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Shah MA, Kang JB, Koh PO. Chlorogenic acid modulates the ubiquitin-proteasome system in stroke animal model. Lab Anim Res 2022; 38:41. [PMID: 36539905 PMCID: PMC9768937 DOI: 10.1186/s42826-022-00151-2] [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: 08/21/2022] [Revised: 12/05/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Chlorogenic acid, a phenolic compound, has potent antioxidant and neuroprotective properties. The ubiquitin-proteasome system is an important regulators of neurodevelopment and modulators of neuronal function. This system is associated with neurodevelopment and neurotransmission through degradation and removal of damaged proteins. Activation of the ubiquitin-proteasome system is a critical factor in preventing cell death. We have previously reported a decrease in the activity of the ubiquitin-proteasome system during cerebral ischemia. This study investigated whether chlorogenic acid regulates the ubiquitin-proteasome system in an animal stroke model. In adult rats, middle cerebral artery occlusion (MCAO) surgery was performed to induce focal cerebral ischemia. Chlorogenic acid (30 mg/kg) or normal saline was injected into the abdominal cavity 2 h after MCAO surgery, and cerebral cortex tissues were collected 24 h after MCAO damage. RESULTS Chlorogenic acid attenuated neurobehavioral disorders and histopathological changes caused by MCAO damage. We identified the decreases in ubiquitin C-terminal hydrolase L1, ubiquitin thioesterase OTUB1, proteasome subunit α type 1, proteasome subunit α type 3, and proteasome subunit β type 4 expression using a proteomics approach in MCAO animals. The decrease in these proteins was alleviated by chlorogenic acid. In addition, the results of reverse transcription-polymerase chain reaction confirmed these changes. The identified proteins were markedly reduced in MCAO damage, while chlorogenic acid prevented these reductions induced by MCAO. The decrease of ubiquitin-proteasome system proteins in ischemic damage was associated with neuronal apoptosis. CONCLUSIONS Our results showed that chlorogenic acid regulates ubiquitin-proteasome system proteins and protects cortical neurons from neuronal damage. These results provide evidence that chlorogenic acid has neuroprotective effects and maintains the ubiquitin-proteasome system in ischemic brain injury.
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Affiliation(s)
- Murad-Ali Shah
- grid.256681.e0000 0001 0661 1492Department of Anatomy, College of Veterinary Medicine, Research Institute of Life Science, Gyeongsang National University, 501 Jinju-Daero, Jinju, 52828 South Korea
| | - Ju-Bin Kang
- grid.256681.e0000 0001 0661 1492Department of Anatomy, College of Veterinary Medicine, Research Institute of Life Science, Gyeongsang National University, 501 Jinju-Daero, Jinju, 52828 South Korea
| | - Phil-Ok Koh
- grid.256681.e0000 0001 0661 1492Department of Anatomy, College of Veterinary Medicine, Research Institute of Life Science, Gyeongsang National University, 501 Jinju-Daero, Jinju, 52828 South Korea
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2
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Proteasome inhibition by MG-132 protects against deltamethrin-induced apoptosis in rat hippocampus. Life Sci 2019; 220:76-83. [PMID: 30695709 DOI: 10.1016/j.lfs.2019.01.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 01/06/2019] [Accepted: 01/25/2019] [Indexed: 11/21/2022]
Abstract
AIMS Deltamethrin (DM), a type II synthetic pyrethroid insecticide, is widely used in agriculture and home pest control. The evaluation of their toxic effects is of major concern to public health. However, the molecular mechanism of DM-induced neurodegenerative disease is still far from clear. This study was designed to investigate the potential role of ubiquitin proteasome system (UPS) in DM-induced neurotoxicity where the proteasome inhibitor MG-132 could mitigate the neurotoxic effects. MAIN METHODS Male Sprague-Dawley rats were divided into two batches. The first batch of rats was administrated with a single dose of DM (12.5 mg/kg) by intraperitoneal injections (i.p.) and the animals were then euthanized at 5, 24, and 48 h post injection. The second batch was treated as follow: control group, DM (12.5 mg/kg) groups for 24 h, MG-132 (0.5 mg/kg, i.p.) 2 h plus DM 24 h group, and MG-132 alone group. Ubiqutinatied proteins, DNA damage and apoptosis were investigated. KEY FINDINGS DM treatment induced the ubiquitinated proteins expression with the peaks at 5 h. Moreover, DM increased DNA damage, early apoptotic rate, the expression level of Cleaved Caspase-3, caspase-3 activity and decreased the expression level of Bcl-2 at DM 24 h group. Compared to DM 24 h group, MG-132 pretreatment significantly down-regulated ubiquitinated proteins, lowered the DNA damage and apoptosis by decreasing Caspase-3 and increasing Bcl-2 expression. SIGNIFICANCE These results indicate that MG-132 effectively alleviates DM-induced DNA damage and apoptosis by inhibiting ubiquitinated proteins. UPS may play a role in DM-induced neurodegenerative disorders.
