title: Daxx deletion mutant (amino acids 501-625)-induced apoptosis occurs through the JNK/p38-Bax-dependent mitochondrial pathway.
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.
authors.affiliation: Department of Surgery and Pharmacology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Jae J
authors.initials: JJ
authors.lastname: Song
authors.forename: Yong J
authors.initials: YJ
authors.lastname: Lee
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000256:Adenoviridae / Q000235:genetics; D017209:Apoptosis / Q000502:physiology*; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D056970:Co-Repressor Proteins; D045304:Cytochromes c / Q000378:metabolism; D017931:DNA Primers; D004789:Enzyme Activation; D005822:Genetic Vectors; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D048670:MAP Kinase Kinase 4; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D018832:Molecular Chaperones; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D017384:Sequence Deletion; D051028:bcl-2-Associated X Protein; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C494826:BAX protein, human; D002352:Carrier Proteins; D056970:Co-Repressor Proteins; C106985:DAXX protein, human; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D009687:Nuclear Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; C506433:CASP9 protein, human; D053453:Caspase 9; D020169:Caspases