Assessment of Alzheimer’s disease (AD)-related neurofibrillary pathology requires a procedure that permits a sufficient differentiation between initial, intermediate, and late stages. The gradual deposition of a hyperphosphorylated tau protein within select neuronal types in specific nuclei or areas is central to the disease process. The staging of AD-related neurofibrillary pathology originally described in 1991 was performed on unconventionally thick sections (100 μm) using a modern silver technique and reflected the progress of the disease process based chiefly on the topographic expansion of the lesions. To better meet the demands of routine laboratories this procedure is revised here by adapting tissue selection and processing to the needs of paraffin-embedded sections (5–15 μm) and by introducing a robust immunoreaction (AT8) for hyperphosphorylated tau protein that can be processed on an automated basis. It is anticipated that this revised methodological protocol will enable a more uniform application of the staging procedure.

/pdf/staging-of-alzheimer-disease-associated-neurofibrillary-1t9afanj75.pdf

Staging of Alzheimer disease-associated neurofibrillary pathology using paraffin sections and immunocytochemistry.

Staging of Alzheimer's disease-related neurofibrillary changes.

The paired helical filament (PHF) is the major component of the neurofibrillary deposits that form a defining neuropathological characteristic of Alzheimer's disease. PHFs are composed of microtubule-associated protein tau, in a hyperphosphorylated state. Hyperphosphorylation of tau results in its inability to bind to microtubules and is believed to precede PHF assembly. However, it is unclear whether hyperphosphorylation of tau is either necessary or sufficient for PHF formation. Here we show that non-phosphorylated recombinant tau isoforms with three microtubule-binding repeats form paired helical-like filaments under physiological conditions in vitro, when incubated with sulphated glycosaminoglycans such as heparin or heparan sulphate. Furthermore, heparin prevents tau from binding to microtubules and promotes microtubule disassembly. Finally, we show that heparan sulphate and hyperphosphorylated tau coexist in nerve cells of the Alzheimer's disease brain at the earliest known stages of neurofibrillary pathology. These findings, with previous studies which show that heparin stimulates tau phosphorylation by a number of protein kinases, indicate that sulphated glycosaminoglycans may be a key factor in the formation of the neurofibrillary lesions of Alzheimer's disease.

Assembly of microtubule-associated protein tau into Alzheimer-like filaments induced by sulphated glycosaminoglycans

Direct Binding of Reelin to VLDL Receptor and ApoE Receptor 2 Induces Tyrosine Phosphorylation of Disabled-1 and Modulates Tau Phosphorylation

The pathway leading from soluble and monomeric to hyperphosphorylated, insoluble and filamentous tau protein is at the centre of many human neurodegenerative diseases, collectively referred to as tauopathies. Dominantly inherited mutations in MAPT, the gene that encodes tau, cause forms of frontotemporal dementia and parkinsonism, proving that dysfunction of tau is sufficient to cause neurodegeneration and dementia. However, most cases of tauopathy are not inherited in a dominant manner. The first tau aggregates form in a few nerve cells in discrete brain areas. These become self propagating and spread to distant brain regions in a prion-like manner. The prevention of tau aggregation and propagation is the focus of attempts to develop mechanism-based treatments for tauopathies.

https://www.thelancet.com/pdfs/journals/laneur/PIIS1474-4422(13)70090-5.pdf

Tau pathology and neurodegeneration

A modified form of the microtubule-associated protein Tau is the major component of the paired helical filaments (PHF) found in Alzheimer's disease. The characterization of these posttranslational Tau modifications is hindered by the lack of sufficient PHF-Tau-specific markers. Here we describe several monoclonal antibodies, prepared by immunization with PHF, two of which showed a selective specificity for PHF-Tau without cross-reactivity with normal Tau. Epitope recognition by these two monoclonals was sensitive to alkaline phosphatase treatment. In Western blotting these monoclonal antibodies reacted specifically with the abnormally phosphorylated epitopes on Alzheimer's disease-associated PHF-Tau. One of the new antibodies can be used for the construction of a sandwich enzyme-linked immunosorbent assay for the specific detection of PHF-Tau without cross-reactivity to normal Tau proteins.

Monoclonal antibodies with selective specificity for Alzheimer Tau are directed against phosphatase-sensitive epitopes.

The phosphatase inhibitor okadaic acid induces a phosphorylated paired helical filament tau epitope in human LA-N-5 neuroblastoma cells.

The invention relates to a monoclonal antibody which forms an immunological complex with an epitope of an antigen belonging to normal human tau protein as well as abnormally phosphorylated human tau protein, with said tau protein being liable to be obtained from a brain homogenate, itself isolated from human cerebral cortex. The monoclonal antibodies of the invention can be used to detect tau and abnormally phosphorylated tau in brain extracts and in unconcentrated cerebrospinal fluid.

Monoclonal antibodies directed against the microtubule-associated protein tau, hybridomas secreting these antibodies, antigen recognition by these monoclonal antibodies and their applications

The invention deals with isolated human tau peptide epitopes of SEQ ID Nos: 1 to 4, 7 and 15 to 20 which have the capability of binding AT120 monoclonal antibody.

Isolated human tau peptide

An isolated human tau peptide epitope which specifically binds monoclonal antibody AT120 consisting of the amino acid sequence selected from the group consisting of SEQ ID Nos. 2, 3, 4, 15, 16, 17, 18, 19 and 20.

Marc Vandermeeren

Papers

Monoclonal antibodies with selective specificity for Alzheimer Tau are directed against phosphatase-sensitive epitopes.

The phosphatase inhibitor okadaic acid induces a phosphorylated paired helical filament tau epitope in human LA-N-5 neuroblastoma cells.

Monoclonal antibodies directed against the microtubule-associated protein tau, hybridomas secreting these antibodies, antigen recognition by these monoclonal antibodies and their applications

Isolated human tau peptide

Isolated human tau peptide epitope which specifically binds monoclonal antibody AT120.