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Alhadidy MM, Kanaan NM. Biochemical approaches to assess the impact of post-translational modifications on pathogenic tau conformations using recombinant protein. Biochem Soc Trans 2024; 52:301-318. [PMID: 38348781 PMCID: PMC10903483 DOI: 10.1042/bst20230596] [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: 11/10/2023] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/29/2024]
Abstract
Tau protein is associated with many neurodegenerative disorders known as tauopathies. Aggregates of tau are thought of as a main contributor to neurodegeneration in these diseases. Increasingly, evidence points to earlier, soluble conformations of abnormally modified monomers and multimeric tau as toxic forms of tau. The biological processes driving tau from physiological species to pathogenic conformations remain poorly understood, but certain avenues are currently under investigation including the functional consequences of various pathological tau changes (e.g. mutations, post-translational modifications (PTMs), and protein-protein interactions). PTMs can regulate several aspects of tau biology such as proteasomal and autophagic clearance, solubility, and aggregation. Moreover, PTMs can contribute to the transition of tau from normal to pathogenic conformations. However, our understating of how PTMs specifically regulate the transition of tau into pathogenic conformations is partly impeded by the relative lack of structured frameworks to assess and quantify these conformations. In this review, we describe a set of approaches that includes several in vitro assays to determine the contribution of PTMs to tau's transition into known pathogenic conformations. The approaches begin with different methods to create recombinant tau proteins carrying specific PTMs followed by validation of the PTMs status. Then, we describe a set of biochemical and biophysical assays that assess the contribution of a given PTM to different tau conformations, including aggregation, oligomerization, exposure of the phosphatase-activating domain, and seeding. Together, these approaches can facilitate the advancement of our understanding of the relationships between PTMs and tau conformations.
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Affiliation(s)
- Mohammed M. Alhadidy
- Department of Translational Neuroscience, College of Human Medicine, Michigan State University, Grand Rapids, MI, U.S.A
- Neuroscience Program, Michigan State University, East Lansing, MI, U.S.A
| | - Nicholas M. Kanaan
- Department of Translational Neuroscience, College of Human Medicine, Michigan State University, Grand Rapids, MI, U.S.A
- Neuroscience Program, Michigan State University, East Lansing, MI, U.S.A
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Christensen KR, Combs B, Richards C, Grabinski T, Alhadidy MM, Kanaan NM. Phosphomimetics at Ser199/Ser202/Thr205 in Tau Impairs Axonal Transport in Rat Hippocampal Neurons. Mol Neurobiol 2023; 60:3423-3438. [PMID: 36859689 PMCID: PMC10122714 DOI: 10.1007/s12035-023-03281-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/16/2023] [Indexed: 03/03/2023]
Abstract
Our understanding of the biological functions of the tau protein now includes its role as a scaffolding protein involved in signaling regulation, which also has implications for tau-mediated dysfunction and degeneration in Alzheimer's disease and other tauopathies. Recently, we found that pseudophosphorylation at sites linked to the pathology-associated AT8 phosphoepitope of tau disrupts normal fast axonal transport through a protein phosphatase 1 (PP1)-dependent pathway in squid axoplasm. Activation of the pathway and the resulting transport deficits required tau's N-terminal phosphatase-activating domain (PAD) and PP1 but the connection between tau and PP1 was not well defined. Here, we studied functional interactions between tau and PP1 isoforms and their effects on axonal transport in mammalian neurons. First, we found that wild-type tau interacted with PP1α and PP1γ primarily through its microtubule-binding repeat domain. Pseudophosphorylation of tau at S199/S202/T205 (psTau) increased PAD exposure, enhanced interactions with PP1γ, and increased active PP1γ levels in mammalian cells. Expression of psTau also significantly impaired axonal transport in primary rat hippocampal neurons. Deletion of PAD in psTau significantly reduced the interaction with PP1γ, eliminated increases of active PP1γ levels, and rescued axonal transport impairment in neurons. These data suggest that a functional consequence of phosphorylation within S199-T205 in tau, which occurs in AD and several other tauopathies, may be aberrant interaction with and activation of PP1γ and subsequent axonal transport disruption in a PAD-dependent fashion.
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Affiliation(s)
- Kyle R Christensen
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Benjamin Combs
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Collin Richards
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Tessa Grabinski
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
| | - Mohammed M Alhadidy
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Nicholas M Kanaan
- Department of Translational Neuroscience, Michigan State University, 400 Monroe Ave NW, Grand Rapids, MI, 49503, USA.
- Neuroscience Program, Michigan State University, East Lansing, MI, 48824, USA.
- Hauenstein Neuroscience Center, Mercy Health Saint Mary's, Grand Rapids, MI, 49503, USA.
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Ma N, Liang Y, Yue L, Liu P, Xu Y, Zhu C. The identities of insulin signaling pathway are affected by overexpression of Tau and its phosphorylation form. Front Aging Neurosci 2022; 14:1057281. [PMID: 36589543 PMCID: PMC9800792 DOI: 10.3389/fnagi.2022.1057281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 11/25/2022] [Indexed: 12/23/2022] Open
Abstract
Introduction Hyperphosphorylated Tau formed neurofibrillary tangles was one of the major neuropathological hallmarks of Alzheimer's disease (AD). Dysfunctional insulin signaling in brain is involved in AD. However, the effect of Tau pathology on brain insulin resistance remains unclear. This study explored the effects of overexpressing wild-type Tau (WTau) or Tau with pseudo-phosphorylation at AT8 residues (PTau) on the insulin signaling pathway (ISP). Methods 293T cells or SY5Y cells overexpressing WTau or PTau were treated with or without insulin. The elements in ISP or the regulators of IPS were analyzed by immunoblotting, immunofluorescent staining and co-immunoprecipitation. Akt inhibitor MK2206 was used for evaluating the insulin signaling to downstream of mTOR in Tau overexpressing cells. The effects of anti-aging drug lonafarnib on ISP in WTau or PTau cells were also analyzed with immunoblotting. Considering lonafarnib is an inhibitor of FTase, the states of Rhes, one of FTase substrate in WTau or PTau cells were analyzed by drug affinity responsive target stability (DARTS) assay and the cellular thermal shift assay (CETSA). Results WTau or PTau overexpression in cells upregulated basal activity of elements in ISP in general. However, overexpression of WTau or PTau suppressed the ISP signaling transmission responses induced by insulin simulation, appearing relative higher response of IRS-1 phosphorylation at tyrosine 612 (IRS-1 p612) in upstream IPS, but a lower phosphorylation response of downstream IPS including mTOR, and its targets 4EPB1 and S6. This dysregulation of insulin evoked signaling transmission was more obvious in PTau cells. Suppressing Akt with MK2206 could compromise the levels of p-S6 and p-mTOR in WTau or PTau cells. Moreover, the changes of phosphatases detected in WTau and PTau cells may be related to ISP dysfunction. In addition, the effects of lonafarnib on the ISP in SY5Y cells with WTau and PTau overexpression were tested, which showed that lonafarnib treatment resulted in reducing the active levels of ISP elements in PTau cells but not in WTau cells. The differential effects are probably due to Tau phosphorylation modulating lonafarnib-induced alterations in Rhes, as revealed by DARTS assay. Conclusion and discussion Overexpression of Tau or Tau with pseudo-phosphorylation at AT8 residues could cause an upregulation of the basal/tonic ISP, but a suppression of insulin induced the phasic activation of ISP. This dysfunction of ISP was more obvious in cells overexpressing pseudo-phosphorylated Tau. These results implied that the dysfunction of ISP caused by Tau overexpression might impair the physiological fluctuation of neuronal functions in AD. The different effects of lonafarnib on ISP between WTau and PTau cells, indicating that Tau phosphorylation mediates an additional effect on ISP. This study provided a potential linkage of abnormal expression and phosphorylation of Tau to the ISP dysfunction in AD.
