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Title: The effect of high dose endotoxin on CYP3A2 expression in the rat.

Authors: Roe, A L; Warren, G; Hou, G; Howard, G; Shedlofsky, S I; Blouin, R A

Published In Pharm Res, (1998 Oct)

Abstract: The purpose of our research was two-fold: 1) to further characterize the downregulation of CYP3A2 mRNA, protein, and activity during an acute phase response (APR); 2) most importantly, to relate the time-dependent activation of nuclear proteins to putative DNA binding sequences within the CYP3A2 5'-flanking region, with the loss in CYP3A2 expression.Rats were injected (2.0 mg/animal, i.p.) with LPS and sacrificed at 1, 2, 4, 6, 8, 24, 48, and 72 hours. Hepatic nuclear protein was isolated and analyzed for binding activity to AP-1, NFkappaB, and NF-IL6 consensus sequences. Hepatic CYP3A2 mRNA levels were determined by solution hybridization and CYP3A2 protein, CYP3A2 activity, and total P450 were measured in hepatic microsomes.Computer analysis of the 5'-flanking region of CYP3A2 revealed the presence of 5 NF-IL6 and 4 AP-1 putative DNA binding sites. The strongest increase in AP-1 binding activity occurred between 6 and 24 hr, and the alteration in binding complexes to an NF-IL6 oligonucleotide occurred between 4 and 24 hr. Maximum loss in CYP3A2 mRNA occurred at 8 hr post-LPS injection and remained lowered at the 24 hr timepoint. CYP3A2 protein was significantly decreased at 24, 48, and 72 hours post-LPS treatment with corresponding decreases in CYP3A2 activity and total P450.The changes in NF-IL6 and AP-1 binding after LPS treatment, which appears to correlate with the changes in CYP3A2 mRNA, combined with the presence of putative NF-IL6 and AP-1 sites located in the CYP3A25'-flanking region, may indicate a potential role for NF-IL6 and AP-1 in CYP3A2 downregulation during an APR.

PubMed ID: 9794504 Exiting the NIEHS site

MeSH Terms: Acute-Phase Reaction/metabolism; Animals; CCAAT-Enhancer-Binding Proteins; Cytochrome P-450 Enzyme System/drug effects*; Cytochrome P-450 Enzyme System/genetics; Cytochrome P-450 Enzyme System/metabolism; DNA-Binding Proteins/metabolism; Down-Regulation; Enzyme-Linked Immunosorbent Assay; Lipopolysaccharides/pharmacology*; Male; NF-kappa B/metabolism; Nuclear Proteins/metabolism; RNA, Messenger/analysis; Rats; Rats, Sprague-Dawley; Steroid Hydroxylases/drug effects*; Steroid Hydroxylases/genetics; Steroid Hydroxylases/metabolism; Transcription Factor AP-1/metabolism

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