1
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Granholm AC, Hamlett ED. The Role of Tau Pathology in Alzheimer's Disease and Down Syndrome. J Clin Med 2024; 13:1338. [PMID: 38592182 PMCID: PMC10932364 DOI: 10.3390/jcm13051338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 02/10/2024] [Accepted: 02/20/2024] [Indexed: 04/10/2024] Open
Abstract
Background: Individuals with Down syndrome (DS) exhibit an almost complete penetrance of Alzheimer's disease (AD) pathology but are underrepresented in clinical trials for AD. The Tau protein is associated with microtubule function in the neuron and is crucial for normal axonal transport. In several different neurodegenerative disorders, Tau misfolding leads to hyper-phosphorylation of Tau (p-Tau), which may seed pathology to bystander cells and spread. This review is focused on current findings regarding p-Tau and its potential to seed pathology as a "prion-like" spreader. It also considers the consequences of p-Tau pathology leading to AD, particularly in individuals with Down syndrome. Methods: Scopus (SC) and PubMed (PM) were searched in English using keywords "tau AND seeding AND brain AND down syndrome". A total of 558 SC or 529 PM potentially relevant articles were identified, of which only six SC or three PM articles mentioned Down syndrome. This review was built upon the literature and the recent findings of our group and others. Results: Misfolded p-Tau isoforms are seeding competent and may be responsible for spreading AD pathology. Conclusions: This review demonstrates recent work focused on understanding the role of neurofibrillary tangles and monomeric/oligomeric Tau in the prion-like spreading of Tau pathology in the human brain.
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Affiliation(s)
- Ann-Charlotte Granholm
- Department of Neurosurgery, University of Colorado Anschutz Medical Center, Aurora, CO 80045, USA
| | - Eric D. Hamlett
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29425, USA;
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2
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Maina MB, Al-Hilaly YK, Serpell LC. Dityrosine cross-linking and its potential roles in Alzheimer's disease. Front Neurosci 2023; 17:1132670. [PMID: 37034163 PMCID: PMC10075315 DOI: 10.3389/fnins.2023.1132670] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 03/01/2023] [Indexed: 04/11/2023] Open
Abstract
Oxidative stress is a significant source of damage that accumulates during aging and contributes to Alzheimer's disease (AD) pathogenesis. Oxidation of proteins can give rise to covalent links between adjacent tyrosines known as dityrosine (DiY) cross-linking, amongst other modifications, and this observation suggests that DiY could serve as a biomarker of accumulated oxidative stress over the lifespan. Many studies have focused on understanding the contribution of DiY to AD pathogenesis and have revealed that DiY crosslinks can be found in both Aβ and tau deposits - the two key proteins involved in the formation of amyloid plaques and tau tangles, respectively. However, there is no consensus yet in the field on the impact of DiY on Aβ and tau function, aggregation, and toxicity. Here we review the current understanding of the role of DiY on Aβ and tau gathered over the last 20 years since the first observation, and discuss the effect of this modification for Aβ and tau aggregation, and its potential as a biomarker for AD.
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Affiliation(s)
- Mahmoud B. Maina
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, United Kingdom
- Biomedical Science Research and Training Centre, College of Medical Sciences, Yobe State University, Damaturu, Nigeria
| | - Youssra K. Al-Hilaly
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, United Kingdom
- Department of Chemistry, College of Science, Mustansiriyah University, Baghdad, Iraq
| | - Louise C. Serpell
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, United Kingdom
- *Correspondence: Louise C. Serpell,
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3
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Yang C, Zhao X, An X, Zhang Y, Sun W, Zhang Y, Duan Y, Kang X, Sun Y, Jiang L, Lian F. Axonal transport deficits in the pathogenesis of diabetic peripheral neuropathy. Front Endocrinol (Lausanne) 2023; 14:1136796. [PMID: 37056668 PMCID: PMC10086245 DOI: 10.3389/fendo.2023.1136796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
Diabetic peripheral neuropathy (DPN) is a chronic and prevalent metabolic disease that gravely endangers human health and seriously affects the quality of life of hyperglycemic patients. More seriously, it can lead to amputation and neuropathic pain, imposing a severe financial burden on patients and the healthcare system. Even with strict glycemic control or pancreas transplantation, peripheral nerve damage is difficult to reverse. Most current treatment options for DPN can only treat the symptoms but not the underlying mechanism. Patients with long-term diabetes mellitus (DM) develop axonal transport dysfunction, which could be an important factor in causing or exacerbating DPN. This review explores the underlying mechanisms that may be related to axonal transport impairment and cytoskeletal changes caused by DM, and the relevance of the latter with the occurrence and progression of DPN, including nerve fiber loss, diminished nerve conduction velocity, and impaired nerve regeneration, and also predicts possible therapeutic strategies. Understanding the mechanisms of diabetic neuronal injury is essential to prevent the deterioration of DPN and to develop new therapeutic strategies. Timely and effective improvement of axonal transport impairment is particularly critical for the treatment of peripheral neuropathies.
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4
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Fischer I. Evolutionary perspective of Big tau structure: 4a exon variants of MAPT. Front Mol Neurosci 2022; 15:1019999. [PMID: 36533137 PMCID: PMC9755724 DOI: 10.3389/fnmol.2022.1019999] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 10/17/2022] [Indexed: 08/15/2023] Open
Abstract
The MAPT gene encoding the microtubule-associated protein tau can generate multiple isoforms by alternative splicing giving rise to proteins which are differentially expressed in specific areas of the nervous system and at different developmental stages. Tau plays important roles in modulating microtubule dynamics, axonal transport, synaptic plasticity, and DNA repair, and has also been associated with neurodegenerative diseases (tauopathies) including Alzheimer's disease and frontotemporal dementia. A unique high-molecular-weight isoform of tau, originally found to be expressed in the peripheral nervous system and projecting neurons, has been termed Big tau and has been shown to uniquely contain the large exon 4a that significantly increases the size and 3D structure of tau. With little progress since the original discovery of Big tau, more than 25 years ago, we have now completed a comprehensive comparative study to analyze the structure of the MAPT gene against available databases with respect to the composition of the tau exons as they evolved from early vertebrates to primates and human. We focused the analysis on the evolution of the 4a exon variants and their homology relative to humans. We discovered that the 4a exon defining Big tau appears to be present early in vertebrate evolution as a large insert that dramatically changed the size of the tau protein with low sequence conservation despite a stable size range of about 250aa, and in some species a larger 4a-L exon of 355aa. We suggest that 4a exon variants evolved independently in different species by an exonization process using new alternative splicing to address the growing complexities of the evolving nervous systems. Thus, the appearance of a significantly larger isoform of tau independently repeated itself multiple times during evolution, accentuating the need across vertebrate species for an elongated domain that likely endows Big tau with novel physiological functions as well as properties related to neurodegeneration.
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Affiliation(s)
- Itzhak Fischer
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States
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5
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Bell M, Zempel H. SH-SY5Y-derived neurons: a human neuronal model system for investigating TAU sorting and neuronal subtype-specific TAU vulnerability. Rev Neurosci 2021; 33:1-15. [PMID: 33866701 DOI: 10.1515/revneuro-2020-0152] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 03/06/2021] [Indexed: 11/15/2022]
Abstract
The microtubule-associated protein (MAP) TAU is mainly sorted into the axon of healthy brain neurons. Somatodendritic missorting of TAU is a pathological hallmark of many neurodegenerative diseases, including Alzheimer's disease (AD). Cause, consequence and (patho)physiological mechanisms of TAU sorting and missorting are understudied, in part also because of the lack of readily available human neuronal model systems. The human neuroblastoma cell line SH-SY5Y is widely used for studying TAU physiology and TAU-related pathology in AD and related tauopathies. SH-SY5Y cells can be differentiated into neuron-like cells (SH-SY5Y-derived neurons) using various substances. This review evaluates whether SH-SY5Y-derived neurons are a suitable model for (i) investigating intracellular TAU sorting in general, and (ii) with respect to neuron subtype-specific TAU vulnerability. (I) SH-SY5Y-derived neurons show pronounced axodendritic polarity, high levels of axonally localized TAU protein, expression of all six human brain isoforms and TAU phosphorylation similar to the human brain. As SH-SY5Y cells are highly proliferative and readily accessible for genetic engineering, stable transgene integration and leading-edge genome editing are feasible. (II) SH-SY5Y-derived neurons display features of subcortical neurons early affected in many tauopathies. This allows analyzing brain region-specific differences in TAU physiology, also in the context of differential vulnerability to TAU pathology. However, several limitations should be considered when using SH-SY5Y-derived neurons, e.g., the lack of clearly defined neuronal subtypes, or the difficulty of mimicking age-related tauopathy risk factors in vitro. In brief, this review discusses the suitability of SH-SY5Y-derived neurons for investigating TAU (mis)sorting mechanisms and neuron-specific TAU vulnerability in disease paradigms.
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Affiliation(s)
- Michael Bell
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 34, 50931Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, 50931Cologne, Germany
| | - Hans Zempel
- Institute of Human Genetics, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 34, 50931Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, 50931Cologne, Germany
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6
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Sidoryk-Wegrzynowicz M, Strużyńska L. Dysfunctional glia: contributors to neurodegenerative disorders. Neural Regen Res 2021; 16:218-222. [PMID: 32859767 PMCID: PMC7896233 DOI: 10.4103/1673-5374.290877] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Astrocytes are integral components of the central nervous system, where they are involved in numerous functions critical for neuronal development and functioning, including maintenance of blood-brain barrier, formation of synapses, supporting neurons with nutrients and trophic factors, and protecting them from injury. These roles are markedly affected in the course of chronic neurodegenerative disorders, often before the onset of the disease. In this review, we summarize the recent findings supporting the hypothesis that astrocytes play a fundamental role in the processes contributing to neurodegeneration. We focus on α-synucleinopathies and tauopathies as the most common neurodegenerative diseases. The mechanisms implicated in the development and progression of these disorders appear not to be exclusively neuronal, but are often related to the astrocytic-neuronal integrity and the response of astrocytes to the altered microglial function. A profound understanding of the multifaceted functions of astrocytes and identification of their communication pathways with neurons and microglia in health and in the disease is of critical significance for the development of novel mechanism-based therapies against neurodegenerative disorders.
