Variations in melanin formation by cultured melanocytes from different skin types (original) (raw)
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Melanins and melanogenesis: methods, standard, protocols
2013
Despite considerable advances in the past decade, melanin research still suffers from the lack of universally accepted and shared nomenclature, methodologies and structural models. This paper stems from the joint efforts of chemists, biochemists, physicists, biologists and physicians with recognized and consolidated expertise in the field of melanins and melanogenesis, who critically reviewed and experimentally revisited methods, standards and protocols to provide for the first time a consensus set of recommended procedures to be adopted and shared by researchers involved in pigment cell research. Aim of the paper is the definition of an unprecedented frame of reference built on cuttingedge knowledge and state-of-the-art methodology, to enable reliable comparison of results among laboratories and new progress in the field based on standardized methods and shared information.
Pigment Cell Research, 2006
Cultured human melanocytes differ tremendously in visual pigmentation, and recapitulate the pigmentary phenotype of the donor's skin. This diversity arises from variation in type as well as quantity of melanin produced. Here, we measured contents of eumelanin (EM) and pheomelanin (PM) in 60 primary human melanocyte cultures (51 neonatal and nine adults), and correlated some of these values with the respective activity and protein levels of tyrosinase, and the melanocortin-1 receptor (MC1R) genotype. Melanocytes were classified into four phenotypes (L, L+, D, D+) as depicted by visual pigmentation using light microscopy, and by the pigmentary phenotype of the donor's skin. There were large differences in total melanin (TM) and EM, which increased progressively for L, L+, D and D+ melanocytes. TM content, the sum of EM and PM, showed a good correlation with TM measured spectrophotometrically, and with the activity and protein levels of tyrosinase. Log EM/PM ratio did not correlate with MC1R genotype. We conclude that: (i) EM consistently correlates with the visual phenotype; (ii) lighter melanocytes tend to be more pheomelanic in composition than darker melanocytes; (iii) in adult melanocyte cultures, EM correlates with the ethnic background of the donors (African-American > Indian > Caucasian); and (iv) MC1R loss-of-function mutations do not necessarily alter the phenotype of cultured melanocytes.
Melanins and melanogenesis: methods, standards, protocols
Pigment Cell & Melanoma Research, 2013
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Chemical Analysis of Melanins and its Application to the Study of the Regulation of Melanogenesis
Pigment Cell Research, 2000
show that tyrosinase activity is the most important factor that regulates the tractable chemical properties, the heterogeneity in their switch of melanogenesis, with lower tyrosinase activities fa-structural features, and the lack of methods to split melanin polymers into monomer units. To overcome this difficulty, voring pheomelanogenesis; further suppression of melanogenwe developed a rapid and sensitive method for quantitatively esis results in a lack of pigment production. 3) In cultured analyzing eumelanin and pheomelanin in biological samples melanocytes, the concentrations of tyrosine and cysteine, that is based on the formation of pyrrole-2,3,5-tricarboxylic and their ratio in the medium, are important in determining the concentrations of eumelanin and pheomelanin produced acid and/or aminohydroxyphenylalanine followed by HPLC and their ratio in the cells. In conclusion, our HPLC micro-determination. The method has been applied to the study of melanogenesis. The results summarized in this review are: 1) analytical method for characterizing eumelanin and pheomelanin has become a useful tool for the study of melano-Biochemical studies show that in the process of mixed genesis. melanogenesis, cysteinyldopas are produced first, which are then oxidized to give pheomelanin; following cysteine depletion, eumelanin is then deposited on the preformed pheome-
Synthesis and physiological implications of melanic pigments
The process of melanin synthesis and distribution is called melanogenesis, a process that is based on melanocytes present among the basal cells of the epidermis. Pigments formed in melanocyte melanosomes are then stored in the basal layer of epidermal cells, as well as in dermal macrophages, which become melanophores. From the embryological point of view, melanocytes derive from the melanoblasts of the neural crest, from where they migrate during the first months of life into the skin, eye, cochlea, bone, peripheral nervous system, heart and adipose tissue. The melanic pigments, eumelanin and pheomelanin, are the final product of complex biochemical reactions starting from the amino acid L-tyrosine. Melanin has a major role in skin homeostasis through the photoprotection it offers from the harmful effect of ultraviolet radiation. Melanin absorbs and/or reflects ultraviolet radiation but is also involved in the neutralizing process of free radicals and reactive oxygen species. Pigmentogenesis is a dependent oxygen process and is controlled by intrinsic factors (genetic and hormonal) as well as extrinsic factors (ultraviolet radiation). Melanogenesis is stimulated by stimulant melanocytic hormone, adrenocorticotropin hormone, estrogens and progesterone. The present review aimed to provide a summary of recent data about melanogenesis physiology.
