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Wong H, Levenga J, Cain P, Rothermel B, Klann E, Hoeffer C. RCAN1 overexpression promotes age-dependent mitochondrial dysregulation related to neurodegeneration in Alzheimer's disease. Acta Neuropathol 2015; 130:829-43. [PMID: 26497675 DOI: 10.1007/s00401-015-1499-8] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Revised: 10/15/2015] [Accepted: 10/16/2015] [Indexed: 10/22/2022]
Abstract
Aging is the largest risk factor for Alzheimer's disease (AD). Patients with Down syndrome (DS) develop symptoms consistent with early-onset AD, suggesting that overexpression of chromosome 21 genes such as Regulator of Calcineurin 1 (RCAN1) plays a role in AD pathogenesis. RCAN1 levels are increased in the brain of DS and AD patients but also in the human brain with normal aging. RCAN1 has been implicated in several neuronal functions, but whether its increased expression is correlative or causal in the aging-related progression of AD remains elusive. We show that brain-specific overexpression of the human RCAN1.1S isoform in mice promotes early age-dependent memory and synaptic plasticity deficits, tau pathology, and dysregulation of dynamin-related protein 1 (DRP1) activity associated with mitochondrial dysfunction and oxidative stress, reproducing key AD features. Based on these findings, we propose that chronic RCAN1 overexpression during aging alters DRP1-mediated mitochondrial fission and thus acts to promote AD-related progressive neurodegeneration.
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Affiliation(s)
- Helen Wong
- Center for Neural Science, New York University, New York, NY, USA
| | - Josien Levenga
- Department of Integrated of Physiology, Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA
| | - Peter Cain
- Department of Integrated of Physiology, Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA
| | - Beverly Rothermel
- Department of Cardiology, University of Texas-Southwestern, Dallas, TX, USA
| | - Eric Klann
- Center for Neural Science, New York University, New York, NY, USA
| | - Charles Hoeffer
- Department of Integrated of Physiology, Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA.
- New York University School of Medicine, New York, NY, USA.
- Linda Crnic Institute, Denver, CO, USA.
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Yamada K, Patel TK, Hochgräfe K, Mahan TE, Jiang H, Stewart FR, Mandelkow EM, Holtzman DM. Analysis of in vivo turnover of tau in a mouse model of tauopathy. Mol Neurodegener 2015; 10:55. [PMID: 26502977 PMCID: PMC4621881 DOI: 10.1186/s13024-015-0052-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 10/21/2015] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Intracellular accumulation of tau as neurofibrillary tangles (NFTs) is the hallmark of Alzheimer's disease (AD) as well as in other tauopathies. Tau is present not only in the cytoplasm but also in the extracellular space such as cerebrospinal fluid (CSF) and brain interstitial fluid (ISF). Although clearance is one critical parameter leading to such intracellular/extracellular tau accumulation, in vivo turnover of tau has not been well characterized. The current study has attempted to precisely determine in vivo turnover rates of tau utilizing tet-off regulatable mice. In particular, we assessed intracellular tau and extracellular tau, soluble tau, insoluble tau and phosphorylated tau at certain sites utilizing a combination of in vivo microdialysis, biochemical analysis and specific ELISAs recognizing each species. To examine the effect of a tauopathy-associated mutation on tau clearance, half-lives of various tau species were compared between the mice with a FTDP-17 mutation that induces β-sheet formation, ΔK280 mutation (pro-aggregant mice) and control mice with additional β-sheet breaking mutations (anti-aggregant mice). RESULTS Here we report that tau is metabolized at much slower turnover rates in vivo than in cell culture. We found that insoluble tau in pro-aggregant mice had a significantly slower half-life (t1/2 = ~34.2 days) than soluble tau (t1/2 = ~9.7 days). In contrast, soluble tau phosphorylated in the proline rich region was cleared faster than total soluble tau. When comparing pro-aggregant mice to anti-agregant mice, turnover rates of soluble tau species were not significantly different. CONCLUSIONS The current study provides a comprehensive description of in vivo turnover of various tau species present in mice that express human tau. The turnover rate of soluble tau was not significantly altered between pro-aggregant mice and anti-aggregant mice. This suggests that altered conformation by ΔK280 does not have a major impact on clearance pathways for soluble tau. In contrast, different tau species displayed different half-lives. Turnover was significantly delayed for insoluble tau whereas it was accelerated for soluble tau phosphorylated in the proline rich region. These differences in susceptibilities to clearance suggest that aggregation and phosphorylation influences tau clearance which may be important in tau pathogenesis.
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Affiliation(s)
- Kaoru Yamada
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan.
| | - Tirth K Patel
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
| | - Katja Hochgräfe
- MPI for Neurological Research, Hamburg Outstation, c/o DESY, Notkestr. 85, 22607, Hamburg, Germany.
| | - Thomas E Mahan
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
| | - Hong Jiang
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
| | - Floy R Stewart
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
| | - Eva-Maria Mandelkow
- MPI for Neurological Research, Hamburg Outstation, c/o DESY, Notkestr. 85, 22607, Hamburg, Germany. .,DZNE (German Ctr Neurodegen. Diseases), Ludwig-Erhard-Allee 2, 53175, Bonn, Germany. .,CAESAR Research Center, Ludwig-Erhard-Allee 2, 53175, Bonn, Germany.
| | - David M Holtzman
- Department of Neurology, Hope Center for Neurological Disorders, Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
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BAG2 expression dictates a functional intracellular switch between the p38-dependent effects of nicotine on tau phosphorylation levels via the α7 nicotinic receptor. Exp Neurol 2015; 275 Pt 1:69-77. [PMID: 26496817 DOI: 10.1016/j.expneurol.2015.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/25/2015] [Accepted: 10/19/2015] [Indexed: 01/03/2023]
Abstract
The histopathological hallmarks present in Alzheimer's disease (AD) brain are plaques of Aβ peptide, neurofibrillary tangles of hyperphosphorylated tau protein, and a reduction in nicotinic acetylcholine receptor (nAChR) levels. The role of nAChRs in AD is particularly controversial. Tau protein function is regulated by phosphorylation, and its hyperphosphorylated forms are significantly more abundant in AD brain. Little is known about the relationship between nAChR and phospho-tau degradation machinery. Activation of nAChRs has been reported to increase and decrease tau phosphorylation levels, and the mechanisms responsible for this discrepancy are not presently understood. The co-chaperone BAG2 is capable of regulating phospho-tau levels via protein degradation. In SH-SY5Y cell line and rat primary hippocampal cell culture low endogenous BAG2 levels constitute an intracellular environment conducive to nicotine-induced accumulation of phosphorylated tau protein. Further, nicotine treatment inhibited endogenous expression of BAG2, resulting in increased levels of phosphorylated tau indistinguishable from those induced by BAG2 knockdown. Conversely, overexpression of BAG2 is conducive to a nicotine-induced reduction in cellular levels of phosphorylated tau protein. In both cases the effect of nicotine was p38MAPK-dependent, while the α7 antagonist MLA was synthetic to nicotine treatment, either increasing levels of phospho-Tau in the absence of BAG2, or further decreasing the levels of phospho-Tau in the presence of BAG2. Taken together, these findings reconcile the apparently contradictory effects of nicotine on tau phosphorylation by suggesting a role for BAG2 as an important regulator of p38-dependent tau kinase activity and phospho-tau degradation in response to nicotinic receptor stimulation. Thus, we report that BAG2 expression dictates a functional intracellular switch between the p38-dependent functions of nicotine on tau phosphorylation levels via the α7 nicotinic receptor.
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Carrettiero DC, Santiago FE, Motzko-Soares ACP, Almeida MC. Temperature and toxic Tau in Alzheimer's disease: new insights. Temperature (Austin) 2015; 2:491-8. [PMID: 27227069 PMCID: PMC4843920 DOI: 10.1080/23328940.2015.1096438] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 09/15/2015] [Accepted: 09/15/2015] [Indexed: 12/31/2022] Open
Abstract
Alzheimer's disease (AD), the most common dementia in the elderly, is characterized by cognitive impairment and severe autonomic symptoms such as disturbance in core body temperature (Tc), which may be predictors or early events in AD onset. Inclusions of phosphorylated Tau (p-Tau) are a hallmark of AD and other neurodegenerative disorders called “Tauopathies.” Animal and human studies show that anesthesia augments p-Tau levels through reduction of Tc, with implications for AD. Additionally, hypothermia impairs memory and cognitive function. The molecular networks related to Tc that are associated with AD remain poorly characterized. Under physiological conditions, Tau binds microtubules, promoting their assembly and stability. The dynamically regulated Tau-microtubule interaction plays an important role in structural remodeling of the cytoskeleton, having important functions in neuronal plasticity and memory in the hippocampus. Hypothermia-induced increases in p-Tau levels are significant, with an 80% increase for each degree Celsius below normothermic conditions. Although the effects of temperature on Tau phosphorylation are evident, its effects on p-Tau degradation remain poorly understoodWe review information concerning the mechanisms of Tau regulation of neuron plasticity via its effects on microtubule dynamics, with focus on pathways regulating the abundance of phosphorylated Tau species. We highlight the effects of temperature on molecular mechanisms influencing the development of Tau-related diseases. Specifically, we argue that cold might preferentially affects central nervous system structures that are highly reliant upon plasticity, such as the hippocampus, and that the effect of cold on Tau phosphorylation may constitute a pathology-initiating trigger leading to neurodegeneration.
