Exocytosis of late endosomes does not directly contribute membrane to the formation of phagocytic cups or pseudopods in Dictyostelium.
Exocytosis of late endocytic compartments in Dictyostelium has mostly been studied by live microscopy. Here we show that this exocytosis is accompanied by a complete fusion of late endosomes with the plasma membrane resulting in the transient formation of membrane microdomains that can be visualized by immunofluorescence in fixed cells. This permitted to demonstrate that fusion of late endocytic compartments with the cell surface does not occur in regions of the plasma membrane engaged in the formation of pseudopods, macropinosomes or phagosomes. Our results propose that exocytosis of late endosomes and actin-driven membrane remodeling are mutually exclusive processes.
Charette
Steve J
SJ
Université de Genève, Centre Médical Universitaire, Département de physiologie cellulaire et métabolisme, 1 rue Michel Servet, CH-1211 Geneva 4, Switzerland. steve.charrette@medecine.unige.ch
Cosson
Pierre
P
D000199:Actins / Q000378:metabolism; D000818:Animals; D004023:Dictyostelium / Q000166:cytology / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology*; D008561:Membrane Fusion / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism* / Q000648:ultrastructure; D015800:Protozoan Proteins / Q000378:metabolism
D000199:Actins; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins