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Malyshka D, Jimenez-Harrison D, Kuret J. Sedimentation and Laser Light Scattering Methods for Quantifying Synthetic Tau Aggregation Propensity. Methods Mol Biol 2024; 2754:117-129. [PMID: 38512664 DOI: 10.1007/978-1-0716-3629-9_7] [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] [Indexed: 03/23/2024]
Abstract
Tau aggregation assays detect and quantify the conversion of soluble tau monomers into species having filamentous or oligomeric structure. Assays for filamentous aggregates in cross-β-sheet conformation leverage optical, biochemical, or biophysical methods, each with their own advantages and throughput capacity. Here we provide protocols for two medium-throughput assays based on sedimentation and laser light scattering and compare their performance, their utility for characterizing tau aggregation dynamics, and their limitations relative to other approaches. Additionally, a protocol for transmission electron microscopy analysis is updated so as to be compatible with the truncated tau variants that have emerged as powerful tools for interrogating the structural basis of tau polymorphism. Together these methods contribute to a rich tool kit for interrogating tau aggregation kinetics and propensity over a wide range of experimental conditions.
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Affiliation(s)
- Dmitry Malyshka
- Medical Scientist Training Program, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Daniela Jimenez-Harrison
- Medical Scientist Training Program, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Jeff Kuret
- Department of Biological Chemistry and Pharmacology, The Ohio State University College of Medicine, Columbus, OH, USA.
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2
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Ingham DJ, Hillyer KM, McGuire MJ, Gamblin TC. In vitro Tau Aggregation Inducer Molecules Influence the Effects of MAPT Mutations on Aggregation Dynamics. Biochemistry 2022; 61:1243-1259. [PMID: 35731895 PMCID: PMC9260964 DOI: 10.1021/acs.biochem.2c00111] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 06/01/2022] [Indexed: 11/28/2022]
Abstract
Alzheimer's disease (AD) and Alzheimer's disease-related dementias (ADRDs) affect 6 million Americans, and they are projected to have an estimated health care cost of $355 billion for 2021. A histopathological hallmark of AD and many ADRDs is the aberrant intracellular accumulation of the microtubule-associated protein tau. These neurodegenerative disorders that contain tau aggregates are collectively known as tauopathies, and recent structural studies have shown that different tauopathies are characterized by different "strains" of tau filaments. In addition, mutations in the gene that encodes for tau protein expression have been associated with a group of tauopathies known as frontotemporal dementias with parkinsonism linked to chromosome 17 (FTDP-17 or familial frontotemporal dementia). In vitro studies often use small molecules to induce tau aggregation as tau is extremely soluble and does not spontaneously aggregate under typical laboratory conditions, and the use of authentic filaments to conduct in vitro studies is not feasible. This study highlights how different inducer molecules can have fundamental disparities to how disease-related mutations affect the aggregation dynamics of tau. Using three different classes of tau aggregation inducer molecules, we characterized disease-relevant mutations in tau's PGGG motifs at positions P301S, P332S, and P364S. When comparing these mutations to wild-type tau, we found that depending on the type of inducer molecule used, we saw fundamental differences in total aggregation, aggregation kinetics, immunoreactivity, and filament numbers, length, and width. These data are consistent with the possibility that different tau aggregation inducer molecules make different structural polymorphs, although this possibility would need to be confirmed by high-resolution techniques such as cryo-electron microscopy. The data also show that disease-associated missense mutations in tau impact tau aggregation differently depending on the mechanism of aggregation induction.
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Affiliation(s)
- David J. Ingham
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Kelsey M. Hillyer
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Madison J. McGuire
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, 66045, United States
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3
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Mukherjee S, Panda D. Contrasting Effects of Ferric and Ferrous Ions on Oligomerization and Droplet Formation of Tau: Implications in Tauopathies and Neurodegeneration. ACS Chem Neurosci 2021; 12:4393-4405. [PMID: 34783530 DOI: 10.1021/acschemneuro.1c00377] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The dysregulation of metal homeostasis is reported to enhance the aggregation of tau, a key neuronal microtubule-associated protein. Herein, we found that ferric (Fe3+) ions enhanced tau aggregation. Fe3+ and Al3+ induced tau aggregation while several trivalent metal ions such as Cr3+, La3+, and V3+ had no discernable effect on tau aggregation. Fe3+ reduced the critical concentration of tau required for the liquid-liquid phase separation (LLPS); however, Cr3+, La3+, and V3+ did not affect tau droplet formation. Dynamic light scattering, atomic force microscopic, and transmission electron microscopic analysis suggested that Fe3+ significantly increased the formation of tau oligomers and fibrils. In contrast, Fe2+ neither enhanced tau droplet formation nor increased the heparin-induced aggregation of tau. Using a tryptophan mutant (Y310W-tau) of tau, Fe3+ was found to bind to tau with four times higher affinity than Fe2+. Acrylamide quenching of the tryptophan fluorescence of Y310W-tau, 1-anilino-8-naphthalene sulfonate (ANS) fluorescence experiment, and far-UV circular dichroism analysis indicated that Fe3+ decreased the solvent exposure of the tryptophan residue, perturbed the hydrophobic surface arrangement, and disrupted the secondary structure of tau, respectively. The increase in the β-sheet content and a subsequent decrease in the disordered content of tau due to the binding of Fe3+ may favor tau aggregation. Fe3+ may enhance and stabilize the non-covalent interactions between disordered domains of tau molecules leading to tau aggregation. The data highlighted the relationship between the dysregulation of ferric ions and neurodegenerative disorders.
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Affiliation(s)
- Sandipan Mukherjee
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Dulal Panda
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
- National Institute of Pharmaceutical Education and Research, S.A.S. Nagar, Punjab 160062, India
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4
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Vignon A, Salvador-Prince L, Lehmann S, Perrier V, Torrent J. Deconstructing Alzheimer's Disease: How to Bridge the Gap between Experimental Models and the Human Pathology? Int J Mol Sci 2021; 22:8769. [PMID: 34445475 PMCID: PMC8395727 DOI: 10.3390/ijms22168769] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/05/2021] [Accepted: 08/06/2021] [Indexed: 02/07/2023] Open
Abstract
Discovered more than a century ago, Alzheimer's disease (AD) is not only still present in our societies but has also become the most common dementia, with 50 million people worldwide affected by the disease. This number is expected to double in the next generation, and no cure is currently available to slow down or stop the disease progression. Recently, some advances were made due to the approval of the aducanumab treatment by the American Food and Drug Administration. The etiology of this human-specific disease remains poorly understood, and the mechanisms of its development have not been completely clarified. Several hypotheses concerning the molecular mechanisms of AD have been proposed, but the existing studies focus primarily on the two main markers of the disease: the amyloid β peptides, whose aggregation in the brain generates amyloid plaques, and the abnormally phosphorylated tau proteins, which are responsible for neurofibrillary tangles. These protein aggregates induce neuroinflammation and neurodegeneration, which, in turn, lead to cognitive and behavioral deficits. The challenge is, therefore, to create models that best reproduce this pathology. This review aims at gathering the different existing AD models developed in vitro, in cellulo, and in vivo. Many models have already been set up, but it is necessary to identify the most relevant ones for our investigations. The purpose of the review is to help researchers to identify the most pertinent disease models, from the most often used to the most recently generated and from simple to complex, explaining their specificities and giving concrete examples.
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Affiliation(s)
- Anaïs Vignon
- INM, University of Montpellier, INSERM, 34095 Montpellier, France; (A.V.); (L.S.-P.)
| | - Lucie Salvador-Prince
- INM, University of Montpellier, INSERM, 34095 Montpellier, France; (A.V.); (L.S.-P.)
| | - Sylvain Lehmann
- INM, University of Montpellier, INSERM, CHU Montpellier, 34095 Montpellier, France;
| | - Véronique Perrier
- INM, University of Montpellier, INSERM, CNRS, 34095 Montpellier, France
| | - Joan Torrent
- INM, University of Montpellier, INSERM, 34095 Montpellier, France; (A.V.); (L.S.-P.)
