Model Research Of Alzheimer’s Disease Induced By Novel Tau Oligomer

Alzheimer’s disease(AD)is an age-related neurodegenerative disease,companying with clinical manifestations of chronic cognitive impairment such as memory impairment,decreased ability to live,and aphasia.The main characteristic pathologies of AD are mainly composed of Aβ plaques formed by extracellular β-amyloid deposition and neurofibrillary tangles aggregated by intracellular Tau protein.Tau protein is an important target for the mechanism study and drug design of AD.Recently,more and more evidence supports that Tau oligomers are the most neurotoxic form.Because of its small molecular weight and fast formation rate,it can spread between neurons rapidly,induce aggregation of normal Tau within the cell,damage synapses and mitochondria,cause neuroinflammation,and accelerate damage to the central nervous system.Due to the rapid extension of the aggregation process of Tau protein,it is difficult to prepare stable Tau oligomers.The current transgenic mouse models could not represent the sporadic AD patients that account for over 95%.This thesis aims to prepare a structurally stable TauK18 oligomer in a simulated brain environment construct novel cellular and mouse models,explore its mechanism of the Tau oligomer.The methods used here included:(1)preparing TauK18 oligomers by mixing animal brain-derived phospholipid vesicles and TauK18 protein,identifying their structures and components through transmission electron microscopy and protein gel electrophoresis,and characterizing their toxicity in 3 cell lines.(2)constructing of AD mouse model by injecting TauK18 oligomers into the mouse brain and identifying its learning memory,spatial memory and anti-anxiety ability by various behavioristics.(3)measuring Tau pathology,synaptic damage,mitochondrial morphology,autophagy,and function in the above cellular and mouse models by immunoblotting,immunofluorescence staining,and Gallys staining.The results of this thesis are as follows:(1)Transmission electron microscopy and Native gel electrophoresis analyses show that the TauK18 oligomers are uniform in size,stable in composition,and able to inhibit the proliferation of cells,causing nerve cells to produce inflammation.(2)Behavioral experiments,tissue sections,immunofluorescence,and western blotting show that mice injected by TauK18 oligomers showed the decrease of learning memory,spatial memory and anxiolytic capacity.Also,the phosphorylated Tau protein levels and neurofibrillary tangles in the cortex are increased while the synaptic-associated proteins are decreased.(3)ATP synthesis levels and the membrane potentials of mitochondria are declined.Meanwhile time,mitochondrial division and fusion and functions are destroyed and mitochondrial autophagy are enhanced in the mouse model.Tau oligomers play a very important role in the occurrence and development of neurodegenerative diseases associated Tau protein.The Tau oligomers which have stable structures and apparent neurotoxicity in this thesis are derived from the brain environment.The construction of cellular and animal models by Tau oligomers are suitable for the research on the mechanisms for AD and Tau protein-related diseases.