title: Dynamic partitioning into lipid rafts controls the endo-exocytic cycle of the alphaL/beta2 integrin, LFA-1, during leukocyte chemotaxis.
abstract: Cell migration entails the dynamic redistribution of adhesion receptors from the cell rear toward the cell front, where they form new protrusions and adhesions. This process may involve regulated endo-exocytosis of integrins. Here we show that in primary neutrophils unengaged alphaL/beta2 integrin (LFA-1) is internalized and rapidly recycled upon chemoattractant stimulation via a clathrin-independent, cholesterol-sensitive pathway involving dynamic partitioning into detergent-resistant membranes (DRM). Persistent DRM association is required for recycling of the internalized receptor because 1) >90% of endocytosed LFA-1 is associated with DRM, and a large fraction of the internalized receptor colocalizes intracellularly with markers of DRM and the recycling endocytic compartment; 2) a recycling-defective mutant (alphaL/beta2Y735A) dissociates rapidly from DRM upon being endocytosed and is subsequently diverted into a late endosomal pathway; and 3) a dominant negative Rab11 mutant (Rab11S25N) induces intracellular accumulation of endocytosed alphaL/beta2 and prevents its enrichment in chemoattractant-induced lamellipodia. Notably, chemokine-induced migration of neutrophils over immobilized ICAM-1 is abrogated by cholesterol-sequestering agents. We propose that DRM-associated endocytosis allows efficient retrieval of integrins, as they detach from their ligands, followed by polarized recycling to areas of the plasma membrane, such as lamellipodia, where they establish new adhesive interactions and promote outside-in signaling events.
authors.affiliation: Unit of Leukocyte Biology, Vita-Salute San Raffaele University School of Medicine, DIBIT-Scientific Institute San Raffaele, 20132 Milan, Italy. fabbri.monica@hsr.it
authors.forename: Monica
authors.initials: M
authors.lastname: Fabbri
authors.forename: Silvia
authors.initials: S
authors.lastname: Di Meglio
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Gagliani
authors.forename: Elisa
authors.initials: E
authors.lastname: Consonni
authors.forename: Raffaella
authors.initials: R
authors.lastname: Molteni
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Bender
authors.forename: Carlo
authors.initials: C
authors.lastname: Tacchetti
authors.forename: Ruggero
authors.initials: R
authors.lastname: Pardi
mesh_terms: D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000502:physiology*; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D005089:Exocytosis / Q000502:physiology*; D006801:Humans; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism*; D021962:Membrane Microdomains / Q000502:physiology*; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D021381:Protein Transport; D012016:Reference Values
chemical_list: D016169:Lymphocyte Function-Associated Antigen-1