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Ingham DJ, Blankenfeld BR, Chacko S, Perera C, Oakley BR, Gamblin TC. Fungally Derived Isoquinoline Demonstrates Inducer-Specific Tau Aggregation Inhibition. Biochemistry 2021; 60:1658-1669. [PMID: 34009955 PMCID: PMC8173610 DOI: 10.1021/acs.biochem.1c00111] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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The microtubule-associated
protein tau promotes the stabilization
of the axonal cytoskeleton in neurons. In several neurodegenerative
diseases, such as Alzheimer’s disease, tau has been found to
dissociate from microtubules, leading to the formation of pathological
aggregates that display an amyloid fibril-like structure. Recent structural
studies have shown that the tau filaments isolated from different
neurodegenerative disorders have structurally distinct fibril cores
that are specific to the disease. These “strains” of
tau fibrils appear to propagate between neurons in a prion-like fashion
that maintains their initial template structure. In addition, the
strains isolated from diseased tissue appear to have structures that
are different from those made by the most commonly used in
vitro modeling inducer molecule, heparin. The structural
differences among strains in different diseases and in vitro-induced tau fibrils may contribute to recent failures in clinical
trials of compounds designed to target tau pathology. This study identifies
an isoquinoline compound (ANTC-15) isolated from the fungus Aspergillus nidulans that can both inhibit filaments induced
by arachidonic acid (ARA) and disassemble preformed ARA fibrils. When
compared to a tau aggregation inhibitor currently in clinical trials
(LMTX, LMTM, or TRx0237), ANTC-15 and LMTX were found to have opposing
inducer-specific activities against ARA and heparin in vitro-induced tau filaments. These findings may help explain the disappointing
results in translating potent preclinical inhibitor candidates to
successful clinical treatments.
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Affiliation(s)
- David J Ingham
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, United States
| | - Bryce R Blankenfeld
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, United States
| | - Shibin Chacko
- Synthetic Chemical Biology Core Facility, University of Kansas, Lawrence, Kansas 66047, United States
| | - Chamani Perera
- Synthetic Chemical Biology Core Facility, University of Kansas, Lawrence, Kansas 66047, United States
| | - Berl R Oakley
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, United States
| | - Truman Christopher Gamblin
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, United States.,Department of Biology, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
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Montalbano M, McAllen S, Cascio FL, Sengupta U, Garcia S, Bhatt N, Ellsworth A, Heidelman EA, Johnson OD, Doskocil S, Kayed R. TDP-43 and Tau Oligomers in Alzheimer's Disease, Amyotrophic Lateral Sclerosis, and Frontotemporal Dementia. Neurobiol Dis 2020; 146:105130. [PMID: 33065281 PMCID: PMC7703712 DOI: 10.1016/j.nbd.2020.105130] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 09/25/2020] [Accepted: 10/06/2020] [Indexed: 12/22/2022] Open
Abstract
Proteinaceous aggregates are major hallmarks of several neurodegenerative diseases. Aggregates of post-translationally modified transactive response (TAR)-DNA binding protein 43 (TDP-43) in cytoplasmic inclusion bodies are characteristic features in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Recent studies have also reported TDP-43 aggregation in Alzheimer's disease (AD). TDP-43 is an RNA/DNA binding protein (RBP) mainly present in the nucleus. In addition to several RBPs, TDP-43 has also been reported in stress granules in FTD and ALS pathologies. Despite knowledge of cytoplasmic mislocalization of TDP-43, the cellular effects of TDP-43 aggregates and their cytotoxic mechanism(s) remain to be clarified. We hypothesize that TDP-43 forms oligomeric assemblies that associate with tau, another key protein involved in ALS and FTD. However, no prior studies have investigated the interactions between TDP-43 oligomers and tau. It is therefore important to thoroughly investigate the cross-seeding properties and cellular localization of both TDP-43 and tau oligomers in neurodegenerative diseases. Here, we demonstrate the effect of tau on the cellular localization of TDP-43 in WT and P301L tau-inducible cell models (iHEK) and in WT HEK-293 cells treated exogenously with soluble human recombinant tau oligomers (Exo-rTauO). We observed cytoplasmic TDP-43 accumulation o in the presence of tau in these cell models. We also studied the occurrence of TDP-43 oligomers in AD, ALS, and FTD human brain tissue using novel antibodies generated against TDP-43 oligomers as well as generic TDP-43 antibodies. Finally, we examined the cross-seeding property of AD, ALS, and FTD brain-derived TDP-43 oligomers (BDT43Os) on tau aggregation using biochemical and biophysical assays. Our results allow us to speculate that TDP-43/tau interactions might play a role in AD, ALS, and FTD.
