Basal expression of the rat, but not of the human, multidrug resistance protein 2 (MRP2) gene is mediated by CBF/NF-Y and Sp1 promoter-binding sites

Toxicology. 2001 Oct 5;167(1):25-35. doi: 10.1016/s0300-483x(01)00455-3.

Abstract

The most important biliary efflux transporter known so far is the multidrug resistance protein 2 (MRP2). Previously, we isolated and characterized the 5'-flanking region of the rat mrp2 gene. In the present study, we performed site-directed mutagenesis experiments indicating that both a Y-Box and a GC-Box in the rat mrp2 promoter are essential for the full basal expression of the gene, but have no significant relevance for its inducibility by the chemical carcinogen 2-acetylaminofluorene. Gel mobility shift experiments demonstrated the binding of the transcription factor CBF/NF-Y, but not of EFIA/YB-1, to the Y-Box. Site-directed mutations in the Y-Box decreasing reporter gene activity of a promoter construct prevented the binding of NF-Y. Consequently, NF-Y contributes substantially to the basal expression of the gene. A site-directed mutation in the GC-Box also reduced basal expression and resulted in a reduced complex formation with the transcription factor Sp1. The corresponding region of the human MRP2 promoter comprises no Sp1 site, but a Y-Box-like element binding YB-1 but not NF-Y, which, however, does not contribute to basal expression. In conclusion, NF-Y and Sp1 binding sites play a decisive role in the basal expression of the rat mrp2 gene, while the human MRP2 gene is regulated differently.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 2-Acetylaminofluorene / pharmacology
  • ATP Binding Cassette Transporter, Subfamily B / biosynthesis*
  • ATP Binding Cassette Transporter, Subfamily B / genetics
  • ATP Binding Cassette Transporter, Subfamily B / metabolism
  • ATP-Binding Cassette Transporters*
  • Animals
  • Binding Sites
  • CCAAT-Binding Factor / metabolism*
  • Carcinogens / pharmacology
  • Carcinoma, Hepatocellular / genetics
  • Carcinoma, Hepatocellular / metabolism
  • Carrier Proteins / biosynthesis*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Gene Expression Regulation, Neoplastic* / drug effects
  • Humans
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism
  • Liver Neoplasms, Experimental / genetics
  • Liver Neoplasms, Experimental / metabolism
  • Membrane Transport Proteins*
  • Multidrug Resistance-Associated Protein 2
  • Multidrug Resistance-Associated Proteins*
  • Mutagenesis, Site-Directed / physiology
  • Promoter Regions, Genetic
  • Rats
  • Sp1 Transcription Factor / metabolism*
  • Transfection
  • Tumor Cells, Cultured

Substances

  • ABCC2 protein, human
  • ATP Binding Cassette Transporter, Subfamily B
  • ATP-Binding Cassette Transporters
  • Abcc2 protein, rat
  • CCAAT-Binding Factor
  • Carcinogens
  • Carrier Proteins
  • Membrane Transport Proteins
  • Multidrug Resistance-Associated Protein 2
  • Multidrug Resistance-Associated Proteins
  • Sp1 Transcription Factor
  • 2-Acetylaminofluorene
  • multidrug resistance-associated protein 1