AHR gene

The AHR gene (AHR stands for " Aryl Hydrocarbon Receptor") is a protein-coding gene located on chromosome 7p21.1.

The protein encoded by this gene an aryl hydrocarbon receptor (AHR), is a cytosolic transcription factor involved in the regulation of biological responses to aromatic hydrocarbons.

Aryl hydrocarbon receptors (AHRs) are transcription factors that are bound to co-chaperones in the resting state. Prior to ligand binding, the encoded protein is sequestered in the cytoplasm; after ligand binding, this protein migrates to the nucleus where it heterodimerizes with ARNT (Aryl Hydrocarbon Receptor Nuclear Translocator) and induces transcription by binding to xenobiotic response elements (XRE) (Gomez A et al. 2018).

Ligand binding causes dissociation of co-chaperones, allowing AHR to translocate to the nucleus, dimerize, and alter transcription of target genes.

The AHR receptor has been shown to regulate xenobiotic-metabolizing enzymes (xenobiotics = chemical substances that are not naturally formed but synthesized by humans and are foreign to the biological cycle). such as cytochrome P450.

Diseases associated with AHR include:

Retinitis Pigmentosa

The AHR protein enables cells to adapt to changing conditions by recognizing compounds from the environment, diet, microbiome, and cell metabolism, and which plays an important role in development, immunity, and cancer (MacPherson L et al. 2013).

AHR is traditionally considered a ligand-activated receptor and transcription factor responsible for the induction of enzymes that metabolize drugs. Mediates biochemical and toxic effects of halogenated aromatic hydrocarbons (Puga A et al. (2002).

The AHR receptor encoded AHR protein regulates a variety of biological processes, including angiogenesis, hematopoiesis, drug and lipid metabolism, cell motility, and immune modulation (Puga A et al. 2002).

Apparently, AHR receptors play a major role in UV-induced pigmentation. Thus, these receptors are produced by all cells of the epidermis (keratinocytes, Langerhans cells, melanocytes). In the skin, AhR functions, among other things, as a sensor that recognizes chemical environmental stimuli. Its importance in dermatological research is increasing now that it is known that AHR performs other diverse tasks in the skin, such as in the aging process or in the homeostasis of immune cells.

1. Gomez A et al (2018) Characterization of TCDD-inducible poly-ADP-ribose polymerase (TIPARP/ARTD14) catalytic activity. Biochem J 475:3827-3846.
2. MacPherson L et al. (2013) 2,3,7,8-Tetrachlorodibenzo-p-dioxin poly(ADP-ribose) polymerase (TiPARP, ARTD14) is a mono-ADP-ribosyltransferase and repressor of aryl hydrocarbon receptor transactivation. Nucleic Acids Res 41:1604-1621.
3. Puga A et al (2002). Role of the aryl hydrocarbon receptor in cell cycle regulation. Chem Biol Interact 141:117-130.