1
|
Rajah Kumaran K, Yunusa S, Perimal E, Wahab H, Müller CP, Hassan Z. Insights into the Pathophysiology of Alzheimer's Disease and Potential Therapeutic Targets: A Current Perspective. J Alzheimers Dis 2023; 91:507-530. [PMID: 36502321 DOI: 10.3233/jad-220666] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The aging population increases steadily because of a healthy lifestyle and medical advancements in healthcare. However, Alzheimer's disease (AD) is becoming more common and problematic among older adults. AD-related cases show an increasing trend annually, and the younger age population may also be at risk of developing this disorder. AD constitutes a primary form of dementia, an irreversible and progressive brain disorder that steadily damages cognitive functions and the ability to perform daily tasks. Later in life, AD leads to death as a result of the degeneration of specific brain areas. Currently, the cause of AD is poorly understood, and there is no safe and effective therapeutic agent to cure or slow down its progression. The condition is entirely preventable, and no study has yet demonstrated encouraging findings in terms of treatment. Identifying this disease's pathophysiology can help researchers develop safe and efficient therapeutic strategies to treat this ailment. This review outlines and discusses the pathophysiology that resulted in the development of AD including amyloid-β plaques, tau neurofibrillary tangles, neuroinflammation, oxidative stress, cholinergic dysfunction, glutamate excitotoxicity, and changes in neurotrophins level may sound better based on the literature search from Scopus, PubMed, ScienceDirect, and Google Scholar. Potential therapeutic strategies are discussed to provide more insights into AD mechanisms by developing some possible pharmacological agents for its treatment.
Collapse
Affiliation(s)
- Kesevan Rajah Kumaran
- Malaysian Institute of Pharmaceuticals and Nutraceuticals, National Institutes of Biotechnology Malaysia, Halaman Bukit Gambir, Gelugor, Pulau Pinang, Malaysia
| | - Suleiman Yunusa
- Centre for Drug Research, Universiti Sains Malaysia, Penang, Malaysia.,Department of Pharmacology, Bauchi State University Gadau, Bauchi State, Nigeria
| | - Enoch Perimal
- Curtin Medical School, Curtin University, Bentley, Western Australia, Australia.,Department of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Malaysia
| | - Habibah Wahab
- School of Pharmaceutical Sciences, Universiti Sains Malaysia, Penang, Malaysia
| | - Christian P Müller
- Centre for Drug Research, Universiti Sains Malaysia, Penang, Malaysia.,Section of Addiction Medicine, Department of Psychiatry and Psychotherapy, University Clinic, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| | - Zurina Hassan
- Centre for Drug Research, Universiti Sains Malaysia, Penang, Malaysia.,Section of Addiction Medicine, Department of Psychiatry and Psychotherapy, University Clinic, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
| |
Collapse
|
2
|
Mendsaikhan A, Tooyama I, Serrano GE, Beach TG, Walker DG. Loss of Lysosomal Proteins Progranulin and Prosaposin Associated with Increased Neurofibrillary Tangle Development in Alzheimer Disease. J Neuropathol Exp Neurol 2021; 80:741-753. [PMID: 34374777 PMCID: PMC8433593 DOI: 10.1093/jnen/nlab056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Alzheimer disease (AD) is a progressive neurodegenerative disease causing cognitive decline in the aging population. To develop disease-modifying treatments, understanding the mechanisms behind the pathology is important, which should include observations using human brain samples. We reported previously on the association of lysosomal proteins progranulin (PGRN) and prosaposin (PSAP) with amyloid plaques in non-demented aged control and AD brains. In this study, we investigated the possible involvement of PGRN and PSAP in tangle formation using human brain tissue sections of non-demented aged control subjects and AD cases and compared with cases of frontotemporal dementia with granulin (GRN) mutations. The study revealed that decreased amounts of PGRN and PSAP proteins were detected even in immature neurofibrillary tangles, while colocalization was still evident in adjacent neurons in all cases. Results suggest that neuronal loss of PGRN preceded loss of PSAP as tangles developed and matured. The GRN mutation cases exhibited almost complete absence of PGRN in most neurons, while PSAP signal was preserved. Although based on correlative data, we suggest that reduced levels of PGRN and PSAP and their interaction in neurons might predispose to accumulation of p-Tau protein.
Collapse
Affiliation(s)
- Anarmaa Mendsaikhan
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga, Japan (AM, IT, DGW)
| | - Ikuo Tooyama
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga, Japan (AM, IT, DGW)
| | - Geidy E Serrano
- Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, Arizona (GES, TGB)
| | - Thomas G Beach
- Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, Arizona (GES, TGB)
| | - Douglas G Walker
- Molecular Neuroscience Research Center, Shiga University of Medical Science, Otsu, Shiga, Japan (AM, IT, DGW)
- School of Life Sciences and Neurodegenerative Disease Research Center, Arizona State University, Tempe, Arizona (DGW)
| |
Collapse
|
3
|
Ahmed T, Van der Jeugd A, Caillierez R, Buée L, Blum D, D'Hooge R, Balschun D. Chronic Sodium Selenate Treatment Restores Deficits in Cognition and Synaptic Plasticity in a Murine Model of Tauopathy. Front Mol Neurosci 2020; 13:570223. [PMID: 33132838 PMCID: PMC7578417 DOI: 10.3389/fnmol.2020.570223] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 08/26/2020] [Indexed: 12/18/2022] Open
Abstract
A major goal in diseases is identifying a potential therapeutic agent that is cost-effective and can remedy some, if not all, disease symptoms. In Alzheimer’s disease (AD), aggregation of hyperphosphorylated tau protein is one of the neuropathological hallmarks, and Tau pathology correlates better with cognitive impairments in AD patients than amyloid-β load, supporting a key role of tau-related mechanisms. Selenium is a non-metallic trace element that is incorporated in the brain into selenoproteins. Chronic treatment with sodium selenate, a non-toxic selenium compound, was recently reported to rescue behavioral phenotypes in tau mouse models. Here, we focused on the effects of chronic selenate application on synaptic transmission and synaptic plasticity in THY-Tau22 mice, a transgenic animal model of tauopathies. Three months with a supplement of sodium selenate in the drinking water (12 μg/ml) restored not only impaired neurocognitive functions but also rescued long-term depression (LTD), a major form of synaptic plasticity. Furthermore, selenate reduced the inactive demethylated catalytic subunit of protein phosphatase 2A (PP2A) in THY-Tau22 without affecting total PP2A.Our study provides evidence that chronic dietary selenate rescues functional synaptic deficits of tauopathy and identifies activation of PP2A as the putative mechanism.
