title: The tetraspanin CD63 regulates ESCRT-independent and -dependent endosomal sorting during melanogenesis.
abstract: Cargo sorting to intraluminal vesicles (ILVs) of multivesicular endosomes is required for lysosome-related organelle (LRO) biogenesis. PMEL-a component of melanocyte LROs (melanosomes)-is sorted to ILVs in an ESCRT-independent manner, where it is proteolytically processed and assembled into functional amyloid fibrils during melanosome maturation. Here we show that the tetraspanin CD63 directly participates in ESCRT-independent sorting of the PMEL luminal domain, but not of traditional ESCRT-dependent cargoes, to ILVs. Inactivating CD63 in cell culture or in mice impairs amyloidogenesis and downstream melanosome morphogenesis. Whereas CD63 is required for normal PMEL luminal domain sorting, the disposal of the remaining PMEL transmembrane fragment requires functional ESCRTs but not CD63. In the absence of CD63, the PMEL luminal domain follows this fragment and is targeted for ESCRT-dependent degradation. Our data thus reveal a tight interplay regulated by CD63 between two distinct endosomal ILV sorting processes for a single cargo during LRO biogenesis.
authors.affiliation: Institut Curie, Centre de Recherche, F-75248 Paris, France. guillaume.van-niel@curie.fr
authors.forename: Guillaume
authors.initials: G
authors.lastname: van Niel
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Charrin
authors.forename: Sabrina
authors.initials: S
authors.lastname: Simoes
authors.forename: Maryse
authors.initials: M
authors.lastname: Romao
authors.forename: Leila
authors.initials: L
authors.lastname: Rochin
authors.forename: Paul
authors.initials: P
authors.lastname: Saftig
authors.forename: Michael S
authors.initials: MS
authors.lastname: Marks
authors.forename: Eric
authors.initials: E
authors.lastname: Rubinstein
authors.forename: Graça
authors.initials: G
authors.lastname: Raposo
mesh_terms: D000682:Amyloid / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008247:Lysosomes / Q000378:metabolism; D008544:Melanocytes / Q000166:cytology* / Q000378:metabolism; D020460:Melanosomes / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D057146:Multivesicular Bodies; D015388:Organelles / Q000378:metabolism; D021381:Protein Transport; D060149:Tetraspanin 30 / Q000502:physiology*
chemical_list: D000682:Amyloid; C554587:Cd63 protein, mouse; D056827:Endosomal Sorting Complexes Required for Transport; D060149:Tetraspanin 30