Interferon-alpha signaling promotes nucleus-to-cytoplasmic redistribution of p95Vav, and formation of a multisubunit complex involving Vav, Ku80, and Tyk2.
Interferons (IFNs) are a family of hormone-like secretory proteins with multiple phenotypical changes, including gene expression and morphological alterations. Earlier studies have shown that IFN-activated Tyk2 kinase physical associates with p95Vav (Vav), a proto-oncogene gene product expressed in hematopoietic cells. Since Tyk2 is a cytoplasmic kinase and Vav is believed to be localized in the nuclear compartment, here we explored the possibility of Vav redistribution in IFN-alpha-activated cells, using the U266 human myeloma cell line as a model system. Using biochemical assays and in situ confocal microscopy, we demonstrate that IFN-alpha treatment triggers a rapid (10 min) translocation of Vav from the nuclear compartment to the cytoplasm. In addition, we also show the existence of IFN-alpha-induced physical interaction between Vav and Ku80, Ku80, and Tyk2, and among Vav, Ku80, and Tyk2 in the cytoplasmic compartment of IFN-stimulated cells. The observed IFN-alpha-induced association among Vav, Ku80, and Tyk2 was dependent on cellular tyrosine kinase activity. Since recently Vav has been shown to promote the GDP/GTP exchange activity of the cytoskeleton signaling molecule small GTPase Rac1 and activates its downstream signaling, our present findings raise the possibility of involvement of the small GTPase in IFN signaling leading to its biological effects, including cytoskeleton reorganization.
Adam
L
L
University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas, 77030, USA.
Bandyopadhyay
D
D
Kumar
R
R
D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism*; D016895:Culture Media, Serum-Free; D003593:Cytoplasm / Q000378:metabolism; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology*; D000072200:Ku Autoantigen; D009101:Multiple Myeloma; D009685:Nuclear Envelope / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051567:Proto-Oncogene Proteins c-vav; D015398:Signal Transduction; D053634:TYK2 Kinase; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured
D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; D016898:Interferon-alpha; C000715470:MAS1 protein, human; D009687:Nuclear Proteins; D011506:Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; D014157:Transcription Factors; C496618:VAV1 protein, human; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D011505:Protein-Tyrosine Kinases; D053634:TYK2 Kinase; C070139:TYK2 protein, human; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen