1
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Cohen LD, Ziv T, Ziv NE. Synapse integrity and function: Dependence on protein synthesis and identification of potential failure points. Front Mol Neurosci 2022; 15:1038614. [PMID: 36583084 PMCID: PMC9792512 DOI: 10.3389/fnmol.2022.1038614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 11/07/2022] [Indexed: 12/14/2022] Open
Abstract
Synaptic integrity and function depend on myriad proteins - labile molecules with finite lifetimes that need to be continually replaced with freshly synthesized copies. Here we describe experiments designed to expose synaptic (and neuronal) properties and functions that are particularly sensitive to disruptions in protein supply, identify proteins lost early upon such disruptions, and uncover potential, yet currently underappreciated failure points. We report here that acute suppressions of protein synthesis are followed within hours by reductions in spontaneous network activity levels, impaired oxidative phosphorylation and mitochondrial function, and, importantly, destabilization and loss of both excitatory and inhibitory postsynaptic specializations. Conversely, gross impairments in presynaptic vesicle recycling occur over longer time scales (days), as does overt cell death. Proteomic analysis identified groups of potentially essential 'early-lost' proteins including regulators of synapse stability, proteins related to bioenergetics, fatty acid and lipid metabolism, and, unexpectedly, numerous proteins involved in Alzheimer's disease pathology and amyloid beta processing. Collectively, these findings point to neuronal excitability, energy supply and synaptic stability as early-occurring failure points under conditions of compromised supply of newly synthesized protein copies.
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Affiliation(s)
- Laurie D. Cohen
- Technion Faculty of Medicine, Rappaport Institute and Network Biology Research Laboratories, Haifa, Israel
| | - Tamar Ziv
- Smoler Proteomics Center, Lokey Interdisciplinary Center for Life Sciences & Engineering, Technion, Haifa, Israel
| | - Noam E. Ziv
- Technion Faculty of Medicine, Rappaport Institute and Network Biology Research Laboratories, Haifa, Israel,*Correspondence: Noam E. Ziv,
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2
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Inuzuka H, Liu J, Wei W, Rezaeian AH. PROTACs technology for treatment of Alzheimer's disease: Advances and perspectives. ACTA MATERIA MEDICA 2022; 1:24-41. [PMID: 35237768 PMCID: PMC8887676 DOI: 10.15212/amm-2021-0001] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
Neurodegenerative diseases (NDs) are characteristic with progression of neuron degeneration, resulting in dysfunction of cognition and mobility. Many neurodegenerative diseases are because of proteinopathies that results from unusual protein accumulations and aggregations. The aggregation of misfolded proteins like β-amyloid, α-synuclein, tau, and polyglutamates are hallmarked in Alzheimer's disease (AD), which are undruggable targets, and usually do not respond to conventional small-molecule agents. Therefore, developing novel technology and strategy for reducing the levels of protein aggregates would be critical for treatment of AD. Recently, the emerging proteolysis targeting chimeras (PRPTACs) technology has been significantly considered for artificial and selective degradation of aberrant target proteins. These engineered bifunctional molecules engage target proteins to be degraded by either the cellular degradation machinery in the ubiquitin-proteasome system (UPS) or via the autophagy-lysosome degradation pathway. Although the application of PROTACs technology is preferable than oligonucleotide and antibodies for treatment of NDs, many limitations such as their pharmacokinetic properties, tissue distribution and cell permeabilities, still need to be corrected. Herein, we review the recent advances in PROTACs technology with their limitation for pharmaceutical targeting of aberrant proteins involved in Alzheimer's diseases. We also review therapeutic potential of dysregulated signaling such as PI3K/AKT/mTOR axis for the management of AD.
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Affiliation(s)
- Hiroyuki Inuzuka
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
| | - Jing Liu
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
- Corresponding author. Contact: ,
| | - Abdol-Hossein Rezaeian
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
- Corresponding author. Contact: ,
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3
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Galán B, Serdan T, Rodrigues L, Manoel R, Gorjão R, Masi L, Pithon-Curi T, Curi R, Hirabara S. Reviewing physical exercise in non-obese diabetic Goto-Kakizaki rats. Braz J Med Biol Res 2022; 55:e11795. [PMID: 35648976 PMCID: PMC9150428 DOI: 10.1590/1414-431x2022e11795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 03/09/2022] [Indexed: 11/26/2022] Open
Abstract
There is a high incidence of non-obese type 2 diabetes mellitus (non-obese-T2DM) cases, particularly in Asian countries, for which the pathogenesis remains mainly unclear. Interestingly, Goto-Kakizaki (GK) rats spontaneously develop insulin resistance (IR) and non-obese-T2DM, making them a lean diabetes model. Physical exercise is a non-pharmacological therapeutic approach to reduce adipose tissue mass, improving peripheral IR, glycemic control, and quality of life in obese animals or humans with T2DM. In this narrative review, we selected and analyzed the published literature on the effects of physical exercise on the metabolic features associated with non-obese-T2DM. Only randomized controlled trials with regular physical exercise training, freely executed physical activity, or skeletal muscle stimulation protocols in GK rats published after 2008 were included. The results indicated that exercise reduces plasma insulin levels, increases skeletal muscle glycogen content, improves exercise tolerance, protects renal and myocardial function, and enhances blood oxygen flow in GK rats.
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Affiliation(s)
- B.S.M. Galán
- Instituto de Atividade Física e Esportes, Universidade Cruzeiro do Sul, Brasil
| | - T.D.A. Serdan
- Instituto de Atividade Física e Esportes, Universidade Cruzeiro do Sul, Brasil; New York University, USA
| | - L.E. Rodrigues
- Instituto de Atividade Física e Esportes, Universidade Cruzeiro do Sul, Brasil
| | - R. Manoel
- Instituto de Atividade Física e Esportes, Universidade Cruzeiro do Sul, Brasil
| | - R. Gorjão
- Instituto de Atividade Física e Esportes, Universidade Cruzeiro do Sul, Brasil
| | - L.N. Masi
- Instituto de Atividade Física e Esportes, Universidade Cruzeiro do Sul, Brasil
| | - T.C. Pithon-Curi
- Instituto de Atividade Física e Esportes, Universidade Cruzeiro do Sul, Brasil
| | - R. Curi
- Instituto de Atividade Física e Esportes, Universidade Cruzeiro do Sul, Brasil; Instituto Butantan, Brasil
| | - S.M. Hirabara
- Instituto de Atividade Física e Esportes, Universidade Cruzeiro do Sul, Brasil
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4
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Chemical-Mediated Targeted Protein Degradation in Neurodegenerative Diseases. Life (Basel) 2021; 11:life11070607. [PMID: 34202541 PMCID: PMC8305580 DOI: 10.3390/life11070607] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/22/2021] [Accepted: 06/22/2021] [Indexed: 02/06/2023] Open
Abstract
Neurodegenerative diseases, including Alzheimer’s disease, Huntington’s disease, and Parkinson’s disease, are a class of diseases that lead to dysfunction of cognition and mobility. Aggregates of misfolded proteins such as β-amyloid, tau, α-synuclein, and polyglutamates are known to be among the main causes of neurodegenerative diseases; however, they are considered to be some of the most challenging drug targets because they cannot be modulated by conventional small-molecule agents. Recently, the degradation of target proteins by small molecules has emerged as a new therapeutic modality and has garnered the interest of the researchers in the pharmaceutical industry. Bifunctional molecules that recruit target proteins to a cellular protein degradation machinery, such as the ubiquitin–proteasome system and autophagy–lysosome pathway, have been designed. The representative targeted protein degradation technologies include molecular glues, proteolysis-targeting chimeras, hydrophobic tagging, autophagy-targeting chimeras, and autophagosome-tethering compounds. Although these modalities have been shown to degrade many disease-related proteins, such technologies are expected to be potentially important for neurogenerative diseases caused by protein aggregation. Herein, we review the recent progress in chemical-mediated targeted protein degradation toward the discovery of drugs for neurogenerative diseases.
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5
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Fiolek TJ, Magyar CL, Wall TJ, Davies SB, Campbell MV, Savich CJ, Tepe JJ, Mosey RA. Dihydroquinazolines enhance 20S proteasome activity and induce degradation of α-synuclein, an intrinsically disordered protein associated with neurodegeneration. Bioorg Med Chem Lett 2021; 36:127821. [PMID: 33513387 DOI: 10.1016/j.bmcl.2021.127821] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/05/2021] [Accepted: 01/18/2021] [Indexed: 02/02/2023]
Abstract
Aggregates or oligomeric forms of many intrinsically disordered proteins (IDPs), including α-synuclein, are hallmarks of neurodegenerative diseases, like Parkinson's and Alzheimer's disease, and key contributors to their pathogenesis. Due to their disordered nature and therefore lack of defined drug-binding pockets, IDPs are difficult targets for traditional small molecule drug design and are often referred to as "undruggable". The 20S proteasome is the main protease that targets IDPs for degradation and therefore small molecule 20S proteasome enhancement presents a novel therapeutic strategy by which these undruggable IDPs could be targeted. The concept of 20S activation is still relatively new, with few potent activators having been identified thus far. Herein, we synthesized and evaluated a library of dihydroquinazoline analogues and discovered several promising new 20S proteasome activators. Further testing of top hits revealed that they can enhance 20S mediated degradation of α-synuclein, the IDP associated with Parkinson's disease.
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Affiliation(s)
- Taylor J Fiolek
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, United States
| | - Christina L Magyar
- Department of Chemistry, Lake Superior State University, Sault Sainte Marie, MI 49783, United States
| | - Tyler J Wall
- Department of Chemistry, Lake Superior State University, Sault Sainte Marie, MI 49783, United States
| | - Steven B Davies
- Department of Chemistry, Lake Superior State University, Sault Sainte Marie, MI 49783, United States
| | - Molly V Campbell
- Department of Chemistry, Lake Superior State University, Sault Sainte Marie, MI 49783, United States
| | - Christopher J Savich
- Department of Chemistry, Lake Superior State University, Sault Sainte Marie, MI 49783, United States
| | - Jetze J Tepe
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, United States.
| | - R Adam Mosey
- Department of Chemistry, Lake Superior State University, Sault Sainte Marie, MI 49783, United States.
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Skariah G, Todd PK. Translational control in aging and neurodegeneration. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1628. [PMID: 32954679 DOI: 10.1002/wrna.1628] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/19/2020] [Accepted: 09/07/2020] [Indexed: 12/13/2022]
Abstract
Protein metabolism plays central roles in age-related decline and neurodegeneration. While a large body of research has explored age-related changes in protein degradation, alterations in the efficiency and fidelity of protein synthesis with aging are less well understood. Age-associated changes occur in both the protein synthetic machinery (ribosomal proteins and rRNA) and within regulatory factors controlling translation. At the same time, many of the interventions that prolong lifespan do so in part by pre-emptively decreasing protein synthesis rates to allow better harmonization to age-related declines in protein catabolism. Here we review the roles of translation regulation in aging, with a specific focus on factors implicated in age-related neurodegeneration. We discuss how emerging technologies such as ribosome profiling and superior mass spectrometric approaches are illuminating age-dependent mRNA-specific changes in translation rates across tissues to reveal a critical interplay between catabolic and anabolic pathways that likely contribute to functional decline. These new findings point to nodes in posttranscriptional gene regulation that both contribute to aging and offer targets for therapy. This article is categorized under: Translation > Translation Regulation Translation > Ribosome Biogenesis Translation > Translation Mechanisms.
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Affiliation(s)
- Geena Skariah
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
- Ann Arbor VA Healthcare System, Department of Veterans Affairs, Ann Arbor, Michigan, USA
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7
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Sakellari M, Chondrogianni N, Gonos ES. Protein synthesis inhibition induces proteasome assembly and function. Biochem Biophys Res Commun 2019; 514:224-230. [PMID: 31029420 DOI: 10.1016/j.bbrc.2019.04.114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 04/15/2019] [Indexed: 10/26/2022]
Abstract
Protein synthesis and degradation balance have a crucial role in maintenance of cellular homeostasis and function. The ubiquitin-proteasome system is one of the major cellular proteolytic machineries responsible for the removal of normal, abnormal, denatured or in general damaged proteins. Proteasome is a multisubunit enzyme that consists of the 20S core and the 19S regulatory complexes giving rise to multiple active forms. In the present study we investigated the crosstalk between protein synthesis and proteasome-mediated protein degradation. Pharmacological protein synthesis inhibition led to increased proteasome function and assembly of 30S/26S proteasome complexes, in human primary embryonic fibroblasts. The enhancement in proteasome function counted for the degradation of ubiquitinated, misfolded and oxidized proteins. Additionally, it was found that heat shock proteins 70 and 90 are probably involved in the elevated proteasome assembly. Our results provide an insight on how the mechanisms of protein synthesis, protein degradation and heat shock protein chaperones machinery interact under various cellular conditions.
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Affiliation(s)
- Marianthi Sakellari
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., Athens, 11635, Greece; Örebro University, Medical School, Örebro, 701 82, Sweden
| | - Niki Chondrogianni
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., Athens, 11635, Greece.
| | - Efstathios S Gonos
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., Athens, 11635, Greece; Örebro University, Medical School, Örebro, 701 82, Sweden.
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8
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Ubiquitin C-terminal hydrolase L1 (UCH-L1) loss causes neurodegeneration by altering protein turnover in the first postnatal weeks. Proc Natl Acad Sci U S A 2019; 116:7963-7972. [PMID: 30923110 DOI: 10.1073/pnas.1812413116] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Ubiquitin C-terminal hydrolase L1 (UCH-L1) is one of the most abundant and enigmatic enzymes of the CNS. Based on existing UCH-L1 knockout models, UCH-L1 is thought to be required for the maintenance of axonal integrity, but not for neuronal development despite its high expression in neurons. Several lines of evidence suggest a role for UCH-L1 in mUB homeostasis, although the specific in vivo substrate remains elusive. Since the precise mechanisms underlying UCH-L1-deficient neurodegeneration remain unclear, we generated a transgenic mouse model of UCH-L1 deficiency. By performing biochemical and behavioral analyses we can show that UCH-L1 deficiency causes an acceleration of sensorimotor reflex development in the first postnatal week followed by a degeneration of motor function starting at periadolescence in the setting of normal cerebral mUB levels. In the first postnatal weeks, neuronal protein synthesis and proteasomal protein degradation are enhanced, with endoplasmic reticulum stress, and energy depletion, leading to proteasomal impairment and an accumulation of nondegraded ubiquitinated protein. Increased protein turnover is associated with enhanced mTORC1 activity restricted to the postnatal period in UCH-L1-deficient brains. Inhibition of mTORC1 with rapamycin decreases protein synthesis and ubiquitin accumulation in UCH-L1-deficient neurons. Strikingly, rapamycin treatment in the first 8 postnatal days ameliorates the neurological phenotype of UCH-L1-deficient mice up to 16 weeks, suggesting that early control of protein homeostasis is imperative for long-term neuronal survival. In summary, we identified a critical presymptomatic period during which UCH-L1-dependent enhanced protein synthesis results in neuronal strain and progressive loss of neuronal function.
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9
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Castonguay D, Dufort-Gervais J, Ménard C, Chatterjee M, Quirion R, Bontempi B, Schneider JS, Arnsten AFT, Nairn AC, Norris CM, Ferland G, Bézard E, Gaudreau P, Lombroso PJ, Brouillette J. The Tyrosine Phosphatase STEP Is Involved in Age-Related Memory Decline. Curr Biol 2018; 28:1079-1089.e4. [PMID: 29576474 DOI: 10.1016/j.cub.2018.02.047] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/27/2017] [Accepted: 02/19/2018] [Indexed: 01/22/2023]
Abstract
Cognitive disabilities that occur with age represent a growing and expensive health problem. Age-associated memory deficits are observed across many species, but the underlying molecular mechanisms remain to be fully identified. Here, we report elevations in the levels and activity of the striatal-enriched phosphatase (STEP) in the hippocampus of aged memory-impaired mice and rats, in aged rhesus monkeys, and in people diagnosed with amnestic mild cognitive impairment (aMCI). The accumulation of STEP with aging is related to dysfunction of the ubiquitin-proteasome system that normally leads to the degradation of STEP. Higher level of active STEP is linked to enhanced dephosphorylation of its substrates GluN2B and ERK1/2, CREB inactivation, and a decrease in total levels of GluN2B and brain-derived neurotrophic factor (BDNF). These molecular events are reversed in aged STEP knockout and heterozygous mice, which perform similarly to young control mice in the Morris water maze (MWM) and Y-maze tasks. In addition, administration of the STEP inhibitor TC-2153 to old rats significantly improved performance in a delayed alternation T-maze memory task. In contrast, viral-mediated STEP overexpression in the hippocampus is sufficient to induce memory impairment in the MWM and Y-maze tests, and these cognitive deficits are reversed by STEP inhibition. In old LOU/C/Jall rats, a model of healthy aging with preserved memory capacities, levels of STEP and GluN2B are stable, and phosphorylation of GluN2B and ERK1/2 is unaltered. Altogether, these data suggest that elevated levels of STEP that appear with advancing age in several species contribute to the cognitive declines associated with aging.
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Affiliation(s)
- David Castonguay
- Department of Pharmacology and Physiology, Université de Montréal, and Hôpital du Sacré-Coeur de Montréal Research Center, Montreal, QC, Canada
| | - Julien Dufort-Gervais
- Department of Pharmacology and Physiology, Université de Montréal, and Hôpital du Sacré-Coeur de Montréal Research Center, Montreal, QC, Canada
| | - Caroline Ménard
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada; Department of Medecine, Université de Montréal, Centre Hospitalier de l'Université de Montréal Research Center, Montreal, QC, Canada
| | - Manavi Chatterjee
- Child Study Center, Yale University School of Medicine, New Haven, CT, USA
| | - Rémi Quirion
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
| | - Bruno Bontempi
- Université de Bordeaux, UMR 5293, Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
| | - Jay S Schneider
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Amy F T Arnsten
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Angus C Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Christopher M Norris
- Department of Molecular and Biomedical Pharmacology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Guylaine Ferland
- Department of Nutrition, Université de Montréal, and Institut de Cardiologie de Montréal, Montreal, QC, Canada
| | - Erwan Bézard
- Université de Bordeaux, UMR 5293, Bordeaux, France; CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
| | - Pierrette Gaudreau
- Department of Medecine, Université de Montréal, Centre Hospitalier de l'Université de Montréal Research Center, Montreal, QC, Canada
| | - Paul J Lombroso
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA; Child Study Center, Yale University School of Medicine, New Haven, CT, USA.
| | - Jonathan Brouillette
- Department of Pharmacology and Physiology, Université de Montréal, and Hôpital du Sacré-Coeur de Montréal Research Center, Montreal, QC, Canada; Child Study Center, Yale University School of Medicine, New Haven, CT, USA.
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10
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Abstract
Maintaining synaptic integrity and function depends on the continuous removal and degradation of aged or damaged proteins. Synaptic protein degradation has received considerable attention in the context of synaptic plasticity and growing interest in relation to neurodegenerative and other disorders. Conversely, less attention has been given to constitutive, ongoing synaptic protein degradation and the roles canonical degradation pathways play in these processes. Here we briefly review recent progress on this topic and new experimental approaches which have expedited such progress and highlight several emerging principles. These include the realization that synaptic proteins typically have unusually long lifetimes, as might be expected from the remote locations of most synaptic sites; the possibility that degradation pathways can change with time from synthesis, cellular context, and physiological input; and that degradation pathways, other than ubiquitin-proteasomal-mediated degradation, might play key roles in constitutive protein degradation at synaptic sites. Finally, we point to the importance of careful experimental design and sufficiently sensitive techniques for studying synaptic protein degradation, which bring into account their slow turnover rates and complex life cycles.
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Affiliation(s)
- Laurie D Cohen
- Technion Faculty of Medicine, Rappaport Institute and Network Biology Research Laboratories, Technion City, Haifa, 32000, Israel
| | - Noam E Ziv
- Technion Faculty of Medicine, Rappaport Institute and Network Biology Research Laboratories, Technion City, Haifa, 32000, Israel
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11
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Chintalapudi SR, Jablonski MM. Systems Genetics Analysis to Identify the Genetic Modulation of a Glaucoma-Associated Gene. Methods Mol Biol 2017; 1488:391-417. [PMID: 27933535 DOI: 10.1007/978-1-4939-6427-7_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Loss of retinal ganglion cells (RGCs) is one of the hallmarks of retinal neurodegenerative diseases, glaucoma being one of the most common. Recently, γ-synuclein (SNCG) was shown to be highly expressed in the somas and axons of RGCs. In various mouse models of glaucoma, downregulation of Sncg gene expression correlates with RGC loss. To investigate the regulation of Sncg in RGCs, we used a systems genetics approach to identify a gene that modulates the expression of Sncg, followed by confirmatory studies in both healthy and diseased retinas. We found that chromosome 1 harbors an eQTL that modulates the expression of Sncg in the mouse retina and identified Pfdn2 as the candidate upstream modulator of Sncg expression. Downregulation of Pfdn2 in enriched RGCs causes a concomitant reduction in Sncg. In this chapter, we describe our strategy and methods for identifying and confirming a genetic modulation of a glaucoma-associated gene. A similar method can be applied to other genes expressed in other tissues.
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Affiliation(s)
- Sumana R Chintalapudi
- Department of Anatomy and Neurobiology, Hamilton Eye Institute, The University of Tennessee Health Science Center, 930 Madison Ave., Suite 710, Memphis, TN, 38163, USA
| | - Monica M Jablonski
- Department of Ophthalmology, Hamilton Eye Institute, The University of Tennessee Health Science Center, 930 Madison Ave., Suite 710, Memphis, TN, 38163, USA. .,Department of Anatomy and Neurobiology, Hamilton Eye Institute, The University of Tennessee Health Science Center, 930 Madison Ave., Suite 710, Memphis, TN, 38163, USA. .,Department of Pharmaceutical Sciences, Hamilton Eye Institute, The University of Tennessee Health Science Center, 930 Madison Ave., Suite 710, Memphis, TN, 38163, USA.
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12
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Hakim V, Cohen LD, Zuchman R, Ziv T, Ziv NE. The effects of proteasomal inhibition on synaptic proteostasis. EMBO J 2016; 35:2238-2262. [PMID: 27613546 PMCID: PMC5069550 DOI: 10.15252/embj.201593594] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 08/08/2016] [Indexed: 01/03/2023] Open
Abstract
Synaptic function crucially depends on uninterrupted synthesis and degradation of synaptic proteins. While much has been learned on synaptic protein synthesis, little is known on the routes by which synaptic proteins are degraded. Here we systematically studied how inhibition of the ubiquitin-proteasome system (UPS) affects the degradation rates of thousands of neuronal and synaptic proteins. We identified a group of proteins, including several proteins related to glutamate receptor trafficking, whose degradation rates were significantly slowed by UPS inhibition. Unexpectedly, however, degradation rates of most synaptic proteins were not significantly affected. Interestingly, many of the differential effects of UPS inhibition were readily explained by a quantitative framework that considered known metabolic turnover rates for the same proteins. In contrast to the limited effects on protein degradation, UPS inhibition profoundly and preferentially suppressed the synthesis of a large number of synaptic proteins. Our findings point to the importance of the UPS in the degradation of certain synaptic proteins, yet indicate that under basal conditions most synaptic proteins might be degraded through alternative pathways.
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Affiliation(s)
- Vicky Hakim
- The Rappaport Faculty of Medicine and Research Institute, Haifa, Israel.,Network Biology Research Laboratories, Technion - Israel Institute of Technology, Haifa, Israel
| | - Laurie D Cohen
- The Rappaport Faculty of Medicine and Research Institute, Haifa, Israel.,Network Biology Research Laboratories, Technion - Israel Institute of Technology, Haifa, Israel
| | - Rina Zuchman
- Smoler Proteomics Center, Faculty of Biology, Technion, Haifa, Israel
| | - Tamar Ziv
- Smoler Proteomics Center, Faculty of Biology, Technion, Haifa, Israel
| | - Noam E Ziv
- The Rappaport Faculty of Medicine and Research Institute, Haifa, Israel .,Network Biology Research Laboratories, Technion - Israel Institute of Technology, Haifa, Israel
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13
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Chintalapudi SR, Morales-Tirado VM, Williams RW, Jablonski MM. Multipronged approach to identify and validate a novel upstream regulator of Sncg in mouse retinal ganglion cells. FEBS J 2016; 283:678-93. [PMID: 26663874 DOI: 10.1111/febs.13620] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/22/2015] [Accepted: 12/03/2015] [Indexed: 11/26/2022]
Abstract
Loss of retinal ganglion cells (RGCs) is one of the hallmarks of retinal neurodegenerative diseases, glaucoma being one of the most common. Mechanistic studies on RGCs are hindered by the lack of sufficient primary cells and consensus regarding their signature markers. Recently, γ-synuclein (SNCG) has been shown to be highly expressed in the somas and axons of RGCs. In various mouse models of glaucoma, downregulation of Sncg gene expression correlates with RGC loss. To investigate the role of Sncg in RGCs, we used a novel systems genetics approach to identify a gene that modulates Sncg expression, followed by confirmatory studies in both healthy and diseased retinae. We found that chromosome 1 harbors an expression quantitative trait locus that modulates Sncg expression in the mouse retina, and identified the prefoldin-2 (PFDN2) gene as the candidate upstream modulator of Sncg expression. Our immunohistochemical analyses revealed similar expression patterns in both mouse and human healthy retinae, with PFDN2 colocalizing with SNCG in RGCs and their axons. In contrast, in retinae from glaucoma subjects, SNCG levels were significantly reduced, although PFDN2 levels were maintained. Using a novel flow cytometry-based RGC isolation method, we obtained viable populations of murine RGCs. Knocking down Pfdn2 expression in primary murine RGCs significantly reduced Sncg expression, confirming that Pfdn2 regulates Sncg expression in murine RGCs. Gene Ontology analysis indicated shared mitochondrial function associated with Sncg and Pfdn2. These data solidify the relationship between Sncg and Pfdn2 in RGCs, and provide a novel mechanism for maintaining RGC health.
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Affiliation(s)
- Sumana R Chintalapudi
- Department of Ophthalmology, The Hamilton Eye Institute, The University of Tennessee Health Science Center, Memphis, TN, USA.,Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Vanessa M Morales-Tirado
- Department of Ophthalmology, The Hamilton Eye Institute, The University of Tennessee Health Science Center, Memphis, TN, USA.,Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA.,Department of Microbiology, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Robert W Williams
- Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA.,Department of Genetics, Genomics and Informatics, The University of Tennessee Health Science Center, Memphis, TN, USA
| | - Monica M Jablonski
- Department of Ophthalmology, The Hamilton Eye Institute, The University of Tennessee Health Science Center, Memphis, TN, USA.,Department of Anatomy and Neurobiology, The University of Tennessee Health Science Center, Memphis, TN, USA
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14
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Liepe J, Holzhütter HG, Kloetzel PM, Stumpf MPH, Mishto M. Modelling proteasome and proteasome regulator activities. Biomolecules 2014; 4:585-99. [PMID: 24970232 PMCID: PMC4101499 DOI: 10.3390/biom4020585] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/28/2014] [Accepted: 05/30/2014] [Indexed: 02/07/2023] Open
Abstract
Proteasomes are key proteases involved in a variety of processes ranging from the clearance of damaged proteins to the presentation of antigens to CD8+ T-lymphocytes. Which cleavage sites are used within the target proteins and how fast these proteins are degraded have a profound impact on immune system function and many cellular metabolic processes. The regulation of proteasome activity involves different mechanisms, such as the substitution of the catalytic subunits, the binding of regulatory complexes to proteasome gates and the proteasome conformational modifications triggered by the target protein itself. Mathematical models are invaluable in the analysis; and potentially allow us to predict the complex interactions of proteasome regulatory mechanisms and the final outcomes of the protein degradation rate and MHC class I epitope generation. The pioneering attempts that have been made to mathematically model proteasome activity, cleavage preference variation and their modification by one of the regulatory mechanisms are reviewed here.
