Arylhydrocarbon receptor

Synonym(s)

AhR

Evolutionary old, highly conserved cytoplasmic protein that is expressed by all cells of the epidermis. UVB rays lead to the activation of the arylhydrocarbon receptor via FICZ, a photoproduct generated by photooxidation, which is derived from the amino acid tryptophane. The system operates like steroid hormones; AhR is located in the cytoplasm, migrates into the cell nucleus after binding of the low-molecular agonist, complexes with another protein and binds to target genes. The consecutive AhR signalling cascade can apparently also induce skin ageing through the dysregulation of clock genes. This cascade may also interact with the estrogen receptor (ER) signalling cascade (estrogen-induced pigmentation!). Furthermore, the disruption of this signaling cascade may be associated with premature skin aging. The AhR is known as "dioxin receptor" and is also a well-known sensor for a number of low-molecular environmental substances (dioxin leads to a strong hyperactivation of AhR).
Remarkably, Malazessia furfur is able to alter skin pimentation via malazessin, a natural ligand of AhR.

Esser C et al (2010) UV radiation and pigmentation. dermatologist 61: 561-565
Fritsche E et al (2007): Lightening up the UV response: The AhR is a cytoplasmic photosensor. Proc Natl Acad Sci 104:8851-8856.