title: HIV-1 Nef triggers macrophage fusion in a p61Hck- and protease-dependent manner.
abstract: Macrophages are a major target of HIV-1 infection. HIV-1-infected macrophages form multinucleated giant cells (MGCs) using poorly elucidated mechanisms. In this study, we show that MGC formation was reduced when human macrophages were infected with nef-deleted HIV-1. Moreover, expression of Nef, an HIV-1 protein required in several aspects of AIDS, was sufficient to trigger the formation of MGCs in RAW264.7 macrophages. Among Nef molecular determinants, myristoylation was dispensable, whereas the polyproline motif was instrumental for this phenomenon. Nef has been shown to activate hematopoietic cell kinase (Hck), a Src tyrosine kinase specifically expressed in phagocytes, through a well-described polyproline-SH3 interaction. Knockdown approaches showed that Hck is involved in Nef-induced MGC formation. Hck is expressed as two isoforms located in distinct subcellular compartments. Although both isoforms were activated by Nef, only p61Hck mediated the effect of Nef on macrophage fusion. This process was abolished in the presence of a p61Hck kinase-dead mutant or when p61Hck was redirected from the lysosome membrane to the cytosol. Finally, lysosomal proteins including vacuolar adenosine triphosphatase and proteases participated in Nef-induced giant macrophage formation. We conclude that Nef participates in HIV-1-induced MGC formation via a p61Hck- and lysosomal enzyme-dependent pathway. This work identifies for the first time actors of HIV-1-induced macrophage fusion, leading to the formation of MGCs commonly found in several organs of AIDS patients.
authors.affiliation: Département Mécanismes Moléculaires des Infections Mycobactériennes, Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5089, France.
authors.forename: Christel
authors.initials: C
authors.lastname: Vérollet
authors.forename: Yan Mei
authors.initials: YM
authors.lastname: Zhang
authors.forename: Véronique
authors.initials: V
authors.lastname: Le Cabec
authors.forename: Julie
authors.initials: J
authors.lastname: Mazzolini
authors.forename: Guillaume
authors.initials: G
authors.lastname: Charrière
authors.forename: Arnaud
authors.initials: A
authors.lastname: Labrousse
authors.forename: Jérôme
authors.initials: J
authors.lastname: Bouchet
authors.forename: Indira
authors.initials: I
authors.lastname: Medina
authors.forename: Erik
authors.initials: E
authors.lastname: Biessen
authors.forename: Florence
authors.initials: F
authors.lastname: Niedergang
authors.forename: Serge
authors.initials: S
authors.lastname: Bénichou
authors.forename: Isabelle
authors.initials: I
authors.lastname: Maridonneau-Parini
mesh_terms: D000818:Animals; D002460:Cell Line; D015693:Gene Products, nef / Q000276:immunology / Q000378:metabolism*; D015726:Giant Cells / Q000276:immunology / Q000378:metabolism / Q000821:virology*; D015658:HIV Infections / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000821:virology*; D051379:Mice; D008856:Microscopy, Fluorescence; D051572:Proto-Oncogene Proteins c-hck / Q000276:immunology / Q000378:metabolism*
chemical_list: D015693:Gene Products, nef; D007527:Isoenzymes; D051572:Proto-Oncogene Proteins c-hck