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Affiliation(s)
- Daniel Carneiro Carrettiero
- Graduate Program in Neuroscience and Cognition; Universidade Federal do ABC; São Bernardo do Campo, Brasil; Center for Natural Sciences and Humanities; Universidade Federal do ABC; São Bernardo do Campo, Brasil
| | - Fernando Enrique Santiago
- Graduate Program in Neuroscience and Cognition; Universidade Federal do ABC; São Bernardo do Campo , Brasil
| | | | - Maria Camila Almeida
- Graduate Program in Neuroscience and Cognition; Universidade Federal do ABC; São Bernardo do Campo, Brasil; Center for Natural Sciences and Humanities; Universidade Federal do ABC; São Bernardo do Campo, Brasil
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de Paula CAD, Santiago FE, de Oliveira ASA, Oliveira FA, Almeida MC, Carrettiero DC. The Co-chaperone BAG2 Mediates Cold-Induced Accumulation of Phosphorylated Tau in SH-SY5Y Cells. Cell Mol Neurobiol 2015. [DOI: 10.1007/s10571-015-0239-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Abstract
SIGNIFICANCE A constant accumulation of oxidized proteins takes place during aging. Oxidation of proteins leads to a partial unfolding and, therefore, to aggregation. Protein aggregates impair the activity of cellular proteolytic systems (proteasomes, lysosomes), resulting in further accumulation of oxidized proteins. In addition, the accumulation of highly crosslinked protein aggregates leads to further oxidant formation, damage to macromolecules, and, finally, to apoptotic cell death. Furthermore, protein oxidation seems to play a role in the development of various age-related diseases, for example, neurodegenerative diseases. RECENT ADVANCES The highly oxidized lipofuscin accumulates during aging. Lipofuscin formation might cause impaired lysosomal and proteasomal degradation, metal ion accumulation, increased reactive oxygen species formation, and apoptosis. CRITICAL ISSUES It is still unclear to which extent protein oxidation is involved in the progression of aging and in the development of some age-related diseases. FUTURE DIRECTIONS An extensive knowledge of the effects of protein oxidation on the aging process and its contribution to the development of age-related diseases could enable further strategies to reduce age-related impairments. Strategies aimed at lowering aggregate formation might be a straightforward intervention to reduce age-related malfunctions of organs.
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Affiliation(s)
- Sandra Reeg
- German Institute of Human Nutrition , Nuthetal, Germany
| | - Tilman Grune
- German Institute of Human Nutrition , Nuthetal, Germany
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57
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Weber D, Davies MJ, Grune T. Determination of protein carbonyls in plasma, cell extracts, tissue homogenates, isolated proteins: Focus on sample preparation and derivatization conditions. Redox Biol 2015; 5:367-380. [PMID: 26141921 PMCID: PMC4506980 DOI: 10.1016/j.redox.2015.06.005] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 06/10/2015] [Accepted: 06/10/2015] [Indexed: 12/19/2022] Open
Abstract
Protein oxidation is involved in regulatory physiological events as well as in damage to tissues and is thought to play a key role in the pathophysiology of diseases and in the aging process. Protein-bound carbonyls represent a marker of global protein oxidation, as they are generated by multiple different reactive oxygen species in blood, tissues and cells. Sample preparation and stabilization are key steps in the accurate quantification of oxidation-related products and examination of physiological/pathological processes. This review therefore focuses on the sample preparation processes used in the most relevant methods to detect protein carbonyls after derivatization with 2,4-dinitrophenylhydrazine with an emphasis on measurement in plasma, cells, organ homogenates, isolated proteins and organelles. Sample preparation, derivatization conditions and protein handling are presented for the spectrophotometric and HPLC method as well as for immunoblotting and ELISA. An extensive overview covering these methods in previously published articles is given for researchers who plan to measure protein carbonyls in different samples.
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Affiliation(s)
- Daniela Weber
- Department of Molecular Toxicology, German Institute of Human Nutrition, Potsdam-Rehbruecke, Germany.
| | - Michael J Davies
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Tilman Grune
- Department of Molecular Toxicology, German Institute of Human Nutrition, Potsdam-Rehbruecke, Germany
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The Ambiguous Relationship of Oxidative Stress, Tau Hyperphosphorylation, and Autophagy Dysfunction in Alzheimer's Disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:352723. [PMID: 26171115 PMCID: PMC4485995 DOI: 10.1155/2015/352723] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 03/02/2015] [Accepted: 03/03/2015] [Indexed: 12/30/2022]
Abstract
Alzheimer's disease (AD) is the most common form of dementia. The pathological hallmarks of AD are amyloid plaques [aggregates of amyloid-beta (Aβ)] and neurofibrillary tangles (aggregates of tau). Growing evidence suggests that tau accumulation is pathologically more relevant to the development of neurodegeneration and cognitive decline in AD patients than Aβ plaques. Oxidative stress is a prominent early event in the pathogenesis of AD and is therefore believed to contribute to tau hyperphosphorylation. Several studies have shown that the autophagic pathway in neurons is important under physiological and pathological conditions. Therefore, this pathway plays a crucial role for the degradation of endogenous soluble tau. However, the relationship between oxidative stress, tau protein hyperphosphorylation, autophagy dysregulation, and neuronal cell death in AD remains unclear. Here, we review the latest progress in AD, with a special emphasis on oxidative stress, tau hyperphosphorylation, and autophagy. We also discuss the relationship of these three factors in AD.
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Lloret A, Fuchsberger T, Giraldo E, Viña J. Molecular mechanisms linking amyloid β toxicity and Tau hyperphosphorylation in Alzheimer׳s disease. Free Radic Biol Med 2015; 83:186-91. [PMID: 25746773 DOI: 10.1016/j.freeradbiomed.2015.02.028] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 02/23/2015] [Accepted: 02/24/2015] [Indexed: 12/12/2022]
Abstract
Neurofibrillary tangles (aggregates of cytoskeletal Tau protein) and senile plaques (aggregates mainly formed by amyloid β peptide) are two landmark lesions in Alzheimer׳s disease. Some researchers have proposed tangles, whereas others have proposed plaques, as primary lesions. For a long time, these were thought of as independent mechanisms. However, experimental evidence suggests that both lesions are intimately related. We review here some molecular pathways linking amyloid β and Tau toxicities involving, among others, glycogen synthase kinase 3β, p38, Pin1, cyclin-dependent kinase 5, and regulator of calcineurin 1. Understanding amyloid β and Tau toxicities as part of a common pathophysiological mechanism may help to find molecular targets to prevent or even treat the disease.
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Affiliation(s)
- A Lloret
- Department of Physiology, Faculty of Medicine, University of Valencia and Fundacion Investigacion Hospital Clinico Universitario/INCLIVA, 46010 Valencia, Spain
| | - T Fuchsberger
- Department of Physiology, Faculty of Medicine, University of Valencia and Fundacion Investigacion Hospital Clinico Universitario/INCLIVA, 46010 Valencia, Spain
| | - E Giraldo
- Department of Physiology, Faculty of Medicine, University of Valencia and Fundacion Investigacion Hospital Clinico Universitario/INCLIVA, 46010 Valencia, Spain
| | - J Viña
- Department of Physiology, Faculty of Medicine, University of Valencia and Fundacion Investigacion Hospital Clinico Universitario/INCLIVA, 46010 Valencia, Spain.
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60
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Chen X, Guo C, Kong J. Oxidative stress in neurodegenerative diseases. Neural Regen Res 2015; 7:376-85. [PMID: 25774178 PMCID: PMC4350122 DOI: 10.3969/j.issn.1673-5374.2012.05.009] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Accepted: 11/22/2011] [Indexed: 12/18/2022] Open
Abstract
Reactive oxygen species are constantly produced in aerobic organisms as by-products of normal oxygen metabolism and include free radicals such as superoxide anion (O2−) and hydroxyl radical (OH−), and non-radical hydrogen peroxide (H2O2). The mitochondrial respiratory chain and enzymatic reactions by various enzymes are endogenous sources of reactive oxygen species. Exogenous reactive oxygen species -inducing stressors include ionizing radiation, ultraviolet light, and divergent oxidizing chemicals. At low concentrations, reactive oxygen species serve as an important second messenger in cell signaling; however, at higher concentrations and long-term exposure, reactive oxygen species can damage cellular macromolecules such as DNA, proteins, and lipids, which leads to necrotic and apoptotic cell death. Oxidative stress is a condition of imbalance between reactive oxygen species formation and cellular antioxidant capacity due to enhanced ROS generation and/or dysfunction of the antioxidant system. Biochemical alterations in these macromolecular components can lead to various pathological conditions and human diseases, especially neurodegenerative diseases. Neurodegenerative diseases are morphologically featured by progressive cell loss in specific vulnerable neuronal cells, often associated with cytoskeletal protein aggregates forming inclusions in neurons and/or glial cells. Deposition of abnormal aggregated proteins and disruption of metal ions homeostasis are highly associated with oxidative stress. The main aim of this review is to present as much detailed information as possible that is available on various neurodegenerative disorders and their connection with oxidative stress. A variety of therapeutic strategies designed to address these pathological processes are also described. For the future therapeutic direction, one specific pathway that involves the transcription factor nuclear factor erythroid 2-related factor 2 is receiving considerable attention.
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Affiliation(s)
- Xueping Chen
- Department of Human Anatomy and Cell Science, University of Manitoba, Manitoba, Canada
| | - Chunyan Guo
- Department of Pharmacy, Hebei North University, Zhangjiakou 075000, Hebei Province, China
| | - Jiming Kong
- Department of Human Anatomy and Cell Science, University of Manitoba, Manitoba, Canada
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Fontaine SN, Sabbagh JJ, Baker J, Martinez-Licha CR, Darling A, Dickey CA. Cellular factors modulating the mechanism of tau protein aggregation. Cell Mol Life Sci 2015; 72:1863-79. [PMID: 25666877 DOI: 10.1007/s00018-015-1839-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 12/18/2014] [Accepted: 01/13/2015] [Indexed: 01/12/2023]
Abstract
Pathological accumulation of the microtubule-associated protein tau, in the form of neurofibrillary tangles, is a major hallmark of Alzheimer's disease, the most prevalent neurodegenerative condition worldwide. In addition to Alzheimer's disease, a number of neurodegenerative diseases, called tauopathies, are characterized by the accumulation of aggregated tau in a variety of brain regions. While tau normally plays an important role in stabilizing the microtubule network of the cytoskeleton, its dissociation from microtubules and eventual aggregation into pathological deposits is an area of intense focus for therapeutic development. Here we discuss the known cellular factors that affect tau aggregation, from post-translational modifications to molecular chaperones.
