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Zheng H, Sun H, Cai Q, Tai HC. The Enigma of Tau Protein Aggregation: Mechanistic Insights and Future Challenges. Int J Mol Sci 2024; 25:4969. [PMID: 38732197 PMCID: PMC11084794 DOI: 10.3390/ijms25094969] [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: 03/30/2024] [Revised: 04/20/2024] [Accepted: 04/23/2024] [Indexed: 05/13/2024] Open
Abstract
Tau protein misfolding and aggregation are pathological hallmarks of Alzheimer's disease and over twenty neurodegenerative disorders. However, the molecular mechanisms of tau aggregation in vivo remain incompletely understood. There are two types of tau aggregates in the brain: soluble aggregates (oligomers and protofibrils) and insoluble filaments (fibrils). Compared to filamentous aggregates, soluble aggregates are more toxic and exhibit prion-like transmission, providing seeds for templated misfolding. Curiously, in its native state, tau is a highly soluble, heat-stable protein that does not form fibrils by itself, not even when hyperphosphorylated. In vitro studies have found that negatively charged molecules such as heparin, RNA, or arachidonic acid are generally required to induce tau aggregation. Two recent breakthroughs have provided new insights into tau aggregation mechanisms. First, as an intrinsically disordered protein, tau is found to undergo liquid-liquid phase separation (LLPS) both in vitro and inside cells. Second, cryo-electron microscopy has revealed diverse fibrillar tau conformations associated with different neurodegenerative disorders. Nonetheless, only the fibrillar core is structurally resolved, and the remainder of the protein appears as a "fuzzy coat". From this review, it appears that further studies are required (1) to clarify the role of LLPS in tau aggregation; (2) to unveil the structural features of soluble tau aggregates; (3) to understand the involvement of fuzzy coat regions in oligomer and fibril formation.
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Affiliation(s)
| | | | | | - Hwan-Ching Tai
- State Key Laboratory of Vaccines for Infectious Diseases, Xiang An Biomedicine Laboratory, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Innovation Platform for Industry-Education Integration in Vaccine Research, School of Public Health, Xiamen University, Xiamen 361102, China
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Violet M, Chauderlier A, Delattre L, Tardivel M, Chouala MS, Sultan A, Marciniak E, Humez S, Binder L, Kayed R, Lefebvre B, Bonnefoy E, Buée L, Galas MC. Prefibrillar Tau oligomers alter the nucleic acid protective function of Tau in hippocampal neurons in vivo. Neurobiol Dis 2015; 82:540-551. [PMID: 26385829 DOI: 10.1016/j.nbd.2015.09.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 07/09/2015] [Accepted: 09/13/2015] [Indexed: 01/05/2023] Open
Abstract
The accumulation of DNA and RNA oxidative damage is observed in cortical and hippocampal neurons from Alzheimer's disease (AD) brains at early stages of pathology. We recently reported that Tau is a key nuclear player in the protection of neuronal nucleic acid integrity in vivo under physiological conditions and hyperthermia, a strong inducer of oxidative stress. In a mouse model of tauopathy (THY-Tau22), we demonstrate that hyperthermia selectively induces nucleic acid oxidative damage and nucleic acid strand breaks in the nucleus and cytoplasm of hippocampal neurons that display early Tau phosphorylation but no Tau fibrils. Nucleic acid-damaged neurons were exclusively immunoreactive for prefibrillar Tau oligomers. A similar association between prefibrillar Tau oligomers and nucleic acid oxidative damage was observed in AD brains. Pretreatment with Methylene Blue (MB), a Tau aggregation inhibitor and a redox cycler, reduced hyperthermia-induced Tau oligomerization as well as nucleic acid damage. This study clearly highlights the existence of an early and critical time frame for hyperthermia-induced Tau oligomerization, which most likely occurs through increased oxidative stress, and nucleic acid vulnerability during the progression of Tau pathology. These results suggest that at early stages of AD, Tau oligomerization triggers the loss of the nucleic acid protective function of monomeric Tau. This study highlights the existence of a short therapeutic window in which to prevent the formation of pathological forms of Tau and their harmful consequences on nucleic acid integrity during the progression of Tau pathology.
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Affiliation(s)
- Marie Violet
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Alban Chauderlier
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Lucie Delattre
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Meryem Tardivel
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Meliza Sendid Chouala
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Audrey Sultan
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Elodie Marciniak
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Sandrine Humez
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Lester Binder
- Department of Translational Science & Molecular Medicine, College of Human Medicine, Michigan State University, 333 Bostwick Ave. NE, Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Rakez Kayed
- Department of Neurology, George and Cynthia Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, 301 University Blvd, Medical Research Building, Room 10.138C, Galveston, TX 77555-1045, USA; Department of Neuroscience & Cell Biology, George and Cynthia Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, 301 University Blvd, Medical Research Building, Room 10.138C, Galveston, TX 77555-1045, USA
| | - Bruno Lefebvre
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Eliette Bonnefoy
- Inserm UMRS 1007, Université Paris Descartes, 45 rue des Saints Pères, 75006 Paris Cedex 06, France
| | - Luc Buée
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France
| | - Marie-Christine Galas
- Inserm, UMRS1172, JPArc, Alzheimer & Tauopathies, 1 rue Polonovski, 59045 Lille, France; Université de Lille, Faculté de Médecine, Lille, France; CHRU, Memory Clinic, Lille, France.
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Walker S, Ullman O, Stultz CM. Using intramolecular disulfide bonds in tau protein to deduce structural features of aggregation-resistant conformations. J Biol Chem 2012; 287:9591-600. [PMID: 22291015 PMCID: PMC3308815 DOI: 10.1074/jbc.m111.336107] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 01/17/2012] [Indexed: 01/11/2023] Open
Abstract
Because tau aggregation likely plays a role in a number of neurodegenerative diseases, understanding the processes that affect tau aggregation is of considerable importance. One factor that has been shown to influence the aggregation propensity is the oxidation state of the protein itself. Tau protein, which contains two naturally occurring cysteine residues, can form both intermolecular disulfide bonds and intramolecular disulfide bonds. Several studies suggest that intermolecular disulfide bonds can promote tau aggregation in vitro. By contrast, although there are data to suggest that intramolecular disulfide bond formation retards tau aggregation in vitro, the precise mechanism underlying this observation remains unclear. While it has been hypothesized that a single intramolecular disulfide bond in tau leads to compact conformations that cannot form extended structure consistent with tau fibrils, there are few data to support this conjecture. In the present study we generate oxidized forms of the truncation mutant, K18, which contains all four microtubule binding repeats, and isolate the monomeric fraction, which corresponds to K18 monomers that have a single intramolecular disulfide bond. We study the aggregation propensity of the oxidized monomeric fraction and relate these data to an atomistic model of the K18 unfolded ensemble. Our results argue that the main effect of intramolecular disulfide bond formation is to preferentially stabilize conformers within the unfolded ensemble that place the aggregation-prone tau subsequences, PHF6* and PHF6, in conformations that are inconsistent with the formation of cross-β-structure. These data further our understanding of the precise structural features that retard tau aggregation.
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Affiliation(s)
| | | | - Collin M. Stultz
- From the Research Laboratory of Electronics
- the Harvard-MIT Division of Health Sciences and Technology and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307
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