The zinc finger domain of NEMO is selectively required for NF-kappa B activation by UV radiation and topoisomerase inhibitors.
Exposure of mammalian cells to UV radiation was proposed to stimulate the transcription factor NF-kappa B by a unique mechanism. Typically, rapid and strong inducers of NF-kappa B, such as tumor necrosis factor alpha (TNF-alpha) and bacterial lipopolysaccharide (LPS), lead to rapid phosphorylation and proteasomal degradation of its inhibitory protein, I kappa B alpha. In contrast, UV, a relatively slower and weaker inducer of NF-kappa B, was suggested not to require phosphorylation of I kappa B alpha for its targeted degradation by the proteasome. We now provide evidence to account for this peculiar degradation process of I kappa B alpha. The phospho-I kappa B alpha generated by UV is only detectable by expressing a Delta F-box mutant of the ubiquitin ligase beta-TrCP, which serves as a specific substrate trap for serine 32 and 36 phosphorylated I kappa B alpha. In agreement with this finding, we also find that the I kappa B kinase (IKK) phospho-acceptor sites on I kappa B alpha, core components of the IKK signalsome, and IKK catalytic activity are all required for UV signaling. Furthermore, deletion and point mutation analyses reveal that both the amino-terminal IKK-binding and the carboxy-terminal putative zinc finger domains of NEMO (IKK gamma) are critical for UV-induced NF-kappa B activation. Interestingly, the zinc finger domain is also required for NF-kappa B activation by two other slow and weak inducers, camptothecin and etoposide. In contrast, the zinc finger module is largely dispensable for NF-kappa B activation by the rapid and strong inducers LPS and TNF-alpha. Thus, we suggest that the zinc finger domain of NEMO likely represents a point of convergence for signaling pathways initiated by slow and weak NF-kappa B-activating conditions.
Huang
Tony T
TT
Program in Molecular and Cellular Pharmacology, Department of Pharmacology, University of Wisconsin-Madison, Madison, Wisconsin 53706-1532, USA.
Feinberg
Shelby L
SL
Suryanarayanan
Sainath
S
Miyamoto
Shigeki
S
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D026942:DNA Topoisomerases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017930:Genes, Reporter; D006801:Humans; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009570:Nitriles; D009930:Organic Chemicals; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D013450:Sulfones; D059003:Topoisomerase Inhibitors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014466:Ultraviolet Rays; D016335:Zinc Fingers; D044844:beta-Transducin Repeat-Containing Proteins
C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; D000970:Antineoplastic Agents; C471644:BTRC protein, human; C471643:Btrc protein, mouse; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; D016328:NF-kappa B; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D009570:Nitriles; D009930:Organic Chemicals; D010750:Phosphoproteins; D013450:Sulfones; D059003:Topoisomerase Inhibitors; D014409:Tumor Necrosis Factor-alpha; D044844:beta-Transducin Repeat-Containing Proteins; D000072000:NF-KappaB Inhibitor alpha; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse; D019204:GTP-Binding Proteins; D026942:DNA Topoisomerases