title: Differential requirement for p56lck in HIV-tat versus TNF-induced cellular responses: effects on NF-kappa B, activator protein-1, c-Jun N-terminal kinase, and apoptosis.
abstract: HIV-tat protein, like TNF, activates a wide variety of cellular responses, including NF-kappa B, AP-1, c-Jun N-terminal kinase (JNK), and apoptosis. Whether HIV-tat transduces these signals through the same mechanism as TNF is not known. In the present study we investigated the role of the T cell-specific tyrosine kinase p56lck in HIV-tat and TNF-mediated cellular responses by comparing the responses of Jurkat T cells with JCaM1 cells, an isogeneic lck-deficient T cell line. Treatment with HIV-tat protein activated NF-kappa B, degraded I kappa B alpha, and induced NF-kappa B-dependent reporter gene expression in a time-dependent manner in Jurkat cells but not in JCaM1 cells, suggesting the critical role of p56lck kinase. These effects were specific to HIV-tat, as activation of NF-kappa B by PMA, LPS, H2O2, and TNF was minimally affected. p56lck was also found to be required for HIV-tat-induced but not TNF-induced AP-1 activation. Similarly, HIV-tat activated the protein kinases JNK and mitogen-activated protein kinase kinase in Jurkat cells but not in JCaM1 cells. HIV-tat also induced cytotoxicity, activated caspases, and reactive oxygen intermediates in Jurkat cells, but not in JCaM1 cells. HIV-tat activated p56lck activity in Jurkat cells. Moreover, the reconstitution of JCaM1 cells with p56lck tyrosine kinase reversed the HIV-tat-induced NF-kappa B activation and cytotoxicity. Overall, our results demonstrate that p56lck plays a critical role in the activation of NF-kappa B, AP-1, JNK, and apoptosis by HIV-tat protein but has minimal or no role in activation of these responses by TNF.
authors.affiliation: Cytokine Research Section, Department of Bioimmunotherapy, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Manna
authors.forename: B B
authors.initials: BB
authors.lastname: Aggarwal
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology; D015696:Gene Products, tat / Q000502:physiology*; D017930:Genes, Reporter / Q000276:immunology; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020672:I-kappa B Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D019169:Jurkat Cells / Q000201:enzymology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D017382:Reactive Oxygen Species / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D004268:DNA-Binding Proteins; D015696:Gene Products, tat; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D017382:Reactive Oxygen Species; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D054322:tat Gene Products, Human Immunodeficiency Virus; D000072000:NF-KappaB Inhibitor alpha; D006861:Hydrogen Peroxide; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D013755:Tetradecanoylphorbol Acetate