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Affiliation(s)
- Marta Sidoryk-Wegrzynowicz
- Laboratory of Pathoneurochemistry, Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Lidia Strużyńska
- Laboratory of Pathoneurochemistry, Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
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7
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Oakley SS, Maina MB, Marshall KE, Al-Hilaly YK, Harrington CR, Wischik CM, Serpell LC. Tau Filament Self-Assembly and Structure: Tau as a Therapeutic Target. Front Neurol 2020; 11:590754. [PMID: 33281730 PMCID: PMC7688747 DOI: 10.3389/fneur.2020.590754] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 09/04/2020] [Indexed: 12/12/2022] Open
Abstract
Tau plays an important pathological role in a group of neurodegenerative diseases called tauopathies, including Alzheimer's disease, Pick's disease, chronic traumatic encephalopathy and corticobasal degeneration. In each disease, tau self-assembles abnormally to form filaments that deposit in the brain. Tau is a natively unfolded protein that can adopt distinct structures in different pathological disorders. Cryo-electron microscopy has recently provided a series of structures for the core of the filaments purified from brain tissue from patients with different tauopathies and revealed that they share a common core region, while differing in their specific conformation. This structurally resolvable part of the core is contained within a proteolytically stable core region from the repeat domain initially isolated from AD tau filaments. Tau has recently become an important target for therapy. Recent work has suggested that the prevention of tau self-assembly may be effective in slowing the progression of Alzheimer's disease and other tauopathies. Here we review the work that explores the importance of tau filament structures and tau self-assembly mechanisms, as well as examining model systems that permit the exploration of the mode of action of potential inhibitors.
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Affiliation(s)
- Sebastian S. Oakley
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Mahmoud B. Maina
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- College of Medical Sciences, Yobe State University, Damaturu, Nigeria
| | - Karen E. Marshall
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Youssra K. Al-Hilaly
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
- Chemistry Department, College of Science, Mustansiriyah University, Baghdad, Iraq
| | - Charlie R. Harrington
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, United Kingdom
- TauRx Therapeutics Ltd., Aberdeen, United Kingdom
| | - Claude M. Wischik
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, United Kingdom
- TauRx Therapeutics Ltd., Aberdeen, United Kingdom
| | - Louise C. Serpell
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Brighton, United Kingdom
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8
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Brandt R, Trushina NI, Bakota L. Much More Than a Cytoskeletal Protein: Physiological and Pathological Functions of the Non-microtubule Binding Region of Tau. Front Neurol 2020; 11:590059. [PMID: 33193056 PMCID: PMC7604284 DOI: 10.3389/fneur.2020.590059] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 09/16/2020] [Indexed: 12/21/2022] Open
Abstract
Tau protein (MAPT) is classified as a microtubule-associated protein (MAP) and is believed to regulate the axonal microtubule arrangement. It belongs to the tau/MAP2/MAP4 family of MAPs that have a similar microtubule binding region at their carboxy-terminal half. In tauopathies, such as Alzheimer's disease, tau is distributed more in the somatodendritic compartment, where it aggregates into filamentous structures, the formation of which correlates with cognitive impairments in patients. While microtubules are the dominant interaction partners of tau under physiological conditions, tau has many additional interaction partners that can contribute to its physiological and pathological role. In particular, the amino-terminal non-microtubule binding domain (N-terminal projection region, NTR) of tau interacts with many partners that are involved in membrane organization. The NTR contains intrinsically disordered regions (IDRs) that show a strong evolutionary increase in the disorder and may have been the basis for the development of new, tau-specific interactions. In this review we discuss the functional organization of the tau protein and the special features of the tau non-microtubule binding region also in the connection with the results of Tau KO models. We consider possible physiological and pathological functions of tau's non-microtubule interactions, which could indicate that interactions mediated by tau's NTR and regulated by far-reaching functional interactions of the PRR and the extreme C-terminus of tau contribute to the pathological processes.
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Affiliation(s)
- Roland Brandt
- Department of Neurobiology, University of Osnabrück, Osnabrück, Germany.,Center for Cellular Nanoanalytics, University of Osnabrück, Osnabrück, Germany.,Institute of Cognitive Science, University of Osnabrück, Osnabrück, Germany
| | | | - Lidia Bakota
- Department of Neurobiology, University of Osnabrück, Osnabrück, Germany
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9
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Tubulin modifying enzymes as target for the treatment oftau-related diseases. Pharmacol Ther 2020; 218:107681. [PMID: 32961263 DOI: 10.1016/j.pharmthera.2020.107681] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 09/09/2020] [Indexed: 01/17/2023]
Abstract
In the brain of patients with Alzheimer's disease (AD), the number and length of microtubules (MTs) are significantly and selectively reduced. MTs are involved in a wide range of cellular functions, and defects of the microtubular system have emerged as a unifying hypothesis for the heterogeneous and variable clinical presentations of AD. MTs orchestrate their numerous functions through the spatiotemporal regulation of the binding of specialised microtubule-associated proteins (MAPs) and molecular motors. Covalent posttranslational modifications (PTMs) on the tubulin C-termini that protrude at the surface of MTs regulate the binding of these effectors. In neurons, MAP tau is highly abundant and its abnormal dissociation from MTs in the axon, cellular mislocalization and hyperphosphorylation, are primary events leading to neuronal death. Consequently, compounds targeting tau phosphorylation or aggregation are currently evaluated but their clinical significance has not been demonstrated yet. In this review, we discuss the emerging link between tubulin PTMs and tau dysfunction. In neurons, high levels of glutamylation and detyrosination profoundly impact the physicochemical properties at the surface of MTs. Moreover, in patients with early-onset progressive neurodegeneration, deleterious mutations in enzymes involved in modifying MTs at the surface have recently been identified, underscoring the importance of this enzymatic machinery in neurology. We postulate that pharmacologically targeting the tubulin-modifying enzymes holds promise as therapeutic approach for the treatment of neurodegenerative diseases.
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10
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Kamata S, Hashiyama R, Hana-Ika H, Ohkubo I, Saito R, Honda A, Anan Y, Akahoshi N, Noguchi K, Kanda Y, Ishii I. Cytotoxicity comparison of 35 developmental neurotoxicants in human induced pluripotent stem cells (iPSC), iPSC-derived neural progenitor cells, and transformed cell lines. Toxicol In Vitro 2020; 69:104999. [PMID: 32949729 DOI: 10.1016/j.tiv.2020.104999] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 08/05/2020] [Accepted: 09/09/2020] [Indexed: 11/27/2022]
Abstract
The Organization for Economic Co-operation and Development (OECD) test guideline 426 for developmental neurotoxicity (DNT) of industrial/environmental chemicals depends primarily on animal experimentation. This requirement raises various critical issues, such as high cost, long duration, the sacrifice of large numbers of animals, and interspecies differences. This study demonstrates an alternative protocol that is simple, quick, less expensive, and standardized to evaluate DNT of many chemicals using human induced pluripotent stem cells (iPSC) and their differentiation to neural progenitor cells (NPC). Initially, concentration-dependent cytotoxicity of 35 DNT chemicals, including industrial materials, insecticides, and clinical drugs, were compared among iPSC, NPC, and two transformed cells, Cos-7 and HepG2, using tetrazolium dye (MTS)-reducing colorimetric and ATP luciferase assays, and IC50 values were calculated. Next, inhibitory effects of the 14 representative chemicals (mainly insecticides) on iPSC differentiation to NPC were evaluated by measuring altered expression of neural differentiation and undifferentiation marker genes. Results show that both iPSC and NPC were much more sensitive to most DNT chemicals than the transformed cells, and 14 chemicals induced differential patterns of marker gene expression, highlighting the validity and utility of the protocol for evaluation and classification of DNT chemicals and preclinical DNT tests for safety assessment.
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Affiliation(s)
- Shotaro Kamata
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Reina Hashiyama
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Hiroto Hana-Ika
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Issei Ohkubo
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Ryota Saito
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Akihiro Honda
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Yasumi Anan
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Noriyuki Akahoshi
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Kohji Noguchi
- Laboratory of Molecular Target Therapy, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Yasunari Kanda
- Division of Pharmacology, National Institute of Health Sciences, Kawasaki, Kanagawa 210-9501, Japan.
| | - Isao Ishii
- Department of Health Chemistry, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan.
