Protein kinase C-ζ mediates TNF-α-induced ICAM-1 gene transcription in endothelial cells

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Abstract
We addressed the role of protein kinase C (PKC) isozymes in mediating tumor necrosis factor-α (TNF-α)-induced oxidant generation in endothelial cells, a requirement for nuclear factor-κB (NF-κB) activation and intercellular adhesion molecule-1 (ICAM-1) gene transcription. Depletion of the conventional (c) and novel (n) PKC isozymes following 24 h exposure of human pulmonary artery endothelial (HPAE) cells with the phorbol ester, phorbol 12-myristate 13-acetate (500 nM), failed to prevent TNF-α-induced oxidant generation. In contrast, inhibition of PKC-ζ synthesis by the antisense oligonucleotide prevented the oxidant generation following the TNF-α stimulation. We observed that PKC-ζ also induced the TNF-α-induced NF-κB binding to the ICAM-1 promoter and the resultant ICAM-1 gene transcription. We showed that expression of the dominant negative mutant of PKC-ζ prevented the TNF-α-induced ICAM-1 promoter activity, whereas overexpression of the wild-type PKC-ζ augmented the response. These data imply a critical role for the PKC-ζ isozyme in regulating TNF-α-induced oxidant generation and in signaling the activation of NF-κB and ICAM-1 transcription in endothelial cells.