Human NPC1L1 Expression is Positively Regulated by PPARα
Human NPC1L1 Expression is Positively Regulated by PPARα
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DOI：
10.1007/s11095-010-0294-4
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发表时间：
2011-02-01
影响因子：
3.7
通讯作者：
Suzuki, Hiroshi
中科院分区：
文献类型：
--
作者：
Iwayanagi, Yuki;Takada, Tappei;Suzuki, Hiroshi
尼曼-匹克C1样蛋白1（NPC 1 L1）是依折麦布的药理学靶点，负责肠细胞和肝细胞中的胆固醇吸收。在本研究中，过氧化物酶体增殖物激活受体α的参与，（PPAR α）及其辅因子，过氧化物酶体增殖物激活受体γ辅激活因子1 α分析了人NPC 1 L1基因转录调控中的PGC 1 α（PGC 1 α）的作用，并对人NPC 1 L1基因5 '侧翼区进行了报告基因分析和电泳迁移率变动分析（EMSA），检测了siPPAR α的作用。用人NPC 1 L1启动子构建体观察到介导的反式激活。使用缺失和突变启动子构建体的详细分析揭示了人NPC 1 L1基因上游（-846/-834）存在功能性PPAR α反应元件（PPRE），通过EMSA证实了PPAR α和RXR α的直接结合。此外，PPAR α特异性敲低导致人源性HepG 2细胞中NPC 1 L1 mRNA和蛋白质的内源性表达显著降低。此外，PGC 1 α共转染刺激了SREBP 2/HNF 4 α和PPAR α/RXR α介导的人NPC 1 L1启动子的激活。此外，PGC 1 α刺激SREBP 2/HNF 4 α和PPAR α/RXR α介导的人NPC 1 L1的反式激活。这些发现可能为葡萄糖、脂肪酸和胆固醇稳态的密切关系提供新的见解。
Niemann-Pick C1-like 1 (NPC1L1), a pharmacological target of ezetimibe, is responsible for cholesterol absorption in enterocytes and hepatocytes. In the present study, the involvement of peroxisome proliferator-activated receptor alpha (PPAR alpha) and its cofactor, PPAR gamma coactivator 1 alpha (PGC1 alpha) in the transcriptional regulation of human NPC1L1 was analyzed.Reporter gene assays and electrophoretic mobility shift assays (EMSAs) were performed with the 5'-flanking region of the human NPC1L1 gene and the effect of siPPAR alpha was examined.PPAR alpha-mediated transactivation was observed with human NPC1L1 promoter constructs. Detailed analyses using deletion- and mutated-promoter constructs revealed the presence of a functional PPAR alpha-response element (PPRE) upstream of the human NPC1L1 gene (-846/-834), a direct binding of PPAR alpha and RXR alpha to which was confirmed by EMSAs. Moreover, PPAR alpha-specific knockdown resulted in a significant decrease in the endogenous expression of NPC1L1 mRNA and protein in human-derived HepG2 cells. Furthermore, cotransfection of PGC1 alpha stimulated the SREBP2/HNF4 alpha- and PPAR alpha/RXR alpha-mediated activation of the human NPC1L1 promoter.We found that PPAR alpha positively regulates human NPC1L1 transcription via direct binding to a PPRE. Additionally, PGC1 alpha stimulates the SREBP2/HNF4 alpha- and PPAR alpha/RXR alpha-mediated transactivation of human NPC1L1. These findings may provide new insights into the close relationship of glucose, fatty acids and cholesterol homeostasis.