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Thomas, T. L.

Publications and source records attributed to Thomas, T. L..

3 recordsLinked to original sources

Endogenous pathology in tauopathy mice progresses via brain networks

Neurodegenerative tauopathies are hypothesized to propagate via brain networks. This is uncertain because we have lacked precise network resolution of pathology. We therefore developed whole-brain staining methods with anti-p-tau nanobodies and imaged in 3D PS19 tauopathy mice, which have pan-neuronal expression of full-length human tau containing the P301S mutation. We analyzed patterns of p-tau deposition across established brain networks at multiple ages, testing the relationship between structural connectivity and patterns of progressive pathology. We identified core regions with early tau deposition, and used network propagation modeling to determine the link between tau pathology and connectivity strength. We discovered a bias towards retrograde network-based propagation of tau. This novel approach establishes a fundamental role for brain networks in tau propagation, with implications for human disease. One-Sentence SummaryNovel whole brain imaging of p-tau deposition reveals retrograde-dominant network propagation in a tauopathy mouse model.

neuroscience↗

Tau monomer encodes strains

Tauopathies have diverse presentation, progression, and neuropathology. They are linked to tau prion strains, self-replicating assemblies of unique quaternary conformation. Strains can be propagated indefinitely in cultured cells, and induce unique patterns of transmissible neuropathology upon inoculation into mice. Aggregates from a single strain reproduce only that strain upon re-inoculation into cells or mice. DS9 and DS10 cell lines propagate distinct synthetic strains. Surprisingly, DS9 monomer inoculated into naive cells encoded an identical \"sub-strain,\" whereas DS10 monomer encoded multiple sub-strains. Sub-strains produced distinct pathology upon inoculation into a tauopathy mouse model (PS19). Brain-derived tau monomer from an Alzheimers brain encoded a single strain. Monomer from a corticobasal degeneration brain encoded three sub-strains in which monomer from each encoded all three upon re-inoculation into cells. Tau monomer thus adopts multiple, stable seed-competent conformations, each of which encodes a limited number of strains. This provides insights into the origins of distinct tauopathies.

biochemistry↗

Tau seeding activity anticipates phospho-tau pathology in Alzheimer’s disease

Alzheimers disease (AD) is characterized by accumulation of tau neurofibrillary tangles (NFTs) and, according to the prion model, transcellular propagation of pathological \"seeds\" may underlie its progression. Staging of NFT pathology with phospho-tau antibody is useful to classify AD and primary age-related tauopathy (PART) cases. The locus coeruleus (LC) shows the earliest phospho-tau signal, whereas other studies suggest that pathology begins in the transentorhinal/entorhinal cortices (TRE/EC). The relationship of tau seeding activity, phospho-tau pathology, and progression of neurodegeneration remains obscure. Consequently, we employed an established cellular biosensor assay to quantify tau seeding activity in fixed human tissue, in parallel with AT8 phospho-tau staining of immediately adjacent sections. We studied four brain regions from each of n=247 individuals across a range of disease stages. We detected the earliest and most robust seeding activity in the TRE/EC. The LC did not uniformly exhibit seeding activity until later NFT stages. We also detected seeding activity in the first temporal gyrus and visual cortex at stages before NFTs and/or AT8-immunopositivity were detectable. AD and putative PART cases exhibited similar patterns of seeding activity that anticipated histopathology across all NFT stages. Our findings are consistent with the prion model and suggest that pathological seeding activity begins in the TRE/EC rather than in the LC, and may offer an important addition to classical histopathology.

neuroscience↗