Structural and Functional Characterization of the 5′-Flanking Region of the Rat and Human Cytochrome P450 2E1 Genes: Identification of a Polymorphic Repeat in the Human Gene

doi:10.1006/bbrc.1999.1362

Biochemical and Biophysical Research Communications

Volume 263, Issue 2, 24 September 1999, Pages 286-293

https://doi.org/10.1006/bbrc.1999.1362 Get rights and content

Abstract

Cytochrome P450 2E1 (CYP2E1) is a toxicologically very important enzyme with a high extent of interindividual variability in expression. We sequenced and characterized the 5′-flanking region of the human and rat CYP2E1 genes. The identity between the human and rat sequences (−3.8 kb to +1 kb) was generally between 35 and 60%, and the most similar regions were found in the proximal part of the sequence. Two more distant regions at −1.6 to −2.0 kb and −2.5 to −2.8 kb in the human sequence were also found to have high identity to the rat sequence. A polymorphic repeat sequence in the human gene was found between −2178 to −1945 bp. The common allele (CYP2E1*1C) contained 6 repeats (each 42–60 bp long) and the rare allele (CYP2E1*1D) had 8 repeats with an allele frequency of 1% among Caucasians and 23% among Chinese. The CYP2E1 5′-flanking regions of the human (−3712 bp to +10 bp) and rat (−3685 bp to +28 bp) genes were ligated in front of a luciferase reporter gene and transfected into rat hepatoma Fao and human hepatoma B16A2 cells. Important species specificity was noted in the control of gene expression and regions of negative and positive cis-acting elements were localized. No difference was seen in the constitutive expression between the two polymorphic forms. The importance of this repeat polymorphism for high and low inducible CYP2E1 phenotypes is discussed.

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^☆: Abbreviations used: PCR, polymerase chain reaction; CYP, cytochrome P450; RFLP, restriction fragment length polymorphism; HNF-1α, hepatocyte nuclear factor −1α

¹: Visiting scientist from the Department of Pharmacology and Toxicology, University of Oulu, Oulu, Finland.

²: To whom correspondence should be addressed at Division of Molecular Toxicology, IMM, Karolinska Institutet, 171 77 Stockholm, Sweden. Fax: +468-337-327. E-mail: [email protected].

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Regular ArticleStructural and Functional Characterization of the 5′-Flanking Region of the Rat and Human Cytochrome P450 2E1 Genes: Identification of a Polymorphic Repeat in the Human Gene☆

Abstract

Toxicol. Appl. Pharmacol.

Toxicol. Appl. Pharmacol.

Toxicol. Appl. Pharmacol.

Alcohol

Biochem. Biophys. Res. Commun.

Biochem. Pharmacol.

Toxicol. Appl. Pharmacol.

Lancet

FEBS Lett.

Pharmacogenetics

Mol. Cell. Biol.

DNA Cell Biol.

Regular Article
Structural and Functional Characterization of the 5′-Flanking Region of the Rat and Human Cytochrome P450 2E1 Genes: Identification of a Polymorphic Repeat in the Human Gene☆