REPIGMENTAION OF VITILIGO AND MELANOCYTE MIGRATION -REGULATING MECHANISMS OF MELANOCYTE MIGRATION IN EPIDERMIAL-FOLLICULAR UNIT-

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We have shown that the inactive melanocytes in the outer root sheath of the human hair follicles (ORS-MCs) are identifiable by anti-premelanosomal antibodies, but not antibodies to tyrosinase, TRP-1 and TRP-2 (J Invest Dermatol, 106 : 28-35,1996). These melanocytes could be cultivated (J derm Sci, 12 : 204,1996). We developed a new technique to cultivate human melanocytes using switching the conCentration of calcium (Pigment Cell Research, 9 : 58-62,1996). Using organ culture technique to cultivate the hairs, we found that ORS-MCs can become activated and DOPA-positive in vitro. In the hairs with activated ORS-MCs, RT-PCR revealed that tyrosinase transcript appeared after activation (Pigment Cell Res, 10 : 429,1997). Next, we found that melanocyte migration is induced by ET-1 via heterotrimeric G protein and phospholipase A2 (PLA2), and by bFGF and LTC4 via tyrosine kinase and PLA2 (J Invest Dermatol, 108 : 573,1997). Ras-transfected melanocyte study revealed that activated ras is involved in the induction of melanocyte migration (J Derm Sci, 15 : 128,1997). Activated ras-transfected melanoma cells have higher potency of migaration than parent cells, and that PLA2 is activated in ras transfected cells (J Invest Dermatol, 109 : 407,1997). The expression of E-cadherin was found to be reduced by UV irradiation (J Invest Dermatol 106 : 1320-1324,1996). We also found that melanoma cells lack either alpha or beta PKC subspecies and beta type PKC plays an important role in pholbor ester stimulation of cell growth (J Cell Physiol 167 : 406-412,1996). We believe that ORS-MCs can be activated by proper stimulants, proliferate, migrate into surrounding epidermis. Our findings will provide a useful information in establishing a new strategy of the treatment for depigmented disorders.