Biology subjects

Murayama, S.

Publications and source records attributed to Murayama, S..

12 recordsLinked to original sources

bioRxiv2026

Prion-like transmission of human tau strains in the mouse brain

Most neurodegenerative diseases are believed to spread through the brain by prion-like mechanisms, where filamentous protein assemblies self-propagate by templated seeding 1. Distinct conformations of amyloid filaments are thought to provide the physical basis for the strains that lead to different diseases 2. However, a central pillar of the prion hypothesis, that strains retain their structural identity upon transmission, has not been demonstrated. Here we show that the injection of tau filaments from the brains of individuals with Alzheimers disease or corticobasal degeneration into the brains of wildtype mice leads to the seeded assembly of amyloid filaments made of mouse tau with the same structures as those of the seeds. Thereby, we establish that, like prion strains, tau filaments propagate through templated seeding, and that the mouse is a suitable model to study the molecular mechanisms by which distinct tau folds drive disease-specific pathology in the brain.

neuroscience↗

bioRxiv2024

Selective agonism of GPR34 stimulates microglial uptake and clearance of amyloid β fibrils

Microglia, the primary immune cells of the central nervous system, play a crucial role in maintaining brain homeostasis through phagocytosis of various substrates, including amyloid-{beta} (A{beta}) fibrils, a hallmark of Alzheimer disease (AD) pathology. However, the molecular mechanisms regulating microglial A{beta} uptake remain poorly understood. Here, we identified GPR34, a Gi/o-coupled receptor highly expressed in microglia, as a novel regulator of fibrillar A{beta} phagocytosis. Treatment with a selective GPR34 agonist, M1, specifically enhanced uptake of A{beta} fibrils, but not its monomer or oligomer, in both mouse and human microglia. Mechanistically, M1 reduced intracellular cAMP levels, which inversely correlated with A{beta} uptake activity. Importantly, a single intrahippocampal injection of M1 in an AD mouse model significantly increased microglial A{beta} uptake in vivo. Furthermore, single-nucleus RNA-sequencing analysis of Japanese AD patient samples revealed a significant reduction of GPR34 expression in microglia from AD patients compared to controls. We also observed an age-dependent decline in microglial GPR34 expression in both human and mouse datasets, suggesting a potential contribution of GPR34 downregulation to age-related A{beta} accumulation and AD risk. Collectively, our findings identify GPR34 as a promising target for modulating microglial A{beta} clearance and highlight the therapeutic potential of GPR34 agonists in AD. Significance statementAlzheimer disease (AD) is characterized by amyloid-{beta} (A{beta}) accumulation in the brain. Microglia, the brains immune cells, play a crucial role in the metabolism of A{beta}. We discovered that activating the microglial receptor GPR34 with a selective agonist enhances the phagocytosis of A{beta} fibrils, a key pathogenic form of A{beta}. Importantly, GPR34 expression decreases with aging and AD progression, potentially contributing to impaired A{beta} clearance. Our findings highlight GPR34 as a promising therapeutic target for AD, as boosting its activity could promote A{beta} clearance and slow disease progression. This study provides valuable insights into microglial function in AD and offers a novel strategy for developing disease-modifying therapies.

neuroscience↗

bioRxiv2023

Cryo-EM structures of tau filaments from SH-SY5Y cells seeded with brain extracts from cases of Alzheimer's disease and corticobasal degeneration

The formation of amyloid filaments through templated seeding is believed to underlie the propagation of pathology in most human neurodegenerative diseases. A widely used model system to study this process is to seed amyloid filament formation in cultured cells using human brain extracts. Here, we report the electron cryo-microscopy (cryo-EM) structures of tau filaments from undifferentiated seeded SH-SY5Y cells, that transiently expressed N-terminally HA-tagged 1N3R or 1N4R human tau, using brain extracts from individuals with AD or CBD. Although the resulting filament structures differed from those of the brain seeds, some degree of structural templating was observed. Studying templated seeding in cultured cells, and determining the structures of the resulting filaments, can thus provide insights into the cellular aspects underlying neurodegenerative diseases.

neuroscience↗

bioRxiv2022

Cryo-EM structures of α-synuclein filaments from Parkinson's disease and dementia with Lewy bodies