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Affiliation(s)
- Sarah N Fontaine
- Department of Molecular Medicine, College of Medicine, Byrd Alzheimer's Institute, University of South Florida, Tampa, FL, 33613, USA
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Kuznetsov IA, Kuznetsov AV. Can numerical modeling help understand the fate of tau protein in the axon terminal? Comput Methods Biomech Biomed Engin 2015; 19:115-25. [PMID: 25563412 DOI: 10.1080/10255842.2014.994119] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
In this paper, we used mathematical modeling to investigate the fate of tau protein in the axon terminal. We developed a comprehensive model of tau transport that accounts for transport of cytosolic tau by diffusion, diffusion transport of microtubule (MT)-bound tau along the MT lattice, active motor-driven transport of MT-bound tau via slow axonal transport mechanism, and degradation of tau in the axon due to tau's finite half-life. We investigated the effect of different assumptions concerning the fate of tau in the terminal on steady-state transport of tau in the axon. In particular, we studied two possible scenarios: (i) tau is destroyed in the terminal and (ii) there is no tau destruction in the terminal, and to avoid tau accumulation we postulated zero flux of tau at the terminal. We found that the tau concentration and percentage of MT-bound tau are not very sensitive to the assumption concerning the fate of tau in the terminal, but the tau's flux and average velocity of tau transport are very sensitive to this assumption. This suggests that measuring the velocity of tau transport and comparing it with the results of mathematical modeling for different assumptions concerning tau's fate in the terminal can provide information concerning what happens to tau in the terminal.
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Affiliation(s)
- I A Kuznetsov
- a Department of Biomedical Engineering , Johns Hopkins University , Baltimore , MD 21218-2694 , USA
| | - A V Kuznetsov
- b Department of Mechanical and Aerospace Engineering , North Carolina State University , Raleigh , NC 27695-7910 , USA
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63
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Rapid proteasomal degradation of posttranscriptional regulators of the TIS11/tristetraprolin family is induced by an intrinsically unstructured region independently of ubiquitination. Mol Cell Biol 2014; 34:4315-28. [PMID: 25246635 DOI: 10.1128/mcb.00643-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The TIS11/tristetraprolin (TTP) CCCH tandem zinc finger proteins are major effectors in the destabilization of mRNAs bearing AU-rich elements (ARE) in their 3' untranslated regions. In this report, we demonstrate that the Drosophila melanogaster dTIS11 protein is short-lived due to its rapid ubiquitin-independent degradation by the proteasome. Our data indicate that this mechanism is tightly associated with the intrinsically unstructured, disordered N- and C-terminal domains of the protein. Furthermore, we show that TTP, the mammalian TIS11/TTP protein prototype, shares the same three-dimensional characteristics and is degraded by the same proteolytic pathway as dTIS11, thereby indicating that this mechanism has been conserved across evolution. Finally, we observed a phosphorylation-dependent inhibition of dTIS11 and TTP degradation by the proteasome in vitro, raising the possibility that such modifications directly affect proteasomal recognition for these proteins. As a group, RNA-binding proteins (RNA-BPs) have been described as enriched in intrinsically disordered regions, thus raising the possibility that the mechanism that we uncovered for TIS11/TTP turnover is widespread among other RNA-BPs.
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64
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Wu Y, Deng Y, Zhang S, Luo Y, Cai F, Zhang Z, Zhou W, Li T, Song W. Amyloid-β precursor protein facilitates the regulator of calcineurin 1-mediated apoptosis by downregulating proteasome subunit α type-5 and proteasome subunit β type-7. Neurobiol Aging 2014; 36:169-77. [PMID: 25194880 DOI: 10.1016/j.neurobiolaging.2014.07.029] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/23/2014] [Accepted: 07/23/2014] [Indexed: 11/28/2022]
Abstract
Individuals with Down syndrome (DS), caused by trisomy of chromosome 21, inevitably develop characteristic Alzheimer's disease (AD) neuropathology, including neuritic plaques, neurofibrillary tangles, and neuronal loss. Amyloid-β protein, the major component of neuritic plaques, is the proteolytic product of amyloid-β precursor protein (APP). APP and the regulator of calcineurin 1 (RCAN1) genes on chromosome 21 play a pivotal role in promoting plaque formation and neuronal apoptosis. However, the mechanism underlying AD pathogenesis in DS is not well defined. In this study, we demonstrated that APP significantly increased RCAN1 level in both cells and transgenic mice. Overexpression of APP significantly reduced the expression of 2 proteasome subunits, proteasome subunit α type-5 and proteasome subunit β type-7, leading to the inhibition of proteasomal degradation of RCAN1. Furthermore, knockdown of RCAN1 expression attenuated APP-induced neuronal apoptosis. Taken together, the results clearly showed that APP has a previously unknown function in regulating RCAN1-mediated neuronal apoptosis through the proteasome pathway. Our study demonstrates a novel mechanism by which overexpression of APP and RCAN1 causes neurodegeneration and AD pathogenesis in DS, and it provides new insights into the potential of targeting APP-induced proteasomal impairment and RCAN1 accumulation for AD and DS treatment.
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Affiliation(s)
- Yili Wu
- Chongqing City Key Lab of Translational Medical Research in Cognitive Development and Learning and Memory Disorders and Ministry of Education Key Lab of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China; Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Yu Deng
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Shuting Zhang
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Yawen Luo
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Fang Cai
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Zhuohua Zhang
- State Key Laboratory of Medical Genetics of China, Central South University, Changsha, Hunan, China
| | - Weihui Zhou
- Chongqing City Key Lab of Translational Medical Research in Cognitive Development and Learning and Memory Disorders and Ministry of Education Key Lab of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
| | - Tingyu Li
- Chongqing City Key Lab of Translational Medical Research in Cognitive Development and Learning and Memory Disorders and Ministry of Education Key Lab of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China.
| | - Weihong Song
- Chongqing City Key Lab of Translational Medical Research in Cognitive Development and Learning and Memory Disorders and Ministry of Education Key Lab of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China; Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, The University of British Columbia, Vancouver, British Columbia, Canada.
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65
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Functional transcriptome analysis of the postnatal brain of the Ts1Cje mouse model for Down syndrome reveals global disruption of interferon-related molecular networks. BMC Genomics 2014; 15:624. [PMID: 25052193 PMCID: PMC4124147 DOI: 10.1186/1471-2164-15-624] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/16/2014] [Indexed: 12/25/2022] Open
Abstract
Background The Ts1Cje mouse model of Down syndrome (DS) has partial triplication of mouse chromosome 16 (MMU16), which is partially homologous to human chromosome 21. These mice develop various neuropathological features identified in DS individuals. We analysed the effect of partial triplication of the MMU16 segment on global gene expression in the cerebral cortex, cerebellum and hippocampus of Ts1Cje mice at 4 time-points: postnatal day (P)1, P15, P30 and P84. Results Gene expression profiling identified a total of 317 differentially expressed genes (DEGs), selected from various spatiotemporal comparisons, between Ts1Cje and disomic mice. A total of 201 DEGs were identified from the cerebellum, 129 from the hippocampus and 40 from the cerebral cortex. Of these, only 18 DEGs were identified as common to all three brain regions and 15 were located in the triplicated segment. We validated 8 selected DEGs from the cerebral cortex (Brwd1, Donson, Erdr1, Ifnar1, Itgb8, Itsn1, Mrps6 and Tmem50b), 18 DEGs from the cerebellum (Atp5o, Brwd1, Donson, Dopey2, Erdr1, Hmgn1, Ifnar1, Ifnar2, Ifngr2, Itgb8, Itsn1, Mrps6, Paxbp1, Son, Stat1, Tbata, Tmem50b and Wrb) and 11 DEGs from the hippocampus (Atp5o, Brwd1, Cbr1, Donson, Erdr1, Itgb8, Itsn1, Morc3, Son, Tmem50b and Wrb). Functional clustering analysis of the 317 DEGs identified interferon-related signal transduction as the most significantly dysregulated pathway in Ts1Cje postnatal brain development. RT-qPCR and western blotting analysis showed both Ifnar1 and Stat1 were over-expressed in P84 Ts1Cje cerebral cortex and cerebellum as compared to wild type littermates. Conclusions These findings suggest over-expression of interferon receptor may lead to over-stimulation of Jak-Stat signaling pathway which may contribute to the neuropathology in Ts1Cje or DS brain. The role of interferon mediated activation or inhibition of signal transduction including Jak-Stat signaling pathway has been well characterized in various biological processes and disease models including DS but information pertaining to the role of this pathway in the development and function of the Ts1Cje or DS brain remains scarce and warrants further investigation. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-624) contains supplementary material, which is available to authorized users.
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Vergara C, Ordóñez-Gutiérrez L, Wandosell F, Ferrer I, del Río JA, Gavín R. Role of PrP(C) Expression in Tau Protein Levels and Phosphorylation in Alzheimer's Disease Evolution. Mol Neurobiol 2014; 51:1206-20. [PMID: 24965601 DOI: 10.1007/s12035-014-8793-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/15/2014] [Indexed: 10/25/2022]
Abstract
Alzheimer's disease (AD) is characterized by the presence of amyloid plaques mainly consisting of hydrophobic β-amyloid peptide (Aβ) aggregates and neurofibrillary tangles (NFTs) composed principally of hyperphosphorylated tau. Aβ oligomers have been described as the earliest effectors to negatively affect synaptic structure and plasticity in the affected brains, and cellular prion protein (PrP(C)) has been proposed as receptor for these oligomers. The most widely accepted theory holds that the toxic effects of Aβ are upstream of change in tau, a neuronal microtubule-associated protein that promotes the polymerization and stabilization of microtubules. However, tau is considered decisive for the progression of neurodegeneration, and, indeed, tau pathology correlates well with clinical symptoms such as dementia. Different pathways can lead to abnormal phosphorylation, and, as a consequence, tau aggregates into paired helical filaments (PHF) and later on into NFTs. Reported data suggest a regulatory tendency of PrP(C) expression in the development of AD, and a putative relationship between PrP(C) and tau processing is emerging. However, the role of tau/PrP(C) interaction in AD is poorly understood. In this study, we show increased susceptibility to Aβ-derived diffusible ligands (ADDLs) in neuronal primary cultures from PrP(C) knockout mice, compared to wild-type, which correlates with increased tau expression. Moreover, we found increased PrP(C) expression that paralleled with tau at early ages in an AD murine model and in early Braak stages of AD in affected individuals. Taken together, these results suggest a protective role for PrP(C) in AD by downregulating tau expression, and they point to this protein as being crucial in the molecular events that lead to neurodegeneration in AD.
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Affiliation(s)
- C Vergara
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia, Baldiri Reixac 15-21, 08028, Barcelona, Spain
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Höhn A, Jung T, Grune T. Pathophysiological importance of aggregated damaged proteins. Free Radic Biol Med 2014; 71:70-89. [PMID: 24632383 DOI: 10.1016/j.freeradbiomed.2014.02.028] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 02/28/2014] [Accepted: 02/28/2014] [Indexed: 02/06/2023]
Abstract
Reactive oxygen species (ROS) are formed continuously in the organism even under physiological conditions. If the level of ROS in cells exceeds the cellular defense capacity, components such as RNA/DNA, lipids, and proteins are damaged and modified, thus affecting the functionality of organelles as well. Proteins are especially prominent targets of various modifications such as oxidation, glycation, or conjugation with products of lipid peroxidation, leading to the alteration of their biological function, nonspecific interactions, and the production of high-molecular-weight protein aggregates. To ensure the maintenance of cellular functions, two proteolytic systems are responsible for the removal of oxidized and modified proteins, especially the proteasome and organelles, mainly the autophagy-lysosomal systems. Furthermore, increased protein oxidation and oxidation-dependent impairment of proteolytic systems lead to an accumulation of oxidized proteins and finally to the formation of nondegradable protein aggregates. Accordingly, the cellular homeostasis cannot be maintained and the cellular metabolism is negatively affected. Here we address the current knowledge of protein aggregation during oxidative stress, aging, and disease.
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Affiliation(s)
- Annika Höhn
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich-Schiller-University Jena, 07743 Jena, Germany
| | - Tobias Jung
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich-Schiller-University Jena, 07743 Jena, Germany
| | - Tilman Grune
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich-Schiller-University Jena, 07743 Jena, Germany.
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68
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Kuznetsov IA, Kuznetsov AV. A coupled model of fast axonal transport of organelles and slow axonal transport of tau protein. Comput Methods Biomech Biomed Engin 2014; 18:1485-94. [PMID: 24867161 DOI: 10.1080/10255842.2014.920830] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We have developed a model that accounts for the effect of a non-uniform distribution of tau protein along the axon length on fast axonal transport of intracellular organelles. The tau distribution is simulated by using a slow axonal transport model; the numerically predicted tau distributions along the axon length were validated by comparing them with experimentally measured tau distributions reported in the literature. We then developed a fast axonal transport model for organelles that accounts for the reduction of kinesin attachment rate to microtubules by tau. We investigated organelle transport for two situations: (1) a uniform tau distribution and (2) a non-uniform tau distribution predicted by the slow axonal transport model. We found that non-uniform tau distributions observed in healthy axons (an increase in tau concentration towards the axon tip) result in a significant enhancement of organelle transport towards the synapse compared with the uniform tau distribution with the same average amount of tau. This suggests that tau may play the role of being an enhancer of organelle transport.
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Affiliation(s)
- I A Kuznetsov
- a Department of Biomedical Engineering , Johns Hopkins University , Baltimore , MD 21218-2694 , USA
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69
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Kim BM, You MH, Chen CH, Lee S, Hong Y, Hong Y, Kimchi A, Zhou XZ, Lee TH. Death-associated protein kinase 1 has a critical role in aberrant tau protein regulation and function. Cell Death Dis 2014; 5:e1237. [PMID: 24853415 PMCID: PMC4047864 DOI: 10.1038/cddis.2014.216] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 04/03/2014] [Accepted: 04/14/2014] [Indexed: 12/17/2022]
Abstract
The presence of tangles composed of phosphorylated tau is one of the neuropathological hallmarks of Alzheimer's disease (AD). Tau, a microtubule (MT)-associated protein, accumulates in AD potentially as a result of posttranslational modifications, such as hyperphosphorylation and conformational changes. However, it has not been fully understood how tau accumulation and phosphorylation are deregulated. In the present study, we identified a novel role of death-associated protein kinase 1 (DAPK1) in the regulation of the tau protein. We found that hippocampal DAPK1 expression is markedly increased in the brains of AD patients compared with age-matched normal subjects. DAPK1 overexpression increased tau protein stability and phosphorylation at multiple AD-related sites. In contrast, inhibition of DAPK1 by overexpression of a DAPK1 kinase-deficient mutant or by genetic knockout significantly decreased tau protein stability and abolished its phosphorylation in cell cultures and in mice. Mechanistically, DAPK1-enhanced tau protein stability was mediated by Ser71 phosphorylation of Pin1, a prolyl isomerase known to regulate tau protein stability, phosphorylation, and tau-related pathologies. In addition, inhibition of DAPK1 kinase activity significantly increased the assembly of MTs and accelerated nerve growth factor-mediated neurite outgrowth. Given that DAPK1 has been genetically linked to late onset AD, these results suggest that DAPK1 is a novel regulator of tau protein abundance, and that DAPK1 upregulation might contribute to tau-related pathologies in AD. Therefore, we offer that DAPK1 might be a novel therapeutic target for treating human AD and other tau-related pathologies.
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Affiliation(s)
- B M Kim
- Division of Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - M-H You
- Division of Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - C-H Chen
- Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - S Lee
- 1] Department of Rehabilitation Science, Graduate School of Inje University, Gimhae, Korea [2] Cardiovascular & Metabolic Disease Center, College of Biomedical Science & Engineering, Inje University, Gimhae, Korea
| | - Y Hong
- 1] Department of Rehabilitation Science, Graduate School of Inje University, Gimhae, Korea [2] Cardiovascular & Metabolic Disease Center, College of Biomedical Science & Engineering, Inje University, Gimhae, Korea
| | - Y Hong
- 1] Division of Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA [2] Department of Rehabilitation Science, Graduate School of Inje University, Gimhae, Korea [3] Cardiovascular & Metabolic Disease Center, College of Biomedical Science & Engineering, Inje University, Gimhae, Korea
| | - A Kimchi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - X Z Zhou
- Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - T H Lee
- Division of Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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Wu Y, Ly PTT, Song W. Aberrant expression of RCAN1 in Alzheimer's pathogenesis: a new molecular mechanism and a novel drug target. Mol Neurobiol 2014; 50:1085-97. [PMID: 24752590 DOI: 10.1007/s12035-014-8704-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 03/31/2014] [Indexed: 01/08/2023]
Abstract
AD, a devastating neurodegenerative disorder, is the most common cause of dementia in the elderly. Patients with AD are characterized by three hallmarks of neuropathology including neuritic plaque deposition, neurofibrillary tangle formation, and neuronal loss. Growing evidences indicate that dysregulation of regulator of calcineurin 1 (RCAN1) plays an important role in the pathogenesis of AD. Aberrant RCAN1 expression facilitates neuronal apoptosis and Tau hyperphosphorylation, leading to neuronal loss and neurofibrillary tangle formation. This review aims to describe the recent advances of the regulation of RCAN1 expression and its physiological functions. Moreover, the AD risk factors-induced RCAN1 dysregulation and its role in promoting neuronal loss, synaptic impairments and neurofibrillary tangle formation are summarized. Furthermore, we provide an outlook into the effects of RCAN1 dysregulation on APP processing, Aβ generation and neuritic plaque formation, and the possible underlying mechanisms, as well as the potential of targeting RCAN1 as a new therapeutic approach.
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Affiliation(s)
- Yili Wu
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, Graduate Program in Neuroscience, The University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, Canada, V6T 1Z3
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71
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Sun X, Wu Y, Herculano B, Song W. RCAN1 overexpression exacerbates calcium overloading-induced neuronal apoptosis. PLoS One 2014; 9:e95471. [PMID: 24751678 PMCID: PMC3994074 DOI: 10.1371/journal.pone.0095471] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 03/26/2014] [Indexed: 01/23/2023] Open
Abstract
Down Syndrome (DS) patients develop characteristic Alzheimer's Disease (AD) neuropathology after their middle age. Prominent neuronal loss has been observed in the cortical regions of AD brains. However, the underlying mechanism leading to this neuronal loss in both DS and AD remains to be elucidated. Calcium overloading and oxidative stress have been implicated in AD pathogenesis. Two major isoforms of regulator of calcineurin 1 (RCAN1), RCAN1.1 and RCAN1.4, are detected in human brains. In this report we defined the transcriptional regulation of RCAN1.1 and RCAN1.4 by two alternative promoters. Calcium overloading upregulated RCAN1.4 expression by activating RCAN1.4 promoter through calcineurin-NFAT signaling pathway, thus forming a negative feedback loop in isoform 4 regulation. Furthermore, RCAN1.4 overexpression exacerbated calcium overloading-induced neuronal apoptosis, which was mediated by caspase-3 apoptotic pathway. Our results suggest that downregulating RCAN1.4 expression in neurons could be beneficial to AD patients.
