title: Activation of small GTPases RhoA and Rac1 is required for avian reovirus p10-induced syncytium formation.
abstract: The first ORF of the ARV S1133 S1 segment encodes the nonstructural protein p10, which is responsible for the induction of cell syncytium formation. However, p10-dependent signaling during syncytium formation is fully unknown. Here, we show that dominant negative RhoA, Rho inhibitor C3 exoenzyme, ROCK/Rho-kinase inhibitor Y-27632 and Rac1 inhibitor NSC23766 inhibit p10-mediated cell fusion. p10 over-expression is concomitant with activation and membrane translocation of RhoA and Rac1, but not cdc42. RhoA and Rac1 downstream events, including JNK phosphorylation and transcription factor AP-1 and NF-kappaB activation, as well as MLC expression and phosphorylation are simultaneously activated by p10. p10 point mutant T13M possessed 20% fusion-inducing ability and four p10 fusion-deficient mutants V15M, V19M, C21S and L32A reduced or lost their ability to activate RhoA and Rac1 signaling. We conclude that p10-mediated syncytium formation proceeds by utilizing RhoA and Rac1-dependent signaling.
authors.affiliation: Department of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan.
authors.forename: Hung-Jen
authors.initials: HJ
authors.lastname: Liu
authors.forename: Ping-Yuan
authors.initials: PY
authors.lastname: Lin
authors.forename: Ling-Rung
authors.initials: LR
authors.lastname: Wang
authors.forename: Hsue-Yin
authors.initials: HY
authors.lastname: Hsu
authors.forename: Ming-Huei
authors.initials: MH
authors.lastname: Liao
authors.forename: Wen-Ling
authors.initials: WL
authors.lastname: Shih
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002522:Chlorocebus aethiops; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015726:Giant Cells / Q000187:drug effects / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D030101:Orthoreovirus, Avian / Q000378:metabolism*; D017354:Point Mutation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014709:Vero Cells; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D050505:Mutant Proteins; D016328:NF-kappa B; D018808:Transcription Factor AP-1; D014764:Viral Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein