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Cell Growth Differ. 2002 Jan;13(1):13-8.

Tumor necrosis factor alpha (TNF-alpha) activates Jak1/Stat3-Stat5B signaling through TNFR-1 in human B cells.

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Cell Signaling Unit, Department of Biomorphology, School of Medicine, University of Chieti, 66100 Chieti, Italy.


The biological actions of tumor necrosis factor alpha (TNF-alpha) are mediated by two cell surface receptors, TNFR-1 and TNFR-2. These receptors do not display protein tyrosine kinase activity. Nevertheless, an early TNF-induced activation of specific tyrosine kinases has been reported as an important cue to the cellular response to this cytokine. Here we present evidence that TNF-alpha induces the activation of the cytoplasmic Janus tyrosine kinases Jak1 and Tyk2 in both human healthy peripheral and lymphoma B cells. This event was accompanied by the recruitment of a specific set of latent cytosolic transcription factors, Stat3 and Stat5b. Furthermore, Jak1 coprecipitated with TNFR-1 after TNF-alpha treatment. These data suggest that at least in human B cells this cytokine can exert its biological effects through the Jak-Stat signaling pathway and that such signals are initiated through an interaction between TNFR-1 and Jak 1.

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