Inflammatory stimuli reprogram macrophage phagocytosis to macropinocytosis for the rapid elimination of pathogens.
Following an infectious challenge, macrophages have to be activated in order to allow efficient clearance of infectious pathogens, but how macrophage activation is coupled to increased clearance remains largely unknown. We here describe that inflammatory stimuli induced the reprogramming of the macrophage endocytic machinery from receptor-mediated phagocytosis to macropinocytosis, allowing the rapid transfer of internalized cargo to lysosomes in a receptor-independent manner. Reprogramming occurred through protein kinase C-mediated phosphorylation of the macrophage protein coronin 1, thereby activating phosphoinositol (PI)-3-kinase activity necessary for macropinocytic uptake. Expression of a phosphomimetic form of coronin 1 was sufficient to induce PI3-kinase activation and macropinocytosis even in the absence of inflammatory stimuli. Together these results suggest a hitherto unknown mechanism to regulate the internalization and degradation of infectious material during inflammation.
Biozentrum, University of Basel, Basel, Switzerland.
Somdeb
S
Bosedasgupta
Biozentrum, University of Basel, Basel, Switzerland.
Jean
J
Pieters
D000818:Animals; D004789:Enzyme Activation / Q000235:genetics / Q000276:immunology; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000473:pathology; D008264:Macrophages / Q000276:immunology* / Q000473:pathology; D051379:Mice; D008817:Mice, Mutant Strains; D008840:Microfilament Proteins / Q000235:genetics / Q000276:immunology*; D010587:Phagocytosis / Q000235:genetics / Q000276:immunology*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000276:immunology*; D010873:Pinocytosis / Q000235:genetics / Q000276:immunology*
D008840:Microfilament Proteins; C072061:coronin proteins; D019869:Phosphatidylinositol 3-Kinases