Multidrug resistance 3 (MDR3) is present on the canalicular membrane of the hepatocyte and plays an important role in protecting the liver from bile acids. In this study, we characterized the transcriptional effects of four common haplotypes and four polymorphic variants in the promoter region of MDR3 that were identified in 126 DNA samples from Koreans. We measured the luciferase activities of the four MDR3 promoter haplotypes using in vitro reporter assays. Among them, two haplotypes showed a significant decrease in reporter activity compared to the reference. One of the mechanisms by which these haplotypes might decrease MDR3 transcriptional activity was determined: one of the polymorphisms that are present in haplotype 3, was associated with a significant reduction in the promoter activity of MDR3, and the transcription factor NF-Y was predicted to bind to the promoter in the region of g.-1584C>T. Electrophoretic mobility shift assays showed that the g.-1584C allele exhibited greater binding to NF-Y than did the g.-1584T allele. Through the measurement of promoter activity after the overexpression of NF-Y, we found that NF-Y can act as a transcriptional activator of MDR3. These data suggest that the reduced transcriptional activity of g.-1584C>T results from a reduction in the binding affinity of the activator NF-Y to the MDR3 promoter region. Our study suggests that two common haplotypes of MDR3 can regulate the transcriptional rate of MDR3 and that NF-Y may be one of the transcriptional factors involved in this regulation.
|Number of pages||7|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - 25 Jan 2013|
Bibliographical noteFunding Information:
This study was supported by National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) [2010-0003262] ; and a grant of the National Project for Personalized Genomic Medicine, Ministry for Health & Welfare, Republic of Korea [ A111218-PG03 ]. We thank Dr. I. Jang and Dr. J. Cho for giving us a great help to get genomic samples from the DNA bank of Korea Pharmacogenomics Research Network at Seoul National University, Seoul, Korea.