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Affiliation(s)
- Juliane Liepe
- Theoretical Systems Biology, Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, UK.
| | | | - Peter M Kloetzel
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany.
| | - Michael P H Stumpf
- Theoretical Systems Biology, Division of Molecular Biosciences, Imperial College London, London SW7 2AZ, UK.
| | - Michele Mishto
- Institute of Biochemistry, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany.
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15
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Palanca A, Casafont I, Berciano MT, Lafarga M. Proteasome inhibition induces DNA damage and reorganizes nuclear architecture and protein synthesis machinery in sensory ganglion neurons. Cell Mol Life Sci 2014; 71:1961-75. [PMID: 24061536 PMCID: PMC11113442 DOI: 10.1007/s00018-013-1474-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 09/02/2013] [Accepted: 09/10/2013] [Indexed: 11/24/2022]
Abstract
Bortezomib is a reversible proteasome inhibitor used as an anticancer drug. However, its clinical use is limited since it causes peripheral neurotoxicity. We have used Sprague-Dawley rats as an animal model to investigate the cellular mechanisms affected by both short-term and chronic bortezomib treatments in sensory ganglia neurons. Proteasome inhibition induces dose-dependent alterations in the architecture, positioning, shape and polarity of the neuronal nucleus. It also produces DNA damage without affecting neuronal survival, and severe disruption of the protein synthesis machinery at the central cytoplasm accompanied by decreased expression of the brain-derived neurotrophic factor. As a compensatory or adaptive survival response against proteotoxic stress caused by bortezomib treatment, sensory neurons preserve basal levels of transcriptional activity, up-regulate the expression of proteasome subunit genes, and generate a new cytoplasmic perinuclear domain for protein synthesis. We propose that proteasome activity is crucial for controlling nuclear architecture, DNA repair and the organization of the protein synthesis machinery in sensory neurons. These neurons are primary targets of bortezomib neurotoxicity, for which reason their dysfunction may contribute to the pathogenesis of the bortezomib-induced peripheral neuropathy in treated patients.
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Affiliation(s)
- Ana Palanca
- Department of Anatomy and Cell Biology, Faculty of Medicine and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), University of Cantabria-IFIMAV, Avd. Cardenal Herrera Oria s/n, 39011 Santander, Spain
| | - Iñigo Casafont
- Department of Anatomy and Cell Biology, Faculty of Medicine and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), University of Cantabria-IFIMAV, Avd. Cardenal Herrera Oria s/n, 39011 Santander, Spain
| | - María T. Berciano
- Department of Anatomy and Cell Biology, Faculty of Medicine and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), University of Cantabria-IFIMAV, Avd. Cardenal Herrera Oria s/n, 39011 Santander, Spain
| | - Miguel Lafarga
- Department of Anatomy and Cell Biology, Faculty of Medicine and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), University of Cantabria-IFIMAV, Avd. Cardenal Herrera Oria s/n, 39011 Santander, Spain
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16
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Dasuri K, Zhang L, Keller JN. Oxidative stress, neurodegeneration, and the balance of protein degradation and protein synthesis. Free Radic Biol Med 2013; 62:170-185. [PMID: 23000246 DOI: 10.1016/j.freeradbiomed.2012.09.016] [Citation(s) in RCA: 260] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/05/2012] [Accepted: 09/11/2012] [Indexed: 12/12/2022]
Abstract
Oxidative stress occurs in a variety of disease settings and is strongly linked to the development of neuron death and neuronal dysfunction. Cells are equipped with numerous pathways to prevent the genesis, as well as the consequences, of oxidative stress in the brain. In this review we discuss the various forms and sources of oxidative stress in the brain and briefly discuss some of the complexities in detecting the presence of oxidative stress. We then focus the review on the interplay between the diverse cellular proteolytic pathways and their roles in regulating oxidative stress in the brain. Additionally, we discuss the involvement of protein synthesis in regulating the downstream effects of oxidative stress. Together, these components of the review demonstrate that the removal of damaged proteins by effective proteolysis and the synthesis of new and protective proteins are vital in the preservation of brain homeostasis during periods of increased levels of reactive oxygen species. Last, studies from our laboratory and others have demonstrated that protein synthesis is intricately linked to the rates of protein degradation, with impairment of protein degradation sufficient to decrease the rates of protein synthesis, which has important implications for successfully responding to periods of oxidative stress. Specific neurodegenerative diseases, including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and stroke, are discussed in this context. Taken together, these findings add to our understanding of how oxidative stress is effectively managed in the healthy brain and help elucidate how impairments in proteolysis and/or protein synthesis contribute to the development of neurodegeneration and neuronal dysfunction in a variety of clinical settings.
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Affiliation(s)
- Kalavathi Dasuri
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
| | - Le Zhang
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
| | - Jeffrey N Keller
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
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17
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Milner E, Gutter-Kapon L, Bassani-Strenberg M, Barnea E, Beer I, Admon A. The effect of proteasome inhibition on the generation of the human leukocyte antigen (HLA) peptidome. Mol Cell Proteomics 2013; 12:1853-64. [PMID: 23538226 DOI: 10.1074/mcp.m112.026013] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The Major histocompatibility complex (MHC) class I peptidome is thought to be generated mostly through proteasomal degradation of cellular proteins, a notion that is based on the alterations in presentation of selected peptides following proteasome inhibition. We evaluated the effects of proteasome inhibitors, epoxomicin and bortezomib, on human cultured cancer cells. Because the inhibitors did not reduce the level of presentation of the cell surface human leukocyte antigen (HLA) molecules, we followed their effects on the rates of synthesis of both HLA peptidome and proteome of the cells, using dynamic stable isotope labeling in tissue culture (dynamic-SILAC). The inhibitors reduced the rates of synthesis of most cellular proteins and HLA peptides, yet the synthesis rates of some of the proteins and HLA peptides was not decreased by the inhibitors and of some even increased. Therefore, we concluded that the inhibitors affected the production of the HLA peptidome in a complex manner, including modulation of the synthesis rates of the source proteins of the HLA peptides, in addition to their effect on their degradation. The collected data may suggest that the current reliance on proteasome inhibition may overestimate the centrality of the proteasome in the generation of the MHC peptidome. It is therefore suggested that the relative contribution of the proteasomal and nonproteasomal pathways to the production of the MHC peptidome should be revaluated in accordance with the inhibitors effects on the synthesis rates of the source proteins of the MHC peptides.
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Affiliation(s)
- Elena Milner
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
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18
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Oxidative Damage to RNA in Aging and Neurodegenerative Disorders. Neurotox Res 2012; 22:231-48. [DOI: 10.1007/s12640-012-9331-x] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2012] [Revised: 05/13/2012] [Accepted: 05/17/2012] [Indexed: 12/14/2022]
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19
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Dysfunction of the ubiquitin-proteasome system in the cerebellum of aging Ts65Dn mice. Exp Neurol 2011; 232:114-8. [PMID: 21867700 DOI: 10.1016/j.expneurol.2011.08.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 07/22/2011] [Accepted: 08/08/2011] [Indexed: 01/09/2023]
Abstract
In the cerebellum of adult-aging Ts65Dn mice, a murine model of Down syndrome, Purkinje cells undergo degeneration. Searching for the cause of Purkinje cell degeneration, we have studied the ubiquitin-proteasome system (UPS) in the cerebellum of aging Ts65Dn mice. Inhibition of UPS is sufficient to induce neuron degeneration and death. Proteasome chymotrypsin-like proteolytic activity was reduced by 35% in the cerebellum of Ts65Dn mice in comparison with euploid animals. Accordingly, Western blot analysis of ubiquitin showed an increase in ubiquitinated proteins. Immunocytochemistry for ubiquitin revealed strongly positive intranuclear inclusions in Purkinje cells and large neurons of cerebellar nuclei. The Western blot analysis of ubiquitin in nuclear protein extracts confirmed the increase of ubiquitinated proteins in the cell nuclei. After FUS immunocytochemistry, large intranuclear inclusions were visible in Purkinje cells and large neurons of cerebellar nuclei in Ts65Dn mice. Together, data indicate a possible role for proteasome inhibition in the cerebellar neurodegeneration in Ts65Dn mice.