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Fedoce ADG, Ferreira F, Bota RG, Bonet-Costa V, Sun PY, Davies KJA. The role of oxidative stress in anxiety disorder: cause or consequence? Free Radic Res 2018; 52:737-750. [PMID: 29742940 PMCID: PMC6218334 DOI: 10.1080/10715762.2018.1475733] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Anxiety disorders are the most common mental illness in the USA affecting 18% of the population. The cause(s) of anxiety disorders is/are not completely clear, and research in the neurobiology of anxiety at the molecular level is still rather limited. Although mounting clinical and preclinical evidence now indicates that oxidative stress may be a major component of anxiety pathology, whether oxidative stress is the cause or consequence remains elusive. Studies conducted over the past few years suggest that anxiety disorders may be characterised by lowered antioxidant defences and increased oxidative damage to proteins, lipids, and nucleic acids. In particular, oxidative modifications to proteins have actually been proposed as a potential factor in the onset and progression of several psychiatric disorders, including anxiety and depressive disorders. Oxidised proteins are normally degraded by the proteasome proteolytic complex in the cell cytoplasm, nucleus, and endoplasmic reticulum. The Lon protease performs a similar protective function inside mitochondria. Impairment of the proteasome and/or the Lon protease results in the accumulation of toxic oxidised proteins in the brain, which can cause severe neuronal trauma. Recent evidence points to possible proteolytic dysfunction and accumulation of damaged, oxidised proteins as factors that may determine the appearance and severity of psychotic symptoms in mood disorders. Thus, critical interactions between oxidative stress, proteasome, and the Lon protease may provide keys to the molecular mechanisms involved in emotional regulation, and may also be of great help in designing and screening novel anxiolytics and antidepressants.
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Affiliation(s)
- Alessandra das Graças Fedoce
- Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center, The University of Southern California, Los Angeles, CA 90089-0191, USA
| | - Frederico Ferreira
- Oswaldo Cruz Foundation, Oswaldo Cruz Institute, Laboratory on Thymus Research, Rio de Janeiro, Brazil
| | - Robert G. Bota
- Department of Psychiatry, University of California, Irvine, Orange, CA 92868
| | - Vicent Bonet-Costa
- Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center, The University of Southern California, Los Angeles, CA 90089-0191, USA
| | - Patrick Y. Sun
- Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center, The University of Southern California, Los Angeles, CA 90089-0191, USA
| | - Kelvin J. A. Davies
- Leonard Davis School of Gerontology of the Ethel Percy Andrus Gerontology Center, The University of Southern California, Los Angeles, CA 90089-0191, USA
- Division of Molecular & Computational Biology, Department of Biological Sciences, Dornsife College of Letters, Arts, & Sciences, The University of Southern California, Los Angeles, CA 90089-0191, USA
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4
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Zhou W, Wei L, Xiao T, Lai C, Peng M, Xu L, Luo X, Deng S, Zhang F. Diabetogenic agent alloxan is a proteasome inhibitor. Biochem Biophys Res Commun 2017; 488:400-406. [PMID: 28502636 DOI: 10.1016/j.bbrc.2017.05.065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 05/10/2017] [Indexed: 11/19/2022]
Abstract
Alloxan has been used as a diabetogenic agent to induce diabetes. It selectively induces pancreatic β-cell death. The specific toxicity, however, is not fully understood. In this study, we observed the effect of alloxan on proteasome function. We found that alloxan caused the accumulation of ubiquitinated proteins in NRK cells through the inhibition of the proteolytic activities of the proteasome. Biochemistry experiments with purified 26S and 20S proteasomes revealed that alloxan directly acts on the chymotrypsin- and trypsin-like peptidase activities. These results demonstrate that alloxan is a proteasome inhibitor, which suggests that its specific toxicity toward β-cell is at least in part through proteasome inhibition.
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Affiliation(s)
- Wenjuan Zhou
- Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, SC 610072, China
| | - Lingling Wei
- Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, SC 610072, China
| | - Ting Xiao
- Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, SC 610072, China
| | - Chunyou Lai
- Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, SC 610072, China
| | - Min Peng
- Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, SC 610072, China
| | - Lingli Xu
- Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, SC 610072, China
| | - Xiangwei Luo
- Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, SC 610072, China
| | - Shaoping Deng
- Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, SC 610072, China
| | - Fengxue Zhang
- Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, SC 610072, China.