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11
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Dell'Orco M, Oliver RJ, Perrone-Bizzozero N. HuD Binds to and Regulates Circular RNAs Derived From Neuronal Development- and Synaptic Plasticity-Associated Genes. Front Genet 2020; 11:790. [PMID: 32849796 PMCID: PMC7419605 DOI: 10.3389/fgene.2020.00790] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Accepted: 07/03/2020] [Indexed: 12/17/2022] Open
Abstract
The RNA-binding protein (RBP) HuD is involved in neuronal differentiation, regeneration, synaptic plasticity and learning and memory. RBPs not only bind to mRNAs but also interact with several types of RNAs including circular RNAs (circRNAs), a class of non-coding RNAs generated by pre-mRNA back-splicing. This study explored whether HuD could regulate the expression of neuronal circRNAs. HuD controls target RNA’s fate by binding to Adenylate-Uridylate Rich Elements (AREs). Using bioinformatics analyses, we found HuD-binding ARE-motifs in about 26% of brain-expressed circRNAs. By RNA immunoprecipitation (RIP) from the mouse striatum followed by circRNA arrays, we identified over 600 circRNAs bound to HuD. Among these, 226 derived from genes where HuD also bound to their associated mRNAs including circHomer1a, which we previously characterized as a synaptic HuD target circRNA. Binding of HuD to two additional plasticity–associated circRNAs, circCreb1, and circUfp2, was validated by circRNA-specific qRT-PCR. Interestingly, we found that circUpf2 is also enriched in synaptosomes. Pathway analyses confirmed that the majority of HuD-bound circRNAs originate from genes regulating nervous system development and function. Using striatal tissues from HuD overexpressor (HuD-OE) and knock out (KO) mice for circRNA expression analyses we identified 86 HuD-regulated circRNAs. These derived from genes within the same biological pathways as the HuD RIP. Cross-correlation analyses of HuD-regulated and HuD-bound circRNAs identified 69 regulated in either HuD-OE or HuD-KO and 5 in both sets. These include circBrwd1, circFoxp1, and circMap1a, which derive from genes involved in neuronal development and regeneration, and circMagi1 and circLppr4, originating from genes controlling synapse formation and linked to psychiatric disorders. These circRNAs form competing endogenous RNA (ceRNA) networks including microRNAs and mRNAs. Among the HuD target circRNAs, circBrwd1 and circFoxp1 are regulated in an opposite manner to their respective mRNAs. The expressions of other development- and plasticity-associated HuD target circRNAs such as circSatb2, cirHomer1a and circNtrk3 are also altered after the establishment of cocaine conditioned place preference (CPP). Collectively, these data suggest that HuD interactions with circRNAs regulate their expression and transport, and that the ensuing changes in HuD-regulated ceRNA networks could control neuronal differentiation and synaptic plasticity.
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Affiliation(s)
- Michela Dell'Orco
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, United States
| | - Robert J Oliver
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, United States
| | - Nora Perrone-Bizzozero
- Department of Neurosciences, School of Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM, United States
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12
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Astroglial contribution to tau-dependent neurodegeneration. Biochem J 2020; 476:3493-3504. [PMID: 31774919 DOI: 10.1042/bcj20190506] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 11/07/2019] [Accepted: 11/08/2019] [Indexed: 01/31/2023]
Abstract
Astrocytes, by maintaining an optimal environment for neuronal function, play a critical role in proper function of mammalian nervous system. They regulate synaptic transmission and plasticity and protect neurons against toxic insults. Astrocytes and neurons interact actively via glutamine-glutamate cycle (GGC) that supports neuronal metabolic demands and neurotransmission. GGC deficiency may be involved in different diseases of the brain, where impaired astrocytic control of glutamate homeostasis contributes to neuronal dysfunction. This includes tau-dependent neurodegeneration, where astrocytes lose key molecules involved in regulation of glutamate/glutamine homeostasis, neuronal survival and synaptogenesis. Astrocytic dysfunction in tauopathy appears to precede neurodegeneration and overt tau neuropathology such as phosphorylation, aggregation and formation of neurofibrillary tangles. In this review, we summarize recent studies demonstrating that activation of astrocytes is strictly associated with neurodegenerative processes including those involved in tau related pathology. We propose that astrocytic dysfunction, by disrupting the proper neuron-glia signalling early in the disease, significantly contributes to tauopathy pathogenesis.
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13
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Fischer I, Baas PW. Resurrecting the Mysteries of Big Tau. Trends Neurosci 2020; 43:493-504. [PMID: 32434664 DOI: 10.1016/j.tins.2020.04.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 03/28/2020] [Accepted: 04/20/2020] [Indexed: 12/16/2022]
Abstract
Tau, a microtubule-associated protein that modifies the dynamic properties and organization of microtubules in neurons and affects axonal transport, shows remarkable heterogeneity, with multiple isoforms (45-65 kDa) generated by alternative splicing. A high-molecular-weight (HMW) isoform (110 kDa) that contains an additional large exon termed 4a was discovered more than 25 years ago. This isoform, called Big tau, is expressed mainly in the adult peripheral nervous system (PNS), but also in adult neurons of the central nervous system (CNS) that extend processes into the periphery. Surprisingly little has been learned about Big tau since its initial characterization, leaving a significant gap in knowledge about how the dramatic switch to Big tau affects the properties of neurons in the context of development, disease, or injury. Here we review what was learned about the structure and distribution of Big tau in those earlier studies, and add contemporary insights to resurrect interest in the mysteries of Big tau and thereby set a path for future studies.
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Affiliation(s)
- Itzhak Fischer
- Drexel University College of Medicine, Department of Neurobiology and Anatomy, 2900 Queen Lane, Philadelphia, PA 19129, USA.
| | - Peter W Baas
- Drexel University College of Medicine, Department of Neurobiology and Anatomy, 2900 Queen Lane, Philadelphia, PA 19129, USA.
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14
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Yi S, Liu Q, Wang X, Qian T, Wang H, Zha G, Yu J, Wang P, Gu X, Chu D, Li S. Tau modulates Schwann cell proliferation, migration and differentiation following peripheral nerve injury. J Cell Sci 2019; 132:jcs.222059. [PMID: 30782778 DOI: 10.1242/jcs.222059] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 01/22/2019] [Indexed: 12/14/2022] Open
Abstract
Tau protein (encoded by the gene microtubule-associated protein tau, Mapt) is essential for the assembly and stability of microtubule and the functional maintenance of the nervous system. Tau is highly abundant in neurons and is detectable in astrocytes and oligodendrocytes. However, whether tau is present in Schwann cells, the unique glial cells in the peripheral nervous system, is unclear. Here, we investigated the presence of tau and its coding mRNA, Mapt, in cultured Schwann cells and find that tau is present in these cells. Gene silencing of Mapt promoted Schwann cell proliferation and inhibited Schwann cell migration and differentiation. In vivo application of Mapt siRNA suppressed the migration of Schwann cells after sciatic nerve injury. Consistent with this, Mapt-knockout mice showed elevated proliferation and reduced migration of Schwann cells. Rats injected with Mapt siRNA and Mapt-knockout mice also exhibited impaired myelin and lipid debris clearance. The expression and distribution of the cytoskeleton proteins α-tubulin and F-actin were also disrupted in these animals. These findings demonstrate the existence and biological effects of tau in Schwann cells, and expand our understanding of the function of tau in the nervous system.
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Affiliation(s)
- Sheng Yi
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Qianyan Liu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Xinghui Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Tianmei Qian
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Hongkui Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Guangbin Zha
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Jun Yu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Pan Wang
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Xiaosong Gu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Dandan Chu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Shiying Li
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
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Castellani RJ, Perry G. Tau Biology, Tauopathy, Traumatic Brain Injury, and Diagnostic Challenges. J Alzheimers Dis 2019; 67:447-467. [PMID: 30584140 PMCID: PMC6398540 DOI: 10.3233/jad-180721] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2018] [Indexed: 12/12/2022]
Abstract
There is considerable interest in the pathobiology of tau protein, given its potential role in neurodegenerative diseases and aging. Tau is an important microtubule associated protein, required for the assembly of tubulin into microtubules and maintaining structural integrity of axons. Tau has other diverse cellular functions involving signal transduction, cellular proliferation, developmental neurobiology, neuroplasticity, and synaptic activity. Alternative splicing results in tau isoforms with differing microtubule binding affinity, differing representation in pathological inclusions in certain disease states, and differing roles in developmental biology and homeostasis. Tau haplotypes confer differing susceptibility to neurodegeneration. Tau phosphorylation is a normal metabolic process, critical in controlling tau's binding to microtubules, and is ongoing within the brain at all times. Tau may be hyperphosphorylated, and may aggregate as detectable fibrillar deposits in tissues, in both aging and neurodegenerative disease. The hypothesis that p-tau is neurotoxic has prompted constructs related to isomers, low-n assembly intermediates or oligomers, and the "tau prion". Human postmortem studies have elucidated broad patterns of tauopathy, with tendencies for those patterns to differ as a function of disease phenotype. However, there is extensive overlap, not only between genuine neurodegenerative diseases, but also between aging and disease. Recent studies highlight uniqueness to pathological patterns, including a pattern attributed to repetitive head trauma, although clinical correlations have been elusive. The diagnostic process for tauopathies and neurodegenerative diseases in general is challenging in many respects, and may be particularly problematic for postmortem evaluation of former athletes and military service members.
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Affiliation(s)
- Rudy J. Castellani
- Departments of Pathology and Neuroscience, West Virginia University School of Medicine, Morgantown, WV, USA
| | - George Perry
- College of Sciences, University of Texas, San Antonio, San Antonio, TX, USA
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Sierra-Fonseca JA, Gosselink KL. Tauopathy and neurodegeneration: A role for stress. Neurobiol Stress 2018; 9:105-112. [PMID: 30450376 PMCID: PMC6234266 DOI: 10.1016/j.ynstr.2018.08.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 08/30/2018] [Accepted: 08/31/2018] [Indexed: 01/22/2023] Open
Abstract
Neurodegenerative diseases are characterized by an irreversible and progressive loss of neuronal structure and function. While many alterations to normal cellular processes occur during neurodegeneration, a pathological accumulation of aggregated proteins constitutes a hallmark of several neurodegenerative disorders. Alzheimer's disease, specifically, is pathologically defined by the formation of amyloid plaques and tangles of hyperphosphorylated tau protein. Stress has emerged as an important factor in the development and progression of neurodegenerative diseases, including Alzheimer's. Very little is known, however, regarding the effects of stress on the mechanisms controlling abnormal protein aggregation and clearance. Chronic stress activates the hypothalamic-pituitary-adrenal (HPA) axis, causing an excessive secretion of glucocorticoids that are capable of impacting diverse physiological and cellular processes. The present review focuses on the influence of stress on a key feature of Alzheimer's disease pathology, emphasizing the relationship between tau phosphorylation and accumulation and its connection to HPA axis dysfunction.
