IAP suppression of apoptosis involves distinct mechanisms: the TAK1/JNK1 signaling cascade and caspase inhibition.
The antiapoptotic properties of the inhibitor of apoptosis (IAP) family of proteins have been linked to caspase inhibition. We have previously described an alternative mechanism of XIAP inhibition of apoptosis that depends on the selective activation of JNK1. Here we report that two other members of the IAP family, NAIP ... and ML-IAP, both activate JNK1. Expression of catalytically inactive JNK1 blocks NAIP and ML-IAP protection against ICE- and TNF-alpha-induced apoptosis, indicating that JNK1 activation is necessary for the antiapoptotic effect of these proteins. The MAP3 kinase, TAK1, appears to be an essential component of this antiapoptotic pathway since IAP-mediated activation of JNK1, as well as protection against TNF-alpha- and ICE-induced apoptosis, is inhibited when catalytically inactive TAK1 is expressed. In addition, XIAP, NAIP, and JNK1 bind to TAK1. Importantly, expression of catalytically inactive TAK1 did not affect XIAP inhibition of caspase activity. These data suggest that XIAP's antiapoptotic activity is achieved by two separate mechanisms: one requiring TAK1-dependent JNK1 activation and the second involving caspase inhibition.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Apoptosis, Carrier Proteins, Caspase 1, Caspases, Cell Line, Chromosomal Proteins, Non-Histone, Enzyme Activation, HIV Envelope Protein gp120, Humans, Inhibitor of Apoptosis Proteins, Insect Proteins, JNK Mitogen-Activated Protein Kinases, Kidney, MAP Kinase Kinase 4, MAP Kinase Kinase 7, MAP Kinase Kinase Kinases, Microtubule-Associated Proteins, Mitogen-Activated Protein Kinase 8, Mitogen-Activated Protein Kinase Kinases, Mitogen-Activated Protein Kinases, Neoplasm Proteins, Nerve Tissue Proteins, Neuronal Apoptosis-Inhibitory Protein, Protein Binding, Proteins, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-bcl-2, Recombinant Fusion Proteins, Signal Transduction, Transfection, Tumor Necrosis Factor-alpha, X-Linked Inhibitor of Apoptosis Protein, bcl-2-Associated X Protein
Adaptor Proteins, Signal Transducing, Apoptosis, Carrier Proteins, Caspase 1, Caspases, Cell Line, Chromosomal Proteins, Non-Histone, Enzyme Activation, HIV Envelope Protein gp120, Humans, Inhibitor of Apoptosis Proteins, Insect Proteins, JNK Mitogen-Activated Protein Kinases, Kidney, MAP Kinase Kinase 4, MAP Kinase Kinase 7, MAP Kinase Kinase Kinases, Microtubule-Associated Proteins, Mitogen-Activated Protein Kinase 8, Mitogen-Activated Protein Kinase Kinases, Mitogen-Activated Protein Kinases, Neoplasm Proteins, Nerve Tissue Proteins, Neuronal Apoptosis-Inhibitory Protein, Protein Binding, Proteins, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-bcl-2, Recombinant Fusion Proteins, Signal Transduction, Transfection, Tumor Necrosis Factor-alpha, X-Linked Inhibitor of Apoptosis Protein, bcl-2-Associated X Protein
Mol. Cell. Biol.
Date: Mar. 01, 2002
PubMed ID: 11865055
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