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20
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Dasuri K, Ebenezer PJ, Uranga RM, Gavilán E, Zhang L, Fernandez-Kim SOK, Bruce-Keller AJ, Keller JN. Amino acid analog toxicity in primary rat neuronal and astrocyte cultures: implications for protein misfolding and TDP-43 regulation. J Neurosci Res 2011; 89:1471-7. [PMID: 21608013 DOI: 10.1002/jnr.22677] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 03/20/2011] [Accepted: 04/03/2011] [Indexed: 12/13/2022]
Abstract
Amino acid analogs promote translational errors that result in aberrant protein synthesis and have been used to understand the effects of protein misfolding in a variety of physiological and pathological settings. TDP-43 is a protein that is linked to protein aggregation and toxicity in a variety of neurodegenerative diseases. This study exposed primary rat neurons and astrocyte cultures to established amino acid analogs (canavanine and azetidine-2-carboxylic acid) and showed that both cell types undergo a dose-dependent increase in toxicity, with neurons exhibiting a greater degree of toxicity compared with astrocytes. Neurons and astrocytes exhibited similar increases in ubiquitinated and oxidized protein following analog treatment. Analog treatment increased heat shock protein (Hsp) levels in both neurons and astrocytes. In neurons, and to a lesser extent astrocytes, the levels of TDP-43 increased in response to analog treatment. Taken together, these data indicate that neurons exhibit preferential toxicity and alterations in TDP-43 in response to increased protein misfolding compared with astrocytes.
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Affiliation(s)
- Kalavathi Dasuri
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA 70808-4124, USA
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21
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Lorenc-Koci E, Lenda T, Antkiewicz-Michaluk L, Wardas J, Domin H, Smiałowska M, Konieczny J. Different effects of intranigral and intrastriatal administration of the proteasome inhibitor lactacystin on typical neurochemical and histological markers of Parkinson's disease in rats. Neurochem Int 2011; 58:839-49. [PMID: 21419185 DOI: 10.1016/j.neuint.2011.03.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 03/08/2011] [Accepted: 03/09/2011] [Indexed: 12/21/2022]
Abstract
Impairment of the ubiquitin-proteasome system, responsible for clearing of misfolded and unwanted proteins, has been implicated in the loss of nigrostriatal dopaminergic neurons characteristic of Parkinson's disease (PD). Recently, proteasome inhibitors have been used to model parkinsonian-like changes in animals. In the present study, the effects of intrastriatal and intranigral injections of the selective proteasome inhibitor lactacystin on key markers of PD were examined in Wistar rats. Comparisons of these two different routes of lactacystin administration revealed that only a unilateral, intranigral injection of lactacystin at a dose of 0.5, 1, 2.5 and 5 μg/2 μl produced after 7 days distinct decreases in the concentrations of dopamine (DA) and its metabolites (DOPAC, 3-MT, HVA) in the ipsilateral striatum. The used doses of lactacystin (except for 0.5 μg/2 μl) significantly accelerated DA catabolism, i.e. the total, oxidative MAO-dependent and COMT-catalyzed pathways, as assessed by HVA/DA, DOPAC/DA and 3-MT/DA ratios, respectively, in the ipsilateral striatum. Such alterations were not observed in the striatal DA content and catabolism either 7, 14 or 21 days after a unilateral, intrastriatal high-dose lactacystin injection (5 and 10 μg/2 μl). Intranigrally administered lactacystin (1 μg/2 μl) caused a marked decline of tyrosine hydroxylase (TH) and α-synuclein protein levels in that structure. Neither TH nor α-synuclein protein levels in the substantia nigra (SN) were affected by high lactacystin doses injected intrastriatally. Moreover, stereological counting of TH-immunoreactive neurons and autoradiographic analysis of [(3)H]GBR 12,935 binding to dopamine transporter confirmed a loss of nigrostriatal dopaminergic neurons after an intranigral lactacystin (1 and 2.5 μg/2 μl) injection. An appearance of cardinal neurochemical and histological changes of parkinsonian type only after intranigral lactacystin injection indicates that DA cell bodies in the SN, but not DA terminals in the striatum are susceptible to proteasome inhibition.
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Affiliation(s)
- Elżbieta Lorenc-Koci
- Department of Neuro-Psychopharmacology, Institute of Pharmacology, Polish Academy of Sciences, 12, Smętna St., PL-31-343 Kraków, Poland.
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22
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Dasuri K, Ebenezer PJ, Zhang L, Fernandez-Kim SO, Uranga RM, Gavilán E, Di Blasio A, Keller JN. Selective vulnerability of neurons to acute toxicity after proteasome inhibitor treatment: implications for oxidative stress and insolubility of newly synthesized proteins. Free Radic Biol Med 2010; 49:1290-7. [PMID: 20678570 PMCID: PMC3175605 DOI: 10.1016/j.freeradbiomed.2010.07.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 07/13/2010] [Accepted: 07/19/2010] [Indexed: 12/19/2022]
Abstract
Maintaining protein homeostasis is vital to cell viability, with numerous studies demonstrating a role for proteasome inhibition occurring during the aging of a variety of tissues and, presumably, contributing to the disruption of cellular homeostasis during aging. In this study we sought to elucidate the differences between neurons and astrocytes in regard to basal levels of protein synthesis, proteasome-mediated protein degradation, and sensitivity to cytotoxicity after proteasome inhibitor treatment. In these studies we demonstrate that neurons have an increased vulnerability, compared to astrocyte cultures, to proteasome-inhibitor-induced cytotoxicity. No significant difference was observed between these two cell types in regard to the basal rates of protein synthesis, or basal rates of protein degradation, in the pool of short-lived proteins. After proteasome inhibitor treatment neuronal crude lysates were observed to undergo greater increases in the levels of ubiquitinated and oxidized proteins and selectively exhibited increased levels of newly synthesized proteins accumulating within the insoluble protein pool, compared to astrocytes. Together, these data suggest a role for increased oxidized proteins and sequestration of newly synthesized proteins in the insoluble protein pool, as potential mediators of the selective neurotoxicity after proteasome inhibitor treatment. The implications for neurons exhibiting increased sensitivity to acute proteasome inhibitor exposure, and the corresponding changes in protein homeostasis observed after proteasome inhibition, are discussed in the context of both aging and age-related disorders of the nervous system.
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Affiliation(s)
- Kalavathi Dasuri
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Philip J. Ebenezer
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Le Zhang
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Sun Ok Fernandez-Kim
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Romina M. Uranga
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca,Argentina
| | - Elena Gavilán
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Alessia Di Blasio
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
| | - Jeffrey N Keller
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, Louisiana, USA
- Corresponding author: Dr Jeffrey N. Keller, Pennington Biomedical Research Center/LSU System, 6400 Perkins Road, Baton Rouge, LA 70808-4124, (P): 225-763-3190; (E):
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23
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Bitto A, Sell C, Crowe E, Lorenzini A, Malaguti M, Hrelia S, Torres C. Stress-induced senescence in human and rodent astrocytes. Exp Cell Res 2010; 316:2961-8. [PMID: 20620137 DOI: 10.1016/j.yexcr.2010.06.021] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 06/24/2010] [Accepted: 06/26/2010] [Indexed: 01/18/2023]
Abstract
There is an increasing awareness that astrocytes, the most abundant cell type in the central nervous system, are critical mediators of brain homeostasis, playing multifunctional roles including buffering potassium ions, maintaining the blood-brain barrier, releasing growth factors, and regulating neurotransmitter levels. Defects in astrocyte function have been implicated in a variety of diseases including age-related diseases such Alzheimer's disease and Parkinson's disease. However, little is known about the age-related changes that occur in astrocytes and if these cells are able to generate a senescent phenotype in response to stress. In this report we have examined whether astrocytes can initiate a senescence program similar to that described in other cell types in response to a variety of stresses. Our results indicate that after oxidative stress, proteasome inhibition, or exhausted replication, human and mouse astrocytes show changes in several established markers of cellular senescence. Astrocytes appear to be more sensitive to oxidative stress than fibroblasts, suggesting that stress-induced senescence may be more pronounced in the brain than in other tissues.
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Affiliation(s)
- Alessandro Bitto
- Department of Pathology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
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24
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Pechmann S, Vendruscolo M. Derivation of a solubility condition for proteins from an analysis of the competition between folding and aggregation. MOLECULAR BIOSYSTEMS 2010; 6:2490-7. [DOI: 10.1039/c005160h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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25
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Zhang L, Ebenezer PJ, Dasuri K, Bruce-Keller AJ, Liu Y, Keller JN. Proteasome inhibition modulates kinase activation in neural cells: relevance to ubiquitination, ribosomes, and survival. J Neurosci Res 2009; 87:3231-8. [PMID: 19565657 DOI: 10.1002/jnr.22147] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In this study we examined whether established signal transduction cascades, p44/42 mitogen-activated protein kinase (ERK1/2) and Jun N-terminal kinases (JNK) pathways, are altered in N2a neural cells in response to proteasome inhibition. Additionally, we sought to elucidate the relative contribution of these signal transduction pathways to the multiple downstream effects of proteasome inhibition. Our data indicate that ERK1/2 and JNK are activated in response to proteasome inhibition. Washout of proteasome inhibitor (MG132) results in an enhancement of ERK1/2 activation and amelioration of JNK activation. Treatment with an established MAPK inhibitor resulted in an increase in proteasome inhibitor toxicity, and incubation with JNK inhibitor was observed to attenuate proteasome inhibitor toxicity significantly. Subsequent studies demonstrated that inhibition of ERK1/2 and JNK activity does not alter the gross increase in ubiquitinated protein following proteasome inhibitor administration. Similarly, ERK1/2 and JNK activity do not appear to play a role in the disruption of polysomes following proteasome inhibitor administration in neural cells. Together these data indicate that ERK1/2 and JNK activation may play differential roles in modulating neurochemical disturbances and neurotoxicity induced by proteasome inhibition.
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Affiliation(s)
- Le Zhang
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, Louisiana 70808-4124, USA
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26
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Jüch M, Smalla KH, Kähne T, Lubec G, Tischmeyer W, Gundelfinger ED, Engelmann M. Congenital lack of nNOS impairs long-term social recognition memory and alters the olfactory bulb proteome. Neurobiol Learn Mem 2009; 92:469-84. [DOI: 10.1016/j.nlm.2009.06.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 05/19/2009] [Accepted: 06/10/2009] [Indexed: 12/21/2022]
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27
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Zhang L, Ebenezer PJ, Dasuri K, Bruce-Keller AJ, Fernandez-Kim SO, Liu Y, Keller JN. Activation of PERK kinase in neural cells by proteasome inhibitor treatment. J Neurochem 2009; 112:238-45. [PMID: 19860852 DOI: 10.1111/j.1471-4159.2009.06448.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Inhibition of the proteasome proteolytic pathway occurs as the result of normal aging, as well as in a variety of neurodegenerative conditions, and is believed to promote cellular toxicity in each of these conditions through diverse mechanisms. In the present study, we examined whether proteasome inhibition alters the protein kinase receptor-like endoplasmic reticulum kinase (PERK). Our studies demonstrate that proteasome inhibitors induce the transient activation of PERK in both primary rat neurons as well as the N2a neural cell line. Experiments with siRNA to PERK demonstrated that the modulation of PERK was not significant involved in regulating toxicity, ubiquitinated protein levels, or ribosome perturbations in response to proteasome inhibitor treatment. Surprisingly, PERK was observed to be involved in the up-regulation of p38 kinase following proteasome inhibitor treatment. Taken together, these data demonstrate the ability of proteasome inhibition to activate PERK and demonstrate evidence for novel cross-talk between PERK and the activation of p38 kinase in neural cells following proteasome inhibition. Taken together, these data have implications for understanding the basis by which proteasome inhibition alters neural homeostasis, and the basis by which cell signaling cascades are regulated by proteasome inhibition.
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Affiliation(s)
- Le Zhang
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, Louisiana, USA
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28
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Sun X, Wolf ME. Nucleus accumbens neurons exhibit synaptic scaling that is occluded by repeated dopamine pre-exposure. Eur J Neurosci 2009; 30:539-50. [PMID: 19674091 DOI: 10.1111/j.1460-9568.2009.06852.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Synaptic scaling has been proposed as a form of plasticity that may contribute to drug addiction but it has not been previously demonstrated in the nucleus accumbens (NAc), a critical region for addiction. Here we demonstrate bidirectional synaptic scaling in postnatal rat NAc neurons that were co-cultured with prefrontal cortical neurons to restore excitatory input. Prolonged activity blockade (1-3 days) with an AMPA receptor antagonist increased cell surface (synaptic and extrasynaptic) glutamate receptor 1 (GluR1) and GluR2 but not GluR3, as well as GluR1/2 co-localization on the cell surface and total GluR1 and GluR2 protein levels. A prolonged increase in activity (bicuculline, 48 h) produced opposite effects. These results suggest that GluR1/2-containing AMPA receptors undergo synaptic scaling in NAc neurons. GluR1 and GluR2 surface expression was also increased by tetrodotoxin alone or in combination with an N-methyl-d-aspartate receptor or AMPA receptor antagonist but not by the l-type Ca(2+) channel antagonist nifedipine. A cobalt-quenching assay confirmed the immunocytochemical results indicating that synaptic scaling after activity blockade did not involve a change in abundance of GluR2-lacking AMPA receptors. Increased AMPA receptor surface expression after activity blockade required protein synthesis and was occluded by inhibition of the ubiquitin-proteasome system. Repeated dopamine (DA) treatment, which leads to upregulation of surface GluR1 and GluR2, occluded activity blockade-induced synaptic scaling. These latter results indicate an interaction between cellular mechanisms involved in synaptic scaling and adaptive mechanisms triggered by repeated DA receptor stimulation, suggesting that synaptic scaling may not function normally after exposure to DA-releasing drugs such as cocaine.
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Affiliation(s)
- Xiu Sun
- Department of Neuroscience, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
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29
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RNA oxidation in Alzheimer disease and related neurodegenerative disorders. Acta Neuropathol 2009; 118:151-66. [PMID: 19271225 DOI: 10.1007/s00401-009-0508-1] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Revised: 02/20/2009] [Accepted: 02/24/2009] [Indexed: 10/21/2022]
Abstract
RNA oxidation and its biological effects are less well studied compared to DNA oxidation. However, RNA may be more susceptible to oxidative insults than DNA, for RNA is largely single-stranded and its bases are not protected by hydrogen bonding and less protected by specific proteins. Also, cellular RNA locates in the vicinity of mitochondria, the primary source of reactive oxygen species. Oxidative modification can occur not only in protein-coding RNAs, but also in non-coding RNAs that have been recently revealed to contribute towards the complexity of the mammalian brain. Damage to coding and non-coding RNAs will cause errors in proteins and disturbances in the regulation of gene expression. While less lethal than mutations in the genome and not inheritable, such sublethal damage to cells might be associated with underlying mechanisms of degeneration, especially age-associated neurodegeneration that is commonly found in the elderly population. Indeed, oxidative RNA damage has been described recently in most of the common neurodegenerative disorders including Alzheimer disease, Parkinson disease, dementia with Lewy bodies and amyotrophic lateral sclerosis. Of particular interest, the accumulating evidence obtained from studies on either human samples or experimental models coincidentally suggests that oxidative RNA damage is a feature in vulnerable neurons at early-stage of these neurodegenerative disorders, indicating that RNA oxidation actively contributes to the onset or the development of the disorders. Further investigations aimed at understanding of the processing mechanisms related to oxidative RNA damage and its consequences may provide significant insights into the pathogenesis of neurodegenerative disorders and lead to better therapeutic strategies.
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30
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Chiang MC, Chen HM, Lai HL, Chen HW, Chou SY, Chen CM, Tsai FJ, Chern Y. The A2A adenosine receptor rescues the urea cycle deficiency of Huntington's disease by enhancing the activity of the ubiquitin-proteasome system. Hum Mol Genet 2009; 18:2929-42. [PMID: 19443488 DOI: 10.1093/hmg/ddp230] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion in the Huntingtin (Htt) gene. The resultant mutant Htt protein (mHtt) forms aggregates in the brain and several peripheral tissues (e.g. the liver) and causes devastating neuronal degeneration. Metabolic defects resulting from Htt aggregates in peripheral tissues also contribute to HD pathogenesis. Simultaneous improvement of defects in both the CNS and peripheral tissues is thus the most effective therapeutic strategy and is highly desirable. We earlier showed that an agonist of the A(2A) adenosine receptor (A(2A) receptor), CGS21680 (CGS), attenuates neuronal symptoms of HD. We found herein that the A(2A) receptor also exists in the liver, and that CGS ameliorated the urea cycle deficiency by reducing mHtt aggregates in the liver. By suppressing aggregate formation, CGS slowed the hijacking of a crucial transcription factor (HSF1) and two protein chaperons (Hsp27 and Hsp70) into hepatic Htt aggregates. Moreover, the abnormally high levels of high-molecular-mass ubiquitin conjugates in the liver of an HD mouse model (R6/2) were also ameliorated by CGS. The protective effect of CGS against mHtt-induced aggregate formation was reproduced in two cells lines and was prevented by an antagonist of the A(2A) receptor and a protein kinase A (PKA) inhibitor. Most importantly, the mHtt-induced suppression of proteasome activity was also normalized by CGS through PKA. Our findings reveal a novel therapeutic pathway of A(2A) receptors in HD and further strengthen the concept that the A(2A) receptor can be a drug target in treating HD.
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Affiliation(s)
- Ming-Chang Chiang
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei 115, Taiwan, Republic of China
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31
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Mozhui K, Ciobanu DC, Schikorski T, Wang X, Lu L, Williams RW. Dissection of a QTL hotspot on mouse distal chromosome 1 that modulates neurobehavioral phenotypes and gene expression. PLoS Genet 2008; 4:e1000260. [PMID: 19008955 PMCID: PMC2577893 DOI: 10.1371/journal.pgen.1000260] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Accepted: 10/14/2008] [Indexed: 11/18/2022] Open
Abstract
A remarkably diverse set of traits maps to a region on mouse distal chromosome 1 (Chr 1) that corresponds to human Chr 1q21-q23. This region is highly enriched in quantitative trait loci (QTLs) that control neural and behavioral phenotypes, including motor behavior, escape latency, emotionality, seizure susceptibility (Szs1), and responses to ethanol, caffeine, pentobarbital, and haloperidol. This region also controls the expression of a remarkably large number of genes, including genes that are associated with some of the classical traits that map to distal Chr 1 (e.g., seizure susceptibility). Here, we ask whether this QTL-rich region on Chr 1 (Qrr1) consists of a single master locus or a mixture of linked, but functionally unrelated, QTLs. To answer this question and to evaluate candidate genes, we generated and analyzed several gene expression, haplotype, and sequence datasets. We exploited six complementary mouse crosses, and combed through 18 expression datasets to determine class membership of genes modulated by Qrr1. Qrr1 can be broadly divided into a proximal part (Qrr1p) and a distal part (Qrr1d), each associated with the expression of distinct subsets of genes. Qrr1d controls RNA metabolism and protein synthesis, including the expression of approximately 20 aminoacyl-tRNA synthetases. Qrr1d contains a tRNA cluster, and this is a functionally pertinent candidate for the tRNA synthetases. Rgs7 and Fmn2 are other strong candidates in Qrr1d. FMN2 protein has pronounced expression in neurons, including in the dendrites, and deletion of Fmn2 had a strong effect on the expression of few genes modulated by Qrr1d. Our analysis revealed a highly complex gene expression regulatory interval in Qrr1, composed of multiple loci modulating the expression of functionally cognate sets of genes.
