Showing papers by "Michel Goedert published in 2022"

Cryo-EM structures of amyloid-β 42 filaments from human brains

Abstract: Description Hi-res view of human Aβ42 filaments Alzheimer’s disease is characterized by a loss of memory and other cognitive functions and the filamentous assembly of Aβ and tau in the brain. The assembly of Aβ peptides into filaments that end at residue 42 is a central event. Yang et al. used electron cryo–electron microscopy to determine the structures of Aβ42 filaments from human brain (see the Perspective by Willem and Fändrich). They identified two types of related S-shaped filaments, each consisting of two identical protofilaments. These structures will inform the development of better in vitro and animal models, inhibitors of Aβ42 assembly, and imaging agents with increased specificity and sensitivity. —SMH In Alzheimer’s disease and other conditions, two structurally related protofilaments form type I and type II Aβ42 filaments. Filament assembly of amyloid-β peptides ending at residue 42 (Aβ42) is a central event in Alzheimer’s disease. Here, we report the cryo–electron microscopy (cryo-EM) structures of Aβ42 filaments from human brains. Two structurally related S-shaped protofilament folds give rise to two types of filaments. Type I filaments were found mostly in the brains of individuals with sporadic Alzheimer’s disease, and type II filaments were found in individuals with familial Alzheimer’s disease and other conditions. The structures of Aβ42 filaments from the brain differ from those of filaments assembled in vitro. By contrast, in AppNL-F knock-in mice, Aβ42 deposits were made of type II filaments. Knowledge of Aβ42 filament structures from human brains may lead to the development of inhibitors of assembly and improved imaging agents.

Structures of α-synuclein filaments from human brains with Lewy pathology

Abstract: Parkinson’s disease (PD) is the most common movement disorder, with resting tremor, rigidity, bradykinesia and postural instability being major symptoms1. Neuropathologically, it is characterized by the presence of abundant filamentous inclusions of α-synuclein in the form of Lewy bodies and Lewy neurites in some brain cells, including dopaminergic nerve cells of the substantia nigra2. 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 diagnosis3. 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 onset4. In PDD, cognitive impairment develops in the setting of well-established PD. Besides PD and DLB, multiple system atrophy (MSA) is the third major synucleinopathy5. It is characterized by the presence of abundant filamentous α-synuclein inclusions in brain cells, especially oligodendrocytes (Papp-Lantos bodies). We previously reported the electron cryo-microscopy structures of two types of α-synuclein filament extracted from the brains of individuals with MSA6. Each filament type is made of two different protofilaments. Here we report that the cryo-electron microscopy structures of α-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 α-synuclein in neurodegenerative disease. The authors report on the structures of α-synuclein filaments from the brains of individuals with Parkinson's disease, Parkinson's disease dementia and dementia with Lewy bodies and how they differ from those seen in multiple system atrophy.

