The Phenotypes And Mechanism Of Late-onset Schizophrenia In REG? Knockout Mice

REG?,also called PA28y,PSME3 or Ki antigen,belongs to the family of 11S proteasome activator,can bind and activate 20S proteasome,which degrades many kinds of substrates in a ubiquitin and ATP-independent manner,involving into different physiological processes.However,the function of REGy in nervous system remains unknown up to now.In this study,several methods,including morphological study,behavior study and molecular biological methods were used in the research on different levels to search the function of REGy in nervous system.Firstly,the brain structure and the expression of different neuron markers between REGy knockout mice and wild type control mice were compared through morphological methods.After validation of the normal brain structure of REGy knockout mice,the mice were tested by several behavior analysis,including locomotion activity,sensorimotor gating,cognition,ability of balance,anxiety and depression-like behavior tests.And 8-month-age REGy knockout mice were found that they had schizophrenia-like behavior.Also further study was taken to search the molecular mechanism on the abnormal behavior of REGy knockout mice.And the result showed that REGy can regulate the protein level and activity of GSK3?,an important contributor to schizophrenia,by degradation and affected the development of the disease of mice.Conclusions as following:1.REGy knockout mice had normal brain structureIt showed that there was no significant difference of brain structure between REGy knockout mice and wild type mice through Nissl staining.REGy can localize with several kinds of neuron markers.And these markers can express normally in REGy knockout mice.2.8-month-age REGy knockout mice had late-onset schizophrenia-like behavior8-month-age REGy knockout mice exhibited increased locomotion and stereotype activity,impaired prepulse inhibition,impairment of working memory and nest-building ability,which were typical symptoms of schizophrenia-like behavior.And the symptom can be relieved by the antipsychotic,Haloperidol.However,they had same performance compared with wild type mice in elevated plus maze,tail suspension,sucrose preference and rotarod test,which showed REGy knockout mice had no anxiety or depression-like behavior and had normal ability on balance.3.8-month-age REGy knockout mice showed increased expression and activity of GSK3? in brain tissue.8-month-age REGy knockout mice showed increased level of GSK3? protein through western blot,decreased ratio of GSK3?-Ser9/GSK3? and increased phosphorylation level of GSK3?-Y216,which showed the increased activity of GSK3?.And the inhibitor of GSK3,SB216763,can recover the prepulse inhibition level of REGy knockout mice.4.REGy can regulate the protein level and activity of GSK3P in a degradation manner.It was proved that REGy can degrade GSK3? in cells and this was dependent on REGy activity and 20S proteasome.And in REGy-knocking down cells,GSK3P was more stable and had higher activity.5.The molecular change of REGy knockout mice was consistent with the onset of diseaseThe behavior study proved that 3-month-age REGy knockout mice had no schizophrenia-like behavior.And there was also no difference of GSK3P protein level between both genotypes of mice of 3months,showing the consistence between the molecular change and the onset of disease.This was maybe caused by the change of 20S proteasome activity dependent on age.