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Correlation between the number of melanosomes, tyrosinase mrna levels, and tyrosinase activity in cultured murine melanoma cells in response to various melanogenesis regulatory agents
Author(s) -
Ando Hideya,
Itoh Akira,
Mishima Yutaka,
Ichihashi Masamitsu
Publication year - 1995
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041630322
Subject(s) - tyrosinase , melanosome , linoleic acid , melanin , biochemistry , chemistry , biology , enzyme , fatty acid
Tyrosinase is the rate limiting enzyme critically associated with melanin synthesis. The melanosomes are specialized membrane‐bound organelles within melanocytic cells in which melanin polymers are ultimately deposited. To determine whether tyrosinase correlates with the number of melanosomes, we examined the relationship between tyrosinase activity, tyrosinase mRNA levels, and the number of melanosomes in B16 murine melanoma cells, using melanogenesis regulatory agents. 12‐ O ‐Tetradecanoylphorbol‐13‐acetate (TPA) or linoleic acid decreased tyrosinase activity, while dibutyryl cyclic adenosine monophosphate (dbcAMP) or palmitic acid increased it. The tyrosinase mRNA levels were not always correlated with tyrosinase activity, i.e., TPA down‐regulated, dbcAMP upregulated, while linoleic acid or palmitic acid did not alter the message levels, indicating that fatty acid regulation of melanogenesis was due to post‐transcriptional events. The number of melanosomes changed when agents which modulate the tyrosinase gene expression were added, since TPA decreased, dbcAMP increased, and linoleic acid or palmitic acid did not alter their number. These results suggest that the number of melanosomes changed in relation to tyrosinase mRNA level but not to tyrosinase activity in response to melanogenesis regulatory agents. © 1995 Wiley‐Liss, Inc.