title: Transcriptional regulation of PCFT by KLF4, HNF4α, CDX2 and C/EBPα: implication in its site-specific expression in the small intestine.
abstract: Proton-coupled folate transporter (PCFT), which is responsible for the intestinal uptake of folates and analogs, is expressed only in the proximal region in the small intestine. The present study was to examine its transcriptional regulation, which may be involved in such a unique expression profile and potentially in its alteration, using dual-luciferase reporter assays in human embryonic kidney (HEK) 293 cells. The luciferase activity derived from the reporter construct containing the 5'-flanking sequence of -1695/+96 of the human PCFT gene was enhanced most extensively by the introduction of Krüppel-like factor 4 (KLF4). The KLF4-induced luciferase activity was further enhanced by hepatocyte nuclear factor 4α (HNF4α) synergistically. To the contrary, caudal-type homeobox transcription factor 2 (CDX2) and CCAAT/enhancer-binding protein α (C/EBPα) extensively suppressed the luciferase activity induced by KLF4 alone and also that induced by KLF4 and HNF4α. Western blot analysis using the rat small intestine indicated uniform expression of KLF4 along the intestinal tract, proximal-oriented expression of HNF4α, distal-oriented expression of CDX2 and C/EBPα. These results suggest that the activity of PCFT promoter is basically induced by KLF4 and the gradiented expression profile of PCFT may be at least in part accounted for by those of HNF4α, CDX2 and C/EBPα.
authors: Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Nagoya 467-8603, Japan.
authors: Mai
authors: M
authors: Furumiya
authors: Katsuhisa
authors: K
authors: Inoue
authors: Kinya
authors: K
authors: Ohta
authors: Yayoi
authors: Y
authors: Hayashi
authors: Hiroaki
authors: H
authors: Yuasa
mesh_terms: D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000378:metabolism*; D000071616:CDX2 Transcription Factor; D019175:DNA Methylation; D017930:Genes, Reporter; D057809:HEK293 Cells; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism*; D008156:Luciferases / Q000235:genetics; D008297:Male; D011401:Promoter Regions, Genetic; D058979:Proton-Coupled Folate Transporter / Q000235:genetics*; D051381:Rats; D017208:Rats, Wistar; D015533:Transcriptional Activation
chemical_list: D022763:CCAAT-Enhancer-Binding Protein-alpha; D000071616:CDX2 Transcription Factor; C491270:CDX2 protein, human; C496592:HNF4A protein, human; D051557:Hepatocyte Nuclear Factor 4; D018398:Homeodomain Proteins; C000715467:KLF4 protein, human; C000715469:Klf4 protein, rat; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D058979:Proton-Coupled Folate Transporter; C505058:SLC46A1 protein, human; D008156:Luciferases