title: The c-Jun N-terminal protein kinase signaling pathway mediates Bax activation and subsequent neuronal apoptosis through interaction with Bim after transient focal cerebral ischemia.
abstract: The c-Jun N-terminal protein kinase (JNK) signaling pathway is implicated in neuronal apoptosis. The mechanism by which activated JNK induces neuronal apoptosis is strongly linked to mitochondrial apoptogenic proteins, although the molecular machinery downstream of JNK has not been precisely elucidated. Our study examined the relevance of proapoptotic Bcl-2 family members in JNK-mediated apoptosis after transient focal cerebral ischemia (tFCI), which, when induced by 60 min of middle cerebral artery (MCA) occlusion, elevated levels of JNK activity and phospho-JNK in the MCA territory. Phospho-JNK was primarily expressed in neurons and colocalized with terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL)-positive cells. Inhibition of JNK activity by anthra[1,9-cd]pyrazol-6(2H)-one (SP600125), a selective JNK inhibitor, protected neurons from ischemia-induced apoptosis detected by TUNEL staining and an apoptotic-related DNA fragmentation assay. SP600125 blocked translocation of the cell death effector Bax from the cytosol to the mitochondria after tFCI. BimL (Bim long) was induced and phosphorylated parallel to JNK activity. Coimmunoprecipitation studies consistently revealed increased interaction of JNK with BimL, as well as BimL with Bax, after tFCI. SP600125 blocked these interactions at a dose that significantly inhibited JNK-induced neuronal apoptosis. These results suggest that the JNK signaling pathway is involved in ischemia-induced neuronal apoptosis by stimulation, at least in part, of Bax translocation to the mitochondria, in which BimL is likely regulated by JNK as a downstream substrate for transmission of apoptotic signals to Bax.
authors.affiliation: Department of Neurosurgery, Program in Neurosciences, Stanford University School of Medicine, Stanford, California 94305-5487, USA.
authors.forename: Shuzo
authors.initials: S
authors.lastname: Okuno
authors.forename: Atsushi
authors.initials: A
authors.lastname: Saito
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hayashi
authors.forename: Pak H
authors.initials: PH
authors.lastname: Chan
mesh_terms: D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000502:physiology*; D004398:Dyneins / Q000378:metabolism; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System; D008297:Male; D008565:Membrane Proteins / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D020409:Molecular Motor Proteins; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology*; D051028:bcl-2-Associated X Protein
chemical_list: D000873:Anthracenes; D051017:Apoptosis Regulatory Proteins; C494828:Bax protein, rat; D000072224:Bcl-2-Like Protein 11; C000606778:Bcl2l11 protein, rat; D002352:Carrier Proteins; D008565:Membrane Proteins; D020409:Molecular Motor Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; C432165:pyrazolanthrone; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D004398:Dyneins