p38 Mitogen-activated protein kinase regulates Bax translocation in cyanide-induced apoptosis.
Execution of cyanide-induced apoptosis is mediated by release of cytochrome c from mitochondria. To determine how cyanide initiates cytochrome c release, Bax translocation was investigated in primary cultures of cortical neurons. Under nonapoptotic (control) conditions, Bax resided predominantly in the cytoplasm. After 300-microM cyanide treatment for 1 h, Bax translocated to the mitochondria, as shown by immunocytochemical staining and subcellular fractionation; Western blot analysis confirmed "cytosol-to-mitochondria" translocation of Bax. Temporal analysis showed that Bax translocation preceded cytochrome c release from the mitochondria, which was initiated 3 h after cyanide treatment. In double-immunofluorescence labeling for both Bax and cytochrome c, it was observed that cytochrome c was released only in cells showing Bax in mitochondria. The role of p38 mitogen-activated protein (MAP) kinase in Bax translocation was studied. The p38 MAP kinase was activated 30 min after cyanide, and its phosphorylation level of activity began to decrease 3 h later. SB203580, a p38 MAP kinase inhibitor, blocked translocation of Bax to mitochondria, whereas SB202474, a control peptide, had no effect on translocation. Inhibition of p38 MAP kinase by SB203580 blocked all downstream effects of Bax translocation, including cytochrome c release, caspase activation, and internucleosomal DNA fragmentation. These results demonstrated that Bax translocation is critical for cyanide-induced cytochrome c release and that p38 MAP kinase regulates Bax translocation from cytosol to mitochondria.
Shou
Y
Y
Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907-1333, USA.
Li
L
L
Prabhakaran
K
K
Borowitz
J L
JL
Isom
G E
GE
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D045304:Cytochromes c / Q000096:biosynthesis; D003593:Cytoplasm / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D011190:Potassium Cyanide / Q000633:toxicity*; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2; D051381:Rats; D017207:Rats, Sprague-Dawley; D051028:bcl-2-Associated X Protein; D048051:p38 Mitogen-Activated Protein Kinases
C494828:Bax protein, rat; D004791:Enzyme Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020169:Caspases; D011190:Potassium Cyanide