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Opportunities and challenges in delivering biologics for Alzheimer's disease by low-intensity ultrasound. Adv Drug Deliv Rev 2022; 189:114517. [PMID: 36030018 DOI: 10.1016/j.addr.2022.114517] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/15/2022] [Accepted: 08/19/2022] [Indexed: 01/24/2023]
Abstract
Low-intensity ultrasound combined with intravenously injected microbubbles (US+MB) is a novel treatment modality for brain disorders, including Alzheimer's disease (AD), safely and transiently allowing therapeutic agents to overcome the blood-brain barrier (BBB) that constitutes a major barrier for therapeutic agents. Here, we first provide an update on immunotherapies in AD and how US+MB has been applied to AD mouse models and in clinical trials, considering the ultrasound and microbubble parameter space. In the second half of the review, we compare different in vitro BBB models and discuss strategies for combining US+MB with BBB modulators (targeting molecules such as claudin-5), and highlight the insight provided by super-resolution microscopy. Finally, we conclude with a short discussion on how in vitro findings can inform the design of animal studies, and how the insight gained may aid treatment optimization in the clinical ultrasound space.
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Alyenbaawi H, Allison WT, Mok SA. Prion-Like Propagation Mechanisms in Tauopathies and Traumatic Brain Injury: Challenges and Prospects. Biomolecules 2020; 10:E1487. [PMID: 33121065 PMCID: PMC7692808 DOI: 10.3390/biom10111487] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/22/2020] [Accepted: 10/23/2020] [Indexed: 12/23/2022] Open
Abstract
The accumulation of tau protein in the form of filamentous aggregates is a hallmark of many neurodegenerative diseases such as Alzheimer's disease (AD) and chronic traumatic encephalopathy (CTE). These dementias share traumatic brain injury (TBI) as a prominent risk factor. Tau aggregates can transfer between cells and tissues in a "prion-like" manner, where they initiate the templated misfolding of normal tau molecules. This enables the spread of tau pathology to distinct parts of the brain. The evidence that tauopathies spread via prion-like mechanisms is considerable, but work detailing the mechanisms of spread has mostly used in vitro platforms that cannot fully reveal the tissue-level vectors or etiology of progression. We review these issues and then briefly use TBI and CTE as a case study to illustrate aspects of tauopathy that warrant further attention in vivo. These include seizures and sleep/wake disturbances, emphasizing the urgent need for improved animal models. Dissecting these mechanisms of tauopathy progression continues to provide fresh inspiration for the design of diagnostic and therapeutic approaches.
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Affiliation(s)
- Hadeel Alyenbaawi
- Centre for Prions & Protein Folding Disease, University of Alberta, Edmonton, AB T6G 2M8, Canada; (H.A.); (W.T.A.)
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Medical Laboratories, Majmaah University, Majmaah 11952, Saudi Arabia
| | - W. Ted Allison
- Centre for Prions & Protein Folding Disease, University of Alberta, Edmonton, AB T6G 2M8, Canada; (H.A.); (W.T.A.)
- Department of Medical Genetics, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Sue-Ann Mok
- Centre for Prions & Protein Folding Disease, University of Alberta, Edmonton, AB T6G 2M8, Canada; (H.A.); (W.T.A.)
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Xia Y, Prokop S, Gorion KMM, Kim JD, Sorrentino ZA, Bell BM, Manaois AN, Chakrabarty P, Davies P, Giasson BI. Tau Ser208 phosphorylation promotes aggregation and reveals neuropathologic diversity in Alzheimer's disease and other tauopathies. Acta Neuropathol Commun 2020; 8:88. [PMID: 32571418 PMCID: PMC7310041 DOI: 10.1186/s40478-020-00967-w] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/12/2020] [Indexed: 12/11/2022] Open
Abstract
Tau protein abnormally aggregates in tauopathies, a diverse group of neurologic diseases that includes Alzheimer’s disease (AD). In early stages of disease, tau becomes hyperphosphorylated and mislocalized, which can contribute to its aggregation and toxicity. We demonstrate that tau phosphorylation at Ser208 (pSer208) promotes microtubule dysfunction and tau aggregation in cultured cells. Comparative assessment of the epitopes recognized by antibodies AT8, CP13, and 7F2 demonstrates that CP13 and 7F2 are specific for tau phosphorylation at Ser202 and Thr205, respectively, independently of the phosphorylation state of adjacent phosphorylation sites. Supporting the involvement of pSer208 in tau pathology, a novel monoclonal antibody 3G12 specific for tau phosphorylation at Ser208 revealed strong reactivity of tau inclusions in the brains of PS19 and rTg4510 transgenic mouse models of tauopathy. 3G12 also labelled neurofibrillary tangles in brains of patients with AD but revealed differential staining compared to CP13 and 7F2 for other types of tau pathologies such as in neuropil threads and neuritic plaques in AD, tufted astrocytes in progressive supranuclear palsy and astrocytic plaques in corticobasal degeneration. These results support the hypothesis that tau phosphorylation at Ser208 strongly contributes to unique types of tau aggregation and may be a reliable marker for the presence of mature neurofibrillary tangles.
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Endogenous oligodendroglial alpha-synuclein and TPPP/p25α orchestrate alpha-synuclein pathology in experimental multiple system atrophy models. Acta Neuropathol 2019; 138:415-441. [PMID: 31011860 PMCID: PMC7289399 DOI: 10.1007/s00401-019-02014-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 04/03/2019] [Accepted: 04/15/2019] [Indexed: 12/11/2022]
Abstract
Multiple system atrophy (MSA) is characterized by the presence of distinctive glial cytoplasmic inclusions (GCIs) within oligodendrocytes that contain the neuronal protein alpha-synuclein (aSyn) and the oligodendroglia-specific phosphoprotein TPPP/p25α. However, the role of oligodendroglial aSyn and p25α in the formation of aSyn-rich GCIs remains unclear. To address this conundrum, we have applied human aSyn (haSyn) pre-formed fibrils (PFFs) to rat wild-type (WT)-, haSyn-, or p25α-overexpressing oligodendroglial cells and to primary differentiated oligodendrocytes derived from WT, knockout (KO)-aSyn, and PLP-haSyn-transgenic mice. HaSyn PFFs are readily taken up by oligodendroglial cells and can recruit minute amounts of endogenous aSyn into the formation of insoluble, highly aggregated, pathological assemblies. The overexpression of haSyn or p25α accelerates the recruitment of endogenous protein and the generation of such aberrant species. In haSyn PFF-treated primary oligodendrocytes, the microtubule and myelin networks are disrupted, thus recapitulating a pathological hallmark of MSA, in a manner totally dependent upon the seeding of endogenous aSyn. Furthermore, using oligodendroglial and primary cortical cultures, we demonstrated that pathology-related S129 aSyn phosphorylation depends on aSyn and p25α protein load and may involve different aSyn “strains” present in oligodendroglial and neuronal synucleinopathies. Importantly, this hypothesis was further supported by data obtained from human post-mortem brain material derived from patients with MSA and dementia with Lewy bodies. Finally, delivery of haSyn PFFs into the mouse brain led to the formation of aberrant aSyn forms, including the endogenous protein, within oligodendroglia and evoked myelin decompaction in WT mice, but not in KO-aSyn mice. This line of research highlights the role of endogenous aSyn and p25α in the formation of pathological aSyn assemblies in oligodendrocytes and provides in vivo evidence of the contribution of oligodendroglial aSyn in the establishment of aSyn pathology in MSA.
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Yeboah F, Kim TE, Bill A, Dettmer U. Dynamic behaviors of α-synuclein and tau in the cellular context: New mechanistic insights and therapeutic opportunities in neurodegeneration. Neurobiol Dis 2019; 132:104543. [PMID: 31351173 DOI: 10.1016/j.nbd.2019.104543] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 07/18/2019] [Accepted: 07/22/2019] [Indexed: 10/26/2022] Open
Abstract
α-Synuclein (αS) and tau have a lot in common. Dyshomeostasis and aggregation of both proteins are central in the pathogenesis of neurodegenerative diseases: Parkinson's disease, dementia with Lewy bodies, multi-system atrophy and other 'synucleinopathies' in the case of αS; Alzheimer's disease, frontotemporal dementia, progressive supranuclear palsy and other 'tauopathies' in the case of tau. The aggregated states of αS and tau are found to be (hyper)phosphorylated, but the relevance of the phosphorylation in health or disease is not well understood. Both tau and αS are typically characterized as 'intrinsically disordered' proteins, while both engage in transient interactions with cellular components, thereby undergoing structural changes and context-specific folding. αS transiently binds to (synaptic) vesicles forming a membrane-induced amphipathic helix; tau transiently interacts with microtubules forming an 'extended structure'. The regulation and exact nature of the interactions are not fully understood. Here we review recent and previous insights into the dynamic, transient nature of αS and tau with regard to the mode of interaction with their targets, the dwell-time while bound, and the cis and trans factors underlying the frequent switching between bound and unbound states. These aspects are intimately linked to hypotheses on how subtle changes in the transient behaviors may trigger the earliest steps in the pathogenesis of the respective brain diseases. Based on a deeper understanding of transient αS and tau conformations in the cellular context, new therapeutic strategies may emerge, and it may become clearer why existing approaches have failed or how they could be optimized.
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Affiliation(s)
- Fred Yeboah
- Novartis Institute for Biomedical Research, Chemical Biology and Therapeutics, Cambridge, MA 02139, USA
| | - Tae-Eun Kim
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Anke Bill
- Novartis Institute for Biomedical Research, Chemical Biology and Therapeutics, Cambridge, MA 02139, USA.
| | - Ulf Dettmer
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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Sato C, Barthélemy NR, Mawuenyega KG, Patterson BW, Gordon BA, Jockel-Balsarotti J, Sullivan M, Crisp MJ, Kasten T, Kirmess KM, Kanaan NM, Yarasheski KE, Baker-Nigh A, Benzinger TLS, Miller TM, Karch CM, Bateman RJ. Tau Kinetics in Neurons and the Human Central Nervous System. Neuron 2019; 97:1284-1298.e7. [PMID: 29566794 DOI: 10.1016/j.neuron.2018.02.015] [Citation(s) in RCA: 290] [Impact Index Per Article: 58.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 01/17/2018] [Accepted: 02/20/2018] [Indexed: 01/21/2023]
Abstract
We developed stable isotope labeling and mass spectrometry approaches to measure the kinetics of multiple isoforms and fragments of tau in the human central nervous system (CNS) and in human induced pluripotent stem cell (iPSC)-derived neurons. Newly synthesized tau is truncated and released from human neurons in 3 days. Although most tau proteins have similar turnover, 4R tau isoforms and phosphorylated forms of tau exhibit faster turnover rates, suggesting unique processing of these forms that may have independent biological activities. The half-life of tau in control human iPSC-derived neurons is 6.74 ± 0.45 days and in human CNS is 23 ± 6.4 days. In cognitively normal and Alzheimer's disease participants, the production rate of tau positively correlates with the amount of amyloid plaques, indicating a biological link between amyloid plaques and tau physiology.
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Affiliation(s)
- Chihiro Sato
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Nicolas R Barthélemy
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Kwasi G Mawuenyega
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Bruce W Patterson
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Brian A Gordon
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | | | - Melissa Sullivan
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Matthew J Crisp
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tom Kasten
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Kristopher M Kirmess
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Nicholas M Kanaan
- Michigan State University, College of Human Medicine, Department of Translational Science and Molecular Medicine, Grand Rapids, MI 49503, USA
| | - Kevin E Yarasheski
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Alaina Baker-Nigh
- Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tammie L S Benzinger
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Timothy M Miller
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Celeste M Karch
- Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Randall J Bateman
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA; Charles F. and Joanne Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Minimalistic in vitro systems for investigating tau pathology. J Neurosci Methods 2018; 319:69-76. [PMID: 30278185 DOI: 10.1016/j.jneumeth.2018.09.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/27/2018] [Accepted: 09/28/2018] [Indexed: 01/30/2023]
Abstract
Neurofibrillary tangles, formed of hyperphosphorylated, misfolded tau accumulations, are a pathological hallmark of neurodegenerative diseases such as Alzheimer's disease (AD) and frontotemporal dementia. The neuroanatomical localisation of tau pathology in AD brains of different disease stages suggests that tau tangle pathology is spreading throughout the brain along connected neuronal circuits. Pathogenic tau can act as a prion-like seed, inducing the misfolding of native tau and leading to disease propagation throughout the brain. However, it is not yet fully understood how tau spreads between individual neurons or brain regions. Here, we review the models for investigating tau propagation in vitro, and summarise the findings from key studies into the mechanisms of tau pathology propagation in disease.
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11
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Cao L, Liang Y, Liu Y, Xu Y, Wan W, Zhu C. Pseudo-phosphorylation at AT8 epitopes regulates the tau truncation at aspartate 421. Exp Cell Res 2018; 370:103-115. [PMID: 29908160 DOI: 10.1016/j.yexcr.2018.06.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 06/10/2018] [Accepted: 06/12/2018] [Indexed: 12/21/2022]
Abstract
Tau pathology in Alzheimer's disease (AD) includes hyperphosphorylation and truncation of tau. Phosphorylation at S422 is found to suppress truncation of tau at D421 that leading to the generation of ΔTau. However, the interrelation between hyperphosphorylation and generation of ΔTau in AD remains elusive. In current study, staurosporine (Stau) induced ΔTau generation by caspases in SH-SY5Y cells with tau overexpression was found to be accompanied by a dramatic dephosphorylation at S422 and the epitope of the diagnostic antibody AT8 (S199 + S202 + T205), but a moderate dephosphorylation of PHF1 (S396 + S404) epitope. Therefore, to explore the effect of AT8 epitope on tau truncation, the residues in AT8 epitope were mutated to produce "pseudo-phosphorylated" (AT8E) or "pseudo-unphosphorylated" (AT8A) tau constructs. With Stau treatment, the generation of ΔTau from tau-AT8E was significantly attenuated comparing with that from tau-AT8A, which was S422-independent in that addition of S422A mutation still preserved this effect. Interestingly, this modulatory effect was able to be reversed by addition of PHF1E mutation. Moreover, treating the crude tau extracts with recombinant caspase-3 in vitro, also showed that ΔTau level was suppressed by AT8E, and potentiated by AT8E + PHF1E. The results primarily revealed the modulating effects of phosphorylation on ΔTau generation which may have potential implications in tau pathological processes and therapeutic intervention.
