title: The SRE Motif in the Human PNPLA3 Promoter (-97 to -88 bp) Mediates Transactivational Effects of SREBP-1c.
abstract: Patatin-like phospholipase domain containing 3 (PNPLA3) is a non-secreted protein primarily expressed in liver and adipose tissue. Recently, numerous genetic studies have shown that PNPLA3 is a major susceptibility gene for nonalcoholic fatty liver disease (NAFLD). However, the mechanism involved in transcriptional regulation of the PNPLA3 gene remains unknown. We performed a detailed analysis of the human PNPLA3 gene promoter and identified two novel cis-acting elements (SRE and NFY binding motifs) located at -97/-88 and -26/-22 bp, respectively. Overexpression of SREBP-1c in HepG2 cells significantly increased PNPLA3 promoter activity. Mutation of either of the putative SRE or NFY binding motifs blocked the transactivation effects of SREBP-1c on the promoter. Overexpression of SREBP-1c and NFY together increased PNPLA3 promoter activity twice as much as that of SREBP-1c or NFY expression alone. This result suggests that SREBP-1c and NFY synergistically transactivate the human PNPLA3 gene. The ability of SREBP-1c and NFY to bind these cis-elements was confirmed using gel shift analysis. Putative SRE and NFY motifs also mediated synergistic insulin-induced transactivation of the PNPLA3 promoter in HepG2 cells. Additionally, the ability of SREBP-1c to bind to the PNPLA3 promoter was increased by insulin in a dose-dependent manner. Moreover, the treatment of HepG2 cells with the PI3K inhibitor LY294002 led to reduced insulin promoter-activating ability accompanied by a decrease in PNPLA3 and SREBP-1c protein expression. These results demonstrate that SREBP-1c is a direct activator of the human PNPLA3 gene and insulin transactivates the PNPLA3 gene via the PI3K-SREBP-1c/NFY pathway in HepG2 cells.
authors: Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China.
authors: Hua
authors: H
authors: Liang
authors: Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China.
authors: Jing
authors: J
authors: Xu
authors: Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China.
authors: Fen
authors: F
authors: Xu
authors: Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China.
authors: Hongxia
authors: H
authors: Liu
authors: Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China.
authors: Ding
authors: D
authors: Yuan
authors: Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China.
authors: Shuhua
authors: S
authors: Yuan
authors: Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China.
authors: Mengyin
authors: M
authors: Cai
authors: Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China.
authors: Jinhua
authors: J
authors: Yan
authors: Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, P.R.China.
authors: Jianping
authors: J
authors: Weng
mesh_terms: D023081:CCAAT-Binding Factor / Q000096:biosynthesis; D005786:Gene Expression Regulation / Q000235:genetics; D056945:Hep G2 Cells; D006801:Humans; D007328:Insulin / Q000378:metabolism; D008049:Lipase / Q000096:biosynthesis / Q000235:genetics*; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D009154:Mutation; D065626:Non-alcoholic Fatty Liver Disease / Q000235:genetics* / Q000473:pathology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051780:Sterol Regulatory Element Binding Protein 1 / Q000096:biosynthesis / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics*; D000217:Acyltransferases; D054512:Phospholipases A2, Calcium-Independent
chemical_list: D023081:CCAAT-Binding Factor; D007328:Insulin; D008049:Lipase; D008565:Membrane Proteins; D051780:Sterol Regulatory Element Binding Protein 1; C497387:SREBF1 protein, human; C402244:nuclear factor Y; C533682:PNPLA3 protein, human; D000217:Acyltransferases; D054512:Phospholipases A2, Calcium-Independent