title: Mouse fibroblast expressing human tyrosinase with DHICA-oxidase activity produces predominantly pheomelanin deposit in lysosome.
abstract: The melanogenic gene-transfected cell system serves as a useful tool for the study of the symphonic relation between melanin synthesis and intracellular organelles such as melanosomes in melanocytes. We constructed melanin-producing mouse fibroblasts by transfection of human tyrosinase cDNA to investigate the intracellular changes caused by tyrosinase expression. DHICA-oxidase (5,6-dihydroxyindole-2-carboxylic acid oxidase) activity without TRP-1 (Tyrosinase Related Protein-1) expression in the cells suggested that human tyrosinase also possesses a DHICA-oxidase activities different from mouse tyrosinase. Electron microscopic observation indicated that melanin-deposit organelles have some lysosomal features. These properties of melanin-deposit organelles in tyrosinase expressing fibroblasts provide one evidence for the hypothesis that melanosome is the specialized lysosome in melanocytes.
authors.affiliation: Mishima Institute for Dermatological Research, Kobe, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kondoh
authors.forename: A
authors.initials: A
authors.lastname: Wilczek
authors.forename: S
authors.initials: S
authors.lastname: Narimizu
authors.forename: Y
authors.initials: Y
authors.lastname: Mishima
mesh_terms: D000818:Animals; D002460:Cell Line; D005347:Fibroblasts / Q000201:enzymology / Q000648:ultrastructure; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*; D008543:Melanins / Q000096:biosynthesis* / Q000378:metabolism; D008562:Membrane Glycoproteins; D051379:Mice; D008809:Mice, Inbred C3H; D008854:Microscopy, Electron; D014442:Monophenol Monooxygenase / Q000235:genetics* / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D011506:Proteins
chemical_list: D006023:Glycoproteins; D008543:Melanins; D008562:Membrane Glycoproteins; D011506:Proteins; C018362:pheomelanin; D010088:Oxidoreductases; C489799:TYRP1 protein, human; C079621:Tyrp1 protein, mouse; C064056:tyrosinase-related protein-1; D014442:Monophenol Monooxygenase