Molecular characterization and developmental expression of the aryl hydrocarbon receptor from the chick embryo

Mary K. Walker, Scott E. Heid, Susan M. Smith, Hollie I. Swanson

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


The aryl hydrocarbon receptor (AhR) was cloned from the chick embryo and its function and developmental expression characterized. Chicken AhR cDNA coded for 858 amino acid protein and 396 bp of 3' UTR. The basic helix-loop- helix domain exhibited 87-100% amino acid identity to avian, mammalian, and amphibian AhR, and 69-74% to piscine AhR. The PAS (Per-ARNT-Sim) region was slightly less well conserved with (a) 97% identity to other avian sequences, (b) 81-86% to amphibian and mammalian AhR, and (c) 64-69% with piscine AhR. The carboxy terminus diverged the most among species with less than 53% amino acid identity between chicken and any available mammalian and piscine AhR sequences. The chicken AhR mRNA and protein were 6.1 kb and 103 kDa, respectively. Chicken AhR dimerized with human AhR nuclear translocator and bound the mammalian dioxin-response element in a ligand-dependent manner. AhR protein was detected in neural ganglia; smooth, cardiac, and skeletal muscle; and epithelium involved in epithelial-to-mesenchymal transformations, such as pituitary, gastrointestinal tract, limb apical-ectodermal ridge, and kidney collecting ducts. AhR mRNA was detected in all tissues expressing protein, except myocardium. Cytochrome P4501A4 mRNA was highly induced by 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD) in a subset of tissues expressing AhR, including small intestine, liver, kidney, blood vessels, and outflow tract myocardium. In conclusion, the AhR sequence and function is highly conserved between birds and mammals, and although many tissues express AhR during chick embryo development, only a subset are responsive to TCDD induction of CYP1A4. (C) 2000 Elsevier Science Inc.

Original languageEnglish
Pages (from-to)305-319
Number of pages15
JournalComparative Biochemistry and Physiology - C Pharmacology Toxicology and Endocrinology
Issue number3
StatePublished - Jul 2000

Bibliographical note

Funding Information:
The authors thank Dr Ed Krug, Medical University of South Carolina, Charleston, SC for the generous gift of the chick embryo heart cDNA library; Dr Richard Pollenz, University of South Florida, Tampa, FL for the AhR and ARNT antibodies; Dr Mark Hahn, Woods Hole Oceanographic Institute, Woods Hole, MA, for sharing his unpublished full-length chicken AhR sequence; and Tom Catron and Susan Quintana for their technical assistance. This research was supported, in part, by NIH #BH953016; American Heart Association, Wisconsin Affiliate # 96-GB-77; ACI IRG #192, and NIH ES 09804-01A1.


  • 2,3,7,8-tetrachlorodibenzo-p- dioxin
  • Aryl hydrocarbon nuclear translocator
  • Aryl hydrocarbon receptor
  • CYP1A1
  • CYP1A4
  • Chick embryo
  • Cytochrome P4501A4
  • TCDD

ASJC Scopus subject areas

  • Immunology
  • Pharmacology


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