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 interac...Continue Reading
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