The transcription factor NFB is a major regulator of genes involved in inflammation and oncogenesis. NFB is induced upon stimulation of cellular receptors coupled to different intracellular signaling molecules. Further downstream, TRAF6 links at least two receptor pathways to take control of IB, the administrator of NFB activity. Here we report on a strong NFB activation by Tio, a unique herpesviral oncoprotein promoting transformation of human T cells in a Src-kinase-dependent manner. NFB induction by Tio is independent of Src-kinase interaction and tyrosine phosphorylation of Tio. Mutation of a glutamic acid-rich motif at the N terminus of Tio, corresponding to a TRAF6 consensus binding motif, completely abrogated NFB activation. Cotransfection of a dominant negative TRAF6 construct led to a decrease in NFB activation. Furthermore, we provide evidence that TRAF6 directly binds to the Tio oncoprotein. Identification of TRAF6 as the direct target of Tio describes a novel mechanism for the constitutive activation of NFB through an oncoprotein.NFB plays an important role in oncogenesis by promoting genes that have an influence on cell proliferation, cell cycle, differentiation, and apoptosis. It also triggers both innate and adaptive immune responses by transcriptional activation of genes coding for cytokines, chemokines, and adhesion molecules (1, 1-6). Three classical signaling pathways leading to the activation of NFB are initiated by the stimulation of different receptors. Antigen recognition by the T cell receptor induces NFB by recruiting protein tyrosine kinases Lck and Zap70 to the receptor complex. The signal is processed by several intermediate proteins, including protein kinase C (PKC) 2 and a multimolecular module containing CARMA, Bcl-10, MALT1, and TRAF6. Subsequently, the IB kinase (IKK) complex and NFB are activated (5, 7-10). Upon engagement by their cognate ligands, members of the tumor necrosis factor receptor (TNFR) family activate NFB by recruiting TNFR-associated death domain protein (TRADD) and TNFR-associated factor 2 (TRAF2) (11,12). The induction of NFB by the Toll/ interleukin-1 receptor family is a prominent event after stimulation with pro-inflammatory cytokines or recognition of pathogen-associated molecular patterns (13). The signal derived from the prototypic Tolllike receptor-4 is dependent on a module containing myeloid differentiation primary response gene 88 (MYD88) and interleukin-1 receptorassociated kinase-1 (IRAK1). The ubiquitin ligase TRAF6 links this module to a trimolecular complex consisting of transforming growth factor-␤-activated kinase-1 (TAK1), TAK1-binding protein-1 (TAB1), and TAB2 leading to modification of the IKK complex (14, 15).The critical step common to these major NFB-inducing pathways is the activation of the IKK complex. This complex consists of two catalytic subunits, IKK-␣ (IKK1) and IKK-␤ (IKK2), and the regulatory subunit IKK-␥ (NEMO), which is devoid of kinase activity. In the absence of IKK activity, cytoplasmic IB binds NFB and thereby prevents n...

The reactivation of varicella-zoster virus (VZV) from its persistent state in sensory neurones causes shingles and induces severe, long-lasting pain and hyperalgesia that often lead to postherpetic neuralgia. To investigate the VZV-induced neuropathic changes, we established conditions for the active infection of sensory neurones from rat dorsal root ganglia in vitro. After 2 days of culture, up to 50% of the cells expressed viral antigens of the immediate-early and late replication phase. The intracellular calcium ion concentration was monitored in individual cells by microfluorimetry. Whereas the calcium response to capsaicin was preserved, the VZV-infected neurones gained an unusual sensitivity to noradrenaline stimulation in contrast to non-infected cells. The adrenergic agonists phenylephrine and isoproterenol had a similar efficacy demonstrating that both alpha(1)- and beta(1)-adrenoreceptors were involved. The sensitivity to adrenergic stimulation was observed after infection with different wildtype isolates, but not with the attenuated vaccine strain OKA. The lack of noradrenaline sensitivity of vaccine-infected neurones demands a structural comparison of wildtype and vaccine viruses with and without phenotype. A partial sequence evaluation (26 kb) of the European OKA vaccine strain surprisingly revealed a series of nucleotide exchanges in comparison to presumably identical OKA strains from other sources, although VZV is generally considered genetically stable. In summary, we report that the infection with wildtype VZV isolates, but not with the vaccine strain, induces noradrenaline sensitivity in sensory neurones, which correlates with clinical and experimental observations of adrenergic effects involved in VZV-induced neuralgia.

Interferon-gamma (IFN-gamma) is an essential regulator of innate and adaptive immune responses and a hallmark of the Th1 T-cell subset. It is produced at high levels by human T lymphocytes upon transformation with Herpesvirus saimiri, which depends on the expression of the viral oncoproteins saimiri transformation-associated protein of subgroup C (StpC) and tyrosine kinase-interacting protein (Tip). Here, we show that IFN-gamma production was induced by Tip in Jurkat T cells. StpC by itself did not affect IFN-gamma expression, but enhanced the effect of Tip. Our results substantiated the findings that StpC induces NF-kappaB activation and demonstrated that other transcription factors, including NFAT, AP-1 and serum response element regulators, were not activated by StpC in unstimulated T cells. Studies using StpC mutants deficient in NF-kappaB activation, dominant negative IkappaBalpha and constitutively active IKK2, established the importance of NF-kappaB in StpC-mediated upregulation of IFN-gamma production. These observations suggest that NF-kappaB induction by StpC contributes to the Th1-like phenotype of virus-transformed human T cells.