Synthesis and physiological implications of melanic pigments (Review)
Oncology Letters, 2019
The process of melanin synthesis and distribution is called melanogenesis, a process that is based on melanocytes present among the basal cells of the epidermis. Pigments formed in melanocyte melanosomes are then stored in the basal layer of epidermal cells, as well as in dermal macrophages, which become melanophores. From the embryological point of view, melanocytes derive from the melanoblasts of the neural crest, from where they migrate during the first months of life into the skin, eye, cochlea, bone, peripheral nervous system, heart and adipose tissue. The melanic pigments, eumelanin and pheomelanin, are the final product of complex biochemical reactions starting from the amino acid L-tyrosine. Melanin has a major role in skin homeostasis through the photoprotection it offers from the harmful effect of ultraviolet radiation. Melanin absorbs and/or reflects ultraviolet radiation but is also involved in the neutralizing process of free radicals and reactive oxygen species. Pigmentogenesis is a dependent oxygen process and is controlled by intrinsic factors (genetic and hormonal) as well as extrinsic factors (ultraviolet radiation). Melanogenesis is stimulated by stimulant melanocytic hormone, adrenocorticotropin hormone, estrogens and progesterone. The present review aimed to provide a summary of recent data about melanogenesis physiology.
Synthesis and physiological implications of melanic pigments (Review) Stoleriu
ONCOLOGY LETTERS, 2018
The process of melanin synthesis and distribution is called melanogenesis, a process that is based on melanocytes present among the basal cells of the epidermis. Pigments formed in melanocyte melanosomes are then stored in the basal layer of epidermal cells, as well as in dermal macro-phages, which become melanophores. From the embryological point of view, melanocytes derive from the melanoblasts of the neural crest, from where they migrate during the first months of life into the skin, eye, cochlea, bone, peripheral nervous system, heart and adipose tissue. The melanic pigments, eumelanin and pheomelanin, are the final product of complex biochemical reactions starting from the amino acid L-tyrosine. Melanin has a major role in skin homeostasis through the photoprotection it offers from the harmful effect of ultraviolet radiation. Melanin absorbs and/or reflects ultraviolet radiation but is also involved in the neutralizing process of free radicals and reactive oxygen species. Pigmentogenesis is a dependent oxygen process and is controlled by intrinsic factors (genetic and hormonal) as well as extrinsic factors (ultraviolet radiation). Melanogenesis is stimulated by stimulant melanocytic hormone, adrenocorticotropin hormone, estrogens and proges-terone. The present review aimed to provide a summary of recent data about melanogenesis physiology.
A Chemist's View of Melanogenesis
Pigment Cell Research, 2003
The significance of our understanding of the chemistry of melanin and melanogenesis is reviewed. Melanogenesis begins with the production of dopaquinone, a highly reactive o-quinone. Pulse radiolysis is a powerful tool to study the fates of such highly reactive melanin precursors. Based on pulse radiolysis data reported by Land et al. (J Photochem Photobiol B: Biol 2001;64:123) and our biochemical studies, a pathway for mixed melanogenesis is proposed. Melanogenesis proceeds in three distinctive steps. The initial step is the production of cysteinyldopas by the rapid addition of cysteine to dopaquinone, which continues as long as cysteine is present (1 lM). The second step is the oxidation of cysteinyldopas to give pheomelanin, which continues as long as cysteinyldopas are present (10 lM). The last step is the production of eumelanin, which begins only after most cysteinyldopas are depleted. It thus appears that eumelanin is deposited on the preformed pheomelanin and that the ratio of eu-to pheomelanin is determined by the tyrosinase activity and cysteine concentration. In eumelanogenesis, dopachrome is a rather stable molecule and spontaneously decomposes to give mostly 5,6dihydroxyindole. Dopachrome tautomerase (Dct) catalyses the tautomerization of dopachrome to give mostly 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Our study confirmed that the role of Dct is to increase the ratio of DHICA in eumelanin and to increase the production of eumelanin. In addition, the cytotoxicity of o-quinone melanin precursors was found to correlate with binding to proteins through the cysteine residues. Finally, it is still unknown how the availability of cysteine is controlled within the melanosome.
Effect of keratinocytes on regulation of melanogenesis in culture of melanocytes
Biotechnology and Bioprocess Engineering, 2012
Melanocytes are the melanin-producing cells by melanogenesis, and the pigment melanin is primarily responsible for the color of skin. These cells contain dendrites that are in close contact with neighboring keratinocytes. Keratinocytes produce and secrete factors that regulate the proliferation and melanogenesis of melanocytes in vitro. Therefore, adopting only melanocyte pure culture may not clearly reflect the skin physiology in vivo. In this study, we applied a two-culture model using melanocytes and keratinocytes from human skin, such as melanocyte pure culture and melanocyte co-culture with keratinocyte. And then, there was compared the responses of melanocytes under different culture conditions (treatment with arbutin, MSH-α and UV-B irradiation). The results show that there was no significant difference in melanocyte proliferation and melanogenesis between arbutin and MSH-α treatment. However, the co-culture model was more stable than the pure culture model in terms of melanocyte proliferation and melanogenesis upon UV-B irradiation. Therefore, the co-culture model was superior to the pure culture as a useful method for the study of melanocytes and epidermal melanin unit.