Adenovirus endocytosis requires actin cytoskeleton reorganization mediated by Rho family GTPases.
Adenovirus (Ad) endocytosis via alphav integrins requires activation of the lipid kinase phosphatidylinositol-3-OH kinase (PI3K). Previous studies have linked PI3K activity to both the Ras and Rho signaling cascades, each of which has the capacity to alter the host cell actin cytoskeleton. Ad interaction with cells also stimulates reorganization of cortical actin filaments and the formation of membrane ruffles (lamellipodia). We demonstrate here that members of the Rho family of small GTP binding proteins, Rac and CDC42, act downstream of PI3K to promote Ad endocytosis. Ad internalization was significantly reduced in cells treated with Clostridium difficile toxin B and in cells expressing a dominant-negative Rac or CDC42 but not a H-Ras protein. Viral endocytosis was also inhibited by cytochalasin D as well as by expression of effector domain mutants of Rac or CDC42 that impair cytoskeletal function but not JNK/MAP kinase pathway activation. Thus, Ad endocytosis requires assembly of the actin cytoskeleton, an event initiated by activation of PI3K and, subsequently, Rac and CDC42.
Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA.
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Li
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Stupack
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Bokoch
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Nemerow
D000199:Actins / Q000378:metabolism*; D000258:Adenovirus Infections, Human / Q000209:etiology / Q000378:metabolism / Q000821:virology; D000260:Adenoviruses, Human / Q000472:pathogenicity*; D000730:Androstadienes / Q000494:pharmacology; D001704:Biopolymers / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D000077191:Wortmannin; D020764:cdc42 GTP-Binding Protein; D054462:p21-Activated Kinases; D020703:ras GTPase-Activating Proteins; D020743:rhoB GTP-Binding Protein
D000199:Actins; D000730:Androstadienes; D001704:Biopolymers; D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020690:GTPase-Activating Proteins; D008565:Membrane Proteins; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D000077191:Wortmannin; D020764:cdc42 GTP-Binding Protein; D054462:p21-Activated Kinases; D020703:ras GTPase-Activating Proteins; D020743:rhoB GTP-Binding Protein; C515903:PAK1 protein, human