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Todd TW, Islam NN, Cook CN, Caulfield TR, Petrucelli L. Cryo-EM structures of pathogenic fibrils and their impact on neurodegenerative disease research. Neuron 2024; 112:2269-2288. [PMID: 38834068 PMCID: PMC11257806 DOI: 10.1016/j.neuron.2024.05.012] [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: 08/22/2023] [Revised: 03/13/2024] [Accepted: 05/09/2024] [Indexed: 06/06/2024]
Abstract
Neurodegenerative diseases are commonly associated with the formation of aberrant protein aggregates within the brain, and ultrastructural analyses have revealed that the proteins within these inclusions often assemble into amyloid filaments. Cryoelectron microscopy (cryo-EM) has emerged as an effective method for determining the near-atomic structure of these disease-associated filamentous proteins, and the resulting structures have revolutionized the way we think about aberrant protein aggregation and propagation during disease progression. These structures have also revealed that individual fibril conformations may dictate different disease conditions, and this newfound knowledge has improved disease modeling in the lab and advanced the ongoing pursuit of clinical tools capable of distinguishing and targeting different pathogenic entities within living patients. In this review, we summarize some of the recently developed cryo-EM structures of ex vivo α-synuclein, tau, β-amyloid (Aβ), TAR DNA-binding protein 43 (TDP-43), and transmembrane protein 106B (TMEM106B) fibrils and discuss how these structures are being leveraged toward mechanistic research and therapeutic development.
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Affiliation(s)
- Tiffany W Todd
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Naeyma N Islam
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Casey N Cook
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Neurobiology of Disease Graduate Program, Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
| | | | - Leonard Petrucelli
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Neurobiology of Disease Graduate Program, Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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2
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Suri K, Ramesh M, Bhandari M, Gupta V, Kumar V, Govindaraju T, Murugan NA. Role of Amyloidogenic and Non-Amyloidogenic Protein Spaces in Neurodegenerative Diseases and their Mitigation Using Theranostic Agents. Chembiochem 2024; 25:e202400224. [PMID: 38668376 DOI: 10.1002/cbic.202400224] [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: 03/11/2024] [Revised: 04/23/2024] [Indexed: 06/15/2024]
Abstract
Neurodegenerative diseases (NDDs) refer to a complex heterogeneous group of diseases which are associated with the accumulation of amyloid fibrils or plaques in the brain leading to progressive loss of neuronal functions. Alzheimer's disease is one of the major NDD responsible for 60-80 % of all dementia cases. Currently, there are no curative or disease-reversing/modifying molecules for many of the NDDs except a few such as donepezil, rivastigmine, galantamine, carbidopa and levodopa which treat the disease-associated symptoms. Similarly, there are very few FDA-approved tracers such as flortaucipir (Tauvid) for tau fibril imaging and florbetaben (Neuraceq), flutemetamol (Vizamyl), and florbetapir (Amyvid) for amyloid imaging available for diagnosis. Recent advances in the cryogenic electron microscopy reported distinctly different microstructures for tau fibrils associated with different tauopathies highlighting the possibility to develop tauopathy-specific imaging agents and therapeutics. In addition, it is important to identify the proteins that are associated with disease development and progression to know about their 3D structure to develop various diagnostics, therapeutics and theranostic agents. The current article discusses in detail the disease-associated amyloid and non-amyloid proteins along with their structural insights. We comprehensively discussed various novel proteins associated with NDDs and their implications in disease pathology. In addition, we document various emerging chemical compounds developed for diagnosis and therapy of different NDDs with special emphasis on theranostic agents for better management of NDDs.
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Affiliation(s)
- Kapali Suri
- Department of Computational Biology, Indraprastha Institute of Information Technology (IIIT-Delhi) Okhla, Phase III, New Delhi, 110020, India
| | - Madhu Ramesh
- Bioorganic Chemistry Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O., Bengaluru, 560064, Karnataka, India
| | - Mansi Bhandari
- Department of computer science and engineering, Jamia Hamdard University, Hamdard Nagar, New Delhi, Delhi, 110062
| | - Vishakha Gupta
- Department of Computational Biology, Indraprastha Institute of Information Technology (IIIT-Delhi) Okhla, Phase III, New Delhi, 110020, India
| | - Virendra Kumar
- Department of Computational Biology, Indraprastha Institute of Information Technology (IIIT-Delhi) Okhla, Phase III, New Delhi, 110020, India
| | - Thimmaiah Govindaraju
- Bioorganic Chemistry Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) Jakkur P.O., Bengaluru, 560064, Karnataka, India
| | - N Arul Murugan
- Department of Computational Biology, Indraprastha Institute of Information Technology (IIIT-Delhi) Okhla, Phase III, New Delhi, 110020, India
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3
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Sobek J, Li J, Combes BF, Gerez JA, Henrich MT, Geibl FF, Nilsson PR, Shi K, Rominger A, Oertel WH, Nitsch RM, Nordberg A, Ågren H, Ni R. Efficient characterization of multiple binding sites of small molecule imaging ligands on amyloid-beta, tau and alpha-synuclein. Eur J Nucl Med Mol Imaging 2024:10.1007/s00259-024-06806-7. [PMID: 38953933 DOI: 10.1007/s00259-024-06806-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Accepted: 06/17/2024] [Indexed: 07/04/2024]
Abstract
PURPOSE There is an unmet need for compounds to detect fibrillar forms of alpha-synuclein (αSyn) and 4-repeat tau, which are critical in many neurodegenerative diseases. Here, we aim to develop an efficient surface plasmon resonance (SPR)-based assay to facilitate the characterization of small molecules that can bind these fibrils. METHODS SPR measurements were conducted to characterize the binding properties of fluorescent ligands/compounds toward recombinant amyloid-beta (Aβ)42, K18-tau, full-length 2N4R-tau and αSyn fibrils. In silico modeling was performed to examine the binding pockets of ligands on αSyn fibrils. Immunofluorescence staining of postmortem brain tissue slices from Parkinson's disease patients and mouse models was performed with fluorescence ligands and specific antibodies. RESULTS We optimized the protocol for the immobilization of Aβ42, K18-tau, full-length 2N4R-tau and αSyn fibrils in a controlled aggregation state on SPR-sensor chips and for assessing their binding to ligands. The SPR results from the analysis of binding kinetics suggested the presence of at least two binding sites for all fibrils, including luminescent conjugated oligothiophenes, benzothiazole derivatives, nonfluorescent methylene blue and lansoprazole. In silico modeling studies for αSyn (6H6B) revealed four binding sites with a preference for one site on the surface. Immunofluorescence staining validated the detection of pS129-αSyn positivity in the brains of Parkinson's disease patients and αSyn preformed-fibril injected mice, 6E10-positive Aβ in arcAβ mice, and AT-8/AT-100-positivity in pR5 mice. CONCLUSION SPR measurements of small molecules binding to Aβ42, K18/full-length 2N4R-tau and αSyn fibrils suggested the existence of multiple binding sites. This approach may provide efficient characterization of compounds for neurodegenerative disease-relevant proteinopathies.
