Tyrosine Phosphorylation of the Tio Oncoprotein Is Essential for Transformation of Primary Human T Cells

Albrecht, Jens; Müller-Fleckenstein, Ingrid; Schmidt, Monika; Fleckenstein, Bernhard; Biesinger, Brigitte

doi:10.1128/jvi.79.16.10507-10513.2005

Cited by 13 publications

(12 citation statements)

References 48 publications

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“…However, as combined mutations of Y127 with CSKH or SH3B were not tested, additional functions of Tip Y127 may have been masked in our analyses. In addition, residues surrounding Tip Y127, as well as the CSKH and SH3B motifs, are well conserved among different herpesvirus saimiri subgroup C isolates (22,28) and, except for the CSKH motif, in herpesvirus ateles (2,3). The implicit selective pressure for all Lck interaction sites points to an essential function in the natural host whose nature remains enigmatic.…”

Section: Discussionmentioning

confidence: 99%

Growth Transformation of Human T Cells by Herpesvirus Saimiri Requires Multiple Tip-Lck Interaction Motifs

Heck

Friedrich

Gack

et al. 2006

J Virol

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Lymphoma induction and T-cell transformation by herpesvirus saimiri strain C488 depends on two viral oncoproteins, StpC and Tip. The major interaction partner of Tip is the protein tyrosine kinase Lck, a key regulator of T-cell activation. The Lck binding domain (LBD) of Tip comprises two interaction motifs, a proline-rich SH3 domain-binding sequence (SH3B) and a region with homology to the C terminus of Src family kinase domains (CSKH). In addition, biophysical binding analyses with purified Lck-SH2 domain suggest the phosphorylated tyrosine residue 127 of Tip (pY127) as a potential third Lck interaction site. Here, we addressed the relevance of the individual binding motifs, SH3B, CSKH, and pY127, for Tip-Lck interaction and for human T-cell transformation. Both motifs within the LBD displayed Lck binding activities and cooperated to achieve a highly efficient interaction, while pY127, the major tyrosine phosphorylation site of Tip, did not enhance Lck binding in T cells. Herpesvirus saimiri strain C488 recombinants lacking one or both LBD motifs of Tip lost their transforming potential on human cord blood lymphocytes. Recombinant virus expressing Tip with a mutation at position Y127 was still able to transform human T lymphocytes but, in contrast to wild-type virus, was strictly dependent on exogenous interleukin-2. Thus, the strong Lck binding mediated by cooperation of both LBD motifs was essential for the transformation of human T cells by herpesvirus saimiri C488. The major tyrosine phosphorylation site Y127 of Tip was particularly required for transformation in the absence of exogenous interleukin-2, suggesting its involvement in cytokine signaling pathways.

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Section: Discussionmentioning

confidence: 99%

Growth Transformation of Human T Cells by Herpesvirus Saimiri Requires Multiple Tip-Lck Interaction Motifs

Heck

Friedrich

Gack

et al. 2006

J Virol

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“…Tip is phosphorylated on two tyrosine residues, creating binding sites for the SH2 domains of STAT3 and Lck, respectively (43)(44)(45). The sole phosphorylation site of Tio, tyrosine residue 136, is essential for the immortalization of primary human T cells (42). A function of Tio related to StpC could not be demonstrated so far.…”

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confidence: 93%

“…The resulting nucleotide sequences were confirmed by automated sequence analysis on an ABI3100 sequencer (Applied Biosystems, Darmstadt, Germany). Tio mutants FYFF, YFYY, and PARG were described previously (42). Expression plasmids for dominant negative IB␣ (IB␣ DN) and constitutively active IKK2 (IKK2 EE) were kindly provided by R. Voll (University Erlangen-Nürnberg, Erlangen, Germany) (47,48).…”

Section: Methodsmentioning

confidence: 99%

“…In previous studies, different analogous functions for Tip and Tio have been reported. They both interact with cellular Src family kinases by binding to their Src homology 3 (SH3) domain (38,40,41) and are phosphorylated on distinct tyrosine residues by the bound kinase (42,43). Tip is phosphorylated on two tyrosine residues, creating binding sites for the SH2 domains of STAT3 and Lck, respectively (43)(44)(45).…”

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confidence: 99%

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NFκB Signaling Is Induced by the Oncoprotein Tio through Direct Interaction with TRAF6

Heinemann

Biesinger

Fleckenstein

et al. 2006

Journal of Biological Chemistry

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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...