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Affiliation(s)
- Khyobeni Mozhui
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Daniel C. Ciobanu
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Thomas Schikorski
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Xusheng Wang
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Lu Lu
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Robert W. Williams
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- * E-mail:
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32
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Tai HC, Schuman EM. Ubiquitin, the proteasome and protein degradation in neuronal function and dysfunction. Nat Rev Neurosci 2008; 9:826-38. [PMID: 18931696 DOI: 10.1038/nrn2499] [Citation(s) in RCA: 357] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Eukaryotic protein degradation by the proteasome and the lysosome is a dynamic and complex process in which ubiquitin has a key regulatory role. The distinctive morphology of the postmitotic neuron creates unique challenges for protein degradation systems with respect to cell-surface protein turnover and substrate delivery to proteolytic machineries that are required for both synaptic plasticity and self-renewal. Moreover, the discovery of ubiquitin-positive protein aggregates in a wide spectrum of neurodegenerative diseases underlines the importance and vulnerability of the degradative system in neurons. In this article, we discuss the molecular mechanism of protein degradation in the neuron with respect to both its function and its dysfunction.
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Affiliation(s)
- Hwan-Ching Tai
- Division of Chemistry of Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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33
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Hipkiss AR. Error-protein metabolism and ageing. Biogerontology 2008; 10:523-9. [PMID: 18923917 DOI: 10.1007/s10522-008-9188-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Accepted: 04/25/2008] [Indexed: 01/19/2023]
Abstract
Ageing and many associated pathologies are accompanied by accumulation of altered proteins. It is suggested that erroneous polypeptide biosynthesis, cytosolic and mitochondrial, is not an insignificant source of aberrant protein in growing and non-mitotic cells. It is proposed that (i) synthesis of sufficient proteases and chaperone proteins necessary for rapid elimination of altered proteins, from cytoplasmic and mitochondrial compartments, is related to cellular protein biosynthetic potential, and (ii) cells growing slowly, or not at all, automatically generate lower levels of protease/chaperone molecules than cells growing rapidly, due to decreased general rate of protein synthesis and lowered amount of error-protein produced per cell. Hence the increased vulnerability of mature organisms may be explained, at least in part, by the decline in constitutive protease/chaperone protein biosynthesis. Upregulation of mitochondria biogenesis, induced by dietary restriction or aerobic exercise, may also increase protease/chaperone protein synthesis, which would improve cellular ability to degrade both error-proteins and proteins damaged post-synthetically by reactive oxygen species etc. These proposals may help explain, in part, the latency of those age-related pathologies where altered proteins accumulate only late in life, and the beneficial effects of aerobic exercise and dietary restriction.
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Affiliation(s)
- Alan R Hipkiss
- Centre for Translational Medicine and Therapeutics, William Harvey Research Institute, Bart's and the London Queen Mary's School of Medicine and Dentistry, London, UK.
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Hipkiss AR. On methionine restriction, suppression of mitochondrial dysfunction and aging. Rejuvenation Res 2008; 11:685-8. [PMID: 18593287 DOI: 10.1089/rej.2008.0701] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Rats and mice, when subjected to methionine restriction (MetR), may live longer with beneficial changes to their mitochondria. Most explanations of these observations have centered on MetR somehow suppressing the effects of oxygen free radicals. It is suggested here that MetR's effects on protein metabolism should also be considered when attempting to explain its apparent anti-aging actions. Methionine is the initiating amino acid in mRNA translation. It is proposed that MetR decreases the protein biosynthesis rate due to methionine limitation, which correspondingly decreases generation of ribosomal-mediated error proteins, which then lowers the total abnormal protein load that cellular proteases and chaperone proteins (mitochondrial and cytoplasmic) must deal with. This will increase protease availability for elimination of proteins damaged postsynthetically and help delay abnormal protein accumulation, the major molecular symptom of aging. The slowed rate of protein synthesis may also alter protein folding, which could also alter polypeptide susceptibility to oxidative attack. MetR will also increase lysosomal proteolysis, including autophagy of dysfunctional mitochondria, and promote mitogenesis. MetR may decrease synthesis of S-adenosyl-methionine (SAM), which could decrease spontaneous O(6)-methylguanine formation in DNA. However decreased SAM may compromise repair of protein isoaspartate residues by protein-isoaspartate methyltransferase (PIMT). Changes in SAM levels may also affect gene silencing. All the above may help explain, at least in part, the beneficial effects of MetR.
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Affiliation(s)
- Alan R Hipkiss
- Centre for Translational Medicine and Therapeutics, William Harvey Research Institute, Bart's and the London Queen Mary's School of Medicine and Dentistry, London, UK.
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35
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Mitochondrial medicine for aging and neurodegenerative diseases. Neuromolecular Med 2008; 10:291-315. [PMID: 18566920 DOI: 10.1007/s12017-008-8044-z] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Accepted: 05/22/2008] [Indexed: 12/22/2022]
Abstract
Mitochondria are key cytoplasmic organelles, responsible for generating cellular energy, regulating intracellular calcium levels, altering the reduction-oxidation potential of cells, and regulating cell death. Increasing evidence suggests that mitochondria play a central role in aging and in neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and Freidriech ataxia. Further, several lines of evidence suggest that mitochondrial dysfunction is an early event in most late-onset neurodegenerative diseases. Biochemical and animal model studies of inherited neurodegenerative diseases have revealed that mutant proteins of these diseases are associated with mitochondria. Mutant proteins are reported to block the transport of nuclear-encoded mitochondrial proteins to mitochondria, interact with mitochondrial proteins and disrupt the electron transport chain, induce free radicals, cause mitochondrial dysfunction, and, ultimately, damage neurons. This article discusses critical issues of mitochondria causing dysfunction in aging and neurodegenerative diseases, and discusses the potential of developing mitochondrial medicine, particularly mitochondrially targeted antioxidants, to treat aging and neurodegenerative diseases.
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36
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Sublethal RNA oxidation as a mechanism for neurodegenerative disease. Int J Mol Sci 2008; 9:789-806. [PMID: 19325784 PMCID: PMC2635712 DOI: 10.3390/ijms9050789] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 05/15/2008] [Accepted: 05/16/2008] [Indexed: 12/27/2022] Open
Abstract
Although cellular RNA is subjected to the same oxidative insults as DNA and other cellular macromolecules, oxidative damage to RNA has not been a major focus in investigations of the biological consequences of free radical damage. In fact, because it is largely single-stranded and its bases lack the protection of hydrogen bonding and binding by specific proteins, RNA may be more susceptible to oxidative insults than is DNA. Oxidative damage to protein-coding RNA or non-coding RNA will, in turn, potentially cause errors in proteins and/or dysregulation of gene expression. While less lethal than mutations in the genome, such sublethal insults to cells might be associated with underlying mechanisms of several chronic diseases, including neurodegenerative disease. Recently, oxidative RNA damage has been described in several neurodegenerative diseases including Alzheimer disease, Parkinson disease, dementia with Lewy bodies, and prion diseases. Of particular interest, oxidative RNA damage can be demonstrated in vulnerable neurons early in disease, suggesting that RNA oxidation may actively contribute to the onset of the disease. An increasing body of evidence suggests that, mechanistically speaking, the detrimental effects of oxidative RNA damage to protein synthesis are attenuated, at least in part, by the existence of protective mechanisms that prevent the incorporation of the damaged ribonucleotides into the translational machinery. Further investigations aimed at understanding the processing mechanisms related to oxidative RNA damage and its consequences may provide significant insights into the pathogenesis of neurodegenerative and other degenerative diseases and lead to better therapeutic strategies.
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37
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Li F, Zhang L, Craddock J, Bruce-Keller AJ, Dasuri K, Nguyen A, Keller JN. Aging and dietary restriction effects on ubiquitination, sumoylation, and the proteasome in the heart. Mech Ageing Dev 2008; 129:515-21. [PMID: 18533226 DOI: 10.1016/j.mad.2008.04.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 04/15/2008] [Accepted: 04/22/2008] [Indexed: 10/22/2022]
Abstract
Dietary restriction (DR), in the absence of malnutrition, is the only intervention known to reliably increase average and maximal lifespan in a variety of organisms including mammals. Because the effects of DR on the heart are poorly understood, in the present study we examined the effects of DR on the ubiquitin-proteasome pathway (UPP) in the heart. In these studies we observed that DR significantly reduced age-related impairments in proteasome-mediated protein degradation, and reduced age-related increases in ubiquitinated, oxidized, and sumoylated protein in the heart. Interestingly, DR did not significantly increase the expression of 20S proteasome subunits or the proteasome maturation factor (POMP-1). These data demonstrate for the first time the effects of aging and DR on proteasome biogenesis and sumoylation in the heart. Cumulatively, our data indicate that DR has many beneficial effects towards the UPP in the heart, and suggests that a preservation of the UPP may be a potential mechanism by which DR mediates beneficial effects on the cardiovascular system.
