Tubulation of class II MHC compartments is microtubule dependent and involves multiple endolysosomal membrane proteins in primary dendritic cells.
Immature dendritic cells (DCs) capture exogenous Ags in the periphery for eventual processing in endolysosomes. Upon maturation by TLR agonists, DCs deliver peptide-loaded class II MHC molecules from these compartments to the cell surface via long tubular structures (endolysosomal tubules). The nature and rules that govern the movement of these DC compartments are unknown. In this study, we demonstrate that the tubules contain multiple proteins including the class II MHC molecules and LAMP1, a lysosomal resident protein, as well as CD63 and CD82, members of the tetraspanin family. Endolysosomal tubules can be stained with acidotropic dyes, indicating that they are extensions of lysosomes. However, the proper trafficking of class II MHC molecules themselves is not necessary for endolysosomal tubule formation. DCs lacking MyD88 can also form endolysosomal tubules, demonstrating that MyD88-dependent TLR activation is not necessary for the formation of this compartment. Endolysosomal tubules in DCs exhibit dynamic and saltatory movement, including bidirectional travel. Measured velocities are consistent with motor-based movement along microtubules. Indeed, nocodazole causes the collapse of endolysosomal tubules. In addition to its association with microtubules, endolysosomal tubules follow the plus ends of microtubules as visualized in primary DCs expressing end binding protein 1 (EB1)-enhanced GFP.
Vyas
Jatin M
JM
Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.
Kim
You-Me
YM
Artavanis-Tsakonas
Katerina
K
Love
J Christopher
JC
Van der Veen
Annemarthe G
AG
Ploegh
Hidde L
HL
D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000378:metabolism; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D002451:Cell Compartmentation / Q000187:drug effects / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D011992:Endosomes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D051861:Kangai-1 Protein / Q000096:biosynthesis / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D051907:Lysosomal Membrane Proteins / Q000096:biosynthesis / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008870:Microtubules / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D015739:Nocodazole / Q000494:pharmacology; D010980:Platelet Membrane Glycoproteins / Q000096:biosynthesis / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000276:immunology; D060149:Tetraspanin 30; D052118:Lysosomal-Associated Membrane Protein 1
D015703:Antigens, CD; D000949:Histocompatibility Antigens Class II; D051861:Kangai-1 Protein; D008070:Lipopolysaccharides; D051907:Lysosomal Membrane Proteins; D008565:Membrane Proteins; D015739:Nocodazole; D010980:Platelet Membrane Glycoproteins; D060149:Tetraspanin 30; C554586:CD63 protein, human; C554587:Cd63 protein, mouse; C497689:Cd82 antigen, mouse; C052255:Lamp1 protein, mouse; D052118:Lysosomal-Associated Membrane Protein 1