RESUMO
A recent case report described an individual who was a homozygous carrier of the APOE3 Christchurch (APOE3ch) mutation and resistant to autosomal dominant Alzheimer's Disease (AD) caused by a PSEN1-E280A mutation. Whether APOE3ch contributed to the protective effect remains unclear. We generated a humanized APOE3ch knock-in mouse and crossed it to an amyloid-ß (Aß) plaque-depositing model. We injected AD-tau brain extract to investigate tau seeding and spreading in the presence or absence of amyloid. Similar to the case report, APOE3ch expression resulted in peripheral dyslipidemia and a marked reduction in plaque-associated tau pathology. Additionally, we observed decreased amyloid response and enhanced microglial response around plaques. We also demonstrate increased myeloid cell phagocytosis and degradation of tau aggregates linked to weaker APOE3ch binding to heparin sulfate proteoglycans. APOE3ch influences the microglial response to Aß plaques, which suppresses Aß-induced tau seeding and spreading. The results reveal new possibilities to target Aß-induced tauopathy.
Assuntos
Doença de Alzheimer , Peptídeos beta-Amiloides , Apolipoproteína E3 , Proteínas tau , Animais , Humanos , Camundongos , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Proteínas Amiloidogênicas/metabolismo , Apolipoproteína E3/genética , Apolipoproteína E3/metabolismo , Encéfalo/metabolismo , Modelos Animais de Doenças , Camundongos Transgênicos , Microglia/metabolismo , Placa Amiloide/metabolismo , Proteínas tau/genética , Proteínas tau/metabolismo , Relatos de Casos como AssuntoRESUMO
Tauopathies are age-associated neurodegenerative diseases whose mechanistic underpinnings remain elusive, partially due to a lack of appropriate human models. Here, we engineered human induced pluripotent stem cell (hiPSC)-derived neuronal lines to express 4R Tau and 4R Tau carrying the P301S MAPT mutation when differentiated into neurons. 4R-P301S neurons display progressive Tau inclusions upon seeding with Tau fibrils and recapitulate features of tauopathy phenotypes including shared transcriptomic signatures, autophagic body accumulation, and reduced neuronal activity. A CRISPRi screen of genes associated with Tau pathobiology identified over 500 genetic modifiers of seeding-induced Tau propagation, including retromer VPS29 and genes in the UFMylation cascade. In progressive supranuclear palsy (PSP) and Alzheimer's Disease (AD) brains, the UFMylation cascade is altered in neurofibrillary-tangle-bearing neurons. Inhibiting the UFMylation cascade in vitro and in vivo suppressed seeding-induced Tau propagation. This model provides a robust platform to identify novel therapeutic strategies for 4R tauopathy.
Assuntos
Células-Tronco Pluripotentes Induzidas , Neurônios , Tauopatias , Proteínas tau , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Proteínas tau/metabolismo , Tauopatias/metabolismo , Tauopatias/patologia , Neurônios/metabolismo , Neurônios/patologia , Animais , Camundongos , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Doença de Alzheimer/genética , Encéfalo/metabolismo , Encéfalo/patologia , Paralisia Supranuclear Progressiva/metabolismo , Paralisia Supranuclear Progressiva/patologia , Paralisia Supranuclear Progressiva/genética , Diferenciação Celular , Mutação , AutofagiaRESUMO
Although women are at higher risk for Alzheimer's disease and other tauopathies, the underlying mechanisms are unclear. In this issue of Cell, Yan et al. show that aberrantly high activity of X-linked USP11 deubiquitinase in women impairs clearance of tau, the principal component of neurofibrillary tangles in Alzheimer's disease.
Assuntos
Doença de Alzheimer , Tauopatias , Doença de Alzheimer/genética , Enzimas Desubiquitinantes , Feminino , Humanos , Emaranhados Neurofibrilares , Tioléster Hidrolases , Proteínas tau/genéticaRESUMO
Tau (MAPT) drives neuronal dysfunction in Alzheimer disease (AD) and other tauopathies. To dissect the underlying mechanisms, we combined an engineered ascorbic acid peroxidase (APEX) approach with quantitative affinity purification mass spectrometry (AP-MS) followed by proximity ligation assay (PLA) to characterize Tau interactomes modified by neuronal activity and mutations that cause frontotemporal dementia (FTD) in human induced pluripotent stem cell (iPSC)-derived neurons. We established interactions of Tau with presynaptic vesicle proteins during activity-dependent Tau secretion and mapped the Tau-binding sites to the cytosolic domains of integral synaptic vesicle proteins. We showed that FTD mutations impair bioenergetics and markedly diminished Tau's interaction with mitochondria proteins, which were downregulated in AD brains of multiple cohorts and correlated with disease severity. These multimodal and dynamic Tau interactomes with exquisite spatial resolution shed light on Tau's role in neuronal function and disease and highlight potential therapeutic targets to block Tau-mediated pathogenesis.