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Affiliation(s)
- Mauro Montalbano
- Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Departments of Neurology, Neuroscience, and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Salome McAllen
- Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Departments of Neurology, Neuroscience, and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Filippa Lo Cascio
- Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Departments of Neurology, Neuroscience, and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Urmi Sengupta
- Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Departments of Neurology, Neuroscience, and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Stephanie Garcia
- Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Departments of Neurology, Neuroscience, and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Nemil Bhatt
- Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Departments of Neurology, Neuroscience, and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Anna Ellsworth
- Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Departments of Neurology, Neuroscience, and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Eric A Heidelman
- School of Medicine, University of Texas Medical Branch, UTMB, Galveston, TX 77555, USA
| | - Omar D Johnson
- School of Medicine, University of Texas Medical Branch, UTMB, Galveston, TX 77555, USA
| | - Samantha Doskocil
- Neuroscience Summer Undergraduate Research Program, NSURP Program 2018, University of Texas Medical Branch, UTMB, Galveston, TX 77555, USA
| | - Rakez Kayed
- Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA; Departments of Neurology, Neuroscience, and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.
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7
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Barracchia CG, Tira R, Parolini F, Munari F, Bubacco L, Spyroulias GA, D’Onofrio M, Assfalg M. Unsaturated Fatty Acid-Induced Conformational Transitions and Aggregation of the Repeat Domain of Tau. Molecules 2020; 25:molecules25112716. [PMID: 32545360 PMCID: PMC7321374 DOI: 10.3390/molecules25112716] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 06/07/2020] [Accepted: 06/10/2020] [Indexed: 12/20/2022] Open
Abstract
Background: The intrinsically disordered, amyloidogenic protein Tau associates with diverse classes of molecules, including proteins, nucleic acids, and lipids. Mounting evidence suggests that fatty acid molecules could play a role in the dysfunction of this protein, however, their interaction with Tau remains poorly characterized. Methods: In a bid to elucidate the association of Tau with unsaturated fatty acids at the sub-molecular level, we carried out a variety of solution NMR experiments in combination with circular dichroism and fluorescence measurements. Our study shows that Tau4RD, the highly basic four-repeat domain of Tau, associates strongly with arachidonic and oleic acid assemblies in a high lipid/protein ratio, perturbing their supramolecular states and itself undergoing time-dependent structural adaptation. The structural signatures of Tau4RD/fatty acid aggregates appear similar for arachidonic acid and oleic acid, however, they are distinct from those of another prototypical intrinsically disordered protein, α-synuclein, when bound to these lipids, revealing protein-specific conformational adaptations. Both fatty acid molecules are found to invariably promote the self-aggregation of Tau4RD and of α-synuclein. Conclusions: This study describes the reciprocal influence that Tau4RD and fatty acids exert on their conformational states, contributing to our understanding of fundamental aspects of Tau/lipid co-assembly.
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Affiliation(s)
- Carlo Giorgio Barracchia
- Department of Biotechnology, University of Verona, 37134 Verona, Italy; (C.G.B.); (R.T.); (F.P.); (F.M.); (M.D.)
| | - Roberto Tira
- Department of Biotechnology, University of Verona, 37134 Verona, Italy; (C.G.B.); (R.T.); (F.P.); (F.M.); (M.D.)
| | - Francesca Parolini
- Department of Biotechnology, University of Verona, 37134 Verona, Italy; (C.G.B.); (R.T.); (F.P.); (F.M.); (M.D.)
| | - Francesca Munari
- Department of Biotechnology, University of Verona, 37134 Verona, Italy; (C.G.B.); (R.T.); (F.P.); (F.M.); (M.D.)
| | - Luigi Bubacco
- Department of Biology, University of Padova, 35131 Padova, Italy;
| | | | - Mariapina D’Onofrio
- Department of Biotechnology, University of Verona, 37134 Verona, Italy; (C.G.B.); (R.T.); (F.P.); (F.M.); (M.D.)
| | - Michael Assfalg
- Department of Biotechnology, University of Verona, 37134 Verona, Italy; (C.G.B.); (R.T.); (F.P.); (F.M.); (M.D.)
- Correspondence:
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Vasili E, Dominguez-Meijide A, Outeiro TF. Spreading of α-Synuclein and Tau: A Systematic Comparison of the Mechanisms Involved. Front Mol Neurosci 2019; 12:107. [PMID: 31105524 PMCID: PMC6494944 DOI: 10.3389/fnmol.2019.00107] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 04/09/2019] [Indexed: 01/01/2023] Open
Abstract
Alzheimer's disease (AD) and Parkinson's disease (PD) are age-associated neurodegenerative disorders characterized by the misfolding and aggregation of alpha-synuclein (aSyn) and tau, respectively. The coexistence of aSyn and tau aggregates suggests a strong overlap between tauopathies and synucleinopathies. Interestingly, misfolded forms of aSyn and tau can propagate from cell to cell, and throughout the brain, thereby templating the misfolding of native forms of the proteins. The exact mechanisms involved in the propagation of the two proteins show similarities, and are reminiscent of the spreading characteristic of prion diseases. Recently, several models were developed to study the spreading of aSyn and tau. Here, we discuss the mechanisms involved, the similarities and differences between the spreading of the two proteins and that of the prion protein, and the different cell and animal models used for studying these processes. Ultimately, a deeper understanding of the molecular mechanisms involved may lead to the identification of novel targets for therapeutic intervention in a variety of devastating neurodegenerative diseases.
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Affiliation(s)
- Eftychia Vasili
- Department of Experimental Neurodegeneration, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany
| | - Antonio Dominguez-Meijide
- Department of Experimental Neurodegeneration, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany
| | - Tiago Fleming Outeiro
- Department of Experimental Neurodegeneration, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany.,Max Planck Institute for Experimental Medicine, Goettingen, Germany.,The Medical School, Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne, United Kingdom
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9
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Mutreja Y, Combs B, Gamblin TC. FTDP-17 Mutations Alter the Aggregation and Microtubule Stabilization Propensity of Tau in an Isoform-Specific Fashion. Biochemistry 2018; 58:742-754. [PMID: 30562452 DOI: 10.1021/acs.biochem.8b01039] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
More than 50 different intronic and exonic autosomal dominant mutations in the tau gene have been linked to the neurodegenerative disorder frontotemporal dementia with Parkinsonism linked to chromosome-17 (FTDP-17). Although the pathological and clinical presentation of this disorder is heterogeneous among patients, the deposition of tau as pathological aggregates is a common feature. Collectively, FTDP-17 mutations have been shown to alter tau's ability to stabilize microtubules, enhance its aggregation, alter mRNA splicing, or induce its hyperphosphorylation, among other effects. Previous in vitro studies from our lab revealed that these mutations differ markedly from each other in the longest 2N4R isoform of tau. However, it is not entirely known whether the effect of a single mutation varies when compared between different isoforms of tau. Differences in the isoelectric points of the N-terminal region of tau isoforms lead to changes in their biochemical properties, raising the possibility that isoforms could also be disproportionately affected by disease-related mechanisms such as mutations. We therefore performed a comparative study of three FTDP-17 mutations present in different regions of tau (R5L, P301L, and R406W) in the three 4R isoforms of tau. We observed significant differences in the effect these mutations exert on the total amount and kinetics of aggregation, aggregate length distributions, and microtubule stabilizing propensity of 4R tau isoforms for all three selected mutants. These results demonstrate that different combinations of FTDP-17 mutations and tau isoforms are functionally distinct and could have important implications for our understanding of disease and animal models of tauopathies.