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Affiliation(s)
- Jens Sobek
- Functional Genomics Center, University of Zurich & ETH Zurich, Zürich, Switzerland
| | - Junhao Li
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Benjamin F Combes
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, 8952, Zürich, Switzerland
| | - Juan A Gerez
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Zürich, Switzerland
| | - Martin T Henrich
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
- Department of Neurology, Philipps-University Marburg, Marburg, Germany
| | - Fanni F Geibl
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
- Department of Neurology, Philipps-University Marburg, Marburg, Germany
| | - Peter R Nilsson
- Divison of Chemistry, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Kuangyu Shi
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Axel Rominger
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Wolfgang H Oertel
- Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany
- Department of Neurology, Philipps-University Marburg, Marburg, Germany
| | - Roger M Nitsch
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, 8952, Zürich, Switzerland
| | - Agneta Nordberg
- Divison of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Hans Ågren
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Ruiqing Ni
- Institute for Regenerative Medicine, University of Zurich, Wagistrasse 12, 8952, Zürich, Switzerland.
- Department of Nuclear Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
- Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zürich, Switzerland.
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Strobel J, Yousefzadeh-Nowshahr E, Deininger K, Bohn KP, von Arnim CAF, Otto M, Solbach C, Anderl-Straub S, Polivka D, Fissler P, Glatting G, Riepe MW, Higuchi M, Beer AJ, Ludolph A, Winter G. Exploratory Tau PET/CT with [11C]PBB3 in Patients with Suspected Alzheimer's Disease and Frontotemporal Lobar Degeneration: A Pilot Study on Correlation with PET Imaging and Cerebrospinal Fluid Biomarkers. Biomedicines 2024; 12:1460. [PMID: 39062033 PMCID: PMC11274645 DOI: 10.3390/biomedicines12071460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 06/13/2024] [Accepted: 06/25/2024] [Indexed: 07/28/2024] Open
Abstract
Accurately diagnosing Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD) is challenging due to overlapping symptoms and limitations of current imaging methods. This study investigates the use of [11C]PBB3 PET/CT imaging to visualize tau pathology and improve diagnostic accuracy. Given diagnostic challenges with symptoms and conventional imaging, [11C]PBB3 PET/CT's potential to enhance accuracy was investigated by correlating tau pathology with cerebrospinal fluid (CSF) biomarkers, positron emission tomography (PET), computed tomography (CT), amyloid-beta, and Mini-Mental State Examination (MMSE). We conducted [11C]PBB3 PET/CT imaging on 24 patients with suspected AD or FTLD, alongside [11C]PiB PET/CT (13 patients) and [18F]FDG PET/CT (15 patients). Visual and quantitative assessments of [11C]PBB3 uptake using standardized uptake value ratios (SUV-Rs) and correlation analyses with clinical assessments were performed. The scans revealed distinct tau accumulation patterns; 13 patients had no or faint uptake (PBB3-negative) and 11 had moderate to pronounced uptake (PBB3-positive). Significant inverse correlations were found between [11C]PBB3 SUV-Rs and MMSE scores, but not with CSF-tau or CSF-amyloid-beta levels. Here, we show that [11C]PBB3 PET/CT imaging can reveal distinct tau accumulation patterns and correlate these with cognitive impairment in neurodegenerative diseases. Our study demonstrates the potential of [11C]PBB3-PET imaging for visualizing tau pathology and assessing disease severity, offering a promising tool for enhancing diagnostic accuracy in AD and FTLD. Further research is essential to validate these findings and refine the use of tau-specific PET imaging in clinical practice, ultimately improving patient care and treatment outcomes.
