Tumor necrosis factor and interleukin-1 lead to phosphorylation and loss of I kappa B alpha: a mechanism for NF-kappa B activation.
Nuclear factor kappa B (NF-kappa B) is a critical regulator of several genes which are involved in immune and inflammation responses. NF-kappa B, consisting of a 50-kDa protein (p50) and a 65-kDa protein (p65), is bound to a cytoplasmic retention protein called I kappa B. Stimulation of cells with a variety of inducers, including cytokines such as tumor necrosis factor and interleukin-1, leads to the activation and the translocation of p50/65 NF-kappa B into the nucleus. However, the in vivo mechanism of the activation process remains unknown. Here, we provide the first evidence that the in vivo mechanism of NF-kappa B activation is through the phosphorylation and subsequent loss of its inhibitor, I kappa B alpha. We also show that both I kappa B alpha loss and NF-kappa B activation are inhibited in the presence of antioxidants, demonstrating that the loss of I kappa B alpha is a prerequisite for NF-kappa B activation. Finally, we demonstrate that I kappa B alpha is rapidly resynthesized after loss, indicating that an autoregulatory mechanism is involved in the regulation of NF-kappa B function. We propose a mechanism for the activation of NF-kappa B through the modification and loss of I kappa B alpha, thereby establishing its role as a mediator of NF-kappa B activation.
Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill 27599.
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Beg
T S
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Finco
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Nantermet
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Baldwin
D000911:Antibodies, Monoclonal; D000975:Antioxidants / Q000494:pharmacology; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D006367:HeLa Cells; D006706:Homeostasis; D006801:Humans; D020672:I-kappa B Proteins; D007375:Interleukin-1 / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008954:Models, Biological; D016328:NF-kappa B / Q000302:isolation & purification / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D010835:Phytohemagglutinins / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D000911:Antibodies, Monoclonal; D000975:Antioxidants; D004268:DNA-Binding Proteins; C083487:I kappa B beta protein; D020672:I-kappa B Proteins; D007375:Interleukin-1; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010710:Phosphates; D010835:Phytohemagglutinins; D014409:Tumor Necrosis Factor-alpha; D013755:Tetradecanoylphorbol Acetate