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Affiliation(s)
- Yamini Mutreja
- Department of Molecular Biosciences , University of Kansas , 1200 Sunnyside Ave , Lawrence , Kansas 66045 , United States
| | - Benjamin Combs
- Department of Molecular Biosciences , University of Kansas , 1200 Sunnyside Ave , Lawrence , Kansas 66045 , United States.,Department of Translational Science & Molecular Medicine, College of Human Medicine , Michigan State University , Grand Rapids , Michigan 49503 , United States
| | - T Chris Gamblin
- Department of Molecular Biosciences , University of Kansas , 1200 Sunnyside Ave , Lawrence , Kansas 66045 , United States
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10
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Zinc Induces Temperature-Dependent Reversible Self-Assembly of Tau. J Mol Biol 2018; 431:687-695. [PMID: 30580037 DOI: 10.1016/j.jmb.2018.12.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 12/14/2018] [Accepted: 12/14/2018] [Indexed: 11/22/2022]
Abstract
Tau is an intrinsically disordered microtubule-associated protein that is implicated in several neurodegenerative disorders called tauopathies. In these diseases, Tau is found in the form of intracellular inclusions that consist of aggregated paired helical filaments (PHFs) in neurons. Given the importance of this irreversible PHF formation in neurodegenerative disease, Tau aggregation has been extensively studied. Several different factors, such as mutations or post translational modifications, have been shown to influence the formation of late-stage non-reversible Tau aggregates. It was recently shown that zinc ions accelerated heparin-induced oligomerization of Tau constructs. Indeed, in vitro studies of PHFs have usually been performed in the presence of additional co-factors, such as heparin, in order to accelerate their formation. Using turbidimetry, we investigated the impact of zinc ions on Tau in the absence of heparin and found that zinc is able to induce a temperature-dependent reversible oligomerization of Tau. The obtained oligomers were not amyloid-like and dissociated instantly following zinc chelation or a temperature decrease. Finally, a combination of isothermal titration calorimetry and dynamic light scattering experiments showed zinc binding to a high-affinity binding site and three low-affinity sites on Tau, accompanied by a change in Tau folding. Altogether, our findings stress the importance of zinc in Tau oligomerization. This newly identified Zn-induced oligomerization mechanism may be a part of a pathway different of and concurrent to Tau aggregation cascade leading to PHF formation.
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11
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A Conserved Cytoskeletal Signaling Cascade Mediates Neurotoxicity of FTDP-17 Tau Mutations In Vivo. J Neurosci 2017; 38:108-119. [PMID: 29138281 DOI: 10.1523/jneurosci.1550-17.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 10/27/2017] [Accepted: 10/31/2017] [Indexed: 11/21/2022] Open
Abstract
The microtubule binding protein tau is strongly implicated in multiple neurodegenerative disorders, including frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), which is caused by mutations in tau. In vitro, FTDP-17 mutant versions of tau can reduce microtubule binding and increase the aggregation of tau, but the mechanism by which these mutations promote disease in vivo is not clear. Here we take a combined biochemical and in vivo modeling approach to define functional properties of tau driving neurotoxicity in vivo We express wild-type human tau and five FTDP-17 mutant forms of tau in Drosophila using a site-directed insertion strategy to ensure equivalent levels of expression. We then analyze multiple markers of neurodegeneration and neurotoxicity in transgenic animals, including analysis of both males and females. We find that FTDP-17 mutations act to enhance phosphorylation of tau and thus promote neurotoxicity in an in vivo setting. Further, we demonstrate that phosphorylation-dependent excess stabilization of the actin cytoskeleton is a key phosphorylation-dependent mediator of the toxicity of wild-type tau and of all the FTDP-17 mutants tested. Finally, we show that important downstream pathways, including autophagy and the unfolded protein response, are coregulated with neurotoxicity and actin cytoskeletal stabilization in brains of flies expressing wild-type human and various FTDP-17 tau mutants, supporting a conserved mechanism of neurotoxicity of wild-type tau and FTDP-17 mutant tau in disease pathogenesis.SIGNIFICANCE STATEMENT The microtubule protein tau aggregates and forms insoluble inclusion bodies known as neurofibrillary tangles in the brain tissue of patients with a variety of neurodegenerative disorders, including Alzheimer's disease. The tau protein is thus widely felt to play a key role in promoting neurodegeneration. However, precisely how tau becomes toxic is unclear. Here we capitalize on an "experiment of nature" in which rare missense mutations in tau cause familial neurodegeneration and neurofibrillary tangle formation. By comparing the biochemical activities of different tau mutations with their in vivo toxicity in a well controlled Drosophila model system, we find that all mutations tested increase phosphorylation of tau and trigger a cascade of neurotoxicity critically impinging on the integrity of the actin cytoskeleton.
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