DEC1 binding to the proximal promoter of CYP3A4 ascribes to the downregulation of CYP3A4 expression by IL-6 in primary human hepatocytes.
In this study, we provided molecular evidences that interleukin-6 (IL-6) contributed to the decreased capacity of oxidative biotransformation in human liver by suppressing the expression of cytochrome P450 3A4 (CYP3A4). After human hepatocytes were treated with IL-6, differentially expressed in chondrocytes 1 (DEC1) expression rapidly increased, and subsequently, the CYP3A4 expression decreased continuously. Furthermore, the repression of CYP3A4 by IL-6 occurred after the increase of DEC1 in primary human hepatocytes. In HepG2 cells, knockdown of DEC1 increased the CYP3A4 expression and its enzymatic activity. In addition, it partially abolished the decreased CYP3A4 expression as well as its enzymatic activity induced by IL-6. Consistent with this, overexpression of DEC1 markedly reduced the CYP3A4 promoter activity and the CYP3A4 expression as well as its enzymatic activity. Using sequential truncation and site directed mutagenesis of CYP3A4 proximal promoter with DEC1 construct, we showed that DEC1 specifically bound to CCCTGC sequence in the proximal promoter of CYP3A4, which was validated by EMSA and ChIP assay. These findings suggest that the repression of CYP3A4 by IL-6 is achieved through increasing the DEC1 expression in human hepatocytes, the increased DEC1 binds to the CCCTGC sequence in the promoter of CYP3A4 to form CCCTGC-DEC1 complex, and the complex downregulates the CYP3A4 expression and its enzymatic activity.
Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.|Nanjing Jinling Hospital, 210002.
Mao
M
Zhao
Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
Luan
L
Xiaofei
Nanjing Jinling Hospital, 210002.
Cao
C
Gang
Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
Liu
L
Wei
Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
Xiong
X
Jing
Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
Hu
H
Gang
Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
Chen
C
Ruini
Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
Ning
N
Rui
Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
Shang
S
Wei
Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu 210029, China.
Yang
Y
Jian
Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, 02881, USA.
Yan
Y
Bingfang
D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism*; D017931:DNA Primers; D015536:Down-Regulation / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D015850:Interleukin-6 / Q000502:physiology*; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
C403671:DELEC1 protein, human; D017931:DNA Primers; D015850:Interleukin-6; D025521:Tumor Suppressor Proteins; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human