Collapse
Affiliation(s)
- Tariq Ahmed
- Brain and Cognition, Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium.,Leuven Brain Institute, Leuven, Belgium
| | - Ann Van der Jeugd
- Leuven Brain Institute, Leuven, Belgium.,Laboratory of Biological Psychology, Brain and Cognition, Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium
| | - Raphaëlle Caillierez
- Univ. Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience and Cognition, Lille, France.,Alzheimer and Tauopathies, LabEx DISTALZ, Lille, France
| | - Luc Buée
- Univ. Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience and Cognition, Lille, France.,Alzheimer and Tauopathies, LabEx DISTALZ, Lille, France
| | - David Blum
- Univ. Lille, Inserm, CHU Lille, U1172-LilNCog-Lille Neuroscience and Cognition, Lille, France.,Alzheimer and Tauopathies, LabEx DISTALZ, Lille, France
| | - Rudi D'Hooge
- Leuven Brain Institute, Leuven, Belgium.,Laboratory of Biological Psychology, Brain and Cognition, Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium
| | - Detlef Balschun
- Brain and Cognition, Faculty of Psychology and Educational Sciences, KU Leuven, Leuven, Belgium.,Leuven Brain Institute, Leuven, Belgium
| |
Collapse
|
4
|
Clark AR, Ohlmeyer M. Protein phosphatase 2A as a therapeutic target in inflammation and neurodegeneration. Pharmacol Ther 2019; 201:181-201. [PMID: 31158394 PMCID: PMC6700395 DOI: 10.1016/j.pharmthera.2019.05.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 05/29/2019] [Indexed: 12/11/2022]
Abstract
Protein phosphatase 2A (PP2A) is a highly complex heterotrimeric enzyme that catalyzes the selective removal of phosphate groups from protein serine and threonine residues. Emerging evidence suggests that it functions as a tumor suppressor by constraining phosphorylation-dependent signalling pathways that regulate cellular transformation and metastasis. Therefore, PP2A-activating drugs (PADs) are being actively sought and investigated as potential novel anti-cancer treatments. Here we explore the concept that PP2A also constrains inflammatory responses through its inhibitory effects on various signalling pathways, suggesting that PADs may be effective in the treatment of inflammation-mediated pathologies.
Collapse
Affiliation(s)
- Andrew R Clark
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
| | | |
Collapse
|
5
|
Physiologic functions of PP2A: Lessons from genetically modified mice. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:31-50. [DOI: 10.1016/j.bbamcr.2018.07.010] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 07/11/2018] [Accepted: 07/14/2018] [Indexed: 01/03/2023]
|
6
|
Hoffman A, Taleski G, Sontag E. The protein serine/threonine phosphatases PP2A, PP1 and calcineurin: A triple threat in the regulation of the neuronal cytoskeleton. Mol Cell Neurosci 2017; 84:119-131. [PMID: 28126489 DOI: 10.1016/j.mcn.2017.01.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 01/16/2017] [Accepted: 01/21/2017] [Indexed: 01/08/2023] Open
Abstract
The microtubule, F-actin and neurofilament networks play a critical role in neuronal cell morphogenesis, polarity and synaptic plasticity. Significantly, the assembly/disassembly and stability of these cytoskeletal networks is crucially modulated by protein phosphorylation and dephosphorylation events. Herein, we aim to more closely examine the role played by three major neuronal Ser/Thr protein phosphatases, PP2A, PP1 and calcineurin, in the homeostasis of the neuronal cytoskeleton. There is strong evidence that these enzymes interact with and dephosphorylate a variety of cytoskeletal proteins, resulting in major regulation of neuronal cytoskeletal dynamics. Conversely, we also discuss how multi-protein cytoskeletal scaffolds can also influence the regulation of these phosphatases, with important implications for neuronal signalling and homeostasis. Not surprisingly, deregulation of these cytoskeletal scaffolds and phosphatase dysfunction are associated with many neurological diseases.
Collapse
Affiliation(s)
- Alexander Hoffman
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, and Hunter Medical Research Institute, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Goce Taleski
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, and Hunter Medical Research Institute, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Estelle Sontag
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, and Hunter Medical Research Institute, University of Newcastle, Callaghan, NSW 2308, Australia.
| |
Collapse
|
7
|
Tiernan CT, Combs B, Cox K, Morfini G, Brady ST, Counts SE, Kanaan NM. Pseudophosphorylation of tau at S422 enhances SDS-stable dimer formation and impairs both anterograde and retrograde fast axonal transport. Exp Neurol 2016; 283:318-29. [PMID: 27373205 PMCID: PMC4992631 DOI: 10.1016/j.expneurol.2016.06.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 06/22/2016] [Accepted: 06/28/2016] [Indexed: 12/17/2022]
Abstract
In Alzheimer's disease (AD), tau undergoes numerous modifications, including increased phosphorylation at serine-422 (pS422). In the human brain, pS422 tau protein is found in prodromal AD, correlates well with cognitive decline and neuropil thread pathology, and appears associated with increased oligomer formation and exposure of the N-terminal phosphatase-activating domain (PAD). However, whether S422 phosphorylation contributes to toxic mechanisms associated with disease-related forms of tau remains unknown. Here, we report that S422-pseudophosphorylated tau (S422E) lengthens the nucleation phase of aggregation without altering the extent of aggregation or the types of aggregates formed. When compared to unmodified tau aggregates, the S422E modification significantly increased the amount of SDS-stable tau dimers, despite similar levels of immunoreactivity with an oligomer-selective antibody (TOC1) and another antibody that reports PAD exposure (TNT1). Vesicle motility assays in isolated squid axoplasm further revealed that S422E tau monomers inhibited anterograde, kinesin-1 dependent fast axonal transport (FAT). Unexpectedly, and unlike unmodified tau aggregates, which selectively inhibit anterograde FAT, aggregates composed of S422E tau were found to inhibit both anterograde and retrograde FAT. Highlighting the relevance of these findings to human disease, pS422 tau was found to colocalize with tau oligomers and with a fraction of tau showing increased PAD exposure in the human AD brain. This study identifies novel effects of pS422 on tau biochemical properties, including prolonged nucleation and enhanced dimer formation, which correlate with a distinct inhibitory effect on FAT. Taken together, these findings identify a novel mechanistic basis by which pS422 confers upon tau a toxic effect that may directly contribute to axonal dysfunction in AD and other tauopathies.
Collapse
Affiliation(s)
- Chelsea T Tiernan
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Benjamin Combs
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Kristine Cox
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Gerardo Morfini
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, IL 60612, USA
| | - Scott T Brady
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, IL 60612, USA
| | - Scott E Counts
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI 49503, USA; Department of Family Medicine, Michigan State University, Grand Rapids, MI 49503, USA; Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA; Hauenstein Neuroscience Center, Mercy Health Saint Mary's Hospital, Grand Rapids, MI 49503, USA
| | - Nicholas M Kanaan
- Department of Translational Science and Molecular Medicine, Michigan State University, Grand Rapids, MI 49503, USA; Neuroscience Program, Michigan State University, East Lansing, MI 48824, USA; Hauenstein Neuroscience Center, Mercy Health Saint Mary's Hospital, Grand Rapids, MI 49503, USA.
| |
Collapse
|
8
|
Bodea L, Eckert A, Ittner LM, Piguet O, Götz J. Tau physiology and pathomechanisms in frontotemporal lobar degeneration. J Neurochem 2016; 138 Suppl 1:71-94. [PMID: 27306859 PMCID: PMC5094566 DOI: 10.1111/jnc.13600] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 01/31/2016] [Accepted: 02/24/2016] [Indexed: 12/27/2022]
Abstract
Frontotemporal lobar degeneration (FTLD) has been associated with toxic intracellular aggregates of hyperphosphorylated tau (FTLD-tau). Moreover, genetic studies identified mutations in the MAPT gene encoding tau in familial cases of the disease. In this review, we cover a range of aspects of tau function, both in the healthy and diseased brain, discussing several in vitro and in vivo models. Tau structure and function in the healthy brain is presented, accentuating its distinct compartmentalization in neurons and its role in microtubule stabilization and axonal transport. Furthermore, tau-driven pathology is discussed, introducing current concepts and the underlying experimental evidence. Different aspects of pathological tau phosphorylation, the protein's genomic and domain organization as well as its spreading in disease, together with MAPT-associated mutations and their respective models are presented. Dysfunction related to other post-transcriptional modifications and their effect on normal neuronal functions such as cell cycle, epigenetics and synapse dynamics are also discussed, providing a mechanistic explanation for the observations made in FTLD-tau cases, with the possibility for therapeutic intervention. In this review, we cover aspects of tau function, both in the healthy and diseased brain, referring to different in vitro and in vivo models. In healthy neurons, tau is compartmentalized, with higher concentrations found in the distal part of the axon. Cargo molecules are sensitive to this gradient. A disturbed tau distribution, as found in frontotemporal lobar degeneration (FTLD-tau), has severe consequences for cellular physiology: tau accumulates in the neuronal soma and dendrites, leading among others to microtubule depolymerization and impaired axonal transport. Tau forms insoluble aggregates that sequester additional molecules stalling cellular physiology. Neuronal communication is gradually lost as toxic tau accumulates in dendritic spines with subsequent degeneration of synapses and synaptic loss. Thus, by providing a mechanistic explanation for the observations made in FTLD-tau cases, arises a possibility for therapeutic interventions. This article is part of the Frontotemporal Dementia special issue.
Collapse
Affiliation(s)
- Liviu‐Gabriel Bodea
- Clem Jones Centre for Ageing Dementia ResearchQueensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - Anne Eckert
- Neurobiology LaboratoryPsychiatric University Clinics BaselUniversity of BaselBaselSwitzerland
| | - Lars Matthias Ittner
- Dementia Research UnitSchool of Medical SciencesFaculty of MedicineUniversity of New South WalesSydneyNSWAustralia
| | | | - Jürgen Götz
- Clem Jones Centre for Ageing Dementia ResearchQueensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| |
Collapse
|
9
|
Yang CC, Kuai XX, Gao WB, Yu JC, Wang Q, Li L, Zhang L. Morroniside-Induced PP2A Activation Antagonizes Tau Hyperphosphorylation in a Cellular Model of Neurodegeneration. J Alzheimers Dis 2016; 51:33-44. [PMID: 26836014 DOI: 10.3233/jad-150728] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Cui-cui Yang
- Department of Pharmacology, Xuanwu Hospital of Capital Medical University; Beijing Institute for Brain disorder; Beijing Engineering Research Center for Nerve System Drugs; Key Laboratory for Neurodegenerative Diseases of Ministry of Education, Beijing, China
| | - Xue-xian Kuai
- Department of Pharmacology, Xuanwu Hospital of Capital Medical University; Beijing Institute for Brain disorder; Beijing Engineering Research Center for Nerve System Drugs; Key Laboratory for Neurodegenerative Diseases of Ministry of Education, Beijing, China
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Wen-bin Gao
- Department of Pharmacology, Xuanwu Hospital of Capital Medical University; Beijing Institute for Brain disorder; Beijing Engineering Research Center for Nerve System Drugs; Key Laboratory for Neurodegenerative Diseases of Ministry of Education, Beijing, China
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jian-chun Yu
- First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Qi Wang
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Lin Li
- Department of Pharmacology, Xuanwu Hospital of Capital Medical University; Beijing Institute for Brain disorder; Beijing Engineering Research Center for Nerve System Drugs; Key Laboratory for Neurodegenerative Diseases of Ministry of Education, Beijing, China
| | - Lan Zhang
- Department of Pharmacology, Xuanwu Hospital of Capital Medical University; Beijing Institute for Brain disorder; Beijing Engineering Research Center for Nerve System Drugs; Key Laboratory for Neurodegenerative Diseases of Ministry of Education, Beijing, China
| |
Collapse
|
10
|
El Khoury NB, Gratuze M, Papon MA, Bretteville A, Planel E. Insulin dysfunction and Tau pathology. Front Cell Neurosci 2014; 8:22. [PMID: 24574966 PMCID: PMC3920186 DOI: 10.3389/fncel.2014.00022] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 01/16/2014] [Indexed: 01/26/2023] Open
Abstract
The neuropathological hallmarks of Alzheimer's disease (AD) include senile plaques of β-amyloid (Aβ) peptides (a cleavage product of the Amyloid Precursor Protein, or APP) and neurofibrillary tangles (NFT) of hyperphosphorylated Tau protein assembled in paired helical filaments (PHF). NFT pathology is important since it correlates with the degree of cognitive impairment in AD. Only a small proportion of AD is due to genetic variants, whereas the large majority of cases (~99%) is late onset and sporadic in origin. The cause of sporadic AD is likely to be multifactorial, with external factors interacting with biological or genetic susceptibilities to accelerate the manifestation of the disease. Insulin dysfunction, manifested by diabetes mellitus (DM) might be such factor, as there is extensive data from epidemiological studies suggesting that DM is associated with an increased relative risk for AD. Type 1 diabetes (T1DM) and type 2 diabetes (T2DM) are known to affect multiple cognitive functions in patients. In this context, understanding the effects of diabetes on Tau pathogenesis is important since Tau pathology show a strong relationship to dementia in AD, and to memory loss in normal aging and mild cognitive impairment. Here, we reviewed preclinical studies that link insulin dysfunction to Tau protein pathogenesis, one of the major pathological hallmarks of AD. We found more than 30 studies reporting Tau phosphorylation in a mouse or rat model of insulin dysfunction. We also payed attention to potential sources of artifacts, such as hypothermia and anesthesia, that were demonstrated to results in Tau hyperphosphorylation and could major confounding experimental factors. We found that very few studies reported the temperature of the animals, and only a handful did not use anesthesia. Overall, most published studies showed that insulin dysfunction can promote Tau hyperphosphorylation and pathology, both directly and indirectly, through hypothermia.
