An evolutionary conserved pathway of nuclear factor-kappaB activation involving caspase-mediated cleavage and N-end rule pathway-mediated degradation of IkappaBalpha.
The Drosophila nuclear factor-kappaB (NF-kappaB)-like transcription factor Relish is activated by an endoproteolytic cleavage step mediated by the Drosophila caspase Dredd. We have examined the contribution of the caspase cascade to NF-kappaB activation via TRAIL, a mammalian tumor necrosis factor family ligand that is a potent activator of caspases. Our results demonstrate that TRAIL activates NF-kappaB in two phases as follows: an early caspase independent phase and a late caspase dependent phase. The late phase of the TRAIL-induced NF-kappaB is critically dependent on caspase 8 and can be blocked by pharmacological and genetic inhibitors of caspase 8 activation, such as benzyloxycarbonyl-VAD-fluoromethyl ketone, benzyloxycarbonyl-IETD-fluoromethyl ketone, and small interfering RNA targeting caspase 8 and FADD. Whereas caspase 3 is required for TRAIL-induced apoptosis, it is not involved in TRAIL-induced NF-kappaB activation. The late phase of TRAIL-induced NF-kappaB activation involves caspase mediated cleavage of IkappaBalpha between Asp(31) and Ser(32) residues to generate an N-terminal truncated fragment that is degraded by the proteasome via the N-end rule pathway. Our results demonstrate that caspases play an evolutionarily conserved role as regulated entry points to the N-end rule pathway and in NF-kappaB activation in mammalian cells.
Rathore
Nisha
N
Hamon Center for Therapeutic Oncology Research, Texas 75390-8593, USA.
Matta
Hittu
H
Chaudhary
Preet M
PM
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology; D053148:Caspase 3; D053178:Caspase 6; D053179:Caspase 7; D053181:Caspase 8; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D019143:Evolution, Molecular; D006367:HeLa Cells; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism*; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D018124:Receptors, Tumor Necrosis Factor; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D000072000:NF-KappaB Inhibitor alpha; C505407:CASP3 protein, human; C505514:CASP6 protein, human; C505520:CASP7 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053178:Caspase 6; D053179:Caspase 7; D053181:Caspase 8; D020169:Caspases