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Affiliation(s)
- Lan Cao
- State Key Laboratory of Medical Neurobiology & Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yan Liang
- State Key Laboratory of Medical Neurobiology & Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yunsheng Liu
- State Key Laboratory of Medical Neurobiology & Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yuxia Xu
- State Key Laboratory of Medical Neurobiology & Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, China
| | - Wenbin Wan
- Department of Neurology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Cuiqing Zhu
- State Key Laboratory of Medical Neurobiology & Institutes of Brain Science, Shanghai Medical College, Fudan University, Shanghai, China.
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Piccardo P, King D, Brown D, Barron RM. Variable tau accumulation in murine models with abnormal prion protein deposits. J Neurol Sci 2017; 383:142-150. [PMID: 29246602 PMCID: PMC6381323 DOI: 10.1016/j.jns.2017.10.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 10/04/2017] [Accepted: 10/25/2017] [Indexed: 12/26/2022]
Abstract
The conversion of cellular prion protein (PrP) into a misfolded isoform is central to the development of prion diseases. However, the heterogeneous phenotypes observed in prion disease may be linked with the presence of other misfolded proteins in the brain. While hyperphosphorylated tau (p.tau) is characteristic of Alzheimer's disease (AD), p.tau is also observed in human prion diseases. To explore this association in the absence of potential effects due to aging, drug treatment, agonal stage and postmortem delay we analyzed p.tau and PrP immunopositivity in mouse models. Analyses were performed on mice inoculated with prion agents, and mice with PrP amyloid in the absence of prion disease. We observed that p.tau was consistently present in animals with prion infectivity (models that transmit disease upon serial passage). In contrast, p.tau was very rarely observed or absent in mice with PrP amyloid plaques in the absence of prion replication. These data indicate that the formation of p.tau is not linked to deposition of misfolded PrP, but suggest that the interaction between replication of infectivity and host factors regulate the formation of p.tau and may contribute to the heterogeneous phenotype of prion diseases.
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Affiliation(s)
- Pedro Piccardo
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, United Kingdom.
| | - Declan King
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, United Kingdom
| | - Deborah Brown
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, United Kingdom
| | - Rona M Barron
- The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, Scotland, United Kingdom
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Zabik NL, Imhof MM, Martic-Milne S. Structural evaluations of tau protein conformation: methodologies and approaches. Biochem Cell Biol 2017; 95:338-349. [PMID: 28278386 DOI: 10.1139/bcb-2016-0227] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Protein-misfolding diseases are based on a common principle of aggregation initiated by intra- and inter-molecular contacts. The structural and conformational changes induced by biochemical transformations such as post-translational modifications (PTMs), often lead to protein unfolding and misfolding. Thus, these order-to-disorder or disorder-to-order transitions may regulate cellular function. Tau, a neuronal protein, regulates microtubule (MT) structure and overall cellular integrity. However, misfolded tau modified by PTMs results in MT destabilization, toxic tau aggregate formation, and ultimately cell death, leading to neurodegeneration. Currently, the lack of structural information surrounding tau severely limits understanding of neurodegeneration. This minireview focuses on the current methodologies and approaches aimed at probing tau conformation and the role of conformation in various aspects of tau biochemistry. The recent applications of nuclear magnetic resonance, mass spectrometry, Förster resonance electron transfer, and molecular dynamics simulations toward structural analysis of conformational landscapes of tau will be described. The strategies developed for structural evaluation of tau may significantly improve our understanding of misfolding diseases.
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Affiliation(s)
- Nicole L Zabik
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA.,Department of Chemistry, Oakland University, Rochester, MI 48309, USA
| | - Matthew M Imhof
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA.,Department of Chemistry, Oakland University, Rochester, MI 48309, USA
| | - Sanela Martic-Milne
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA.,Department of Chemistry, Oakland University, Rochester, MI 48309, USA
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Prokopovich DV, Whittaker JW, Muthee MM, Ahmed A, Larini L. Impact of Phosphorylation and Pseudophosphorylation on the Early Stages of Aggregation of the Microtubule-Associated Protein Tau. J Phys Chem B 2017; 121:2095-2103. [PMID: 28218850 DOI: 10.1021/acs.jpcb.7b00194] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The microtubule-associated protein tau regulates the stability of microtubules within neurons in the central nervous system. In turn, microtubules are responsible for the remodeling of the cytoskeleton that ultimately leads to the formation or pruning of new connections among neurons. As a consequence, dysfunction of tau is associated with many forms of dementia as well as Alzheimer's disease. In the brain, tau activity is regulated by its phosphorylation state. Phosphorylation is a post-translational modification of proteins that adds a phosphate group to the side chain of an amino acid. Phosphorylation at key locations in the tau sequence leads to a higher or lower affinity for microtubules. In Alzheimer's disease, tau is present in an abnormal phosphorylation state. However, studying the effect of phosphorylation experimentally has been extremely challenging as there is no viable way of exactly selecting the location and the number of phosphorylated sites. For this reason, researchers have turned to pseudophosphorylation. In this technique, actual phosphorylation is mimicked by mutating the selected amino acid into glutamate or aspartate. Whether this methodology is equivalent to actual phosphorylation is still open to debate. In this study, we will show that phosphorylation and pseudophosphorylation are not exactly equivalent. Although for larger aggregates the two techniques lead to similar structures, the kinetics of the process may be altered. In addition, very little is known about the impact that this may have on the early stages of aggregation, such as nucleation and conformational rearrangement. In this study, we show that the two methods may produce a similar ensemble of conformations, even though the kinetic and chemical details that lead to it are quite different.
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Affiliation(s)
- Dmitriy V Prokopovich
- Department of Physics and ‡Center for Computational and Integrative Biology, Rutgers University-Camden , Camden, New Jersey 08102, United States
| | - John W Whittaker
- Department of Physics and ‡Center for Computational and Integrative Biology, Rutgers University-Camden , Camden, New Jersey 08102, United States
| | - Micaiah M Muthee
- Department of Physics and ‡Center for Computational and Integrative Biology, Rutgers University-Camden , Camden, New Jersey 08102, United States
| | - Azka Ahmed
- Department of Physics and ‡Center for Computational and Integrative Biology, Rutgers University-Camden , Camden, New Jersey 08102, United States
| | - Luca Larini
- Department of Physics and ‡Center for Computational and Integrative Biology, Rutgers University-Camden , Camden, New Jersey 08102, United States
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Arendt T, Stieler JT, Holzer M. Tau and tauopathies. Brain Res Bull 2016; 126:238-292. [DOI: 10.1016/j.brainresbull.2016.08.018] [Citation(s) in RCA: 333] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/31/2016] [Accepted: 08/31/2016] [Indexed: 12/11/2022]
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Moszczynski AJ, Gohar M, Volkening K, Leystra-Lantz C, Strong W, Strong MJ. Thr175-phosphorylated tau induces pathologic fibril formation via GSK3β-mediated phosphorylation of Thr231 in vitro. Neurobiol Aging 2014; 36:1590-9. [PMID: 25573097 DOI: 10.1016/j.neurobiolaging.2014.12.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Revised: 11/11/2014] [Accepted: 12/03/2014] [Indexed: 12/13/2022]
Abstract
We have previously shown that amyotrophic lateral sclerosis with cognitive impairment can be characterized by pathologic inclusions of microtubule-associated protein tau (tau) phosphorylated at Thr(175) (pThr(175)) in association with GSK3β activation. We have now examined whether pThr(175) induces GSK3β activation and whether this leads to pathologic fibril formation through Thr(231) phosphorylation. Seventy-two hours after transfection of Neuro2A cells with pseudophosphorylated green fluorescent protein-tagged 2N4R tau (Thr(175)Asp), phosphorylated kinase glycogen synthase kinase 3 beta (active GSK3β) levels were significantly increased as was pathologic fibril formation and cell death. Treatment with each of 4 GSK3β inhibitors or small hairpin RNA knockdown of GSK3β abolished fibril formation and prevented cell death. Inhibition of Thr(231) phosphorylation (Thr(231)Ala) prevented pathologic tau fibril formation, regardless of Thr(175) state, whereas Thr(231)Asp (pseudophosphorylated at Thr(231)) developed pathologic tau fibrils. Ser(235) mutations did not affect fibril formation, indicating an unprimed mechanism of Thr(231) phosphorylation. These findings suggest a mechanism of tau pathology by which pThr(175) induces GSK3β phosphorylation of Thr(231) leading to fibril formation, indicating a potential therapeutic avenue for amyotrophic lateral sclerosis with cognitive impairment.
