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Tau Is Truncated in Five Regions of the Normal Adult Human Brain. Int J Mol Sci 2021; 22:ijms22073521. [PMID: 33805376 PMCID: PMC8036332 DOI: 10.3390/ijms22073521] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 03/24/2021] [Accepted: 03/25/2021] [Indexed: 01/01/2023] Open
Abstract
The truncation of Tau is thought to be important in promoting aggregation, with this feature characterising the pathology of dementias such as Alzheimer disease. Antibodies to the C-terminal and N-terminal regions of Tau were employed to examine Tau cleavage in five human brain regions: the entorhinal cortex, prefrontal cortex, motor cortex, hippocampus, and cerebellum. These were obtained from normal subjects ranging in age from 18 to 104 years. Tau fragments of approximately 40 kDa and 45 kDa with an intact N-terminus retained were found in soluble and insoluble brain fractions. In addition, smaller C-terminal Tau fragments ranging in mass from 17 kDa to 25 kDa were also detected. These findings are consistent with significant Tau cleavage taking place in brain regions from 18 years onwards. It appears that site-specific cleavage of Tau is widespread in the normal human brain, and that large Tau fragments that contain the N-terminus, as well as shorter C-terminal Tau fragments, are present in brain cells across the age range.
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2
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Oakley SS, Maina MB, Marshall KE, Al-Hilaly YK, Harrington CR, Wischik CM, Serpell LC. Tau Filament Self-Assembly and Structure: Tau as a Therapeutic Target. Front Neurol 2020; 11:590754. [PMID: 33281730 PMCID: PMC7688747 DOI: 10.3389/fneur.2020.590754] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 09/04/2020] [Indexed: 12/12/2022] Open
Abstract
Tau plays an important pathological role in a group of neurodegenerative diseases called tauopathies, including Alzheimer's disease, Pick's disease, chronic traumatic encephalopathy and corticobasal degeneration. In each disease, tau self-assembles abnormally to form filaments that deposit in the brain. Tau is a natively unfolded protein that can adopt distinct structures in different pathological disorders. Cryo-electron microscopy has recently provided a series of structures for the core of the filaments purified from brain tissue from patients with different tauopathies and revealed that they share a common core region, while differing in their specific conformation. This structurally resolvable part of the core is contained within a proteolytically stable core region from the repeat domain initially isolated from AD tau filaments. Tau has recently become an important target for therapy. Recent work has suggested that the prevention of tau self-assembly may be effective in slowing the progression of Alzheimer's disease and other tauopathies. Here we review the work that explores the importance of tau filament structures and tau self-assembly mechanisms, as well as examining model systems that permit the exploration of the mode of action of potential inhibitors.
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Affiliation(s)
- Sebastian S Oakley
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Mahmoud B Maina
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom.,College of Medical Sciences, Yobe State University, Damaturu, Nigeria
| | - Karen E Marshall
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Youssra K Al-Hilaly
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom.,Chemistry Department, College of Science, Mustansiriyah University, Baghdad, Iraq
| | - Charlie R Harrington
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, United Kingdom.,TauRx Therapeutics Ltd., Aberdeen, United Kingdom
| | - Claude M Wischik
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, United Kingdom.,TauRx Therapeutics Ltd., Aberdeen, United Kingdom
| | - Louise C Serpell
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
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3
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Guo T, Zhang D, Zeng Y, Huang TY, Xu H, Zhao Y. Molecular and cellular mechanisms underlying the pathogenesis of Alzheimer's disease. Mol Neurodegener 2020; 15:40. [PMID: 32677986 PMCID: PMC7364557 DOI: 10.1186/s13024-020-00391-7] [Citation(s) in RCA: 233] [Impact Index Per Article: 58.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 06/17/2020] [Indexed: 12/11/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common neurodegenerative disorder seen in age-dependent dementia. There is currently no effective treatment for AD, which may be attributed in part to lack of a clear underlying mechanism. Studies within the last few decades provide growing evidence for a central role of amyloid β (Aβ) and tau, as well as glial contributions to various molecular and cellular pathways in AD pathogenesis. Herein, we review recent progress with respect to Aβ- and tau-associated mechanisms, and discuss glial dysfunction in AD with emphasis on neuronal and glial receptors that mediate Aβ-induced toxicity. We also discuss other critical factors that may affect AD pathogenesis, including genetics, aging, variables related to environment, lifestyle habits, and describe the potential role of apolipoprotein E (APOE), viral and bacterial infection, sleep, and microbiota. Although we have gained much towards understanding various aspects underlying this devastating neurodegenerative disorder, greater commitment towards research in molecular mechanism, diagnostics and treatment will be needed in future AD research.
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Affiliation(s)
- Tiantian Guo
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Denghong Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China
| | - Yuzhe Zeng
- Department of Orthopaedics, Orthopaedic Center of People's Liberation Army, The Affiliated Southeast Hospital of Xiamen University, Zhangzhou, China
| | - Timothy Y Huang
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA.
| | - Huaxi Xu
- Neuroscience Initiative, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA.
| | - Yingjun Zhao
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen, China.
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4
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Ibarra-Bracamontes VJ, Escobar-Herrera J, Kristofikova Z, Rípova D, Florán-Garduño B, Garcia-Sierra F. Early but not late conformational changes of tau in association with ubiquitination of neurofibrillary pathology in Alzheimer's disease brains. Brain Res 2020; 1744:146953. [PMID: 32526294 DOI: 10.1016/j.brainres.2020.146953] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 06/03/2020] [Accepted: 06/06/2020] [Indexed: 10/24/2022]
Abstract
In Alzheimer's disease, tau protein undergoes post-translational modifications including hyperphosphorylation and truncation, which promotes two major conformational changes associated with progressive N-terminal folding. Along with the development of the disease, tau ubiquitination was previously shown to emerge in the early and intermediate stages of the disease, which is closely associated with early tau truncation at aspartic acid 421, but not with a subsequently truncated tau molecule at glutamic acid 391. In the same group of cases, using multiple immunolabeling and confocal microscopy, a possible relationship between the ubiquitin-targeting of tau and the progression of conformational changes adopted by the N-terminus of this molecule was further studied. A comparable number of neurofibrillary tangles was found displaying ubiquitin, an early conformation recognized by the Alz-50 antibody, and a phosphorylation. However, a more reduced number of neurofibrillary tangles were immunoreactive to Tau-66 antibody, a late tau conformational change marker. When double-labeling profiles of neurofibrillary tangles were assessed, ubiquitination was clearly demonstrated in tau molecules undergoing early N-terminal folding, but was barely observed in late conformational changes of the N-terminus adopted by tau. The same pattern of colocalization was visualized in neuritic pathology. Overall, these results indicate that a more intact conformation of the N-terminus of tau may facilitate tau ubiquitination, but this modification may not occur in a late truncated and more compressed folding of the N-terminus of the tau molecule.
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Affiliation(s)
- Vanessa J Ibarra-Bracamontes
- Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies of the National Polytechnic Institute, Mexico City, Mexico
| | - Jaime Escobar-Herrera
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute, Mexico City, Mexico
| | | | - Daniela Rípova
- National Institute of Mental Health, Klecany, Czech Republic
| | - Benjamín Florán-Garduño
- Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies of the National Polytechnic Institute, Mexico City, Mexico
| | - Francisco Garcia-Sierra
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute, Mexico City, Mexico.
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5
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Tapia-Rojas C, Cabezas-Opazo F, Deaton CA, Vergara EH, Johnson GVW, Quintanilla RA. It's all about tau. Prog Neurobiol 2018; 175:54-76. [PMID: 30605723 DOI: 10.1016/j.pneurobio.2018.12.005] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 12/07/2018] [Accepted: 12/28/2018] [Indexed: 12/21/2022]
Abstract
Tau is a protein that is highly enriched in neurons and was originally defined by its ability to bind and stabilize microtubules. However, it is now becoming evident that the functions of tau extend beyond its ability to modulate microtubule dynamics. Tau plays a role in mediating axonal transport, synaptic structure and function, and neuronal signaling pathways. Although tau plays important physiological roles in neurons, its involvement in neurodegenerative diseases, and most prominently in the pathogenesis of Alzheimer disease (AD), has directed the majority of tau studies. However, a thorough knowledge of the physiological functions of tau and its post-translational modifications under normal conditions are necessary to provide the foundation for understanding its role in pathological settings. In this review, we will focus on human tau, summarizing tau structure and organization, as well as its posttranslational modifications associated with physiological processes. We will highlight possible mechanisms involved in mediating the turnover of tau and finally discuss newly elucidated tau functions in a physiological context.
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Affiliation(s)
- Cheril Tapia-Rojas
- Laboratory of Neurobiology of Aging, Centro de Biología Celular y Biomedicina (CEBICEM), Universidad San Sebastián, Santiago, Chile
| | - Fabian Cabezas-Opazo
- Laboratory of Neurodegenerative Diseases, Centro de Investigación Biomédica, Universidad Autónoma de Chile, Santiago, Chile
| | - Carol A Deaton
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, NY, USA
| | - Erick H Vergara
- Laboratory of Neurodegenerative Diseases, Centro de Investigación Biomédica, Universidad Autónoma de Chile, Santiago, Chile
| | - Gail V W Johnson
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, NY, USA
| | - Rodrigo A Quintanilla
- Laboratory of Neurodegenerative Diseases, Centro de Investigación Biomédica, Universidad Autónoma de Chile, Santiago, Chile; Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes (CIIA), Santiago, Chile.
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6
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Chen HH, Liu P, Auger P, Lee SH, Adolfsson O, Rey-Bellet L, Lafrance-Vanasse J, Friedman BA, Pihlgren M, Muhs A, Pfeifer A, Ernst J, Ayalon G, Wildsmith KR, Beach TG, van der Brug MP. Calpain-mediated tau fragmentation is altered in Alzheimer's disease progression. Sci Rep 2018; 8:16725. [PMID: 30425303 PMCID: PMC6233188 DOI: 10.1038/s41598-018-35130-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 10/30/2018] [Indexed: 11/09/2022] Open
Abstract
The aggregation of intracellular tau protein is a major hallmark of Alzheimer's disease (AD). The extent and the stereotypical spread of tau pathology in the AD brain are correlated with cognitive decline during disease progression. Here we present an in-depth analysis of endogenous tau fragmentation in a well-characterized cohort of AD and age-matched control subjects. Using protein mass spectrometry and Edman degradation to interrogate endogenous tau fragments in the human brain, we identified two novel proteolytic sites, G323 and G326, as major tau cleavage events in both normal and AD cortex. These sites are located within the sequence recently identified as the structural core of tau protofilaments, suggesting an inhibitory mechanism of fibril formation. In contrast, a different set of novel cleavages showed a distinct increase in late stage AD. These disease-associated sites are located outside of the protofilament core sequence. We demonstrate that calpain 1 specifically cleaves at both the normal and diseased sites in vitro, and the site selection is conformation-dependent. Monomeric tau is predominantly cleaved at G323/G326 (normal sites), whereas oligomerization increases cleavages at the late-AD-associated sites. The fragmentation patterns specific to disease and healthy states suggest novel regulatory mechanisms of tau aggregation in the human brain.
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Affiliation(s)
- Hsu-Hsin Chen
- Biomarker Discovery, Genentech, Inc., 1 DNA Way, South San Francisco, CA, USA.
| | - Peter Liu
- Microchemistry, Proteomics and Lipidomics, Genentech, Inc., 1 DNA Way, South San Francisco, CA, USA
| | - Paul Auger
- Biomarker Development, Genentech, Inc., 1 DNA Way, South San Francisco, CA, USA
| | - Seung-Hye Lee
- Neuroscience, Genentech, Inc., 1 DNA Way, South San Francisco, CA, USA
| | - Oskar Adolfsson
- AC Immune SA, EPFL Innovation Park, Building B, CH-1015, Lausanne, Switzerland
| | - Lorianne Rey-Bellet
- AC Immune SA, EPFL Innovation Park, Building B, CH-1015, Lausanne, Switzerland
| | | | - Brad A Friedman
- Neuroscience, Genentech, Inc., 1 DNA Way, South San Francisco, CA, USA
| | - Maria Pihlgren
- AC Immune SA, EPFL Innovation Park, Building B, CH-1015, Lausanne, Switzerland
| | - Andreas Muhs
- AC Immune SA, EPFL Innovation Park, Building B, CH-1015, Lausanne, Switzerland
| | - Andrea Pfeifer
- AC Immune SA, EPFL Innovation Park, Building B, CH-1015, Lausanne, Switzerland
| | - James Ernst
- Protein Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA, USA
| | - Gai Ayalon
- Neuroscience, Genentech, Inc., 1 DNA Way, South San Francisco, CA, USA
| | - Kristin R Wildsmith
- Biomarker Development, Genentech, Inc., 1 DNA Way, South San Francisco, CA, USA
| | - Thomas G Beach
- Banner Sun Health Research Institute, 10515W, Santa Fe Drive, Sun City, AZ, USA
| | - Marcel P van der Brug
- Biomarker Discovery, Genentech, Inc., 1 DNA Way, South San Francisco, CA, USA.,Therapeutics Division, Clover Health, 22 4th Street, San Francisco, CA, USA
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7
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Stem Cells as Potential Targets of Polyphenols in Multiple Sclerosis and Alzheimer's Disease. BIOMED RESEARCH INTERNATIONAL 2018; 2018:1483791. [PMID: 30112360 PMCID: PMC6077677 DOI: 10.1155/2018/1483791] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 06/19/2018] [Indexed: 12/16/2022]
Abstract
Alzheimer's disease (AD) and multiple sclerosis are major neurodegenerative diseases, which are characterized by the accumulation of abnormal pathogenic proteins due to oxidative stress, mitochondrial dysfunction, impaired autophagy, and pathogens, leading to neurodegeneration and behavioral deficits. Herein, we reviewed the utility of plant polyphenols in regulating proliferation and differentiation of stem cells for inducing brain self-repair in AD and multiple sclerosis. Firstly, we discussed the genetic, physiological, and environmental factors involved in the pathophysiology of both the disorders. Next, we reviewed various stem cell therapies available and how they have proved useful in animal models of AD and multiple sclerosis. Lastly, we discussed how polyphenols utilize the potential of stem cells, either complementing their therapeutic effects or stimulating endogenous and exogenous neurogenesis, against these diseases. We suggest that polyphenols could be a potential candidate for stem cell therapy against neurodegenerative disorders.
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8
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Zhou Y, Shi J, Chu D, Hu W, Guan Z, Gong CX, Iqbal K, Liu F. Relevance of Phosphorylation and Truncation of Tau to the Etiopathogenesis of Alzheimer's Disease. Front Aging Neurosci 2018; 10:27. [PMID: 29472853 PMCID: PMC5810298 DOI: 10.3389/fnagi.2018.00027] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 01/22/2018] [Indexed: 01/29/2023] Open
Abstract
Microtubule (MT) associated protein tau is abnormally hyperphosphorylated and aggregated into paired helical filaments (PHFs), which manifest as neurofibrillary tangles (NFTs) in the brains of individuals with Alzheimer’s disease (AD) and related tauopathies. Hyperphosphorylation and truncation of tau have been linked to the progression of the disease. However, the nature of phosphorylation and truncation of tau in AD brain are not very clear. In the present study we investigated the association of phosphorylation and truncation with high-molecular weight oligomers of tau (HMW-tau) in post-mortem AD brain by western blots. We found that tau from AD brain appears as a smear from low molecular weight (LMW) to HMW tau species in western blots developed with pan-tau antibodies. Similar level of LMW-tau was found in AD and control brains, whereas HMW-tau was found in AD brain only. HMW-tau was hyperphosphorylated at multiple sites and not unphosphorylated at Ser46 or Ser198/199/202. HMW-tau was weakly labeled by tau antibodies 43D against a.a. 6–18 and HT7 against a.a. 159–163 of tau, whereas, the C-terminal antibodies, tau46 and tau46.1, strongly labeled HMW-tau. The ratio of HMW-tau/LMW-tau detected by tau antibodies increased as the epitope of the tau antibodies ranges from N-terminal to C-terminal. The level of tau truncated at Asp421 was increased in AD brain, but was poorly associated with the HMW-tau. These findings suggest that tau pathogenesis involves both hyperphosphorylation and dominantly N-terminal truncation of tau in AD.
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Affiliation(s)
- Yan Zhou
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, New York, NY, United States.,Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, China
| | - Jianhua Shi
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, New York, NY, United States
| | - Dandan Chu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Wen Hu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, New York, NY, United States
| | - Zongyu Guan
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Cheng-Xin Gong
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, New York, NY, United States
| | - Khalid Iqbal
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, New York, NY, United States
| | - Fei Liu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education of China, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China.,Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, New York, NY, United States
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9
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Kulbe JR, Hall ED. Chronic traumatic encephalopathy-integration of canonical traumatic brain injury secondary injury mechanisms with tau pathology. Prog Neurobiol 2017; 158:15-44. [PMID: 28851546 PMCID: PMC5671903 DOI: 10.1016/j.pneurobio.2017.08.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 08/09/2017] [Accepted: 08/17/2017] [Indexed: 12/14/2022]
Abstract
In recent years, a new neurodegenerative tauopathy labeled Chronic Traumatic Encephalopathy (CTE), has been identified that is believed to be primarily a sequela of repeated mild traumatic brain injury (TBI), often referred to as concussion, that occurs in athletes participating in contact sports (e.g. boxing, American football, Australian football, rugby, soccer, ice hockey) or in military combatants, especially after blast-induced injuries. Since the identification of CTE, and its neuropathological finding of deposits of hyperphosphorylated tau protein, mechanistic attention has been on lumping the disorder together with various other non-traumatic neurodegenerative tauopathies. Indeed, brains from suspected CTE cases that have come to autopsy have been confirmed to have deposits of hyperphosphorylated tau in locations that make its anatomical distribution distinct for other tauopathies. The fact that these individuals experienced repetitive TBI episodes during their athletic or military careers suggests that the secondary injury mechanisms that have been extensively characterized in acute TBI preclinical models, and in TBI patients, including glutamate excitotoxicity, intracellular calcium overload, mitochondrial dysfunction, free radical-induced oxidative damage and neuroinflammation, may contribute to the brain damage associated with CTE. Thus, the current review begins with an in depth analysis of what is known about the tau protein and its functions and dysfunctions followed by a discussion of the major TBI secondary injury mechanisms, and how the latter have been shown to contribute to tau pathology. The value of this review is that it might lead to improved neuroprotective strategies for either prophylactically attenuating the development of CTE or slowing its progression.
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Affiliation(s)
- Jacqueline R Kulbe
- Spinal Cord & Brain Injury Research Center, University of Kentucky College of Medicine, United States; Department of Neuroscience, University of Kentucky College of Medicine, United States
| | - Edward D Hall
- Spinal Cord & Brain Injury Research Center, University of Kentucky College of Medicine, United States; Department of Neuroscience, University of Kentucky College of Medicine, United States.
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10
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Guo T, Noble W, Hanger DP. Roles of tau protein in health and disease. Acta Neuropathol 2017; 133:665-704. [PMID: 28386764 PMCID: PMC5390006 DOI: 10.1007/s00401-017-1707-9] [Citation(s) in RCA: 546] [Impact Index Per Article: 78.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 03/26/2017] [Accepted: 03/26/2017] [Indexed: 01/18/2023]
Abstract
Tau is well established as a microtubule-associated protein in neurons. However, under pathological conditions, aberrant assembly of tau into insoluble aggregates is accompanied by synaptic dysfunction and neural cell death in a range of neurodegenerative disorders, collectively referred to as tauopathies. Recent advances in our understanding of the multiple functions and different locations of tau inside and outside neurons have revealed novel insights into its importance in a diverse range of molecular pathways including cell signalling, synaptic plasticity, and regulation of genomic stability. The present review describes the physiological and pathophysiological properties of tau and how these relate to its distribution and functions in neurons. We highlight the post-translational modifications of tau, which are pivotal in defining and modulating tau localisation and its roles in health and disease. We include discussion of other pathologically relevant changes in tau, including mutation and aggregation, and how these aspects impinge on the propensity of tau to propagate, and potentially drive neuronal loss, in diseased brain. Finally, we describe the cascade of pathological events that may be driven by tau dysfunction, including impaired axonal transport, alterations in synapse and mitochondrial function, activation of the unfolded protein response and defective protein degradation. It is important to fully understand the range of neuronal functions attributed to tau, since this will provide vital information on its involvement in the development and pathogenesis of disease. Such knowledge will enable determination of which critical molecular pathways should be targeted by potential therapeutic agents developed for the treatment of tauopathies.