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Affiliation(s)
- Joachim Strobel
- Department of Nuclear Medicine, Ulm University Medical Center, 89081 Ulm, Germany
| | | | - Katharina Deininger
- Department of Nuclear Medicine, Ulm University Medical Center, 89081 Ulm, Germany
| | - Karl Peter Bohn
- Department of Nuclear Medicine, Ulm University Medical Center, 89081 Ulm, Germany
| | | | - Markus Otto
- Department of Neurology, Halle University, 06120 Halle, Germany
| | - Christoph Solbach
- Department of Nuclear Medicine, Ulm University Medical Center, 89081 Ulm, Germany
| | | | - Dörte Polivka
- Department of Neurology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Patrick Fissler
- Psychiatric Services Thurgau (Academic Teaching Hospital of the University of Konstanz), 8596 Münsterlingen, Switzerland
| | - Gerhard Glatting
- Department of Nuclear Medicine, Ulm University Medical Center, 89081 Ulm, Germany
| | - Matthias W. Riepe
- Department of Psychiatry and Psychotherapy II, Ulm University, 89075 Ulm, Germany
| | - Makoto Higuchi
- National Institute of Radiological Sciences, Chiba 263-8555, Japan
| | - Ambros J. Beer
- Department of Nuclear Medicine, Ulm University Medical Center, 89081 Ulm, Germany
| | - Albert Ludolph
- Department of Neurology, Ulm University Medical Center, 89081 Ulm, Germany
| | - Gordon Winter
- Department of Nuclear Medicine, Ulm University Medical Center, 89081 Ulm, Germany
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5
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Kumar A, Scarpa M, Nordberg A. Tracing synaptic loss in Alzheimer's brain with SV2A PET-tracer UCB-J. Alzheimers Dement 2024; 20:2589-2605. [PMID: 38363009 PMCID: PMC11032538 DOI: 10.1002/alz.13720] [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: 11/03/2023] [Revised: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 02/17/2024]
Abstract
INTRODUCTION Synaptic loss is an early prominent feature of Alzheimer's disease (AD). The recently developed novel synaptic vesicle 2A protein (SV2A) PET-tracer UCB-J has shown great promise in tracking synaptic loss in AD. However, there have been discrepancies between the findings and a lack of mechanistic insight. METHODS Here we report the first extensive pre-clinical validation studies for UCB-J in control (CN; n = 11) and AD (n = 11) brains using a multidimensional approach of post-mortem brain imaging techniques, radioligand binding, and biochemical studies. RESULTS AND DISCUSSION We demonstrate that UCB-J could target SV2A protein with high specificity and depict synaptic loss at synaptosome levels in AD brain regions compared to CNs. UCB-J showed highest synaptic loss in AD hippocampus followed in descending order by frontal cortex, temporal cortex, parietal cortex, and cerebellum. 3H-UCB-J large brain-section autoradiography and cellular/subcellular fractions binding studies indicated potential off-target interaction with phosphorylated tau (p-tau) species in AD brains, which could have subsequent clinical implications for imaging studies. HIGHLIGHTS Synaptic positron emission tomography (PET)-tracer UCB-J could target synaptic vesicle 2A protein (SV2A) with high specificity in Alzheimer's disease (AD) and control brains. Synaptic PET-tracer UCB-J could depict synaptic loss at synaptosome levels in AD brain regions compared to control. Potential off-target interaction of UCB-J with phosphorylated tau (p-tau) species at cellular/subcellular levels could have subsequent clinical implications for imaging studies, warranting further investigations.
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Affiliation(s)
- Amit Kumar
- Division of Clinical GeriatricsCenter for Alzheimer ResearchDepartment of NeurobiologyCare Sciences and SocietyKarolinska InstitutetStockholmSweden
| | - Miriam Scarpa
- Division of Clinical GeriatricsCenter for Alzheimer ResearchDepartment of NeurobiologyCare Sciences and SocietyKarolinska InstitutetStockholmSweden
| | - Agneta Nordberg
- Division of Clinical GeriatricsCenter for Alzheimer ResearchDepartment of NeurobiologyCare Sciences and SocietyKarolinska InstitutetStockholmSweden
- Theme Inflammation and AgingKarolinska University HospitalStockholmSweden
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6
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Chisholm TS, Hunter CA. A closer look at amyloid ligands, and what they tell us about protein aggregates. Chem Soc Rev 2024; 53:1354-1374. [PMID: 38116736 DOI: 10.1039/d3cs00518f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
The accumulation of amyloid fibrils is characteristic of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease. Detecting these fibrils with fluorescent or radiolabelled ligands is one strategy for diagnosing and better understanding these diseases. A vast number of amyloid-binding ligands have been reported in the literature as a result. To obtain a better understanding of how amyloid ligands bind, we have compiled a database of 3457 experimental dissociation constants for 2076 unique amyloid-binding ligands. These ligands target Aβ, tau, or αSyn fibrils, as well as relevant biological samples including AD brain homogenates. From this database significant variation in the reported dissociation constants of ligands was found, possibly due to differences in the morphology of the fibrils being studied. Ligands were also found to bind to Aβ(1-40) and Aβ(1-42) fibrils with similar affinities, whereas a greater difference was found for binding to Aβ and tau or αSyn fibrils. Next, the binding of ligands to fibrils was shown to be largely limited by the hydrophobic effect. Some Aβ ligands do not fit into this hydrophobicity-limited model, suggesting that polar interactions can play an important role when binding to this target. Finally several binding site models were outlined for amyloid fibrils that describe what ligands target what binding sites. These models provide a foundation for interpreting and designing site-specific binding assays.
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Affiliation(s)
- Timothy S Chisholm
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1 EW, UK.
| | - Christopher A Hunter
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1 EW, UK.
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7
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Kimura T, Sato H, Kano M, Tatsumi L, Tomita T. Novel aspects of the phosphorylation and structure of pathological tau: implications for tauopathy biomarkers. FEBS Open Bio 2024; 14:181-193. [PMID: 37391389 PMCID: PMC10839341 DOI: 10.1002/2211-5463.13667] [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: 04/26/2023] [Revised: 06/17/2023] [Accepted: 06/29/2023] [Indexed: 07/02/2023] Open
Abstract
The deposition of highly phosphorylated and aggregated tau is a characteristic of tauopathies, including Alzheimer's disease. It has long been known that different isoforms of tau are aggregated in different cell types and brain regions in each tauopathy. Recent advances in analytical techniques revealed the details of the biochemical and structural biological differences of tau specific to each tauopathy. In this review, we explain recent advances in the analysis of post-translational modifications of tau, particularly phosphorylation, brought about by the development of mass-spectrometry and Phos-tag technology. We then discuss the structure of tau filaments in each tauopathy revealed by the advent of cryo-EM. Finally, we describe the progress in biofluid and imaging biomarkers for tauopathy. This review summarizes current efforts to elucidate the characteristics of pathological tau and the landscape of the use of tau as a biomarker to diagnose and determine the pathological stage of tauopathy.