Assuntos
Mitocôndrias/metabolismo , Degeneração Neural/metabolismo , Mapas de Interação de Proteínas , Sinapses/metabolismo , Proteínas tau/metabolismo , Doença de Alzheimer/genética , Aminoácidos/metabolismo , Biotinilação , Encéfalo/metabolismo , Encéfalo/patologia , Núcleo Celular/metabolismo , Progressão da Doença , Metabolismo Energético , Demência Frontotemporal/genética , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Proteínas Mutantes/metabolismo , Mutação/genética , Degeneração Neural/patologia , Neurônios/metabolismo , Ligação Proteica , Domínios Proteicos , Proteômica , Índice de Gravidade de Doença , Frações Subcelulares/metabolismo , Tauopatias/genética , Proteínas tau/químicaRESUMO
Although women experience significantly higher tau burden and increased risk for Alzheimer's disease (AD) than men, the underlying mechanism for this vulnerability has not been explained. Here, we demonstrate through in vitro and in vivo models, as well as human AD brain tissue, that X-linked ubiquitin specific peptidase 11 (USP11) augments pathological tau aggregation via tau deubiquitination initiated at lysine-281. Removal of ubiquitin provides access for enzymatic tau acetylation at lysines 281 and 274. USP11 escapes complete X-inactivation, and female mice and people both exhibit higher USP11 levels than males. Genetic elimination of usp11 in a tauopathy mouse model preferentially protects females from acetylated tau accumulation, tau pathology, and cognitive impairment. USP11 levels also strongly associate positively with tau pathology in females but not males. Thus, inhibiting USP11-mediated tau deubiquitination may provide an effective therapeutic opportunity to protect women from increased vulnerability to AD and other tauopathies.
Assuntos
Doença de Alzheimer , Tauopatias , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Caracteres Sexuais , Tauopatias/genética , Tauopatias/patologia , Tioléster Hidrolases/genética , Proteases Específicas de Ubiquitina , Proteínas tau/genéticaRESUMO
Greater understanding of the events preceding neurodegeneration is needed to design effective preventive and therapeutic strategies. In this issue of Cell, Bowles et al. (2021) report cerebral organoids that reveal early events in frontotemporal dementia pathogenesis due to mutations in microtubule-associated protein tau (MAPT), shedding light on a novel mechanism involving abnormal splicing and glutamate signaling.
Assuntos
Demência Frontotemporal , Organoides , Humanos , Mutação , Proteínas tau/genéticaRESUMO
Traumatic brain injury (TBI) is the largest non-genetic, non-aging related risk factor for Alzheimer's disease (AD). We report here that TBI induces tau acetylation (ac-tau) at sites acetylated also in human AD brain. This is mediated by S-nitrosylated-GAPDH, which simultaneously inactivates Sirtuin1 deacetylase and activates p300/CBP acetyltransferase, increasing neuronal ac-tau. Subsequent tau mislocalization causes neurodegeneration and neurobehavioral impairment, and ac-tau accumulates in the blood. Blocking GAPDH S-nitrosylation, inhibiting p300/CBP, or stimulating Sirtuin1 all protect mice from neurodegeneration, neurobehavioral impairment, and blood and brain accumulation of ac-tau after TBI. Ac-tau is thus a therapeutic target and potential blood biomarker of TBI that may represent pathologic convergence between TBI and AD. Increased ac-tau in human AD brain is further augmented in AD patients with history of TBI, and patients receiving the p300/CBP inhibitors salsalate or diflunisal exhibit decreased incidence of AD and clinically diagnosed TBI.
