in vivo promoter analysis of lipogenic genes

本研究以SREBP-1c基因启动子活性为研究对象，对脂肪生成的调控机制进行了深入的研究。然而，SREBP-1c启动子的调控机制仍不清楚，我们认为这是由于体外分析的局限性。在此我们建立了两个体内系统来评估SREBP-1c启动子活性：1. SREBP-1c启动子驱动的荧光素酶转基因小鼠和2.将腺病毒启动子-报告基因融合基因转移到肝脏中的等效小鼠。转基因小鼠模型：我们建立了一个转基因小鼠模型，该模型携带与荧光素酶报告基因融合的2.2kb启动子区。这些转基因小鼠在肝脏和脂肪组织中表现出与内源性SREBP-1c mRNA基本相同的报告基因再喂养反应。腺病毒转导模型与腺病毒介导的SREBP-1c-启动子-荧光素酶融合基因转导肝脏的实验结果一致，证明SREBP-1c基因表达的调控是在转录水平上进行的，且2.2kb的5 '侧翼区足以进行这种调控。特别是，后者的策略提供了一个可行的方法来确定启动子区域负责的再喂养反应的SREBP-1c表达。我们计划通过这些体内分析进一步研究脂肪生成基因调控的分子机制。

We have focused investigation of the regulation of lipogenesis on studying the promoter activity of SREBP-1c gene, a transcription factor deeply involved in the regulation of lipogenic genes in liver. However, the regulatory mechanisms of SREBP-1c promoter remain unclear, which we consider is due to the limitation of in vitro analysis. Here we established two in vivo systems to estimate the SREBP-1c promoter activity: 1. SREBP-1c promoter-driven luciferase trangenic mice and 2. equivalent mice with adenoviral promoter-reporter fusion gene transfer into liver.1. Transgenic mouse model : we generated a transgenic mouse model that carries 2.2kb promoter region fused to the luciferase reporter gene. These transgenic mice exhibited refeeding responses of the reporter in liver and adipose tissues with extents essentially identical to those of endogenous SREBP-1c mRNA.2. Adenoviral transduction model the same results were obtained from experiments using adenovirus-mediated SREBP-1c-promoter-luciferase fusion gene transduction to liver.These data demonstrate that the regulation of SREBP-1c gene expression is at the transcription level, and that the 2.2kb 5'-flanking region is sufficient for this regulation. Especially, the latter strategy provided a feasible approach to identify the promoter regions responsible for the refeeding response of SREBP-1c expression. We are planning to further investigate the molecular mechanism of lipogenic gene regulation through these in vivo analyses.