TI-VAMP/VAMP7 is required for optimal phagocytosis of opsonised particles in macrophages.
Phagocytosis relies on extension of plasmalemmal pseudopods generated by focal actin polymerisation and delivery of membranes from intracellular pools. Here we show that compartments of the late endocytic pathway, bearing the tetanus neurotoxin-insensitive vesicle-associated membrane protein (TI-VAMP/VAMP7), are recruited upon particle binding and undergo exocytosis before phagosome sealing in macrophages during Fc receptor (FcR)-mediated phagocytosis. Expression of the dominant-negative amino-terminal domain of TI-VAMP or depletion of TI-VAMP with small interfering RNAs inhibited phagocytosis mediated by Fc or complement receptors. In addition, inhibition of TI-VAMP activity led to a reduced exocytosis of late endocytic vesicles and this resulted in an early blockade of pseudopod extension, as observed by scanning electron microscopy. Therefore, TI-VAMP defines a new pathway of membrane delivery required for optimal FcR-mediated phagocytosis.
Membrane and Cytoskeleton Dynamics group, UMR144 CNRS-Institut Curie, rue d'Ulm 75248 Paris, France.
Virginie
V
Braun
Vincent
V
Fraisier
Graça
G
Raposo
Ilse
I
Hurbain
Jean-Baptiste
JB
Sibarita
Philippe
P
Chavrier
Thierry
T
Galli
Florence
F
Niedergang
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D011992:Endosomes / Q000378:metabolism / Q000648:ultrastructure; D005089:Exocytosis / Q000502:physiology; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism / Q000648:ultrastructure; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008561:Membrane Fusion / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009895:Opsonin Proteins / Q000378:metabolism*; D010587:Phagocytosis / Q000502:physiology*; D010588:Phagosomes / Q000378:metabolism* / Q000648:ultrastructure; D050683:R-SNARE Proteins; D034741:RNA, Small Interfering / Q000378:metabolism; D011961:Receptors, Fc / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D008565:Membrane Proteins; D009895:Opsonin Proteins; D050683:R-SNARE Proteins; D034741:RNA, Small Interfering; D011961:Receptors, Fc; D011993:Recombinant Fusion Proteins; C121241:VAMP7 protein, human