title: TNFAIP8: a new effector for Galpha(i) coupling to reduce cell death and induce cell transformation.
abstract: Galpha(i)-coupled receptors comprise a diverse family of receptors that induce transformation by largely unknown mechanisms. We previously found that the Galpha(i)-coupled dopamine-D2short (D2S) receptor transforms Balb-D2S cells via Gαi3. To identify new Gαi effectors, a yeast two-hybrid screen was done using constitutively active Gαi3-Q204L as bait, and tumor necrosis factor-alpha (TNFα)-induced protein 8 (TNFAIP8, SCC-S2/NDED/GG2-1) was identified. In contrast, TNFAIP8-related TIPE1 and TIPE2 showed a very weak interaction with Gαi3. In yeast mating, in vitro pull-down, co-immunoprecipitation and bioluminescence resonance energy transfer (BRET) assays, TNFAIP8 preferentially interacted with activated Gαi proteins, consistent with direct Gαi-TNFAIP8 coupling. Over-expression or depletion of TNFAIP8 using antisense constructs in Balb-D2S cells did not affect D2S-induced signaling to Gαi-dependent inhibition of cAMP. In contrast, antisense depletion of TNFAIP8 completely inhibited spontaneous and D2S-induced foci formation, consistent with a role for TNFAIP8 in Gαi-dependent transformation. To address possible mechanisms, the effect of D2S signaling via TNFAIP8 on TNFα action was examined. D2S receptor activation inhibited TNFα-induced cell death in Balb-D2S cells, but not in cells depleted of TNFAIP8. However, depletion of TNFAIP8 did not prevent D2S-induced inhibition of TNFα-mediated caspase activation, suggesting that D2S/TNFAIP8-induced protection from TNFα-induced cell death is caspase-independent. The data suggest that Gαi-TNFAIP8-mediated rescue of pre-oncogenic cells enhances progression to oncogenic transformation, providing a selective target to inhibit cellular transformation.
authors.affiliation: Ottawa Hospital Research Institute (Neuroscience), University of Ottawa, Ottawa, ON, Canada.
authors.forename: Benoit
authors.initials: B
authors.lastname: Laliberté
authors.forename: Ariel M
authors.initials: AM
authors.lastname: Wilson
authors.forename: Houman
authors.initials: H
authors.lastname: Nafisi
authors.forename: Helen
authors.initials: H
authors.lastname: Mao
authors.forename: Yi Yuen
authors.initials: YY
authors.lastname: Zhou
authors.forename: Mireille
authors.initials: M
authors.lastname: Daigle
authors.forename: Paul R
authors.initials: PR
authors.lastname: Albert
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D041702:BALB 3T3 Cells; D020169:Caspases / Q000378:metabolism; D016923:Cell Death; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D031541:Fluorescence Resonance Energy Transfer; D051960:GTP-Binding Protein alpha Subunit, Gi2 / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D016376:Oligonucleotides, Antisense / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D051017:Apoptosis Regulatory Proteins; D016376:Oligonucleotides, Antisense; D017448:Receptors, Dopamine D2; C550729:TNFAIP8 protein, mouse; D014409:Tumor Necrosis Factor-alpha; C113776:dopamine D2L receptor; D020169:Caspases; C498819:GNAI3 protein, human; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C498016:Gnai2 protein, mouse; C417708:Gnai3 protein, mouse