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Affiliation(s)
- Taeko Kimura
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical SciencesThe University of TokyoJapan
| | - Haruaki Sato
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical SciencesThe University of TokyoJapan
| | - Maria Kano
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical SciencesThe University of TokyoJapan
| | - Lisa Tatsumi
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical SciencesThe University of TokyoJapan
| | - Taisuke Tomita
- Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical SciencesThe University of TokyoJapan
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8
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Chisholm T, Hunter CA. Ligand Profiling to Characterize Different Polymorphic Forms of α-Synuclein Aggregates. J Am Chem Soc 2023; 145:27030-27037. [PMID: 38029411 PMCID: PMC10722502 DOI: 10.1021/jacs.3c10521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 11/04/2023] [Accepted: 11/06/2023] [Indexed: 12/01/2023]
Abstract
The presence of amyloid fibrils is a characteristic feature of many diseases, most famously neurodegenerative disease. The supramolecular structure of these fibrils appears to be disease-specific. Identifying the unique morphologies of amyloid fibrils could, therefore, form the basis of a diagnostic tool. Here we report a method to characterize the morphology of α-synuclein (αSyn) fibrils based on profiling multiple different ligand binding sites that are present on the surfaces of fibrils. By employing various competition binding assays, seven different types of binding sites were identified on four different morphologies of αSyn fibrils. Similar binding sites on different fibrils were shown to bind ligands with significantly different affinities. We combined this information to construct individual profiles for different αSyn fibrils based on the distribution of binding sites and ligand interactions. These results demonstrate that ligand-based profiling can be used as an analytical method to characterize fibril morphologies with operationally simple fluorescence binding assays.
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Affiliation(s)
- Timothy
S. Chisholm
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
| | - Christopher A. Hunter
- Yusuf Hamied Department of
Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
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9
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Cools R, Kerkhofs K, Leitao RCF, Bormans G. Preclinical Evaluation of Novel PET Probes for Dementia. Semin Nucl Med 2023; 53:599-629. [PMID: 37149435 DOI: 10.1053/j.semnuclmed.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 03/24/2023] [Indexed: 05/08/2023]
Abstract
The development of novel PET imaging agents that selectively bind specific dementia-related targets can contribute significantly to accurate, differential and early diagnosis of dementia causing diseases and support the development of therapeutic agents. Consequently, in recent years there has been a growing body of literature describing the development and evaluation of potential new promising PET tracers for dementia. This review article provides a comprehensive overview of novel dementia PET probes under development, classified by their target, and pinpoints their preclinical evaluation pathway, typically involving in silico, in vitro and ex/in vivo evaluation. Specific target-associated challenges and pitfalls, requiring extensive and well-designed preclinical experimental evaluation assays to enable successful clinical translation and avoid shortcomings observed for previously developed 'well-established' dementia PET tracers are highlighted in this review.
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Affiliation(s)
- Romy Cools
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Kobe Kerkhofs
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium; NURA, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Renan C F Leitao
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Guy Bormans
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
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10
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Gholampour M, Seradj H, Sakhteman A. Structure-Selectivity Relationship Prediction of Tau Imaging Tracers Using Machine Learning-Assisted QSAR Models and Interaction Fingerprint Map. ACS Chem Neurosci 2023. [PMID: 37037183 DOI: 10.1021/acschemneuro.3c00038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023] Open
Abstract
Protein aggregates composed of tau fibrils are major pathologic findings in different tauopathies. An ideal agent for imaging tau fibrils must be highly selective. The molecular basis for the binding of current available compounds to tau aggregates is not well understood. Herein, we provide insights into previously studied positron emission tomography tracers using various computational methods, including machine learning-based quantitative structure-activity relationship (QSAR) classification, docking, and molecular dynamics (MD) simulations to investigate the structural basis of selective tau aggregate binding for potential compounds. The QSAR classification model based on the Random Forest algorithm with an accuracy of 96.6% for the selective and 97.6% for the nonselective class of compounds revealed essential selective moieties. The combination of molecular docking, MD simulations, and molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) binding free-energy calculation showed superior binding energy of ligand 63 toward tau and PHF6, a key hexapeptide in tau aggregation, as the most selective compound in the data set. Dissecting the binding properties of ligand 63 and ligand 8 (the least selective compound) within tau and Aβ structures confirmed that these two compounds favor different binding sites of tau; however, the preferential binding site in Aβ was similar for both with lower binding energies calculated for ligand 8. Results revealed that the number of N-heterocycles, the position of nitrogen atoms, and the presence of tertiary amine are important components of selective binding moieties, and they should be maintained in molecules for selective binding to tau aggregates. The predicted structure-selectivity relationship will facilitate the rational design and further development of selective tau imaging agents.
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Affiliation(s)
- Maryam Gholampour
- Department of Medicinal Chemistry, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz 71468-64685, Iran
| | - Hassan Seradj
- Department of Medicinal Chemistry, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz 71468-64685, Iran
| | - Amirhossein Sakhteman
- Chair of Proteomics and Bioanalytics, Technical University of Munich (TUM), Freising 85354, Germany
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11
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Malarte ML, Gillberg PG, Kumar A, Bogdanovic N, Lemoine L, Nordberg A. Discriminative binding of tau PET tracers PI2620, MK6240 and RO948 in Alzheimer's disease, corticobasal degeneration and progressive supranuclear palsy brains. Mol Psychiatry 2023; 28:1272-1283. [PMID: 36447011 PMCID: PMC10005967 DOI: 10.1038/s41380-022-01875-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 11/03/2022] [Accepted: 11/07/2022] [Indexed: 12/02/2022]
Abstract
Recent mechanistic and structural studies have challenged the classical tauopathy classification approach and revealed the complexity and heterogeneity of tau pathology in Alzheimer's disease (AD) and primary tauopathies such as corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP), progressing beyond distinct tau isoforms. In this multi-tau tracer study, we focused on the new second-generation tau PET tracers PI2620, MK6240 and RO948 to investigate this tau complexity in AD, CBD, and PSP brains using post-mortem radioligand binding studies and autoradiography of large and small frozen brain sections. Saturation binding studies indicated multiple binding sites for 3H-PI2620 in AD, CBD and PSP brains with different binding affinities (Kd ranging from 0.2 to 0.7 nM) and binding site densities (following the order: BmaxAD > BmaxCBD > BmaxPSP). Competitive binding studies complemented these findings, demonstrating the presence of two binding sites [super-high affinity (SHA): IC50(1) = 8.1 pM; and high affinity (HA): IC50(2) = 4.9 nM] in AD brains. Regional binding distribution studies showed that 3H-PI2620 could discriminate between AD (n = 6) and control cases (n = 9), especially in frontal cortex and temporal cortex tissue (p < 0.001) as well as in the hippocampal region (p = 0.02). 3H-PI2620, 3H-MK6240 and 3H-RO948 displayed similar binding behaviour in AD brains (in both homogenate competitive studies and one large frozen hemispherical brain section autoradiography studies) in terms of binding affinities, number of sites and regional patterns. Our small section autoradiography studies in the frontal cortex of CBD (n = 3) and PSP brains (n = 2) showed high specificity for 3H-PI2620 but not for 3H-MK6240 or 3H-RO948. Our findings clearly demonstrate different binding properties among the second-generation tau PET tracers, which may assist in further understanding of tau heterogeneity in AD versus non-AD tauopathies and suggests potential for development of pure selective 4R tau PET tracers.
