The dual fates of exogenous tau seeds: Lysosomal clearance versus cytoplasmic amplification

Kolay, Sourav; Vega, Anthony R.; Dodd, Dana A.; Pérez, Valérie; Kashmer, Omar M.; White, Charles L.; Diamond, Marc I.

doi:10.1016/j.jbc.2022.102014

Cited by 23 publications

(51 citation statements)

References 26 publications

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“…These experiments indicated that trapping tau at the plasma membrane, for which HSPG binding was required, actually facilitated seeding. Taken together with our observation of dual fates for tau seeds that enter the cell through endocytosis (Kolay et al, 2022), we have concluded that most tau seeds that enter the cell traffic to a lysosomal degradation pathway, while a small percentage of tau seeds directly access the cytoplasm via translocation across the vesicular or plasma membranes.…”

Section: Discussionsupporting

confidence: 66%

“…Once brought into the cell via endocytosis, exogenous tau must somehow exit the vesicle lumen to serve as a template for conversion of endogenous tau monomer in the cytoplasm. The mechanisms by which this occurs are unknown, and could include vesicle rupture (Falcon et al, 2018; Soares et al, 2021; Ugbode et al, 2019), although our recent work suggests this is not required (Kolay et al, 2022). We have developed methods to quantify tau uptake using flow cytometry (Holmes et al, 2013), and to measure induction of intracellular aggregation based on fluorescence resonance energy transfer (FRET) in engineered “biosensor” cell lines (Holmes et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…FRET flow cytometry measures induction of aggregation in thousands of cells. We have observed that while ~100% of cells take up tau fibrils, in <10% will tau initiate intracellular aggregation (Kolay et al, 2022). Our recent work suggests that tau seeds have two fates after uptake: trafficking to the lysosome for immediate degradation, or entry into the cytosol, where clearance occurs via the proteasome (Kolay et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…We have observed that while ~100% of cells take up tau fibrils, in <10% will tau initiate intracellular aggregation (Kolay et al, 2022). Our recent work suggests that tau seeds have two fates after uptake: trafficking to the lysosome for immediate degradation, or entry into the cytosol, where clearance occurs via the proteasome (Kolay et al, 2022). In the vast majority of cases seeding is not associated with vesicle rupture (Kolay et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Our recent work suggests that tau seeds have two fates after uptake: trafficking to the lysosome for immediate degradation, or entry into the cytosol, where clearance occurs via the proteasome (Kolay et al, 2022). In the vast majority of cases seeding is not associated with vesicle rupture (Kolay et al, 2022). We have now sought to define mechanisms of tau uptake and seeding beginning with a CRISPR-Cas9 screen in HEK293T cells.…”

Section: Introductionmentioning

confidence: 99%

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Tau seeds translocate across the cell membrane to initiate aggregation

Dodd

LaCroix

Valdez

et al. 2022

Preprint

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Neurodegenerative tauopathies, including Alzheimer’s disease and related disorders, are caused by intracellular aggregation of tau protein in ordered assemblies. Experimental evidence suggests that tau assemblies propagate pathology across brain networks. Tau seeds enter cells through endocytosis but must access the cytoplasm to serve as templates for their own replication. The mechanism by which this occurs is unknown. To study tau uptake, we began with a whole-genome CRISPR knockout screen, which indicated a requirement vacuolar H+ ATPase (v-ATPase) components. Treatment with Bafilomycin A1, an inhibitor of the v-ATPase, also reduced tau entry. We next tested direct modifiers of endolysosomal trafficking. Dominant-negative Rab5a expression uniquely decreased tau uptake, as did temporary cold temperature during tau exposure, consistent with a primary role of endocytosis in tau uptake. However, despite reducing tau uptake, these interventions all paradoxically increased intracellular seeding. Consequently, we generated giant plasma membrane vesicles (GPMVs), which cannot undergo endocytosis, and observed that tau fibrils and monomer translocated into the vesicles, in addition to TAT peptide, whereas transferrin and albumin did not. In every case, tau required binding to heparan sulfate proteoglycans (HSPGs) for cell uptake, seeding, or GPMV entry. These findings are most consistent with direct translocation of tau seeds across the lipid bilayer, a novel mechanism of entry into the cytoplasm.

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Section: Discussionsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tau seeds translocate across the cell membrane to initiate aggregation

Dodd

LaCroix

Valdez

et al. 2022

Preprint

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Travels with tau prions

Diamond

2023

Cytoskeleton

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Tau was originally identified as a microtubule associated protein, and subsequently recognized to constitute the fibrillar assemblies found in Alzheimer disease and related neurodegenerative tauopathies. Point mutations in the microtubule associated protein tau (MAPT) gene cause dominantly inherited tauopathies, and most predispose it to aggregate. This indicates tau aggregation underlies pathogenesis of tauopathies. Our work has suggested that tau functions as a prion, forming unique intracellular pathological assemblies that subsequently move to other cells, inducing further aggregation that underlies disease progression. Remarkably, in simple cells tau forms stably propagating aggregates of distinct conformation, termed strains. Each strain induces a unique and, in some cases, transmissible, neuropathological phenotype upon inoculation into a mouse model. After binding heparan sulfate proteoglycans on the plasma membrane, tau assemblies enter cells via macropinocytosis. From within a vesicle, if not trafficked to the endolysosomal system, tau subsequently enters the cytoplasm, where it becomes a template for its own replication, apparently after processing by valosin containing protein. The smallest seed unit is a stable monomer, which suggests that initial folding events in tau presage subsequent pathological aggregation. The study of tau prions has raised important questions about basic cell biological processes that underlie their replication and propagation, with implications for therapy of tauopathies.

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