Classification of diseases with accumulation of Tau protein

Abstract: Abnormal filaments of known composition in neurons and glia define many sporadic and hereditary human neurodegenerative diseases. The pathogenic significance of filamentous inclusions became evident when cases of dominantly inherited disease were shown to be associated with mutations in the genes encoding the proteins that make up filaments, be they Tau [1–3], Aβ [4, 5], α-synuclein [6], prion protein [7], TDP-43 [8–10] or FUS [11, 12]. By extrapolation, it follows that a gain-of-toxic function resulting from the ordered assembly into filaments may also underlie sporadic forms of disease. Assemblies of the microtubule-associated protein Tau into filaments characterise many neurodegenerative diseases. In humans, MAPT, the gene encoding Tau protein, generates six isoforms (352– 441 amino acids) by alternative mRNA splicing [13]. They differ by the presence or absence of three inserts encoded by exons 2, 3 and 10. Inclusion of exon 10 results in the production of three isoforms with four C-terminal repeats (each repeat is 31 or 32 amino acids long) (4R) and its exclusion in another three isoforms with three repeats (3R). Diseases characterised by the intracellular accumulation of Tau filaments can be divided into three groups, based on the isoform composition of filaments (3R, 4R, 3R + 4R) [14]. In these diseases, be they sporadic or inherited, Tau is extensively modified post-translationally [15–17]. Tauopathy was coined to describe a dominantly inherited neurodegenerative disease with a +3 mutation in intron 10 of MAPT and abundant filamentous inclusions made of 4R Tau [3, 18]. However, this term is also used in neuropathology and neuroscience to refer to the mere presence of Tau in tissues. The terms primary and secondary tauopathies are also being used [19–25], even though mutations in MAPT are the only known aetiology for Tauopathies. Primary tauopathy refers to conditions where the presence of Tau filaments is the main or sole known abnormality or where tau pathology is considered the major contributing factor to neurodegeneration interpreted as main ‘driving force of pathogenesis’, as opposed to other proteins such as Aβ [23, 25– 28]. Primary tauopathies are also included in the group of frontotemporal lobar degeneration (FTLD). The latter is characterised by the predominant atrophy of frontal and temporal lobes of the cerebral cortex and occurs in association with several different proteinopathies [29]. Secondary tauopathy is used when additional ‘driving pathogenic forces’ are believed to be involved [19]. In our view, cases with mutations in MAPT are the only known example of a primary tauopathy, whereas familial Alzheimer’s disease may be secondary tauopathy. These terms should not be used when referring to diseases of unknown aetiology. Diseases with pathologic Tau can be classified on the basis Tau isoforms, 3R, 4R or both 3R and 4R being demonstrable with isoform-specific antibodies or Western blot patterns of sarkosyl-insoluble Tau. The anatomical distribution, along with the histological and cytological characterisation of neuronal and glial tau immunoreactivities, is also needed for clinicopathological classification [19, 20, 30]. Formation of abnormal Tau filaments is a central event in several neurodegenerative diseases. Like the filaments of other pathologic amyloids, Tau filaments have a cross-β conformation [31]. Recently, the Tau folds of Alzheimer’s disease [32, 33], Pick’s disease [34], chronic traumatic encephalopathy (CTE) [35], corticobasal degeneration (CBD) [36, 37], argyrophilic grain disease (AGD), progressive supranuclear palsy (PSP) and globular glial tauopathy (GGT) [38] were shown to be different. The Tau filament fold of primary age-related tauopathy (PART) was identical to the Alzheimer fold, indicating that it can form in the absence of Aβ deposits [39]. The same filament structures have been found for different individuals with a given disease. It is also noteworthy that Tau folds identical to those of Alzheimer’s disease coexisted with cerebral parenchymal Aβ amyloid, PrP amyloid, Abri and ADan amyloid [38, 40]. Tau filament structures from the brains of intron 10 MAPT mutation carriers were identical to those of AGD. Structural analysis of tau filament folds has also led to the discovery of potentially new disease entities [38]. It is now timely to update the existing terminology and reexamine the grouping of disorders associated with intracellular tau accumulation, because (1) there is an increased interest in the role of Tau assembly in neurodegeneration, (2) inconsistent terminology has been used and (3) high-resolution tau filament structures have been determined. Here, we put forward definitions of terms to describe Tau in various conditions, as well as a simple and flexible stratification system that will also allow inclusion of novel pathological entities.

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

Abstract: Parkinson’s 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 α-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 α-synuclein inclusions in brain cells, especially oligodendrocytes (Papp-Lantos bodies). We previously reported the electron cryo-microscopy (cryo-EM) structures of two types of α-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 α-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 α-synuclein in neurodegenerative disease.

Cryo-EM structures of amyloid-β filaments with the Arctic mutation (E22G) from human and mouse brains

Abstract: The Arctic mutation, encoding E693G in the amyloid precursor protein (APP) gene [E22G in amyloid-β (Aβ)], causes dominantly inherited Alzheimer's disease. Here, we report the high-resolution cryo-EM structures of Aβ filaments from the frontal cortex of a previously described case (AβPParc1) with the Arctic mutation. Most filaments consist of two pairs of non-identical protofilaments that comprise residues V12-V40 (human Arctic fold A) and E11-G37 (human Arctic fold B). They have a substructure (residues F20-G37) in common with the folds of type I and type II Aβ42. When compared to the structures of wild-type Aβ42 filaments, there are subtle conformational changes in the human Arctic folds, because of the lack of a side chain at G22, which may strengthen hydrogen bonding between mutant Aβ molecules and promote filament formation. A minority of Aβ42 filaments of type II was also present, as were tau paired helical filaments. In addition, we report the cryo-EM structures of Aβ filaments with the Arctic mutation from mouse knock-in line AppNL-G-F. Most filaments are made of two identical mutant protofilaments that extend from D1 to G37 (AppNL-G-F murine Arctic fold). In a minority of filaments, two dimeric folds pack against each other in an anti-parallel fashion. The AppNL-G-F murine Arctic fold differs from the human Arctic folds, but shares some substructure.

