Identification of a novel mechanism of regulation of Ah (dioxin) receptor function

  1. Junsei Mimura,
  2. Masatsugu Ema,
  3. Kazuhiro Sogawa, and
  4. Yoshiaki Fujii-Kuriyama1
  1. Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan

Abstract

Ah receptor (AhR) is a ligand-activated transcription factor that mediates pleiotropic effects of environmental pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin on host animals. In addition to induction of drug-metabolizing enzymes, the liganded AhR complex was found to activate gene expression of a factor designated AhR repressor (AhRR), which inhibits AhR function by competing with AhR for dimerizing with Arnt and binding to the XRE sequence. Thus, AhR and AhRR form a regulatory circuit in the xenobiotic signal transduction pathway and provide a novel mechanism of regulation of AhR function that may determine tissue-specific sensitivity to environmental pollutants.

Keywords

Footnotes

  • 1 Corresponding author.

  • E-MAIL ykfujii{at}mail.cc.tohoku.ac.jp; FAX 81-22-217-6594.

    • Received September 18, 1998.
    • Accepted November 10, 1998.
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