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Affiliation(s)
- Jorge A Sierra-Fonseca
- Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, TX, 79968, USA
| | - Kristin L Gosselink
- Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, TX, 79968, USA
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17
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Sotiropoulos I, Galas MC, Silva JM, Skoulakis E, Wegmann S, Maina MB, Blum D, Sayas CL, Mandelkow EM, Mandelkow E, Spillantini MG, Sousa N, Avila J, Medina M, Mudher A, Buee L. Atypical, non-standard functions of the microtubule associated Tau protein. Acta Neuropathol Commun 2017; 5:91. [PMID: 29187252 PMCID: PMC5707803 DOI: 10.1186/s40478-017-0489-6] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/30/2017] [Indexed: 12/21/2022] Open
Abstract
Since the discovery of the microtubule-associated protein Tau (MAPT) over 40 years ago, most studies have focused on Tau's role in microtubule stability and regulation, as well as on the neuropathological consequences of Tau hyperphosphorylation and aggregation in Alzheimer's disease (AD) brains. In recent years, however, research efforts identified new interaction partners and different sub-cellular localizations for Tau suggesting additional roles beyond its standard function as microtubule regulating protein. Moreover, despite the increasing research focus on AD over the last decades, Tau was only recently considered as a promising therapeutic target for the treatment and prevention of AD as well as for neurological pathologies beyond AD e.g. epilepsy, excitotoxicity, and environmental stress. This review will focus on atypical, non-standard roles of Tau on neuronal function and dysfunction in AD and other neurological pathologies providing novel insights about neuroplastic and neuropathological implications of Tau in both the central and the peripheral nervous system.
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Affiliation(s)
- Ioannis Sotiropoulos
- Life and Health Sciences Research Institute (ICVS), Medical School, University of Minho, Braga, Portugal.
- ICVS/3B's - PT Government Associate Laboratory, Guimarães, Braga, Portugal.
| | | | - Joana M Silva
- Life and Health Sciences Research Institute (ICVS), Medical School, University of Minho, Braga, Portugal
- ICVS/3B's - PT Government Associate Laboratory, Guimarães, Braga, Portugal
| | - Efthimios Skoulakis
- Division of Neuroscience, Biomedical Sciences Research Centre "Alexander Fleming", 16672, Vari, Greece
| | - Susanne Wegmann
- Alzheimer's Disease Research Laboratory, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, 02129, USA
| | - Mahmoud Bukar Maina
- School of Life Sciences, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QG, UK
| | - David Blum
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc, 59000, Lille, France
| | - Carmen Laura Sayas
- Centre for Biomedical Research of the Canary Islands (CIBICAN), Institute for Biomedical Technologies (ITB), Universidad de La Laguna (ULL), Tenerife, Spain
| | - Eva-Maria Mandelkow
- DZNE, German Center for Neurodegenerative Diseases, Bonn, Germany; CAESAR Research Institute, Bonn, Germany; Max-Planck-Institute for Metabolism Research, Köln, Germany
| | - Eckhard Mandelkow
- DZNE, German Center for Neurodegenerative Diseases, Bonn, Germany; CAESAR Research Institute, Bonn, Germany; Max-Planck-Institute for Metabolism Research, Köln, Germany
| | | | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), Medical School, University of Minho, Braga, Portugal
- ICVS/3B's - PT Government Associate Laboratory, Guimarães, Braga, Portugal
| | - Jesus Avila
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Valderrebollo 5, 28041, Madrid, Spain
- Centro de Biología Molecular "Severo Ochoa" CSIC-UAM, Universidad Autónoma de Madrid, C/ Nicolás Cabrera 1, 28049, Madrid, Spain
| | - Miguel Medina
- CIBERNED, Network Center for Biomedical Research in Neurodegenerative Diseases, Madrid, Spain
- CIEN Foundation, Queen Sofia Foundation Alzheimer Center, Madrid, Spain
| | - Amrit Mudher
- Faculty of Natural and Environmental Sciences, University of Southampton Highfield Campus, Center for Biological Sciences, Southampton, UK
| | - Luc Buee
- Univ. Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc, 59000, Lille, France
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18
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Analysis of gene expression in the nervous system identifies key genes and novel candidates for health and disease. Neurogenetics 2017; 18:81-95. [PMID: 28190221 PMCID: PMC5359387 DOI: 10.1007/s10048-017-0509-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 01/20/2017] [Indexed: 01/09/2023]
Abstract
The incidence of neurodegenerative diseases in the developed world has risen over the last century, concomitant with an increase in average human lifespan. A major challenge is therefore to identify genes that control neuronal health and viability with a view to enhancing neuronal health during ageing and reducing the burden of neurodegeneration. Analysis of gene expression data has recently been used to infer gene functions for a range of tissues from co-expression networks. We have now applied this approach to transcriptomic datasets from the mammalian nervous system available in the public domain. We have defined the genes critical for influencing neuronal health and disease in different neurological cell types and brain regions. The functional contribution of genes in each co-expression cluster was validated using human disease and knockout mouse phenotypes, pathways and gene ontology term annotation. Additionally a number of poorly annotated genes were implicated by this approach in nervous system function. Exploiting gene expression data available in the public domain allowed us to validate key nervous system genes and, importantly, to identify additional genes with minimal functional annotation but with the same expression pattern. These genes are thus novel candidates for a role in neurological health and disease and could now be further investigated to confirm their function and regulation during ageing and neurodegeneration.
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19
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Arendt T, Stieler JT, Holzer M. Tau and tauopathies. Brain Res Bull 2016; 126:238-292. [DOI: 10.1016/j.brainresbull.2016.08.018] [Citation(s) in RCA: 333] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/31/2016] [Accepted: 08/31/2016] [Indexed: 12/11/2022]
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Bukar Maina M, Al-Hilaly YK, Serpell LC. Nuclear Tau and Its Potential Role in Alzheimer's Disease. Biomolecules 2016; 6:9. [PMID: 26751496 PMCID: PMC4808803 DOI: 10.3390/biom6010009] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 12/16/2015] [Accepted: 12/23/2015] [Indexed: 12/14/2022] Open
Abstract
Tau protein, found in both neuronal and non-neuronal cells, forms aggregates in neurons that constitutes one of the hallmarks of Alzheimer’s disease (AD). For nearly four decades, research efforts have focused more on tau’s role in physiology and pathology in the context of the microtubules, even though, for over three decades, tau has been localised in the nucleus and the nucleolus. Its nuclear and nucleolar localisation had stimulated many questions regarding its role in these compartments. Data from cell culture, mouse brain, and the human brain suggests that nuclear tau could be essential for genome defense against cellular distress. However, its nature of translocation to the nucleus, its nuclear conformation and interaction with the DNA and other nuclear proteins highly suggest it could play multiple roles in the nucleus. To find efficient tau-based therapies, there is a need to understand more about the functional relevance of the varied cellular distribution of tau, identify whether specific tau transcripts or isoforms could predict tau’s localisation and function and how they are altered in diseases like AD. Here, we explore the cellular distribution of tau, its nuclear localisation and function and its possible involvement in neurodegeneration.
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Affiliation(s)
- Mahmoud Bukar Maina
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, East Sussex, UK.
- Department of Human Anatomy, College of Medical Science, Gombe State University, Gombe 760, Nigeria.
| | - Youssra K Al-Hilaly
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, East Sussex, UK.
- Chemistry Department, College of Sciences, Al-Mustansiriyah University, Baghdad, Iraq.
| | - Louise C Serpell
- School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, East Sussex, UK.
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21
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Zha GB, Shen M, Gu XS, Yi S. Changes in microtubule-associated protein tau during peripheral nerve injury and regeneration. Neural Regen Res 2016; 11:1506-1511. [PMID: 27857758 PMCID: PMC5090857 DOI: 10.4103/1673-5374.191227] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Tau, a primary component of microtubule-associated protein, promotes microtubule assembly and/or disassembly and maintains the stability of the microtubule structure. Although the importance of tau in neurodegenerative diseases has been well demonstrated, whether tau is involved in peripheral nerve regeneration remains unknown. In the current study, we obtained sciatic nerve tissue from adult rats 0, 1, 4, 7, and 14 days after sciatic nerve crush and examined tau mRNA and protein expression levels and the location of tau in the sciatic nerve following peripheral nerve injury. The results from our quantitative reverse transcription polymerase chain reaction analysis showed that compared with the uninjured control sciatic nerve, mRNA expression levels for both tau and tau tubulin kinase 1, a serine/threonine kinase that regulates tau phosphorylation, were decreased following peripheral nerve injury. Our western blot assay results suggested that the protein expression levels of tau and phosphorylated tau initially decreased 1 day post nerve injury but then gradually increased. The results of our immunohistochemical labeling showed that the location of tau protein was not altered by nerve injury. Thus, these results showed that the expression of tau was changed following sciatic nerve crush, suggesting that tau may be involved in peripheral nerve repair and regeneration.
