title: Melanosomes are transferred from melanocytes to keratinocytes through the processes of packaging, release, uptake, and dispersion.
abstract: Recent studies have described the role of shedding vesicles as physiological conveyers of intracellular components between neighboring cells. Here we report that melanosomes are one example of shedding vesicle cargo, but are processed by a previously unreported mechanism. Pigment globules were observed to be connected to the filopodia of melanocyte dendrites, which have previously been shown to be conduits for melanosomes. Pigment globules containing multiple melanosomes were released from various areas of the dendrites of normal human melanocytes derived from darkly pigmented skin. The globules were then captured by the microvilli of normal human keratinocytes, also derived from darkly pigmented skin, which incorporated them in a protease-activated receptor-2 (PAR-2)-dependent manner. After the pigment globules were ingested by the keratinocytes, the membrane that surrounded each melanosome cluster was gradually degraded, and the individual melanosomes then spread into the cytosol and were distributed primarily in the perinuclear area of each keratinocyte. These results suggest a melanosome transfer pathway wherein melanosomes are transferred from melanocytes to keratinocytes via the shedding vesicle system. This packaging system generates pigment globules containing multiple melanosomes in a unique manner.
authors.affiliation: Department of Applied Chemistry and Biotechnology, Okayama University of Science, Okayama, Japan. ando@dac.ous.ac.jp
authors.forename: Hideya
authors.initials: H
authors.lastname: Ando
authors.forename: Yoko
authors.initials: Y
authors.lastname: Niki
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ito
authors.forename: Kaoru
authors.initials: K
authors.lastname: Akiyama
authors.forename: Mary S
authors.initials: MS
authors.lastname: Matsui
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Yarosh
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Ichihashi
mesh_terms: D001692:Biological Transport / Q000502:physiology; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000502:physiology; D002478:Cells, Cultured; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D008544:Melanocytes / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D020460:Melanosomes / Q000502:physiology* / Q000648:ultrastructure; D008871:Microvilli / Q000502:physiology / Q000648:ultrastructure; D010858:Pigmentation / Q000502:physiology; D044464:Receptor, PAR-2 / Q000502:physiology; D022161:Transport Vesicles / Q000502:physiology*
chemical_list: D044464:Receptor, PAR-2