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Affiliation(s)
- Tong Guo
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE5 9NU, UK
| | - Wendy Noble
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE5 9NU, UK
| | - Diane P Hanger
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE5 9NU, UK.
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11
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Zhang Z, Xie M, Ye K. Asparagine endopeptidase is an innovative therapeutic target for neurodegenerative diseases. Expert Opin Ther Targets 2016; 20:1237-45. [PMID: 27115710 DOI: 10.1080/14728222.2016.1182990] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Asparagine endopeptidase (AEP) is a pH-dependent endolysosomal cysteine protease that cleaves its substrates after asparagine residues. Our most recent study identifies that it possesses the delta-secretase activity, and that it is implicated in numerous neurological diseases such as Alzheimer's disease (AD) and stroke. Accumulating evidence supports that the inhibition of AEP exhibits beneficial effects for treating these devastating diseases. AREAS COVERED Based on recent evidence, it is clear that AEP cleaves its substrate, such as amyloid precursor protein (APP), tau and SET, and plays a critical role in neuronal cell death in various neurodegenerative diseases and stroke. In this article, the basic biology of AEP, its knockout phenotypes in mouse models, its substrates in neurodegenerative diseases, and its small peptidyl inhibitors and prodrugs are discussed. In addition, we discuss the potential of AEP as a novel therapeutic target for neurodegenerative diseases. EXPERT OPINION AEP plays a unique role in numerous biological processes, depending on both pH and context. Most striking is our most recent finding; that AEP is activated in an age-dependent manner and simultaneously cleaves both APP and tau, thereby unifying both major pathological events in AD. Thus, AEP acts as an innovative trigger for neurodegenerative diseases. Inhibition of AEP will provide a disease-modifying treatment for neurodegenerative diseases including AD.
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Affiliation(s)
- Zhentao Zhang
- a Department of Neurology , Renmin Hospital of Wuhan University , Wuhan , China.,b Department of Pathology and Laboratory Medicine , Emory University School of Medicine , Atlanta , GA , USA
| | - Manling Xie
- b Department of Pathology and Laboratory Medicine , Emory University School of Medicine , Atlanta , GA , USA
| | - Keqiang Ye
- b Department of Pathology and Laboratory Medicine , Emory University School of Medicine , Atlanta , GA , USA
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12
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Jin N, Yin X, Yu D, Cao M, Gong CX, Iqbal K, Ding F, Gu X, Liu F. Truncation and activation of GSK-3β by calpain I: a molecular mechanism links to tau hyperphosphorylation in Alzheimer's disease. Sci Rep 2015; 5:8187. [PMID: 25641096 PMCID: PMC4313118 DOI: 10.1038/srep08187] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 01/07/2015] [Indexed: 12/17/2022] Open
Abstract
Abnormal hyperphosphorylation of tau is pivotally involved in the pathogenesis of Alzheimer's disease (AD) and related tauopathies. Glycogen synthase kinase 3β (GSK-3β) is a primary tau kinase that is most implicated in tau pathology in AD. However, the exact molecular nature of GSK-3β involved in AD is unclear. In the present study, we found that GSK-3β was truncated at C-terminus and correlated with over-activation of calpain I in AD brain. Truncation of GSK-3β was positively correlated with tau hyperphosphorylation, tangles score and Braak stage in human brain. Calpain I proteolyzed GSK-3β in vitro at C-terminus, leading to an increase of its kinase activity, but keeping its characteristic to preferentially phosphorylate the protein kinase A-primed tau. Excitotoxicity induced by kainic acid (KA) caused GSK-3β truncation at C-terminus and hyperphosphorylation of tau in mouse brain. Inhibition of calpain prevented the KA-induced changes. These findings suggest that truncation of GSK-3β by Ca2+/calpain I markedly increases its activity and involvement of this mechanism probably is responsible for up-regulation of GSK-3β and consequent abnormal hyperphosphorylation of tau and neurofibrillary degeneration in AD.
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Affiliation(s)
- Nana Jin
- 1] Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, P. R. China [2] Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA
| | - Xiaomin Yin
- 1] Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, P. R. China [2] Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA
| | - Dian Yu
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA
| | - Maohong Cao
- Institute of Neurology, Department of Neurology, Hospital Affiliated to Nantong University, Nantong, Jiangsu 226001, P. R. China
| | - Cheng-Xin Gong
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA
| | - Khalid Iqbal
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA
| | - Fei Ding
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, P. R. China
| | - Xiaosong Gu
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, P. R. China
| | - Fei Liu
- 1] Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, P. R. China [2] Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA
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13
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Lee JY, Taghian K, Petratos S. Axonal degeneration in multiple sclerosis: can we predict and prevent permanent disability? Acta Neuropathol Commun 2014; 2:97. [PMID: 25159125 PMCID: PMC4243718 DOI: 10.1186/s40478-014-0097-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 08/06/2014] [Indexed: 12/24/2022] Open
Abstract
Axonal degeneration is a major determinant of permanent neurological impairment during multiple sclerosis (MS). Due to the variable course of clinical disease and the heterogeneity of MS lesions, the mechanisms governing axonal degeneration may differ between disease stages. While the etiology of MS remains elusive, there now exist potential prognostic biomarkers that can predict the conversion to clinically definite MS. Specialized imaging techniques identifying axonal injury and drop-out are becoming established in clinical practice as a predictive measure of MS progression, such as optical coherence tomography (OCT) or diffusion tensor imaging (DTI). However, these imaging techniques are still being debated as predictive biomarkers since controversy surrounds their lesion-specific association with expanded disability status scale (EDSS). A more promising diagnostic measure of axonal degeneration has been argued for the detection of reduced N-acetyl aspartate (NAA) and Creatine ratios via magnetic resonance spectroscopic (MRS) imaging, but again fail with its specificity for predicting actual axonal degeneration. Greater accuracy of predictive biomarkers is therefore warranted and may include CSF neurofilament light chain (NF-L) and neurofilament heavy chain (NF-H) levels, for progressive MS. Furthermore, defining the molecular mechanisms that occur during the neurodegenerative changes in the various subgroups of MS may in fact prove vital for the future development of efficacious neuroprotective therapies. The clinical translation of a combined Na+ and Ca2+ channel blocker may lead to the establishment of a bona fide neuroprotective agent for the treatment of progressive MS. However, more specific therapeutic targets to limit axonal damage in MS need investigation and may include such integral axonal proteins such as the collapsin response mediator protein-2 (CRMP-2), a molecule which upon post-translational modification may propagate axonal degeneration in MS. In this review, we discuss the current clinical determinants of axonal damage in MS and consider the cellular and molecular mechanisms that may initiate these neurodegenerative changes. In particular we highlight the therapeutic candidates that may formulate novel therapeutic strategies to limit axonal degeneration and EDSS during progressive MS.
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14
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Ward SM, Himmelstein DS, Lancia JK, Fu Y, Patterson KR, Binder LI. TOC1: characterization of a selective oligomeric tau antibody. J Alzheimers Dis 2014; 37:593-602. [PMID: 23979027 DOI: 10.3233/jad-131235] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The work presented herein addresses a specific portion of the tau pathology, pre-fibrillar oligomers, now thought to be important pathological components in Alzheimer's disease and other neurodegenerative tauopathies. In previous work, we generated an antibody against purified recombinant cross-linked tau dimers, called Tau Oligomeric Complex 1 (TOC1). TOC1 recognizes tau oligomers and its immunoreactivity is elevated in Alzheimer's disease brains. In this report, we expand upon the previous study to show that TOC1 selectively labels tau oligomers over monomers or polymers, and that TOC1 is also reactive in other neurodegenerative tauopathies. Using a series of deletion mutants spanning the tau molecule, we further demonstrate that TOC1 has one continuous epitope located within amino acids 209-224, in the so-called proline rich region. Together with the previous study, our data indicates that TOC1 is a conformation-dependent antibody whose epitope is revealed upon dimerization and oligomerization, but concealed again as polymers form. This characterization of the TOC1 antibody further supports its potential as a powerful biochemical tool that can be used to better investigate the involvement of tau in neurodegenerative diseases.
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Affiliation(s)
- Sarah M Ward
- MSU-College of Human Medicine. Department of Translational Science and Molecular Medicine, Grand Rapids, MI, USA
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15
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The C-Terminus of Tau Protein Plays an Important Role in Its Stability and Toxicity. J Mol Neurosci 2014; 55:251-259. [DOI: 10.1007/s12031-014-0314-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 04/16/2014] [Indexed: 10/25/2022]
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16
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Insulin therapy modulates mitochondrial dynamics and biogenesis, autophagy and tau protein phosphorylation in the brain of type 1 diabetic rats. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1154-66. [PMID: 24747740 DOI: 10.1016/j.bbadis.2014.04.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 04/08/2014] [Accepted: 04/10/2014] [Indexed: 01/22/2023]
Abstract
The main purpose of this study was to examine whether streptozotocin (STZ)-induced type 1 diabetes (T1D) and insulin (INS) treatment affect mitochondrial function, fission/fusion and biogenesis, autophagy and tau protein phosphorylation in cerebral cortex from diabetic rats treated or not with INS. No significant alterations were observed in mitochondrial function as well as pyruvate levels, despite the significant increase in glucose levels observed in INS-treated diabetic rats. A significant increase in DRP1 protein phosphorylated at Ser616 residue was observed in the brain cortex of STZ rats. Also an increase in NRF2 protein levels and in the number of copies of mtDNA were observed in STZ diabetic rats, these alterations being normalized by INS. A slight decrease in LC3-II levels was observed in INS-treated rats when compared to STZ diabetic animals. An increase in tau protein phosphorylation at Ser396 residue was observed in STZ diabetic rats while INS treatment partially reversed that effect. Accordingly, a modest reduction in the activation of GSK3β and a significant increase in the activity of phosphatase 2A were found in INS-treated rats when compared to STZ diabetic animals. No significant alterations were observed in caspases 9 and 3 activity and synaptophysin and PSD95 levels. Altogether our results show that mitochondrial alterations induced by T1D seem to involve compensation mechanisms since no significant changes in mitochondrial function and synaptic integrity were observed in diabetic animals. In addition, INS treatment is able to normalize the alterations induced by T1D supporting the importance of INS signaling in the brain.