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Tanigawa M, Suzuki C, Niwano K, Kanekatsu R, Tanaka H, Horiike K, Hamase K, Nagata Y. Participation of D-serine in the development and reproduction of the silkworm Bombyx mori. JOURNAL OF INSECT PHYSIOLOGY 2016; 87:20-29. [PMID: 26828952 DOI: 10.1016/j.jinsphys.2016.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 01/27/2016] [Accepted: 01/29/2016] [Indexed: 06/05/2023]
Abstract
The silkworm Bombyx mori contains high concentrations of free D-serine, an optical isomer of L-serine. To elucidate its function, we first investigated the localization of D-serine in various organs of silkworm larvae, pupae, and adult moths. Using immunohistochemical analysis with an anti-D-serine antibody, we found D-serine in the microvilli of midgut goblet and cylindrical cells and in peripheral matrix components of testicular and ovarian cells. By spectrophotometric analysis, D-serine was also found in the hemolymph and fat body. D-Alanine was not detected in the various organs by immunohistochemistry. Serine racemase, which catalyzes the inter-conversion of L- and D-serine, was found to co-localize with D-serine, and D-serine production from L-serine by intrinsic serine racemase was suggested. O-Phospho-L-serine is an inhibitor of serine racemase, and it was administered to the larvae to reduce the D-serine level. This reagent decreased the midgut caspase-3 level and caused a delay in spermatogenesis and oogenesis. The reagent also decreased mature sperm and egg numbers, suggesting D-serine participation in these processes. D-Serine administration induced an increase in pyruvate levels in testis, midgut, and fat body, indicating conversion of D-serine to pyruvate. On the basis of these results, together with our previous investigation of ATP biosynthesis in testis, we consider the possible involvement of D-serine in ATP synthesis for metamorphosis and reproduction.
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Affiliation(s)
- Minoru Tanigawa
- Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, Chiyoda-Ward, Tokyo 101-8308, Japan
| | - Chihiro Suzuki
- Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, Chiyoda-Ward, Tokyo 101-8308, Japan
| | - Kimio Niwano
- Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, Chiyoda-Ward, Tokyo 101-8308, Japan
| | - Rensuke Kanekatsu
- Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan
| | - Hiroyuki Tanaka
- Department of Biochemistry and Molecular Biology, Shiga University of Medical Science, Seta, Shiga 520-2192, Japan
| | - Kihachiro Horiike
- Department of Biochemistry and Molecular Biology, Shiga University of Medical Science, Seta, Shiga 520-2192, Japan
| | - Kenji Hamase
- Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan
| | - Yoko Nagata
- Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, Chiyoda-Ward, Tokyo 101-8308, Japan.
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Oxidative Stress and Proteostasis Network: Culprit and Casualty of Alzheimer’s-Like Neurodegeneration. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/527518] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Free radical-mediated damage to proteins is particularly important in aging and age-related neurodegenerative diseases, because in the majority of cases it is a non-reversible phenomenon that requires clearance systems for removal. Major consequences of protein oxidation are loss of protein function and the formation of large protein aggregates, which are often toxic to cells if allowed to accumulate. Deposition of aggregated, misfolded, and oxidized proteins may also result from the impairment of protein quality control (PQC) system, including protein unfolded response, proteasome, and autophagy. Perturbations of such components of the proteostasis network that provides a critical protective role against stress conditions are emerging as relevant factor in triggering neuronal death. In this outlook paper, we discuss the role of protein oxidation as a major contributing factor for the impairment of the PQC regulating protein folding, surveillance, and degradation. Recent studies from our group and from others aim to better understand the link between Down syndrome and Alzheimer’s disease neuropathology. We propose oxidative stress and alteration of proteostasis network as a possible unifying mechanism triggering neurodegeneration.
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Peña-Altamira E, Polazzi E, Moretto E, Lauriola M, Monti B. The transcription factor CCAAT enhancer-binding protein β protects rat cerebellar granule neurons from apoptosis through its transcription-activating isoforms. Eur J Neurosci 2013; 39:176-85. [PMID: 24438488 DOI: 10.1111/ejn.12407] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 10/02/2013] [Accepted: 10/04/2013] [Indexed: 01/07/2023]
Abstract
CCAAT enhancer-binding protein β is a transcription factor that is involved in many brain processes, although its role in neuronal survival/death remains unclear. By using primary cultures of rat cerebellar granule neurons, we have shown here that CCAAT enhancer-binding protein β is present as all of its isoforms: the transcriptional activators liver activator proteins 1 and 2, and the transcriptional inhibitor liver inhibitory protein. We have also shown that liver activator protein 1 undergoes post-translational modifications, such as phosphorylation and sumoylation. These isoforms have different subcellular localizations, liver activator protein 2 being found in the cytosolic fraction only, liver inhibitory protein in the nucleus only, and liver activator protein 1 in both fractions. Through neuronal apoptosis induction by shifting mature cerebellar granule neurons to low-potassium medium, we have demonstrated that nuclear liver activator protein 1 expression decreases and its phosphorylation disappears, whereas liver inhibitory protein levels increase in the nuclear fraction, suggesting a pro-survival role for liver activator protein transcriptional activation and a pro-apoptotic role for liver inhibitory protein transcriptional inhibition. To confirm this, we transfected cerebellar granule neurons with plasmids expressing liver activator protein 1, liver activator protein 2, or liver inhibitory protein respectively, and observed that both liver activator proteins, which increase CCAAT-dependent transcription, but not liver inhibitory protein, counteracted apoptosis, thus demonstrating the pro-survival role of liver activator proteins. These data significantly improve our current understanding of the role of CCAAT enhancer-binding protein β in neuronal survival/apoptosis.
