Abstract: Objective To investigate whether conventional protein kinase C (cPKC) II- interacting collapsin response mediator protein-2 (CRMP-2) could provide neuroprotection against cerebral ischemic (I) injuries. Methods Male BALB/c mice were randomly divided into normoxic control (Nor), HPC, Nor+Sham, HPC+Sham, Nor+I and HPC+I groups (n=6 per group). Using our HPC and MCAO mouse models, we applied immunoprecipitation, two-dimensional electrophoresis and mass spectrometry to characterize cPKC II-interacting proteins and combined with SDS-PAGE and Western blot to quantitatively analyze CRMP-2 phosphorylation and degradation levels in the brain of mice after HPC and MCAO. Results Proteomics analysis revealed that the expression levels of 10 cPKC II- interacting proteins changed obviously in cerebral cortex of HPC mice when compared with Nor group. One of these proteins, CRMP-2 protein level increased in particulate fraction and decreased in cytosolic fraction of cerebral cortex of HPC mice. CRMP-2 phosphorylation level in ischemic core (Ic) of cerebral cortex decreased significantly (p<0.05, n=6) as compared with that of Nor+sham group, but CRMP-2 phosphorylation levels in HPC+I group increased significantly compared with that of Nor+I group (p<0.05, n=6). In ischemic cortex, CRMP-2 degradation (proteolysis) was observed as the appearance of 55-ku breakdown products (BDP). However, the CRMP-2 degradation level, BDPs products decreased significantly in penumbra (P) of ischemic cortex from HPC+I group when we compared with that of Nor+I group (p<0.05, n=6). Conclusion CRMP-2 was involved in attenuating the decrease of CRMP-2 phosphorylation in ischemic core and inhibiting its degradation in penumbra of cerebral cortex of mice thereby to lessen the ischemic injuries.

Key words: cPKCbetaII, collapsin response mediator protein-2 (CRMP-2), proteomics, hypoxic preconditioning (HPC), middle cerebral artery occlusion (MCAO)