Collapse
Affiliation(s)
- Noura B El Khoury
- Département de Psychiatrie et Neurosciences, Faculté de Médecine, Université Laval Québec, QC, Canada ; Axe Neurosciences, Centre Hospitalier de l'Université Laval Québec, QC, Canada
| | - Maud Gratuze
- Département de Psychiatrie et Neurosciences, Faculté de Médecine, Université Laval Québec, QC, Canada ; Axe Neurosciences, Centre Hospitalier de l'Université Laval Québec, QC, Canada
| | - Marie-Amélie Papon
- Axe Neurosciences, Centre Hospitalier de l'Université Laval Québec, QC, Canada
| | - Alexis Bretteville
- Axe Neurosciences, Centre Hospitalier de l'Université Laval Québec, QC, Canada
| | - Emmanuel Planel
- Département de Psychiatrie et Neurosciences, Faculté de Médecine, Université Laval Québec, QC, Canada ; Axe Neurosciences, Centre Hospitalier de l'Université Laval Québec, QC, Canada
| |
Collapse
|
11
|
Hyperphosphorylated Tau is Implicated in Acquired Epilepsy and Neuropsychiatric Comorbidities. Mol Neurobiol 2013; 49:1532-9. [DOI: 10.1007/s12035-013-8601-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 11/26/2013] [Indexed: 02/06/2023]
|
12
|
Eckert A, Nisbet R, Grimm A, Götz J. March separate, strike together--role of phosphorylated TAU in mitochondrial dysfunction in Alzheimer's disease. Biochim Biophys Acta Mol Basis Dis 2013; 1842:1258-66. [PMID: 24051203 DOI: 10.1016/j.bbadis.2013.08.013] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/08/2013] [Accepted: 08/12/2013] [Indexed: 12/17/2022]
Abstract
The energy demand and calcium buffering requirements of the brain are met by the high number of mitochondria in neurons and in these, especially at the synapses. Mitochondria are the major producer of reactive oxygen species (ROS); at the same time, they are damaged by ROS that are induced by abnormal protein aggregates that characterize human neurodegenerative diseases such as Alzheimer's disease (AD). Because synaptic mitochondria are long-lived, any damage exerted by these aggregates impacts severely on neuronal function. Here we review how increased TAU, a defining feature of AD and related tauopathies, impairs mitochondrial function by following the principle: 'March separate, strike together!' In the presence of amyloid-β, TAU's toxicity is augmented suggesting synergistic pathomechanisms. In order to restore mitochondrial functions in neurodegeneration as a means of therapeutic intervention it will be important to integrate the various aspects of dysfunction and get a handle on targeting distinct cell types and subcellular compartments.
Collapse
Affiliation(s)
- Anne Eckert
- Neurobiology Laboratory, Psychiatric University Clinics Basel, University of Basel, Switzerland
| | - Rebecca Nisbet
- Centre for Ageing Dementia Research (CADR), Queensland Brain Institute (QBI), The University of Queensland, Australia
| | - Amandine Grimm
- Neurobiology Laboratory, Psychiatric University Clinics Basel, University of Basel, Switzerland
| | - Jürgen Götz
- Centre for Ageing Dementia Research (CADR), Queensland Brain Institute (QBI), The University of Queensland, Australia.
| |
Collapse
|
13
|
MacKay KB, Tu Y, Young SG, Clarke SG. Circumventing embryonic lethality with Lcmt1 deficiency: generation of hypomorphic Lcmt1 mice with reduced protein phosphatase 2A methyltransferase expression and defects in insulin signaling. PLoS One 2013; 8:e65967. [PMID: 23840384 PMCID: PMC3688711 DOI: 10.1371/journal.pone.0065967] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 05/03/2013] [Indexed: 11/18/2022] Open
Abstract
Protein phosphatase 2A (PP2A), the major serine/threonine phosphatase in eukaryotic cells, is a heterotrimeric protein composed of structural, catalytic, and targeting subunits. PP2A assembly is governed by a variety of mechanisms, one of which is carboxyl-terminal methylation of the catalytic subunit by the leucine carboxyl methyltransferase LCMT1. PP2A is nearly stoichiometrically methylated in the cytosol, and although some PP2A targeting subunits bind independently of methylation, this modification is required for the binding of others. To examine the role of this methylation reaction in mammalian tissues, we generated a mouse harboring a gene-trap cassette within intron 1 of Lcmt1. Due to splicing around the insertion, Lcmt1 transcript and LCMT1 protein levels were reduced but not eliminated. LCMT1 activity and methylation of PP2A were reduced in a coordinate fashion, suggesting that LCMT1 is the only PP2A methyltransferase. These mice exhibited an insulin-resistance phenotype, indicating a role for this methyltransferase in signaling in insulin-sensitive tissues. Tissues from these animals will be vital for the in vivo identification of methylation-sensitive substrates of PP2A and how they respond to differing physiological conditions.
