Melanogenesis in cultured melanocytes can be substantially influenced by L-tyrosine and L-cysteine

[摘要] We investigated the effect of varying concentration of 1-tyrosine and 1-cysteine in culture medium on melanin production by human skin melanocytes (skin phototype II/III), In addition to the analyses of dopa oxidase activity and total melanin, pheomelanin production in the cells was assessed by high-performance liquid chromatography determinations of pheomelanin degradation products, 3-aminotyrosine and 4-amino-3-hydroxyphenylalanine. As another marker for pheomelanin, melanosomal sulfur was determined by the use of X-ray microanalysis, With varying concentration of both amino acids, profound changes in the pigmentation patterns of the melanocytes were observed. A high concentration of 1-tyrosine (0.2 mM) was always connected with increased pigmentation. In combination with a low 1-cysteine content: we saw an increase in tyrosinase activity and the highest melanin content, At: high concentrations of both I-tyrosine and I-cysteine, the melanocytes showed reduced tyrosinase activity and they produced notably more pheomelanin. In case of the pheomelanin measurements by high-performance liquid chromatography and the sulfur detection with X-ray microanalysis, strongly increased concentrations were found when cells were maintained in high 1-tyrosine medium as compared with those grown with low 1-tyrosine, This was especially true for the combination with low 1-cysteine showing that the l-tyrosine content of the medium strongly influences not only the eumelanin bur also the pheomelanin production in the cultured melanocyte. It can be concluded that variations in;he concentrations of 1-tyrosine and I-cysteine in culture medium can be used to regulate the melanogenetic phenotype under in vitro conditions.

[发布日期] 1997-12-01

[关键词] pheomelanin;X-ray microanalysis