Differentiation of Murine Melanocyte Precursors Induced by 1,25-Dihydroxyvitamin D3 Is Associated with the Stimulation of Endothelin B Receptor Expression

The effects of 1,25-dihydroxyvitamin D 3 on the differentiation of immature melanocyte precursors were studied. The NCC-/melb4 cell line is an immature melanocyte cell line established from mouse neural crest cells. 1,25-dihydroxyvitamin D 3 inhibited the growth of NCC-/melb4 cells at concentrations higher than 10 -8 M. That growth inhibition was accompanied by the induction of tyrosinase and a change in L-3,4-dihydroxyphenylalanine reactivity from negative to positive. Electron microscopy demonstrated that melanosomes were in more advanced stages after 1,25-dihydroxyvitamin D 3 treatment. In primary cultures of murine neural crest cells, L-3,4-dihydroxyphenylalanine-positive cells were increased after 1,25-dihydroxyvitamin D 3 treatment. These findings indicate that 1,25-dihydroxyvitamin D 3 stimulates the differentiation of immature melanocyte precursors. Moreover, immunostaining and reverse transcription–polymerase chain reaction analysis revealed that endothelin B receptor expression was induced in NCC-/melb4 cells following treatment with 1,25-dihydroxyvitamin D 3 . The induction of endothelin B receptor by 1,25-dihydroxyvitamin D 3 was also demonstrated in neural crest cell primary cultures, but not in mature melanocytes. The expression of microphthalmia-associated transcription factor was induced in NCC-/melb4 cells treated with 1,25-dihydroxyvitamin D 3 and endothelin 3, but not by 1,25-dihydroxyvitamin D 3 alone, suggesting that endothelin 3 may stimulate the expression of the microphthalmia-associated transcription factor gene after binding to the endothelin B receptor induced by 1,25-dihydroxyvitamin D 3 . These findings suggest a regulatory role for vitamin D 3 in melanocyte development and melanogenesis, and may also explain the working mechanism of vitamin D 3 in the treatment of vitiligo.