Assuntos
Doença de Alzheimer/etiologia , Doença de Alzheimer/prevenção & controle , Lesões Encefálicas Traumáticas/complicações , Neuroproteção , Proteínas tau/metabolismo , Acetilação , Doença de Alzheimer/metabolismo , Animais , Anti-Inflamatórios não Esteroides/uso terapêutico , Biomarcadores/sangue , Biomarcadores/metabolismo , Lesões Encefálicas Traumáticas/metabolismo , Linhagem Celular , Diflunisal/uso terapêutico , Feminino , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora) , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Salicilatos/uso terapêutico , Sirtuína 1/metabolismo , Fatores de Transcrição de p300-CBP/antagonistas & inibidores , Fatores de Transcrição de p300-CBP/metabolismo , Proteínas tau/sangueRESUMO
Frontotemporal dementia (FTD) because of MAPT mutation causes pathological accumulation of tau and glutamatergic cortical neuronal death by unknown mechanisms. We used human induced pluripotent stem cell (iPSC)-derived cerebral organoids expressing tau-V337M and isogenic corrected controls to discover early alterations because of the mutation that precede neurodegeneration. At 2 months, mutant organoids show upregulated expression of MAPT, glutamatergic signaling pathways, and regulators, including the RNA-binding protein ELAVL4, and increased stress granules. Over the following 4 months, mutant organoids accumulate splicing changes, disruption of autophagy function, and build-up of tau and P-tau-S396. By 6 months, tau-V337M organoids show specific loss of glutamatergic neurons as seen in individuals with FTD. Mutant neurons are susceptible to glutamate toxicity, which can be rescued pharmacologically by the PIKFYVE kinase inhibitor apilimod. Our results demonstrate a sequence of events that precede neurodegeneration, revealing molecular pathways associated with glutamate signaling as potential targets for therapeutic intervention in FTD.
Assuntos
Cérebro/patologia , Proteína Semelhante a ELAV 4/genética , Ácido Glutâmico/metabolismo , Mutação/genética , Neurônios/patologia , Organoides/metabolismo , Splicing de RNA/genética , Proteínas tau/genética , Autofagia/efeitos dos fármacos , Autofagia/genética , Biomarcadores/metabolismo , Padronização Corporal/efeitos dos fármacos , Padronização Corporal/genética , Morte Celular/efeitos dos fármacos , Linhagem Celular , Humanos , Hidrazonas/farmacologia , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Morfolinas/farmacologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Organoides/efeitos dos fármacos , Organoides/ultraestrutura , Fosforilação/efeitos dos fármacos , Pirimidinas/farmacologia , Splicing de RNA/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Grânulos de Estresse/efeitos dos fármacos , Grânulos de Estresse/metabolismo , Sinapses/metabolismo , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/genéticaRESUMO
Tau aggregation into insoluble filaments is the defining pathological hallmark of tauopathies. However, it is not known what controls the formation and templated seeding of strain-specific structures associated with individual tauopathies. Here, we use cryo-electron microscopy (cryo-EM) to determine the structures of tau filaments from corticobasal degeneration (CBD) human brain tissue. Cryo-EM and mass spectrometry of tau filaments from CBD reveal that this conformer is heavily decorated with posttranslational modifications (PTMs), enabling us to map PTMs directly onto the structures. By comparing the structures and PTMs of tau filaments from CBD and Alzheimer's disease, it is found that ubiquitination of tau can mediate inter-protofilament interfaces. We propose a structure-based model in which cross-talk between PTMs influences tau filament structure, contributing to the structural diversity of tauopathy strains. Our approach establishes a framework for further elucidating the relationship between the structures of polymorphic fibrils, including their PTMs, and neurodegenerative disease.
Assuntos
Processamento de Proteína Pós-Traducional , Tauopatias/metabolismo , Proteínas tau/química , Idoso , Microscopia Crioeletrônica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/patologia , Tauopatias/patologia , Proteínas tau/metabolismoRESUMO
To elucidate the role of Tau isoforms and post-translational modification (PTM) stoichiometry in Alzheimer's disease (AD), we generated a high-resolution quantitative proteomics map of 95 PTMs on multiple isoforms of Tau isolated from postmortem human tissue from 49 AD and 42 control subjects. Although Tau PTM maps reveal heterogeneity across subjects, a subset of PTMs display high occupancy and frequency for AD, suggesting importance in disease. Unsupervised analyses indicate that PTMs occur in an ordered manner, leading to Tau aggregation. The processive addition and minimal set of PTMs associated with seeding activity was further defined by analysis of size-fractionated Tau. To summarize, features in the Tau protein critical for disease intervention at different stages of disease are identified, including enrichment of 0N and 4R isoforms, underrepresentation of the C terminus, an increase in negative charge in the proline-rich region (PRR), and a decrease in positive charge in the microtubule binding domain (MBD).
Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Processamento de Proteína Pós-Traducional , Proteínas tau/metabolismo , Estudos de Casos e Controles , Estudos de Coortes , Progressão da Doença , Humanos , Análise de Componente Principal , Isoformas de Proteínas/metabolismoRESUMO
Most common neurodegenerative diseases feature deposition of protein amyloids and degeneration of brain networks. Amyloids are ordered protein assemblies that can act as templates for their own replication through monomer addition. Evidence suggests that this characteristic may underlie the progression of pathology in neurodegenerative diseases. Many different amyloid proteins, including Aß, tau, and α-synuclein, exhibit properties similar to those of infectious prion protein in experimental systems: discrete and self-replicating amyloid structures, transcellular propagation of aggregation, and transmissible neuropathology. This review discusses the contribution of prion phenomena and transcellular propagation to the progression of pathology in common neurodegenerative diseases such as Alzheimer's and Parkinson's. It reviews fundamental events such as cell entry, amplification, and transcellular movement. It also discusses amyloid strains, which produce distinct patterns of neuropathology and spread through the nervous system. These concepts may impact the development of new diagnostic and therapeutic strategies.
Assuntos
Doenças Neurodegenerativas/metabolismo , Agregação Patológica de Proteínas , Amiloide , Animais , Humanos , Doenças Neurodegenerativas/etiologia , Doenças Neurodegenerativas/patologia , Proteínas tauRESUMO
Alzheimer disease (AD) is a heterogeneous disease with a complex pathobiology. The presence of extracellular ß-amyloid deposition as neuritic plaques and intracellular accumulation of hyperphosphorylated tau as neurofibrillary tangles remains the primary neuropathologic criteria for AD diagnosis. However, a number of recent fundamental discoveries highlight important pathological roles for other critical cellular and molecular processes. Despite this, no disease-modifying treatment currently exists, and numerous phase 3 clinical trials have failed to demonstrate benefits. Here, we review recent advances in our understanding of AD pathobiology and discuss current treatment strategies, highlighting recent clinical trials and opportunities for developing future disease-modifying therapies.
Assuntos
Doença de Alzheimer , Peptídeos beta-Amiloides , Placa Amiloide/metabolismo , Proteínas tau , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Doença de Alzheimer/terapia , Vacinas contra Alzheimer/farmacologia , Peptídeos beta-Amiloides/antagonistas & inibidores , Peptídeos beta-Amiloides/metabolismo , Animais , Apolipoproteínas E/antagonistas & inibidores , Apolipoproteínas E/metabolismo , Ensaios Clínicos como Assunto , Humanos , Camundongos , Proteínas tau/antagonistas & inibidores , Proteínas tau/metabolismoRESUMO
Over 40% of the human genome is composed of retrotransposons, DNA species that hold the potential to replicate via an RNA intermediate and are evolutionarily related to retroviruses. Retrotransposons are most studied for their ability to jump within a genome, which can cause DNA damage and novel insertional mutations. Retrotransposon-encoded products, including viral-like proteins, double-stranded RNAs, and extrachromosomal circular DNAs, can also be potent activators of the innate immune system. A growing body of evidence suggests that retrotransposons are activated in age-related neurodegenerative disorders and that such activation causally contributes to neurotoxicity. Here we provide an overview of retrotransposon biology and outline evidence of retrotransposon activation in age-related neurodegenerative disorders, with an emphasis on those involving TAR-DNA binding protein-43 (TDP-43) and tau. Studies to date provide the basis for ongoing clinical trials and hold promise for innovative strategies to ameliorate the adverse effects of retrotransposon dysregulation in neurodegenerative disorders.
Assuntos
Envelhecimento , Retrovirus Endógenos , Doenças Neurodegenerativas , Retroelementos , Humanos , Doenças Neurodegenerativas/genética , Retroelementos/genética , Retrovirus Endógenos/genética , Animais , Envelhecimento/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas tau/genética , Proteínas tau/metabolismoRESUMO
Intermediate species in the assembly of amyloid filaments are believed to play a central role in neurodegenerative diseases and may constitute important targets for therapeutic intervention1,2. However, structural information about intermediate species has been scarce and the molecular mechanisms by which amyloids assemble remain largely unknown. Here we use time-resolved cryogenic electron microscopy to study the in vitro assembly of recombinant truncated tau (amino acid residues 297-391) into paired helical filaments of Alzheimer's disease or into filaments of chronic traumatic encephalopathy3. We report the formation of a shared first intermediate amyloid filament, with an ordered core comprising residues 302-316. Nuclear magnetic resonance indicates that the same residues adopt rigid, ß-strand-like conformations in monomeric tau. At later time points, the first intermediate amyloid disappears and we observe many different intermediate amyloid filaments, with structures that depend on the reaction conditions. At the end of both assembly reactions, most intermediate amyloids disappear and filaments with the same ordered cores as those from human brains remain. Our results provide structural insights into the processes of primary and secondary nucleation of amyloid assembly, with implications for the design of new therapies.
