STRONG C-JUN AP-1 IMMUNOREACTIVITY IS RESTRICTED TO APOPTOTIC CELLS FOLLOWING INTRACEREBRAL IBOTENIC ACID INJECTION IN DEVELOPING RATS/

Strong c-Jun immunoreactivity, as revealed with the antibody c-Jun/act ivator protein 1 (AP-1) which is raised against the amino acids 91-105 mapping with the amino terminal domain of mouse c-Jun p39, is observe d in apoptotic cells, but not in necrotic cells, following intracerebr al injection of ibotenic acid in the developing rat brain processed fo r immune histochemistry. Immunostaining occurs in the cytoplasm and de ndrites, thus suggesting impaired nuclear translocation of c-Jun in ap optotic cells. Western blotting of total brain homogenates, using the same antibody, shows a band at p39 which is more marked in treated ani mals than in age-matched controls. In addition, increased c-Jun N-term inal kinase 1 (JNK-1) expression, as revealed on Western blots, is fou nd in rats treated with ibotenic acid when compared with controls. In contrast, apoptotic cells are not stained with antibodies to Jun B and Jun D. These results give further support to previous studies showing strong c-Jun expression in apoptotic cells at determinate stages of d evelopment, and emphasize that intracellular distribution of c-Jun, po ssible post-translational modifications of c-Jun due to phosphorylatio n at specific transactivation sites, and lack of associated Jun B and Jun D expression may differentiate the Jun response in apoptotic cells from other forms of cellular response involving c-Jun which are not a ssociated with cell death. (C) 1997 Elsevier Science Ireland Ltd.