title: Negative regulation of JNK signaling by the tumor suppressor CYLD.
abstract: CYLD is a tumor suppressor that is mutated in familial cylindromatosis, an autosomal dominant predisposition to multiple tumors of the skin appendages. Recent studies suggest that transfected CYLD has deubiquitinating enzyme activity and inhibits the activation of transcription factor NF-kappaB. However, the role of endogenous CYLD in regulating cell signaling remains poorly defined. Here we report a critical role for CYLD in negatively regulating the c-Jun NH(2)-terminal kinase (JNK). CYLD knockdown by RNA interference results in hyper-activation of JNK by diverse immune stimuli, including tumor necrosis factor-alpha, interleukin-1, lipopolysaccharide, and an agonistic anti-CD40 antibody. The JNK-inhibitory function of CYLD appears to be specific for immune receptors because the CYLD knockdown has no significant effect on stress-induced JNK activation. Consistently, CYLD negatively regulates the activation of MKK7, an upstream kinase known to mediate JNK activation by immune stimuli. We further demonstrate that CYLD also negatively regulates IkappaB kinase, although this function of CYLD is seen in a receptor-dependent manner. These findings identify the JNK signaling pathway as a major downstream target of CYLD and suggest a receptor-dependent role of CYLD in regulating the IkappaB kinase pathway.
authors.affiliation: Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
authors.forename: William
authors.initials: W
authors.lastname: Reiley
authors.forename: Minying
authors.initials: M
authors.lastname: Zhang
authors.forename: Shao-Cong
authors.initials: SC
authors.lastname: Sun
mesh_terms: D019013:CD40 Antigens / Q000096:biosynthesis; D002460:Cell Line; D045744:Cell Line, Tumor; D000074749:Deubiquitinating Enzyme CYLD; D015972:Gene Expression Regulation, Neoplastic; D005799:Genes, Dominant; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase; D015151:Immunoblotting; D007375:Interleukin-1 / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism; D048670:MAP Kinase Kinase 4; D048688:MAP Kinase Kinase 7 / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism / Q000502:physiology*; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D019013:CD40 Antigens; D007375:Interleukin-1; D008070:Lipopolysaccharides; D016328:NF-kappa B; D034741:RNA, Small Interfering; 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; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D048688:MAP Kinase Kinase 7; C482569:MAP2K7 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C409984:CYLD protein, human; D000074749:Deubiquitinating Enzyme CYLD