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17
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Ma M. Role of calpains in the injury-induced dysfunction and degeneration of the mammalian axon. Neurobiol Dis 2013; 60:61-79. [PMID: 23969238 PMCID: PMC3882011 DOI: 10.1016/j.nbd.2013.08.010] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/17/2013] [Accepted: 08/08/2013] [Indexed: 12/21/2022] Open
Abstract
Axonal injury and degeneration, whether primary or secondary, contribute to the morbidity and mortality seen in many acquired and inherited central nervous system (CNS) and peripheral nervous system (PNS) disorders, such as traumatic brain injury, spinal cord injury, cerebral ischemia, neurodegenerative diseases, and peripheral neuropathies. The calpain family of proteases has been mechanistically linked to the dysfunction and degeneration of axons. While the direct mechanisms by which transection, mechanical strain, ischemia, or complement activation trigger intra-axonal calpain activity are likely different, the downstream effects of unregulated calpain activity may be similar in seemingly disparate diseases. In this review, a brief examination of axonal structure is followed by a focused overview of the calpain family. Finally, the mechanisms by which calpains may disrupt the axonal cytoskeleton, transport, and specialized domains (axon initial segment, nodes, and terminals) are discussed.
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Affiliation(s)
- Marek Ma
- Department of Emergency Medicine, University of Pennsylvania, Philadelphia, PA, USA; Center for Resuscitation Science, University of Pennsylvania, Philadelphia, PA, USA.
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18
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Jadhav S, Zilka N, Novak M. Protein truncation as a common denominator of human neurodegenerative foldopathies. Mol Neurobiol 2013; 48:516-32. [PMID: 23516100 DOI: 10.1007/s12035-013-8440-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 03/05/2013] [Indexed: 12/13/2022]
Abstract
Neurodegenerative foldopathies are characterized by aberrant folding of diseased modified proteins, which are major constituents of the intracellular and extracellular lesions. These lesions correlate with the cognitive and/or motor impairment seen in these diseases. The majority of the disease modified proteins in neurodegenerative foldopathies belongs to the group of proteins termed as intrinsically disordered proteins (IDPs). Several independent studies have showed that abnormal protein processing constitutes the key pathological feature of these disorders. The current review focuses on protein truncation as a common denominator of neurodegenerative foldopathies, which is considered to be the major driving force behind the pathological metamorphosis of brain IDPs. The aim of the review is to emphasize the key role of the protein truncation in the pathogenic pathways of neurodegenerative diseases. A deeper understanding of the complex downstream processing of the IDPs, resulting in the generation of pathologically modified proteins might be a prerequisite for the successful therapeutic strategies of several fatal neurodegenerative diseases.
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Affiliation(s)
- Santosh Jadhav
- Institute of Neuroimmunology, Slovak Academy of Sciences, Centre of Excellence for Alzheimer's Disease and Related Disorders, Dubravska cesta 9, 845 10, Bratislava, Slovak Republic
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19
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Fan YX, Zhang Y, Shen HB. LabCaS: labeling calpain substrate cleavage sites from amino acid sequence using conditional random fields. Proteins 2012. [PMID: 23180633 DOI: 10.1002/prot.24217] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The calpain family of Ca(2+) -dependent cysteine proteases plays a vital role in many important biological processes which is closely related with a variety of pathological states. Activated calpains selectively cleave relevant substrates at specific cleavage sites, yielding multiple fragments that can have different functions from the intact substrate protein. Until now, our knowledge about the calpain functions and their substrate cleavage mechanisms are limited because the experimental determination and validation on calpain binding are usually laborious and expensive. In this work, we aim to develop a new computational approach (LabCaS) for accurate prediction of the calpain substrate cleavage sites from amino acid sequences. To overcome the imbalance of negative and positive samples in the machine-learning training which have been suffered by most of the former approaches when splitting sequences into short peptides, we designed a conditional random field algorithm that can label the potential cleavage sites directly from the entire sequences. By integrating the multiple amino acid features and those derived from sequences, LabCaS achieves an accurate recognition of the cleave sites for most calpain proteins. In a jackknife test on a set of 129 benchmark proteins, LabCaS generates an AUC score 0.862. The LabCaS program is freely available at: http://www.csbio.sjtu.edu.cn/bioinf/LabCaS. Proteins 2013. © 2012 Wiley Periodicals, Inc.
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Affiliation(s)
- Yong-Xian Fan
- Department of Automation, Shanghai Jiao Tong University, and Key Laboratory of System Control and Information Processing, Ministry of Education of China, Shanghai 200240, China
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20
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Lee S, Shea TB. Regulation of tau proteolysis by phosphatases. Brain Res 2012; 1495:30-6. [PMID: 23159717 DOI: 10.1016/j.brainres.2012.10.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 10/09/2012] [Accepted: 10/11/2012] [Indexed: 01/06/2023]
Abstract
One pathological hallmark of Alzheimer's disease is the accumulation of highly phosphorylated tau. Since tau phosphorylation inhibits its proteolysis, we examined the impact of endogenous phosphatase activities on tau proteolysis by homogenization of cultured cells and 3xTg-AD mouse brain followed by incubation with or without phosphatase inhibitors. Incubation without phosphatase inhibitors significantly increased tau immunoreactivity against antibody C3 (which reacts with tau truncated at D421), and increased the generation of tau breakdown products. These changes were augmented by lithium treatment and inhibited by constitutively active GSK3β. These findings underscore that tau proteolysis is regulated by a balance of kinase and phosphatase activities.
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Affiliation(s)
- Sangmook Lee
- University of Massachusetts Lowell, Department of Biological Sciences, Center for Cellular Neurobiology and Neurodegeneration Research, One University Avenue, Lowell, MA 01854, USA
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21
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Ferreira A. Calpain dysregulation in Alzheimer's disease. ISRN BIOCHEMISTRY 2012; 2012:728571. [PMID: 25969760 PMCID: PMC4393001 DOI: 10.5402/2012/728571] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Accepted: 09/12/2012] [Indexed: 11/23/2022]
Abstract
Alzheimer's disease (AD) is characterized by the presence of senile plaques and neurofibrillary tangles in the neocortex and hippocampus of AD patients. In addition, a marked decrease in synaptic contacts has been detected in these affected brain areas. Due to its prevalence in the aging population, this disease has been the focus of numerous studies. The data obtained from those studies suggest that the mechanisms leading to the formation of the hallmark lesions of AD might be linked. One of such mechanisms seems to be the dysregulation of calcium homeostasis that results in the abnormal activation of calpains. Calpains are a family of Ca(2+)-dependent cysteine proteases that play a key role in multiple cell functions including cell development, differentiation and proliferation, axonal guidance, growth cone motility, and cell death, among others. In this paper, we briefly reviewed data on the structure of these proteases and their regulation under normal conditions. We also summarized data underscoring the participation of calpains in the neurodegenerative mechanisms associated with AD.
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Affiliation(s)
- Adriana Ferreira
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Avenue, Ward 8-140, Chicago, IL 60611, USA
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22
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Ma M, Shofer FS, Neumar RW. Calpastatin overexpression protects axonal transport in an in vivo model of traumatic axonal injury. J Neurotrauma 2012; 29:2555-63. [PMID: 22776025 DOI: 10.1089/neu.2012.2473] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Traumatic brain injury (TBI) causes substantial morbidity and mortality worldwide. A key component of both mild and severe TBI is diffuse axonal injury. Except in cases of extreme mechanical strain, when axons are torn at the moment of trauma, axonal stretch injury is characterized by early cytoskeletal proteolysis, transport disruption, and secondary axotomy. Calpains, a family of Ca(2+)-dependent proteases, have been implicated in this pathologic cascade, but direct in vivo evidence is lacking. To test the hypothesis that calpains play a causal role in axonal stretch injury in vivo, we used our rat optic nerve stretch model following adeno-associated viral (AAV) vector-mediated overexpression of the endogenous calpain inhibitor calpastatin in optic nerve axons. AAV vectors were designed for optimal expression of human calpastatin (hCAST) in retinal ganglion cells (RGCs). Calpain inhibition by the expressed protein was then confirmed in primary cortical cultures. Finally, we performed bilateral intravitreal injections of AAV vectors expressing hCAST or the reporter protein ZsGreen 3 weeks prior to unilateral optic nerve stretch. Immediately after stretch injury, Fluoro-Gold was injected into the superior colliculi for assessment of retrograde axonal transport. Rats were euthanized 4 days after stretch injury. Both hCAST and ZsGreen were detected in axons throughout the optic nerve to the chiasm. Calpastatin overexpression partially preserved axonal transport after stretch injury (58.3±15.6% reduction in Fluoro-Gold labeling relative to uninjured contralateral controls in ZsGreen-expressing RGCs, versus 33.8±23.9% in hCAST-expressing RGCs; p=0.038). These results provide direct evidence that axonal calpains play a causal role in transport disruption after in vivo stretch injury.
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Affiliation(s)
- Marek Ma
- Department of Emergency Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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23
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Tau Phosphorylation by GSK3 in Different Conditions. Int J Alzheimers Dis 2012; 2012:578373. [PMID: 22675648 PMCID: PMC3362846 DOI: 10.1155/2012/578373] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 03/15/2012] [Indexed: 11/18/2022] Open
Abstract
Almost a 20% of the residues of tau protein are phosphorylatable amino acids: serine, threonine, and tyrosine. In this paper we comment on the consequences for tau of being a phosphoprotein. We will focus on serine/threonine phosphorylation. It will be discussed that, depending on the modified residue in tau molecule, phosphorylation could be protective, in processes like hibernation, or toxic like in development of those diseases known as tauopathies, which are characterized by an hyperphosphorylation and aggregation of tau.
