CYP1B1

Dioxin receptor

TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), or dioxin, is a prototype for a large class of halogenated aromatic hydrocarbons that are both widespread and persistent chemical pollutants.

Dioxin produces a broad spectrum of toxic responses and is a potent carcinogen and tumor-promoting agent in rodents. In humans, the skin appears to be the most common target organ, and the abnormalities are collectively termed chloracne.

Chloracne is characterized by the formation of follicular keratinaceous cysts that may be accompanied by thickening and hyperkeratinization of the interfollicular epidermis.

The biologic effects of dioxin are mediated through its high affinity and saturable binding to the dioxin receptor (MIM.126110). This receptor is a member of a distinct class of helix-loop-helix transcription factors.

As characterized for cytochrome P450A1 (CYP1A1) (MIM.108330), activation of transcription of dioxin-inducible genes occurs through the binding of the ligand-occupied dioxin receptor to specific DNA recognition sequences within a dioxin-responsive enhancer, found upstream of the mRNA initiation site.

Pathology

 germline mutations of CYP1A1 in autosomal recessive primary congenital glaucoma type 3A (buphthalmos) (GLC3A) (MIM.231300).