Loss of the cylindromatosis tumour suppressor inhibits apoptosis by activating NF-kappaB.
Protein modification by the conjugation of ubiquitin moieties--ubiquitination--plays a major part in many biological processes, including cell cycle and apoptosis. The enzymes that mediate ubiquitin-conjugation have been well-studied, but much less is known about the ubiquitin-specific proteases that mediate de-ubiquitination of cellular substrates. To study this gene family, we designed a collection of RNA interference vectors to suppress 50 human de-ubiquitinating enzymes, and used these vectors to identify de-ubiquitinating enzymes in cancer-relevant pathways. We report here that inhibition of one of these enzymes, the familial cylindromatosis tumour suppressor gene (CYLD), having no known function, enhances activation of the transcription factor NF-kappaB. We show that CYLD binds to the NEMO (also known as IKKgamma) component of the IkappaB kinase (IKK) complex, and appears to regulate its activity through de-ubiquitination of TRAF2, as TRAF2 ubiquitination can be modulated by CYLD. Inhibition of CYLD increases resistance to apoptosis, suggesting a mechanism through which loss of CYLD contributes to oncogenesis. We show that this effect can be relieved by aspirin derivatives that inhibit NF-kappaB activity, which suggests a therapeutic intervention strategy to restore growth control in patients suffering from familial cylindromatosis.
Brummelkamp
Thijn R
TR
Division of Molecular Carcinogenesis and Center for Biomedical Genetics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
Nijman
Sebastian M B
SM
Dirac
Annette M G
AM
Bernards
René
R
D017209:Apoptosis / Q000187:drug effects; D001241:Aspirin / Q000031:analogs & derivatives / Q000494:pharmacology; D002460:Cell Line; D000074749:Deubiquitinating Enzyme CYLD; D006801:Humans; D051550:I-kappa B Kinase; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D034622:RNA Interference; D047992:TNF Receptor-Associated Factor 2; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism
D016328:NF-kappa B; D011506:Proteins; D047992:TNF Receptor-Associated Factor 2; D014409:Tumor Necrosis Factor-alpha; D025521:Tumor Suppressor Proteins; D025801:Ubiquitin; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C409984:CYLD protein, human; D000074749:Deubiquitinating Enzyme CYLD; D001241:Aspirin