Collapse
Affiliation(s)
- Kennen B. MacKay
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America
| | - Yiping Tu
- Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
| | - Stephen G. Young
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Human Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Steven G. Clarke
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, California, United States of America
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America
- * E-mail:
| |
Collapse
|
14
|
Götz J, Xia D, Leinenga G, Chew YL, Nicholas HR. What Renders TAU Toxic. Front Neurol 2013; 4:72. [PMID: 23772223 PMCID: PMC3677143 DOI: 10.3389/fneur.2013.00072] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 05/28/2013] [Indexed: 12/21/2022] Open
Abstract
TAU is a microtubule-associated protein that under pathological conditions such as Alzheimer's disease (AD) forms insoluble, filamentous aggregates. When 20 years after TAU's discovery the first TAU transgenic mouse models were established, one declared goal that was achieved was the modeling of authentic TAU aggregate formation in the form of neurofibrillary tangles. However, as we review here, it has become increasingly clear that TAU causes damage much before these filamentous aggregates develop. In fact, because TAU is a scaffolding protein, increased levels and an altered subcellular localization (due to an increased insolubility and impaired clearance) result in the interaction of TAU with cellular proteins with which it would otherwise either not interact or do so to a lesser degree, thereby impairing their physiological functions. We specifically discuss the non-axonal localization of TAU, the role phosphorylation has in TAU toxicity and how TAU impairs mitochondrial functions. A major emphasis is on what we have learned from the four available TAU knock-out models in mice, and the knock-out of the TAU/MAP2 homolog PTL-1 in worms. It has been proposed that in human pathological conditions such as AD, a rare toxic TAU species exists which needs to be specifically removed to abrogate TAU's toxicity and restore neuronal functions. However, what is toxic in one context may not be in another, and simply reducing, but not fully abolishing TAU levels may be sufficient to abrogate TAU toxicity.
Collapse
Affiliation(s)
- Jürgen Götz
- Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
- Sydney Medical School, Brain and Mind Research Institute, University of Sydney, Sydney, NSW, Australia
| | - Di Xia
- Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Gerhard Leinenga
- Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Yee Lian Chew
- School of Molecular Bioscience, University of Sydney, Sydney, NSW, Australia
| | - Hannah R. Nicholas
- School of Molecular Bioscience, University of Sydney, Sydney, NSW, Australia
| |
Collapse
|
15
|
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: 160] [Impact Index Per Article: 14.5] [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.
Collapse
Affiliation(s)
- Ludovic Martin
- Groupe de Neurobiologie Cellulaire, Homéostasie cellulaire et pathologies, Faculté de Médecine, Limoges, France.
| | | | | | | | | | | |
Collapse
|
16
|
Gerecke KM, Jiao Y, Pagala V, Smeyne RJ. Exercise does not protect against MPTP-induced neurotoxicity in BDNF haploinsufficient mice. PLoS One 2012; 7:e43250. [PMID: 22912838 PMCID: PMC3422268 DOI: 10.1371/journal.pone.0043250] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 07/18/2012] [Indexed: 02/06/2023] Open
Abstract
Exercise has been demonstrated to potently protect substantia nigra pars compacta (SN) dopaminergic neurons from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity. One mechanism proposed to account for this neuroprotection is the upregulation of neurotrophic factors. Several neurotrophic factors, including Brain Derived Neurotrophic Factor (BDNF), have been shown to upregulate in response to exercise. In order to determine if exercise-induced neuroprotection is dependent upon BDNF, we compared the neuroprotective effects of voluntary exercise in mice heterozygous for the BDNF gene (BDNF+/-) with strain-matched wild-type (WT) mice. Stereological estimates of SNpc DA neurons from WT mice allowed 90 days exercise via unrestricted running demonstrated complete protection against the MPTP-induced neurotoxicity. However, BDNF+/- mice allowed 90 days of unrestricted exercise were not protected from MPTP-induced SNpc DA neuron loss. Proteomic analysis comparing SN and striatum from 90 day exercised WT and BDNF+/- mice showed differential expression of proteins related to energy regulation, intracellular signaling and trafficking. These results suggest that a full genetic complement of BDNF is critical for the exercise-induced neuroprotection of SNpc DA neurons.
Collapse
Affiliation(s)
- Kim M Gerecke
- Department of Psychology and Neuroscience Program, Rhodes College, Memphis, Tennessee, United States of America.
| | | | | | | |
Collapse
|
17
|
Ke Y, Dramiga J, Schütz U, Kril JJ, Ittner LM, Schröder H, Götz J. Tau-mediated nuclear depletion and cytoplasmic accumulation of SFPQ in Alzheimer's and Pick's disease. PLoS One 2012; 7:e35678. [PMID: 22558197 PMCID: PMC3338448 DOI: 10.1371/journal.pone.0035678] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 03/20/2012] [Indexed: 11/19/2022] Open
Abstract
Tau dysfunction characterizes neurodegenerative diseases such as Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD). Here, we performed an unbiased SAGE (serial analysis of gene expression) of differentially expressed mRNAs in the amygdala of transgenic pR5 mice that express human tau carrying the P301L mutation previously identified in familial cases of FTLD. SAGE identified 29 deregulated transcripts including Sfpq that encodes a nuclear factor implicated in the splicing and regulation of gene expression. To assess the relevance for human disease we analyzed brains from AD, Pick's disease (PiD, a form of FTLD), and control cases. Strikingly, in AD and PiD, both dementias with a tau pathology, affected brain areas showed a virtually complete nuclear depletion of SFPQ in both neurons and astrocytes, along with cytoplasmic accumulation. Accordingly, neurons harboring either AD tangles or Pick bodies were also depleted of SFPQ. Immunoblot analysis of human entorhinal cortex samples revealed reduced SFPQ levels with advanced Braak stages suggesting that the SFPQ pathology may progress together with the tau pathology in AD. To determine a causal role for tau, we stably expressed both wild-type and P301L human tau in human SH-SY5Y neuroblastoma cells, an established cell culture model of tau pathology. The cells were differentiated by two independent methods, mitomycin C-mediated cell cycle arrest or neuronal differentiation with retinoic acid. Confocal microscopy revealed that SFPQ was confined to nuclei in non-transfected wild-type cells, whereas in wild-type and P301L tau over-expressing cells, irrespective of the differentiation method, it formed aggregates in the cytoplasm, suggesting that pathogenic tau drives SFPQ pathology in post-mitotic cells. Our findings add SFPQ to a growing list of transcription factors with an altered nucleo-cytoplasmic distribution under neurodegenerative conditions.