Assuntos
Doença de Alzheimer , Amiloide , Encefalopatia Traumática Crônica , Emaranhados Neurofibrilares , Proteínas tau , Humanos , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Amiloide/química , Amiloide/metabolismo , Amiloide/ultraestrutura , Encefalopatia Traumática Crônica/metabolismo , Encefalopatia Traumática Crônica/patologia , Microscopia Crioeletrônica , Emaranhados Neurofibrilares/química , Emaranhados Neurofibrilares/metabolismo , Emaranhados Neurofibrilares/ultraestrutura , Proteínas tau/química , Proteínas tau/metabolismo , Proteínas tau/ultraestrutura , Ressonância Magnética Nuclear Biomolecular , Conformação Proteica , Fatores de TempoRESUMO
A defining pathological feature of most neurodegenerative diseases is the assembly of proteins into amyloid that form disease-specific structures1. In Alzheimer's disease, this is characterized by the deposition of ß-amyloid and tau with disease-specific conformations. The in situ structure of amyloid in the human brain is unknown. Here, using cryo-fluorescence microscopy-targeted cryo-sectioning, cryo-focused ion beam-scanning electron microscopy lift-out and cryo-electron tomography, we determined in-tissue architectures of ß-amyloid and tau pathology in a postmortem Alzheimer's disease donor brain. ß-amyloid plaques contained a mixture of fibrils, some of which were branched, and protofilaments, arranged in parallel arrays and lattice-like structures. Extracellular vesicles and cuboidal particles defined the non-amyloid constituents of ß-amyloid plaques. By contrast, tau inclusions formed parallel clusters of unbranched filaments. Subtomogram averaging a cluster of 136 tau filaments in a single tomogram revealed the polypeptide backbone conformation and filament polarity orientation of paired helical filaments within tissue. Filaments within most clusters were similar to each other, but were different between clusters, showing amyloid heterogeneity that is spatially organized by subcellular location. The in situ structural approaches outlined here for human donor tissues have applications to a broad range of neurodegenerative diseases.
Assuntos
Doença de Alzheimer , Peptídeos beta-Amiloides , Encéfalo , Microscopia Crioeletrônica , Tomografia com Microscopia Eletrônica , Placa Amiloide , Proteínas tau , Humanos , Masculino , Camundongos , Doença de Alzheimer/patologia , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/metabolismo , Peptídeos beta-Amiloides/ultraestrutura , Autopsia , Encéfalo/metabolismo , Encéfalo/patologia , Encéfalo/ultraestrutura , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/química , Vesículas Extracelulares/ultraestrutura , Placa Amiloide/metabolismo , Placa Amiloide/patologia , Placa Amiloide/química , Placa Amiloide/ultraestrutura , Proteínas tau/química , Proteínas tau/metabolismo , Proteínas tau/ultraestruturaRESUMO
Several genetic risk factors for Alzheimer's disease implicate genes involved in lipid metabolism and many of these lipid genes are highly expressed in glial cells1. However, the relationship between lipid metabolism in glia and Alzheimer's disease pathology remains poorly understood. Through single-nucleus RNA sequencing of brain tissue in Alzheimer's disease, we have identified a microglial state defined by the expression of the lipid droplet-associated enzyme ACSL1 with ACSL1-positive microglia being most abundant in patients with Alzheimer's disease having the APOE4/4 genotype. In human induced pluripotent stem cell-derived microglia, fibrillar Aß induces ACSL1 expression, triglyceride synthesis and lipid droplet accumulation in an APOE-dependent manner. Additionally, conditioned media from lipid droplet-containing microglia lead to Tau phosphorylation and neurotoxicity in an APOE-dependent manner. Our findings suggest a link between genetic risk factors for Alzheimer's disease with microglial lipid droplet accumulation and neurotoxic microglia-derived factors, potentially providing therapeutic strategies for Alzheimer's disease.
