کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5859075 1562319 2015 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
A food contaminant ochratoxin A suppresses pregnane X receptor (PXR)-mediated CYP3A4 induction in primary cultures of human hepatocytes
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم محیط زیست بهداشت، سم شناسی و جهش زایی
پیش نمایش صفحه اول مقاله
A food contaminant ochratoxin A suppresses pregnane X receptor (PXR)-mediated CYP3A4 induction in primary cultures of human hepatocytes
چکیده انگلیسی


- Ochratoxin A supresses rifampicin-inducible activation of pregnane X receptor.
- Ochratoxin A supresses rifampicin-mediated induction of CYP3A4 in human hepatocytes.
- Ochratoxin A speeds up the decline in PXR mRNA via induction of miR-148a

Ochratoxin A (OCHA) is a mycotoxin, which can be found in food such as coffee, wine, cereals, meat, nuts. Since it is absorbed via gastrointestinal tract, it is reasonable to anticipate that the liver will be the first organ to which OCHA comes into the contact before systemic circulation. Many xenobiotics are metabolically modified after the passage of the liver to biologically more active substances, sometimes with more harmful activity. Promoting own metabolism is often achieved via transcriptional regulation of biotransformation enzymes through ligand-activated transcription factors. Pregnane X receptor (PXR) belongs to such a group of regulators and it was demonstrated to be activated by many compounds of synthetic as well as natural origin. Our intention was to investigate if OCHA is capable of activating the PXR with consequent induction of PXR-regulated CYP3A4 gene.We found that OCHA does not activate PXR but displays antagonist-like behavior when combined with rifampicin (RIF) in gene reporter assay in human embryonal kidney cells (Hek293T). It was very weak inducer of CYP3A4 mRNA in primary cultures of human hepatocytes and it antagonized RIF-mediated CYP3A4 induction of mRNA as well as protein. In addition, it caused the decline of PXR protein as well as mRNA which was faster than that with actinomycin D, a transcription inhibitor. Since we found that OCHA induced the expression of miR-148a, which was described to regulate PXR expression, we conclude that antagonist-like behavior of OCHA is not due to the antagonism itself but due to the downregulation of PXR gene expression. Herein we provide important findings which bring a piece of puzzle into the understanding of mechanism of toxic action of ochratoxin A.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Toxicology - Volume 337, 4 November 2015, Pages 72-78
نویسندگان
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