Study On Aggregation Patterns Of Proteasome In Injured Neurons Induced By Transient Cerebral Ischemia

Objective: To investigate the alteration of proteasome after transientCerebral Ischemia and its significance in the protein degradation dysfunction.Proteasome activity reduction is an important pathological phenomenon,resulting in proteins aggregation and neuronal death in the injured neuronsinduced by transient ischemia. Our previous report showed that the trap ofproteasome in the protein aggregates was a reason to lead to the reduction ofproteasome activity. However, the patterns of proteasome entered into proteinaggregates are not clear. In this study, we used a global ischemia model,Hematoxylin-Eosin staining, differential centrifuge, proteasome activity assay,sucrose gradient density centrifuge, and Western blot analysis to investigatethis problem. Our results show，Neuronal death after global ischemia for20min followed by reperfusion was evaluated via Hematoxylin-Eosin staining.compared with those of sham group, the cortex neurons did no presentmorphologically any alteration at reperfusion. Our resultssuggest thatproteasome activity decreased significantly in the cortex neurons whichsuffered from transient ischemia.we thought that the reduction of proteasomeactivity might be one of the factors initiating protein aggregate formation andaccelerating this process after reperfusion following transient ischemia.Proteasome(26S) Trapped in Protein Aggregates as a Whole Unit24h.thisstudy indicates that20S itself could be trapped by protein aggregates atreperfusion30min, and19S itself could be trapped at reperfusion24h. thereare two aggregation patterns of proteasome after transient ischemia andreperfusion. One is that26S proteasome is trapped by protein aggregates as awhole unit, and the other is that19S or20S is trapped in the protein aggregates, respectively, after26S disassociates.