Transcriptional regulation of PCFT by KLF4, HNF4¦Á, CDX2 and C/EBP¦Á: Implication in its site-specific expression in the small intestine

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• 作者：Mai Furumiya^a ; ^b ; Katsuhisa Inoue^a ; Kinya Ohta^a ; Yayoi Hayashi^b ; Hiroaki Yuasa^a ; ^{yuasa@phar.nagoya-cu.ac.jp}
• 关键词：PCFT ; Gene expression ; Transcriptional regulation ; Intestine ; KLF4 ; HNF4¦Á ; CDX2 ; C/EBP¦Á
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2013
• 出版时间：8 February, 2013
• 年：2013
• 卷：431
• 期：2
• 页码：158-163
• 全文大小：574 K

文摘

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¡ä-flanking sequence of ?1695/+96 of the human PCFT gene was enhanced most extensively by the introduction of Kr¨¹ppel-like factor 4 (KLF4). The KLF4-induced luciferase activity was further enhanced by hepatocyte nuclear factor 4¦Á (HNF4¦Á) synergistically. To the contrary, caudal-type homeobox transcription factor 2 (CDX2) and CCAAT/enhancer-binding protein ¦Á (C/EBP¦Á) extensively suppressed the luciferase activity induced by KLF4 alone and also that induced by KLF4 and HNF4¦Á. Western blot analysis using the rat small intestine indicated uniform expression of KLF4 along the intestinal tract, proximal-oriented expression of HNF4¦Á, distal-oriented expression of CDX2 and C/EBP¦Á. 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 HNF4¦Á, CDX2 and C/EBP¦Á.