The aryl hydrocarbon receptor (AHR), a novel regulator of human melanogenesis.
Skin cancer, chloracne and hyperpigmentation have been associated with the exposure to environmental contaminants such as polychlorinated biphenyls, dioxins or polycyclic aromatic hydrocarbons. These compounds are xenobiotic high-affinity ligands for the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor with important physiological roles in, for example, the control of cell proliferation and inflammation. We show here that exposure of normal human melanocytes to the most potent dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), results in activation of the AHR signaling pathway and an AHR-dependent induction of tyrosinase activity, the key enzyme of the melanogenic pathway. In accordance with the upregulation of tyrosinase enzyme activity, total melanin content was also elevated in TCDD-exposed melanocytes. Neither the induction of tyrosinase enzyme activity or of total melanin could be attributed to enhanced cell proliferation, but was rather due to the induction of tyrosinase and tyrosinase-related protein 2 gene expression. Thus, the AHR is able to modulate melanogenesis by controlling the expression of melanogenic genes.
Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
Sandra
S
Luecke
Maria
M
Backlund
Bettina
B
Jux
Charlotte
C
Esser
Jean
J
Krutmann
Agneta
A
Rannug
D001665:Binding Sites; D002227:Carbazoles / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D008024:Ligands; D008543:Melanins / Q000096:biosynthesis*; D008544:Melanocytes / Q000187:drug effects / Q000201:enzymology / Q000528:radiation effects; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D014364:Tryptophan / Q000378:metabolism; D014466:Ultraviolet Rays
C111855:6-formylindolo(3,2-b)carbazole; D002227:Carbazoles; D008024:Ligands; D008543:Melanins; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D014364:Tryptophan; D014442:Monophenol Monooxygenase