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Affiliation(s)
- Guang-Bin Zha
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Mi Shen
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Xiao-Song Gu
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Sheng Yi
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
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22
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Kahn OI, Ha N, Baird MA, Davidson MW, Baas PW. TPX2 regulates neuronal morphology through kinesin-5 interaction. Cytoskeleton (Hoboken) 2015; 72:340-8. [PMID: 26257190 DOI: 10.1002/cm.21234] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Revised: 08/05/2015] [Accepted: 08/06/2015] [Indexed: 01/19/2023]
Abstract
TPX2 (targeting protein for Xklp2) is a multifunctional mitotic spindle assembly factor that in mammalian cells localizes and regulates mitotic motor protein kinesin-5 (also called Eg5 or kif11). We previously showed that upon depletion or inhibition of kinesin-5 in cultured neurons, microtubule movements increase, resulting in faster growing axons and thinner dendrites. Here, we show that depletion of TPX2 from cultured neurons speeds their rate of process outgrowth, similarly to kinesin-5 inhibition. The phenotype is rescued by TPX2 re-expression, but not if TPX2's kinesin-5-interacting domain is deleted. These results, together with studies showing a spike in TPX2 expression during dendritic differentiation, suggest that the levels and distribution of TPX2 are likely to be determinants of when and where kinesin-5 acts in neurons.
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Affiliation(s)
- Olga I Kahn
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Ngoc Ha
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Michelle A Baird
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, Florida
| | - Michael W Davidson
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, Florida
| | - Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
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23
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Kahn OI, Sharma V, González-Billault C, Baas PW. Effects of kinesin-5 inhibition on dendritic architecture and microtubule organization. Mol Biol Cell 2014; 26:66-77. [PMID: 25355946 PMCID: PMC4279230 DOI: 10.1091/mbc.e14-08-1313] [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] [Indexed: 01/13/2023] Open
Abstract
Inhibition of kinesin-5, a molecular motor protein best known for its essential role in mitosis, has notable effects on the morphology and microtubule organization of dendrites of terminally postmitotic neurons. Kinesin-5 acts as a brake that can limit the capacity of other motor proteins to influence microtubule organization and distribution. Kinesin-5 is a slow homotetrameric motor protein best known for its essential role in the mitotic spindle, where it limits the rate at which faster motors can move microtubules. In neurons, experimental suppression of kinesin-5 causes the axon to grow faster by increasing the mobility of microtubules in the axonal shaft and the invasion of microtubules into the growth cone. Does kinesin-5 act differently in dendrites, given that they have a population of minus end–distal microtubules not present in axons? Using rodent primary neurons in culture, we found that inhibition of kinesin-5 during various windows of time produces changes in dendritic morphology and microtubule organization. Specifically, dendrites became shorter and thinner and contained a greater proportion of minus end–distal microtubules, suggesting that kinesin-5 acting normally restrains the number of minus end–distal microtubules that are transported into dendrites. Additional data indicate that, in neurons, CDK5 is the kinase responsible for phosphorylating kinesin-5 at Thr-926, which is important for kinesin-5 to associate with microtubules. We also found that kinesin-5 associates preferentially with microtubules rich in tyrosinated tubulin. This is consistent with an observed accumulation of kinesin-5 on dendritic microtubules, as they are known to be less detyrosinated than axonal microtubules.
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Affiliation(s)
- Olga I Kahn
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129
| | - Vandana Sharma
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129
| | - Christian González-Billault
- Department of Biology and Institute for Cell Dynamics and Biotechnology (ICDB), Faculty of Sciences, Universidad de Chile, 7800024 Nunoa, Santiago, Chile
| | - Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129
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24
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Cragg CL, Kalisch BE. Nerve Growth Factor Enhances Tau Isoform Expression and Transcription in IMR32 Cells. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/nm.2014.52015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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26
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Yang WI, Oh JT. Calretinin and microtubule-associated protein-2 (MAP-2) immunohistochemistry in the diagnosis of Hirschsprung's disease. J Pediatr Surg 2013; 48:2112-7. [PMID: 24094966 DOI: 10.1016/j.jpedsurg.2013.02.067] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 01/15/2023]
Abstract
BACKGROUND/PURPOSE Identifying ganglion cells by rectal suction biopsy is a basic diagnostic tool for the diagnosis of Hirschsprung's disease (HD). However, the difficult interpretation of conventionally processed slides often necessitates ancillary staining methods. The aim of this study was to evaluate the usefulness of calretinin and microtubule-associated protein-2 (MAP-2) immunohistochemistry in the diagnosis of HD. METHODS We analyzed 52 rectal suction biopsy specimens (37 from 15 HD patients and 15 from 7 non-HD patients) for ganglion cells with calretinin and MAP-2 immunohistochemistry. We also analyzed full-thickness, frozen biopsy samples obtained from 15 HD patients who underwent surgery utilizing calretinin and MAP-2 immunohistochemistry. RESULTS Both calretinin and MAP-2 positively stained ganglion cells in the submucosal plexus of the ganglionic bowel but not aganglionic bowel. Calretinin usually stained ganglion cell cytoplasm and nuclei more intensely than MAP-2, which only stained cytoplasm. No nerve fiber staining in the submucosal layer was observed for either antibody. In 21.1% (11/52) of samples, calretinin and MAP-2 staining found ganglion cells which were reported not to have ganglion cells in the original surgical pathology reports. Immunohistochemical staining for calretinin using paraffin-embedded tissue sections after cryostat sections clearly demonstrated decreased staining intensity compared to MAP-2. CONCLUSION Calretinin and MAP-2 are useful diagnostic markers for diagnosing HD in rectal suction biopsies. These complementary methods could ameliorate the diagnostic difficulties associated with HD.
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Affiliation(s)
- Woo Ick Yang
- Department of Pathology, Yonsei University College of Medicine, Seoul, Korea
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27
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Abstract
Microtubules are nearly uniformly oriented in the axons of vertebrate neurons but are non-uniformly oriented in their dendrites. Studies to date suggest a scenario for establishing these microtubule patterns whereby microtubules are transported into the axon and nascent dendrites with plus-ends-leading, and then additional microtubules of the opposite orientation are transported into the developing dendrites. Here, we used contemporary tools to confirm that depletion of kinesin-6 (also called CHO1/MKLP1 or kif23) from rat sympathetic neurons causes a reduction in the appearance of minus-end-distal microtubules in developing dendrites, which in turn causes them to assume an axon-like morphology. Interestingly, we observed a similar phenomenon when we depleted kinesin-12 (also called kif15 or HKLP2). Both motors are best known for their participation in mitosis in other cell types, and both are enriched in the cell body and dendrites of neurons. Unlike kinesin-12, which is present throughout the neuron, kinesin-6 is barely detectable in the axon. Accordingly, depletion of kinesin-6, unlike depletion of kinesin-12, has no effect on axonal branching or navigation. Interestingly, depletion of either motor results in faster growing axons with greater numbers of mobile microtubules. Based on these observations, we posit a model whereby these two motors generate forces that attenuate the transport of microtubules with plus-ends-leading from the cell body into the axon. Some of these microtubules are not only prevented from moving into the axon but are driven with minus-ends-leading into developing dendrites. In this manner, these so-called "mitotic" motors coregulate the microtubule patterns of axons and dendrites.
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Craddock TJA, Tuszynski JA, Chopra D, Casey N, Goldstein LE, Hameroff SR, Tanzi RE. The zinc dyshomeostasis hypothesis of Alzheimer's disease. PLoS One 2012; 7:e33552. [PMID: 22457776 PMCID: PMC3311647 DOI: 10.1371/journal.pone.0033552] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 02/13/2012] [Indexed: 11/20/2022] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia in the elderly. Hallmark AD neuropathology includes extracellular amyloid plaques composed largely of the amyloid-β protein (Aβ), intracellular neurofibrillary tangles (NFTs) composed of hyper-phosphorylated microtubule-associated protein tau (MAP-tau), and microtubule destabilization. Early-onset autosomal dominant AD genes are associated with excessive Aβ accumulation, however cognitive impairment best correlates with NFTs and disrupted microtubules. The mechanisms linking Aβ and NFT pathologies in AD are unknown. Here, we propose that sequestration of zinc by Aβ-amyloid deposits (Aβ oligomers and plaques) not only drives Aβ aggregation, but also disrupts zinc homeostasis in zinc-enriched brain regions important for memory and vulnerable to AD pathology, resulting in intra-neuronal zinc levels, which are either too low, or excessively high. To evaluate this hypothesis, we 1) used molecular modeling of zinc binding to the microtubule component protein tubulin, identifying specific, high-affinity zinc binding sites that influence side-to-side tubulin interaction, the sensitive link in microtubule polymerization and stability. We also 2) performed kinetic modeling showing zinc distribution in extra-neuronal Aβ deposits can reduce intra-neuronal zinc binding to microtubules, destabilizing microtubules. Finally, we 3) used metallomic imaging mass spectrometry (MIMS) to show anatomically-localized and age-dependent zinc dyshomeostasis in specific brain regions of Tg2576 transgenic, mice, a model for AD. We found excess zinc in brain regions associated with memory processing and NFT pathology. Overall, we present a theoretical framework and support for a new theory of AD linking extra-neuronal Aβ amyloid to intra-neuronal NFTs and cognitive dysfunction. The connection, we propose, is based on β-amyloid-induced alterations in zinc ion concentration inside neurons affecting stability of polymerized microtubules, their binding to MAP-tau, and molecular dynamics involved in cognition. Further, our theory supports novel AD therapeutic strategies targeting intra-neuronal zinc homeostasis and microtubule dynamics to prevent neurodegeneration and cognitive decline.
