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Fernandez A, Hoq MR, Hallinan GI, Li D, Bharath SR, Vago FS, Zhang X, Ozcan KA, Newell KL, Garringer HJ, Jiang W, Ghetti B, Vidal R. Cryo-EM structures of amyloid-β and tau filaments in Down syndrome. Nat Struct Mol Biol 2024; 31:903-909. [PMID: 38553642 PMCID: PMC11189299 DOI: 10.1038/s41594-024-01252-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 02/09/2024] [Indexed: 04/10/2024]
Abstract
Adult individuals with Down syndrome (DS) develop Alzheimer disease (AD). Whether there is a difference between AD in DS and AD regarding the structure of amyloid-β (Aβ) and tau filaments is unknown. Here we report the structure of Aβ and tau filaments from two DS brains. We found two Aβ40 filaments (types IIIa and IIIb) that differ from those previously reported in sporadic AD and two types of Aβ42 filaments (I and II) identical to those found in sporadic and familial AD. Tau filaments (paired helical filaments and straight filaments) were identical to those in AD, supporting the notion of a common mechanism through which amyloids trigger aggregation of tau. This knowledge is important for understanding AD in DS and assessing whether adults with DS could be included in AD clinical trials.
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Affiliation(s)
- Anllely Fernandez
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Md Rejaul Hoq
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, USA
| | - Grace I Hallinan
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Daoyi Li
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, USA
| | - Sakshibeedu R Bharath
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, USA
| | - Frank S Vago
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, USA
| | - Xiaoqi Zhang
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, USA
| | - Kadir A Ozcan
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, USA
| | - Kathy L Newell
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Holly J Garringer
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Wen Jiang
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN, USA.
| | - Bernardino Ghetti
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
| | - Ruben Vidal
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA.
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2
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Sun C, Huang P, Xu X, Vago FS, Li K, Klose T, Jiang XJ, Jiang W. The 2.6 Å Structure of a Tulane Virus Variant with Minor Mutations Leading to Receptor Change. Biomolecules 2024; 14:119. [PMID: 38254719 PMCID: PMC10813083 DOI: 10.3390/biom14010119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/12/2024] [Accepted: 01/15/2024] [Indexed: 01/24/2024] Open
Abstract
Human noroviruses (HuNoVs) are a major cause of acute gastroenteritis, contributing significantly to annual foodborne illness cases. However, studying these viruses has been challenging due to limitations in tissue culture techniques for over four decades. Tulane virus (TV) has emerged as a crucial surrogate for HuNoVs due to its close resemblance in amino acid composition and the availability of a robust cell culture system. Initially isolated from rhesus macaques in 2008, TV represents a novel Calicivirus belonging to the Recovirus genus. Its significance lies in sharing the same host cell receptor, histo-blood group antigen (HBGA), as HuNoVs. In this study, we introduce, through cryo-electron microscopy (cryo-EM), the structure of a specific TV variant (the 9-6-17 TV) that has notably lost its ability to bind to its receptor, B-type HBGA-a finding confirmed using an enzyme-linked immunosorbent assay (ELISA). These results offer a profound insight into the genetic modifications occurring in TV that are necessary for adaptation to cell culture environments. This research significantly contributes to advancing our understanding of the genetic changes that are pivotal to successful adaptation, shedding light on fundamental aspects of Calicivirus evolution.
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Affiliation(s)
- Chen Sun
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA (F.S.V.)
| | - Pengwei Huang
- Division of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Xueyong Xu
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA (F.S.V.)
| | - Frank S. Vago
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA (F.S.V.)
| | - Kunpeng Li
- School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Thomas Klose
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA (F.S.V.)
| | - Xi Jason Jiang
- Division of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Wen Jiang
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA (F.S.V.)
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3
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Lata K, Charles S, Mangala Prasad V. Advances in computational approaches to structure determination of alphaviruses and flaviviruses using cryo-electron microscopy. J Struct Biol 2023; 215:107993. [PMID: 37414374 DOI: 10.1016/j.jsb.2023.107993] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/15/2023] [Accepted: 07/03/2023] [Indexed: 07/08/2023]
Abstract
Advancements in the field of cryo-electron microscopy (cryo-EM) have greatly contributed to our current understanding of virus structures and life cycles. In this review, we discuss the application of single particle cryo-electron microscopy (EM) for the structure elucidation of small enveloped icosahedral viruses, namely, alpha- and flaviviruses. We focus on technical advances in cryo-EM data collection, image processing, three-dimensional reconstruction, and refinement strategies for obtaining high-resolution structures of these viruses. Each of these developments enabled new insights into the alpha- and flavivirus architecture, leading to a better understanding of their biology, pathogenesis, immune response, immunogen design, and therapeutic development.
