Involvement of the AP-1 adaptor complex in early steps of phagocytosis and macropinocytosis.
The best described function of the adaptor complex-1 (AP-1) is to participate in the budding of clathrin-coated vesicles from the trans-Golgi network and endosomes. Here, we show that AP-1 is also localized to phagocytic cups in murine macrophages as well as in Dictyostelium amoebae. AP-1 is recruited to phagosomal membranes at this early stage of phagosome formation and rapidly dissociates from maturing phagosomes. To establish the role of AP-1 in phagocytosis, we made used of Dictyostelium mutant cells (apm1(-) cells) disrupted for AP-1 medium chain. In this mutant, phagocytosis drops by 60%, indicating that AP-1 is necessary for efficient phagocytosis. Furthermore, phagocytosis in apm1(-) cells is more affected for large rather than small particles, and cells exhibiting incomplete engulfment are then often observed. This suggests that AP-1 could participate in the extension of the phagocytic cup. Interestingly, macropinocytosis, a process dedicated to fluid-phase endocytosis and related to phagocytosis, is also impaired in apm1(-) cells. In summary, our data suggest a new role of AP-1 at an early stage of phagosome and macropinosome formation.
Lefkir
Yaya
Y
Institut de Biologie et Chimie des Protéines, UMR5086-CNRS/Université Lyon I, IFR 128 BioSciences Lyon-Gerland, 69367 Lyon, France.
Malbouyres
Marilyne
M
Gotthardt
Daniel
D
Ozinsky
Adrian
A
Cornillon
Sophie
S
Bruckert
Franz
F
Aderem
Alan A
AA
Soldati
Thierry
T
Cosson
Pierre
P
Letourneur
François
F
D000818:Animals; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D004023:Dictyostelium / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008855:Microscopy, Electron, Scanning; D009154:Mutation; D010587:Phagocytosis / Q000502:physiology*; D010588:Phagosomes / Q000378:metabolism; D010873:Pinocytosis / Q000502:physiology*; D018808:Transcription Factor AP-1 / Q000378:metabolism*
D018808:Transcription Factor AP-1