title: Tocotrienols enhance melanosome degradation through endosome docking/fusion proteins in B16F10 melanoma cells.
abstract: Vitamin E inhibits tyrosinase activity and acts as a melanogenesis inhibitor in epidermal melanocytes in vitro. However, there is no direct evidence indicating that melanosomes are degraded in lysosomes in the presence of vitamin E. To determine whether vitamin E-induced melanosome disintegration is related to the expression of endosome docking/fusion proteins in B16F10 melanoma cells, electron microscopy, reverse transcription-polymerase chain reaction (RT-PCR), and real-time PCR were used to observe the effects of tocomin (α-tocopherols and α,γ,δ-tocotrienols in palm oil) on B16F10 melanoma cells. Melanosomal integrity was lost in lysosomes of B16F10 melanoma cells when treated with tocomin, indicating that tocomin caused the degradation of melanosomes in the lysosomal compartment. RT-PCR and real-time PCR analysis demonstrated mRNA expression of tyrosinase and the endosome docking/fusion proteins (syntaxin7, Rab7, Vps11, Vps16, Vps33, Vps39, and Vps41). Expression of syntaxin7, Vps16, Vps33, and Vps41 mRNA increased significantly in cells treated with tocomin compared with that in controls. These results indicate that the tocomin-induced degradation of melanosomes in the lysosomal compartment occurs with an increase in endosome docking/fusion proteins (syntaxin7, Vps16, Vps33, and Vps41) in cultured B16F10 melanoma cells.
authors.affiliation: Laboratory of Cell Biology, Ajou University Institute for Medical Sciences, Suwon 443-721, South Korea. sohnsh@ajou.ac.kr.
authors.forename: Bunsoon
authors.initials: B
authors.lastname: Choi
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Heo
authors.forename: Hyuk Jae
authors.initials: HJ
authors.lastname: Kwon
authors.forename: Eun-So
authors.initials: ES
authors.lastname: Lee
authors.forename: Seonghyang
authors.initials: S
authors.lastname: Sohn
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism*; D008545:Melanoma / Q000235:genetics / Q000378:metabolism*; D020460:Melanosomes / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D024508:Tocotrienols / Q000494:pharmacology*; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D050600:SNARE Proteins; C570135:Tocomin; D024508:Tocotrienols; D033921:Vesicular Transport Proteins; D014442:Monophenol Monooxygenase