Collapse
Affiliation(s)
- Yazi Ke
- Alzheimer's and Parkinson's Disease Laboratory, Brain & Mind Research Institute, University of Sydney, Camperdown, New South Wales, Australia
| | - Joe Dramiga
- Department II of Anatomy and Neuroanatomy, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, CMMC, University of Cologne, Cologne, Germany
| | - Ulrich Schütz
- Department II of Anatomy and Neuroanatomy, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, CMMC, University of Cologne, Cologne, Germany
| | - Jillian J. Kril
- Disciplines of Medicine and Pathology, University of Sydney, Sydney, New South Wales, Australia
| | - Lars M. Ittner
- Alzheimer's and Parkinson's Disease Laboratory, Brain & Mind Research Institute, University of Sydney, Camperdown, New South Wales, Australia
| | - Hannsjörg Schröder
- Department II of Anatomy and Neuroanatomy, University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, CMMC, University of Cologne, Cologne, Germany
- * E-mail: (HS); (JG)
| | - Jürgen Götz
- Alzheimer's and Parkinson's Disease Laboratory, Brain & Mind Research Institute, University of Sydney, Camperdown, New South Wales, Australia
- * E-mail: (HS); (JG)
| |
Collapse
|
18
|
Targeting hyperphosphorylated tau with sodium selenate suppresses seizures in rodent models. Neurobiol Dis 2012; 45:897-901. [DOI: 10.1016/j.nbd.2011.12.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 11/03/2011] [Accepted: 12/04/2011] [Indexed: 11/18/2022] Open
|
19
|
Vitek MP, Christensen DJ, Wilcock D, Davis J, Van Nostrand WE, Li FQ, Colton CA. APOE-mimetic peptides reduce behavioral deficits, plaques and tangles in Alzheimer's disease transgenics. NEURODEGENER DIS 2012; 10:122-6. [PMID: 22326991 DOI: 10.1159/000334914] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 11/07/2011] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND After age, the second largest risk factor for Alzheimer's disease (AD) is apolipoprotein E (APOE) genotype, where APOE4 is associated with lower apoE protein levels, more severer brain pathology, enhanced inflammation and disease. Small peptides corresponding to the receptor-binding region of apoE mimic the anti-inflammatory activity of the apoE holoprotein. These apoE mimetics greatly improve behavioral outcomes and neuronal survival in head trauma models that display AD pathology and neuronal loss. OBJECTIVE To determine whether apoE mimetics change behavior, inflammation and pathology in CVND-AD (SwDI-APP/NOS2(-/-)) transgenic mice. METHODS Starting at 9 months, apoE peptides were subcutaneously administered 3 times per week for 3 months followed by behavioral, histochemical and biochemical testing. RESULTS Treatment with apoE mimetics significantly improved behavior while decreasing the inflammatory cytokine IL-6, neurofibrillary tangle-like and amyloid plaque-like structures. Biochemical measures matched the visible pathological results. CONCLUSIONS Treatment with apoE mimetics significantly improved behavior, reduced inflammation and reduced pathology in CVND-AD mice. These improvements are associated with apoE-mimetic-mediated increases in protein phosphatase 2A activity. Testing in additional AD models showed similar benefits, reinforcing this novel mechanism of action of apoE mimetics. These data suggest that the combination of anti-inflammatory and neuroprotective activities of apoE mimetics represents a new generation of potential therapeutics for AD.
Collapse
Affiliation(s)
- M P Vitek
- Cognosci, Inc, Research Triangle Park, NC 27709, USA.
| | | | | | | | | | | | | |
Collapse
|
20
|
Wu J, Lou H, Alerte TNM, Stachowski EK, Chen J, Singleton AB, Hamilton RL, Perez RG. Lewy-like aggregation of α-synuclein reduces protein phosphatase 2A activity in vitro and in vivo. Neuroscience 2012; 207:288-97. [PMID: 22326202 DOI: 10.1016/j.neuroscience.2012.01.028] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 12/07/2011] [Accepted: 01/14/2012] [Indexed: 10/14/2022]
Abstract
α-synuclein (α-Syn) is a chaperone-like protein that is highly implicated in Parkinson's disease (PD) as well as in dementia with Lewy bodies (DLB). Rare forms of PD occur in individuals with mutations of α-Syn or triplication of wild type α-Syn, and in both PD and DLB the intraneuronal inclusions known as Lewy bodies contain aggregated α-Syn that is highly phosphorylated on serine 129. In neuronal cells and in the brains of α-Syn overexpressing transgenic mice, soluble α-Syn stimulates the activity of protein phosphatase 2A (PP2A), a major serine/threonine phosphatase. Serine 129 phosphorylation of α-Syn attenuates its stimulatory effects on PP2A and also accelerates α-Syn aggregation; however, it is unknown if aggregation of α-Syn into Lewy bodies impairs PP2A activity. To assess for this, we measured the impact of α-Syn aggregation on PP2A activity in vitro and in vivo. In cell-free assays, aggregated α-Syn had ∼50% less PP2A stimulatory effects than soluble recombinant α-Syn. Similarly in DLB and α-Syn triplication brains, which contain robust α-Syn aggregation with high levels of serine 129 phosphorylation, PP2A activity was also ∼50% attenuated. As α-Syn normally stimulates PP2A activity, our data suggest that overexpression of α-Syn or sequestration of α-Syn into Lewy bodies has the potential to alter the phosphorylation state of key PP2A substrates; raising the possibility that all forms of synucleinopathy will benefit from treatments aimed at optimizing PP2A activity.