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Affiliation(s)
- Emiliano Peña-Altamira
- Department of Pharmacy and BioTechnology, University of Bologna, Ex-BES Building, Via Selmi 3, Bologna, 40126, Italy
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8
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Ying Z, Li A, Lu Z, Wu C, Yin H, Yuan M, Pang Y. The Spodoptera frugiperda effector caspase Sf-caspase-1 becomes unstable following its activation. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2013; 83:195-210. [PMID: 23740663 DOI: 10.1002/arch.21106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Sf-caspase-1 is the principal effector caspase in Spodoptera frugiperda cells. Like the caspases in other organisms, Sf-caspase-1 is processed by upstream caspases to form an active heterotetramer composed of the p19 and p12 subunits. The regulation of active caspases is crucial for cellular viability. In mammal cells, the subunits and the active form of caspase-3 were rapidly degraded relative to its proenzyme form. In the present study, the S. frugiperda Sf9 cells were transiently transfected with plasmids encoding different fragments of Sf-caspase-1: the pro-Sf-caspase-1 (p37), a prodomain deleted fragment (p31), a fragment containing the large subunit and the prodomain (p25), the large subunit (p19), and the small subunit (p12). Flow cytometry and Western blot analysis revealed that p12, p19, and p25 were unstable in the transfected cells, in contrast to p37 and p31. Lactacystin, a proteasome inhibitor, increased the accumulation of the p19 and p12 subunits, suggesting that the degradation is performed by the ubiquitin-proteasome system. During the activation, the Sf-caspase-1 produces an intermediate form and then undergoes proteolytic processing to form active Sf-caspase-1. We found that both the active and the intermediate form were unstable, indicating that once activated or during its activation, the Sf-caspase-1 was unstable.
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Affiliation(s)
- Zhongfu Ying
- State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, PR China
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9
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Prudnikov IM, Smirnov AN. Short peptide tools for monitoring caspase and proteasome activities in embryonal and adult rat brain lysates: an approach for the differential identification of proteases. J Biochem 2012; 151:299-316. [PMID: 22228904 DOI: 10.1093/jb/mvs001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The numerous caspase-like activities present in nervous tissue can be investigated with labelled peptides. However, the cross-reactivities of peptides with both proteasomes and caspases complicate the analysis of protease activity. The pharmacological features of substrates and inhibitors specific for either caspases or proteasome caspase-like proteases in rat brain lysates were similar or identical to the profiles of commercially purified proteasome preparations. Caspase inhibitors bind directly to active proteasome centres, thus competing with selective antagonists of proteasomes. Separation of lysates by molecular weight does not separate active caspases from proteasomes because these enzymes co-localize under native electrophoresis. The addition of ATP or its analogues is associated with the differential modulation of proteasomal activity, which also leads to ambiguity in the data. However, induced caspase activity could be successfully differentiated from proteasome activity in embryonal brain lysates with the non-selective caspase inhibitors Z-VAD-FMK and Q-VD-OPh and the proteasome inhibitor AdaAhx(3)L(3)VS that are not cross-reactive. This strategy is proposed for the simultaneous examination of caspases and proteasomes using proteolysis experiments. The present study reveals that all of the caspase-like activities in the tissue lysates of non-injured adult rat brains were related to proteasomal caspase-like activities.
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Affiliation(s)
- Igor M Prudnikov
- Laboratory of stem cell biology, A. Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Bogomoletz str., 4, 01024, Kiev, Ukraine.
