PIG3V, an immortalized human vitiligo melanocyte cell line, expresses dilated endoplasmic reticulum

Vitiligo is an enigmatic pigmentary disorder of the skin. Factors potential ly involved in the progressive loss of melanocytes from the basal layer of the epidermis include genetically determined aberrancies of the vitiligo me lanocyte. It follows that analysis of melanocytes cultured from vitiligo do nors can contribute to a further understanding of the etiopathomechanism. A setback for vitiligo research has been the limited availability of vitilig o-derived melanocytes. To overcome this limitation, we have generated a vit iligo melanocyte cell line according to a protocol established previously f or the immortalization of normal human melanocytes. Vitiligo melanocytes Ma 9308P4 were transfected with HPV16 E6 and E7 genes using the retroviral. co nstruct LXSN16E6E7. Successful transformants were selected using geneticin and subsequently cloned to ensure genetic homogeneity. The resulting cell l ine PIG3V has undergone more than 100 cell population doublings since its e stablishment as a confluent primary culture, whereas untransfected melanocy tes derived from adult skin senesce after a maximum of 50 population doubli ngs. Cells immortalized by this transfection procedure retain lineage-speci fic characteristics and proliferate significantly faster than parental cell s. In this study, the phenotype of PIG3V resembled melanocytes rather than melanoma cells in culture. Tyrosinase was processed properly and melanosome s remained pigmented. Importantly, ultrastructural characterization of PIG3 V cells revealed dilated endoplasmic reticulum profiles characteristic of v itiligo melanocytes. An explanation for this dilation may be found in the r etention of proteins with molecular weight of 37.5, 47.5, and 56.5 kDa, as determined by gel electrophoresis of microsomal proteins isolated from radi olabeled cells.