Increase in Tau Pathology in P290S Mapt Knock-In Mice Crossed with AppNL-G-F Mice

Abstract: Abstract Alzheimer’s Disease (AD) is characterized by the pathologic assembly of amyloid β (Aβ) peptide, which deposits into extracellular plaques, and tau, which accumulates in intraneuronal inclusions. To investigate the link between Aβ and tau pathologies, experimental models featuring both pathologies are needed. We developed a mouse model featuring both tau and Aβ pathologies by knocking the P290S mutation into murine Mapt and crossing these MaptP290S knock-in (KI) mice with the AppNL-G-F KI line. MaptP290S KI mice developed a small number of tau inclusions, which increased with age. The amount of tau pathology was significantly larger in AppNL-G-FxMaptP290S KI mice from 18 months of age onward. Tau pathology was higher in limbic areas, including hippocampus, amygdala, and piriform/entorhinal cortex. We also observed AT100-positive and Gallyas-Braak-silver-positive dystrophic neurites containing assembled filamentous tau, as visualized by in situ electron microscopy. Using a cell-based tau seeding assay, we showed that Sarkosyl-insoluble brain extracts from both 18-month-old MaptP290S KI and AppNL-G-FxMaptP290S KI mice were seed competent, with brain extracts from double-KI mice seeding significantly more than those from the MaptP290S KI mice. Finally, we showed that AppNL-G-FxMaptP290S KI mice had neurodegeneration in the piriform cortex from 18 months of age. We suggest that AppNL-G-FxMaptP290S KI mice provide a good model for studying the interactions of aggregation-prone tau, Aβ, neuritic plaques, neurodegeneration, and aging.

New SNCA mutation and structures of α-synuclein filaments from juvenile-onset synucleinopathy

Abstract: A 21-nucleotide duplication in one allele of SNCA was identified in a previously described disease with abundant α-synuclein inclusions that we now call juvenile-onset synucleinopathy (JOS). This mutation translates into the insertion of MAAAEKT after residue 22 of α-synuclein, resulting in a protein of 147 amino acids. Both wild-type and mutant proteins were present in sarkosyl-insoluble material that was extracted from frontal cortex of the individual with JOS and examined by electron cryo-microscopy. The structures of JOS filaments, comprising either a single protofilament, or a pair of protofilaments, revealed a new α-synuclein fold that differs from the folds of Lewy body diseases and multiple system atrophy (MSA). The JOS fold consists of a compact core, the sequence of which (residues 36-100 of wild-type α-synuclein) is unaffected by the mutation, and two disconnected density islands (A and B) of mixed sequences. There is a non-proteinaceous cofactor bound between the core and island A. The JOS fold resembles the common substructure of MSA Type I and Type II dimeric filaments, with its core segment approximating the C-terminal body of MSA protofilaments B and its islands mimicking the N-terminal arm of MSA protofilaments A. The partial similarity of JOS and MSA folds extends to the locations of their cofactor-binding sites. In vitro assembly of recombinant wild-type α-synuclein, its insertion mutant and their mixture yielded structures that were distinct from those of JOS filaments. Our findings provide insight into a possible mechanism of JOS fibrillation in which mutant α-synuclein of 147 amino acids forms a nucleus with the JOS fold, around which wild-type and mutant proteins assemble during elongation.

Cryo-EM structures of chronic traumatic encephalopathy tau filaments with PET ligand flortaucipir

Abstract: Positron emission tomography (PET) imaging allows monitoring the progression of amyloid aggregation in the living brain. [18F]-Flortaucipir is the only approved PET tracer compound for the visualisation of tau aggregation. Here, we describe cryo-EM experiments on tau filaments in the presence and absence of flortaucipir. We used tau filaments isolated from the brain of an individual with Alzheimer’s disease (AD), and from the brain of an individual with primary age-related tauopathy (PART) with a co-pathology of chronic traumatic encephalopathy (CTE). Unexpectedly, we were unable to visualise additional cryo-EM density for flortaucipir for AD paired helical or straight filaments (PHFs or SFs), but we did observe density for flortaucipir binding to CTE Type I filaments from the case with PART. In the latter, flortaucipir binds in a 1:1 molecular stoichiometry with tau, adjacent to lysine 353 and aspartate 358. By adopting a tilted geometry with respect to the helical axis, the 4.7 Å distance between neighbouring tau monomers is reconciled with the 3.5 Å distance consistent with π-π-stacking between neighbouring molecules of flortaucipir.

