AAV9 Mediated CIP Prevents Loss Of Neurons And Alleviates Behaviour Changes In P25 Overexpression Model Mice

Background:Cyclin-dependent kinase 5(Cdk5)is essential for regulating mammalian central nervous,including cell survival,transfer,differentiation and synapse formation.Deregulation of Cdk5 APP/PS1 is believed to have some effects on neurodegeneration disease.p25 is a cleavage product of Cyclin-dependent kinase 5 regulatory subunit 1(p35),p25 binds with Cdk5 and leads to its hyperactivity.Cdk5/p25 complex hyper-phosphorylates many substrates of cdk5,which results in the neuro-inflammation and apoptosis of neurons.Cdk5 inhibitory peptide has proved to inhibited the activity of Cdk5/p25 complex.In previous studies,we have demonstrated that Cdk5 inhibitory peptide(CIP),mediated by adeno-associated virus serotype-9(AAV9),can protect neurons from apoptosis and alleviate behavior changes in APP/PS1 Alzheimer’s disease and Parkinson’s disease mouse model.In this study,we used a p25 over overexpression mouse model,which overexpresses p25 in postnatal mice,to evaluate whether AAV9 mediated CIP has the same effects in protecting neurons against the neurotoxicity of p25.Methods:We used Tg(tetO-CDK5R1/GFP)/Tg(Camka-tTA)mouse in our research,which overexpress p25 in the forebrain.The expression of p25 was inhibited for 8 weeks postnatally.At week 8,AAV9-RFP-CIP was admitted via intracerebroventricular injection(ICV).We used Nissl staining,histofluorescence,immunofluorescence,immunohistochemistry,western blot and behavior tests to observe the neurotoxicity of overexpression of p25,and the effects of admitting AAV9-RFP-CIP via intracerebroventricular injection in the transgenic mice model.Results:Our results showed that 1.AAV9-RFP-CIP expressed in the hippocampus via intracerebroventricular injection.The intervention of AAV9-RFP-CIP protected the neurons in hippocampus and alleviated the behavior changes of model mice five weeks after the expression of p25;2.16 weeks after the injection of AAV9-RFP-CIP,it still expressed in the hippocampu and protected neurons from apoptosis.However,it failed to reduce the phosphorylation of Tau and the expression of neuro-imflammation factor.Conclusion:Admitting AAV9-RFP-CIP via intracerebroventricular injection relieved the neurotoxicity of p25,inhibited the over-activity of Cdk5/p25,which prevented the apoptosis of neurons and alleviated the behavior changes in model mice.Cdk5 inhibitory peptide(CIP),mediated by adeno-associated virus serotype-9(AAV9)may be a potential therapy for neurodegeneration diseases.