Collapse
Affiliation(s)
- J Wu
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Braithwaite SP, Stock JB, Lombroso PJ, Nairn AC. Protein phosphatases and Alzheimer's disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 106:343-79. [PMID: 22340724 PMCID: PMC3739963 DOI: 10.1016/b978-0-12-396456-4.00012-2] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Alzheimer's Disease (AD) is characterized by progressive loss of cognitive function, linked to marked neuronal loss. Pathological hallmarks of the disease are the accumulation of the amyloid-β (Aβ) peptide in the form of amyloid plaques and the intracellular formation of neurofibrillary tangles (NFTs). Accumulating evidence supports a key role for protein phosphorylation in both the normal and pathological actions of Aβ as well as the formation of NFTs. NFTs contain hyperphosphorylated forms of the microtubule-binding protein tau, and phosphorylation of tau by several different kinases leads to its aggregation. The protein kinases involved in the generation and/or actions of tau or Aβ are viable drug targets to prevent or alleviate AD pathology. However, it has also been recognized that the protein phosphatases that reverse the actions of these protein kinases are equally important. Here, we review recent advances in our understanding of serine/threonine and tyrosine protein phosphatases in the pathology of AD.
Collapse
|
22
|
ENU mutagenesis screen to establish motor phenotypes in wild-type mice and modifiers of a pre-existing motor phenotype in tau mutant mice. J Biomed Biotechnol 2011; 2011:130947. [PMID: 22219655 PMCID: PMC3246812 DOI: 10.1155/2011/130947] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 11/04/2011] [Indexed: 11/20/2022] Open
Abstract
Modifier screening is a powerful genetic tool. While not widely used in the vertebrate system, we applied these tools to transgenic mouse strains that recapitulate key aspects of Alzheimer's disease (AD), such as tau-expressing mice. These are characterized by a robust pathology including both motor and memory impairment. The phenotype can be modulated by ENU mutagenesis, which results in novel mutant mouse strains and allows identifying the underlying gene/mutation. Here we discuss this strategy in detail. We firstly obtained pedigrees that modify the tau-related motor phenotype, with mapping ongoing. We further obtained transgene-independent motor pedigrees: (i) hyperactive, circling ENU 37 mice with a causal mutation in the Tbx1 gene—the complete knock-out of Tbx1 models DiGeorge Syndrome; (ii) ENU12/301 mice that show sudden jerky movements and tremor constantly; they have a causal mutation in the Kcnq1 gene, modelling aspects of the Romano-Ward and Jervell and Lange-Nielsen syndromes; and (iii) ENU16/069 mice with tremor and hypermetric gait that have a causal mutation in the Mpz (Myelin Protein Zero) gene, modelling Charcot-Marie-Tooth disease type 1 (CMT1B). Together, we provide evidence for a real potential of an ENU mutagenesis to dissect motor functions in wild-type and tau mutant mice.
Collapse
|
23
|
Modes of Aβ toxicity in Alzheimer's disease. Cell Mol Life Sci 2011; 68:3359-75. [PMID: 21706148 PMCID: PMC3181413 DOI: 10.1007/s00018-011-0750-2] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 06/01/2011] [Accepted: 06/06/2011] [Indexed: 12/18/2022]
Abstract
Alzheimer’s disease (AD) is reaching epidemic proportions, yet a cure is not yet available. While the genetic causes of the rare familial inherited forms of AD are understood, the causes of the sporadic forms of the disease are not. Histopathologically, these two forms of AD are indistinguishable: they are characterized by amyloid-β (Aβ) peptide-containing amyloid plaques and tau-containing neurofibrillary tangles. In this review we compare AD to frontotemporal dementia (FTD), a subset of which is characterized by tau deposition in the absence of overt plaques. A host of transgenic animal AD models have been established through the expression of human proteins with pathogenic mutations previously identified in familial AD and FTD. Determining how these mutant proteins cause disease in vivo should contribute to an understanding of the causes of the more frequent sporadic forms. We discuss the insight transgenic animal models have provided into Aβ and tau toxicity, also with regards to mitochondrial function and the crucial role tau plays in mediating Aβ toxicity. We also discuss the role of miRNAs in mediating the toxic effects of the Aβ peptide.
Collapse
|
24
|
Rahmadi A, Steiner N, Münch G. Advanced glycation endproducts as gerontotoxins and biomarkers for carbonyl-based degenerative processes in Alzheimer's disease. Clin Chem Lab Med 2011; 49:385-91. [PMID: 21275816 DOI: 10.1515/cclm.2011.079] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Alzheimer's disease (AD) is the most common dementia disorder of later life. Although there might be various different triggering events in the early stages of the disease, they appear to converge on a few characteristic final pathways in the late stages, characterized by inflammation and neurodegeneration. Here, we review the hypothesis that advanced glycation end products (AGEs), which reflect carbonyl stress, an imbalance between the production of reactive carbonyl compounds and their detoxification, can serve as biomarkers for the progression of disorder. AGE modification may explain many of the neuropathological and biochemical features of AD, such as extensive protein cross-linking shown as amyloid plaques and neurofibrillary tangles, inflammation, oxidative stress and neuronal cell death. Although accumulation of AGEs is a normal feature of aging, it appears to be significantly accelerated in AD. We suggest that higher AGE concentrations in brain tissue and in cerebrospinal fluid might be able to distinguish between normal aging and AD.
Collapse
Affiliation(s)
- Anton Rahmadi
- Department of Pharmacology, School of Medicine, University of Western Sydney, Campbelltown, Australia
| | | | | |
Collapse
|
25
|
Götz J, Gladbach A, Pennanen L, van Eersel J, Schild A, David D, Ittner LM. Animal models reveal role for tau phosphorylation in human disease. Biochim Biophys Acta Mol Basis Dis 2010; 1802:860-71. [DOI: 10.1016/j.bbadis.2009.09.008] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 09/03/2009] [Accepted: 09/07/2009] [Indexed: 12/18/2022]
|
26
|
van Eersel J, Ke YD, Liu X, Delerue F, Kril JJ, Götz J, Ittner LM. Sodium selenate mitigates tau pathology, neurodegeneration, and functional deficits in Alzheimer's disease models. Proc Natl Acad Sci U S A 2010; 107:13888-93. [PMID: 20643941 PMCID: PMC2922247 DOI: 10.1073/pnas.1009038107] [Citation(s) in RCA: 209] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Alzheimer's disease (AD) brains are characterized by amyloid-beta-containing plaques and hyperphosphorylated tau-containing neurofibrillary tangles (NFTs); however, in frontotemporal dementia, the tau pathology manifests in the absence of overt amyloid-beta plaques. Therapeutic strategies so far have primarily been targeting amyloid-beta, although those targeting tau are only slowly beginning to emerge. Here, we identify sodium selenate as a compound that reduces tau phosphorylation both in vitro and in vivo. Importantly, chronic oral treatment of two independent tau transgenic mouse strains with NFT pathology, P301L mutant pR5 and K369I mutant K3 mice, reduces tau hyperphosphorylation and completely abrogates NFT formation. Furthermore, treatment improves contextual memory and motor performance, and prevents neurodegeneration. As hyperphosphorylation of tau precedes NFT formation, the effect of selenate on tau phosphorylation was assessed in more detail, a process regulated by both kinases and phosphatases. A major phosphatase implicated in tau dephosphorylation is the serine/threonine-specific protein phosphatase 2A (PP2A) that is reduced in both levels and activity in the AD brain. We found that selenate stabilizes PP2A-tau complexes. Moreover, there was an absence of therapeutic effects in sodium selenate-treated tau transgenic mice that coexpress a dominant-negative mutant form of PP2A, suggesting a mediating role for PP2A. Taken together, sodium selenate mitigates tau pathology in several AD models, making it a promising lead compound for tau-targeted treatments of AD and related dementias.
