Elsevier

Gene

Volume 158, Issue 2, 9 June 1995, Pages 263-268
Gene

Short communication
Localization of a phenobarbital-responsive element (PBRE) in the 5′-flanking region of the rat CYP2B2 gene

https://doi.org/10.1016/0378-1119(94)00916-GGet rights and content

Abstract

Cytochrome P450 2B1, encoded by CYP2B1, and cytochrome P450 2B2, encoded by CYP2B2, are inducible in rat liver by phenobarbital (PB). We have used cultured adult rat hepatocytes to study molecular mechanisms regulating CYP2B1/CYP2B2 transcription. Northern blot analysis demonstrated that the endogenous CYP2B1/CYP2B2 genes were inducible by PB in such cultures. A PB-responsive element (PBRE) conferring PB inducibility on a reporter gene was identified in the CYP2B2 5′-flanking region. The PBRE was localized to a 163-bp Sau3AI fragment situated between 2155 and 2318 by upstream from the CYP2B2 transcription start point (tsp). The PBRE also conferred PB responsiveness on an enhancerless heterologous promoter and was active in both orientations both upstream and downstream from the heterologous promoter; hence, it has the properties of a transcriptional enhancer. Gel-retardation assays showed that nuclear extracts of liver cells of untreated and PB-treated rats contained sequence-specific DNA-binding factors that interact with a PBRE-containing DNA fragment. These results may open the way to identifying one or more transcription factors mediating induction of CYP2B2 and CYP2B1 in rat liver.

References (26)

  • B. Seed et al.

    A simple phase-extraction assay for chloramphenicol acyltransferase activity

    Gene

    (1988)
  • J.S. Sidhu et al.

    Influence of extracellular matrix overlay on phenobarbital-mediated induction of CYP2B1, 2B2, and 3A1 genes in primary adult rat hepatocyte culture

    Arch. Biochem. Biophys.

    (1993)
  • M. Affolter et al.

    cDNA clones for liver cytochrome P-450s from individual Aroclor-treated rats: constitutive expression of a new P-450 gene related to phenobarbital-inducible forms

    DNA

    (1986)
  • Cited by (164)

    • Insights into CYP2B6-mediated drug-drug interactions

      2016, Acta Pharmaceutica Sinica B
      Citation Excerpt :

      Over the years, researchers have observed potent induction of CYP2B genes by barbiturates in the liver of many different species. The first study illustrating molecular mechanisms behind this induction came in 1995 using cultured adult rat hepatocytes124. A functional analysis of the 5ʹ flanking promoter region of rat Cyp2b1 and Cyp2b2 has linked PB-mediated induction to a 163-bp DNA sequence, termed the PB-responsive element (PBRE) or PB-responsive unit (PBRU), located −2155 to 2318 bp from the transcription start site of Cyp2b1/2124,125.

    • Induction of a detoxification gene in Drosophila melanogaster requires an interaction between tissue specific enhancers and a novel cis-regulatory element

      2011, Insect Biochemistry and Molecular Biology
      Citation Excerpt :

      The barbiturate compound Phenobarbital (PB) has been extensively used to study the induction mechanism of mammalian P450 genes. Reporter gene assays in cultured adult rat hepatocytes were used to identify a 163 bp PB responsive element (PBRE) in the regulatory region of the rat P450 gene CYP2B2 (Trottier et al., 1995). This PBRE was subsequently shown to be active in adult rat liver (Park et al., 1996).

    • Interplay between cholesterol and drug metabolism

      2011, Biochimica et Biophysica Acta - Proteins and Proteomics
    View all citing articles on Scopus
    View full text