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Iwaya N, Akiyama K, Goda N, Tenno T, Fujiwara Y, Hamada D, Ikura T, Shirakawa M, Hiroaki H. Effect of Ca2+ on the microtubule-severing enzyme p60-katanin. Insight into the substrate-dependent activation mechanism. FEBS J 2012; 279:1339-52. [PMID: 22325007 DOI: 10.1111/j.1742-4658.2012.08528.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Katanin p60 (p60-katanin) is a microtubule (MT)-severing enzyme and its activity is regulated by the p80 subunit (adaptor-p80). p60-katanin consists of an N-terminal domain, followed by a single ATPase associated with various cellular activities (AAA) domain. We have previously shown that the N-terminal domain serves as the binding site for MT, the substrate of p60-katanin. In this study, we show that the same domain shares another interface with the C-terminal domain of adaptor-p80. We further show that Ca(2+) ions inhibit the MT-severing activity of p60-katanin, whereas the MT-binding activity is preserved in the presence of Ca(2+). In detail, the basal ATPase activity of p60-katanin is stimulated twofold by both MTs and the C-terminal domain of adaptor-p80, whereas Ca(2+) reduces elevated ATPase activity to the basal level. We identify the Ca(2+) -binding site at the end of helix 2 of the N-terminal domain, which is different from the MT-binding interface. On the basis of these observations, we propose a speculative model in which spatial rearrangement of the N-terminal domain relative to the C-terminal AAA domain may be important for productive ATP hydrolysis towards MT-severing. Our model can explain how Ca(2+) regulates both severing and ATP hydrolysis activity, because the Ca(2+) -binding site on the N-terminal domain moves close to the AAA domain during MT severing.
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Affiliation(s)
- Naoko Iwaya
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto, Japan
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25
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Guttmann RP, Ghoshal S. Thiol-protease oxidation in age-related neuropathology. Free Radic Biol Med 2011; 51:282-8. [PMID: 21565267 DOI: 10.1016/j.freeradbiomed.2011.04.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 04/07/2011] [Accepted: 04/07/2011] [Indexed: 11/27/2022]
Abstract
Increased oxidative stress is a hallmark of every major neurodegenerative disease that has been studied. Numerous biomarkers of oxidative stress have been found, indicating that waves of oxidation had, at one time or another, overwhelmed antioxidant defenses, leaving behind a host of oxidized DNA, lipids, and proteins in their path. Although some level of oxidation may be beneficial, perhaps mediated by a hormetic response, the extent and types of oxidation detected in neuropathological states would suggest that oxidative stress contributes to a loss of homeostasis and cellular dysfunction. Although there are many targets of oxidants, this review emphasizes protein oxidation with a focus on an important group of redox-sensitive enzymes, the thiol-proteases. Both the direct and the indirect effects of oxidation and their potential importance in neurodegeneration are considered.
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Affiliation(s)
- Rodney P Guttmann
- Department of Gerontology, and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA.
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26
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Kayed R, Jackson GR, Estes DM, Barrett ADT. Alzheimers disease: review of emerging treatment role for intravenous immunoglobulins. J Cent Nerv Syst Dis 2011; 3:67-73. [PMID: 23861639 PMCID: PMC3663607 DOI: 10.4137/jcnsd.s5018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common neurodegenerative disorder. Currently available therapies are symptomatic but do not alter underlying disease progression. Immunotherapeutic approaches such as anti Aβ peptide active vaccination trials have had limited success to date. Intravenous immunoblobulin (IVIg) is widely used in immune-mediated neurological disorders such myasthenia gravis and Guillain-Barre syndrome. These preparations have been obtained from the pooled plasma of healthy human donors and contain natural anti-amyloid antibodies and are well tolerated. A small pilot study of passive immunotherapy using IVIg has suggested cognitive improvement. A multicenter phase III trial is ongoing and will determine whether or not this treatment can ameliorate cognitive deficits in mild-to-moderate AD. Here, we briefly review the pathogenic role of amyloid and tau in AD, as well as immunotherapeutic efforts to date. We also summarize what is known about naturally occurring anti-Aβ and tau antibodies in IVIg with a view toward explaining potential mechanisms underlying their therapeutic effects.
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Affiliation(s)
- Rakez Kayed
- Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, Galveston, TX, USA. ; Department of Neurology, University of Texas Medical Branch, Galveston, TX, USA. ; Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX, USA
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27
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Cheng Liu M, Kobeissy F, Zheng W, Zhang Z, Hayes RL, Wang KKW. Dual vulnerability of tau to calpains and caspase-3 proteolysis under neurotoxic and neurodegenerative conditions. ASN Neuro 2011; 3:e00051. [PMID: 21359008 PMCID: PMC3040574 DOI: 10.1042/an20100012] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 08/31/2010] [Accepted: 09/22/2010] [Indexed: 12/21/2022] Open
Abstract
Axonally specific microtubule-associated protein tau is an important component of neurofibrillary tangles found in AD (Alzheimer's disease) and other tauopathy diseases such as CTE (chronic traumatic encephalopathy). Such tau aggregate is found to be hyperphosphorylated and often proteolytically fragmented. Similarly, tau is degraded following TBI (traumatic brain injury). In the present study, we examined the dual vulnerability of tau to calpain and caspase-3 under neurotoxic and neurodegenerative conditions. We first identified three novel calpain cleavage sites in rat tau (four-repeat isoform) as Ser130↓Lys131, Gly157↓Ala158 and Arg380↓Glu381. Fragment-specific antibodies to target the major calpain-mediated TauBDP-35K (35 kDa tau-breakdown product) and the caspase-mediated TauBDP-45K respectively were developed. In rat cerebrocortical cultures treated with excitotoxin [NMDA (N-methyl-D-aspartate)], tau is significantly degraded into multiple fragments, including a dominant signal of calpain-mediated TauBDP-35K with minimal caspase-mediated TauBDP-45K. Following apoptosis-inducing EDTA treatment, tau was truncated only to TauBDP-48K/45K-exclusively by caspase. Cultures treated with another apoptosis inducer STS (staurosporine), dual fragmentation by calpain (TauBDP-35K) and caspase-3 (TauBDP-45K) was observed. Tau was also fragmented in injured rat cortex following TBI in vivo to BDPs of 45-42 kDa (minor), 35 kDa and 15 kDa, followed by TauBDP-25K. Calpain-mediated TauBDP-35K-specific antibody confirmed robust signals in the injured cortex, while caspase-mediated TauBDP-45K-specific antibody only detected faint signals. Furthermore, intravenous administration of a calpain-specific inhibitor SNJ-1945 strongly suppressed the TauBDP-35K formation. Taken together, these results suggest that tau protein is dually vulnerable to calpain and caspase-3 proteolysis under different neurotoxic and injury conditions.
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Key Words
- AD, Alzheimer's disease
- CCI, controlled cortical impact
- CSF, colony-stimulating factor
- CTE, chronic traumatic encephalopathy
- DMEM, Dulbecco's modified Eagle's medium
- DTT, dithiothreitol
- NMDA, N-methyl-d-aspartate
- STS, staurosporine
- TAI, traumatic axonal injury
- TBI, traumatic brain injury
- TBST, TBS and 0.05% Tween-2
- TauBDP-35K, 35 kDa tau-breakdown product
- cell death
- neurodegeneration
- protease
- tau protein
- tauopathy
- traumatic brain injury (TBI)
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Affiliation(s)
- Ming Cheng Liu
- *Center of Innovative Research, Banyan Biomarkers Inc., 12085 Research Drive, Alachua, FL 32615, U.S.A
| | - Firas Kobeissy
- *Center of Innovative Research, Banyan Biomarkers Inc., 12085 Research Drive, Alachua, FL 32615, U.S.A
- †Department of Psychiatry, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, U.S.A
| | - Wenrong Zheng
- *Center of Innovative Research, Banyan Biomarkers Inc., 12085 Research Drive, Alachua, FL 32615, U.S.A
| | - Zhiqun Zhang
- *Center of Innovative Research, Banyan Biomarkers Inc., 12085 Research Drive, Alachua, FL 32615, U.S.A
| | - Ronald L Hayes
- *Center of Innovative Research, Banyan Biomarkers Inc., 12085 Research Drive, Alachua, FL 32615, U.S.A
- ‡Department of Anesthesiology, University of Florida, Gainesville, FL 32610, U.S.A
| | - Kevin KW Wang
- *Center of Innovative Research, Banyan Biomarkers Inc., 12085 Research Drive, Alachua, FL 32615, U.S.A
- †Department of Psychiatry, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, U.S.A
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Abstract
Tau aggregation is a hallmark of several neurodegenerative diseases, including AD (Alzheimer's disease), although the mechanism underlying tau aggregation remains unclear. Recent studies show that the proteolysis of tau plays an important role in both tau aggregation and neurodegeneration. On one hand, truncation of tau may generate amyloidogenic tau fragments that initiate the aggregation of tau, which in turn can cause toxicity. On the other hand, truncation of tau may result in tau fragments which induce neurodegeneration through unknown mechanisms, independently of tau aggregation. Blocking the truncation of tau thus may represent a promising therapeutic approach for AD or other tauopathies. In the present paper, we summarize our data on tau cleavage in a cell model of tauopathy and major results on tau cleavage reported in the literature.
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Garg S, Timm T, Mandelkow EM, Mandelkow E, Wang Y. Cleavage of Tau by calpain in Alzheimer's disease: the quest for the toxic 17 kD fragment. Neurobiol Aging 2010; 32:1-14. [PMID: 20961659 DOI: 10.1016/j.neurobiolaging.2010.09.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 09/06/2010] [Accepted: 09/10/2010] [Indexed: 12/26/2022]
Abstract
The amyloid cascade hypothesis of Alzheimer's disease (AD) posits that the generation of β-amyloid (Aβ) triggers Tau neurofibrillary pathology. Recently a "17 kD" calpain-induced Tau fragment, comprising residues 45-230 (molecular weight [MW], 18.7 kD), was proposed to mediate Aβ-induced toxicity. Here, we demonstrate that the "17 kD" fragment is actually much smaller, containing residues 125-230 (molecular weight, 10.7 kD). Inducing Tau phosphorylation by okadaic acid or mimicking phosphorylation by Glu mutations at the epitopes of Alzheimer-diagnostic antibodies AT100/AT8/PHF1 could not prevent the generation of this fragment. The fragment can be induced not only by Aβ oligomers, but also by other cell stressors, e.g., thapsigargin (a Ca(2+)-ATPase inhibitor) or glutamate (an excitatory neurotransmitter). However, overexpression of neither Tau(45-230) nor Tau(125-230) fragment is toxic to Chinese hamster ovary (CHO) cells, neuroblastoma cells (N2a) or primary hippocampal neurons. Finally, the calpain-induced fragment can be observed both in Alzheimer's disease brains and in control normal human brains. We conclude that the 17 kD Tau fragment is not a mediator of Aβ-induced toxicity, leaving open the possibility that upstream calpain activation might cause both Tau fragmentation and toxicity.