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SPM1 stabilizes subpellicular microtubules in Toxoplasma gondii. EUKARYOTIC CELL 2011; 11:206-16. [PMID: 22021240 DOI: 10.1128/ec.05161-11] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have identified two novel proteins that colocalize with the subpellicular microtubules in the protozoan parasite Toxoplasma gondii and named these proteins SPM1 and SPM2. These proteins have basic isoelectric points and both have homologs in other apicomplexan parasites. SPM1 contains six tandem copies of a 32-amino-acid repeat, whereas SPM2 lacks defined protein signatures. Alignment of Toxoplasma SPM2 with apparent Plasmodium SPM2 homologs indicates that the greatest degree of conservation lies in the carboxy-terminal half of the protein. Analysis of Plasmodium homologs of SPM1 indicates that while the central 32-amino-acid repeats have expanded to different degrees (7, 8, 9, 12, or 13 repeats), the amino- and carboxy-terminal regions remain conserved. In contrast, although the Cryptosporidium SPM1 homolog has a conserved carboxy tail, the five repeats are considerably diverged, and it has a smaller amino-terminal domain. SPM1 is localized along the full length of the subpellicular microtubules but does not associate with the conoid or spindle microtubules. SPM2 has a restricted localization along the middle region of the subpellicular microtubules. Domain deletion analysis indicates that four or more copies of the SPM1 repeat are required for localization to microtubules, and the amino-terminal 63 residues of SPM2 are required for localization to the subpellicular microtubules. Gene deletion studies indicate that neither SPM1 nor SPM2 is essential for tachyzoite viability. However, loss of SPM1 decreases overall parasite fitness and eliminates the stability of subpellicular microtubules to detergent extraction.
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Fujiwara Y, Kasashima K, Saito K, Fukuda M, Fukao A, Sasano Y, Inoue K, Fujiwara T, Sakamoto H. Microtubule association of a neuronal RNA-binding protein HuD through its binding to the light chain of MAP1B. Biochimie 2011; 93:817-22. [PMID: 21288476 DOI: 10.1016/j.biochi.2011.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 01/20/2011] [Indexed: 11/30/2022]
Abstract
RNA-binding proteins (RBPs) play a vital role in the post-transcriptional regulation of gene expression during neuronal differentiation and synaptic plasticity. One such RBP family, the neuronal Hu protein family, serves as an early marker of neuronal differentiation and targets several mRNAs containing adenine/uridine-rich elements. Recently, we reported that one of the neuronal Hu proteins, HuD stimulates cap-dependent translation through interactions with eIF4A and poly (A) tail. Nevertheless, little is known with respect to how neuronal Hu proteins contribute to the local translation of target mRNAs in neuronal differentiation. Here, we found that neuronal Hu proteins, but not the ubiquitously expressed HuR protein, directly interact with the light chain of microtubule-associated proteins MAP1B (LC1). We also show that HuD simultaneously binds both RNA and LC1 in vitro and that it tightly associates with microtubules in cells in an LC1-dependent manner, raising the possibility that HuD recruits target mRNAs to microtubules. These results uncover the neuronal binding partners for neuron-specific Hu proteins and suggest the involvement of Hu proteins in microtubule-mediated regulation of mRNA expression within neuronal processes.
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Affiliation(s)
- Yuki Fujiwara
- Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan
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Lamoureux PL, O'Toole MR, Heidemann SR, Miller KE. Slowing of axonal regeneration is correlated with increased axonal viscosity during aging. BMC Neurosci 2010; 11:140. [PMID: 20973997 PMCID: PMC2975647 DOI: 10.1186/1471-2202-11-140] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 10/25/2010] [Indexed: 12/13/2022] Open
Abstract
Background As we age, the speed of axonal regeneration declines. At the biophysical level, why this occurs is not well understood. Results To investigate we first measured the rate of axonal elongation of sensory neurons cultured from neonatal and adult rats. We found that neonatal axons grew 40% faster than adult axons (11.5 µm/hour vs. 8.2 µm/hour). To determine how the mechanical properties of axons change during maturation, we used force calibrated towing needles to measure the viscosity (stiffness) and strength of substrate adhesion of neonatal and adult sensory axons. We found no significant difference in the strength of adhesions, but did find that adult axons were 3 times intrinsically stiffer than neonatal axons. Conclusions Taken together, our results suggest decreasing axonal stiffness may be part of an effective strategy to accelerate the regeneration of axons in the adult peripheral nervous system.
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Affiliation(s)
- Phillip L Lamoureux
- Department of Zoology, Michigan State University, East Lansing, MI 48824-1115, USA
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32
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Seira O, Gavín R, Gil V, Llorens F, Rangel A, Soriano E, del Río JA. Neurites regrowth of cortical neurons by GSK3beta inhibition independently of Nogo receptor 1. J Neurochem 2010; 113:1644-58. [PMID: 20374426 DOI: 10.1111/j.1471-4159.2010.06726.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Lesioned axons do not regenerate in the adult mammalian CNS, owing to the over-expression of inhibitory molecules such as myelin-derived proteins or chondroitin sulphate proteoglycans. In order to overcome axon inhibition, strategies based on extrinsic and intrinsic treatments have been developed. For myelin-associated inhibition, blockage with NEP1-40, receptor bodies or IN-1 antibodies has been used. In addition, endogenous blockage of cell signalling mechanisms induced by myelin-associated proteins is a potential tool for overcoming axon inhibitory signals. We examined the participation of glycogen synthase kinase 3beta (GSK3beta) and extracellular-related kinase (ERK) 1/2 in axon regeneration failure in lesioned cortical neurons. We also investigated whether pharmacological blockage of GSK3beta and ERK1/2 activities facilitates regeneration after myelin-directed inhibition in two models: (i) cerebellar granule cells and (ii) lesioned entorhino-hippocampal pathway in slice cultures, and whether the regenerative effects are mediated by Nogo Receptor 1 (NgR1). We demonstrate that, in contrast to ERK1/2 inhibition, the pharmacological treatment of GSK3beta inhibition strongly facilitated regrowth of cerebellar granule neurons over myelin independently of NgR1. Finally, these regenerative effects were corroborated in the lesioned entorhino-hippocampal pathway in NgR1-/- mutant mice. These results provide new findings for the development of new assays and strategies to enhance axon regeneration in injured cortical connections.
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Affiliation(s)
- Oscar Seira
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia, Barcelona, Spain
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33
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Dynamic changes of neuroskeletal proteins in DRGs underlie impaired axonal maturation and progressive axonal degeneration in type 1 diabetes. EXPERIMENTAL DIABETES RESEARCH 2009; 2009:793281. [PMID: 19834568 PMCID: PMC2761046 DOI: 10.1155/2009/793281] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 07/07/2009] [Indexed: 11/18/2022]
Abstract
We investigated mechanisms underlying progressive axonal dysfunction and structural deficits in type 1 BB/Wor-rats from 1 week to 10 month diabetes duration. Motor and sensory conduction velocities were decreased after 4 and 6 weeks of diabetes and declined further over the remaining 9 months. Myelinated sural nerve fibers showed progressive deficits in fiber numbers and sizes. Structural deficits in unmyelinated axonal size were evident at 2 month and deficits in number were present at 4 mo. These changes were preceded by decreased availability of insulin, C-peptide and IGF-1 and decreased expression of neurofilaments and β-III-tubulin. Upregulation of phosphorylating stress kinases like Cdk5, p-GSK-3β, and p42/44 resulted in increased phosphorylation of neurofilaments. Increasing activity of p-GSK-3β correlated with increasing phosphorylation of NFH, whereas decreasing Cdk5 correlated with diminishing phosphorylation of NFM. The data suggest that impaired neurotrophic support results in sequentially impaired synthesis and postranslational modifications of neuroskeletal proteins, resulting in progressive deficits in axonal function, maturation and size.
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Utility of Microtubule Associated Protein-2 (MAP-2) Immunohistochemistry for Identification of Ganglion Cells in Paraffin-Embedded Rectal Suction Biopsies. Am J Surg Pathol 2009; 33:1025-30. [DOI: 10.1097/pas.0b013e31819b23f2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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35
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Steibel JP, Wysocki M, Lunney JK, Ramos AM, Hu ZL, Rothschild MF, Ernst CW. Assessment of the swine protein-annotated oligonucleotide microarray. Anim Genet 2009; 40:883-93. [PMID: 19515086 DOI: 10.1111/j.1365-2052.2009.01928.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The specificity and utility of the swine protein-annotated oligonucleotide microarray, or Pigoligoarray (http://www.pigoligoarray.org), has been evaluated by profiling the expression of transcripts from four porcine tissues. Tools for comparative analyses of expression on the Pigoligoarray were developed including HGNC identities and comparative mapping alignments with human orthologs. Hybridization results based on the Pigoligoarray's sets of control, perfect match (PM) and deliberate mismatch (MM) probes provide an important means of assessing non-specific hybridization. Simple descriptive diagnostic analyses of PM/MM probe sets are introduced in this paper as useful tools for detecting non-specific hybridization. Samples of RNA from liver, brain stem, longissimus dorsi muscle and uterine endothelium from four pigs were prepared and hybridized to the arrays. Of the total 20,400 oligonucleotides on the Pigoligoarray, 12,429 transcripts were putatively differentially expressed (DE). Analyses for tissue-specific expression [over-expressed in one tissue with respect to all the remaining three tissues (q < 0.01)] identified 958 DE transcripts in liver, 726 in muscle, 286 in uterine endothelium and 1027 in brain stem. These hybridization results were confirmed by quantitative PCR (QPCR) expression patterns for a subset of genes after affirming that cDNA and amplified antisense RNA (aRNA) exhibited similar QPCR results. Comparison to human ortholog expression confirmed the value of this array for experiments of both agricultural importance and for tests using pigs as a biomedical model for human disease.
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Affiliation(s)
- J P Steibel
- Department of Animal Science, Michigan State University, East Lansing, MI 48824, USA.
