Inhibitors of Protein Kinase C (PKC) Prevent Activated Transcription: ROLE OF EVENTS DOWNSTREAM OF NF- Kappa B DNA BINDING

• Published in: The Journal of biological chemistry 2004-04, Vol.279 (18), p.18457-18466
• Main Authors: Catley, M C, Cambridge, L M, Nasuhara, Y, Ito, K, Chivers, JE, Beaton, A, Holden, N S, Bergmann, M W, Barnes, P J, Newton, R
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M400765200

In pulmonary A549 cells, the protein kinase C (PKC) inhibitor, Ro 31-8220, and the phosphotidylcholine-specific phospholipase C inhibitor, D609, prevent NF- Kappa B-dependent transcription, yet NF- Kappa B DNA binding is unaffected (Bergmann, M., Hart, L., Lindsay, M., Barnes, P. J., and Newton, R. (1998) J. Biol. Chem. 273, 6607-6610). We now show that this effect also occurs in BEAS-2B bronchial epithelial cells as well as with other PKC inhibitors (Goe 6976, GF109203X, and calphostin C) in A549 cells. Similarly, phorbol ester, a diacylglycerol mimetic, activates NF- Kappa B-dependent transcription and potentiates tumor necrosis factor alpha (TNF alpha )-induced NF- Kappa B- dependent transcription, yet unlike TNF alpha , poorly activates I Kappa B kinase (IKK) activity, I Kappa B alpha degradation, or NF- Kappa B DNA binding in both A549 and BEAS-2B cells. As phorbol ester-induced NF- Kappa B-dependent transcription was relatively insensitive to the proteasome inhibitor, MG-132, PKC may affect NF- Kappa B-dependent transcription via mechanisms other than the core IKK-I Kappa B pathway. This is supported by Gal4 one hybrid analysis of p65/RelA transactivation, which was potentiated by TNF alpha and phorbol ester and was inhibited by Ro 31-8220 and D609. Additionally, a number of PKC isoforms, particularly the novel isoform PKC epsilon , induced p65/RelA transactivation. Phosphorylation of p65/RelA and cAMP-responsive element-binding protein (CREB)-binding protein (CBP) was increased by TNF alpha treatment and, in the case of CBP, was prevented by Ro 31-8220 or D609. However, p65/RelA-CBP interactions were unaffected by either compound. As this effect was not limited to NF- Kappa B, but was a more general feature of inducible gene transcription, we suggest PKC isoforms may provide a point of intervention in diseases such as inflammation, or cancer, where activated gene expression is prominent.