First insert of tau protein is present in all stages of tau pathology in Alzheimer's disease

A Novel Tau Antibody Detecting the First Amino-Terminal Insert Reveals Conformational Differences Among Tau Isoforms

As human Tau undergoes pathologically relevant post-translational modifications when expressed in yeast, the use of humanized yeast models for the generation of novel Tau monoclonal antibodies has previously been proven to be successful. In this study, human Tau2N4R-ΔK280 purified from yeast was used for the immunization of mice and subsequent selection of high affinity Tau-specific monoclonal antibodies. The characterization of four novel antibodies in different Tau model systems yielded a phosphorylation-dependent antibody (15A10), an antibody directed to the first microtubule-binding repeat domain (16B12), a carboxy-terminal antibody (20G10) and an antibody targeting an epitope on the hinge of the first and second amino-terminal insert (18F12). The latter was found to be conformation-dependent, suggesting structural differences between the Tau splicing isoforms and allowing insight in the roles played by the amino-terminal inserts. As this monoclonal antibody also has the capacity to detect tangle-like structures in different transgenic Tau mice and neurofibrillary tangles in brain sections of patients diagnosed with Alzheimer's disease, we also tested the diagnostic potential of 18F12 in a pilot study and found this monoclonal antibody to have the ability to discriminate Alzheimer's disease patients from control individuals based on increased Tau levels in the cerebrospinal fluid.

First-in-Rat Study of Human Alzheimer's Disease Tau Propagation

One of the key features of misfolded tau in human neurodegenerative disorders is its propagation from one brain area into many others. In the last decade, in vivo tau spreading has been replicated in several mouse transgenic models expressing mutated human tau as well as in normal non-transgenic mice. In this study, we demonstrate for the first time that insoluble tau isolated from human AD brain induces full-blown neurofibrillary pathology in a sporadic rat model of tauopathy expressing non-mutated truncated tau protein. By using specific monoclonal antibodies, we were able to monitor the spreading of tau isolated from human brain directly in the rat hippocampus. We found that exogenous human AD tau was able to spread from the area of injection and induce tau pathology. Interestingly, solubilisation of insoluble AD tau completely abolished the capability of tau protein to induce and spread of neurofibrillary pathology in the rat brain. Our results show that exogenous tau is able to induce and drive neurofibrillary pathology in rat model for human tauopathy in a similar way as it was described in various mouse transgenic models. Rat tau spreading model has many advantages over mouse and other organisms including size and complexity, and thus is highly suitable for identification of pathogenic mechanism of tau spreading.