1988 Fiscal Year Final Research Report Summary
Effect of TPA on the growth and differentiation of cultured human normal melanocyte
| Project/Area Number |
61570495
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Dermatology
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| Research Institution | Sapporo Medical College |
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Principal Investigator |
HORIKOSHI Takashi Sapporo Medical College, Department of Dermatology, Assistant Professor, 医学部, 講師 (40145587)
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| Co-Investigator(Kenkyū-buntansha) |
ONODERA Hideo Sapporo Medical College, Department of Dermatology, Instructor, 医学部, 助手 (10194614)
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| Project Period (FY) |
1986 – 1988
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| Keywords | melanocyte / TPA / C-kinase / OAG / H-7 / tyrosinase / チロシナーゼ / コレラトキシン |
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| Research Abstract |
The role of protein kinase C (Ca-activated, phospholipid-dependent protein kinase) in melanocyte growth and tyrosinase activity was examined using H-7 (1-5-Isoquinolinesulfonyl)-2-methyl piperazine dihydrochloride): potent and selective protein kinase C inhibitor, and OAG (1-olelyl-2-Acetyl glycerol): synthetic glycerol. In normal epidermis in vivo melanocytes undergo little replication. TPA (12-0-tetradecanoyl-phorborl-13-acetate), however, supports the proliferation of normal human melanocytes in culture. Withdrawal of TPA from the culture medium leads to a reduction in the dendritic processes, dilatation of cytoplasm, inhibition of growth and death after 5-7 days. TPA is known to be a protent promoter and has been shown to activate directly protein kinase C. The growth of melanocyte was inhibited by 60 % with addition of H-7 (20muM). Melanocytes incubated for 24 hours with 20 mu/ml of OAG revealed the dilatation of cytoplasm. The aggregation or distruption of dendritic processes wer
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e noted in 72 hours. No living cells were observed after 84 hours. OAG (20um/ml) did not support the growth. The inhibitory effects of OAG for melanocyte growth were reduced by the addition of H-7. Tyrosinase activity was not altered by H-7. Protein phosphorylation of melanocytes was analized in the presence of TPA or OAG, or in the absence of TPA. The phosphorylation of the 28 kd molecular weight protein was reduced when melanocyte were incubated with OAG alone or in the absence of TPA. From these data, it is possible to assume that the low level of protein kinase C in melanocyte is favorable for the proliferation of melanocytes. in order to eleucidate the role of protein kinase c for the growth and differentiation of melanocyte, protein kinase C in melanocytes should be measured directly. however, the number of melanocytes available of this assay is limited. How TPA works on the growth and differentiation of cultured melanocytes will provide a better understanding of melanin biology and the process of the malignant transformation of melanocyte. Less
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