Benjamin J. Tuck (United Kingdom)
UK Dementia Research Institute at the University of Cambridge
Department of Clinical Neurosciences
I am a final year PhD student in the McEwan Lab at the University of Cambridge UK Dementia Research Institute. I am investigating the mechanisms which mediate the entry of tau to the cytosol after uptake, a key step in the propagation of tau. However, this process is poorly understood. I have developed a novel assay to directly mechanism underlying the cytosolic entry of tau where we have found distinct differences in entry mechanisms between cell types. Importantly, we find that entry to the cytosol occurs upstream of seeded aggregation in neurons.

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CHOLESTEROL IS A BARRIER TO CYTOSOLIC ENTRY AND THE SEEDED AGGREGATION OF TAU

Session Name
1750 - COINCIDENT NEURODEGENERATIVE DISEASE, AMYLOID, TAU , TDP-43 PATHOLOGY (ID 192)
Session Type
SYMPOSIUM
Date
Sat, 19.03.2022
Session Time
05:15 PM - 07:15 PM
Room
ONSITE: 114
Lecture Time
06:15 PM - 06:30 PM
Presenter

Abstract

Aims

The templated aggregation of tau is considered a major pathological event driving the progression of Alzheimer’s Disease and tauopathy. Whilst uptake of tau is a well-documented process, the mechanistic details governing the access of tau assemblies to the cytosol are unknown. We propose the entry of tau to the cytosol occurs upstream and is required for seeded aggregation. To investigate we have developed novel cell-based assays to quantify the entry of tau to the cytosol with picomolar sensitivity.

Methods

We established a sensitive luciferase-based assay to quantify the cytosolic entry of tau assemblies to various cell types including iPSC-derived cortical neurons. By manipulating the endogenous cellular machinery, we can dissect the underlying mechanisms of entry whilst probing the relationship to seeded aggregation.

Results

Cytosolic entry of tau in HEK293 occurs via a clathrin- and dynamin-dependent route with a role for vesicular sorting machinery in maintaining tau inside compartments. Conversely, entry to both primary and iPSC-derived cortical neurons occurs via an atypical clathrin- and dynamin-independent route with an insensitivity to endosomal disruption. Cholesterol extraction or intracellular accumulation starkly modifies neuronal entry with concomitant changes to seeded aggregation in neurons and slice cultures. Additionally, knockdown of Niemann-Pick type C1 protein significantly modified entry, informing the mechanism of mutation in a human tauopathy.

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Conclusions

Taken together, we have demonstrated that entry to the cytosol is upstream and rate-limiting in seeded aggregation. We have found cell-type dependent entry mechanisms with a distinct role for cholesterol in tau spread and disease, further informing the fundamental biology of neurodegeneration.

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