title: Effects of genic substitution at the pink-eyed dilution locus on the proliferation and differentiation of mouse epidermal melanocytes in vivo and in vitro.
abstract: Cells positive to the dopa reaction (melanocytes) as well as to the combined dopa-premelanin reaction (melanoblasts and melanocytes) in the epidermis of C57BL/10JHir-p/p (pink-eyed dilution) mice were fewer and less reactive than in C57BL/10JHir (black, P/P) mice, suggesting that the proliferation and differentiation of p/p melanocytes are inhibited. To confirm the inhibitory effects of p gene on the proliferation and differentiation of epidermal melanocytes, we cultured epidermal cell suspensions of neonatal skins from P/P and p/p in a serum-free medium. The proliferation and differentiation of p/p melanoblasts/melanocytes in primary culture were greatly inhibited as compared to P/P melanoblasts/melanocytes. The morphology of p/p melanoblasts/melanocytes cultured in melanocyte growth medium, though non-pigmented, was similar to P/P melanocytes; namely, dendritic, polygonal, or epithelioid. About 8% of p/p cells cultured in melanocyte growth medium were positive to the dopa reaction, and about 25% were reactive to the combined dopa-premelanin reaction. Eumelanin content in p/p was extremely reduced compared to P/P. The immunocytochemical staining of p/p melanoblasts/melanocytes revealed that they are negative to tyrosinase, but reactive to tyrosinase-related protein (TRP)-1, TRP-2, and c-kit. However, the reactivities in p/p were lower than in P/P. Although the differentiation of p/p melanoblasts was not induced by endothelin (ET)-1, ET-2, and ET-3, the proliferation of p/p melanoblasts was stimulated by them. These results suggest for the first time that p gene exerts its influence on the proliferative activities of mouse epidermal melanoblasts by affecting the regulatory mechanisms dependent on the function of ETs.
authors.affiliation: Radiation Hazards Research Group, National Institute of Radiological Sciences, Chiba 263-8555, Japan. thirobe@nirs.go.jp
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Hirobe
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kawa
authors.forename: Masako
authors.initials: M
authors.lastname: Mizoguchi
authors.forename: Shosuke
authors.initials: S
authors.lastname: Ito
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Wakamatsu
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D002352:Carrier Proteins; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000235:genetics* / Q000502:physiology*; D016232:Endothelins / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D008297:Male; D008544:Melanocytes / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D014442:Monophenol Monooxygenase / Q000378:metabolism; D010858:Pigmentation
chemical_list: D002352:Carrier Proteins; D016232:Endothelins; D008565:Membrane Proteins; C076239:P protein, mouse; D014442:Monophenol Monooxygenase