Vanadate facilitates interferon alpha-mediated apoptosis that is dependent on the Jak/Stat pathway.
Type I interferon (IFN)-dependent inhibition of cell growth can occur either in the absence or presence of apoptosis. The mechanisms that determine whether or not cells undergo apoptosis after exposure to IFN-alpha are not clear. This study shows that a variety of cell lines that display growth inhibition but not apoptosis in response to IFN-alpha will undergo programmed cell death when low concentrations of the protein-tyrosine phosphatase inhibitor vanadate are added with IFN-alpha. In contrast, the combination of tumor necrosis factor-alpha with vanadate did not trigger apoptosis in these cells. Caspase-3 activity was detected only in cells exposed to IFN-alpha and vanadate but not to IFN-alpha or vanadate alone. The ability of IFN-alpha and vanadate to induce apoptosis did not require expression of p53 and was blocked by N-acetyl-l-cysteine. Activation of the Jak/Stat pathway and expression of IFN-inducible genes was not altered by incubation of cells with IFN-alpha and vanadate compared with IFN-alpha alone. However, mutant cells lacking Stat1, Stat2, Jak1, or Tyk2, or cells expressing kinase inactive Jak1 or Tyk2 did not undergo apoptosis in the presence of IFN-alpha and vanadate. These results suggest that IFN-alpha stimulation of Stat-dependent genes is necessary, but not sufficient, for this cytokine to induce apoptosis. Another signaling cascade that involves the activity of a protein-tyrosine phosphatase and/or the generation of reactive oxygen species may play an important role in promoting IFN-alpha-induced apoptosis.
Gamero
A M
AM
Department of Immunology, Lerner Research Institute, The Cleveland Clinic Foundation, Ohio 44195, USA.
Larner
A C
AC
D000111:Acetylcysteine / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D016898:Interferon-alpha / Q000378:metabolism*; D053613:Janus Kinase 1; D019169:Jurkat Cells; D009154:Mutation; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; D015398:Signal Transduction; D053634:TYK2 Kinase; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D014638:Vanadates / Q000378:metabolism* / Q000494:pharmacology
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D016898:Interferon-alpha; D011506:Proteins; D017382:Reactive Oxygen Species; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050795:STAT2 Transcription Factor; C494084:STAT2 protein, human; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D016159:Tumor Suppressor Protein p53; D014638:Vanadates; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; D053613:Janus Kinase 1; D053634:TYK2 Kinase; C070139:TYK2 protein, human; D012260:Ribonucleases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D000111:Acetylcysteine