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Affiliation(s)
- Xiulian Sun
- Qilu Hospital of Shandong University, Jinan, China
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, Graduate Program in Neuroscience, The University of British Columbia, Vancouver, Canada
| | - Yili Wu
- Chongqing City Key Lab of Translational Medical Research in Cognitive Development and Learning and Memory Disorders, and Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, Graduate Program in Neuroscience, The University of British Columbia, Vancouver, Canada
| | - Bruno Herculano
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, Graduate Program in Neuroscience, The University of British Columbia, Vancouver, Canada
| | - Weihong Song
- Chongqing City Key Lab of Translational Medical Research in Cognitive Development and Learning and Memory Disorders, and Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China
- Townsend Family Laboratories, Department of Psychiatry, Brain Research Center, Graduate Program in Neuroscience, The University of British Columbia, Vancouver, Canada
- * E-mail:
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Kamat PK, Rai S, Swarnkar S, Shukla R, Nath C. Molecular and Cellular Mechanism of Okadaic Acid (OKA)-Induced Neurotoxicity: A Novel Tool for Alzheimer’s Disease Therapeutic Application. Mol Neurobiol 2014; 50:852-65. [DOI: 10.1007/s12035-014-8699-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 03/24/2014] [Indexed: 12/31/2022]
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73
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Yamada ES, Respondek G, Müssner S, de Andrade A, Höllerhage M, Depienne C, Rastetter A, Tarze A, Friguet B, Salama M, Champy P, Oertel WH, Höglinger GU. Annonacin, a natural lipophilic mitochondrial complex I inhibitor, increases phosphorylation of tau in the brain of FTDP-17 transgenic mice. Exp Neurol 2014; 253:113-25. [DOI: 10.1016/j.expneurol.2013.12.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 12/12/2013] [Accepted: 12/24/2013] [Indexed: 10/25/2022]
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74
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The proteasome and the degradation of oxidized proteins: Part II - protein oxidation and proteasomal degradation. Redox Biol 2013; 2:99-104. [PMID: 25460724 PMCID: PMC4297946 DOI: 10.1016/j.redox.2013.12.008] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 12/07/2013] [Indexed: 12/17/2022] Open
Abstract
Here, we review the role of oxidative protein modification as a signal for recognition and degradation of proteins. It was clearly demonstrated that the ATP- and ubiquitin-independent 20S proteasome is playing a key role in the selective removal of oxidized proteins. Furthermore, the current knowledge of the substrate susceptibility on the degradation of oxidized proteins and the role of the immunoproteasome will be highlighted.
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75
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Tang C, Welty DF. A dynamic view to the modulation of phosphorylation and O-GlcNAcylation by inhibition of O-GlcNAcase. Comput Biol Chem 2013; 45:9-16. [DOI: 10.1016/j.compbiolchem.2013.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 03/05/2013] [Accepted: 03/11/2013] [Indexed: 12/31/2022]
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76
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Kamat PK, Rai S, Nath C. Okadaic acid induced neurotoxicity: An emerging tool to study Alzheimer's disease pathology. Neurotoxicology 2013; 37:163-72. [DOI: 10.1016/j.neuro.2013.05.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Revised: 04/25/2013] [Accepted: 05/03/2013] [Indexed: 12/18/2022]
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Impact of N-tau on adult hippocampal neurogenesis, anxiety, and memory. Neurobiol Aging 2013; 34:2551-63. [PMID: 23769395 DOI: 10.1016/j.neurobiolaging.2013.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 04/11/2013] [Accepted: 05/08/2013] [Indexed: 01/12/2023]
Abstract
Different pathological tau species are involved in memory loss in Alzheimer's disease, the most common cause of dementia among older people. However, little is known about how tau pathology directly affects adult hippocampal neurogenesis, a unique form of structural plasticity implicated in hippocampus-dependent spatial learning and mood-related behavior. To this aim, we generated a transgenic mouse model conditionally expressing a pathological tau fragment (26-230 aa of the longest human tau isoform, or N-tau) in nestin-positive stem/progenitor cells. We found that N-tau reduced the proliferation of progenitor cells in the adult dentate gyrus, reduced cell survival and increased cell death by a caspase-3-independent mechanism, and recruited microglia. Although the number of terminally differentiated neurons was reduced, these showed an increased dendritic arborization and spine density. This resulted in an increase of anxiety-related behavior and an impairment of episodic-like memory, whereas less complex forms of spatial learning remained unaltered. Understanding how pathological tau species directly affect neurogenesis is important for developing potential therapeutic strategies to direct neurogenic instructive cues for hippocampal function repair.
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Castro JP, Jung T, Grune T, Almeida H. Actin carbonylation: from cell dysfunction to organism disorder. J Proteomics 2013; 92:171-80. [PMID: 23684956 DOI: 10.1016/j.jprot.2013.05.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 12/22/2022]
Abstract
Protein carbonylation is an important event in the context of proteostasis because of its frequency, non-enzymatic nature and irreversible effects. The carbonylation of proteins disturbs their function and leads to protein aggregates, which may precede cellular senescence and cell death. Actin, an evolutionarily conserved cytoskeletal protein that is involved in important cellular processes, is one of the proteins most susceptible to carbonylation. Conditions resulting in oxidative stress are likely to lead to its carbonylation, loss of function and aggregate formation. In this review, we summarise actin susceptibility to carbonylation, as verified in cell free extracts, cell lines and animal models, and review its fate through the activation of cell mechanisms aimed at removing damaged proteins. Their insufficient activity may underlie age-related diseases and the ageing process. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine.
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Affiliation(s)
- José Pedro Castro
- Departamento de Biologia Experimental, Faculdade de Medicina da Universidade do Porto, 4200-319 Porto, Portugal; IBMC-Instituto de Biologia Molecular e Celular, 4150-180 Porto, Portugal; Institute of Nutrition, Friedrich Schiller Universität Jena, Dornburger Str. 24, 07743 Jena, Germany
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Autophagy modulation for Alzheimer's disease therapy. Mol Neurobiol 2013; 48:702-14. [PMID: 23625314 DOI: 10.1007/s12035-013-8457-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 04/09/2013] [Indexed: 01/01/2023]
Abstract
Autophagy is an essential and conserved lysosomal degradation pathway that controls the quality of cytoplasm by eliminating the intracellular aggregated proteins and damaged organelles. Autophagy works in mammalian target of rapamycin (mTOR)-dependent pathway or mTOR-independent pathway to keep the neuronal homeostasis. Mounting evidence has implicated the importance of defective autophagy in the pathogenesis of aging and neurodegenerative diseases, especially in Alzheimer's disease (AD). It has also demonstrated a neuroprotective role of autophagy in mediating the degradation of amyloid beta and tau which are major factors of AD. Amounts of molecules function in either mTOR-dependent pathway or mTOR-independent pathway to induce autophagy, which maybe a potential treatment for AD. In this review, we summarize the latest studies concerning the role of autophagy in AD and explore autophagy modulation as a potential therapeutic strategy for AD. However, to date, little of the researches on autophagy have been performed to investigate the modulation in AD; more investigations need to be confirmed in the future.
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Rodríguez-Martín T, Cuchillo-Ibáñez I, Noble W, Nyenya F, Anderton BH, Hanger DP. Tau phosphorylation affects its axonal transport and degradation. Neurobiol Aging 2013; 34:2146-57. [PMID: 23601672 PMCID: PMC3684773 DOI: 10.1016/j.neurobiolaging.2013.03.015] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 02/15/2013] [Accepted: 03/11/2013] [Indexed: 11/24/2022]
Abstract
Phosphorylated forms of microtubule-associated protein tau accumulate in neurofibrillary tangles in Alzheimer's disease. To investigate the effects of specific phosphorylated tau residues on its function, wild type or phosphomutant tau was expressed in cells. Elevated tau phosphorylation decreased its microtubule binding and bundling, and increased the number of motile tau particles, without affecting axonal transport kinetics. In contrast, reducing tau phosphorylation enhanced the amount of tau bound to microtubules and inhibited axonal transport of tau. To determine whether differential tau clearance is responsible for the increase in phosphomimic tau, we inhibited autophagy in neurons which resulted in a 3-fold accumulation of phosphomimic tau compared with wild type tau, and endogenous tau was unaffected. In autophagy-deficient mouse embryonic fibroblasts, but not in neurons, proteasomal degradation of phosphomutant tau was also reduced compared with wild type tau. Therefore, autophagic and proteasomal pathways are involved in tau degradation, with autophagy appearing to be the primary route for clearing phosphorylated tau in neurons. Defective autophagy might contribute to the accumulaton of tau in neurodegenerative diseases.
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Bushman DM, Chun J. The genomically mosaic brain: aneuploidy and more in neural diversity and disease. Semin Cell Dev Biol 2013; 24:357-69. [PMID: 23466288 PMCID: PMC3637860 DOI: 10.1016/j.semcdb.2013.02.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 01/25/2013] [Accepted: 02/06/2013] [Indexed: 10/27/2022]
Abstract
Genomically identical cells have long been assumed to comprise the human brain, with post-genomic mechanisms giving rise to its enormous diversity, complexity, and disease susceptibility. However, the identification of neural cells containing somatically generated mosaic aneuploidy - loss and/or gain of chromosomes from a euploid complement - and other genomic variations including LINE1 retrotransposons and regional patterns of DNA content variation (DCV), demonstrate that the brain is genomically heterogeneous. The precise phenotypes and functions produced by genomic mosaicism are not well understood, although the effects of constitutive aberrations, as observed in Down syndrome, implicate roles for defined mosaic genomes relevant to cellular survival, differentiation potential, stem cell biology, and brain organization. Here we discuss genomic mosaicism as a feature of the normal brain as well as a possible factor in the weak or complex genetic linkages observed for many of the most common forms of neurological and psychiatric diseases.
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Affiliation(s)
- Diane M. Bushman
- Molecular and Cellular Neuroscience Department, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, California, USA
- Biomedical Sciences Graduate Program, School of Medicine, University of California San Diego, La Jolla, California, USA
| | - Jerold Chun
- Molecular and Cellular Neuroscience Department, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, California, USA
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Hashiguchi M, Hashiguchi T. Kinase–Kinase Interaction and Modulation of Tau Phosphorylation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 300:121-60. [DOI: 10.1016/b978-0-12-405210-9.00004-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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83
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Martin L, Latypova X, Wilson CM, Magnaudeix A, Perrin ML, Terro F. Tau protein phosphatases in Alzheimer's disease: the leading role of PP2A. Ageing Res Rev 2013; 12:39-49. [PMID: 22771380 DOI: 10.1016/j.arr.2012.06.008] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 06/28/2012] [Indexed: 12/21/2022]
Abstract
Tau phosphorylation is regulated by a balance between tau kinase and phosphatase activities. Disruption of this equilibrium was suggested to be at the origin of abnormal tau phosphorylation and thereby that might contributes to tau aggregation. Thus, understanding the regulation modes of tau dephosphorylation is of high interest in determining the possible causes at the origin of the formation of tau aggregates and to elaborate protection strategies to cope with these lesions in AD. Among the possible and relatively specific interventions that reverse tau phosphorylation is the stimulation of certain tau phosphatases. Here, we reviewed tau protein phosphatases, their physiological roles and regulation, their involvement in tau phosphorylation and the relevance to AD. We also reviewed the most common compounds acting on each tau phosphatase including PP2A.
