TRANSCRIPTION OF MELANOGENESIS ENZYMES IN MELANOCYTES - DEPENDENCE UPON CULTURE CONDITIONS AND COCULTIVATION WITH KERATINOCYTES

Eumelanogenesis of human skin melanocytes requires at least three enzy mes: tyrosinase, TRP 1, and TRP 2. The regulation of these enzymes on transcriptional level was detected in a semiquantitative attempt. The total RNA of melanocytes was reverse-transcripted and followed by a PC R with degenerated primers for all three enzymes. The amplification pr oducts were related to each other densitometrically. We examined five different culture conditions: 1) melanocytes in a popular phorbolester containing F-10-medium, 2) melanocytes in a co-culture medium with EG F, 3) melanocytes in a co-culture medium with high calcium, 4) melanoc ytes co-cultured with keratinocytes in EGF containing co-culture mediu m, and 5) melanocytes co-cultured with keratinocytes in coculture medi um with high calcium. Melanocytes cultured in phorbolester containing F-10-medium featured transcripts of tyrosinase, TRP 1, and TRP 2 in th e ratio 45:45:10. The same results were obtained for melanocytes co-cu ltured with keratinocytes under the two different culture conditions. In melanocytes cultured alone in co-culture media only TRP 1-transcrip ts were present. It is likely that under co-culture conditions a kerat inocyte-derived factor supports the transcription of all three enzymes . For melanocytes in the phorbolester-containing melanocyte medium a p roteinkinase C dependent regulation of transcription seems possible.