Involvement of dynein and spectrin with early melanosome transport and melanosomal protein trafficking.
Melanosomes are unique membrane-bound organelles specialized for the synthesis and distribution of melanin. Mechanisms involved in the trafficking of proteins to melanosomes and in the transport of mature pigmented melanosomes to the dendrites of melanocytic cells are being characterized, but details about those processes during early stages of melanosome maturation are not well understood. Early melanosomes must remain in the perinuclear area until critical components are assembled. In this study, we characterized the processing of two distinct melanosomal proteins, tyrosinase (TYR) and Pmel17, to elucidate protein processing in early or late steps of the secretory pathway, respectively, and to determine mechanisms underlying the subcellular localization and transport of early melanosomes. We used immunological, biochemical, and molecular approaches to demonstrate that the movement of early melanosomes in the perinuclear area depends primarily on microtubules but not on actin filaments. In contrast, the trafficking of TYR and Pmel17 depends on cytoplasmic dynein and its interaction with the spectrin/ankyrin system, which is involved with the sorting of cargo from the plasma membrane. These results provide important clues toward understanding the processes involved with early events in melanosome formation and transport.
Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Hidenori
H
Watabe
Julio C
JC
Valencia
Elodie
E
Le Pape
Yuji
Y
Yamaguchi
Masayuki
M
Nakamura
François
F
Rouzaud
Toshihiko
T
Hoashi
Yoko
Y
Kawa
Masako
M
Mizoguchi
Vincent J
VJ
Hearing
D000199:Actins / Q000502:physiology; D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis; D054366:Agouti Signaling Protein / Q000502:physiology; D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D004295:Dihydroxyphenylalanine / Q000032:analysis; D004398:Dyneins / Q000502:physiology*; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D016547:Kinesins / Q000032:analysis; D008545:Melanoma / Q000378:metabolism; D020460:Melanosomes / Q000502:physiology* / Q000648:ultrastructure; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008854:Microscopy, Electron; D008870:Microtubules / Q000502:physiology; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D021381:Protein Transport; D013049:Spectrin / Q000032:analysis / Q000502:physiology*; D058951:gp100 Melanoma Antigen; D020691:rab GTP-Binding Proteins / Q000032:analysis; D000075745:rab27 GTP-Binding Proteins
C515182:ASIP protein, human; D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D054366:Agouti Signaling Protein; C492410:MLPH protein, human; D008562:Membrane Glycoproteins; C548637:PMEL protein, human; C548642:Pmel protein, mouse; D058951:gp100 Melanoma Antigen; D000075745:rab27 GTP-Binding Proteins; D013049:Spectrin; D004295:Dihydroxyphenylalanine; D014442:Monophenol Monooxygenase; C066694:RAB27A protein, human; D004398:Dyneins; D016547:Kinesins; D020691:rab GTP-Binding Proteins