A role of SH-compounds in maturation of melanosomes in cells cultured from nevus Ota.

A role of SH-compounds such as cysteine and glutathione in melanogenesis in dermal melanocytes cultured from Ota's nevus tissue was demonstrated in relation to another substrate, dihydroxyphenylalanine (DOPA). Chemical analysis of eumelanin and pheomelanin was performed in addition to the conventional electron microscopic observation. Supplements of the culture medium with each of these compounds separately for two weeks gave rise to the formation of pre-pheomelanosomes and secondary lysosomes or myelinosome-like inclusions. When DOPA and glutathione were added to the medium together, the maturation of melanosomes was promoted. This was proven by the increase in electron-density of pre-melanosomes observed as well as by the content of pheomelanin and eumelanin. However, mature melanosomes were not formed when each of these chemicals was added to the medium individually for the same periods. The melanosome maturation seemed to occur via a process involving secondary lysosomes or myelinosomes, in which more electron-dense particles accumulated in the presence of both reagents. The pheomelanosomal process was also observed, but typical eumelanosome-related processes were not observed in this culture system.