A tribute to John Q. Trojanowski (1946–2022), neuropathologist extraordinaire

Abstract: John Trojanowski, who died on February 8, was a giant in the field of neuropathology, at the forefront of research on tauopathies, synucleinopathies and TDP43 proteinopathies. It is less well known that he also made substantial contributions to the study of tumours of the nervous system. However, largely because of our own limitations, this article mentions only John's work on neurodegenerative diseases. Abundant brain cell inclusions characterise most agerelated human neurodegenerative diseases. They were first identified by light microscopy following the use of newly developed silver staining techniques at the turn of the 20th century. From the 1960s onwards, electron microscopic examination showed that inclusions contain abnormal amyloid filaments. Over the past 40 years, the major components of these filaments have been identified, and their formation has been shown to be linked to the aetiology and pathogenesis of neurodegenerative diseases. This work, to which John was a major contributor, took the study of these diseases from a descriptive to a more mechanistic level. As a result, we now speak of tauopathies, synucleinopathies, TDP43 proteinopathies and others. Copathologies have also come to the fore. Thus, inclusions of αsynuclein and TDP43 are commonly found in Alzheimer's disease (AD), together with abundant tau and Aβ inclusions. The scientific contributions of John Trojanowski are inextricably linked with those of his partner in life, Virginia Lee. John's clinical and neuropathological expertise, together with Virginia's immunological, as well as cell and molecular biological acumen, were an ideal package. AD, the most common neurodegenerative disease, is defined by the presence of abundant extracellular deposits and intraneuronal inclusions (plaques and tangles). In the mid1980s, Aβ was identified as the major plaque component. Tangles are made of paired helical and some straight filaments. Tau protein was identified as an integral component of these filaments in the midlate 1980s [1]. However, the insolubility of filaments isolated from tangle fragments made it difficult to exclude the presence of proteins other than tau. John and colleagues, who came to tau through work on neurofilaments, used a method for extracting more soluble filaments, to show that they were only made of tau [2]. The latter is now known to be the most commonly misfolded protein in human neurodegenerative diseases. In recent years, John and colleagues have also made important contributions to the expanding field of the prionlike behaviour of assembled tau. Work on the enhancement of seeded tau aggregation by Aβ plaques has suggested a novel way for looking at the important, but unresolved, issue of the connection between Aβ and tau [3]. In the early 1990s, we began to collaborate with John and Virginia and have been friends ever since. John often Received: 21 February 2022 | Accepted: 1 March 2022

A tribute to John Q. Trojanowski (1946-2022), neuropathologist extraordinaire.