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Affiliation(s)
- Feng Li
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
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Finkbeiner S, Mitra S. The ubiquitin-proteasome pathway in Huntington's disease. ScientificWorldJournal 2008; 8:421-33. [PMID: 18454252 PMCID: PMC2637619 DOI: 10.1100/tsw.2008.60] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The accumulation of mutant protein is a common feature of neurodegenerative disease. In Huntington's disease, a polyglutamine expansion in the huntingtin protein triggers neuronal toxicity. Accompanying neuronal death, mutant huntingtin aggregates in large macromolecular structures called inclusion bodies. The function of the machinery for intracellular protein degradation is linked to huntingtin toxicity and components of this machinery colocalize with inclusion bodies. An increasing body of evidence implicates the ubiquitin-proteasome pathway in the failure of cells to degrade mutant huntingtin. A number of potential mechanisms that link compromised ubiquitin-proteasome pathway function and neurodegeneration have been proposed and may offer opportunities for therapeutic intervention.
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Affiliation(s)
- Steven Finkbeiner
- Gladstone Institute of Neurological Disease, 1650 Owens St., San Francisco, CA94158, USA
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39
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Torres CA, Perez VI. Proteasome modulates mitochondrial function during cellular senescence. Free Radic Biol Med 2008; 44:403-14. [PMID: 17976388 PMCID: PMC2779526 DOI: 10.1016/j.freeradbiomed.2007.10.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Revised: 09/20/2007] [Accepted: 10/01/2007] [Indexed: 01/11/2023]
Abstract
Proteasome plays fundamental roles in the removal of oxidized proteins and in the normal degradation of short-lived proteins. Previously we have provided evidence that the impairment in proteasome observed during the replicative senescence of human fibroblasts has significant effects on MAPK signaling, proliferation, life span, senescent phenotype, and protein oxidative status. These studies have demonstrated that proteasome inhibition and replicative senescence caused accumulation of intracellular protein carbonyl content. In this study, we have investigated the mechanisms by which proteasome dysfunction modulates protein oxidation during cellular senescence. The results indicate that proteasome inhibition during replicative senescence has significant effects on intra- and extracellular ROS production in vitro. The data also show that ROS impaired the proteasome function, which is partially reversible by antioxidants. Increases in ROS after proteasome inhibition correlated with a significant negative effect on the activity of most mitochondrial electron transporters. We propose that failures in proteasome during cellular senescence lead to mitochondrial dysfunction, ROS production, and oxidative stress. Furthermore, it is likely that changes in proteasome dynamics could generate a prooxidative condition at the immediate extracellular microenvironment that could cause tissue injury during aging, in vivo.
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Affiliation(s)
- Claudio A Torres
- The Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood, PA 19096, USA.
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40
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Bellavista E, Mishto M, Santoro A, Bertoni-Freddari C, Sessions RB, Franceschi C. Immunoproteasome in Macaca fascicularis: No Age-Dependent Modification of Abundance and Activity in the Brain and Insight into an in silico Structural Model. Rejuvenation Res 2008; 11:73-82. [DOI: 10.1089/rej.2007.0559] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Elena Bellavista
- Interdepartmental Center for Studies on Biophysics, Bioinformatics and Biocomplexity L. Galvani (CIG), University of Bologna, Bologna, Italy
| | - Michele Mishto
- Interdepartmental Center for Studies on Biophysics, Bioinformatics and Biocomplexity L. Galvani (CIG), University of Bologna, Bologna, Italy
| | - Aurelia Santoro
- Interdepartmental Center for Studies on Biophysics, Bioinformatics and Biocomplexity L. Galvani (CIG), University of Bologna, Bologna, Italy
| | | | - Richard B. Sessions
- Department of Biochemistry, University of Bristol, School of Medical Sciences, Bristol, United Kingdom
| | - Claudio Franceschi
- Interdepartmental Center for Studies on Biophysics, Bioinformatics and Biocomplexity L. Galvani (CIG), University of Bologna, Bologna, Italy
- Italian National Research Center for Aging, Ancona, Italy
- Department of Experimental Pathology, University of Bologna, Bologna, Italy
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41
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Yao X, Liu J, McCabe JT. Alterations of cerebral cortex and hippocampal proteasome subunit expression and function in a traumatic brain injury rat model. J Neurochem 2007; 104:353-63. [PMID: 17944870 DOI: 10.1111/j.1471-4159.2007.04970.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Following cellular stress or tissue injury, the proteasome plays a critical role in protein degradation and signal transduction. The present study examined the beta-subunit expression of constitutive proteasomes (beta1, beta2, and beta5), immunoproteasomes (beta1i, beta2i, and beta5i) and the 11S proteasome activator, PA28alpha, in the rat CNS after traumatic brain injury (TBI). Concomitant measures assessed changes in proteasome activities. Quantitative real time PCR results indicated that beta1 and beta2 mRNA levels were not changed, while beta5 mRNA levels were significantly decreased in injured CNS following TBI. However, beta1i, beta2i, beta5i, and PA28alpha mRNA levels were significantly increased in the injured CNS. Western blotting studies found that beta1, beta2, beta5, beta2i, and beta5i subunit protein levels remained unchanged in the injured CNS, but beta1i and PA28alpha protein levels were significantly elevated in ipsilateral cerebral cortex and hippocampus. Proteasome activity assays found that peptidyl glutamyl peptide hydrolase-like and chymotrypsin-like activity were significantly reduced in the CNS after TBI, and that trypsin-like proteasome activity was increased in the injured cerebral cortex. Our results demonstrated that both proteasome composition and function in the CNS were affected by trauma. Treatments that preserve proteasome function following CNS injury may be beneficial as an approach to cerebral neuroprotection.
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Affiliation(s)
- Xianglan Yao
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799, USA.
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Ding Q, Dimayuga E, Keller JN. Oxidative stress alters neuronal RNA- and protein-synthesis: Implications for neural viability. Free Radic Res 2007; 41:903-10. [PMID: 17654047 DOI: 10.1080/10715760701416996] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Recent studies have demonstrated that impaired protein synthesis occurs in several neurodegenerative conditions associated with oxidative stress. Studies have also demonstrated that administration of oxidative stressors is sufficient to impair different and discrete regulatory aspects of protein synthesis in neural cells, with the majority of these studies focused on the effects of oxidative stressors towards initiation factors. Currently, little is known with regards to oxidative stress effects on the rates of RNA- and protein-synthesis, or the relationship between oxidant-induced impairments in RNA-/protein-synthesis to subsequent neuron death. In the present study, we demonstrate that administration of an oxidative stressor (hydrogen peroxide) induces a significant and time-dependent decrease in both RNA- and protein-synthesis in primary neurons and neural SH-SY5Y cells. Increases in RNA oxidation and disruption of ribosome complexes were selectively observed following the longer durations of oxidant exposure. Significant correlations between the loss of RNA- and protein-synthesis and the amount of oxidant-induced neuron death were also observed. Interestingly, the addition of a protein synthesis inhibitor (cycloheximide) did not significantly alter the amount of neuron death induced by the oxidative stressor. These data demonstrate that oxidant exposure promotes a time-dependent decrease in both RNA- and protein-synthesis in neurons, and demonstrate a role for elevations in RNA oxidation and ribosome dysfunction as potential mediators of impaired protein synthesis. These data also suggest that there is a complex relationship between the ability of oxidative stressors to modulate RNA- and protein-synthesis, and the ability of oxidative stressors to ultimately induce neuron death.
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Affiliation(s)
- Qunxing Ding
- Anatomy and Neurobiology, University of Kentucky, Lexington, KY 40536-0230, USA
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Abstract
In the present study we isolated proteasome complexes from control, mild cognitive impairment (MCI), and Alzheimer's disease (AD) subjects. No significant difference in the amount of proteasomes was detected across the different groups, although impairments in chymotrypsin-like proteasome activity was observed in AD subjects. Large impairments in proteasome- mediated degradation of an oxidized protein substrate was observed in MCI and AD subjects. Incubation with a reducing agent (DTT) had no significant effect on proteasome chymotrypsin-like activity, but fully restored proteasome-mediated protein degradation in MCI and AD subjects. Proteasomes from AD subjects exhibited elevations in protein carbonyls, 4-hydroxynonenal-conjugation, and neuroprostane-conjugation. Together, these data confirm that impairments in the function of purified proteasomes occurs in the earliest stages of AD, and directly support a role for oxidative inactivation contributing to declines in proteasome function in AD.
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Affiliation(s)
- Valentina Cecarini
- Sanders Brown Center on Aging, University of Kentucky, Lexington, KY 40536-0230, USA
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