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10
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Droggiti A, Ho CCY, Stefanis L, Dauer WT, Rideout HJ. Targeted disruption of neuronal 19S proteasome subunits induces the formation of ubiquitinated inclusions in the absence of cell death. J Neurochem 2011; 119:630-43. [PMID: 21883213 DOI: 10.1111/j.1471-4159.2011.07444.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Proteasome-mediated proteolysis is a major protein degradation mechanism in cells and its dysfunction has been implicated in the pathogenesis of several neurodegenerative diseases, each with the common features of neuronal death and formation of ubiquitinated inclusions found within neurites, the cell body, or nucleus. Previous models of proteasome dysfunction have employed pharmacological inhibition of the catalytic subunits of the 20S proteasome core, or the genetic manipulation of specific subunits resulting in altered proteasome assembly. In this study, we report the use of dominant negative subunits of the 19S regulatory proteasome complex that mediate the recognition of ubiquitinated substrates as well as the removal of the poly-ubiquitin chain. Interestingly, while each mutant subunit-induced inclusion formation, like that seen with pharmacological inhibition of the 20S proteasome, none was able to induce apoptotic death, or trigger activation of macroautophagy, in either dopaminergic cell lines or primary cortical neurons. This finding highlights the dissociation between the mechanisms of neuronal inclusion formation and the induction of cell death, and represents a novel cellular model for Lewy body-like inclusion formation in neurons.
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Affiliation(s)
- Anna Droggiti
- Biomedical Research Foundation of the Academy of Athens, Division of Basic Neurosciences, Athens, Greece
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Insulin-like growth factor-I mediates neuroprotection in proteasome inhibition-induced cytotoxicity in SH-SY5Y cells. Mol Cell Neurosci 2011; 47:181-90. [PMID: 21545837 DOI: 10.1016/j.mcn.2011.04.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 03/21/2011] [Accepted: 04/12/2011] [Indexed: 12/28/2022] Open
Abstract
The proteasome is an enzyme complex responsible for targeted intracellular proteolysis. Alterations in proteasome-mediated protein clearance have been implicated in the pathogenesis of aging, Alzheimer's disease (AD) and Parkinson's disease (PD). In such diseases, proteasome inhibition may contribute to formation of abnormal protein aggregates, which in turn activate intracellular unfolded protein responses that cause oxidative stress and apoptosis. In this study, we investigated the protective effect of Insulin-like Growth Factor-I (IGF-1) for neural SH-SY5Y cells treated with the proteasomal inhibitor, Epoxomicin. In SH-SY5Y cells, Epoxomicin treatment results in accumulation of intracellular ubiquitinated proteins and cytochrome c release from damaged mitochondria, leading to cell death, in Epoxomicin time- and dose-dependent manner. In cells treated with small amounts of IGF-1, the same dosages of Epoxomicin reduced both mitochondrial damage (cytochrome c release) and reduced caspase-3 activation and PARP cleavage, both of which are markers of apoptosis. Notably, however, IGF-1-treated SH-SY5Y cells still contained ubiquitinated protein aggregates. This result indicates that IGF-1 blocks the downstream apoptotic consequences of Epoxomicin treatment leading to decreased proteasome function. Clues as to the mechanism for this protective effect come from (a) increased AKT phosphorylation observed in IGF-1-protected cells, vs. cells exposed to Epoxomicin without IGF-1, and (b) reduction of IGF-1 protection by pretreatment of the cells with LY294002 (an inhibitor of PI3-kinase). Together these findings suggest that activation of PI3/AKT pathways by IGF-1 is involved in IGF-1 neuroprotection against apoptosis following proteasome inhibition.
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Chew J, Chen MJ, Lee AYW, Peng ZF, Chong KWY, He L, Bay BH, Ng JMJ, Qi RZ, Cheung NS. Identification of p10 as a neurotoxic product generated from the proteolytic cleavage of the neuronal Cdk5 activator. J Cell Biochem 2011; 111:1359-66. [PMID: 20830735 DOI: 10.1002/jcb.22864] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The involvement of cyclin-dependent kinase-5 (Cdk5) and p25, the proteolytic fragment of activator p35, has long been implicated in the development of neuron-fibrillary tangles (NFTs), a hallmark of Alzheimer's disease (AD). Findings in this area over the past decade have been highly controversial and inconclusive. Here we report unprecedented detection of endogenous p10, the smaller proteolytic fragment of the Cdk5 activator p35 in treated primary cortical neurons that underwent significant apoptosis, triggered by proteasome inhibitors MG132 and lactacystin, and protein kinase inhibitor staurosporine (STS). p10 appeared exclusively in the detergent-resistant fraction made up of nuclear matrix, membrane-bound organelles, insoluble membrane proteins, and cytoskeletal components. Intriguingly, transient overexpression of p10 in neural cells induced apoptotic morphologies, suggesting that p10 may play an important role in mediating neuronal cell death in neurodegenerative diseases. We demonstrated for the first time that p10-mediated apoptosis occurred via a caspases-independent pathway. Furthermore, as p10 may contain the myristoylation signal for p35 which is responsible for binding p35 to several intracellular components and the membrane, all in all these novel results present that the accumulation of p10 to the detergent-insoluble fraction may be a crucial pathological event to triggering neuronal cell death.