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Grants
- Stiftelsen för Strategisk Forskning (Swedish Foundation for Strategic Research)
- Stiftelsen Olle Engkvist Byggmästare
- Svenska Forskningsrådet Formas (Swedish Research Council Formas)
- Stockholms Läns Landsting (Stockholm County Council)
- Hjärnfonden (Swedish Brain Foundation)
- Stockholm County Council -Karolinska Institute regional agreement on medical training and clinical research (ALF grant),the Swedish Alzheimer Foundation, the Foundation for Old Servants, Gun and Bertil Stohne’s Foundation, the KI Foundation for Geriatric Diseases, the Swedish Dementia Foundation, the Center for Innovative Medicine (CIMED) Region Stockholm, the Michael J Fox Foundation (MJFF-019728), the Alzheimer Association USA (AARF -21-848395), and the Recherche sur Alzheimer Foundation (Paris, France).
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Affiliation(s)
- Mona-Lisa Malarte
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Per-Göran Gillberg
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Amit Kumar
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Nenad Bogdanovic
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
- Theme Inflammation and Aging, Karolinska University Hospital, Stockholm, Sweden
| | - Laëtitia Lemoine
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Agneta Nordberg
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
- Theme Inflammation and Aging, Karolinska University Hospital, Stockholm, Sweden.
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12
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Varlow C, Vasdev N. Evaluation of Tau Radiotracers in Chronic Traumatic Encephalopathy. J Nucl Med 2023; 64:460-465. [PMID: 36109185 PMCID: PMC10071800 DOI: 10.2967/jnumed.122.264404] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 09/06/2022] [Accepted: 09/06/2022] [Indexed: 11/16/2022] Open
Abstract
Chronic traumatic encephalopathy (CTE) is a neurologic disorder associated with head injuries, diagnosed by the perivascular accumulation of hyperphosphorylated tau protein (phospho-tau) identified at autopsy. Tau PET radiopharmaceuticals developed for imaging Alzheimer disease are under evaluation for brain injuries. The goal of this study was to conduct a head-to-head in vitro evaluation of 5 tau PET radiotracers in subjects pathologically diagnosed with CTE. Methods: Autoradiography was used to assess the specific binding and distribution of 3H-flortaucipir (also known as Tauvid, AV-1451, and T807), 3H-MK-6240 (also known as florquinitau), 3H-PI-2620, 3H-APN-1607 (also known as PM-PBB3 and florzolotau), and 3H-CBD-2115 (also known as 3H-OXD-2115) in fresh-frozen human postmortem CTE brain tissue (stages I-IV). Immunohistochemistry was performed for phospho-tau with AT8, 3R tau with RD3, 4R tau with RD4 and amyloid-β with 6F/3D antibodies. Tau target density (maximum specific binding) was quantified by saturation analysis with 3H-flortaucipir in tissue sections. Results: 3H-flortaucipir demonstrated a positive signal in all CTE cases examined, with varying degrees of specific binding (68.7% ± 10.5%; n = 12) defined by homologous blockade and to a lesser extent by heterologous blockade with MK-6240 (27.3% ± 13.6%; n = 12). The 3H-flortaucipir signal was also displaced by the monoamine oxidase (MAO)-A inhibitor clorgyline (43.9% ± 4.6%; n = 3), indicating off-target binding to MAO-A. 3H-APN-1607 was moderately displaced in homologous blocking studies and was not displaced by 3H-flortaucipir; however, substantial displacement was observed when blocking with the β-amyloid-targeting compound NAV-4694. 3H-MK-6240 and 3H-PI-2620 had negligible binding in all but 2 CTE IV cases, and binding may be attributed to pathology severity or mixed Alzheimer disease/CTE pathology. 3H-CBD-2115 showed moderate binding, displaced under homologous blockade, and aligned with 4R-tau immunostaining. Conclusion: In human CTE tissues, 3H-flortaucipir and 3H-APN-1607 revealed off-target binding to MAO-A and amyloid-β, respectively, and should be considered if these radiotracers are used in PET imaging studies of patients with brain injuries. 3H-MK-6240 and 3H-PI-2620 bind to CTE tau in severe- or mixed-pathology cases, and their respective 18F PET radiotracers warrant further evaluation in patients with severe suspected CTE.
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Affiliation(s)
- Cassis Varlow
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, and Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, and Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
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13
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Hsieh CJ, Giannakoulias S, Petersson EJ, Mach RH. Computational Chemistry for the Identification of Lead Compounds for Radiotracer Development. Pharmaceuticals (Basel) 2023; 16:317. [PMID: 37259459 PMCID: PMC9964981 DOI: 10.3390/ph16020317] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/15/2023] [Accepted: 02/16/2023] [Indexed: 11/19/2023] Open
Abstract
The use of computer-aided drug design (CADD) for the identification of lead compounds in radiotracer development is steadily increasing. Traditional CADD methods, such as structure-based and ligand-based virtual screening and optimization, have been successfully utilized in many drug discovery programs and are highlighted throughout this review. First, we discuss the use of virtual screening for hit identification at the beginning of drug discovery programs. This is followed by an analysis of how the hits derived from virtual screening can be filtered and culled to highly probable candidates to test in in vitro assays. We then illustrate how CADD can be used to optimize the potency of experimentally validated hit compounds from virtual screening for use in positron emission tomography (PET). Finally, we conclude with a survey of the newest techniques in CADD employing machine learning (ML).