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Affiliation(s)
- Alexander J Moszczynski
- Graduate Program in Neuroscience, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - May Gohar
- Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Kathryn Volkening
- Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Cheryl Leystra-Lantz
- Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Wendy Strong
- Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
| | - Michael J Strong
- Graduate Program in Neuroscience, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
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Tenreiro S, Eckermann K, Outeiro TF. Protein phosphorylation in neurodegeneration: friend or foe? Front Mol Neurosci 2014; 7:42. [PMID: 24860424 PMCID: PMC4026737 DOI: 10.3389/fnmol.2014.00042] [Citation(s) in RCA: 171] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 04/22/2014] [Indexed: 12/15/2022] Open
Abstract
Protein misfolding and aggregation is a common hallmark in neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), and fronto-temporal dementia (FTD). In these disorders, the misfolding and aggregation of specific proteins occurs alongside neuronal degeneration in somewhat specific brain areas, depending on the disorder and the stage of the disease. However, we still do not fully understand the mechanisms governing protein aggregation, and whether this constitutes a protective or detrimental process. In PD, alpha-synuclein (aSyn) forms protein aggregates, known as Lewy bodies, and is phosphorylated at serine 129. Other residues have also been shown to be phosphorylated, but the significance of phosphorylation in the biology and pathophysiology of the protein is still controversial. In AD and in FTD, hyperphosphorylation of tau protein causes its misfolding and aggregation. Again, our understanding of the precise consequences of tau phosphorylation in the biology and pathophysiology of the protein is still limited. Through the use of a variety of model organisms and technical approaches, we are now gaining stronger insight into the effects of phosphorylation in the behavior of these proteins. In this review, we cover recent findings in the field and discuss how targeting phosphorylation events might be used for therapeutic intervention in these devastating diseases of the nervous system.
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Affiliation(s)
- Sandra Tenreiro
- Cell and Molecular Neuroscience Unit, Instituto de Medicina Molecular Lisboa, Portugal
| | - Katrin Eckermann
- Department of Neurology, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen Göttingen, Germany
| | - Tiago F Outeiro
- Cell and Molecular Neuroscience Unit, Instituto de Medicina Molecular Lisboa, Portugal ; Instituto de Fisiologia, Faculdade de Medicina da Universidade de Lisboa Lisboa, Portugal ; Department of NeuroDegeneration and Restorative Research, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen Göttingen, Germany
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18
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Tau protein modifications and interactions: their role in function and dysfunction. Int J Mol Sci 2014; 15:4671-713. [PMID: 24646911 PMCID: PMC3975420 DOI: 10.3390/ijms15034671] [Citation(s) in RCA: 223] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 02/11/2014] [Accepted: 03/04/2014] [Indexed: 01/29/2023] Open
Abstract
Tau protein is abundant in the central nervous system and involved in microtubule assembly and stabilization. It is predominantly associated with axonal microtubules and present at lower level in dendrites where it is engaged in signaling functions. Post-translational modifications of tau and its interaction with several proteins play an important regulatory role in the physiology of tau. As a consequence of abnormal modifications and expression, tau is redistributed from neuronal processes to the soma and forms toxic oligomers or aggregated deposits. The accumulation of tau protein is increasingly recognized as the neuropathological hallmark of a number of dementia disorders known as tauopathies. Dysfunction of tau protein may contribute to collapse of cytoskeleton, thereby causing improper anterograde and retrograde movement of motor proteins and their cargos on microtubules. These disturbances in intraneuronal signaling may compromise synaptic transmission as well as trophic support mechanisms in neurons.
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Droppelmann CA, Campos-Melo D, Ishtiaq M, Volkening K, Strong MJ. RNA metabolism in ALS: When normal processes become pathological. Amyotroph Lateral Scler Frontotemporal Degener 2014; 15:321-36. [DOI: 10.3109/21678421.2014.881377] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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20
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Yuzwa SA, Cheung AH, Okon M, McIntosh LP, Vocadlo DJ. O-GlcNAc modification of tau directly inhibits its aggregation without perturbing the conformational properties of tau monomers. J Mol Biol 2014; 426:1736-52. [PMID: 24444746 DOI: 10.1016/j.jmb.2014.01.004] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 12/11/2013] [Accepted: 01/14/2014] [Indexed: 11/29/2022]
Abstract
The aggregation of the microtubule-associated protein tau into paired helical filaments to form neurofibrillary tangles constitutes one of the pathological hallmarks of Alzheimer's disease. Tau is post-translationally modified by the addition of N-acetyl-D-glucosamine O-linked to several serine and threonine residues (O-GlcNAc). Previously, increased O-GlcNAcylation of tau has been shown to block the accumulation of tau aggregates within a tauopathy mouse model. Here we show that O-GlcNAc modification of full-length human tau impairs the rate and extent of its heparin-induced aggregation without perturbing its activity toward microtubule polymerization. O-GlcNAcylation, however, does not impact the "global-fold" of tau as measured by a Förster resonance energy transfer assay. Similarly, nuclear magnetic resonance studies demonstrated that O-GlcNAcylation only minimally perturbs the local structural and dynamic features of a tau fragment (residues 353-408) spanning the last microtubule binding repeat to the major GlcNAc-acceptor Ser400. These data indicate that the inhibitory effects of O-GlcNAc on tau aggregation may result from enhanced monomer solubility or the destabilization of fibrils or soluble aggregates, rather than by altering the conformational properties of the monomeric protein. This work further underscores the potential of targeting the O-GlcNAc pathway for potential Alzheimer's disease therapeutics.
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Affiliation(s)
- Scott A Yuzwa
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6; Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6
| | - Adrienne H Cheung
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and the Michael Smith Laboratories, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
| | - Mark Okon
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and the Michael Smith Laboratories, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
| | - Lawrence P McIntosh
- Department of Biochemistry and Molecular Biology, Department of Chemistry, and the Michael Smith Laboratories, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
| | - David J Vocadlo
- Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6; Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6.
