title: Arf6 and microtubules in adhesion-dependent trafficking of lipid rafts.
abstract: Integrin-mediated adhesion regulates membrane binding sites for Rac1 within lipid rafts. Detachment of cells from the substratum triggers the clearance of rafts from the plasma membrane through caveolin-dependent internalization. The small GTPase Arf6 and microtubules also regulate Rac-dependent cell spreading and migration, but the mechanisms are poorly understood. Here we show that endocytosis of rafts after detachment requires F-actin, followed by microtubule-dependent trafficking to recycling endosomes. When cells are replated on fibronectin, rafts exit from recycling endosomes in an Arf6-dependent manner and return to the plasma membrane along microtubules. Both of these steps are required for the plasma membrane targeting of Rac1 and for its activation. These data therefore define a new membrane raft trafficking pathway that is crucial for anchorage-dependent signalling.
authors.affiliation: Robert M. Beirne Cardiovascular Research Center, Mellon Prostate Cancer Research Institute, University of Virginia, Charlottesville, Virginia 22908, USA.
authors.forename: Nagaraj
authors.initials: N
authors.lastname: Balasubramanian
authors.forename: David W
authors.initials: DW
authors.lastname: Scott
authors.forename: J David
authors.initials: JD
authors.lastname: Castle
authors.forename: James E
authors.initials: JE
authors.lastname: Casanova
authors.forename: Martin Alexander
authors.initials: MA
authors.lastname: Schwartz
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000502:physiology*; D000199:Actins / Q000502:physiology; D000818:Animals; D002448:Cell Adhesion; D048430:Cell Shape; D002478:Cells, Cultured; D004705:Endocytosis; D004721:Endoplasmic Reticulum / Q000502:physiology; D005089:Exocytosis; D005347:Fibroblasts / Q000502:physiology; D005353:Fibronectins / Q000378:metabolism; D006056:Golgi Apparatus / Q000502:physiology; D021962:Membrane Microdomains / Q000502:physiology*; D051379:Mice; D008870:Microtubules / Q000502:physiology*; D020830:rac1 GTP-Binding Protein / Q000502:physiology
chemical_list: D000089982:ADP-Ribosylation Factor 6; D000199:Actins; D005353:Fibronectins; D020727:ADP-Ribosylation Factors; C000715727:Arf6 protein, mouse; D020830:rac1 GTP-Binding Protein