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Affiliation(s)
- Chia-Ju Hsieh
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sam Giannakoulias
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - E. James Petersson
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Robert H. Mach
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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14
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Jia J, Zhang Y, Shi Y, Yin X, Wang S, Li Y, Zhao T, Liu W, Zhou A, Jia L. A 19-Year-Old Adolescent with Probable Alzheimer's Disease. J Alzheimers Dis 2023; 91:915-922. [PMID: 36565128 DOI: 10.3233/jad-221065] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Alzheimer's disease (AD) primarily affects older adults. In this report, we present the case of a 19-year-old male with gradual memory decline for 2 years and World Health Organization-University of California Los Angeles Auditory Verbal Learning Test (WHO-UCLA AVLT) results also showing memory impairment. Positron emission tomography-magnetic resonance imaging with 18F fluorodeoxyglucose revealed atrophy of the bilateral hippocampus and hypometabolism in the bilateral temporal lobe. Examination of the patient's cerebrospinal fluid showed an increased concentration of p-tau181 and a decreased amyloid-β 42/40 ratio. However, through whole-genome sequencing, no known gene mutations were identified. Considering the above, the patient was diagnosed with probable AD.
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Affiliation(s)
- Jianping Jia
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China.,Beijing Key Laboratory of Geriatric Cognitive Disorders, Beijing, P.R. China.,Clinical Center for Neurodegenerative Disease and Memory Impairment, Capital Medical University, Beijing, P.R. China.,Center of Alzheimer's Disease, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, P.R. China.,Key Laboratory of Neurodegenerative Diseases, Ministry of Education, Beijing, P.R. China
| | - Yue Zhang
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China
| | - Yuqing Shi
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China
| | - Xuping Yin
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China
| | - Shiyuan Wang
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China
| | - Yan Li
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China
| | - Tan Zhao
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China
| | - Wenying Liu
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China
| | - Aihong Zhou
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China
| | - Longfei Jia
- Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China
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15
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Künze G, Kümpfel R, Rullmann M, Barthel H, Brendel M, Patt M, Sabri O. Molecular Simulations Reveal Distinct Energetic and Kinetic Binding Properties of [ 18F]PI-2620 on Tau Filaments from 3R/4R and 4R Tauopathies. ACS Chem Neurosci 2022; 13:2222-2234. [PMID: 35762647 DOI: 10.1021/acschemneuro.2c00291] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Tauopathies are a class of neurodegenerative disorders characterized by the accumulation of tau protein filaments in the brain. On the basis of isoforms with three or four microtubule-binding repeats (3R or 4R) that constitute tau filaments, tauopathies can be divided into 3R, 4R, and 3R/4R tauopathies. [18F]PI-2620 is a tau-positron emission tomography (PET) tracer that detects tau filaments in the 3R/4R tauopathy Alzheimer's disease (AD) and the 4R tauopathies corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) with differential binding characteristics. A multiscale simulation workflow, including molecular docking, molecular dynamics simulation, metadynamics, and Brownian dynamics, was applied to uncover the molecular basis for the different binding properties of [18F]PI-2620 in these tauopathies. The energetically best binding sites of [18F]PI-2620 in the AD-tau filament are located in the C-shaped groove of the filament core structure that is accessible to the outside. The most favorable binding sites in CBD-tau and PSP-tau filaments are localized to cavities in the inner filament core. Sites on the outer surface have higher binding free energies, and interaction of [18F]PI-2620 at these sites was short-lived in the molecular dynamics simulations. Computationally predicted associated rates of [18F]PI-2620 with the groove sites in the AD-tau filament were higher than association rates with the cavity sites in the CBD- and PSP-tau filaments. The results indicate that tau filaments in AD combine favorable energetic and kinetic properties with regard to tracer binding, while the binding of [18F]PI-2620 to filaments in CBD and PSP is kinetically restricted. Our findings reveal that distinct structural, energetic, and kinetic properties of tau filaments from AD, CBD, and PSP govern their interaction with PET tracers, which highlights the possibility to achieve tau isoform specificity in future tracer developments.
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Affiliation(s)
- Georg Künze
- Institute for Drug Discovery, University of Leipzig, 04103 Leipzig, Germany
| | - Richy Kümpfel
- Institute for Drug Discovery, University of Leipzig, 04103 Leipzig, Germany
| | - Michael Rullmann
- Department of Nuclear Medicine, University of Leipzig, Leipzig 04103, Germany
| | - Henryk Barthel
- Department of Nuclear Medicine, University of Leipzig, Leipzig 04103, Germany
| | - Matthias Brendel
- Department of Nuclear Medicine, University Hospital of Munich, LMU Munich, 81377 Munich, Germany.,German Center for Neurodegenerative Diseases (DZNE), Munich 81377, Germany.,Munich Cluster for Systems Neurology (SyNergy), Munich 81377, Germany
| | - Marianne Patt
- Department of Nuclear Medicine, University of Leipzig, Leipzig 04103, Germany
| | - Osama Sabri
- Department of Nuclear Medicine, University of Leipzig, Leipzig 04103, Germany
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16
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Landrieu I, Dupré E, Sinnaeve D, El Hajjar L, Smet-Nocca C. Deciphering the Structure and Formation of Amyloids in Neurodegenerative Diseases With Chemical Biology Tools. Front Chem 2022; 10:886382. [PMID: 35646824 PMCID: PMC9133342 DOI: 10.3389/fchem.2022.886382] [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: 02/28/2022] [Accepted: 04/20/2022] [Indexed: 11/24/2022] Open
Abstract
Protein aggregation into highly ordered, regularly repeated cross-β sheet structures called amyloid fibrils is closely associated to human disorders such as neurodegenerative diseases including Alzheimer's and Parkinson's diseases, or systemic diseases like type II diabetes. Yet, in some cases, such as the HET-s prion, amyloids have biological functions. High-resolution structures of amyloids fibrils from cryo-electron microscopy have very recently highlighted their ultrastructural organization and polymorphisms. However, the molecular mechanisms and the role of co-factors (posttranslational modifications, non-proteinaceous components and other proteins) acting on the fibril formation are still poorly understood. Whether amyloid fibrils play a toxic or protective role in the pathogenesis of neurodegenerative diseases remains to be elucidated. Furthermore, such aberrant protein-protein interactions challenge the search of small-molecule drugs or immunotherapy approaches targeting amyloid formation. In this review, we describe how chemical biology tools contribute to new insights on the mode of action of amyloidogenic proteins and peptides, defining their structural signature and aggregation pathways by capturing their molecular details and conformational heterogeneity. Challenging the imagination of scientists, this constantly expanding field provides crucial tools to unravel mechanistic detail of amyloid formation such as semisynthetic proteins and small-molecule sensors of conformational changes and/or aggregation. Protein engineering methods and bioorthogonal chemistry for the introduction of protein chemical modifications are additional fruitful strategies to tackle the challenge of understanding amyloid formation.
