Effect of an anti-atherogenic mediator, sphingosine 1-phosphate on lipid Metabolism

我们假设脂蛋白中的1-磷酸鞘氨醇（S1 P）可能是脂质代谢的调节剂。本研究以肝细胞为研究对象，（1）筛选新的S1 P反应基因，（2）在肝细胞核因子（hepatocyte nuclear factor，HNF）4a、HNF 1a和小异二聚体伴侣（small heterodimer partner，SHP）基因上寻找S1 P反应区域。这三个基因被认为在脂质代谢中起重要作用，并被报道对S1 P起反应。（1）筛选S1 P反应的候选基因：利用DNA微阵列技术筛选S1 P抑制表达的基因。由于我们不能从小鼠中制备良好的原代培养肝细胞，因此我们使用来自HpG 2细胞的RNA样品进行DNA微阵列分析。然后，我们尝试使用真实的时间PCR技术（TaqMan系统）确认这些候选者的表达，然而，我们未能获得再现的结果。因此，我们接下来通过搜索已发表的论文来选择一些候选人。我们使用TaqMan系统检测了我们从搜索中获得的基因表达或候选基因。利用这种方法，我们发现了新的S1 P反应基因，即神经元源性孤儿受体-1（NOR-1）。我们还证实NOR-1是小鼠原代培养肝细胞中S1 P应答基因。（2）HNF 4a、HNF 1a和SHP基因分析--未发现这些基因对S1 P有反应。

We assumed that sphingosine 1-phosphate (S1P) in the lipoprotein could be a modifier of lipid metabolism. In this study, using hepatic cells, (1) we selected the new S1P responsive gene and (2) we also try to find a S1P responsive region on the gene of hepatocyte nuclear factor (HNF) 4a, HNF1a and small hetrodimer partner (SHP). These three genes are thought to play important roles on lipid metabolism and reported to respond to S1P.(1)Select a candidate gene responsive to S1P -Using DNA microarrey technique, we selected some genes of which expressions were decreased by S1P. At this time, we used RNA samples from HpG2 cells for the DNA microarrey analysis, since we can not prepare good primary cultured hepatocytes from mouse at this time. Then, we tried to confirm the expressions of these candidates using a real time PCR technique (TaqMan system), however, we failed to obtain the reproduced results. So we next selected some candidates by searching published papers. We examined the gene expressions or the candidates that we obtained from the searching, using TaqMan system. Using this approach, we found the new S1P responsive gene that is neuron-derived orphan receptor-1 (NOR-1). We also confirmed NOR-1 is the S1P responsive gene in mouse primary cultured hepatocytes.(2)HNF4a, HNF1a and SHP gene analysis-We could not obtain any results that these genes are responded to S1P as reported earlier.