Abstract: John Trojanowski, who died on February 8, was a giant in the field of neuropathology, at the forefront of research on tauopathies, synucleinopathies and TDP-43 proteinopathies. It is less well known that he also made substantial contributions to the study of tumours of the nervous system. However, largely because of our own limitations, this article mentions only John's work on neurodegenerative diseases. Abundant brain cell inclusions characterise most age-related human neurodegenerative diseases. They were first identified by light microscopy following the use of newly developed silver staining techniques at the turn of the 20th century. From the 1960s onwards, electron microscopic examination showed that inclusions contain abnormal amyloid filaments. Over the past 40 years, the major components of these filaments have been identified, and their formation has been shown to be linked to the aetiology and pathogenesis of neurodegenerative diseases. This work, to which John was a major contributor, took the study of these diseases from a descriptive to a more mechanistic level. As a result, we now speak of tauopathies, synucleinopathies, TDP-43 proteinopathies and others. Co-pathologies have also come to the fore. Thus, inclusions of α-synuclein and TDP-43 are commonly found in Alzheimer's disease (AD), together with abundant tau and Aβ inclusions. The scientific contributions of John Trojanowski are inextricably linked with those of his partner in life, Virginia Lee. John's clinical and neuropathological expertise, together with Virginia's immunological, as well as cell and molecular biological acumen, were an ideal package. AD, the most common neurodegenerative disease, is defined by the presence of abundant extracellular deposits and intraneuronal inclusions (plaques and tangles). In the mid-1980s, Aβ was identified as the major plaque component. Tangles are made of paired helical and some straight filaments. Tau protein was identified as an integral component of these filaments in the mid-late 1980s [1]. However, the insolubility of filaments isolated from tangle fragments made it difficult to exclude the presence of proteins other than tau. John and colleagues, who came to tau through work on neurofilaments, used a method for extracting more soluble filaments, to show that they were only made of tau [2]. The latter is now known to be the most commonly misfolded protein in human neurodegenerative diseases. In recent years, John and colleagues have also made important contributions to the expanding field of the prion-like behaviour of assembled tau. Work on the enhancement of seeded tau aggregation by Aβ plaques has suggested a novel way for looking at the important, but unresolved, issue of the connection between Aβ and tau [3]. In the early 1990s, we began to collaborate with John and Virginia and have been friends ever since. John often stressed that our friendship transcended the fact that we were also scientific competitors. In 1997, we reported our most influential collaborative work, which showed the presence of α-synuclein in the Lewy pathology of Parkinson's disease (PD) and dementia with Lewy bodies [4]. PD is the second most common neurodegenerative disease. The following year, multiple system atrophy (MSA) was shown to be the third major synucleinopathy. This work followed closely on the heels of the demonstration that dominantly inherited mutation A53T in SNCA, the α-synuclein gene, causes PD. It reinforced the paradigm that rare cases of many neurodegenerative diseases are caused by mostly dominantly inherited mutations in the genes that encode the major components of the inclusions present in all cases of disease. Thus, fewer than 1% of cases of PD are caused by mutations in SNCA, but at autopsy over 95% of cases diagnosed as PD (including these inherited cases) have abundant α-synuclein inclusions in specific brain regions. This paradigm had previously been established for PRNP, the prion protein gene, and prion diseases, as well as for APP, the amyloid precursor protein gene, and AD. In 1998, the same was shown for tau, when mutations in MAPT, the tau gene, were found to cause inherited forms of frontotemporal dementia and Parkinsonism (FTDP-17T) with abundant tau inclusions. John co-authored one of three papers published in June of that year [5]. Identification of rare mutations in SNCA and MAPT in inherited cases of disease was conceptually important because it proved that dysfunction of α-synuclein and tau is sufficient to cause neurodegeneration. At a more practical level, these findings made it possible to produce transgenic mouse lines that develop abundant filamentous inclusions, be they made of tau or α-synuclein. John and Virginia were at the forefront of this undertaking [6-8]. Rather than being limited to investigate end-stage human diseases, this work opened the way to more mechanistic studies. Mouse lines were also important for experimental work on the propagation of tau and α-synuclein inclusions in brain [9, 10]. John and Virginia provided some of the best evidence in favour of the view that different conformers of assembled α-synuclein underlie Lewy body diseases and MSA [11]. These findings left open the question of what proteins the ubiquitinated inclusions of amyotrophic lateral sclerosis (ALS) and some forms of frontotemporal lobar degeneration (FTLD) are made. John and Virginia worked on this difficult problem for many years, with a combination of immunology and protein chemistry eventually resulting in their demonstration that TAR DNA-binding protein-43 (TDP-43) is the major component of these inclusions [12]. TDP-43 had not previously been linked to neurodegenerative disease. Inclusions are found in around 97% of cases of ALS and 50% of cases of FTLD. This discovery opened a new chapter in the study of neurodegenerative diseases. It confirmed that ALS and the most common form of FTLD belong to a clinicopathological spectrum and indicated that RNA mismetabolism may play an important role. This concept was subsequently extended through the demonstration that dysfunction of other RNA-binding proteins, such as fused in sarcoma (FUS), Ewing sarcoma RNA-binding protein-1 (EWSR1) and TATA-binding protein-associated factor-15 (TAF15) is central to some cases of ALS and FTLD. Mutations in TARDBP, the TDP-43 gene, cause a small number of inherited cases of FTLD with abundant TDP-43 inclusions, similar to what has been observed for PRNP in prion diseases, APP in AD, SNCA in PD and MAPT in FTDP-17T. Besides sporadic cases of FTLD, TDP-43 inclusions are also found in inherited cases caused by mutations in GRN (granulin gene), VCP (valosin-containing protein gene) and C9orf72 (chromosome 9 open reading frame 72). Like tau and α-synuclein, assembled TDP-43 from brain can induce the formation and spreading of inclusions [13]. Subtyping based on the appearance and distribution of inclusions has been particularly influential in the context of FTLD-TDP [14]. Moreover, it is now also recognized that a TDP-43 proteinopathy is commonly found in subjects who are over 80 years old. This entity has been named LATE (limbic-predominant age-related TDP-43 encephalopathy) by John and colleagues [15]. John had an attractive and whirlwind personality. He was a warm, cultured and urbane individual, with a well-developed sense of humour. We will miss him dearly. It is difficult to believe that we shall never again see John step up to the microphone and say ‘John Trojanowski, University of Pennsylvania’, before asking a pertinent question. To remember what John was like, watch the YouTube video film of his ALS Ice Bucket Challenge from August 2014: (https://www.youtube.com/watch?v=fdf12InZ-K8&feature=youtu.be).