Abstract
Death-associated protein (Daxx) deletion mutant (aa 501-625) has been known to be an inducer of apoptosis. In this study, we observed that the Bax-dependent mitochondrial death signaling pathway plays an important role in Daxx501-625-induced apoptosis. Daxx fragment-induced activation of caspase-9 and -3 was mediated through the apoptosis signal-regulating kinase 1 (ASK1)-MEK-c-Jun-N-terminal kinase (JNK)/p38-Bax pathway. By overexpressing JNK-binding domain (JBD) of JIP1, a JNK-inhibitory protein, and treatment with SB203580, a specific p38 inhibitor, DU-145 cells were made resistant to Daxx501-625-induced apoptosis. Capase-3 deficiency, Bax deficiency, or overexpression of a dominant-negative caspase-9 mutant prevented apoptosis, even though the Daxx501-625 fragment still activated the ASK1-MEK-MAPK pathway. Interestingly, Daxx501-625-induced Bcl-2 interacting domain (Bid) cleavage was suppressed in the dominant-negative caspase-9 mutant cells, whereas Bim was still phosphorylated in these cells. These results suggest that cleavage of Bid occurs downstream of caspase-9 activation. In contrast, phosphorylation of Bim is upstream of caspase-9 activation. Taken together, our results suggest that Daxx501-625-induced apoptosis is mediated through the ASK1-MEK-JNK/p38-Bim-Bax-dependent caspase pathway.
Copyright 2004 Wiley-Liss, Inc.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adaptor Proteins, Signal Transducing
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Adenoviridae / genetics
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Apoptosis / physiology*
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Base Sequence
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Carrier Proteins / genetics
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Carrier Proteins / physiology*
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Caspase 9
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Caspases / metabolism
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Cell Line, Tumor
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Co-Repressor Proteins
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Cytochromes c / metabolism
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DNA Primers
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Enzyme Activation
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Genetic Vectors
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Humans
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / physiology*
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JNK Mitogen-Activated Protein Kinases / metabolism*
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MAP Kinase Kinase 4
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Mitochondria / enzymology
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Mitochondria / metabolism*
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Mitogen-Activated Protein Kinase Kinases / metabolism*
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Molecular Chaperones
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Mutation
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Nuclear Proteins / genetics
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Nuclear Proteins / physiology*
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Proto-Oncogene Proteins c-bcl-2 / metabolism*
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Sequence Deletion
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bcl-2-Associated X Protein
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p38 Mitogen-Activated Protein Kinases / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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BAX protein, human
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Carrier Proteins
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Co-Repressor Proteins
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DAXX protein, human
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DNA Primers
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Intracellular Signaling Peptides and Proteins
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Molecular Chaperones
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Nuclear Proteins
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Proto-Oncogene Proteins c-bcl-2
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bcl-2-Associated X Protein
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Cytochromes c
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JNK Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases
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MAP Kinase Kinase 4
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Mitogen-Activated Protein Kinase Kinases
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CASP9 protein, human
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Caspase 9
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Caspases