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“…However, HVS infections of other species of New World primates result in rapidly progressing fatal T-cell lymphomas and leukemias (13,23). Besides its potent oncogenicity in vivo, HVS can immortalize peripheral blood mononuclear cells of humans, rhesus monkeys, common marmosets, and rabbits to interleukin-2 (IL-2)-independent growth in vitro (1,2,5). Cell lines derived from peripheral blood mononuclear cells of common marmosets by in vitro immortalization with HVS represent a restricted lymphocyte subpopulation that is CD2 ϩ CD8 ϩ CD4 Ϫ CD56 ϩ , indicating that these cells are likely derived from suppressor/cytotoxic T lymphocytes (24).…”

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confidence: 99%

Herpesvirus Saimiri STP-A Oncoprotein Utilizes Src Family Protein Tyrosine Kinase and Tumor Necrosis Factor Receptor-Associated Factors To Elicit Cellular Signal Transduction

García

Kaserman

Chung

et al. 2007

J Virol

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Upon lymphocyte activation, many cellular proteins, including T-cell receptor and B-cell receptor subunits, adaptor proteins, and other effector molecules, are phosphorylated and subsequently involved in the formation of molecular complexes at the site of activation (42). Particularly, the earliest signaling event is the sequential activation of the nonreceptor protein tyrosine kinases (PTKs) of the Src and Syk families. Activated Src family PTKs (SF-PTKs) Lck and Fyn in T lymphocytes subsequently phosphorylate tyrosine residues within a consensus sequence termed the immunoreceptor tyrosine-based activation motif in the cytosolic tails of the T-cell receptor (TCR) subunits. The phosphorylated immunoreceptor tyrosine-based activation motifs of TCR in turn recruit the Syk family PTKs ZAP-70 and Syk through their SH2 domains (31). Together with Lck and Fyn, the ZAP-70 and Syk kinases then promote the phosphorylation of many intracellular signaling molecules, including phospholipase C-␥1, Cbl, Vav, linker for activation of T cells, and SLP-76 (SH2-containing leukocyte protein 76) (10,43,46,48). Phosphorylation of these cellular signaling molecules ultimately induces various cellular events, such as cytoskeletal alteration, intracellular Ca 2ϩ influx, and NF-AT, AP-1, and NF-B transcription factor activation (31,42,46).Another key signal transduction pathway of T and B lymphocytes is mediated by members of the tumor necrosis factor receptor (TNF-R) and Toll-like receptor family. The key components of these receptor signaling pathways are the cytoplasmic adapter proteins known as TNF-R-associated factors (TRAFs) (8, 55). For example, CD40, a member of the TNF-R family, is expressed on antigen-presenting cells and provides key activation signals in T-cell-dependent B-cell activation by using TRAF signal transduction pathways (44). Several proteins carried by microbes also induce TRAF-mediated signaling pathways. A notable example is the latent membrane protein 1 (LMP-1) produced by the Epstein-Barr virus (EBV) (33). The TRAF proteins are characterized by the presence of a unique TRAF domain at the C terminus, which consists of a coiled-coil domain followed by a conserved TRAF-C domain. The TRAF domain plays an important role in TRAF function by mediating self-association and interaction with upstream receptors and other signaling proteins (8). The N-terminal portions of most TRAF proteins contain a RING finger and several zinc finger motifs, which are important for downstream signaling events. Many of the biological effects of TRAF signaling appear to be mediated through the activation of the NF-B transcription factor (4, 55).Herpesvirus saimiri (HVS) is a member of the gammaherpesvirus family, which includes human EBV and human herpesvirus 8, also called Kaposi's sarcoma-associated herpesvirus. HVS infection is endemic and nonpathogenic in its natural host, squirrel monkeys (Saimiri sciureus) (15). However, HVS infections of other species of New World primates result in rapidly progressing fatal T-cell lymphomas and l...

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Tyrosine Phosphorylation of the Tio Oncoprotein Is Essential for Transformation of Primary Human T Cells

Cited by 13 publications

References 48 publications

Growth Transformation of Human T Cells by Herpesvirus Saimiri Requires Multiple Tip-Lck Interaction Motifs

Growth Transformation of Human T Cells by Herpesvirus Saimiri Requires Multiple Tip-Lck Interaction Motifs

NFκB Signaling Is Induced by the Oncoprotein Tio through Direct Interaction with TRAF6

Herpesvirus Saimiri STP-A Oncoprotein Utilizes Src Family Protein Tyrosine Kinase and Tumor Necrosis Factor Receptor-Associated Factors To Elicit Cellular Signal Transduction

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