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Affiliation(s)
- Kiran Lata
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Sylvia Charles
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Vidya Mangala Prasad
- Molecular Biophysics Unit, Indian Institute of Science, Bengaluru, Karnataka 560012, India; Center for Infectious Disease Research, Indian Institute of Science, Bengaluru, Karnataka 560012, India
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4
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Xia M, Vago F, Han L, Huang P, Nguyen L, Boons GJ, Klassen JS, Jiang W, Tan M. The αTSR Domain of Plasmodium Circumsporozoite Protein Bound Heparan Sulfates and Elicited High Titers of Sporozoite Binding Antibody After Displayed by Nanoparticles. Int J Nanomedicine 2023; 18:3087-3107. [PMID: 37312932 PMCID: PMC10259582 DOI: 10.2147/ijn.s406314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 05/31/2023] [Indexed: 06/15/2023] Open
Abstract
Introduction Malaria is a devastating infectious illness caused by protozoan Plasmodium parasites. The circumsporozoite protein (CSP) on Plasmodium sporozoites binds heparan sulfate proteoglycan (HSPG) receptors for liver invasion, a critical step for prophylactic and therapeutic interventions. Methods In this study, we characterized the αTSR domain that covers region III and the thrombospondin type-I repeat (TSR) of the CSP using various biochemical, glycobiological, bioengineering, and immunological approaches. Results We found for the first time that the αTSR bound heparan sulfate (HS) glycans through support by a fused protein, indicating that the αTSR is a key functional domain and thus a vaccine target. When the αTSR was fused to the S domain of norovirus VP1, the fusion protein self-assembled into uniform S60-αTSR nanoparticles. Three-dimensional structure reconstruction revealed that each nanoparticle consists of an S60 nanoparticle core and 60 surface displayed αTSR antigens. The nanoparticle displayed αTSRs retained the binding function to HS glycans, indicating that they maintained authentic conformations. Both tagged and tag-free S60-αTSR nanoparticles were produced via the Escherichia coli system at high yield by scalable approaches. They are highly immunogenic in mice, eliciting high titers of αTSR-specific antibody that bound specifically to the CSPs of Plasmodium falciparum sporozoites at high titer. Discussion and Conclusion Our data demonstrated that the αTSR is an important functional domain of the CSP. The S60-αTSR nanoparticle displaying multiple αTSR antigens is a promising vaccine candidate potentially against attachment and infection of Plasmodium parasites.
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Affiliation(s)
- Ming Xia
- Division of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Frank Vago
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Ling Han
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Pengwei Huang
- Division of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
| | - Linh Nguyen
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Geert-Jan Boons
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
- Department of Chemistry, University of Georgia, Athens, GA, USA
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, and Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, the Netherlands
| | - John S Klassen
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Wen Jiang
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Ming Tan
- Division of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
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5
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Dai M, Dong Z, Xu K, Cliff Zhang Q. CryoRes: Local Resolution Estimation of Cryo-EM Density Maps by Deep Learning. J Mol Biol 2023; 435:168059. [PMID: 36967040 DOI: 10.1016/j.jmb.2023.168059] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 03/15/2023] [Accepted: 03/21/2023] [Indexed: 04/03/2023]
Abstract
Recent progress in cryo-EM research has ignited a revolution in biological macromolecule structure determination. Resolution is an essential parameter for quality assessment of a cryo-EM density map, and it is known that resolution varies in different regions of a map. Currently available methods for local resolution estimation require manual adjustment of parameters and in some cases necessitate acquisition or de novo generation of so-called "half maps". Here, we developed CryoRes, a deep-learning algorithm to estimate local resolution directly from a single final cryo-EM density map, specifically by learning resolution-aware patterns of density map voxels through supervised training on a large dataset comprising 1,174 experimental cryo-EM density maps. CryoRes significantly outperforms all of the state-of-the-art competing resolution estimation methods, achieving an average RMSE of 2.26 Å for local resolution estimation relative to the currently most reliable FSC-based method blocres, yet requiring only the single final map as input. Further, CryoRes is able to generate a molecular mask for each map, with accuracy 12.12% higher than the masks generated by ResMap. CryoRes is ultra-fast, fully automatic, parameter-free, applicable to cryo-EM subtomogram data, and freely available at https://cryores.zhanglab.net.
