A model of ischemia and reperfusion increases JNK activity, inhibits the association of BAD and 14-3-3, and induces apoptosis of rabbit spinal neurocytes

Abstract

It is now well established that the protein BAD (a pro-apoptotic Bcl-2 family protein) plays a pivotal role in determining cell death and survival. The c-Jun N-terminal kinase (JNK) pathway has been hypothesized to be involved in regulation of BAD. To clarify the role of BAD within the JNK pathway, a randomized, controlled study was designed using a rabbit model of ischemic spinal cord injury [5,8]. Forty-five white adult New England rabbits were randomly assigned to one of the three groups: sham-operation group (n=5), vehicle group (n=20), and JNK inhibitor group (n=20). We examined alterations in spinal tissue morphology, local concentration and cellular locations of key regulatory proteins, and protein-protein interactions. Changes in spinal cord morphology were observed with hematoxylin and eosin (H&E) staining and electron microscopy. In the vehicle group, the amount of JNK phosphorylation, cytochrome c release, and the interaction between BAD and Bcl-XL or Bcl-2 were increased compared with the JNK inhibitor group. Similarly, the phosphorylation of BAD (Ser136) and the interaction between BAD and 14-3-3 were decreased in the vehicle group. Immunohistochemical studies showed that cytoplasmic location of 14-3-3 and p-BAD (Ser136) were decreased in the vehicle group compared with the JNK inhibitor group. In addition, mitochondrial morphology was better preserved and the percentage of apoptosis was lower when JNK was inhibited. These results indicate that the JNK pathway has a critical role in the survival of neurocytes by regulating the interaction between BAD and 14-3-3. © 2010.