A selective IKK-2 inhibitor blocks NF-kappa B-dependent gene expression in interleukin-1 beta-stimulated synovial fibroblasts.
NF-kappa B-induced gene expression contributes significantly to the pathogenesis of inflammatory diseases such as arthritis. I kappa B kinase (IKK) is the converging point for the activation of NF-kappa B by a broad spectrum of inflammatory agonists and is thus a novel target for therapeutic intervention. We describe a small molecule, selective inhibitor of IKK-2, SC-514, which does not inhibit other IKK isoforms or other serine-threonine and tyrosine kinases. SC-514 inhibits the native IKK complex or recombinant human IKK-1/IKK-2 heterodimer and IKK-2 homodimer similarly. IKK-2 inhibition by SC-514 is selective, reversible, and competitive with ATP. SC-514 inhibits transcription of NF-kappa B-dependent genes in IL-1 beta-induced rheumatoid arthritis-derived synovial fibroblasts in a dose-dependent manner. When the mechanism of NF-kappa B activation was evaluated in the presence of this inhibitor, several interesting observations were found. First, SC-514 did not inhibit the phosphorylation and activation of the IKK complex. Second, there was a delay but not a complete blockade in I kappa B alpha phosphorylation and degradation; likewise there was a slightly slowed, decreased import of p65 into the nucleus and a faster export of p65 from the nucleus. Finally, both I kappa B alpha and p65 were comparable substrates for IKK-2, with similar Km and Kcat values, and SC-514 inhibited the phosphorylation of either substrate similarly. Thus, the effect of SC-514 on cytokine gene expression may be a combination of inhibiting I kappa B alpha phosphorylation/degradation, affecting NF-kappa B nuclear import/export as well as the phosphorylation and transactivation of p65.
Kishore
Nandini
N
Department of Arthritis and Inflammation Pharmacology, Pharmacia Corp., St. Louis, Missouri 63167, USA.
Sommers
Cindy
C
Mathialagan
Sumathy
S
Guzova
Julia
J
Yao
Min
M
Hauser
Scott
S
Huynh
Khai
K
Bonar
Sheri
S
Mielke
Cindy
C
Albee
Lee
L
Weier
Richard
R
Graneto
Matthew
M
Hanau
Cathleen
C
Perry
Thao
T
Tripp
Catherine S
CS
D021581:Active Transport, Cell Nucleus; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000378:metabolism*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D051550:I-kappa B Kinase; D007249:Inflammation; D020128:Inhibitory Concentration 50; D007375:Interleukin-1 / Q000378:metabolism*; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008956:Models, Chemical; D016328:NF-kappa B / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D013583:Synovial Membrane / Q000276:immunology*; D013876:Thiophenes / Q000494:pharmacology*; D013997:Time Factors; D051996:Transcription Factor RelA; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D004791:Enzyme Inhibitors; D007375:Interleukin-1; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011994:Recombinant Proteins; C477523:SC 514; D013876:Thiophenes; D051996:Transcription Factor RelA; D000255:Adenosine Triphosphate; D005982:Glutathione Transferase; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; D010744:Phosphoric Monoester Hydrolases