title: Correlation between melanogenic and catalase activity in in vitro human melanocytes: a synergic strategy against oxidative stress.
abstract: UV-induced DNA damage can lead to melanoma, the most dangerous form of skin cancer. Understanding the mechanisms employed by melanocytes to protect against UV is therefore a key issue. In melanocytes, catalase is the main enzyme responsible for degrading hydrogen peroxide and we have previously shown that that low basal levels of catalase activity are associated with the light phototype in in vitro and ex vivo models. Here we investigate the possible correlation between its activity and melanogenesis in primary cultures of human melanocytes. We show that while the total melanin concentration is directly correlated to the level of pigmentation, the more the degree of pigmentation increased, the lower the proportion of pheomelanin present. Moreover, in human melanocytes in vitro, catalase-specific mRNA, protein and enzymatic activity were all directly correlated with total cellular melanin content. We also observed that immediately after a peroxidative treatment, the increase in reactive oxygen species was inversely associated with pigmentation level. Darkly pigmented melanocytes therefore possess two protective strategies represented by melanins and catalase activity that are likely to act synergistically to counteract the deleterious effects of UV radiation. By contrast, lightly pigmented melanocytes possess lower levels of melanogenic and catalase activity and are therefore more susceptible to accumulate damage after UV exposition.
authors.affiliation: Laboratory of Cutaneous Physiopathology, San Gallicano Dermatological Institute, 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: Arianna
authors.initials: A
authors.lastname: Mastrofrancesco
authors.forename: Claudia
authors.initials: C
authors.lastname: Fabbri
authors.forename: Anna M
authors.initials: AM
authors.lastname: Mileo
authors.forename: Marco G
authors.initials: MG
authors.lastname: Paggi
authors.forename: Mauro
authors.initials: M
authors.lastname: Picardo
mesh_terms: D015153:Blotting, Western; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D006801:Humans; D008543:Melanins / Q000378:metabolism*; D008544:Melanocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D012333:RNA, Messenger / Q000096:biosynthesis; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012880:Skin Pigmentation / Q000502:physiology
chemical_list: D008543:Melanins; D016877:Oxidants; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D002374:Catalase; D014442:Monophenol Monooxygenase