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Affiliation(s)
- Jenny Chew
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore 117597, Singapore
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van Tijn P, Verhage MC, Hobo B, van Leeuwen FW, Fischer DF. Low levels of mutant ubiquitin are degraded by the proteasome in vivo. J Neurosci Res 2010; 88:2325-37. [PMID: 20336771 DOI: 10.1002/jnr.22396] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The ubiquitin-proteasome system fulfills a pivotal role in regulating intracellular protein turnover. Impairment of this system is implicated in the pathogenesis of neurodegenerative diseases characterized by ubiquitin- containing proteinaceous deposits. UBB(+1), a mutant ubiquitin, is one of the proteins accumulating in the neuropathological hallmarks of tauopathies, including Alzheimer's disease, and polyglutamine diseases. In vitro, UBB(+1) properties shift from a proteasomal ubiquitin-fusion degradation substrate at low expression levels to a proteasome inhibitor at high expression levels. Here we report on a novel transgenic mouse line (line 6663) expressing low levels of neuronal UBB(+1). In these mice, UBB(+1) protein is scarcely detectable in the neuronal cell population. Accumulation of UBB(+1) commences only after intracranial infusion of the proteasome inhibitors lactacystin or MG262, showing that, at these low expression levels, the UBB(+1) protein is a substrate for proteasomal degradation in vivo. In addition, accumulation of the protein serves as a reporter for proteasome inhibition. These findings strengthen our proposition that, in healthy brain, UBB(+1) is continuously degraded and disease-related UBB(+1) accumulation serves as an endogenous marker for proteasomal dysfunction. This novel transgenic line can give more insight into the intrinsic properties of UBB(+1) and its role in neurodegenerative disease.
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Affiliation(s)
- Paula van Tijn
- Netherlands Institute for Neuroscience, an institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
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14
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Chong KWY, Chen MJ, Koay ESC, Wong BS, Lee AYW, Russo-Marie F, Cheung NS. Annexin A3 is associated with cell death in lactacystin-mediated neuronal injury. Neurosci Lett 2010; 485:129-33. [PMID: 20831894 DOI: 10.1016/j.neulet.2010.08.089] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 07/28/2010] [Accepted: 08/31/2010] [Indexed: 11/17/2022]
Abstract
Massive neuronal apoptosis and accumulation of protein aggregates in the cortex and hippocampus of the brain are hallmarks of several neurodegenerative disorders, indicating ubiquitin proteasome system (UPS) dysfunction. Lactacystin, a classical proteasome inhibitor, is used to simulate ubiquitin proteasome system dysfunction in neurons to mimic pathological features of neurodegenerative disorders. Based on Western blot analyses, we reported for the first time that annexin A3 (AnxA3) is not only endogenously expressed in mouse cortical neurons but also more importantly, by gene expression microarray and real-time RT-PCR that it is greatly transcriptional up-regulated to approximately 11- and 15-fold, respectively in murine primary cortical neurons with 1μM lactacystin for 24h. Up-regulation of AnxA3 expression occurred after 12-15h post-lactacystin treatment, which corresponded with the onset of neuronal injury, with approximately 25% of the neurons being non-viable by that time interval. Western blot analysis with anti-AnxA3 antibodies further validated that up-regulation of AnxA3 only occurs with onset of neuronal death, and not with the onset of proteasome inhibition, which occurs at 4.5h post-lactacystin treatment. Over-expression studies suggested AnxA3 might be involved in death promotion during lactacystin-mediated neuronal death, since caspase-3 activation was significantly stronger upon neuronal AnxA3 over-expression. We propose AnxA3 up-regulation may have significant relevance in the elucidation of neurodegenerative pathophysiology.
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Affiliation(s)
- Kevin Wai Yin Chong
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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15
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Donev R, Kolev M, Millet B, Thome J. Neuronal death in Alzheimer's disease and therapeutic opportunities. J Cell Mol Med 2009; 13:4329-48. [PMID: 19725918 PMCID: PMC4515050 DOI: 10.1111/j.1582-4934.2009.00889.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Alzheimer’s disease (AD) is an age-related neurodegenerative disease that affects approximately 24 million people worldwide. A number of different risk factors have been implicated in AD; however, neuritic (amyloid) plaques are considered as one of the defining risk factors and pathological hallmarks of the disease. In the past decade, enormous efforts have been devoted to understand the genetics and molecular pathogenesis leading to neuronal death in AD, which has been transferred into extensive experimental approaches aimed at reversing disease progression. Modern medicine is facing an increasing number of treatments available for vascular and neurodegenerative brain diseases, but no causal or neuroprotective treatment has yet been established. Almost all neurological conditions are characterized by progressive neuronal dysfunction, which, regardless of the pathogenetic mechanism, finally leads to neuronal death. The particular emphasis of this review is on risk factors and mechanisms resulting in neuronal loss in AD and current and prospective opportunities for therapeutic interventions. This review discusses these issues with a view to inspiring the development of new agents that could be useful for the treatment of AD.
