title: UVA-induced modification of catalase charge properties in the epidermis is correlated with the skin phototype.
abstract: The harmful effects of UVA radiation (320-400 nm) on the skin have been related to the generation of reactive oxygen species. Pheomelanin, the pigment characteristic of fair-skinned individuals, amplifies these effects. In vitro, in the presence of photosensitizing agents, UVA light produces singlet oxygen, which reacts with several targets. We have investigated a possible correlation between melanin-type and the antioxidant defense system after UV, focusing on the activities of superoxide dismutase and catalase, which correlated with the phototype of epidermal reconstructs. UVA was more effective than UVB in damaging these enzymatic activities, especially catalase. Furthermore, UVA irradiation induced a free-radical-mediated damage in the cells, leading to an oxidation of cell proteins. On catalase, synthetic pheomelanin amplified this effect on specific targets, such as residues of tryptophan and methionine. UVA irradiation of low phototype reconstructed epidermis and of U937 through synthetic pheomelanin induced a modification in the electrophoretic properties of native catalase, which was counteracted by histidine, a quencher of singlet oxygen. These results demonstrate that pheomelanin could act as a photosensitizing agent, following UVA irradiation, inducing charge modifications of native catalase, by a mechanism involving singlet oxygen or its downstream products.
authors.affiliation: San Gallicano Dermatological Institute IRCCS, Rome, Italy.
authors.forename: Vittoria
authors.initials: V
authors.lastname: Maresca
authors.forename: Enrica
authors.initials: E
authors.lastname: Flori
authors.forename: Stefania
authors.initials: S
authors.lastname: Briganti
authors.forename: Emanuela
authors.initials: E
authors.lastname: Camera
authors.forename: Muriel
authors.initials: M
authors.lastname: Cario-André
authors.forename: Alain
authors.initials: A
authors.lastname: Taïeb
authors.forename: Mauro
authors.initials: M
authors.lastname: Picardo
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D002374:Catalase / Q000378:metabolism*; D002478:Cells, Cultured; D003548:Cysteinyldopa / Q000494:pharmacology; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D004817:Epidermis / Q000187:drug effects / Q000201:enzymology* / Q000528:radiation effects*; D006801:Humans; D008543:Melanins / Q000494:pharmacology*; D008544:Melanocytes / Q000201:enzymology / Q000528:radiation effects; D008715:Methionine / Q000378:metabolism; D010084:Oxidation-Reduction; D017319:Photosensitizing Agents / Q000494:pharmacology*; D026082:Singlet Oxygen / Q000378:metabolism; D012867:Skin / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D013482:Superoxide Dismutase / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D008543:Melanins; D017319:Photosensitizing Agents; C018362:pheomelanin; D026082:Singlet Oxygen; D003548:Cysteinyldopa; D004295:Dihydroxyphenylalanine; C040616:DOPA melanin; D014364:Tryptophan; D008715:Methionine; D002374:Catalase; D013482:Superoxide Dismutase