Parkinsons disease (PD) is the most common movement disorder, with resting tremor, rigidity, bradykinesia and postural instability being major symptoms (1). Neuropathologically, it is characterised by the presence of abundant filamentous inclusions of -synuclein in the form of Lewy bodies and Lewy neurites in some brain cells, including dopaminergic nerve cells of the substantia nigra (2). PD is increasingly recognised as a multisystem disorder, with cognitive decline being one of its most common non-motor symptoms. Many patients with PD develop dementia more than 10 years after diagnosis (3). PD dementia (PDD) is clinically and neuropathologically similar to dementia with Lewy bodies (DLB), which is diagnosed when cognitive impairment precedes parkinsonian motor signs or begins within one year from their onset (4). In PDD, cognitive impairment develops in the setting of well-established PD. Besides PD and DLB, multiple system atrophy (MSA) is the third major synucleinopathy (5). It is characterised by the presence of abundant filamentous -synuclein inclusions in brain cells, especially oligodendrocytes (Papp-Lantos bodies). We previously reported the electron cryo-microscopy (cryo-EM) structures of two types of -synuclein filaments extracted from the brains of individuals with MSA (6). Each filament type is made of two different protofilaments. Here we report that the cryo-EM structures of -synuclein filaments from the brains of individuals with PD, PDD and DLB are made of a single protofilament (Lewy fold) that is markedly different from the protofilaments of MSA. These findings establish the existence of distinct molecular conformers of assembled -synuclein in neurodegenerative disease.

neuroscience↗

bioRxiv2022

Proteomic profile of nuclei containing p62-positive inclusions in neuronal intranuclear inclusion disease

Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disease characterized by eosinophilic hyaline intranuclear inclusions in the neurons, glial cells, and other somatic cells. Although CGG repeat expansions in NOTCH2NLC have been identified in most East Asian patients with NIID, the pathophysiology of NIID remains unclear. Intranuclear inclusions are the pathological hallmark of NIID. Previously, immunohistochemistry has revealed that intranuclear inclusions are ubiquitin-, p62-, and SUMO-1-positive, suggesting the possible alteration of the ubiquitin-proteasomal protein degradation system in the nuclei with inclusions. However, the molecular mechanisms within these nuclei remain unclear. Herein, we analyzed the proteomic profile of nuclei with p62-positive inclusions in NIID with CGG repeat expansion in NOTCH2NLC to discover the proteins involved in the NIID pathophysiology. We used fluorescence-activated cell sorting and liquid chromatography-tandem mass spectrometry (LC-MS/MS) to quantify each protein identified in the nuclei with p62-positive inclusions. The distribution of increased proteins in the autopsy brain samples from three NIID patients was confirmed via immunofluorescence. Overall, 526 proteins were identified, of which 243 were consistently quantified using MS. A 1.4-fold increase was consistently observed for 20 proteins in nuclei with p62-positive inclusions compared to those without. Fifteen proteins identified with medium or high confidence in the LC-MS/MS analysis were further evaluated. Gene ontology enrichment analysis showed enrichment of several terms, including poly(A) RNA binding, nucleosomal DNA binding, and protein binding. Immunofluorescence studies confirmed that the fluorescent intensities of increased RNA-binding proteins identified by proteomic analysis, namely hnRNP A3, hnRNP A2/B1, and hnRNP C1/C2, were higher in the nuclei with p62-positive inclusions than those without; however, they were not confined to the intranuclear inclusions. We identified several increased proteins in nuclei with p62-positive inclusions. These data can form the basis for understanding the pathophysiology of NIID.