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Hoq MR, Bharath SR, Hallinan GI, Fernandez A, Vago FS, Ozcan KA, Li D, Garringer HJ, Vidal R, Ghetti B, Jiang W. Cross-β helical filaments of Tau and TMEM106B in Gray and White Matter of Multiple System Tauopathy with presenile Dementia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.09.523314. [PMID: 36711790 PMCID: PMC9882095 DOI: 10.1101/2023.01.09.523314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Background The Microtubule-Associated Protein Tau (MAPT) is one of the proteins that are central to neurodegenerative diseases. The nature of intracellular tau aggregates is determined by the cell types whether neuronal or glial, the participating tau isoforms, and the structure of the amyloid filament. The transmembrane protein 106B (TMEM106B) has recently emerged as another significant player in neurodegeneration and aging. In the central nervous system, the composition of the gray and white matter differs considerably. The gray matter consists of nerve cell bodies, dendrites, unmyelinated axons, synaptic terminals, astrocytes, oligodendrocytes (satellite cells) and microglia. The white matter differs from the gray for the presence of axonal tracts as the only neuronal component and for the absence of nerve cell bodies, dendrites and synaptic terminals. Cryogenic electron microscopy (cryo-EM) studies have unveiled the structure of tau and TMEM106B, from the cerebral cortex, in several neurodegenerative diseases; however, whether tau and TMEM106B filaments from the gray and white matter share a common fold requires additional investigation. Methods We isolated tau and TMEM106B from the cerebral cortex and white matter of the frontal lobes of two individuals affected by multiple system tauopathy with presenile dementia (MSTD), a disease caused by the MAPT intron 10 mutation +3. We used immunostaining, biochemical, genetics and cryo-EM methods to characterize tau and TMEM106B. Results We determined that tau filaments in the gray and the white matter of MSTD individuals can induce tau aggregation and have identical AGD type 2 folds. TMEM106B amyloid filaments were also found in the gray and white matter of MSTD; the filament folds were identical in the two anatomical regions. Conclusions Our findings show for the first time that in MSTD two types of amyloid filaments extracted from the gray matter have identical folds to those extracted from the white matter. Whether in this genetic disorder there is a relationship in the pathogenesis of the tau and TMEM106B filaments, remains to be determined. Furthermore, additional studies are needed for other proteins and other neurodegenerative diseases to establish whether filaments extracted from the gray and white matter would have identical folds.
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Hallinan GI, Ozcan KA, Hoq MR, Cracco L, Vago FS, Bharath SR, Li D, Jacobsen M, Doud EH, Mosley AL, Fernandez A, Garringer HJ, Jiang W, Ghetti B, Vidal R. Cryo-EM structures of prion protein filaments from Gerstmann-Sträussler-Scheinker disease. Acta Neuropathol 2022; 144:509-520. [PMID: 35819518 PMCID: PMC9381446 DOI: 10.1007/s00401-022-02461-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 06/23/2022] [Accepted: 06/23/2022] [Indexed: 12/28/2022]
Abstract
Prion protein (PrP) aggregation and formation of PrP amyloid (APrP) are central events in the pathogenesis of prion diseases. In the dominantly inherited prion protein amyloidosis known as Gerstmann-Sträussler-Scheinker (GSS) disease, plaques made of PrP amyloid are present throughout the brain. The c.593t > c mutation in the prion protein gene (PRNP) results in a phenylalanine to serine amino acid substitution at PrP residue 198 (F198S) and causes the most severe amyloidosis among GSS variants. It has been shown that neurodegeneration in this disease is associated with the presence of extracellular APrP plaques and neuronal intracytoplasmic Tau inclusions, that have been shown to contain paired helical filaments identical to those found in Alzheimer disease. Using cryogenic electron microscopy (cryo-EM), we determined for the first time the structures of filaments of human APrP, isolated post-mortem from the brain of two symptomatic PRNP F198S mutation carriers. We report that in GSS (F198S) APrP filaments are composed of dimeric, trimeric and tetrameric left-handed protofilaments with their protomers sharing a common protein fold. The protomers in the cross-β spines consist of 62 amino acids and span from glycine 80 to phenylalanine 141, adopting a previously unseen spiral fold with a thicker outer layer and a thinner inner layer. Each protomer comprises nine short β-strands, with the β1 and β8 strands, as well as the β4 and β9 strands, forming a steric zipper. The data obtained by cryo-EM provide insights into the structural complexity of the PrP filament in a dominantly inherited human PrP amyloidosis. The novel findings highlight the urgency of extending our knowledge of the filaments' structures that may underlie distinct clinical and pathologic phenotypes of human neurodegenerative diseases.
