Study Of SHIP2 Inhibitor SHIP2-IN-1 In Improving Cognitive Impairment In Alzheimer’s Disease And Alleviating Dopaminergic Neurodegeneration In Parkinson’s Disease

Objective:Neurodegenerative diseases(NDs),also known as degenerative diseases of the nervous system,are classically characterized by irreversible permanent damage to the structure and function of neurons in the brain and spinal cord,which will gradually deteriorate with the progression of the disease.Eventually it can lead to cognitive dysfunction.Common NDs mainly include Alzheimer’s disease(AD),Parkinson’s disease(PD),etc..The occurrence of these diseases may be related to age and aging.But at present,the pathogenesis of NDs is not completely understood.Currently,researchers believe that NDs may be related to oxidative stress,immune inflammatory response,neurotoxins,and mitochondrial dysfunction.SHIP2 is an enzyme that primarily catalyzes the dephosphorization of inositol 3,4,5-triphosphate(PtdIns(3,4,5)P3,PIP3)to the formation of phosphatidylinositol 3,4-diphosphate(PtdIns(3,4)P2,PIP2).SHIP2 can influence cell growth and development,cell proliferation and apoptosis,and neuronal development and function by regulating the levels of PIP3 and PIP2.The previous research showed that SHIP2 could increase tau hyperphosphorylation by reducing the inhibitory phosphorylation of glycogen synthetase kinase 3β(GSK3β)mediated by Amyloid beta(Aβ)at ser9.These findings suggest that targeting SHIP2 may be an effective treatment strategy for AD.SHIP2-IN-1 is a novel and effective SHIP2 inhibitor developed by researchers.It has good physical and chemical properties,especially high brain permeability,and can easily penetrate the blood-brain barrier.In vitro study has demonstrated that SHIP2-IN-1 can protect neuron from Aβ neurotoxicity.Therefore,in this study,we intend to use 3xTg-AD(APP/TAU/PS1)triple transgenic AD mouse model and PD mouse model constructed by C57BL/6 mice as research objects.The N2a and N2a/APPswe cells are used to verify the results of previous in vitro studies.The effect of SHIP2-IN-1 on the pathological mechanism of AD and PD was examined by morphological,behavioral and molecular biology experiments,and the experimental evidence was provided for SHIP2-IN-1 to be a potential drug for the treatment of AD and PD.Methods:3xTg-AD transgenic mice were used to investigate the effect of SHIP2-IN-1 on the learning and memory abilities of mice,as well as Tau phosphorylation in the cerebral cortex and hippocampus of AD.Meanwhile,1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)was used to induce subacute C57BL/6 mice as PD model to investigate the effect of SHIP2-IN-1 on the neurodegeneration of PD.1.Morris water maze experiment was used to detect behavioral changes of 3xTg-AD mice.2.The level of p-Tau in the cerebral cortex and hippocampus of 3xTg-AD mice was detected by immunohistochemistry.3.Bielschowsky staining was used to detect neurofibrillary tangles(NFTs)in the cerebral cortex and hippocampus of 3xTg-AD mice.4.Western blotting was used to detect the effect and mechanism of SHIP2-IN-1 on amyloid precusor protein(APP)and and its phosphorylation level,as well as Tau phosphorylation in the hippocampus of 3xTg-AD mice.5.Western blotting was used to detect the effect and mechanism of SHIP2-IN-1 on Tau phosphorylation in N2a and N2a/APPswe cells.6.Behavioral changes of PD mice were detected by open field test and traction test.7.Immunohistochemistry was used to detect the effect of SHIP2-IN-1 on dopaminergic neurons in the substantia nigra(SN)of MPTP-induced PD mice.8.Western blotting was used to detect the effect and mechanism of SHIP2-IN-1 on dopaminergic neurons in SN of PD mice.Results:Part Ⅰ.Role of SHIP2-IN-1 in AD:1.SHIP2-IN-1 improved learning and memory impairment in 3xTg-AD mice.2.SHIP2-IN-1 reduced the levels of phosphorylated Tau and NFTs in the hippocampus of 3xTg-AD mice.3.SHIP2-IN-1 had no significant effect on the level of APP and its phosphorylation level in the hippocampus of 3xTg-AD mice.4.SHIP2-IN-1 increased the phosphorylation levels of GSK3β and Akt in the hippocampus of 3xTg-AD mice.5.SHIP2-IN-1 reduces the level of p-Tau(S396)in N2a/APPswe cells.6.SHIP2-IN-1 increases p-GSK3β and p-Akt levels in N2a/APPswe cells.Part Ⅱ.Role of SHIP2-IN-1 in PD:1.SHIP2-IN-1 improves movement disorder in the PD mice.2.SHIP2-IN-1 improved the reduction of dopaminergic neurons in SN in the PD mice.3.SHIP2-IN-1 relieved the decreased expression level of tyrosine hydroxylase(TH)in the SN of MPTP-induced PD mice,but significantly affected the expression level of dopamine transporter(DAT).4.SHIP2-IN-1 increased the levels of p-GSK3β and p-Akt in the SN of PD mice.5.SHIP2-IN-1 had no significant effect on the level of p-JNK in SN of PD mice.Conclusion:1.SHIP2-IN-1 improves learning and memory impairment in 3xTg-AD mice probably by activating the Akt pathway to reduce the levels of p-Tau and NFT in the hippocampus.2.SHIP2-IN-1 reduces p-Tau levels in N2a/APPswe cells probably by activating the Akt pathway.3.SHIP2-IN-1 reduces dopaminergic neurodegeneration in PD mouse models probably through the Akt pathway.These studies provide experimental evidence for SHIP2-IN-1 as a potential drug for the treatment of AD and PD.