AP-1 and KIF13A coordinate endosomal sorting and positioning during melanosome biogenesis.
Specialized cell types exploit endosomal trafficking to deliver protein cargoes to cell type-specific lysosome-related organelles (LROs), but how endosomes are specified for this function is not known. In this study, we show that the clathrin adaptor AP-1 and the kinesin motor KIF13A together create peripheral recycling endosomal subdomains in melanocytes required for cargo delivery to maturing melanosomes. In cells depleted of AP-1 or KIF13A, a subpopulation of recycling endosomes redistributes to pericentriolar clusters, resulting in sequestration of melanosomal enzymes like Tyrp1 in vacuolar endosomes and consequent inhibition of melanin synthesis and melanosome maturation. Immunocytochemistry, live cell imaging, and electron tomography reveal AP-1- and KIF13A-dependent dynamic close appositions and continuities between peripheral endosomal tubules and melanosomes. Our results reveal that LRO protein sorting is coupled to cell type-specific positioning of endosomes that facilitate endosome-LRO contacts and are required for organelle maturation.
Structure and Membrane Compartments, Centre Nationale de la Recherche Scientifique, UMR 144 Institut Curie, Centre de Recherche, Paris F-75248, France.
Cédric
C
Delevoye
Ilse
I
Hurbain
Danièle
D
Tenza
Jean-Baptiste
JB
Sibarita
Stéphanie
S
Uzan-Gafsou
Hiroshi
H
Ohno
Willie J C
WJ
Geerts
Arie J
AJ
Verkleij
Jean
J
Salamero
Michael S
MS
Marks
Graça
G
Raposo
D002460:Cell Line; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D020460:Melanosomes / Q000378:metabolism* / Q000648:ultrastructure; D008854:Microscopy, Electron; D034741:RNA, Small Interfering / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*
C417670:KIF13A protein, human; D034741:RNA, Small Interfering; D018808:Transcription Factor AP-1; D016547:Kinesins