Protein kinase C zeta isoform is critical for kappa B-dependent promoter activation by sphingomyelinase.
Recent evidence demonstrates that the protein kinase C zeta (zeta PKC) isoform is required for the activation of nuclear factor kappa B (NF-kappa B) and mitogenic signaling in Xenopus oocytes and mammalian cells. The mechanism whereby zeta PKC regulates NF-kappa B most probably involves the activation of a putative I kappa B kinase of molecular mass approximately 50 kDa, which phosphorylates and inactivates I kappa B. Tumor necrosis factor alpha (TNF alpha) and interleukin-1, besides activating the phospholipase C-mediated breakdown of phosphatidylcholine, also generate ceramide, which is produced by stimulation of sphingomyelin hydrolysis. We show here that exogenous addition of sphingomyelinase (SMase) to NIH-3T3 fibroblasts transactivates a kappa B-dependent chloramphenicol acetyltransferase reporter plasmid, to an extent similar to that produced by TNF alpha or phosphatidylcholine/phospholipase C. More importantly, the ability of SMase to stimulate this parameter is severely impaired by transfection of a zeta PKC kinase-defective dominant negative mutant, which suggests a critical role of zeta PKC in SMase signaling. In keeping with this notion, we also demonstrate here that zeta PKC is activated in vitro by ceramide and in vivo by treatment of NIH-3T3 fibroblasts with SMase.
Centro de Biología Molecular Severo Ochoa, Canto Blanco, Madrid, Spain.
J
J
Lozano
E
E
Berra
M M
MM
Municio
M T
MT
Diaz-Meco
I
I
Dominguez
L
L
Sanz
J
J
Moscat
D016475:3T3 Cells; D000818:Animals; D002518:Ceramides / Q000494:pharmacology; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D007527:Isoenzymes / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism*; D051841:Transcription Factor RelB; D014157:Transcription Factors; D015533:Transcriptional Activation; D014162:Transfection; D000099221:Protein Kinase C zeta
D002518:Ceramides; D007527:Isoenzymes; D016328:NF-kappa B; D011493:Protein Kinase C; D011518:Proto-Oncogene Proteins; D013108:Sphingomyelin Phosphodiesterase; D051841:Transcription Factor RelB; D014157:Transcription Factors; D000099221:Protein Kinase C zeta; C497594:Relb protein, mouse; C497595:Relb protein, rat