title: HIV-1 Nef inhibits ruffles, induces filopodia, and modulates migration of infected lymphocytes.
abstract: The HIV-1 Nef protein is a pathogenic factor modulating the behavior of infected cells. Nef induces actin cytoskeleton changes and impairs cell migration toward chemokines. We further characterized the morphology, cytoskeleton dynamics, and motility of HIV-1-infected lymphocytes. By using scanning electron microscopy, confocal immunofluorescence microscopy, and ImageStream technology, which combines flow cytometry and automated imaging, we report that HIV-1 induces a characteristic remodeling of the actin cytoskeleton. In infected lymphocytes, ruffle formation is inhibited, whereas long, thin filopodium-like protrusions are induced. Cells infected with HIV with nef deleted display a normal phenotype, and Nef expression alone, in the absence of other viral proteins, induces morphological changes. We also used an innovative imaging system to immobilize and visualize living individual cells in suspension. When combined with confocal "axial tomography," this technique greatly enhances three-dimensional optical resolution. With this technique, we confirmed the induction of long filopodium-like structures in unfixed Nef-expressing lymphocytes. The cytoskeleton reorganization induced by Nef is associated with an important impairment of cell movements. The adhesion and spreading of infected cells to fibronectin, their spontaneous motility, and their migration toward chemokines (CXCL12, CCL3, and CCL19) were all significantly decreased. Therefore, Nef induces complex effects on the lymphocyte actin cytoskeleton and cellular morphology, which likely impacts the capacity of infected cells to circulate and to encounter and communicate with bystander cells.
authors.affiliation: Virus and Immunity Unit, Department of Virology, Institut Pasteur, URA CNRS 3015, 28 rue du Dr. Roux, Paris Cedex 15, France.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Nobile
authors.forename: Dominika
authors.initials: D
authors.lastname: Rudnicka
authors.forename: Milena
authors.initials: M
authors.lastname: Hasan
authors.forename: Nathalie
authors.initials: N
authors.lastname: Aulner
authors.forename: Françoise
authors.initials: F
authors.lastname: Porrot
authors.forename: Christophe
authors.initials: C
authors.lastname: Machu
authors.forename: Olivier
authors.initials: O
authors.lastname: Renaud
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Prévost
authors.forename: Claire
authors.initials: C
authors.lastname: Hivroz
authors.forename: Olivier
authors.initials: O
authors.lastname: Schwartz
authors.forename: Nathalie
authors.initials: N
authors.lastname: Sol-Foulon
mesh_terms: D002465:Cell Movement / Q000502:physiology*; D048430:Cell Shape; D022081:Cell Surface Extensions / Q000378:metabolism* / Q000648:ultrastructure; D003599:Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D005434:Flow Cytometry / Q000295:instrumentation / Q000379:methods; D015658:HIV Infections / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods; D008214:Lymphocytes / Q000166:cytology* / Q000378:metabolism / Q000821:virology*; D011554:Pseudopodia / Q000378:metabolism* / Q000648:ultrastructure; D054311:nef Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
chemical_list: D054311:nef Gene Products, Human Immunodeficiency Virus; C514837:nef protein, Human immunodeficiency virus 1