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2, 6-Diisopropylphenol Protects Against The Impairment of Learning-memory and Reduces The Hyperphosphorylation of Protein Tau Induced by Electroconvulsive Shock in The Depression Model Rats Whose Olfactory Bulbs Were Removed*. PROG BIOCHEM BIOPHYS 2012. [DOI: 10.3724/sp.j.1206.2011.00483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Duan AR, Goodson HV. Taxol-stabilized microtubules promote the formation of filaments from unmodified full-length Tau in vitro. Mol Biol Cell 2012; 23:4796-806. [PMID: 23087208 PMCID: PMC3521687 DOI: 10.1091/mbc.e12-05-0374] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Tau is a neuronal protein that stabilizes the microtubule (MT) network, but it also forms filaments associated with Alzheimer's disease. Understanding Tau-MT and Tau-Tau interactions would help to establish Tau function in health and disease. For many years, literature reports on Tau-MT binding behavior and affinity have remained surprisingly contradictory (e.g., 10-fold variation in Tau-MT affinity). Tau-Tau interactions have also been investigated, but whether MTs might affect Tau filament formation is unknown. We have addressed these issues through binding assays and microscopy. We assessed Tau-MT interactions via cosedimentation and found that the measured affinity of Tau varies greatly, depending on the experimental design and the protein concentrations used. To investigate this dependence, we used fluorescence microscopy to examine Tau-MT binding. Strikingly, we found that Taxol-stabilized MTs promote Tau filament formation without characterized Tau-filament inducers. We propose that these novel Tau filaments account for the incongruence in Tau-MT affinity measurements. Moreover, electron microscopy reveals that these filaments appear similar to the heparin-induced Alzheimer's model. These observations suggest that the MT-induced Tau filaments provide a new model for Alzheimer's studies and that MTs might play a role in the formation of Alzheimer's-associated neurofibrillary tangles.
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Affiliation(s)
- Aranda R Duan
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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23
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Combs B, Gamblin TC. FTDP-17 tau mutations induce distinct effects on aggregation and microtubule interactions. Biochemistry 2012; 51:8597-607. [PMID: 23043292 DOI: 10.1021/bi3010818] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
FTDP-17 mutations in the tau gene lead to early onset frontotemporal dementias characterized by the pathological aggregation of the microtubule-associated protein tau. Tau aggregation is closely correlated with the progression and severity of localized atrophy of certain regions in the brain. These mutations are primarily located in or near the microtubule-binding repeat regions of tau and can have vastly different effects on the protein. Some mutations have been linked to effects such as increased levels of aggregation, hyperphosphorylation, defects in mRNA splicing, and weakened interaction with microtubules. Given the differential effects of the mutations, it may not be surprising that the pathology associated with FTDP-17 can vary widely as well. Despite this variety, several of the mutations are commonly used interchangeably as aggregation inducers for in vitro and in vivo models of tauopathies. We generated recombinant forms of 12 FTDP-17 mutations chosen for their predicted effects on the charge, hydrophobicity, and secondary structure of the protein. We then examined the effects that the mutations had on the properties of in vitro aggregation of the protein and its ability to stabilize microtubule assembly. The group of mutations induced very different effects on the total amount of aggregation, the kinetics of aggregation, and filament morphology. Several of the mutations inhibited the microtubule stabilization ability of tau, while others had very little effect compared to wild-type tau. These results indicate that the mechanisms of disease progression may differ among FTDP-17 mutations and that the effects of the varying mutations may not be equal in all model systems.
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Affiliation(s)
- Benjamin Combs
- Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045, USA
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Nübling G, Bader B, Levin J, Hildebrandt J, Kretzschmar H, Giese A. Synergistic influence of phosphorylation and metal ions on tau oligomer formation and coaggregation with α-synuclein at the single molecule level. Mol Neurodegener 2012; 7:35. [PMID: 22824345 PMCID: PMC3472288 DOI: 10.1186/1750-1326-7-35] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 06/30/2012] [Indexed: 01/05/2023] Open
Abstract
Background Fibrillar amyloid-like deposits and co-deposits of tau and α-synuclein are found in several common neurodegenerative diseases. Recent evidence indicates that small oligomers are the most relevant toxic aggregate species. While tau fibril formation is well-characterized, factors influencing tau oligomerization and molecular interactions of tau and α-synuclein are not well understood. Results We used a novel approach applying confocal single-particle fluorescence to investigate the influence of tau phosphorylation and metal ions on tau oligomer formation and its coaggregation with α-synuclein at the level of individual oligomers. We show that Al3+ at physiologically relevant concentrations and tau phosphorylation by GSK-3β exert synergistic effects on the formation of a distinct SDS-resistant tau oligomer species even at nanomolar protein concentration. Moreover, tau phosphorylation and Al3+ as well as Fe3+ enhanced both formation of mixed oligomers and recruitment of α-synuclein in pre-formed tau oligomers. Conclusions Our findings provide a new perspective on interactions of tau phosphorylation, metal ions, and the formation of potentially toxic oligomer species, and elucidate molecular crosstalks between different aggregation pathways involved in neurodegeneration.
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Affiliation(s)
- Georg Nübling
- Center for Neuropathology and Prion Research, Ludwig-Maximilians-Universität, Feodor-Lynen-Str, 23, 81377, Munich, Germany
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Voss K, Combs B, Patterson KR, Binder LI, Gamblin TC. Hsp70 alters tau function and aggregation in an isoform specific manner. Biochemistry 2012; 51:888-98. [PMID: 22236337 DOI: 10.1021/bi2018078] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Tauopathies are characterized by abnormal aggregation of the microtubule associated protein tau. This aggregation is thought to occur when tau undergoes shifts from its native conformation to one that exposes hydrophobic areas on separate monomers, allowing contact and subsequent association into oligomers and filaments. Molecular chaperones normally function by binding to exposed hydrophobic stretches on proteins and assisting in their refolding. Chaperones of the heat shock protein 70 (Hsp70) family have been implicated in the prevention of abnormal tau aggregation in adult neurons. Tau exists as six alternatively spliced isoforms, and all six isoforms appear capable of forming the pathological aggregates seen in Alzheimer's disease. Because tau isoforms differ in primary sequence, we sought to determine whether Hsp70 would differentially affect the aggregation and microtubule assembly characteristics of the various tau isoforms. We found that Hsp70 inhibits tau aggregation directly and not through inducer-mediated effects. We also determined that Hsp70 inhibits the aggregation of each individual tau isoform and was more effective at inhibiting the three repeat isoforms. Finally, all tau isoforms robustly induced microtubule formation while in the presence of Hsp70. The results presented herein indicate that Hsp70 affects tau isoform dysfunction while having very little impact on the normal function of tau to mediate microtubule assembly. This indicates that targeting Hsp70 to tau may provide a therapeutic approach for the treatment of tauopathies that avoids disruption of normal tau function.
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Affiliation(s)
- Kellen Voss
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, United States
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Abstract
Tauopathies are age-related neurodegenerative diseases that are characterized by the presence of aggregates of abnormally phosphorylated tau. As tau was originally discovered as a microtubule-associated protein, it has been hypothesized that neurodegeneration results from a loss of the ability of tau to associate with microtubules. However, tau has been found to have other functions aside from the promotion and stabilization of microtubule assembly. It is conceivable that such functions may be affected by the abnormal phosphorylation of tau and might have consequences for neuronal function or viability. This chapter provides an overview of tau structure, functions, and its involvement in neurodegenerative diseases.
