The Role Of Autophagy And Rab9in Neurodegeneration Of APPswe/PS1dE9Double Transgenic Mice

ObjectiveTo investigate the role of autophagy and Rab9in neurodeneration of Alzheimer’sdisease by using APPswe/PS1dE9double transgenic mice as model.Methods1．Heterozygous Genotyping of transgenic mice was done by PCR.2．Open field test (OFT) and novel object recognition test(NORT) were performed inAPPswe/PS1dE9double transgenic mice and their age and gender matched wild type (WT)littermates at6months (female, male)and12months (male) of age respectively.3. Immunohistochemical and immunofluorescent labeling were performed on frozensection of APPswe/PS1dE9double transgenic mice and their age and gender matched wildtype (WT) littermates at12months to detect the expression of Aβ116, LC3B,Rab9andVimentin.4. Double fluoresce staining was adopted to display the spatial relationship betweensenile plagues and vimentin positive cells.5. Western blot was employed to detect the expression level of LC3B Ⅰ、LC3B Ⅱ、Rab9and vimentin quantitatively in the brain lysates of APPswe/PS1dE9double transgenicmice and their age and gender matched wild type (wt) littermates at12monthsrespectively. Results1. Compared to their controls, only12month old Tg mice showed hypoactivity andincreased anxiety profile in the OFT (P<0.05). No significant differences between thedouble transgenic mice and its wildtype littermates could be detected in the NORT.2. Abundant typical senile plaques with “densed core” could be detected in the cortexand hippocampus of12months old APPswe/PS1dE9double transgenic mice.3. LC3B was visualized in the perikarya and dendrites of neurons of cortex andhippocampus. Compared to the wt mice, the expression of LC3B and LC3B Ⅱincreasedsignificantly in the brain of APPswe/PS1dE9double transgenic mice at12months of age.(P=0.0005，P<0.0001).4. Granuliform labeled Rab9gathered in perinuclear region of neural cells with a“half moon”morphology. Similar level of Rab9was detected in the double transgenic miceand its wildtype littermates (P>0.05).5、In hippocampus, Vimentin distributed mainly in perikarya and dendrites of neurons.Vimentin positive cells embraced senile plaques could only be observed in the cortex of12months old double transgenic mice but not in the wildtype ones. The number of vimentinlabeled cells significantly decreased in the hippocampus of double transgenic micecompared with that of wildtype ones (P=0.005), accompanied by the prominent decrease ofamount of vimentin in the brain of double transgenic mice (P=0.0289).ConclusionAPPswe/PS1dE9double transgenic mice can preferably recapitulate some clinical andpathological phenotypes of AD patients, and hence provide a valuable tool to explore thepathogenesis and effective therapeutic strategies of AD, The increased autophagy inducton,dysfunction of Rab9and vimentin may be involved in the neurodegeneration of AD.