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36
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Smeal RM, Tresco PA. The influence of substrate curvature on neurite outgrowth is cell type dependent. Exp Neurol 2008; 213:281-92. [DOI: 10.1016/j.expneurol.2008.05.026] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 05/29/2008] [Accepted: 05/30/2008] [Indexed: 01/04/2023]
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37
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Liu F, Gong CX. Tau exon 10 alternative splicing and tauopathies. Mol Neurodegener 2008; 3:8. [PMID: 18616804 PMCID: PMC2483273 DOI: 10.1186/1750-1326-3-8] [Citation(s) in RCA: 212] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 07/10/2008] [Indexed: 01/27/2023] Open
Abstract
Abnormalities of microtubule-associated protein tau play a central role in neurofibrillary degeneration in several neurodegenerative disorders that collectively called tauopathies. Six isoforms of tau are expressed in adult human brain, which result from alternative splicing of pre-mRNA generated from a single tau gene. Alternative splicing of tau exon 10 results in tau isoforms containing either three or four microtubule-binding repeats (3R-tau and 4R-tau, respectively). Approximately equal levels of 3R-tau and 4R-tau are expressed in normal adult human brain, but the 3R-tau/4R-tau ratio is altered in the brains in several tauopathies. Discovery of silence mutations and intronic mutations of tau gene in some individuals with frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17), which only disrupt tau exon 10 splicing but do not alter tau's primary sequence, demonstrates that dysregulation of tau exon 10 alternative splicing and consequently of 3R-tau/4R-tau balance is sufficient to cause neurodegeneration and dementia. Here, we review the gene structure, transcripts and protein isoforms of tau, followed by the regulation of exon 10 splicing that determines the expression of 3R-tau or 4R-tau. Finally, dysregulation of exon 10 splicing of tau in several tauopathies is discussed. Understanding the molecular mechanisms by which tau exon 10 splicing is regulated and how it is disrupted in tauopathies will provide new insight into the mechanisms of these tauopathies and help identify new therapeutic targets to treat these disorders.
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Affiliation(s)
- Fei Liu
- Department of Neurochemistry, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York 10314, USA.
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Chau V, Clément JF, Robitaille Y, D'Anjou G, Vanasse M. Congenital axonal neuropathy and encephalopathy. Pediatr Neurol 2008; 38:261-6. [PMID: 18358405 DOI: 10.1016/j.pediatrneurol.2007.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 09/25/2007] [Accepted: 11/20/2007] [Indexed: 10/22/2022]
Abstract
Congenital axonal neuropathy associated with encephalopathy appears to be very rare. Only a few cases have been reported in the literature. In the last 25 years, we have seen seven patients affected by congenital axonal neuropathy with encephalopathy. Biopsies of their sural nerves revealed axonal atrophy and loss of large-diameter nerve fibers. All of these patients presented at birth or soon thereafter with hypotonia associated with distal weakness and diffuse areflexia. Central nervous system manifestations included microcephaly, seizures, and developmental delay. Outcomes were poor. Four children died before age 3 years from respiratory insufficiency or aspiration pneumonia. The three surviving patients manifested severe developmental delay. In our most recent patient, Western-blot analysis of snap-frozen specimens of the temporal and cerebellar cortex demonstrated an absence or marked decrease of microtubule-associated protein types 1A and 2, compared with age-matched control subjects. Calloso-splenial hypogenesis and neurofilament swellings were also documented in the deep white matter and adjacent cortex. The absence or hypo-expression of central nervous system microtubule-associated proteins has never been reported in congenital neuropathies, and may represent a new clinicopathologic entity.
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Affiliation(s)
- Vann Chau
- Division of Neurology, Department of Pediatrics, Centre Hospitalier Universitaire Sainte-Justine, University of Montreal, Montreal, Quebec, Canada
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Sima AAF, Zhang W, Li ZG, Kamiya H. The effects of C-peptide on type 1 diabetic polyneuropathies and encephalopathy in the BB/Wor-rat. EXPERIMENTAL DIABETES RESEARCH 2008; 2008:230458. [PMID: 18437223 PMCID: PMC2323445 DOI: 10.1155/2008/230458] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Accepted: 01/07/2008] [Indexed: 12/29/2022]
Abstract
Diabetic polyneuropathy (DPN) occurs more frequently in type 1 diabetes resulting in a more severe DPN. The differences in DPN between the two types of diabetes are due to differences in the availability of insulin and C-peptide. Insulin and C-peptide provide gene regulatory effects on neurotrophic factors with effects on axonal cytoskeletal proteins and nerve fiber integrity. A significant abnormality in type 1 DPN is nodal degeneration. In the type 1 BB/Wor-rat, C-peptide replacement corrects metabolic abnormalities ameliorating the acute nerve conduction defect. It corrects abnormalities of neurotrophic factors and the expression of neuroskeletal proteins with improvements of axonal size and function. C-peptide corrects the expression of nodal adhesive molecules with prevention and repair of the functionally significant nodal degeneration. Cognitive dysfunction is a recognized complication of type 1 diabetes, and is associated with impaired neurotrophic support and apoptotic neuronal loss. C-peptide prevents hippocampal apoptosis and cognitive deficits. It is therefore clear that substitution of C-peptide in type 1 diabetes has a multitude of effects on DPN and cognitive dysfunction. Here the effects of C-peptide replenishment will be extensively described as they pertain to DPN and diabetic encephalopathy, underpinning its beneficial effects on neurological complications in type 1 diabetes.
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Affiliation(s)
- Anders A F Sima
- Department of Pathology, Wayne State University, Detroit, MI 48201, USA.
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40
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Riederer BM. Microtubule-associated protein 1B, a growth-associated and phosphorylated scaffold protein. Brain Res Bull 2006; 71:541-58. [PMID: 17292797 DOI: 10.1016/j.brainresbull.2006.11.012] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Accepted: 11/28/2006] [Indexed: 11/25/2022]
Abstract
Microtubule-associated protein 1B, MAP1B, is one of the major growth associated and cytoskeletal proteins in neuronal and glial cells. It is present as a full length protein or may be fragmented into a heavy chain and a light chain. It is essential to stabilize microtubules during the elongation of dendrites and neurites and is involved in the dynamics of morphological structures such as microtubules, microfilaments and growth cones. MAP1B function is modulated by phosphorylation and influences microtubule stability, microfilaments and growth cone motility. Considering its large size, several interactions with a variety of other proteins have been reported and there is increasing evidence that MAP1B plays a crucial role in the stability of the cytoskeleton and may have other cellular functions. Here we review molecular and functional aspects of this protein, evoke its role as a scaffold protein and have a look at several pathologies where the protein may be involved.
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Affiliation(s)
- Beat M Riederer
- Département de Biologie Cellulaire et de Morphologi), Université de Lausanne, 9 rue du Bugnon, CH-1005 Lausanne, Switzerland.
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41
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Wang J, Tse SW, Andreadis A. Tau exon 6 is regulated by an intricate interplay of trans factors and cis elements, including multiple branch points. J Neurochem 2006; 100:437-45. [PMID: 17144905 DOI: 10.1111/j.1471-4159.2006.04252.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Tau is a microtubule-associated protein whose transcript undergoes complex regulated splicing in the mammalian nervous system. Exon 6 of the gene is an alternatively spliced cassette whose expression profile differs from that of the other tau regulated exons, implying the involvement of distinct regulatory factors. Previous work had established the existence and use of two additional 3' splice sites within exon 6 and the influence of splicing factors polypyrimidine binding protein (PTB) and U2AF on its splicing. The present work shows that exon 6 isoforms exist in distinct ratios in different compartments of the nervous system and that splicing of exon 6 is governed by multiple branch points, exonic cis elements and additional trans factors. Recent results show that tau exon 6 is specifically suppressed in the brains of people who suffer from myotonic dystrophy type 1. The understanding of how tau exon 6 splicing is regulated may give us insights into the disease.
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Affiliation(s)
- Junning Wang
- Shriver Center at University of Massachusetts Medical School, Waltham, Massachusetts 02452, USA
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42
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Nakazawa T, Morii H, Tamai M, Mori N. Selective upregulation of RB3/stathmin4 by ciliary neurotrophic factor following optic nerve axotomy. Brain Res 2005; 1061:97-106. [PMID: 16256088 DOI: 10.1016/j.brainres.2005.08.055] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 08/22/2005] [Accepted: 08/28/2005] [Indexed: 11/16/2022]
Abstract
In this study, we examined the cellular responses of stathmin-related proteins in the rat retina following optic nerve (ON) axotomy. To examine the distribution of stathmin-related gene products, we performed semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), in situ hybridization (ISH) and immunohistochemical analyses. Retrograde labeling using a fluorescein tracer, fluorogold (FG), was used for the identification of retinal ganglion cells (RGCs). RT-PCR and ISH analyses indicated that the expression of RB3 was specifically increased in the ganglion cell layer (GCL) comparing to other members of stathmin-related gene family examined 3 days following the ON axotomy. When brain-derived neurotrophic factor was administrated intravitreously, the induction of RB3 mRNA sustained up to 7 days after axotomy, although the peak induction level was unchanged. In contrast, ciliary neurotrophic factor (CNTF) administration increased the peak level of RB3 mRNA induction significantly at 3 days after axotomy. Immunohistochemistry in combination with the retrograde labeling of axotomized cells by FG revealed that RB3 was increased following axotomy in FG-labeled RGCs. These data suggest that RB3 is the unique response protein in the stathmin-related proteins following ON axotomy and the induced RB3 may play a critical role in the CNTF-induced response on the axotomized RGCs, e.g. axonal regeneration and/or neuroprotection.
