title: Does melanin matter in the dark?
abstract: In living cells, melanin pigment is formed within melanosomes, which not only protect the cells from autodestruction, but also serve as second messenger organelles regulating important skin functions, with melanocytes acting as primary sensory and regulatory cells of the epidermis. Yet, one can argue that skin melanin, which may negatively affect cellular homeostasis in melanoma, really exerts protective functions. Consequently, the actual functions of melanin and the melanogenic pathway in skin biology remains enigmatic. Yet, the solution of this riddle seems simple - to check the actual influence of natural melanin on skin cells in the dark. Since many interesting hypotheses and theories put forward in this respect did not survive confrontation with the experiment, a leading pigment research group from Naples was brave to "jump off the cliff" by confronting theory with experimental reality. They showed that, in the dark, human hair-derived melanin promotes inflammatory responses in keratinocytes, lowers their viability, promotes oxidative stress, and that pheomelanin does so more strongly than eumelanin. Thus, pheomelanin hardly protects red-haired individuals, even when avoiding the sun. Black hairs do not do much better either, unless they undergo graying.
authors.affiliation: Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Przemysław M
authors.initials: PM
authors.lastname: Płonka
authors.affiliation: Cutaneous Physiopathology Laboratory and Metabolomic Center, San Gallicano Dermatological Institute, Rome, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Picardo
authors.affiliation: Department of Dermatology, University of Alabama at Birmingham, AL, USA.|Laboratory Service of the VA Medical Center, Birmingham, AL, USA.
authors.forename: Andrzej T
authors.initials: AT
authors.lastname: Slominski
mesh_terms: D002470:Cell Survival; D003624:Darkness; D004817:Epidermis / Q000378:metabolism; D006200:Hair Color; D006801:Humans; D007249:Inflammation; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D008027:Light; D008543:Melanins / Q000737:chemistry / Q000502:physiology*; D008544:Melanocytes / Q000378:metabolism; D020460:Melanosomes / Q000378:metabolism; D018384:Oxidative Stress; D012867:Skin / Q000378:metabolism*; D012880:Skin Pigmentation
chemical_list: D008543:Melanins; C018362:pheomelanin; C041877:eumelanin
keywords: inflammation; keratinocytes; melanocytes; protection; toxicity