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Affiliation(s)
- Ludovic Martin
- Groupe de Neurobiologie Cellulaire, Homéostasie cellulaire et pathologies, Faculté de Médecine, Limoges, France.
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Abstract
Tau aggregates are present in several neurodegenerative diseases and correlate with the severity of memory deficit in AD (Alzheimer's disease). However, the triggers of tau aggregation and tau-induced neurodegeneration are still elusive. The impairment of protein-degradation systems might play a role in such processes, as these pathways normally keep tau levels at a low level which may prevent aggregation. Some proteases can process tau and thus contribute to tau aggregation by generating amyloidogenic fragments, but the complete clearance of tau mainly relies on the UPS (ubiquitin-proteasome system) and the ALS (autophagy-lysosome system). In the present paper, we focus on the regulation of the degradation of tau by the UPS and ALS and its relation to tau aggregation. We anticipate that stimulation of these two protein-degradation systems might be a potential therapeutic strategy for AD and other tauopathies.
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85
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Abstract
Glucocorticoid (GC) is a major therapeutic agent for the treatment of leukemia because of its ability to induce apoptosis in lymphoid cells. The mechanism causing apoptosis, however, is still controversial. Since the glucocorticoid receptor is a transcription factor, some of its target genes are expected to be implicated in apoptosis. In this study, using a GC-sensitive human pre-B leukemia cell line, Nalm-6, the FK506 binding protein 51 (FKBP5) and regulator of calcineurin 1 (RCAN1) genes were disrupted by homologous recombination, since the expression of both is up-regulated by GC in GC-sensitive but not in GC-resistant leukemic cell lines. While the disruption of FKBP5 had a marginal effect on GC-induced apoptosis, that of RCAN1 resulted in marked resistance to GC. In addition, overexpression of RCAN1 rendered cells more sensitive to DEX. In RCAN1-disrupted cells, levels of some pro-apoptotic and anti-apoptotic Bcl-2 family proteins were decreased and increased, respectively. Finally, phosphorylation of cAMP-response element binding protein (CREB) and up-regulation of CREB target genes by GC were inhibited by RCAN1 disruption, and treatment with a cAMP-inducing agent, forskolin, restored the sensitivity to GC in RCAN1-disrupted Nalm-6 cells. These findings suggest that up-regulation of RCAN1 expression followed by activation of the CREB pathway is required in GC-induced apoptosis.
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Affiliation(s)
- Kazuaki Nagao
- Department of Molecular Genetics, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Japan
| | - Yujiro Iwai
- Department of Molecular Genetics, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Japan
| | - Toshiyuki Miyashita
- Department of Molecular Genetics, Graduate School of Medical Sciences, Kitasato University, Sagamihara, Japan
- * E-mail:
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86
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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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87
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Chondrogianni N, Petropoulos I, Grimm S, Georgila K, Catalgol B, Friguet B, Grune T, Gonos ES. Protein damage, repair and proteolysis. Mol Aspects Med 2012; 35:1-71. [PMID: 23107776 DOI: 10.1016/j.mam.2012.09.001] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 09/26/2012] [Indexed: 01/10/2023]
Abstract
Proteins are continuously affected by various intrinsic and extrinsic factors. Damaged proteins influence several intracellular pathways and result in different disorders and diseases. Aggregation of damaged proteins depends on the balance between their generation and their reversal or elimination by protein repair systems and degradation, respectively. With regard to protein repair, only few repair mechanisms have been evidenced including the reduction of methionine sulfoxide residues by the methionine sulfoxide reductases, the conversion of isoaspartyl residues to L-aspartate by L-isoaspartate methyl transferase and deglycation by phosphorylation of protein-bound fructosamine by fructosamine-3-kinase. Protein degradation is orchestrated by two major proteolytic systems, namely the lysosome and the proteasome. Alteration of the function for both systems has been involved in all aspects of cellular metabolic networks linked to either normal or pathological processes. Given the importance of protein repair and degradation, great effort has recently been made regarding the modulation of these systems in various physiological conditions such as aging, as well as in diseases. Genetic modulation has produced promising results in the area of protein repair enzymes but there are not yet any identified potent inhibitors, and, to our knowledge, only one activating compound has been reported so far. In contrast, different drugs as well as natural compounds that interfere with proteolysis have been identified and/or developed resulting in homeostatic maintenance and/or the delay of disease progression.
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Affiliation(s)
- Niki Chondrogianni
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Helenic Research Foundation, 48 Vas. Constantinou Ave., 116 35 Athens, Greece.
| | - Isabelle Petropoulos
- Laboratoire de Biologie Cellulaire du Vieillissement, UR4-UPMC, IFR 83, Université Pierre et Marie Curie-Paris 6, 4 Place Jussieu, 75005 Paris, France
| | - Stefanie Grimm
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich-Schiller University, Dornburger Straße 24, 07743 Jena, Germany
| | - Konstantina Georgila
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Helenic Research Foundation, 48 Vas. Constantinou Ave., 116 35 Athens, Greece
| | - Betul Catalgol
- Department of Biochemistry, Faculty of Medicine, Genetic and Metabolic Diseases Research Center (GEMHAM), Marmara University, Haydarpasa, Istanbul, Turkey
| | - Bertrand Friguet
- Laboratoire de Biologie Cellulaire du Vieillissement, UR4-UPMC, IFR 83, Université Pierre et Marie Curie-Paris 6, 4 Place Jussieu, 75005 Paris, France
| | - Tilman Grune
- Department of Nutritional Toxicology, Institute of Nutrition, Friedrich-Schiller University, Dornburger Straße 24, 07743 Jena, Germany
| | - Efstathios S Gonos
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Helenic Research Foundation, 48 Vas. Constantinou Ave., 116 35 Athens, Greece.
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88
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Fuster-Matanzo A, Llorens-Martín M, Jurado-Arjona J, Avila J, Hernández F. Tau protein and adult hippocampal neurogenesis. Front Neurosci 2012; 6:104. [PMID: 22787440 PMCID: PMC3391648 DOI: 10.3389/fnins.2012.00104] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 06/21/2012] [Indexed: 12/16/2022] Open
Abstract
Tau protein is a microtubule-associated protein found in the axonal compartment that stabilizes neuronal microtubules under normal physiological conditions. Tau metabolism has attracted much attention because of its role in neurodegenerative disorders called tauopathies, mainly Alzheimer disease. Here, we review recent findings suggesting that axonal outgrowth in subgranular zone during adult hippocampal neurogenesis requires a dynamic microtubule network and tau protein facilitates to maintain that dynamic cytoskeleton. Those functions are carried out in part by tau isoform with only three microtubule-binding domains (without exon 10) and by presence of hyperphosphorylated tau forms. Thus, tau is a good marker and a valuable tool to study new axons in adult neurogenesis.
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Affiliation(s)
- Almudena Fuster-Matanzo
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, (CSIC/UAM) Madrid, Spain
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89
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Van der Jeugd A, Hochgräfe K, Ahmed T, Decker JM, Sydow A, Hofmann A, Wu D, Messing L, Balschun D, D'Hooge R, Mandelkow EM. Cognitive defects are reversible in inducible mice expressing pro-aggregant full-length human Tau. Acta Neuropathol 2012; 123:787-805. [PMID: 22532069 PMCID: PMC4979687 DOI: 10.1007/s00401-012-0987-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 03/20/2012] [Accepted: 04/12/2012] [Indexed: 01/19/2023]
Abstract
Neurofibrillary lesions of abnormal Tau are hallmarks of Alzheimer disease and frontotemporal dementias. Our regulatable (Tet-OFF) mouse models of tauopathy express variants of human full-length Tau in the forebrain (CaMKIIα promoter) either with mutation ΔK280 (pro-aggregant) or ΔK280/I277P/I308P (anti-aggregant). Co-expression of luciferase enables in vivo quantification of gene expression by bioluminescence imaging. Pro-aggregant mice develop synapse loss and Tau-pathology including missorting, phosphorylation and early pretangle formation, whereas anti-aggregant mice do not. We correlated hippocampal Tau pathology with learning/memory performance and synaptic plasticity. Pro-aggregant mice at 16 months of gene expression exhibited severe cognitive deficits in Morris water maze and in passive-avoidance paradigms, whereas anti-aggregant mice were comparable to controls. Cognitive impairment of pro-aggregant mice was accompanied by loss of hippocampal LTP in CA1 and CA3 areas and by a reduction of synaptic proteins and dendritic spines, although no neuronal loss was observed. Remarkably, memory and LTP recovered when pro-aggregant Tau was switched-OFF for ~4 months, Tau phosphorylation and missorting were reversed, and synapses recovered. Moreover, soluble and insoluble pro-aggregant hTau40 disappeared, while insoluble mouse Tau was still present. This study links early Tau pathology without neurofibrillary tangles and neuronal death to cognitive decline and synaptic dysfunction. It demonstrates that Tau-induced impairments are reversible after switching-OFF pro-aggregant Tau. Therefore, our mouse model may mimic an early phase of AD when the hippocampus does not yet suffer from irreversible cell death but cognitive deficits are already striking. It offers potential to evaluate drugs with regard to learning and memory performance.