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Affiliation(s)
- Sarika Garg
- Max-Planck-Unit for Structural Molecular Biology, Hamburg, Germany
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30
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Abstract
Deposition of highly phosphorylated tau in the brain is the most significant neuropathological and biochemical characteristic of the group of neurodegenerative disorders termed the tauopathies. The discovery of tau fragments in these diseases suggests that tau cleavage and tau phosphorylation, both of which induce conformational changes in tau, could each have roles in disease pathogenesis. The identities of the proteases responsible for degrading tau, resulting in the appearance of truncated tau species in physiological and pathological conditions, are not known. Several fragments of tau are reported to have pro-aggregation properties, but the lack of disease-relevant cell models of tau aggregation has hampered investigation of the effects of tau aggregation on normal cellular functioning. In the present paper, we describe our findings of N-terminally truncated tau in the brain in a subgroup of the tauopathies in which tau isoforms containing four microtubule-binding domains predominate. We also discuss the evidence for the involvement of proteases in the generation of tau pathology in neurodegenerative disease, since these enzymes warrant further investigation as potential therapeutic targets in the tauopathies.
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Nakajima T, Ochi S, Oda C, Ishii M, Ogawa K. Ischemic preconditioning attenuates of ischemia-induced degradation of spectrin and tau: implications for ischemic tolerance. Neurol Sci 2010; 32:229-39. [DOI: 10.1007/s10072-010-0359-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 06/15/2010] [Indexed: 10/19/2022]
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Avila J, Santa-María I, Pérez M, Hernández F, Moreno F. Tau phosphorylation, aggregation, and cell toxicity. J Biomed Biotechnol 2010; 2006:74539. [PMID: 17047313 PMCID: PMC1479889 DOI: 10.1155/jbb/2006/74539] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Protein aggregation takes place in many neurodegenerative disorders. However, there is a controversy about the possible toxicity of these protein aggregates. In this review, this controversy is discussed, focussing on the tau aggregation that takes place in those disorders known as tauopathies.
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Affiliation(s)
- J. Avila
- Centro de Biología Molecular “Severo Ochoa,”
Facultad de Ciencias, Universidad Autónoma de Madrid, Campus
de Cantoblanco, 28049 Madrid, Spain
- *J. Avila:
| | - I. Santa-María
- Centro de Biología Molecular “Severo Ochoa,”
Facultad de Ciencias, Universidad Autónoma de Madrid, Campus
de Cantoblanco, 28049 Madrid, Spain
| | - M. Pérez
- Centro de Biología Molecular “Severo Ochoa,”
Facultad de Ciencias, Universidad Autónoma de Madrid, Campus
de Cantoblanco, 28049 Madrid, Spain
| | - F. Hernández
- Centro de Biología Molecular “Severo Ochoa,”
Facultad de Ciencias, Universidad Autónoma de Madrid, Campus
de Cantoblanco, 28049 Madrid, Spain
| | - F. Moreno
- Centro de Biología Molecular “Severo Ochoa,”
Facultad de Ciencias, Universidad Autónoma de Madrid, Campus
de Cantoblanco, 28049 Madrid, Spain
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Hanisch K, Soininen H, Alafuzoff I, Hoffmann R. Analysis of Human Tau in Cerebrospinal Fluid. J Proteome Res 2010; 9:1476-82. [DOI: 10.1021/pr901002t] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Katja Hanisch
- Institute of Bioanalytical Chemistry, Center for Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig Universität, 04103 Leipzig, Germany, Department of Neurology, Kuopio University, Kuopio, Finland, and Section of Neuropathology, Kuopio University, Kuopio, Finland, Department of Genetics and Pathology, Uppsala University, S-75185, Uppsala, Sweden
| | - Hilkka Soininen
- Institute of Bioanalytical Chemistry, Center for Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig Universität, 04103 Leipzig, Germany, Department of Neurology, Kuopio University, Kuopio, Finland, and Section of Neuropathology, Kuopio University, Kuopio, Finland, Department of Genetics and Pathology, Uppsala University, S-75185, Uppsala, Sweden
| | - Irina Alafuzoff
- Institute of Bioanalytical Chemistry, Center for Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig Universität, 04103 Leipzig, Germany, Department of Neurology, Kuopio University, Kuopio, Finland, and Section of Neuropathology, Kuopio University, Kuopio, Finland, Department of Genetics and Pathology, Uppsala University, S-75185, Uppsala, Sweden
| | - Ralf Hoffmann
- Institute of Bioanalytical Chemistry, Center for Biotechnology and Biomedicine, Faculty of Chemistry and Mineralogy, Leipzig Universität, 04103 Leipzig, Germany, Department of Neurology, Kuopio University, Kuopio, Finland, and Section of Neuropathology, Kuopio University, Kuopio, Finland, Department of Genetics and Pathology, Uppsala University, S-75185, Uppsala, Sweden
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Profiling of calpain activity with a series of FRET-based substrates. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1505-9. [DOI: 10.1016/j.bbapap.2009.06.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 06/15/2009] [Accepted: 06/16/2009] [Indexed: 11/21/2022]
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Hernández F, Gómez de Barreda E, Fuster-Matanzo A, Lucas JJ, Avila J. GSK3: a possible link between beta amyloid peptide and tau protein. Exp Neurol 2009; 223:322-5. [PMID: 19782073 DOI: 10.1016/j.expneurol.2009.09.011] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 09/04/2009] [Accepted: 09/17/2009] [Indexed: 12/30/2022]
Abstract
Tau is a neuronal microtubule-associated phosphoprotein that is highly phosphorylated by glycogen synthase kinase 3 (GSK3). Tau phosphorylation by GSK3 regulates tau binding to microtubules, tau degradation and tau aggregation. Tau phosphorylation is important in Alzheimer disease pathology and in other tauopathies. In Alzheimer disease, it has been proposed that the peptide beta amyloid promotes GSK3 activation, resulting in tau phosphorylation. In this work, we review the links between beta amyloid peptide, tau protein and GSK3 that occur in familial Alzheimer disease. We also discuss the possible links between GSK3 and sporadic Alzheimer disease. Finally, we include a brief review of the pathology of animal models overexpressing GSK3.
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Affiliation(s)
- Félix Hernández
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), C/Nicolás Cabrera, 1 Campus Cantoblanco, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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Marambaud P, Dreses-Werringloer U, Vingtdeux V. Calcium signaling in neurodegeneration. Mol Neurodegener 2009; 4:20. [PMID: 19419557 PMCID: PMC2689218 DOI: 10.1186/1750-1326-4-20] [Citation(s) in RCA: 223] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 05/06/2009] [Indexed: 12/16/2022] Open
Abstract
Calcium is a key signaling ion involved in many different intracellular and extracellular processes ranging from synaptic activity to cell-cell communication and adhesion. The exact definition at the molecular level of the versatility of this ion has made overwhelming progress in the past several years and has been extensively reviewed. In the brain, calcium is fundamental in the control of synaptic activity and memory formation, a process that leads to the activation of specific calcium-dependent signal transduction pathways and implicates key protein effectors, such as CaMKs, MAPK/ERKs, and CREB. Properly controlled homeostasis of calcium signaling not only supports normal brain physiology but also maintains neuronal integrity and long-term cell survival. Emerging knowledge indicates that calcium homeostasis is not only critical for cell physiology and health, but also, when deregulated, can lead to neurodegeneration via complex and diverse mechanisms involved in selective neuronal impairments and death. The identification of several modulators of calcium homeostasis, such as presenilins and CALHM1, as potential factors involved in the pathogenesis of Alzheimer's disease, provides strong support for a role of calcium in neurodegeneration. These observations represent an important step towards understanding the molecular mechanisms of calcium signaling disturbances observed in different brain diseases such as Alzheimer's, Parkinson's, and Huntington's diseases.
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Affiliation(s)
- Philippe Marambaud
- Litwin-Zucker Research Center for the Study of Alzheimer's Disease, The Feinstein Institute for Medical Research, North Shore-LIJ, Manhasset, New York 11030, USA.
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O-GlcNAc cycling: implications for neurodegenerative disorders. Int J Biochem Cell Biol 2009; 41:2134-46. [PMID: 19782947 DOI: 10.1016/j.biocel.2009.03.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2009] [Revised: 03/13/2009] [Accepted: 03/18/2009] [Indexed: 12/20/2022]
Abstract
The dynamic post-translational modification of proteins by O-linked N-acetylglucosamine (O-GlcNAc), termed O-GlcNAcylation, is an important mechanism for modulating cellular signaling pathways. O-GlcNAcylation impacts transcription, translation, organelle trafficking, proteasomal degradation and apoptosis. O-GlcNAcylation has been implicated in the etiology of several human diseases including type-2 diabetes and neurodegeneration. This review describes the pair of enzymes responsible for the cycling of this post-translational modification: O-GlcNAc transferase (OGT) and beta-N-acetylglucosaminidase (OGA), with a focus on the function of their structural domains. We will also highlight the important processes and substrates regulated by these enzymes, with an emphasis on the role of O-GlcNAc as a nutrient sensor impacting insulin signaling and the cellular stress response. Finally, we will focus attention on the many ways by which O-GlcNAc cycling may affect the cellular machinery in the neuroendocrine and central nervous systems.
