Biology subjects

Prusiner, S. B.

Publications and source records attributed to Prusiner, S. B..

6 recordsLinked to original sources

bioRxiv2026

Cryo-EM Structures of Infectious Low-Twist α-Synuclein Filaments in Lewy Bodies

-Synuclein (aSyn) aggregation within Lewy bodies underlies Parkinson's disease and associated dementias. These aggregates are often comprised of amyloid filaments, most of which appear untwisted or have extremely low twist, complicating high-resolution structural determination by cryogenic electron microscopy (cryo-EM). Here, we isolated filaments from the brain tissue of a patient with dementia with Lewy bodies and show infectivity in a cell line system that propagates Lewy aSyn. Then, we determined 2.3-2.9 [A] cryo-EM structures of low-twist aSyn filaments from this tissue and from a publicly available Parkinson's disease dementia dataset. In both structures, the protofilament adopts a fold highly similar to the canonical Lewy fold with conserved cofactor and peptidic densities. Compared to previously resolved high-twist filaments, the low-twist filament is left-handed and flattened along the filament axis, resulting in register shifts of interlayer contacts, while preserving the overall architecture. Our results establish that low-twist filaments, which include over 75% of disease-associated Lewy aSyn amyloids, share a common structural core with high-twist forms and are the predominant aSyn species in samples that engage in templated infection.

biophysics↗

bioRxiv2024

Structure of a novel α-synuclein filament fold from multiple system atrophy

Multiple system atrophy (MSA) is a synucleinopathy, a group of related diseases characterized by the accumulation of -synuclein aggregates in the brain. In MSA, these aggregates form glial cytoplasmic inclusions, which contain abundant cross-{beta} amyloid filaments. Structures of -synuclein filaments isolated from MSA patient tissue were determined by cryo-electron microscopy (cryo-EM), revealing three discrete folds that are distinct from -synuclein filaments associated with other synucleinopathies. Here, we use cryo-EM classification methods to characterize filaments from one individual with MSA and identify a novel, low-populated MSA filament fold (designated Type I2) in addition to a predominant class comprising MSA Type II2. The 3.3-[A] resolution structure of the Type I2 filament reveals a fold consisting of two asymmetric protofilaments. One is identical to a previously solved Type I protofilament, while the second adopts a novel fold that is chimeric between two previously reported Type I and II protofilaments. These results further define disease-specific folds of -synuclein filaments that develop in MSA and have implications for the design of therapeutic and diagnostic molecules that target disease.

biophysics↗

bioRxiv2024

Cryo-EM Structures Reveal Tau Filaments from Down Syndrome Adopt Alzheimer's Disease Fold

Down syndrome (DS) is a common genetic condition caused by trisomy of chromosome 21. Among their complex clinical features, including musculoskeletal, neurological, and cardiovascular disabilities, individuals with DS have an increased risk of developing progressive dementia and early-onset Alzheimers disease (AD). This dementia is attributed to the increased gene dosage of the amyloid-{beta} (A{beta}) precursor protein gene, the formation of self-propagating A{beta} and tau prion conformers, and the deposition of neurotoxic A{beta} plaques and tau neurofibrillary tangles. Tau amyloid fibrils have previously been established to adopt many distinct conformations across different neurodegenerative conditions. Here, we report the characterization of brain samples from four DS cases spanning 36 to 63 years of age by spectral confocal imaging with conformation-specific dyes and cryo-electron microscopy (cryo-EM) to determine structures of isolated tau fibrils. High-resolution structures revealed paired helical filament (PHF) and straight filament (SF) conformations of tau that were identical to those determined from AD cases. The PHFs and SFs are made of two C-shaped protofilaments, each containing a cross-{beta}/{beta}-helix motif. Similar to filaments from AD cases, most filaments from the DS cases adopted the PHF form, while a minority (approximately 20%) formed SFs. Samples from the youngest individual with no documented dementia had sparse tau deposits. To isolate tau for cryo-EM from this challenging sample we used a novel affinity-grid method involving a graphene oxide surface derivatized with anti-tau antibodies. This method improved isolation and revealed that primarily tau PHFs and a minor population of chronic traumatic encephalopathy type II-like filaments were present in this youngest case. These findings expand the similarities between AD and DS to the molecular level, providing insight into their related pathologies and the potential for targeting common tau filament folds by small-molecule therapeutics and diagnostics.

neuroscience↗

bioRxiv2022

Stacked binding of a small molecule PET tracer to Alzheimer's tau paired helical filaments

Neurodegenerative diseases (NDs) are characterized by the formation of amyloid filaments that adopt disease-specific conformations in the brain. Recently developed small molecules hold promise as diagnostics and possible therapeutics for NDs, but their binding mechanisms to amyloid filaments remain unknown. Here, we used cryo-electron microscopy (cryo-EM) to determine a 2.7 [A] structure of Alzheimers disease patient-derived tau paired-helical filaments incubated with the GTP-1 PET probe. GTP-1 is bound stoichiometrically along an exposed cleft of each protofilament in a stacked arrangement that matches the fibrils symmetry. Multiscale modeling revealed favorable pi-pi aromatic stacking interactions between GTP-1 molecules that, together with small molecule-protein contacts, result in high affinity binding. This binding mode offers new insight into designing compounds for diagnosis and treatment of specific NDs. One Sentence SummaryCryo-EM structure reveals a novel stacked arrangement of the GTP-1 PET ligand bound to Alzheimers disease tau filaments.

biophysics↗

bioRxiv2021

Tau aggregates are RNA-protein assemblies that mis-localize multiple nuclear speckle components

Tau aggregates contribute to neurodegenerative diseases including frontotemporal dementia and Alzheimers disease (AD). Although RNA promotes tau aggregation in vitro, whether tau aggregates in cells contain RNA is unknown. We demonstrate in cell culture and mouse brains that both cytosolic and nuclear tau aggregates contain RNA, with enrichment for snRNAs and snoRNAs. Nuclear tau aggregates colocalize with and alter the composition, dynamics, and organization of nuclear speckles, which are membraneless organelles involved in pre-mRNA splicing. Moreover, several nuclear speckle components, including SRRM2, mislocalize to cytosolic tau aggregates in cells, mouse brains, and patient brains with AD, frontotemporal dementia (FTD), and corticobasal degeneration (CBD). Consistent with these alterations we observe the presence of tau aggregates is sufficient to alter pre-mRNA splicing. This work identifies tau alteration of nuclear speckles as a feature of tau aggregation that may contribute to the pathology of tau aggregates.

molecular biology↗

bioRxiv2021

Trans-channel fluorescence learning improves high-content screening for Alzheimer's disease therapeutics

In microscopy-based drug screens, fluorescent markers carry critical information on how compounds affect different biological processes. However, practical considerations may hinder the use of certain fluorescent markers. Here, we present a deep learning method for overcoming this limitation. We accurately generated predicted fluorescent signals from other related markers and validated this new machine learning (ML) method on two biologically distinct datasets. We used the ML method to improve the selection of biologically active compounds for Alzheimers disease (AD) from high-content high-throughput screening (HCS). The ML method identified novel compounds that effectively blocked tau aggregation, which would have been missed by traditional screening approaches unguided by ML. The method improved triaging efficiency of compound rankings over conventional rankings by raw image channels. We reproduced this ML pipeline on a biologically independent cancer-based dataset, demonstrating its generalizability. The approach is disease-agnostic and applicable across diverse fluorescence microscopy datasets.

pharmacology and toxicology↗