Assuntos
Doença de Alzheimer , Apolipoproteína E4 , Gotículas Lipídicas , Microglia , Animais , Feminino , Humanos , Masculino , Camundongos , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Apolipoproteína E4/genética , Apolipoproteína E4/metabolismo , Células-Tronco Pluripotentes Induzidas/citologia , Gotículas Lipídicas/metabolismo , Gotículas Lipídicas/patologia , Microglia/citologia , Microglia/metabolismo , Microglia/patologia , Triglicerídeos , Proteínas tau , Meios de Cultivo Condicionados , Fosforilação , Predisposição Genética para DoençaRESUMO
Phase separation can concentrate biomolecules and accelerate reactions. However, the mechanisms and principles connecting this mesoscale organization to signaling dynamics are difficult to dissect because of the pleiotropic effects associated with disrupting endogenous condensates. To address this limitation, we engineered new phosphorylation reactions within synthetic condensates. We generally found increased activity and broadened kinase specificity. Phosphorylation dynamics within condensates were rapid and could drive cell-cycle-dependent localization changes. High client concentration within condensates was important but not the main factor for efficient phosphorylation. Rather, the availability of many excess client-binding sites together with a flexible scaffold was crucial. Phosphorylation within condensates was also modulated by changes in macromolecular crowding. Finally, the phosphorylation of the Alzheimer's-disease-associated protein Tau by cyclin-dependent kinase 2 was accelerated within condensates. Thus, condensates enable new signaling connections and can create sensors that respond to the biophysical properties of the cytoplasm.
Assuntos
Transdução de Sinais , Proteínas tau , Quinase 2 Dependente de Ciclina/metabolismo , Citoplasma/metabolismo , Humanos , Substâncias Macromoleculares/metabolismo , Proteínas tau/genética , Proteínas tau/metabolismoRESUMO
Protein folding in the cell relies on the orchestrated action of conserved families of molecular chaperones, the Hsp70 and Hsp90 systems. Hsp70 acts early and Hsp90 late in the folding path, yet the molecular basis of this timing is enigmatic, mainly because the substrate specificity of Hsp90 is poorly understood. Here, we obtained a structural model of Hsp90 in complex with its natural disease-associated substrate, the intrinsically disordered Tau protein. Hsp90 binds to a broad region in Tau that includes the aggregation-prone repeats. Complementarily, a 106-Å-long substrate-binding interface in Hsp90 enables many low-affinity contacts. This allows recognition of scattered hydrophobic residues in late folding intermediates that remain after early burial of the Hsp70 sites. Our model resolves the paradox of how Hsp90 specifically selects for late folding intermediates but also for some intrinsically disordered proteins-through the eyes of Hsp90 they look the same.
Assuntos
Proteínas tau/química , Doença de Alzheimer/tratamento farmacológico , Sequência de Aminoácidos , Proteínas de Choque Térmico HSP90/química , Proteínas de Choque Térmico HSP90/metabolismo , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Dobramento de Proteína , Espalhamento a Baixo Ângulo , Difração de Raios X , Proteínas tau/metabolismoRESUMO
Extracellular deposition of amyloid-ß as neuritic plaques and intracellular accumulation of hyperphosphorylated, aggregated tau as neurofibrillary tangles are two of the characteristic hallmarks of Alzheimer's disease1,2. The regional progression of brain atrophy in Alzheimer's disease highly correlates with tau accumulation but not amyloid deposition3-5, and the mechanisms of tau-mediated neurodegeneration remain elusive. Innate immune responses represent a common pathway for the initiation and progression of some neurodegenerative diseases. So far, little is known about the extent or role of the adaptive immune response and its interaction with the innate immune response in the presence of amyloid-ß or tau pathology6. Here we systematically compared the immunological milieux in the brain of mice with amyloid deposition or tau aggregation and neurodegeneration. We found that mice with tauopathy but not those with amyloid deposition developed a unique innate and adaptive immune response and that depletion of microglia or T cells blocked tau-mediated neurodegeneration. Numbers of T cells, especially those of cytotoxic T cells, were markedly increased in areas with tau pathology in mice with tauopathy and in the Alzheimer's disease brain. T cell numbers correlated with the extent of neuronal loss, and the cells dynamically transformed their cellular characteristics from activated to exhausted states along with unique TCR clonal expansion. Inhibition of interferon-γ and PDCD1 signalling both significantly ameliorated brain atrophy. Our results thus reveal a tauopathy- and neurodegeneration-related immune hub involving activated microglia and T cell responses, which could serve as therapeutic targets for preventing neurodegeneration in Alzheimer's disease and primary tauopathies.