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Affiliation(s)
- Rossen Donev
- Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Heath Park, Cardiff, UK
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16
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Millet V, Moiola CP, Pasquini JM, Soto EF, Pasquini LA. Partial inhibition of proteasome activity enhances remyelination after cuprizone-induced demyelination. Exp Neurol 2009; 217:282-96. [PMID: 19303006 DOI: 10.1016/j.expneurol.2009.03.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2008] [Revised: 02/12/2009] [Accepted: 03/03/2009] [Indexed: 01/01/2023]
Abstract
We have previously demonstrated that addition of low concentrations of lactacystin (a specific inhibitor of the proteasome) to oligodendroglial cell cultures containing a high percentage of precursor cells induces their exit from the cell cycle and their differentiation. On the other hand, we have recently shown that the mechanism of cuprizone toxicity on oligodendroglial cells involves the recruitment of microglia and their secretion of pro-inflammatory cytokines and in the increased production of oxidant species, which results in a decrease in the activities of the mitochondrial respiratory chain. In the present paper we investigated the effect of a decrease in proteasome activity induced by the injection of lactacystin in the corpus callosum in the remyelination process that normally occurs after cuprizone-induced demyelination. This treatment markedly improves the remyelination process that normally occurs in cuprizone-induced demyelination. It also attenuates the activation of NFkappaB and the recruitment of microglia and astrocytes, thus helping in the recovery of the mitochondrial respiratory chain activities that are affected by cuprizone treatment.
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Affiliation(s)
- V Millet
- Departamento de Química Biológica - Instituto de Química y Fisicoquímica Biológica, Facultad de Farmacia y Bioquímica - Universidad de Buenos Aires-CONICET Junin 956 - Buenos Aires 1113 - Argentina
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17
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Yu WR, Liu T, Fehlings TK, Fehlings MG. Involvement of mitochondrial signaling pathways in the mechanism of Fas-mediated apoptosis after spinal cord injury. Eur J Neurosci 2009; 29:114-31. [DOI: 10.1111/j.1460-9568.2008.06555.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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18
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Phosphorylation of eIF2alpha in response to 26S proteasome inhibition is mediated by the haem-regulated inhibitor (HRI) kinase. Biochem J 2008; 412:579-88. [PMID: 18290760 DOI: 10.1042/bj20080324] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The present study demonstrates that even brief inhibition of degradation by the 26S proteasome inhibits global protein synthesis, mediated through increased phosphorylation of eIF2alpha (eukaryotic translational initiation factor 2alpha) by the HRI (haem-regulated inhibitor) kinase. Exposure of COS-7 cells to the proteasome inhibitor MG-132 (the proteasome inhibitor carbobenzoxy-L-leucyl-L-leucyl-leucinal) for 4 h resulted in a 55-60% decrease in protein synthesis rate compared with control cells. This repression of protein synthesis after treatment with MG-132 is not due to induction of apoptosis, which is known to occur after longer periods of 26S inhibition. Instead, we observed a significantly increased phosphorylation of eIF2alpha, which is known to repress global protein synthesis. In three MEF (mouse embryonic fibroblast) knockout cell lines lacking one of the four kinases known to phosphorylate eIF2alpha, increased phosphorylation of eIF2alpha still occurred after inhibition of the 26S proteasome. These three cell lines included a deletion of the PKR (double-stranded-RNA-dependent protein kinase); a deletion of the PERK (PKR-like endoplasmic reticulum resident kinase); or a deletion of the GCN2 (positive general control of transcription-2) kinase, indicating that none of these kinases was primarily responsible for the observed phosphorylation of eIF2alpha. In contrast, in a fourth MEF knockout cell line, HRI(-/-) cells lacking the HRI kinase failed to increase eIF2alpha phosphorylation upon proteasome inhibitor treatment (MG-132 or various doses of Bortezomib), indicating that the HRI kinase is the primary kinase activated by brief treatment of MEFs with 26S proteasome inhibitors.
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19
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Zhang F, Paterson AJ, Huang P, Wang K, Kudlow JE. Metabolic control of proteasome function. Physiology (Bethesda) 2008; 22:373-9. [PMID: 18073410 DOI: 10.1152/physiol.00026.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Proteasomes are major cellular proteases that are important for protein turnover and cell survival. Dysregulation of proteasome is related to many major human diseases. Regulation of the proteasome is beginning to be understood by the recent findings that proteasomes are modified and regulated by metabolic factors O-GlcNAcylation and PKA phosphorylation.
