前低叶酸影响胎脑发育的代谢机制尚不清楚。课题组前期研究发现神经管畸形与一碳代谢紊乱相关，代谢组学研究显示神经管畸形病例中有基础物质代谢紊乱。为了研究低叶酸引起一碳基团不足后，一碳基团如何在一碳代谢和核苷酸合成代谢之间分配，以及与之相关的代谢紊乱在胎脑异常发育中的作用。本课题拟在叶酸缺乏小鼠模型、关键酶基因缺陷小鼠模型和人类神经管畸形病例中系统研究叶酸缺乏或叶酸代谢障碍及叶酸回补后引起的一碳代谢和基础物质代谢的代谢谱图改变，分析其与胎脑不同发育结局的相关性，并获得不同叶酸水平引起不同发育结局的代谢标识物，为低叶酸致胎脑发育不良指示风险。对于一碳代谢物存在明显差异表达的病例，分析其甲基化状态和单胺类神经递质水平改变是否是低叶酸引起一碳代谢紊乱进而影响胎脑发育的深层原因。旨在从代谢角度阐明叶酸缺乏致胎脑异常发育机理，为新的治疗手段开发提供干预靶点和科学依据。

我国是神经管畸形的高发国家，叶酸缺乏是神经管畸形已知致病因素之一，既往神经管畸形的代谢组学研究，均未在神经管畸形病例中发现与叶酸特异相关的生物标记物以及受叶酸缺乏扰动的代谢通路。本项目以不同叶酸浓度的人类神经管畸形胚胎脑组织为研究对象，联合运动靶向与非靶向代谢组学方法，分析了低叶酸情况下，胚胎脑组织内差异表达的代谢物与显著受到扰动的代谢通路。 在此基础上对受到扰动显著的代谢产物进行了靶向的定量分析。结果发现，在胎脑叶酸缺乏情况下，除一碳代谢与嘌呤合成代谢外，芳香族氨基酸代谢、花生四烯酸代谢与氧化磷酸化均表现出显著性差异，多个神经递质前体差异表达。一碳代谢中同型半胱氨酸与S-腺苷同型半胱氨酸显著增高，而色氨酸，组氨酸、甘氨酸、蛋氨酸显著降低。上述被扰动的代谢通路中，花生四烯酸代谢与芳香族氨基酸代谢与神经管畸形的关系为首次发现，为今后开发针对性的治疗措施和干预手段拓展了新思路，开辟了新方向。