biochemistry↗

bioRxiv2022

Conformational change in the monomeric alpha-synuclein imparts fibril polymorphs

-Synuclein (Syn) inclusions are a pathological hallmark of several neurodegenerative disorders. While cryo-electron microscopy studies have revealed distinct fibril polymorphs across different synucleinopathies, the molecular switches controlling polymorphism remained unveiled. In this study, we found that fibril morphology is associated with the conformational state of monomeric Syn. Through systematic manipulation of the ionic strength and temperature, we pinpoint two distinct polymorphs: a twisted morphology at low ionic strength and temperature, and a rod-like morphology at higher ionic strength and temperature. Most strikingly, we found that a specific conformational change in the C-terminal domain of the monomeric Syn serves as the master switch for the formation of polymorphs. Interestingly, this conformational change can be triggered by calcium binding to the C-terminus, connecting environmental factors to specific fibril architectures. Our results unmask the C-terminal domain as a key player for orchestrating Syn fibril morphology, providing significant insights into the fibrogenesis of Syn. Significance StatementThe Syn C-terminus domain acts as the master switch programming its fibril polymorphism.

biophysics↗

bioRxiv2021

Age-dependent formation of TMEM106B amyloid filaments in human brain

Many age-dependent neurodegenerative diseases, like Alzheimers and Parkinsons, are characterised by abundant inclusions of amyloid filaments. Filamentous inclusions of the proteins tau, amyloid-{beta} (A{beta}), -synuclein and TDP-43 are the most common. Here, we used electron cryo-microscopy (cryo-EM) structure determination to show that residues 120-254 of the lysosomal type II transmembrane protein 106B (TMEM106B) also form amyloid filaments in the human brain. We solved cryo-EM structures of TMEM106B filaments from the brains of 22 individuals with neurodegenerative conditions, including sporadic and inherited tauopathies, A{beta}-amyloidoses, synucleinopathies and TDP-43opathies, as well as from the brains of two neurologically normal individuals. We observed three different TMEM106B folds, with no clear relationship between folds and diseases. The presence of TMEM106B filaments correlated with that of a 29 kDa sarkosyl-insoluble fragment of the protein on Western blots. The presence of TMEM106B filaments in the brains of older, but not younger, neurologically normal individuals indicates that they form in an age-dependent manner.

neuroscience↗

bioRxiv2021

Structure-based Classification of Tauopathies

Ordered assembly of the tau protein into filaments characterizes multiple neurodegenerative diseases, which are called tauopathies. We previously reported that by electron cryo-microscopy (cryo-EM), tau filament structures from Alzheimers disease (1,2), chronic traumatic encephalopathy (CTE) (3), Picks disease (4) and corticobasal degeneration (CBD) (5) are distinct. Here we show that the structures of tau filaments from typical and atypical progressive supranuclear palsy (PSP), the most common tauopathy after Alzheimers disease, define a previously unknown, three-layered fold. Moreover, the tau filament structures from globular glial tauopathy (GGT, Types I and II) are similar to those from PSP. The tau filament fold of argyrophilic grain disease (AGD) differs from the above and resembles the four-layered CBD fold. The majority of tau filaments from aging-related tau astrogliopathy (ARTAG) also have the AGD fold. Surprisingly, tau protofilament structures from inherited cases with mutations +3/+16 in intron 10 of MAPT, the microtubule-associated protein tau gene, are identical to those from AGD, suggesting that a relative overproduction of four-repeat tau can give rise to the AGD fold. Finally, tau filament structures from cases of familial British dementia (FBD) and familial Danish dementia (FDD) are the same as those from Alzheimers disease and primary age-related tauopathy (PART). These structures provide the basis for a classification of tauopathies that also allows identification of new entities, as we show here for a case diagnosed as PSP, but with abundant spherical 4R tau inclusions in limbic and other brain areas. The structures of the tau fold of this new disease (Limbic-predominant Neuronal inclusion body 4R Tauopathy, LNT) were intermediate between those of GGT and PSP.

neuroscience↗

bioRxiv2020

Seeded assembly in vitro does not replicate the structures of α-synuclein filaments from multiple system atrophy

The propagation of conformational strains by templated seeding is central to the prion concept. Seeded assembly of -synuclein into filaments is believed to underlie the prion-like spreading of protein inclusions in a number of human neurodegenerative diseases, including Parkinson's disease, dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). We previously determined the atomic structures of -synuclein filaments from the putamen of five individuals with MSA. Here, we used filament preparations from three of these brains for the in vitro seeded assembly of recombinant human -synuclein. We find that the structures of the seeded assemblies differ from those of the seeds, suggesting that additional, as yet unknown, factors play a role in the propagation of pathology. Identification of these factors will be essential for understanding the prion-like spreading of -synuclein proteinopathies.

molecular biology↗

bioRxiv2020

Non-allelic homologous recombination of Alu and LINE-1 elements generates somatic complexity in human genomes.

