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Regulatory sequence responsible for insulin destabilization of cytochrome P450 2B1 (CYP2B1) mRNA.

ABSTRACT: Diabetes has been reported to increase CYP2E1 (cytochrome P450) and CYP2B1 expression at both the mRNA and protein levels in rat livers. This increase has been attributed to mRNA stabilization and can be reversed by daily insulin treatment. In a previous study, we showed that this hormone directly down-regulates CYP2E1 and 2B1 expression through a post-transcriptional mechanism in rat hepatoma cell lines. We then aimed to identify the molecular mechanisms involved in this regulation. We first identified a 16-mer sequence that we later showed to be the actual functional target of insulin on the rat CYP2E1 mRNA. Similar work was performed with CYP2B1. We first investigated the presence of mRNA-protein interactions. Using cytoplasmic proteins of Fao cells treated or not with insulin (0.1 microM) and the full-length CYP2B1 mRNA as a probe, a major CYP2B1 RNA-protein complex was observed with RNase T1 protection experiments. With the use of different CYP2B1 mRNA probes and by means of competition experiments with antisense oligonucleotides, a protein fixation site was located on a 16-nt sequence in the 5' part of the coding region. This sequence has a hairpin loop structure, shows 80% sequence identity with a structure previously identified on CYP2E1 and is also responsible for the post-transcriptional effects of insulin on this mRNA. Protein(s) bound to both CYP2B1 and CYP2E1 sequences are cytosolic and have an apparent molecular mass of 60 kDa. The protein(s) that bind(s) to both these sequences and the insulin transduction signal involved in this regulation remain(s) to identified.

SUBMITTER: Truong NT

PROVIDER: S-EPMC1186711 | biostudies-other | 2005 May

REPOSITORIES: biostudies-other

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Cytochrome P450 enzymes

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A regulatory loop involving the cytochrome P450-soluble epoxide hydrolase axis and TGF-b signaling

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Acyclic nucleoside phosphonates: a study on cytochrome P450 gene expression

Project description:Focused on the cytochromes P450 (CYPs), we studied gene expression changes in mice treated with acyclic nucleoside antivirals adefovir and tenofovir. Positive control group was treated by prototypic CYP inducers phenobarbital and beta-naphthoflavone. Expression profiling with Steroltalk cDNA arrays revealed major changes in CYP mRNA expression in the inducers-treated group but only minor changes in CYP expression in the adefovir and tenofovir groups.

2014-06-03 | GSE47698 | GEO

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