CROSS TALK BETWEEN THE SPHINGOLIPID AND FOLATE PATHWAYS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 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调节叶酸缺乏和细胞内叶酸代谢障碍中的作用。现代生物医学缺乏研究，无法研究叶酸和鞘脂途径之间的功能相互作用。有具体迹象表明，这两条途径在功能上是相连的。(1)它们都依赖于丝氨酸：作为进入叶酸库的主要碳基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和抗叶酸的实验表明，这两种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效应。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. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 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 the disturbance of intracellular folate metabolism. The modern biomedical science lacks the studies, which would investigate functional interactions between the folate and sphingolipid pathways. 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 pathway is suggested by experiments with fumonisine, an inhibitor of ceramide synthase, and 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 effect 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. To determine whether ceramide signaling is a component of cellular response to impaired folate metabolism.