Linked Life Data

12815159

Source:http://linkedlifedata.com/resource/pubmed/id/12815159

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2003-6-19
pubmed:abstractText
CYP3A4, the predominant but variably expressed cytochrome P450 of adult human liver, is subject to multifaceted constitutive regulation as well as transcriptional induction by a variety of structurally unrelated xenobiotics. Using transient transfections in HepG2 cells, we previously demonstrated the existence of a potent xenobiotic-responsive enhancer module located between - 7.2 and - 7.8 kilobases upstream of the CYP3A4 transcription start site. Induction is mediated by interaction of transcription factor binding sites in the XREM with the nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR). To determine the in vivo relevance of these findings and to establish a mouse model of human CYP3A4 regulation, we have generated transgenic mice carrying constructs comprising the upstream regulatory region of the human CYP3A4 gene linked to the lacZ reporter gene. Constitutive expression was observed in a developmental, tissue- and cell-specific fashion that mirrors the human situation. In addition, robust hepatic and intestinal induction with a range of reagents known to activate PXR and/or CAR (e.g., dexamethasone, pregnenolone 16alpha-carbonitrile, and phenobarbital) was observed. However, no expression or induction was apparent with a construct lacking upstream sequences beyond - 3.2 kilobases. Histochemical staining for beta-galactosidase activity revealed that dose-dependent increases in transgene levels were associated with a zonal expansion of lacZ expressing hepatocytes, suggesting that xenobiotic induction of CYP3A genes operates primarily through the recruitment of more cells committed to expression. In summary, CYP3A4/lacZ transgenic mice provide an in vivo model for the study of the molecular mechanisms involved in the regulation of a significant human drug metabolizing enzyme.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0026-895X
pubmed:author
pubmed:issnType
Print
pubmed:volume
64
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
42-50
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
Transgenic mouse models of human CYP3A4 gene regulation.
pubmed:affiliation
Department of Clinical Medicine, University of Sydney, Molecular Pharmacology Laboratory. Westmead Millenium Institute, Westmead Hospital, Westmead, Australia.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't