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Affiliation(s)
- Isabelle Landrieu
- University Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1167 - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, Lille, France
- CNRS EMR9002 Integrative Structural Biology, Lille, France
| | - Elian Dupré
- University Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1167 - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, Lille, France
- CNRS EMR9002 Integrative Structural Biology, Lille, France
| | - Davy Sinnaeve
- University Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1167 - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, Lille, France
- CNRS EMR9002 Integrative Structural Biology, Lille, France
| | - Léa El Hajjar
- University Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1167 - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, Lille, France
- CNRS EMR9002 Integrative Structural Biology, Lille, France
| | - Caroline Smet-Nocca
- University Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1167 - RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, Lille, France
- CNRS EMR9002 Integrative Structural Biology, Lille, France
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17
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Maschio C, Ni R. Amyloid and Tau Positron Emission Tomography Imaging in Alzheimer’s Disease and Other Tauopathies. Front Aging Neurosci 2022; 14:838034. [PMID: 35527737 PMCID: PMC9074832 DOI: 10.3389/fnagi.2022.838034] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 03/24/2022] [Indexed: 12/11/2022] Open
Abstract
The detection and staging of Alzheimer’s disease (AD) using non-invasive imaging biomarkers is of substantial clinical importance. Positron emission tomography (PET) provides readouts to uncover molecular alterations in the brains of AD patients with high sensitivity and specificity. A variety of amyloid-β (Aβ) and tau PET tracers are already available for the clinical diagnosis of AD, but there is still a lack of imaging biomarkers with high affinity and selectivity for tau inclusions in primary tauopathies, such as progressive supranuclear palsy (PSP), corticobasal degeneration (CBD) and Pick’s disease (PiD). This review aims to provide an overview of the existing Aβ and tau PET imaging biomarkers and their binding properties from in silico, in vitro, and in vivo assessment. Imaging biomarkers for pathologic proteins are vital for clinical diagnosis, disease staging and monitoring of the potential therapeutic approaches of AD. Off-target binding of radiolabeled tracers to white matter or other neural structures is one confounding factor when interpreting images. To improve binding properties such as binding affinity and to eliminate off-target binding, second generation of tau PET tracers have been developed. To conclude, we further provide an outlook for imaging tauopathies and other pathological features of AD and primary tauopathies.
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Affiliation(s)
- Cinzia Maschio
- Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
- *Correspondence: Cinzia Maschio,
| | - Ruiqing Ni
- Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering, ETH Zürich and University of Zurich, Zurich, Switzerland
- Ruiqing Ni,
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18
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Non-invasive imaging of tau-targeted probe uptake by whole brain multi-spectral optoacoustic tomography. Eur J Nucl Med Mol Imaging 2022; 49:2137-2152. [PMID: 35128565 PMCID: PMC9165274 DOI: 10.1007/s00259-022-05708-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 01/25/2022] [Indexed: 02/06/2023]
Abstract
Purpose Abnormal tau accumulation within the brain plays an important role in tauopathies such as Alzheimer’s disease and frontotemporal dementia. High-resolution imaging of tau deposits at the whole-brain scale in animal disease models is highly desired. Methods We approached this challenge by non-invasively imaging the brains of P301L mice of 4-repeat tau with concurrent volumetric multi-spectral optoacoustic tomography (vMSOT) at ~ 115 μm spatial resolution using the tau-targeted pyridinyl-butadienyl-benzothiazole derivative PBB5 (i.v.). In vitro probe characterization, concurrent vMSOT and epi-fluorescence imaging of in vivo PBB5 targeting (i.v.) was performed in P301L and wild-type mice, followed by ex vivo validation using AT-8 antibody for phosphorylated tau. Results PBB5 showed specific binding to recombinant K18 tau fibrils by fluorescence assay, to post-mortem Alzheimer’s disease brain tissue homogenate by competitive binding against [11C]PBB3 and to tau deposits (AT-8 positive) in post-mortem corticobasal degeneration and progressive supranuclear palsy brains. Dose-dependent optoacoustic and fluorescence signal intensities were observed in the mouse brains following i.v. administration of different concentrations of PBB5. In vivo vMSOT brain imaging of P301L mice showed higher retention of PBB5 in the tau-laden cortex and hippocampus compared to wild-type mice, as confirmed by ex vivo vMSOT, epi-fluorescence, multiphoton microscopy, and immunofluorescence staining. Conclusions We demonstrated non-invasive whole-brain imaging of tau in P301L mice with vMSOT system using PBB5 at a previously unachieved ~ 115 μm spatial resolution. This platform provides a new tool to study tau spreading and clearance in a tauopathy mouse model, foreseeable in monitoring tau targeting putative therapeutics. Supplementary Information The online version contains supplementary material available at 10.1007/s00259-022-05708-w.
