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Transcriptional regulation of chicken cytochrome P450 2D49 basal expression by CCAAT /enhancer‐binding protein α and hepatocyte nuclear factor 4α
Author(s) -
Yang Qi,
Tang Shulin,
Dong Linfeng,
Chen Qingmei,
Liu Xin,
Jiang Jun,
Deng Yiqun
Publication year - 2014
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.12710
Subject(s) - transcription factor , microbiology and biotechnology , ccaat enhancer binding proteins , hepatocyte nuclear factor 4 , chromatin immunoprecipitation , hepatocyte nuclear factors , biology , enhancer , electrophoretic mobility shift assay , promoter , transcription (linguistics) , binding site , chromatin , nuclear protein , gene expression , gene , genetics , nuclear receptor , linguistics , philosophy
Chicken cytochrome P450 ( CYP )2D49 is structurally and functionally related to human CYP 2D6, which is an important drug‐metabolizing enzyme. To date, little is known about the transcriptional regulation of this cytochrome. Through deletion analysis of the CYP 2D49 promoter, we identified two putative degenerate CCAAT /enhancer‐binding protein (C/ EBP )‐binding sites and an imperfect DR 1 element (the site contains direct repeats of the hexamer AGGTCA separated by a one‐nucleotide spacer motif) within regions –296/–274, –274/–226, and –226/–183, respectively, which may play critical roles in the transcriptional activation of the CYP 2D49 gene. Electrophoretic mobility shift assays and chromatin immunoprecipitation assays showed that the putative C/ EBP boxes and DR 1 element in the CYP 2D49 promoter are functional motifs that bind to C/ EBP α and hepatocyte nuclear factor 4α ( HNF 4α), respectively. Furthermore, we studied the functional importance and relationships of these transcription factor‐binding sites by examining the effects of mutation and deletion of these regions on promoter activity. These studies revealed that the two C/ EBP ‐binding sites show a compensatory relationship and work cooperatively with the DR 1 element to modulate the transcription of CYP 2D49 . The results of overexpressing C/ EBP α and HNF 4α in culture cells further confirmed that both C/ EBP α and HNF 4α contribute significantly to sustaining a high level of CYP 2D49 transcription. In conclusion, the data indicate that the constitutive hepatic expression of CYP 2D49 is governed by both C/ EBP α and HNF 4α. Further studies will be required to fully characterize the molecular mechanisms that modulate CYP 2D49 expression.