title: Human liver fatty acid binding protein (hFABP1) gene is regulated by liver-enriched transcription factors HNF3β and C/EBPα.
abstract: The human liver fatty acid binding protein (hFABP1) participates in cellular long-chain fatty acid trafficking and regulation of lipid metabolism and changes in hFABP1 are associated with an increased risk for type 2 diabetes, cardiovascular disease (CVD), and metabolic syndromes. Gene regulation of hFABP1 is not fully understood. Therefore, in the present study, the full length hFABP1 promoter (nucleotides -2125 to +51) and a series of truncated promoter regions were cloned. A luciferase reporter assay revealed that nucleotides -255 to +50 in the promoter region contained full of maximum hFABP1 promoter activity compared with the full length promoter. Furthermore high activity was shown when the plasmid was transfected into liver-derived cells such as the human hepatoblastoma cell line HepG2 and the hepatoma cell line Huh7. TFSEARCH and TESS programs were used to predict potential transcription factor binding sites. Two putative binding sites for the liver-enriched transcription factors hepatocyte nuclear factor 3β (HNF3β) and CCAAT/enhancer binding protein α (C/EBPα) were identified in the -255 nt to -155 nt hFABP1 promoter region. Site-directed mutagenesis of these two sites reduced dramatically hFABP1 promoter activity. In addition, the electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation assay (ChIP) revealed that these binding sites were recognized by HNF3β and C/EBPα respectively. Overexpression of HNF3β and C/EBPα enhanced the transcription of hFABP1 and consequently improved the protein level of hFABP1 in HepG2 cells, while knockdown of HNF3β and C/EBPα showed the inverse effects. Taken together, the hFABP1 gene is highly transcribed in liver-derived cells, and regulated predominantly by liver-enriched transcription factors HNF3β and C/EBPα.
authors.affiliation: Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Research Center of Molecular Medicine, Fujian Medical University, Fuzhou City 350004, PR China.
authors.forename: Yun-li
authors.initials: YL
authors.lastname: Wu
authors.forename: Xian-e
authors.initials: XE
authors.lastname: Peng
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Wan-nan
authors.initials: WN
authors.lastname: Chen
authors.forename: Xu
authors.initials: X
authors.lastname: Lin
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D024202:Electrophoretic Mobility Shift Assay; D050556:Fatty Acid-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D017930:Genes, Reporter; D051542:Hepatocyte Nuclear Factor 3-beta / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D050356:Lipid Metabolism / Q000235:genetics*; D008099:Liver / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015398:Signal Transduction; D015533:Transcriptional Activation / Q000235:genetics*; D014162:Transfection
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C515848:CEBPA protein, human; C493319:FABP1 protein, human; C496502:FOXA2 protein, human; D050556:Fatty Acid-Binding Proteins; D005227:Fatty Acids; D051542:Hepatocyte Nuclear Factor 3-beta