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Affiliation(s)
- Grace I. Hallinan
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 635 Barnhill Dr., Indianapolis, IN 46202 USA
| | - Kadir A. Ozcan
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47906 USA
| | - Md Rejaul Hoq
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47906 USA
| | - Laura Cracco
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 635 Barnhill Dr., Indianapolis, IN 46202 USA
| | - Frank S. Vago
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47906 USA
| | - Sakshibeedu R. Bharath
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47906 USA
| | - Daoyi Li
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47906 USA
| | - Max Jacobsen
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 635 Barnhill Dr., Indianapolis, IN 46202 USA
| | - Emma H. Doud
- Center for Proteome Analysis and Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN 46202 USA
| | - Amber L. Mosley
- Center for Proteome Analysis and Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN 46202 USA
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202 USA
| | - Anllely Fernandez
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 635 Barnhill Dr., Indianapolis, IN 46202 USA
| | - Holly J. Garringer
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 635 Barnhill Dr., Indianapolis, IN 46202 USA
| | - Wen Jiang
- Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, IN 47906 USA
| | - Bernardino Ghetti
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 635 Barnhill Dr., Indianapolis, IN 46202 USA
| | - Ruben Vidal
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 635 Barnhill Dr., Indianapolis, IN 46202 USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202 USA
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Burton-Smith RN, Murata K. Cryo-Electron Microscopy of the Giant Viruses. Microscopy (Oxf) 2021; 70:477-486. [PMID: 34490462 DOI: 10.1093/jmicro/dfab036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/26/2021] [Accepted: 08/30/2021] [Indexed: 11/12/2022] Open
Abstract
High resolution study of the giant viruses presents one of the latest challenges in cryo-electron microscopy of viruses. Too small for light microscopy, but too large for easy study at high resolution by electron microscopy, they range in size from ~0.2-2 μm, from high symmetry icosahedral viruses such as Paramecium burseria Chlorella virus 1 to asymmetric forms like Tupanvirus or Pithovirus. To attain high resolution, two strategies exist to study these large viruses by cryo-EM: firstly, increasing the acceleration voltage of the electron microscope to improve sample penetration and overcome the limitations imposed by electro-optical physics at lower voltages, and secondly the method of "block-based reconstruction" pioneered by Michael G. Rossmann and his collaborators, which resolves the latter limitation through an elegant leveraging of high symmetry, but cannot overcome sample penetration limitations. In addition, more recent advances in both computational capacity and image processing also yield assistance in studying the giant viruses. Especially, the inclusion of Ewald sphere correction can provide large improvements in attainable resolutions for 300 kV electron microscopes. Despite this, the study of giant viruses remains a significant challenge.
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Affiliation(s)
- Raymond N Burton-Smith
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan.,National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan
| | - Kazuyoshi Murata
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Aichi, Japan.,National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi, Japan.,Department of Physiological Sciences, School of Life Science, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, Aichi, Japan
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Structure of Tau filaments in Prion protein amyloidoses. Acta Neuropathol 2021; 142:227-241. [PMID: 34128081 PMCID: PMC8270882 DOI: 10.1007/s00401-021-02336-w] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/08/2021] [Accepted: 06/09/2021] [Indexed: 12/14/2022]
Abstract
In human neurodegenerative diseases associated with the intracellular aggregation of Tau protein, the ordered cores of Tau filaments adopt distinct folds. Here, we analyze Tau filaments isolated from the brain of individuals affected by Prion-Protein cerebral amyloid angiopathy (PrP-CAA) with a nonsense mutation in the PRNP gene that leads to early termination of translation of PrP (Q160Ter or Q160X), and Gerstmann–Sträussler–Scheinker (GSS) disease, with a missense mutation in the PRNP gene that leads to an amino acid substitution at residue 198 (F198S) of PrP. The clinical and neuropathologic phenotypes associated with these two mutations in PRNP are different; however, the neuropathologic analyses of these two genetic variants have consistently shown the presence of numerous neurofibrillary tangles (NFTs) made of filamentous Tau aggregates in neurons. We report that Tau filaments in PrP-CAA (Q160X) and GSS (F198S) are composed of 3-repeat and 4-repeat Tau isoforms, having a striking similarity to NFTs in Alzheimer disease (AD). In PrP-CAA (Q160X), Tau filaments are made of both paired helical filaments (PHFs) and straight filaments (SFs), while in GSS (F198S), only PHFs were found. Mass spectrometry analyses of Tau filaments extracted from PrP-CAA (Q160X) and GSS (F198S) brains show the presence of post-translational modifications that are comparable to those seen in Tau aggregates from AD. Cryo-EM analysis reveals that the atomic models of the Tau filaments obtained from PrP-CAA (Q160X) and GSS (F198S) are identical to those of the Tau filaments from AD, and are therefore distinct from those of Pick disease, chronic traumatic encephalopathy, and corticobasal degeneration. Our data support the hypothesis that in the presence of extracellular amyloid deposits and regardless of the primary amino acid sequence of the amyloid protein, similar molecular mechanisms are at play in the formation of identical Tau filaments.
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