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Affiliation(s)
- Ann Van der Jeugd
- Laboratory of Biological Psychology, Dept. Psychology, K.U.Leuven, Tiensestraat 102, 3000 Leuven, Belgium
| | - Katja Hochgräfe
- DZNE (German Center for Neurodegenerative Diseases) and CAESAR Research Center, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Tariq Ahmed
- Laboratory of Biological Psychology, Dept. Psychology, K.U.Leuven, Tiensestraat 102, 3000 Leuven, Belgium
| | - Jochen M. Decker
- DZNE (German Center for Neurodegenerative Diseases) and CAESAR Research Center, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Astrid Sydow
- Max-Planck-Institute for Neurological Research, Gleuelerstr. 50, 50931 Cologne, Germany
| | - Anne Hofmann
- Max-Planck-Institute for Neurological Research, Gleuelerstr. 50, 50931 Cologne, Germany
| | - Dan Wu
- DZNE (German Center for Neurodegenerative Diseases) and CAESAR Research Center, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
- Max-Planck-Institute for Neurological Research, Gleuelerstr. 50, 50931 Cologne, Germany
| | - Lars Messing
- DZNE (German Center for Neurodegenerative Diseases) and CAESAR Research Center, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Detlef Balschun
- Laboratory of Biological Psychology, Dept. Psychology, K.U.Leuven, Tiensestraat 102, 3000 Leuven, Belgium
| | - Rudi D'Hooge
- Laboratory of Biological Psychology, Dept. Psychology, K.U.Leuven, Tiensestraat 102, 3000 Leuven, Belgium
| | - Eva-Maria Mandelkow
- DZNE (German Center for Neurodegenerative Diseases) and CAESAR Research Center, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
- Max-Planck-Institute for Neurological Research, Gleuelerstr. 50, 50931 Cologne, Germany
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90
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Valdiglesias V, Fernández-Tajes J, Pásaro E, Méndez J, Laffon B. Identification of differentially expressed genes in SHSY5Y cells exposed to okadaic acid by suppression subtractive hybridization. BMC Genomics 2012; 13:46. [PMID: 22284234 PMCID: PMC3296583 DOI: 10.1186/1471-2164-13-46] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 01/27/2012] [Indexed: 12/02/2022] Open
Abstract
Background Okadaic acid (OA), a toxin produced by several dinoflagellate species is responsible for frequent food poisonings associated to shellfish consumption. Although several studies have documented the OA effects on different processes such as cell transformation, apoptosis, DNA repair or embryogenesis, the molecular mechanistic basis for these and other effects is not completely understood and the number of controversial data on OA is increasing in the literature. Results In this study, we used suppression subtractive hybridization in SHSY5Y cells to identify genes that are differentially expressed after OA exposure for different times (3, 24 and 48 h). A total of 247 subtracted clones which shared high homology with known genes were isolated. Among these, 5 specific genes associated with cytoskeleton and neurotransmission processes (NEFM, TUBB, SEPT7, SYT4 and NPY) were selected to confirm their expression levels by real-time PCR. Significant down-regulation of these genes was obtained at the short term (3 and 24 h OA exposure), excepting for NEFM, but their expression was similar to the controls at 48 h. Conclusions From all the obtained genes, 114 genes were up-regulated and 133 were down-regulated. Based on the NCBI GenBank and Gene Ontology databases, most of these genes are involved in relevant cell functions such as metabolism, transport, translation, signal transduction and cell cycle. After quantitative PCR analysis, the observed underexpression of the selected genes could underlie the previously reported OA-induced cytoskeleton disruption, neurotransmission alterations and in vivo neurotoxic effects. The basal expression levels obtained at 48 h suggested that surviving cells were able to recover from OA-caused gene expression alterations.
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Affiliation(s)
- Vanessa Valdiglesias
- Toxicology Unit, Psychobiology Department, University of A Coruña, Edificio de Servicios Centrales de Investigación, Campus Elviña s/n, 15071 A Coruña, Spain
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91
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Abstract
The ubiquitin-proteasomal system is an essential element of the protein quality control machinery in cells. The central part of this system is the 20S proteasome. The proteasome is a barrel-shaped multienzyme complex, containing several active centers hidden at the inner surface of the hollow cylinder. So, the regulation of the substrate entry toward the inner proteasomal surface is a key control mechanism of the activity of this protease. This chapter outlines the knowledge on the structure of the subunits of the 20S proteasome, the binding and structure of some proteasomal regulators and inducible proteasomal subunits. Therefore, this chapter imparts the knowledge on proteasomal structure which is required for the understanding of the following chapters.
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92
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Proteasome and Neurodegeneratıve Diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 109:397-414. [DOI: 10.1016/b978-0-12-397863-9.00011-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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93
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Iqbal K, Liu F, Gong CX, Grundke-Iqbal I. Tau in Alzheimer disease and related tauopathies. Curr Alzheimer Res 2011; 7:656-64. [PMID: 20678074 DOI: 10.2174/156720510793611592] [Citation(s) in RCA: 676] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 01/20/2010] [Indexed: 01/17/2023]
Abstract
Tau is the major microtubule associated protein (MAP) of a mature neuron. The other two neuronal MAPs are MAP1 and MAP2. An established function of MAPs is their interaction with tubulin and promotion of its assembly into microtubules and stabilization of the microtubule network. The microtubule assembly promoting activity of tau, a phosphoprotein, is regulated by its degree of phosphorylation. Normal adult human brain tau contains 2-3 moles phosphate/mole of tau protein. Hyperphosphorylation of tau depresses this biological activity of tau. In Alzheimer disease (AD) brain tau is ~three to four-fold more hyperphosphorylated than the normal adult brain tau and in this hyperphosphorylated state it is polymerized into paired helical filaments ([PHF) admixed with straight filaments (SF) forming neurofibrillary tangles. Tau is transiently hyperphosphorylated during development and during anesthesia and hypothermia but not to the same state as in AD brain. The abnormally hyperphosphorylated tau in AD brain is distinguished from transiently hyperphosphorylated tau by its ability (1) to sequester normal tau, MAP1 and MAP2 and disrupt microtubules, and (2) to self-assemble into PHF/SF. The cytosolic abnormally hyperphosphorylated tau, because of oligomerization, unlike normal tau, is sedimentable and on self-assembly into PHF/SF, loses its ability to sequester normal MAPs. Some of the tau in AD brain is truncated which also promotes its self-assembly. Tau mutations found in frontotemporal dementia apparently promote its abnormal hyperphosphorylation. Thus, the AD abnormally hyperphosphorylated tau (1) is distinguishable from both normal and transiently hyperphosphorylated taus, and (2) is inhibitory when in a cytosolic/oligomeric state but not when it is self-assembled into PHF/SF. Inhibition of abnormal hyperphosphorylation of tau offers a promising therapeutic target for AD and related tauopathies.
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Affiliation(s)
- K Iqbal
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, 1050 Forest Hill Road, Staten Island, New York 10314-6399, USA.
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94
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Jung MS, Park JH, Ryu YS, Choi SH, Yoon SH, Kwen MY, Oh JY, Song WJ, Chung SH. Regulation of RCAN1 protein activity by Dyrk1A protein-mediated phosphorylation. J Biol Chem 2011; 286:40401-12. [PMID: 21965663 PMCID: PMC3220559 DOI: 10.1074/jbc.m111.253971] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 09/21/2011] [Indexed: 01/22/2023] Open
Abstract
Two genes on chromosome 21, namely dual specificity tyrosine phosphorylation-regulated kinase 1A (Dyrk1A) and regulator of calcineurin 1 (RCAN1), have been implicated in some of the phenotypic characteristics of Down syndrome, including the early onset of Alzheimer disease. Although a link between Dyrk1A and RCAN1 and the nuclear factor of activated T cells (NFAT) pathway has been reported, it remains unclear whether Dyrk1A directly interacts with RCAN1. In the present study, Dyrk1A is shown to directly interact with and phosphorylate RCAN1 at Ser(112) and Thr(192) residues. Dyrk1A-mediated phosphorylation of RCAN1 at Ser(112) primes the protein for the GSK3β-mediated phosphorylation of Ser(108). Phosphorylation of RCAN1 at Thr(192) by Dyrk1A enhances the ability of RCAN1 to inhibit the phosphatase activity of calcineurin (Caln), leading to reduced NFAT transcriptional activity and enhanced Tau phosphorylation. These effects are mediated by the enhanced binding of RCAN1 to Caln and its extended half-life caused by Dyrk1A-mediated phosphorylation. Furthermore, an increased expression of phospho-Thr(192)-RCAN1 was observed in the brains of transgenic mice overexpressing the Dyrk1A protein. These results suggest a direct link between Dyrk1A and RCAN1 in the Caln-NFAT signaling and Tau hyperphosphorylation pathways, supporting the notion that the synergistic interaction between the chromosome 21 genes RCAN1 and Dyrk1A is associated with a variety of pathological features associated with DS.
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Affiliation(s)
- Min-Su Jung
- From the Graduate Program in Neuroscience, Institute for Brain Science and Technology, FIRST Research Group, Inje University, 633-146 Gaegeum-2-Dong, Busanjin-Gu, Busan 614-735, South Korea
| | - Jung-Hwa Park
- From the Graduate Program in Neuroscience, Institute for Brain Science and Technology, FIRST Research Group, Inje University, 633-146 Gaegeum-2-Dong, Busanjin-Gu, Busan 614-735, South Korea
| | - Young Shin Ryu
- From the Graduate Program in Neuroscience, Institute for Brain Science and Technology, FIRST Research Group, Inje University, 633-146 Gaegeum-2-Dong, Busanjin-Gu, Busan 614-735, South Korea
| | - Sun-Hee Choi
- From the Graduate Program in Neuroscience, Institute for Brain Science and Technology, FIRST Research Group, Inje University, 633-146 Gaegeum-2-Dong, Busanjin-Gu, Busan 614-735, South Korea
| | - Song-Hee Yoon
- From the Graduate Program in Neuroscience, Institute for Brain Science and Technology, FIRST Research Group, Inje University, 633-146 Gaegeum-2-Dong, Busanjin-Gu, Busan 614-735, South Korea
| | - Mi-Yang Kwen
- From the Graduate Program in Neuroscience, Institute for Brain Science and Technology, FIRST Research Group, Inje University, 633-146 Gaegeum-2-Dong, Busanjin-Gu, Busan 614-735, South Korea
| | - Ji Youn Oh
- From the Graduate Program in Neuroscience, Institute for Brain Science and Technology, FIRST Research Group, Inje University, 633-146 Gaegeum-2-Dong, Busanjin-Gu, Busan 614-735, South Korea
| | - Woo-Joo Song
- From the Graduate Program in Neuroscience, Institute for Brain Science and Technology, FIRST Research Group, Inje University, 633-146 Gaegeum-2-Dong, Busanjin-Gu, Busan 614-735, South Korea
| | - Sul-Hee Chung
- From the Graduate Program in Neuroscience, Institute for Brain Science and Technology, FIRST Research Group, Inje University, 633-146 Gaegeum-2-Dong, Busanjin-Gu, Busan 614-735, South Korea
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Ermak G, Pritchard MA, Dronjak S, Niu B, Davies KJA. Do RCAN1 proteins link chronic stress with neurodegeneration? FASEB J 2011; 25:3306-11. [PMID: 21680892 DOI: 10.1096/fj.11-185728] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
It has long been suspected that chronic stress can exacerbate, or even cause, disease. We now propose that the RCAN1 gene, which can generate several RCAN1 protein isoforms, may be at least partially responsible for this phenomenon. We review data showing that RCAN1 proteins can be induced by multiple stresses, and present new data also implicating psychosocial/emotional stress in RCAN1 induction. We further show that transgenic mice overexpressing the RCAN1-1L protein exhibit accumulation of hyperphosphorylated tau protein (AT8 antibody), an early precursor to the formation of neurofibrillary tangles and neurodegeneration of the kind seen in Alzheimer disease. We propose that, although transient induction of the RCAN1 gene might protect cells against acute stress, persistent stress may cause chronic RCAN1 overexpression, resulting in serious side effects. Chronically elevated levels of RCAN1 proteins may promote or exacerbate various diseases, including tauopathies such as Alzheimer disease. We propose that the mechanism by which stress can lead to these diseases involves the inhibition of calcineurin and the induction of GSK-3β by RCAN1 proteins. Both inhibition of calcineurin and induction of GSK-3β contribute to accumulation of phosphorylated tau, formation of neurofibrillary tangles, and eventual neurodegeneration.