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Cox CD, West EJ, Liu MC, Wang KK, Hayes RL, Lyeth BG. Dicyclomine, an M1 muscarinic antagonist, reduces biomarker levels, but not neuronal degeneration, in fluid percussion brain injury. J Neurotrauma 2008; 25:1355-65. [PMID: 19061379 PMCID: PMC2652836 DOI: 10.1089/neu.2008.0671] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recent studies indicate that alphaII-spectrin breakdown products (SBDPs) have utility as biological markers of traumatic brain injury (TBI). However, the utility of SBDP biomarkers for detecting effects of therapeutic interventions has not been explored. Acetylcholine plays a role in pathological neuronal excitation and TBI-induced muscarinic cholinergic receptor activation may contribute to excitotoxic processes. In experiment I, regional and temporal changes in calpain-mediated alpha-spectrin degradation were evaluated at 3, 12, 24, and 48 h using immunostaining for 145-kDa SBDP. Immunostaining of SBDP-145 was only evident in the hemisphere ipsilateral to TBI and was generally limited to the cortex except at 24 h when immunostaining was also prominent in the dentate gyrus and striatum. In Experiment II, cerebral spinal fluid (CSF) samples were analyzed for various SBDPs 24 h after moderate lateral fluid percussion TBI. Rats were administered either dicyclomine (5 mg/kg i.p.) or saline vehicle (n = 8 per group) 5 min prior to injury. Injury produced significant increases (p < 0.001) of 300%, 230%, and >1000% in SBDP-150, -145, and -120, respectively in vehicle-treated rats compared to sham. Dicyclomine treatment produced decreases of 38% (p = 0.077), 37% (p = 0.028), and 63% (p = 0.051) in SBDP-150, -145, and -120, respectively, compared to vehicle-treated injury. Following CSF extraction, coronal brain sections were processed for detecting degenerating neurons using Fluoro-Jade histofluorescence. Stereological techniques were used to quantify neuronal degeneration in the dorsal hippocampus CA2/3 region and in the parietal cortex. No significant differences were detected in numbers of degenerating neurons in the dorsal CA2/3 hippocampus or the parietal cortex between saline and dicyclomine treatment groups. The percent weight loss following TBI was significantly reduced by dicyclomine treatment. These data provide additional evidence that, as TBI biomarkers, SBDPs are able to detect a therapeutic intervention even in the absence of changes in neuronal cell degeneration measured by Fluoro-jade.
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Affiliation(s)
- Christopher D. Cox
- Department of Neurological Surgery, University of California at Davis, Davis, California
| | - Eric J. West
- Department of Neurological Surgery, University of California at Davis, Davis, California
| | | | - Kevin K.W. Wang
- Banyan Biomarkers, Inc., Alachua, Florida
- Departments of Psychiatry and Anesthesiology, University of Florida, Gainesville, Florida
| | - Ronald L. Hayes
- Banyan Biomarkers, Inc., Alachua, Florida
- Departments of Psychiatry and Anesthesiology, University of Florida, Gainesville, Florida
| | - Bruce G. Lyeth
- Department of Neurological Surgery, University of California at Davis, Davis, California
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39
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Calpain-mediated signaling mechanisms in neuronal injury and neurodegeneration. Mol Neurobiol 2008; 38:78-100. [PMID: 18686046 DOI: 10.1007/s12035-008-8036-x] [Citation(s) in RCA: 275] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Accepted: 07/17/2008] [Indexed: 12/19/2022]
Abstract
Calpain is a ubiquitous calcium-sensitive protease that is essential for normal physiologic neuronal function. However, alterations in calcium homeostasis lead to persistent, pathologic activation of calpain in a number of neurodegenerative diseases. Pathologic activation of calpain results in the cleavage of a number of neuronal substrates that negatively affect neuronal structure and function, leading to inhibition of essential neuronal survival mechanisms. In this review, we examine the mechanistic underpinnings of calcium dysregulation resulting in calpain activation in the acute neurodegenerative diseases such as cerebral ischemia and in the chronic neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, prion-related encephalopathy, and amylotrophic lateral sclerosis. The premise of this paper is that analysis of the signaling and transcriptional consequences of calpain-mediated cleavage of its various substrates for any neurodegenerative disease can be extrapolated to all of the neurodegenerative diseases vulnerable to calcium dysregulation.
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40
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Gendron TF, McCartney S, Causevic E, Ko LW, Yen SH. Ethanol enhances tau accumulation in neuroblastoma cells that inducibly express tau. Neurosci Lett 2008; 443:67-71. [PMID: 18672021 DOI: 10.1016/j.neulet.2008.07.052] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 07/11/2008] [Accepted: 07/21/2008] [Indexed: 11/25/2022]
Abstract
Chronic alcohol consumption causes pathological changes in the brain and neuronal loss. Ethanol toxicity may partially result from the perturbation of microtubule-associated proteins, like tau. Tau dysfunction is well known for its involvement in certain neurodegenerative diseases, such as Alzheimer's disease. In the present study, the effect of ethanol on tau was examined using differentiated human neuroblastoma cells that inducibly express the 4R0N isoform of tau via a tetracycline-off expression system. During tau induction, ethanol exposure (1.25-5mg/ml) dose-dependently increased tau protein levels and reduced cell viability. The increase in cell death likely resulted from tau accumulation since increased levels of tau were sufficient to reduce cell viability and ethanol was toxic to cells expressing tau but not to non-induced controls. Tau accumulation did not result from greater tetracycline-off induction since ethanol increased neither tau mRNA expression nor the expression of the tetracycline-controlled transactivator. Additionally, ethanol increased endogenous tau protein levels in neuroblastoma cells lacking the tetracycline-off induction system for tau. Ethanol delayed tau clearance suggesting ethanol impedes its degradation. Though ethanol inhibited neither cathepsin B, cathepsin D, nor chymotrypsin-like activity, it did significantly reduce calpain I expression and activity. Calpain I knockdown by shRNA increased tau levels indicating that calpain participates in tau degradation in this model. Moreover, the activation of calpain, by the calcium ionophore A23187, partially reversed the accumulation of tau resulting from ethanol exposure. Impaired calpain-mediated degradation may thus contribute to the increased accumulation of tau caused by ethanol.
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Affiliation(s)
- Tania F Gendron
- Department of Neuroscience, Mayo Clinic College of Medicine, Jacksonville, FL 32224, USA
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41
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Rodríguez-Navarro JA, Gómez A, Rodal I, Perucho J, Martinez A, Furió V, Ampuero I, Casarejos MJ, Solano RM, de Yébenes JG, Mena MA. Parkin deletion causes cerebral and systemic amyloidosis in human mutated tau over-expressing mice. Hum Mol Genet 2008; 17:3128-43. [PMID: 18640988 DOI: 10.1093/hmg/ddn210] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Deposition of proteins leading to amyloid takes place in some neurodegenerative diseases such as Alzheimer's disease and Huntington's disease. Mutations of tau and parkin proteins produce neurofibrillary abnormalities without deposition of amyloid. Here we report that mature, parkin null, over-expressing human mutated tau (PK(-/-)/Tau(VLW)) mice have altered behaviour and dopamine neurotransmission, tau pathology in brain and amyloid deposition in brain and peripheral organs. PK(-/-)/Tau(VLW) mice have abnormal behaviour and severe drop out of dopamine neurons in the ventral midbrain, up to 70%, at 12 months and abundant phosphorylated tau positive neuritic plaques, neuro-fibrillary tangles, astrogliosis, microgliosis and plaques of murine beta-amyloid in the hippocampus. PK(-/-)/Tau(VLW) mice have organomegaly of the liver, spleen and kidneys. The electron microscopy of the liver confirmed the presence of a fibrillary protein deposits with amyloid characteristics. There is also accumulation of mouse tau in hepatocytes. These mice have lower levels of CHIP-HSP70, involved in the proteosomal degradation of tau, increased oxidative stress, measured as depletion of glutathione which, added to lack of parkin, could trigger tau accumulation and amyloidogenesis. This model is the first that demonstrates beta-amyloid deposits caused by over-expression of tau and without modification of the amyloid precursor protein, presenilins or secretases. PK(-/-)/Tau(VLW) mice provide a link between the two proteins more important for the pathogenesis of Alzheimer disease.
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42
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Singer D, Herth N, Kuhlmann J, Holland-Nell K, Beck-Sickinger A, Hoffmann R. Mapping of phosphorylation-dependent anti-tau monoclonal antibodies in immunoblots using human tau-constructs synthesized by native chemical ligation. Biochem Biophys Res Commun 2008; 367:318-22. [DOI: 10.1016/j.bbrc.2007.12.109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Accepted: 12/14/2007] [Indexed: 11/28/2022]
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43
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Tie L, Xu Y, Lin YH, Yao XH, Wu HL, Li YH, Shen ZF, Yu HM, Li XJ. Down-Regulation of Brain-Pancreas Relative Protein in Diabetic Rats and by High Glucose in PC12 Cells: Prevention by Calpain Inhibitors. J Pharmacol Sci 2008; 106:28-37. [DOI: 10.1254/jphs.fp0071092] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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44
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Mansouri B, Henne WM, Oomman SK, Bliss R, Attridge J, Finckbone V, Zeitouni T, Hoffman T, Bahr BA, Strahlendorf HK, Strahlendorf JC. Involvement of calpain in AMPA-induced toxicity to rat cerebellar Purkinje neurons. Eur J Pharmacol 2006; 557:106-14. [PMID: 17188264 DOI: 10.1016/j.ejphar.2006.11.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 11/09/2006] [Accepted: 11/13/2006] [Indexed: 02/06/2023]
Abstract
AMPA receptor-elicited excitotoxicity is manifested as both a type of programmed cell death termed dark cell degeneration and edematous necrosis, both of which are linked to increased intracellular Ca2+ concentration. The appearance of marked cytoskeletal changes in response to abusive AMPA receptor activation, coupled with increased intracellular Ca2+ concentration suggests activation of various destructive enzymes such as calpains, a family of Ca2+-dependent cysteine proteases. Since calpains and AMPA have been linked to both necrotic cell death and programmed cell death, we sought to determine the role of calpains in mediating both types of AMPA-mediated toxicity in Purkinje neurons of the cerebellum. These studies employed immunohistochemistry for cytoskeletal breakdown products of calpain activity coupled with confocal microscopy and pharmacological interventions with calpain and AMPA receptor antagonists. The present study identifies an early involvement of calpains in mediating AMPA-induced dark cell degeneration, but not edematous necrosis, based upon the effectiveness of AMPA to generate calpain-derived alpha-spectrin cleavage products in cerebellar Purkinje neurons that express dark cell degeneration, and the effectiveness of calpain antagonists, PD150606 and MDL28170, to attenuate AMPA-induced dark cell degeneration. Moreover, the AMPA receptor antagonist CNQX, a proven inhibitor of AMPA-elicited dark cell degeneration, also blocked AMPA-induced increases in alpha-spectrin, further suggesting interplay between abusive AMPA receptor activation, calpain activation and dark cell degeneration. Since AMPA-induced dark cell degeneration possesses morphological changes that resemble those that occur following brain ischemia in vivo, hypoglycemia, or extended seizure episodes, the involvement of calpains as mediators of cell death is potentially far reaching and has widespread therapeutic implications in numerous CNS disorders.