Collapse
Affiliation(s)
- Janet van Eersel
- Alzheimer's and Parkinson's Disease Laboratory, Brain and Mind Research Institute, University of Sydney, Camperdown, New South Wales 2050, Australia; and
- Department of Pathology, University of Sydney, Camperdown, New South Wales 2016, Australia
| | - Yazi D. Ke
- Alzheimer's and Parkinson's Disease Laboratory, Brain and Mind Research Institute, University of Sydney, Camperdown, New South Wales 2050, Australia; and
| | - Xin Liu
- Alzheimer's and Parkinson's Disease Laboratory, Brain and Mind Research Institute, University of Sydney, Camperdown, New South Wales 2050, Australia; and
| | - Fabien Delerue
- Alzheimer's and Parkinson's Disease Laboratory, Brain and Mind Research Institute, University of Sydney, Camperdown, New South Wales 2050, Australia; and
| | - Jillian J. Kril
- Department of Pathology, University of Sydney, Camperdown, New South Wales 2016, Australia
| | - Jürgen Götz
- Alzheimer's and Parkinson's Disease Laboratory, Brain and Mind Research Institute, University of Sydney, Camperdown, New South Wales 2050, Australia; and
| | - Lars M. Ittner
- Alzheimer's and Parkinson's Disease Laboratory, Brain and Mind Research Institute, University of Sydney, Camperdown, New South Wales 2050, Australia; and
| |
Collapse
|
27
|
Medeiros R, Baglietto-Vargas D, LaFerla FM. The role of tau in Alzheimer's disease and related disorders. CNS Neurosci Ther 2010; 17:514-24. [PMID: 20553310 DOI: 10.1111/j.1755-5949.2010.00177.x] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Tau, the microtubule-associated protein, forms insoluble filaments that accumulate as neurofibrillary tangles in Alzheimer's disease (AD) and related tauopathies. Under physiological conditions, tau regulates the assembly and maintenance of the structural stability of microtubules. In the diseased brain, however, tau becomes abnormally hyperphosphorylated, which ultimately causes the microtubules to disassemble, and the free tau molecules aggregate into paired helical filaments. A large body of evidence suggests that tau hyperphosphorylation results from perturbation of cellular signaling, mainly through imbalance in the activities of different protein kinases and phosphatases. In AD, it appears that ß-amyloid peptide (Aß) plays a pivotal role in triggering this imbalance. In this review, we summarize our current understanding of the role of tau in AD and other tauopathies, and highlight key issues that need to be addressed to improve the success of developing novel therapies.
Collapse
Affiliation(s)
- Rodrigo Medeiros
- Department of Neurobiology and Behavior and Institute for Memory Impairments and Neurological Disorders, University of California, Irvine, CA, USA
| | | | | |
Collapse
|
28
|
Bialopiotrowicz E, Kuzniewska B, Kachamakova-Trojanowska N, Barcikowska M, Kuznicki J, Wojda U. Cell cycle regulation distinguishes lymphocytes from sporadic and familial Alzheimer's disease patients. Neurobiol Aging 2010; 32:2319.e13-26. [PMID: 20541838 DOI: 10.1016/j.neurobiolaging.2010.04.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 03/16/2010] [Accepted: 04/20/2010] [Indexed: 12/12/2022]
Abstract
Cell cycle (CC) reactivation in neurons seems to underlie the development of Alzheimer's disease (AD). We analyzed whether CC alterations can be detected in immortalized lymphocytes from patients with the sporadic and the familial form of AD (SAD and FAD). Real-time polymerase chain reaction (PCR)-arrays, immunoblotting, and flow cytometry demonstrated differences in the regulation of G1/S phases between SAD lymphocytes and cells from nondemented subjects, as well as between SAD and FAD cells. SAD compared to FAD lymphocytes showed differences in expression profiles of the 90 CC genes, and a marked increase in the level of the p21 protein, which promotes G1-arrest. Accordingly, SAD but not FAD cells had a prolonged G1-phase. γ-secretase inhibition did not change the CC profiles of the cell lines. These data show that SAD involves a prolongation of the G1 phase driven by p21 pathway, which is not activated in FAD cells. Thus, the mechanism in SAD differs from FAD. Moreover, disturbances of the CC in lymphocytes have a potential diagnostic value.
Collapse
Affiliation(s)
- Emilia Bialopiotrowicz
- Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | | | | | | | | | | |
Collapse
|
29
|
Abstract
In dementia research, animal models have become indispensable tools. They not only model aspects of the human condition, but also simulate processes that occur in humans and hence provide insight into how disease is initiated and propagated. The present review discusses two prominent human neurodegenerative disorders, Alzheimer's disease and frontotemporal dementia. It discusses what we would like to model in animals and highlights some of the more recent achievements using species as diverse as mice, fish, flies and worms. Advances in imaging and therapy are explored. We also discuss some anticipated new models and developments. These will reveal how key players in the pathogenesis of Alzheimer's disease and frontotemporal dementia, such as the peptide Aβ (amyloid β) and the protein tau, cause neuronal dysfunction and eventually, neuronal demise. Understanding these processes fully will lead to early diagnosis and therapy.
Collapse
|