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Moore CL, Huang MH, Robbennolt SA, Voss KR, Combs B, Gamblin TC, Goux WJ. Secondary nucleating sequences affect kinetics and thermodynamics of tau aggregation. Biochemistry 2011; 50:10876-86. [PMID: 22085312 DOI: 10.1021/bi2014745] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tau protein was scanned for highly amyloidogenic sequences in amphiphilic motifs (X)(n)Z, Z(X)(n)Z (n ≥ 2), or (XZ)(n) (n ≥ 2), where X is a hydrophobic residue and Z is a charged or polar residue. N-Acetyl peptides homologous to these sequences were used to study aggregation. Transmission electron microscopy (TEM) showed seven peptides, in addition to well-known primary nucleating sequences Ac(275)VQIINK (AcPHF6*) and Ac(306)VQIVYK (AcPHF6), formed fibers, tubes, ribbons, or rolled sheets. Of the peptides shown by TEM to form amyloid, Ac(10)VME, AcPHF6*, Ac(375)KLTFR, and Ac(393)VYK were found to enhance the fraction of β-structure of AcPHF6 formed at equilibrium, and Ac(375)KLTFR was found to inhibit AcPHF6 and AcPHF6* aggregation kinetics in a dose-dependent manner, consistent with its participation in a hybrid steric zipper model. Single site mutants were generated which transformed predicted amyloidogenic sequences in tau into non-amyloidogenic ones. A M11K mutant had fewer filaments and showed a decrease in aggregation kinetics and an increased lag time compared to wild-type tau, while a F378K mutant showed significantly more filaments. Our results infer that sequences throughout tau, in addition to PHF6 and PHF6*, can seed amyloid formation or affect aggregation kinetics or thermodynamics.
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Affiliation(s)
- Christopher L Moore
- Department of Chemistry, The University of Texas at Dallas, Richardson, Texas 75080, United States
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Combs B, Voss K, Gamblin TC. Pseudohyperphosphorylation has differential effects on polymerization and function of tau isoforms. Biochemistry 2011; 50:9446-56. [PMID: 21942206 DOI: 10.1021/bi2010569] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The microtubule-associated protein tau exists as six isoforms created through the splicing of the second, third, and tenth exons. The isoforms are classified by their number of N-terminal exons (0N, 1N, or 2N) and by their number of microtubule-binding repeat regions (3R or 4R). Hyperphosphorylated isoforms accumulate in insoluble aggregates in Alzheimer's disease and other tauopathies. These neurodegenerative diseases can be categorized based on the isoform content of the aggregates they contain. Hyperphosphorylated tau has the general characteristics of an upward electrophoretic shift, decreased microtubule binding, and an association with aggregation. Previously we have shown that a combination of seven pseudophosphorylation mutations at sites phosphorylated by GSK-3β, referred to as 7-Phos, induced several of these characteristics in full-length 2N4R tau and led to the formation of fewer but longer filaments. We sought to determine whether the same phosphorylation pattern could cause differential effects in the other tau isoforms, possibly through varied conformational effects. Using in vitro techniques, we examined the electrophoretic mobility, aggregation properties, and microtubule stabilization of all isoforms and their pseudophosphorylated counterparts. We found that pseudophosphorylation affected each isoform, but in several cases certain isoforms were affected more than others. These results suggest that hyperphosphorylation of tau isoforms could play a major role in determining the isoform composition of tau aggregates in disease.
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Affiliation(s)
- Benjamin Combs
- Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, United States
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García-Sierra F, Jarero-Basulto JJ, Kristofikova Z, Majer E, Binder LI, Ripova D. Ubiquitin is associated with early truncation of tau protein at aspartic acid(421) during the maturation of neurofibrillary tangles in Alzheimer's disease. Brain Pathol 2011; 22:240-50. [PMID: 21919991 DOI: 10.1111/j.1750-3639.2011.00525.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Pathological processing of tau protein during the formation and maturation of neurofibrillary tangles (NFTs) includes abnormal phosphorylation, conformational changes and truncation of the C-terminus at aspartic-acid(421) (apoptotic product) and glutamic-acid(391) residues. Abnormal phosphorylation and misfolding may serve as recognition signals for ubiquitin-targeting and proteosomal processing. For this reason, we sought to determine whether ubiquitin-targeting of tau is associated with particular tau modifications that herald specific stages of NFTs maturation in the hippocampus of Alzheimer's disease cases. Using multiple tau antibodies, we found that 30% of the total load of NFTs is ubiquitin-associated. As reported previously ubiquitin immunoreactivity was associated with markers of phosphorylated tau in certain NFTs; however, a strong association was also found between ubiquitin and the earliest known truncation event at aspartic-acid(421) . These findings indicate that tau protein in the NFTs may be dually subjected to both apoptotic and proteosomal processing. By contrast ubiquitin immunoreactivity was poorly associated with truncation of tau at glutamic-acid(391) , suggesting that this proteolytic event may be independent of proteosomal activity. It would appear, therefore, that ubiquitin targeting of tau protein occurs at NFTs in the early and intermediate stages of the maturation.
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Affiliation(s)
- Francisco García-Sierra
- Department of Cell Biology, Center of Research and Advanced Studies of the National Polytechnic Institute, Mexico City, Mexico.
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Bibow S, Ozenne V, Biernat J, Blackledge M, Mandelkow E, Zweckstetter M. Structural Impact of Proline-Directed Pseudophosphorylation at AT8, AT100, and PHF1 Epitopes on 441-Residue Tau. J Am Chem Soc 2011; 133:15842-5. [DOI: 10.1021/ja205836j] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Stefan Bibow
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Valéry Ozenne
- Institut de Biologie Structurale Jean-Pierre Ebel, CEA-CNRS-UJF UMR 5075, 41 Rue Jules Horowitz, Grenoble 38027, France
| | - Jacek Biernat
- Max Planck Unit for Structural Molecular Biology, c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
- DZNE, German Center for Neurodegenerative Diseases, c/o CAESAR, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Martin Blackledge
- Institut de Biologie Structurale Jean-Pierre Ebel, CEA-CNRS-UJF UMR 5075, 41 Rue Jules Horowitz, Grenoble 38027, France
| | - Eckhard Mandelkow
- Max Planck Unit for Structural Molecular Biology, c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
- DZNE, German Center for Neurodegenerative Diseases, c/o CAESAR, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Markus Zweckstetter
- Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
- DFG Center for the Molecular Physiology of the Brain, 37073 Göttingen, Germany
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Induction of intracellular tau aggregation is promoted by α-synuclein seeds and provides novel insights into the hyperphosphorylation of tau. J Neurosci 2011; 31:7604-18. [PMID: 21613474 DOI: 10.1523/jneurosci.0297-11.2011] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Intracytoplasmic proteinaceous inclusions, primarily composed of tau or α-synuclein (α-syn), are predominant pathological features of Alzheimer's disease (AD) and Parkinson's disease (PD), respectively. However, the coexistence of these pathological aggregates is identified in many neurodegenerative disorders, including spectrum disorders of AD and PD. Whereas α-syn can spontaneously polymerize into amyloidogenic fibrils, in vitro, tau polymerization requires an inducing agent. The current study presents a human-derived cellular model, in which recombinant, preformed α-syn fibrils cross-seed intracellular tau to promote the formation of neurofibrillary tangle-like aggregates. These aggregates were hyperphosphorylated, Triton insoluble, and thioflavin-S positive, either comingling with endogenously expressed α-syn aggregates or induced by only exogenously applied recombinant α-syn fibrils. Furthermore, filamentous, amyloidogenic tau took over the cellular soma, displacing the nucleus and isolating or displacing organelles, likely preventing cellular function. Although a significant proportion of wild-type tau formed these cellular inclusions, the P301L mutation in tau increased aggregation propensity resulting from α-syn seeds to over 50% of total tau protein. The role of phosphorylation on the development of these tau aggregates was investigated by coexpressing glycogen synthase kinase 3 β or microtubule-associated protein/microtubule affinity-regulating kinase 2. Expression of either kinase inhibited the formation of α-syn-induced tau aggregates. Analyses of phosphorylation sites suggest that multiple complex factors may be associated with this effect and that Triton-soluble versus Triton-insoluble tau may be independently targeted by kinases. The current work not only provides an exceptional cellular model of tau pathology, but also examines α-syn-induced tau inclusion formation and provides novel insights into hyperphosphorylation observed in disease.