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Affiliation(s)
- Gennady Ermak
- Ethel Percy Andrus Gerontology Center, Davis School of Gerontology, University of Southern California, 3715 McClintock Ave., Los Angeles, CA 90089-0191, USA
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96
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Lin LF, Luo HM. Screening of treatment targets for Alzheimer's disease from the molecular mechanisms of impairment by β-amyloid aggregation and tau hyperphosphorylation. Neurosci Bull 2011; 27:53-60. [PMID: 21270904 DOI: 10.1007/s12264-011-1040-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
β-Amyloid (Aβ) over-expression and tau hyperphosphorylation are considered to be the central events in the pathogenesis of Alzheimer's disease (AD). Studies on them may help elucidate the precise molecular pathogenesis of AD. Until now, although tau protein and Aβ remain the foci of AD research, the etiopathogenesis of AD and effective drugs for AD treatment are still largely unsolved. The present review was mainly focused on the molecular mechanism of Aβ aggregation-related impairment and the pathways leading to tau hyperphosphorylation, based on which some promising therapeutic targets for AD were also proposed.
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Affiliation(s)
- Lian-Feng Lin
- Department of Pharmacology, School of Medicine, Jinan University, Guangzhou 510632, China
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97
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Kim SI, Lee WK, Kang SS, Lee SY, Jeong MJ, Lee HJ, Kim SS, Johnson GVW, Chun W. Suppression of autophagy and activation of glycogen synthase kinase 3beta facilitate the aggregate formation of tau. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2011; 15:107-14. [PMID: 21660151 DOI: 10.4196/kjpp.2011.15.2.107] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 04/17/2011] [Accepted: 04/20/2011] [Indexed: 11/15/2022]
Abstract
Neurofibrillary tangle (NFT) is a characteristic hallmark of Alzheimer's disease. GSK3β has been reported to play a major role in the NFT formation of tau. Dysfunction of autophagy might facilitate the aggregate formation of tau. The present study examined the role of GSK3β-mediated phosphorylation of tau species on their autophagic degradation. We transfected wild type tau (T4), caspase-3-cleaved tau at Asp421 (T4C3), or pseudophosphorylated tau at Ser396/Ser404 (T4-2EC) in the presence of active or enzyme-inactive GSK3β. Trehalose and 3-methyladenine (3-MA) were used to enhance or inhibit autophagic activity, respectively. All tau species showed increased accumulation with 3-MA treatment whereas reduced with trehalose, indicating that tau undergoes autophagic degradation. However, T4C3 and T4-2EC showed abundant formation of oligomers than T4. Active GSK3β in the presence of 3-MA resulted in significantly increased formation of insoluble tau aggregates. These results indicate that GSK3β-mediated phosphorylation and compromised autophagic activity significantly contribute to tau aggregation.
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Affiliation(s)
- Song-In Kim
- Department of Pharmacology, College of Medicine, Kangwon National University, Chunchon 200-701, Korea
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98
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De Vos A, Anandhakumar J, Van den Brande J, Verduyckt M, Franssens V, Winderickx J, Swinnen E. Yeast as a model system to study tau biology. Int J Alzheimers Dis 2011; 2011:428970. [PMID: 21559193 PMCID: PMC3090044 DOI: 10.4061/2011/428970] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 01/21/2011] [Indexed: 11/20/2022] Open
Abstract
Hyperphosphorylated and aggregated human protein tau constitutes a hallmark of a multitude of neurodegenerative diseases called tauopathies, exemplified by Alzheimer's disease. In spite of an enormous amount of research performed on tau biology, several crucial questions concerning the mechanisms of tau toxicity remain unanswered. In this paper we will highlight some of the processes involved in tau biology and pathology, focusing on tau phosphorylation and the interplay with oxidative stress. In addition, we will introduce the development of a human tau-expressing yeast model, and discuss some crucial results obtained in this model, highlighting its potential in the elucidation of cellular processes leading to tau toxicity.
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Affiliation(s)
- Ann De Vos
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Jayamani Anandhakumar
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Jeff Van den Brande
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Mathias Verduyckt
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Vanessa Franssens
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Joris Winderickx
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
| | - Erwin Swinnen
- Laboratory of Functional Biology, Catholic University of Leuven, Kasteelpark Arenberg 31, 3001 Heverlee, Belgium
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Stoppelkamp S, Bell HS, Palacios-Filardo J, Shewan DA, Riedel G, Platt B. In vitro modelling of Alzheimer's disease: degeneration and cell death induced by viral delivery of amyloid and tau. Exp Neurol 2011; 229:226-37. [PMID: 21295028 DOI: 10.1016/j.expneurol.2011.01.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 01/20/2011] [Accepted: 01/24/2011] [Indexed: 11/15/2022]
Abstract
With increasing life expectancy, Alzheimer's disease (AD) and other dementias pose an increasing and as yet unresolved health problem. A variety of cellular models of AD has helped to decipher some key aspects of amyloid and tau related degeneration. The initial approach of extracellular applications of synthetic peptides has now been replaced by the introduction of amyloid precursor protein (APP) and tau genes. In the present study adenoviral transductions were exploited for gene delivery into primary rat hippocampal and dorsal root ganglion (DRG) cultures to enable comparative and mechanistic studies at the cellular level and subsequent drug testing. Time lapse experiments revealed a different pattern of cell death: apoptotic-like for APP whereas tau positive cells joined and formed clusters. Mutated human APP or tau expression caused accelerated neuronal damage and cell death (cf. EGFP: -50% for APP at 5 days; -40% for tau at 3 days). This reduction in viability was preceded by decreased excitability, monitored via responses to depolarising KCl-challenges in Ca(2+) imaging experiments. Additionally, both transgenes reduced neurite outgrowth in DRG neurones. Treatment studies confirmed that APP induced-damage can be ameliorated by β- and γ-secretase inhibitors (providing protection to 60-100% of control levels), clioquinol (80%) and lithium (100%); while anti-aggregation treatments were beneficial for tau-induced damage (60-90% recovery towards controls). Interestingly, caffeine was the most promising drug candidate for therapeutic intervention with high efficacy in both APP (77%) and tau-induced models (72% recovery). Overall, these cellular models offer advantages for mechanistic studies and target identification in AD and related disorders.
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Affiliation(s)
- Sandra Stoppelkamp
- School of Medical Sciences, College of Life Sciences and Medicine, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD Scotland, UK
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Yuraszeck TM, Neveu P, Rodriguez-Fernandez M, Robinson A, Kosik KS, Doyle FJ. Vulnerabilities in the tau network and the role of ultrasensitive points in tau pathophysiology. PLoS Comput Biol 2010; 6:e1000997. [PMID: 21085645 PMCID: PMC2978700 DOI: 10.1371/journal.pcbi.1000997] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Accepted: 10/12/2010] [Indexed: 11/18/2022] Open
Abstract
The multifactorial nature of disease motivates the use of systems-level analyses to understand their pathology. We used a systems biology approach to study tau aggregation, one of the hallmark features of Alzheimer's disease. A mathematical model was constructed to capture the current state of knowledge concerning tau's behavior and interactions in cells. The model was implemented in silico in the form of ordinary differential equations. The identifiability of the model was assessed and parameters were estimated to generate two cellular states: a population of solutions that corresponds to normal tau homeostasis and a population of solutions that displays aggregation-prone behavior. The model of normal tau homeostasis was robust to perturbations, and disturbances in multiple processes were required to achieve an aggregation-prone state. The aggregation-prone state was ultrasensitive to perturbations in diverse subsets of networks. Tau aggregation requires that multiple cellular parameters are set coordinately to a set of values that drive pathological assembly of tau. This model provides a foundation on which to build and increase our understanding of the series of events that lead to tau aggregation and may ultimately be used to identify critical intervention points that can direct the cell away from tau aggregation to aid in the treatment of tau-mediated (or related) aggregation diseases including Alzheimer's.
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Affiliation(s)
- Theresa M. Yuraszeck
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California, United States of America
| | - Pierre Neveu
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, California, United States of America
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, California, United States of America
| | | | - Anne Robinson
- Department of Chemical Engineering, University of Delaware, Newark, Delaware, United States of America
| | - Kenneth S. Kosik
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, California, United States of America
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, United States of America
| | - Francis J. Doyle
- Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California, United States of America
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara, California, United States of America
- * E-mail:
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