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Affiliation(s)
- Bobbak Mansouri
- Department of Physiology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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45
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Chen Q, Wang S, Thompson SN, Hall ED, Guttmann RP. Identification and characterization of PEBP as a calpain substrate. J Neurochem 2006; 99:1133-41. [PMID: 17018026 DOI: 10.1111/j.1471-4159.2006.04160.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Calpains are calcium- and thiol-dependent proteases whose dysregulation has been implicated in a number of diseases and conditions such as cardiovascular dysfunction, ischemic stroke, and Alzheimer's disease (AD). While the effects of calpain activity are evident, the precise mechanism(s) by which dysregulated calpain activity results in cellular degeneration are less clear. In order to determine the impact of calpain activity, there is a need to identify the range of specific calpain substrates. Using an in vitro proteomics approach we confirmed that phosphatidylethanolamine-binding protein (PEBP) as a novel in vitro and in situ calpain substrate. We also observed PEBP proteolysis in a model of brain injury in which calpain is clearly activated. In addition, with evidence of calpain dysregulation in AD, we quantitated protein levels of PEBP in postmortem brain samples from the hippocampus of AD and age-matched controls and found that PEBP levels were approximately 20% greater in AD. Finally, with previous evidence that PEBP may act as a serine protease inhibitor, we tested PEBP as an inhibitor of the proteasome and found that PEBP inhibited the chymostrypsin-like activity of the proteasome by approximately 30%. Together these data identify PEBP as a potential in vivo calpain substrate and indicate that increased PEBP levels may contribute to impaired proteasome function.
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Affiliation(s)
- Qinghua Chen
- Department of Gerontology, University of Kentucky, Lexington, Kentucky 40536, USA
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46
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Volke D, Hoffmann R. Purification of bovine Tau versions by affinity chromatography. Protein Expr Purif 2006; 50:37-42. [PMID: 16750637 DOI: 10.1016/j.pep.2006.04.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Accepted: 04/24/2006] [Indexed: 10/24/2022]
Abstract
The nervous-system-specific microtubule-associated Tau proteins promote microtubule stability and assembly. Tau is transiently phosphorylated at about 30 positions and additionally O- and N-glycosylated. Bovine Tau was prepared from a calf brain and purified by affinity chromatography using immobilized monoclonal antibody (mAb) BT-2, which recognizes all Tau-splicing isoforms. Tau was obtained in high purities well above 90% containing even highly phosphorylated Tau versions with isoelectric points below pH 5 without discrimination. Moreover, these highly phosphorylated versions were detected only after purification. The purification progress and the final purity were studied by two-dimensional gel electrophoresis (2DE) using both protein and phosphoprotein stains as well as immunoblots.
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Affiliation(s)
- Daniela Volke
- Bioanalytics, Center for Biotechnology and Biomedicine (BBZ), Faculty of Chemistry and Mineralogy, University of Leipzig, Deutscher Platz 5, 04103 Leipzig, Germany
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47
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Singer D, Lehmann J, Hanisch K, Härtig W, Hoffmann R. Neighbored phosphorylation sites as PHF-tau specific markers in Alzheimer’s disease. Biochem Biophys Res Commun 2006; 346:819-28. [PMID: 16781671 DOI: 10.1016/j.bbrc.2006.05.201] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Accepted: 05/29/2006] [Indexed: 11/23/2022]
Abstract
Neurofibrillary tangles, which represent a major pathological hallmark in Alzheimer's disease (AD), are deposits of the hyperphosphorylated microtubule-associated tau protein (PHF-tau). However, a link between the phosphorylation pattern and the cause or the progress of AD is still missing. The work reported here focused on PHF-tau specific local phosphorylation patterns at Thr212/Ser214 and Thr231/Ser235 using monoclonal antibodies (mAb) generated against correspondingly modified peptides. The binding motifs of the obtained six mAbs were characterized with non-, mono-, and double-phosphorylated peptides as well as terminally shortened sequences. Five mAbs stained neurofibrillary tangles, neuritic plaques, and neuropil threads from autoptic brains of AD cases. Four mAbs recognized PHF-tau without significant cross-reactivity towards normal human tau, bovine tau, and dephosphorylated PHF-tau in ELISA and Western blot analysis. Thus, double phosphorylation is sufficient to distinguish PHF-tau from all other tau versions and there is no need to postulate any PHF-tau specific conformation for this region.
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Affiliation(s)
- David Singer
- Bioanalytics, Center for Biotechnology and Biomedicine (BBZ), Faculty of Chemistry and Mineralogy, University of Leipzig, Deutscher Platz 5, 04103 Leipzig, Germany
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Oka T, Tamada Y, Nakajima E, Shearer TR, Azuma M. Presence of calpain-induced proteolysis in retinal degeneration and dysfunction in a rat model of acute ocular hypertension. J Neurosci Res 2006; 83:1342-51. [PMID: 16528750 DOI: 10.1002/jnr.20827] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The purpose of this study was to determine if calpain-induced proteolysis was associated with retinal degeneration or dysfunction in the rat acute ocular hypertensive model. Acute glaucoma was produced by elevation of IOP to 120 mm Hg for 1 hr. Retinal degeneration was evaluated by H&E staining and apoptosis was determined by TUNEL staining in histologic sections of retina. Electroretinogram (ERG) was carried out to evaluate changes in functionality. Activation of calpains was determined by casein zymography and immunoblotting. Total calcium in retina was measured by atomic absorption spectrophotometry. Proteolysis of alpha-spectrin, tau, cdk5, and p35 (a regulator of cdk5) were evaluated by immunoblotting. The thickness of inner plexiform layer (IPL) and inner nuclear layer (INL), and the number of cells in the ganglion cell layer (GCL) decreased after ocular hypertension. Numerous cells in the INL stained positive for TUNEL and some cells in the outer nuclear layer (ONL) showed TUNEL staining. The a-wave in ERG was temporarily decreased after ocular hypertension and then recovered to normal. In contrast, the b-wave was completely lost. Calpains were activated after ocular hypertension. Activation of calpains was associated with increased calcium in retina. Calpain-dependent proteolysis of alpha-spectrin, tau, and p35 were observed in retina after ocular hypertension. The results suggested that increased calcium and subsequent proteolysis by activated calpains was associated with the death of inner retinal cells due to acute ocular hypertension in the rat model. Calpain inhibitors may be candidate drugs for treatment of retinal degeneration and dysfunction resulting from glaucoma.
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Affiliation(s)
- Takayuki Oka
- Kobe Creative Center, Senju Pharmaceutical Co., Ltd., Kobe, Hyogo, Japan
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Wang YP, Wang XC, Tian Q, Yang Y, Zhang Q, Zhang JY, Zhang YC, Wang ZF, Wang Q, Li H, Wang JZ. Endogenous overproduction of β-amyloid induces tau hyperphosphorylation and decreases the solubility of tau in N2a cells. J Neural Transm (Vienna) 2006; 113:1723-32. [PMID: 16752046 DOI: 10.1007/s00702-006-0507-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Accepted: 04/13/2006] [Indexed: 10/24/2022]
Abstract
Although neurofibrillary tangles and senile plaques have been identified as the hallmark pathological changes in the brain of Alzheimer's disease (AD), the relationship between them is still not fully understood. In the present study, we have studied the effect of endogenously overproduced amyloid beta (A beta) on tau by using wild type amyloid precursor protein (APP) transfected (N2a/APP695), or Swedish mutant APP plus Delta 9 deleted presenilin-1 co-transfected (N2a/APPswe.Delta 9) and APP vector transfected (N2a/vector) cell lines. We measured the secreted and intracellular A beta, including A beta(1-40) and A beta(1-42), by Sandwich ELISA assay. It was shown that the levels of A beta were increased time-dependently in N2a/APP695 and N2a/APPswe.Delta 9 but not in N2a/vector upon butyric acid (BA) treatment. Compared with N2a/vector cells, tau in N2a/APP695 and N2a/APPswe.Delta 9 cells was not extracted by RIPA buffer, and the SDS-extracted tau protein was hyperphosphorylated at Tau-1 and PHF-1 epitopes upon BA treatment. Obvious accumulation of the hyperphosphorylated tau in N2a/APP695 and N2a/APPswe.Delta 9 cells was observed at 48 h after BA treatment. The total level of the extracted tau was reduced in N2a/APP695 and N2a/APPswe.Delta 9 lines compared with N2a/vector cells by Western blot, and this reduction of total tau was also detected by immunofluorescence staining. No obvious alteration of tau mRNA was observed in both N2a/APP695 and N2a/APPswe.Delta 9 cells compared with N2a/vector. This study provides direct evidence demonstrating that endogenously overproduced A beta not only induces tau hyperphosphorylation but also decreases the level and solubility of tau in N2a cell lines.
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Affiliation(s)
- Y-P Wang
- Pathophysiology Department, Huazhong University of Science and Technical, Wuhan, China
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Avila J. Tau phosphorylation and aggregation in Alzheimer's disease pathology. FEBS Lett 2006; 580:2922-7. [PMID: 16529745 DOI: 10.1016/j.febslet.2006.02.067] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Revised: 02/22/2006] [Accepted: 02/25/2006] [Indexed: 12/22/2022]
Abstract
In this article I shall review how tau phosphorylation and aggregation participates in Alzheimer's disease (AD) and other tauopathies. Tau, a microtubule associated protein, is the main component, in phosphorylated form, of the aberrant paired helical filaments found in AD. Tau is present in phosphorylated and aggregated form not only in AD, but in other pathologies (tauopathies). In this review, the phosphorylation of tau, its aggregation, and the possible relation between tau phosphorylation and aggregation is, briefly, described. Also, it is discussed the toxicity of modified tau. In addition, I propose a working model detailing the progression of tau pathologies.
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Affiliation(s)
- Jesús Avila
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Cantoblanco, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
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