The E3 ubiquitin ligase itch couples JNK activation to TNFalpha-induced cell death by inducing c-FLIP(L) turnover.
The proinflammatory cytokine tumor necrosis factor (TNF) alpha signals both cell survival and death. The biological outcome of TNFalpha treatment is determined by the balance between NF-kappaB and Jun kinase (JNK) signaling; NF-kappaB promotes survival, whereas JNK enhances cell death. Critically, identity of a JNK substrate that promotes TNFalpha-induced apoptosis has been outstanding. Here we show that TNFalpha-mediated JNK activation accelerates turnover of the NF-kappaB-induced antiapoptotic protein c-FLIP, an inhibitor of caspase-8. This is not due to direct c-FLIP phosphorylation but depends on JNK-mediated phosphorylation and activation of the E3 ubiquitin ligase Itch, which specifically ubiquitinates c-FLIP and induces its proteasomal degradation. JNK1 or Itch deficiency or treatment with a JNK inhibitor renders mice resistant in three distinct models of TNFalpha-induced acute liver failure, and cells from these mice do not display inducible c-FLIP(L) ubiquitination and degradation. Thus, JNK antagonizes NF-kappaB during TNFalpha signaling by promoting the proteasomal elimination of c-FLIP(L).
Chang
Lufen
L
Division of Cancer Immunotherapeutics & Tumor Immunology, Beckman Research Institute at City of Hope, City of Hope National Medical Center, 1500 E. Duarte Road, KCRB 3009, Duarte, CA 91010, USA.
Kamata
Hideaki
H
Solinas
Giovanni
G
Luo
Jun-Li
JL
Maeda
Shin
S
Venuprasad
K
K
Liu
Yun-Cai
YC
Karin
Michael
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D004789:Enzyme Activation; D005260:Female; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D017114:Liver Failure, Acute / Q000209:etiology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D008954:Models, Biological; D011247:Pregnancy; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I; D015398:Signal Transduction; D053319:Tumor Necrosis Factor Decoy Receptors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506387:Cflar protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D053319:Tumor Necrosis Factor Decoy Receptors; D014409:Tumor Necrosis Factor-alpha; C069521:recombinant human tumor necrosis factor-binding protein-1; C471637:Itch protein, mouse; D044767:Ubiquitin-Protein Ligases; D048031:JNK Mitogen-Activated Protein Kinases