CD14-dependent endotoxin internalization via a macropinocytic pathway

Article Article scientifique Article CD14-dependent endotoxin internalization via a macropinocytic pathway eng 1998 author Poussin Carine Anne 109912 author Foti Michelangelo 0000-0001-7199-4135 28033 author Carpentier Jean-Louis 25558 author Pugin Jérôme 69624 20285-20291 10.1074/jbc.273.32.20285 9685378 0021-9258 Gram-negative bacterial endotoxin (a lipopolysaccharide (LPS)) specifically binds to CD14, a glycosylphosphatidyl inositol (GPI)-anchored surface myeloid glycoprotein. This interaction leads to cell activation, but it also promotes LPS internalization and detoxification. In this work, we investigated the route of LPS and CD14 internalization and the relevance of CD14 GPI anchor in the endocytic pathway. In promonocytic THP-1 cells transfected with a GPI or a chimeric integral form of CD14, we showed by differential buoyancy in sucrose density gradients that these two forms of CD14 were sorted to different plasma membrane subdomains. However, both forms of CD14 associated preferentially with the same surface microfilament-enriched microvilli or ruffles. Electron microscopic studies indicated that CD14 internalized via macropinocytosis, a process resembling that of phagocytosis, different from "classical" receptor-mediated endocytic pathways, such as clathrin-coated pits or caveolae. With cell warming, the CD14-enriched ruffles fused and formed large vesicles. Later, these vacuoles made stacks and condensed into phago-lysosomes. CD14 was specifically associated with all of these structures. Radiolabeled LPS internalization paralleled CD14 internalization. Confocal microscopic studies confirmed the co-localization of LPS and CD14 both at the cell surface and in endosomal compartments. The microfilament-disrupting, macropinocytosis blocking agent cytochalasin D inhibited LPS and CD14 internalization but did not prevent LPS-dependent activation, indicating that these two processes are dissociated. Antigens, CD14/metabolism Cell Line Centrifugation, Density Gradient Coated Pits, Cell-Membrane/physiology Cytochalasin D/pharmacology Endosomes/physiology Endotoxins/metabolism Fluorescent Antibody Technique Glycosylphosphatidylinositols/physiology Kinetics Lipopolysaccharides/metabolism Lysosomes/physiology Membrane Glycoproteins/metabolism Microscopy, Immunoelectron Monocytes/physiology/ultrastructure Phosphorylation Pinocytosis/physiology Recombinant Fusion Proteins/genetics Transfection/genetics Dewey 612 Dewey 617 134 Département de physiologie cellulaire et métabolisme 21C 63 Département d'anesthésiologie, pharmacologie, soins intensifs et urgences 229 false 472 Obésité et syndrome métabolique 803 The Journal of biological chemistry 273 32 4aa8111d-aebc-4395-9a42-9f4684ac82bd Article (Published version) Restricted Poussin et al JBC 1998.pdf 536632 application/pdf restrictedAccess Faculté de médecine / Section de médecine fondamentale / Département de physiologie cellulaire et métabolisme Faculté de médecine / Section de médecine clinique / Département d'anesthésiologie, pharmacologie, soins intensifs et urgences

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CD14-dependent endotoxin internalization via a macropinocytic pathway	The Journal of biological chemistry			1998	413	0

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Poussin, Carine Anne