Millions of Alu and L1 copies in our genomes contribute to evolution and genetic disorders via non-allelic homologous recombination, but the somatic extent of these rearrangements has not been systematically investigated. Here we combine short and long DNA reads sequencing of repeat elements with a new bioinformatic pipeline to show that somatic recombination of Alu and L1 elements is common in human genomes. We report new tissue-specific recombination hallmarks, and show that retroelements acting as recombination hotspots are enriched in centromeres and cancer genes. We compare recombination profiles in human induced pluripotent stem cells and differentiated neurons and show that neuron-specific recombination of repeat elements accompanies chromatin changes during cell-fate determination. Finally, we find that somatic recombination profiles are altered in Parkinsons and Alzheimers disease, indicating a link between retroelements recombination and genomic instability in neurodegeneration. This work shows that somatic recombination of repeat elements contributes massively to genomic diversity in health and disease.

genomics↗

bioRxiv2020

Structures of α-synuclein filaments from multiple system atrophy

Synucleinopathies are human neurodegenerative diseases that include multiple system atrophy (MSA), Parkinsons disease, Parkinsons disease dementia (PDD) and dementia with Lewy bodies (DLB) (1). Existing treatments are at best symptomatic. These diseases are characterised by the presence in brain cells of filamentous inclusions of -synuclein, the formation of which is believed to cause disease (2, 3). However, the structures of -synuclein filaments from human brain are not known. Here we show, using electron cryo-microscopy, that -synuclein inclusions from MSA are made of two types of filaments, each of which consists of two different protofilaments. Non-proteinaceous molecules are present at the protofilament interfaces. By two-dimensional class averaging, we show that -synuclein filaments from the brains of patients with MSA and DLB are different, suggesting that distinct conformers (or strains) characterise synucleinopathies. As was the case of tau assemblies (4-9), the structures of -synuclein filaments extracted from the brains of individuals with MSA differ from those formed in vitro using recombinant proteins, with implications for understanding the mechanisms of aggregate propagation and neurodegeneration in human brain. These findings have diagnostic and potential therapeutic relevance, especially in view of the unmet clinical need to be able to image filamentous -synuclein inclusions in human brain.

neuroscience↗

bioRxiv2019

Novel tau filament fold in corticobasal degeneration, a four-repeat tauopathy

Corticobasal degeneration (CBD) is a neurodegenerative tauopathy that is characterised by motor and cognitive disturbances (1-3). A higher frequency of the H1 haplotype of MAPT, the tau gene, is present in cases of CBD than in controls (4, 5) and genome-wide association studies have identified additional risk factors (6). By histology, astrocytic plaques are diagnostic of CBD (7, 8), as are detergent-insoluble tau fragments of 37 kDa by SDS-PAGE (9). Like progressive supranuclear palsy (PSP), globular glial tauopathy (GGT) and argyrophilic grain disease (AGD) (10), CBD is characterised by abundant filamentous tau inclusions that are made of isoforms with four microtubule-binding repeats (4R) (11-15). This distinguishes 4R tauopathies from Picks disease, filaments of which are made of three-repeat (3R) tau isoforms, and from Alzheimers disease and chronic traumatic encephalopathy (CTE), where both 3R and 4R tau isoforms are found in the filaments (16). Here we report the structures of tau filaments extracted from the brains of three individuals with CBD using electron cryo-microscopy (cryo-EM). They were identical between cases, but distinct from those of Alzheimers disease, Picks disease and CTE (17-19). The core of CBD filaments comprises residues K274-E380 of tau, spanning the last residue of R1, the whole of R2, R3 and R4, as well as 12 amino acids after R4. It adopts a novel four-layered fold, which encloses a large non-proteinaceous density. The latter is surrounded by the side chains of lysine residues 290 and 294 from R2 and 370 from the sequence after R4. CBD is the first 4R tauopathy with filaments of known structure.

neuroscience↗