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19
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Ni R, Nitsch RM. Recent Developments in Positron Emission Tomography Tracers for Proteinopathies Imaging in Dementia. Front Aging Neurosci 2022; 13:751897. [PMID: 35046791 PMCID: PMC8761855 DOI: 10.3389/fnagi.2021.751897] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/17/2021] [Indexed: 12/15/2022] Open
Abstract
An early detection and intervention for dementia represent tremendous unmet clinical needs and priorities in society. A shared feature of neurodegenerative diseases causing dementia is the abnormal accumulation and spreading of pathological protein aggregates, which affect the selective vulnerable circuit in a disease-specific pattern. The advancement in positron emission tomography (PET) biomarkers has accelerated the understanding of the disease mechanism and development of therapeutics for Alzheimer's disease and Parkinson's disease. The clinical utility of amyloid-β PET and the clinical validity of tau PET as diagnostic biomarker for Alzheimer's disease continuum have been demonstrated. The inclusion of biomarkers in the diagnostic criteria has introduced a paradigm shift that facilitated the early and differential disease diagnosis and impacted on the clinical management. Application of disease-modifying therapy likely requires screening of patients with molecular evidence of pathological accumulation and monitoring of treatment effect assisted with biomarkers. There is currently still a gap in specific 4-repeat tau imaging probes for 4-repeat tauopathies and α-synuclein imaging probes for Parkinson's disease and dementia with Lewy body. In this review, we focused on recent development in molecular imaging biomarkers for assisting the early diagnosis of proteinopathies (i.e., amyloid-β, tau, and α-synuclein) in dementia and discussed future perspectives.
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Affiliation(s)
- Ruiqing Ni
- Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering, ETH & University of Zurich, Zurich, Switzerland
| | - Roger M. Nitsch
- Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
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20
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Mena AM, Strafella AP. Imaging pathological tau in atypical parkinsonisms: A review. Clin Park Relat Disord 2022; 7:100155. [PMID: 35880206 PMCID: PMC9307942 DOI: 10.1016/j.prdoa.2022.100155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/06/2022] [Accepted: 07/07/2022] [Indexed: 11/27/2022] Open
Abstract
[18F]AV-1451 displays mixed results for specificity to 4R CBD- and PSP-tau. [18F]PI-2620 and [18F]PM-PBB3 are the most promising second-generation tau PET tracers. Research using second-generation tau PET tracers in CBD and PSP is still limited. Finding an imaging diagnostic biomarker requires further work with larger samples.
Atypical parkinsonisms (APs) are a group of diseases linked to tau pathology. These include progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). In the initial stages, these APs may have similar clinical manifestations to Parkinson’s disease (PD) and other parkinsonisms: bradykinesia, postural instability, tremor, and cognitive decline. Because of this, one major hurdle is the accurate early diagnosis of APs. Recent advances in positron emission tomography (PET) radiotracer development have allowed for targeting pathological tau in Alzheimer’s disease (AD). Currently, work is still in progress for identifying a first-in-class radiotracer for imaging tau in APs. In this review, we evaluate the literature on in vitro and in vivo testing of current tau PET radiotracers in APs. The tau PET tracers assessed include both first-generation tracers ([18F]AV-1451, [18F]FDDNP, [18F]THK derivatives, and [11C]PBB3) and second-generation tracers ([18F]PM-PBB3, [18F]PI-2620, [18F]RO-948, [18F]JNJ-067, [18F]MK-6240, and [18F]CBD-2115). Concerns regarding off-target binding to cerebral white matter and the basal ganglia are still prominent with first-generation tracers, but this seems to have been mediated in a handful of second-generation tracers, including [18F]PI-2620 and [18F]PM-PBB3. Additionally, these two tracers and [18F]MK-6240 show promising results for imaging PSP- and CBD-tau. Overall, [18F]AV-1451 is the most widely studied tracer but the mixed results regarding its efficacy for use in imaging AP-tau is a cause for concern moving forward. Instead, future work may benefit from focusing on the second-generation radiotracers which seem to have a higher specificity for AP-tau than those originally developed for imaging AD-tau.
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21
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NRM 2021 Abstract Booklet. J Cereb Blood Flow Metab 2021; 41:11-309. [PMID: 34905986 PMCID: PMC8851538 DOI: 10.1177/0271678x211061050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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22
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Ramesh M, Acharya A, Murugan NA, Ila H, Govindaraju T. Thiophene-Based Dual Modulators of Aβ and Tau Aggregation. Chembiochem 2021; 22:3348-3357. [PMID: 34546619 DOI: 10.1002/cbic.202100383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/21/2021] [Indexed: 01/29/2023]
Abstract
Alzheimer's disease is characterized by the accumulation of amyloid beta (Aβ) and Tau aggregates in the brain, which induces various pathological events resulting in neurodegeneration. There have been continuous efforts to develop modulators of the Aβ and Tau aggregation process to halt or modify disease progression. A few small-molecule-based inhibitors that target both Aβ and Tau pathology have been reported. Here, we report the screening of a targeted library of small molecules to modulate Aβ and Tau aggregation together with their in vitro, in silico and cellular studies. In vitro ThT fluorescence assay, dot blot assay, gel electrophoresis and transmission electron microscopy (TEM) results have shown that thiophene-based lead molecules effectively modulate Aβ aggregation and inhibit Tau aggregation. In silico studies performed by employing molecular docking, molecular dynamics and binding-free energy calculations have helped in understanding the mechanism of interaction of the lead thiophene compounds with Aβ and Tau fibril targets. In cellulo studies revealed that the lead candidate is biocompatible and effectively ameliorates neuronal cells from Aβ and Tau-mediated amyloid toxicity.
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Affiliation(s)
- Madhu Ramesh
- Bioorganic Chemistry Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bengaluru, 560064, Karnataka, India
| | - Anand Acharya
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bengaluru, 560064, Karnataka, India
| | - N Arul Murugan
- Department of Computer Science, School of Electrical Engineering and Computer Science, KTH Royal Institute of Technology, 10044, Stockholm, Sweden
| | - Hiriyakkanavar Ila
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bengaluru, 560064, Karnataka, India
| | - Thimmaiah Govindaraju
- Bioorganic Chemistry Laboratory, New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bengaluru, 560064, Karnataka, India
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