TNFAIP8: A new effector for Galpha(i) coupling to reduce cell death and induce cell transformation

• Published in: Journal of cellular physiology Vol. 225; no. 3; pp. 865 - 874
• Main Authors: Laliberté, Benoit, Wilson, Ariel M., Nafisi, Houman, Mao, Helen, Zhou, Yi Yuen, Daigle, Mireille, Albert, Paul R.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.12.2010
• Subjects: Amino Acid Sequence; Animals; Apoptosis Regulatory Proteins - genetics; Apoptosis Regulatory Proteins - metabolism; BALB 3T3 Cells; Caspases - metabolism; Cell Death; Cell Transformation, Neoplastic - genetics; Cell Transformation, Neoplastic - metabolism; Cell Transformation, Neoplastic - pathology; Fluorescence Resonance Energy Transfer; GTP-Binding Protein alpha Subunit, Gi2 - metabolism; GTP-Binding Protein alpha Subunits, Gi-Go - genetics; GTP-Binding Protein alpha Subunits, Gi-Go - metabolism; Humans; Immunoprecipitation; Mice; Molecular Sequence Data; NIH 3T3 Cells; Oligonucleotides, Antisense - metabolism; Protein Binding; Protein Interaction Mapping; Receptors, Dopamine D2 - genetics; Receptors, Dopamine D2 - metabolism; Signal Transduction; Transfection; Tumor Necrosis Factor-alpha - metabolism; Two-Hybrid System Techniques
• ISSN: 0021-9541; 1097-4652
• DOI: 10.1002/jcp.22297

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. J. Cell. Physiol. 225: 865–874, 2010. © 2010 Wiley‐Liss, Inc.