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Affiliation(s)
- Toru Nakazawa
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
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Luo MH, Leski ML, Andreadis A. Tau isoforms which contain the domain encoded by exon 6 and their role in neurite elongation. J Cell Biochem 2005; 91:880-95. [PMID: 15034924 DOI: 10.1002/jcb.20029] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The regulation of tau protein expression during different stages of cellular differentiation and development as well as its functional role in morphogenesis, neurofibrillary tangle formation, and neurodegeneration have been topics of extensive study but have not been completely clarified yet. Tau undergoes complex regulated splicing in the mammalian nervous system. Our previous study with tau exon 6 demonstrated that it shows a splicing regulation profile which is distinct from that of the other tau exons as well as a unique expression pattern which is spatially and temporally regulated. In this study, we investigated the expression, localization, and effects of tau isoforms which contain exon 6 in neuroblastoma cells which stably overexpress them. We found that expression of one particular combination of tau exons (the longest adult isoform plus the domain of exon 6) significantly inhibits neurite elongation.
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Affiliation(s)
- Min-Hua Luo
- Neurobiology of Developmental Disorders, Shriver Center for Mental Retardation, Waltham, Massachusetts 02452, USA
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Andreadis A. Tau gene alternative splicing: expression patterns, regulation and modulation of function in normal brain and neurodegenerative diseases. Biochim Biophys Acta Mol Basis Dis 2005; 1739:91-103. [PMID: 15615629 DOI: 10.1016/j.bbadis.2004.08.010] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2004] [Accepted: 08/27/2004] [Indexed: 12/12/2022]
Abstract
Organization of cytoskeletal elements is critical for cellular migration and maintenance of morphology. Tau protein, which binds to and organizes microtubules, is instrumental in forming and maintaining the neuronal axon. Disturbances in tau expression result in disruption of the neuronal cytoskeleton and formation of pathological tau structures (neurofibrillary tangles, NFTs) found in brains of dementia sufferers. Null tau mice, although viable, exhibit developmental and cognitive defects and transgenic mice which overexpress tau develop severe neuropathies. The neuron-specific tau transcript produces multiple isoforms by intricately regulated alternative splicing. These isoforms modulate tau function in normal brain. Moreover, aberrations in tau splicing regulation directly cause several neurodegenerative diseases. Thus, tau splicing regulation is vital to neuronal health and correct brain function. This review briefly presents our cumulative knowledge of tau splicing-cis elements and trans factors which influence it at the RNA level, its effect on the structure and roles of the tau protein and its repercussions on neuronal morphology and neurodegeneration.
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Affiliation(s)
- Athena Andreadis
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 06155, USA.
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Di Giovanni S, Faden AI, Yakovlev A, Duke-Cohan JS, Finn T, Thouin M, Knoblach S, De Biase A, Bregman BS, Hoffman EP. Neuronal plasticity after spinal cord injury: identification of a gene cluster driving neurite outgrowth. FASEB J 2004; 19:153-4. [PMID: 15522907 DOI: 10.1096/fj.04-2694fje] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Functional recovery after spinal cord injury (SCI) may result in part from axon outgrowth and related plasticity through coordinated changes at the molecular level. We employed microarray analysis to identify a subset of genes the expression patterns of which were temporally coregulated and correlated to functional recovery after SCI. Steady-state mRNA levels of this synchronously regulated gene cluster were depressed in both ventral and dorsal horn neurons within 24 h after injury, followed by strong re-induction during the following 2 wk, which paralleled functional recovery. The identified cluster includes neuritin, attractin, microtubule-associated protein 1a, and myelin oligodendrocyte protein genes. Transcriptional and protein regulation of this novel gene cluster was also evaluated in spinal cord tissue and in single neurons and was shown to play a role in axonal plasticity. Finally, in vitro transfection experiments in primary dorsal root ganglion cells showed that cluster members act synergistically to drive neurite outgrowth.
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Affiliation(s)
- Simone Di Giovanni
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, USA
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Broderick J, Wang J, Andreadis A. Heterogeneous nuclear ribonucleoprotein E2 binds to tau exon 10 and moderately activates its splicing. Gene 2004; 331:107-14. [PMID: 15094196 DOI: 10.1016/j.gene.2004.02.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2003] [Revised: 01/16/2004] [Accepted: 02/04/2004] [Indexed: 10/26/2022]
Abstract
Tau is a microtubule-associated protein whose transcript undergoes complex-regulated splicing in the mammalian nervous system. Exon 10 of the gene is an alternatively spliced cassette, which is adult-specific and codes for a microtubule-binding domain. Mutations that affect splicing of exon 10 have been shown to cause frontotemporal dementia with parkinsonism (FTDP). Using tau exon 10 as a bait in a yeast three-hybrid screen, we discovered that it interacts with hnRNPE2. Cotransfection assays show that hnRNPE2 isoforms moderately activate the splicing of exon 10.
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47
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Wang J, Gao QS, Wang Y, Lafyatis R, Stamm S, Andreadis A. Tau exon 10, whose missplicing causes frontotemporal dementia, is regulated by an intricate interplay of cis elements and trans factors. J Neurochem 2004; 88:1078-90. [PMID: 15009664 DOI: 10.1046/j.1471-4159.2003.02232.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Tau is a microtubule-associated protein whose transcript undergoes complex regulated splicing in the mammalian nervous system. In humans, exon 10 of the gene is an alternatively spliced cassette which is adult-specific and which codes for a microtubule binding domain. Mutations that affect splicing of exon 10 have been shown to cause inherited frontotemporal dementia (FTDP). In this study, we reconstituted naturally occurring exon 10 FTDP mutants and classified their effects on its splicing. We also carried out a comprehensive survey of the influence of splicing regulators on exon 10 inclusion and tentatively identified the site of action for several of these factors. Lastly, we identified the domains of regulators SWAP and hnRNPG, which are required for regulation of exon 10 splicing.
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Affiliation(s)
- Junning Wang
- Shriver Center at UMMS, Waltham, Massachusetts 02452, USA
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48
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Li K, Arikan MC, Andreadis A. Modulation of the membrane-binding domain of tau protein: splicing regulation of exon 2. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2003; 116:94-105. [PMID: 12941465 DOI: 10.1016/s0169-328x(03)00259-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Tau is a microtubule-associated protein whose transcript undergoes complex regulated splicing in the mammalian nervous system. The N-terminal domain of the protein interacts with the axonal membrane, and is modulated by regulated inclusion of exons 2 and 3. These two tau exons are alternatively spliced cassettes, in which exon 3 never appears independently of exon 2. Previous work with tau minigene constructs indicated that exon 2 resembles a constitutive exon. In this study, we show that exon 2 is regulated by a combination of exonic and intronic enhancers and silencers. Furthermore, we demonstrate that known splicing regulators affect the ratio of exon 2 isoforms. Lastly, we tentatively pinpoint the site of action of several splicing factors which regulate tau exon 2.
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Affiliation(s)
- Karen Li
- Division of Neurobiology of Developmental Disorders, Shriver Center for Mental Retardation at UMMS, Waltham, MA 02452, USA
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Aguezzoul M, Andrieux A, Denarier E. Overlap of promoter and coding sequences in the mouse STOP gene (Mtap6). Genomics 2003; 81:623-7. [PMID: 12782132 DOI: 10.1016/s0888-7543(03)00053-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The microtubule-associated proteins STOP are essential for synaptic plasticity and integrated brain function. The STOP gene (Mtap6) is composed of 4 exons and presents different developmental and tissue specific alternative transcripts resulting in the neuronal isoforms E- and N-STOP, and in the fibroblastic F-STOP isoform. We now characterize the transcription initiation sites for neuronal and non neuronal STOP transcripts. Our results show that there is a single neuronal specific promoter for transcription of E- and N-STOP mRNAs. F-STOP mRNA transcription is regulated by a distinct promoter. A remarkable feature of this promoter is that it lies within coding sequences expressed in neuronal E- and N-STOP isoforms.
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Affiliation(s)
- Mustapha Aguezzoul
- Laboratoire du Cytosquelette, INSERM U366, Départment Réponse et Dynamique Cellulaires, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble, Cedex 9, France
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Nakayama A, Murakami H, Maeyama N, Yamashiro N, Sakakibara A, Mori N, Takahashi M. Role for RFX transcription factors in non-neuronal cell-specific inactivation of the microtubule-associated protein MAP1A promoter. J Biol Chem 2003; 278:233-40. [PMID: 12411430 DOI: 10.1074/jbc.m209574200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microtubule-associated protein MAP1A is expressed abundantly in mature neurons and is necessary for maintenance of neuronal morphology and localization of some molecules in association with the microtubule-based cytoskeleton. Previous studies indicated that its complementary expression together with MAP1B during nervous system development is regulated at the transcriptional level and that the mouse Map1A gene is transcribed under the control of 5' and intronic promoters. In this study, we investigated the regulatory mechanisms that govern the neuronal cell-specific activation of the MAP1A 5' promoter. We found that two regulatory factor for X box (RFX) binding sites in exon1 of both the mouse and human genes are important for effective transcriptional repression observed only in non-neuronal cells by reporter assays. Among RFX transcription factor family members, RFX1 and 3 mainly interact with repressive elements in vitro. Cotransfection studies indicated that RFX1, which is expressed ubiquitously, down-regulated the MAP1A 5' promoter activity in non-neuronal cells. Unexpectedly, RFX3, which is abundantly expressed in neuronal cells, down-regulated the transactivity as well, when it was expressed in non-neuronal cells. Both RFX1 and 3 did not down-regulate the transactivity in neuronal cells. These results suggest that RFX1 and 3 are pivotal factors in down-regulation of the MAP1A 5' promoter in non-neuronal cells. The cell type-specific down-regulation, however, does not depend simply on which RFX interacts with the elements, but seems to depend on underlying profound mechanisms.
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Affiliation(s)
- Atsuo Nakayama
- Department of Pathology, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Aichi, Japan.
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