IDENTIFICATION OF AN ACTIVATOR HORMONE FOR A HEPATIC ORPHAN NUCLEAR RECEPTOR

FXR此前被认为是一种核受体，由 具有法尼基骨架的分子。我们正在继续进行这方面的工作 项目的特点是控制生理活动 通过分离法尼醇调节的基因，法尼醇类化合物和FXR。已解除关联 将小鼠肝细胞接种于培养皿中，分别与 50um法尼醇在0.5%的甲醇中或仅与甲醇一起使用3、8或17 几个小时。从处理过的细胞中分离出RNA并用于编程 综合。每个样本的cDNA被用 聚合酶链式反应和特异性寡核苷酸引物组。 鉴定了三个不同的法尼醇调节基因片段 一百多套底漆组合。这些基因片段是 目前正在接受DNA测序。作为这方面的第二个方面 项目，与FXR DNA结合的后半部分相对应的外显子 结构域是从小鼠基因组DNA文库中分离出来的。此FXR编码 外显子被磷酸甘油酸激酶打断 启动子驱动的新霉素基因元件。疱疹病毒胸苷激酶 基因被引入到一对1.8kb碱基的FXR基因组的下游 片段以创建用于选择的靶向载体 FXR破坏了胚胎干细胞。囊胚将被注射 这些细胞创造出具有FXR争议基因的动物。

FXR was previously identified as a nuclear receptor activated by molecules possessing farnesyl backbones. We have continued work on this project to characterize the physiological activities controlled by farnesoids and FXR by isolating farnesol-regulated genes. Dissociated mouse liver cells were seeded in culture dishes and incubated either with 50 uM farnesol in 0.5% methanol or with methanol alone for 3, 8, or 17 hours. RNAs were isolated from treated cells and used to program cDNA synthesis. The cDNAs from each sample were amplified using the polymerase chain reaction and specific oligonucleotide primer sets. Three distinct farnesol-regulated gene fragments were identified from more than one hundred primer set combinations. The gene fragments are presently being subjected to DNA sequencing. As a second aspect of this project, an exon corresponding to the second half of the FXR DNA-binding domain was isolated from a mouse genomic DNA library. This FXR-encoding exon was disrupted by substituting a phosphoglycerate kinase promoter-driven neomycin gene element. The herpes virus thymidine kinase gene was introduced downstream of a 1.8 kilobase pair FXR genomic fragment to create a targeting vector to be used for selecting FXR-disrupted embryonal stem cells. Blastocysts will be injected with these cells to create animals with FXR-disputed genes.