Single nucleotide polymorphism (-468 gly to ala) at the promoter region of sterol regulatory element-binding protein-1c associates with genetic defect of fructose-induced hepatic lipogenesis
Single nucleotide polymorphism (-468 gly to ala) at the promoter region of sterol regulatory element-binding protein-1c associates with genetic defect of fructose-induced hepatic lipogenesis
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DOI：
10.1074/jbc.m309449200
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发表时间：
2004-07-09
影响因子：
4.8
通讯作者：
Kashiwagi, A
中科院分区：
文献类型：
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作者：
Nagata, R;Nishio, Y;Kashiwagi, A
为了评估高果糖饮食引起的代谢紊乱的遗传易感性，我们研究了10个近交系小鼠的代谢特征，发现根据对高果糖饮食的反应将它们分为CBA组和DBA组。高果糖饮食显着增强了 CBA/JN 中甾醇调节元件结合蛋白-1 (SREBP-1) 的肝脏 mRNA 表达，但在 DBA/2N 中则不然。暴露于果糖后，在原代肝细胞中观察到类似的结果。在DBA组中距SREBP-1c基因的推定起始点～468bp处的核苷酸序列是腺嘌呤，而在CBA组中是鸟嘌呤。在来自 CBA/JN 的肝细胞中，CBA-SREBP-1c 启动子的活性分别响应 30 mM 果糖或 10 nM 胰岛素而显着增加 2.4 倍和 2.2 倍，而 DBA-SREBP-1c 启动子的活性对胰岛素有反应，但对果糖没有反应。在 DBA/2N 的肝细胞中，两种类型的 SREBP-1c 启动子响应胰岛素的活性均减弱。此外，电泳迁移率变动分析显示，一种未鉴定的核蛋白与由CBA/JN的SREBP-1c启动子的-453至-480bp之间的区域制成的寡核苷酸结合，但不与来自DBA/2N的探针结合。因此，在 DBA/2N 中，果糖再喂食后 SREBP-1 mRNA 表达的降低似乎与两种独立的机制相关：1) 未知蛋白与 SREBP-1c 启动子 453 至 480 bp 之间区域的结合丧失；2) SREBP-1c 启动子活性的胰岛素刺激受损。
To evaluate the genetic susceptibility to metabolic disorders induced by high fructose diet, we investigated the metabolic characteristics in 10 strains of inbred mice and found that they were separated into CBA and DBA groups according to the response to high fructose diet. The hepatic mRNA expression of the sterol regulatory element-binding protein-1 (SREBP-1) in CBA/JN was remarkably enhanced by high fructose diet but not in DBA/2N. Similar results were observed in primary hepatocytes after exposure to fructose. The nucleotide sequence at - 468 bp from the putative starting point of the SREBP-1c gene was adenine in the DBA group while it was guanine in the CBA group. In hepatocytes from CBA/JN, the activity of CBA-SREBP-1c promoter was significantly increased by 2.4- and 2.2-fold, in response to 30 mM fructose or 10 nM insulin, respectively, whereas the activity of DBA-SREBP-1c promoter responded to insulin but not to fructose. In hepatocytes from DBA/2N, both types of SREBP-1c promoter activities in response to insulin were attenuated. Furthermore, electrophoretic mobility shift assay revealed an unidentified nuclear protein bound to the oligonucleotides made from the region between - 453 to - 480 bp of the SREBP-1c promoter of CBA/JN but not to the probe from DBA/2N. Thus, in DBA/2N, the reduced mRNA expression of SREBP-1 after fructose refeeding appeared to associate with two independent mechanisms, 1) loss of binding of unidentified proteins to the region between - 453 to - 480 bp of the SREBP-1c promoter and 2) impaired insulin stimulation of SREBP-1c promoter activity.