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Kanaan NM, Morfini G, Pigino G, LaPointe NE, Andreadis A, Song Y, Leitman E, Binder LI, Brady ST. Phosphorylation in the amino terminus of tau prevents inhibition of anterograde axonal transport. Neurobiol Aging 2011; 33:826.e15-30. [PMID: 21794954 DOI: 10.1016/j.neurobiolaging.2011.06.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2011] [Revised: 05/19/2011] [Accepted: 06/06/2011] [Indexed: 01/01/2023]
Abstract
Alzheimer's disease (AD) and other tauopathies are characterized by fibrillar inclusions composed of the microtubule-associated protein, tau. Recently, we demonstrated that the N-terminus of tau (amino acids [aa] 2-18) in filamentous aggregates or N-terminal tau isoforms activate a signaling cascade involving protein phosphatase 1 and glycogen synthase kinase 3 that results in inhibition of anterograde fast axonal transport (FAT). We have termed the functional motif comprised of aa 2-18 in tau the phosphatase-activating domain (PAD). Here, we show that phosphorylation of tau at tyrosine 18, which is a fyn phosphorylation site within PAD, prevents inhibition of anterograde FAT induced by both filamentous tau and 6D tau. Moreover, Fyn-mediated phosphorylation of tyrosine 18 is reduced in disease-associated forms of tau (e.g., tau filaments). A novel PAD-specific monoclonal antibody revealed that exposure of PAD in tau occurs before and more frequently than tyrosine 18 phosphorylation in the evolution of tangle formation in AD. These results indicate that N-terminal phosphorylation may constitute a regulatory mechanism that controls tau-mediated inhibition of anterograde FAT in AD.
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Affiliation(s)
- Nicholas M Kanaan
- Division of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI, USA
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33
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De Vos A, Anandhakumar J, Van den Brande J, Verduyckt M, Franssens V, Winderickx J, Swinnen E. Yeast as a model system to study tau biology. Int J Alzheimers Dis 2011; 2011:428970. [PMID: 21559193 PMCID: PMC3090044 DOI: 10.4061/2011/428970] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 01/21/2011] [Indexed: 11/20/2022] Open
Abstract
Hyperphosphorylated and aggregated human protein tau constitutes a hallmark of a multitude of neurodegenerative diseases called tauopathies, exemplified by Alzheimer's disease. In spite of an enormous amount of research performed on tau biology, several crucial questions concerning the mechanisms of tau toxicity remain unanswered. In this paper we will highlight some of the processes involved in tau biology and pathology, focusing on tau phosphorylation and the interplay with oxidative stress. In addition, we will introduce the development of a human tau-expressing yeast model, and discuss some crucial results obtained in this model, highlighting its potential in the elucidation of cellular processes leading to tau toxicity.
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Affiliation(s)
- Ann De Vos
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Jayamani Anandhakumar
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Jeff Van den Brande
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Mathias Verduyckt
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Vanessa Franssens
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Joris Winderickx
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Erwin Swinnen
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
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34
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Lisa S, Meli M, Cabello G, Gabizon R, Colombo G, Gasset M. The structural intolerance of the PrP alpha-fold for polar substitution of the helix-3 methionines. Cell Mol Life Sci 2010; 67:2825-38. [PMID: 20454997 PMCID: PMC11115822 DOI: 10.1007/s00018-010-0363-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 03/17/2010] [Accepted: 03/19/2010] [Indexed: 12/29/2022]
Abstract
The conversion of the cellular prion protein (PrP(C)) into its disease-associated form (PrP(Sc)) involves a major conformational change and the accumulation of sulfoxidized methionines. Computational and synthetic approaches have shown that this change in the polarity of M206 and M213 impacts the C-terminal domain native alpha-fold allowing the flexibility required for the structural conversion. To test the effect in the full-length molecule with site-specificity, we have generated M-to-S mutations. Molecular dynamics simulations show that the replacement indeed perturbs the native state. When this mutation is placed at the conserved methionines of HaPrP(23-231), only substitutions at the Helix-3 impair the alpha-fold, stabilizing a non-native state with perturbed secondary structure, loss of native tertiary contacts, increased surface hydrophobicity, reduced thermal stability and an enhanced tendency to aggregate into protofibrillar polymers. Our work supports that M206 and M213 function as alpha-fold gatekeepers and suggests that their redox state regulate misfolding routes.
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Affiliation(s)
- Silvia Lisa
- Insto Química-Física “Rocasolano”, CSIC, Serrano 119, 28006 Madrid, Spain
| | - Massimiliano Meli
- Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Via Mario Bianco 9, 20131 Milan, Italy
| | - Gema Cabello
- Insto Química-Física “Rocasolano”, CSIC, Serrano 119, 28006 Madrid, Spain
| | - Ruth Gabizon
- Department of Neurology, The Agnes Ginges Center for Human Neurogenetics, Hadassah University Hospital, 91120 Jerusalem, Israel
| | - Giorgio Colombo
- Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Via Mario Bianco 9, 20131 Milan, Italy
| | - María Gasset
- Insto Química-Física “Rocasolano”, CSIC, Serrano 119, 28006 Madrid, Spain
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35
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Hanger DP, Seereeram A, Noble W. Mediators of tau phosphorylation in the pathogenesis of Alzheimer's disease. Expert Rev Neurother 2010; 9:1647-66. [PMID: 19903024 DOI: 10.1586/ern.09.104] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The need for disease-modifying drugs for Alzheimer's disease has become increasingly important owing to escalating disease prevalence and the associated socio-economic burden. Until recently, reducing brain amyloid accumulation has been the main therapeutic focus; however, increasing evidence suggests that targeting abnormal tau phosphorylation could be beneficial. Tau is phosphorylated by several protein kinases and this is balanced by dephosphorylation by protein phosphatases. Phosphorylation at specific sites can influence the physiological functions of tau, including its role in binding to and stabilizing the neuronal cytoskeleton. aberrant phosphorylation of tau could render it susceptible to potentially pathogenic alterations, including conformational changes, proteolytic cleavage and aggregation. While strategies that reduce tau phosphorylation in transgenic models of disease have been promising, our understanding of the mechanisms through which tau becomes abnormally phosphorylated in disease is lacking.
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Affiliation(s)
- Diane P Hanger
- MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry, Department of Neuroscience (P037), De Crespigny Park, London SE5 8AF, UK.
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