title: Inhibition of interferon signaling by rabies virus phosphoprotein P: activation-dependent binding of STAT1 and STAT2.
abstract: Rabies virus (RV) phosphoprotein P is an interferon (IFN) antagonist counteracting transcriptional activation of type I IFN (K. Brzózka, S. Finke, and K. K. Conzelmann, J. Virol 79:7673-7681, 2005). We here show that RV P in addition is responsible for preventing IFN-alpha/beta- and IFN-gamma-stimulated JAK-STAT signaling in RV-infected cells by the retention of activated STATs in the cytoplasm. Expression of IFN-stimulated response element- and gamma-activated sequence-controlled genes was severely impaired in cells infected with RV SAD L16 or in cells expressing RV P protein from transfected plasmids. In contrast, a recombinant RV expressing small amounts of P had lost the ability to interfere with JAK-STAT signaling. IFN-mediated tyrosine phosphorylation of STAT1 and STAT2 was not impaired in RV P-expressing cells; rather, a defect in STAT recycling was suggested by distinct accumulation of tyrosine-phosphorylated STATs in cell extracts. In the presence of P, activated STAT1 and STAT2 were unable to accumulate in the nucleus. Notably, STAT1 and STAT2 were coprecipitated with RV P only from extracts of cells previously stimulated with IFN-alpha or IFN-gamma, whereas in nonstimulated cells no association of P with STATs was observed. This conditional, IFN activation-dependent binding of tyrosine-phosphorylated STATs by RV P is unique for a viral IFN antagonist. The 10 C-terminal residues of P are required for counteracting JAK-STAT signaling but not for inhibition of transcriptional activation of IFN-beta, thus demonstrating two independent functions of RV P in counteracting the host's IFN response.
authors.affiliation: Max von Pettenkofer Institute and Gene Center, Feodor Lynen Str. 25, D-81377 Munich, Germany.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Brzózka
authors.forename: Stefan
authors.initials: S
authors.lastname: Finke
authors.forename: Karl-Klaus
authors.initials: KK
authors.lastname: Conzelmann
mesh_terms: D000818:Animals; D002460:Cell Line; D006801:Humans; D016898:Interferon-alpha / Q000037:antagonists & inhibitors*; D007371:Interferon-gamma / Q000037:antagonists & inhibitors*; D053613:Janus Kinase 1; D051379:Mice; D018832:Molecular Chaperones; D010750:Phosphoproteins / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011820:Rabies virus / Q000378:metabolism / Q000472:pathogenicity; D050794:STAT1 Transcription Factor / Q000378:metabolism*; D050795:STAT2 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction; D015533:Transcriptional Activation; D015678:Viral Structural Proteins / Q000378:metabolism*
chemical_list: D016898:Interferon-alpha; D018832:Molecular Chaperones; C103961:P phosphoprotein, Rabies virus; D010750:Phosphoproteins; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; D015678:Viral Structural Proteins; D007371:Interferon-gamma; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; C507905:Jak1 protein, mouse; D053613:Janus Kinase 1