CROSS TALK BETWEEN THE SPHINGOLIPID AND FOLATE PATHWAYS

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 该项目的主要目标是建立叶酸和鞘脂途径之间的功能联系，并探索潜在的分子机制。具体地说，我们建议评估鞘脂信号在叶酸缺乏的影响和对细胞内叶酸代谢紊乱的反应中的作用。目前，对叶酸和鞘脂途径之间的功能相互作用缺乏了解，但有特定的迹象表明，这两条途径在功能上是相连的。(1)它们都依赖丝氨酸：作为叶酸库的主要一碳基团供体和新的神经鞘糖脂生物合成的底物；(2)鞘磷脂途径依赖甲基化，直接(磷脂酰乙醇胺甲基化为磷脂酰胆碱)和间接(通过DNA/组蛋白甲基化调节酶表达)，而叶酸对于细胞甲基化至关重要；(3)神经酰胺合成酶抑制剂伏马辛的实验以及抗叶酸的实验表明这两条途径之间存在相互作用；(4)我们的研究表明，随着细胞内叶酸代谢的改变，神经酰胺水平发生了显著变化。因此，我们假设鞘磷脂通路的激活是叶酸应激的下游事件。鞘磷脂通路中甲基化的改变被认为是这一过程的潜在机制。目的验证假设：目的1.确定叶酸缺乏对鞘磷脂通路的影响。目的2.探讨叶酸依赖的甲基化在鞘脂通路中的作用。目的3.确定神经酰胺信号是否是叶酸代谢受损的细胞反应的一个组成部分。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The main objective of this project is to establish the functional connection between folate and sphingolipid pathways and to explore underlying molecular mechanisms. Specifically, we propose to evaluate the role of sphingolipid signaling in mediation of the effects of folate deficiency and responses to the disturbance of intracellular folate metabolism. At present, there is a lack of knowledge regarding functional interactions between the folate and sphingolipid pathways, but there are specific indications that the two pathways are functionally connected. (1) They both rely on serine: as the principal one-carbon group donor into the folate pool and a substrate for de novo sphingolipid biosynthesis; (2) sphingolipid pathways depend on methylation, directly (methylation of phosphatidylethanolamine to phosphatidylcholine) and indirectly (regulation of enzyme expression via DNA/histones methylation), while folates are crucial for cellular methylation; (3) cross talk between the two pathways is suggested by experiments with fumonisine, an inhibitor of ceramide synthase, as well as in experiments with antifolates; (4) our studies have demonstrated significant changes in the levels of ceramides upon alterations of intracellular folate metabolism. Therefore, we have hypothesized that activation of sphingolipid pathways is the down-stream event of the folate stress. The alteration of methylation in sphingolipid pathways is proposed as the underlying mechanism in this process. Aims to test the hypotheses are: Aim 1. Determine effects of folate deficiency on sphingolipid pathways. Aim 2. Explore the role of folate-dependent methylation in sphingolipid pathways. Aim 3. Determine whether ceramide signaling is a component of cellular response to impaired folate metabolism.