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Affiliation(s)
- Fengxue Zhang
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Alabama at Birmingham, USA
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20
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Bazzini E, Samuele A, Granelli M, Levandis G, Armentero MT, Nappi G, Blandini F. Proteasomal inhibition and apoptosis regulatory changes in human isolated lymphocytes: The synergistic role of dopamine. J Cell Biochem 2008; 103:877-85. [PMID: 17647258 DOI: 10.1002/jcb.21457] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Abnormal deposition of protein aggregates and increased susceptibility to apoptotic cell death may result from defects in the activity of the ubiquitin-proteasome system (UPS); neurotoxicity related to UPS defects seems to require dopamine to be fully expressed. The aim of this study was to investigate the pro-apoptotic effects caused by proteasomal activity inhibition, as well as the synergistic effect of dopaminergic stimulation in human lymphocytes isolated from healthy volunteers. Cells were incubated 20 h at 37 degrees C, with: (1) lactacystin, (2) increasing concentrations of dopamine or (3) mixture of dopamine and lactacystin. Activities of proteasome 20S and pro-apoptotic caspases-3 and -9 and levels of anti-apoptotic Bcl-2 were measured with fluorimetric or immunochemical assays, while a "DNA diffusion" assay was used to determine the apoptosis. Incubation of lymphocytes with lactacystin, which caused reduction of proteasomal activity, was associated with activation of caspases. A clear, dose-dependent reduction of proteasomal activity was also seen in the presence of increasing doses of dopamine, which was accompanied by a slight dose-dependent increase of caspases activities and Bcl-2 levels. Both effects on proteasome and caspase activities were enhanced when cells were simultaneously exposed to lactacystin and elevated concentrations of dopamine. Apoptosis was detected in all treated samples, but not in controls, without significant differences among the treatment groups; however, the association of dopamine and lactacystin induced a clear reduction in the number of cells being analyzed, pointing to marked cytotoxicity. Our data confirm the potentiation of cytotoxicity related to proteasome inhibition, in the presence of dopaminergic stimulation.
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Affiliation(s)
- Eleonora Bazzini
- Laboratory of Functional Neurochemistry, Neurological Institute C. Mondino, Pavia, Italy
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21
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Papa L, Gomes E, Rockwell P. Reactive oxygen species induced by proteasome inhibition in neuronal cells mediate mitochondrial dysfunction and a caspase-independent cell death. Apoptosis 2007; 12:1389-405. [PMID: 17415663 DOI: 10.1007/s10495-007-0069-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
While increasing evidence shows that proteasome inhibition triggers oxidative damage, mitochondrial dysfunction and death in neuronal cells, the regulatory relationship among these events is unclear. Using mouse neuronal cells we show that the cytotoxicity induced by mild (0.25 microM) and potent (5.0 microM) doses of the proteasome inhibitor, N-Benzyloxycarbonyl-Ile-Glu (O-t-butyl)-Ala-leucinal, (PSI) involved a dose-dependent increase in caspase activation, overproduction of reactive oxygen species (ROS) and a mitochondrial dysfunction manifested by the translocation of the proapoptotic protein, Bax, from the cytoplasm to the mitochondria, membrane depolarization and the release of cytochrome c and the apoptosis inducing factor (AIF) from mitochondria to the cytoplasm and nucleus, respectively. Whereas caspase or Bax inhibition failed to prevent mitochondrial membrane depolarization and neuronal cell death, pretreatments with the antioxidant N-acetyl-L-cysteine (NAC) or overexpression of the antiapoptotic protein Bcl-xL abrogated these events in cells exposed to mild levels of PSI. These findings implicated ROS as a mediator of PSI-induced cytotoxicity. However, depletions in glutathione and Bcl-xL with potent proteasome inhibition exacerbated this response whereupon survival required the cooperative protection of NAC with Bcl-xL overexpression. Collectively, ROS induced by proteasome inhibition mediates a mitochondrial dysfunction in neuronal cells that culminates in death through caspase- and Bax-independent mechanisms.
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Affiliation(s)
- Luena Papa
- Department of Biological Sciences, Hunter College of The City University of New York, 695 Park Ave, New York, NY 10021, USA
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22
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Lagalwar S, Berry RW, Binder LI. Relation of hippocampal phospho-SAPK/JNK granules in Alzheimer's disease and tauopathies to granulovacuolar degeneration bodies. Acta Neuropathol 2007; 113:63-73. [PMID: 17089132 DOI: 10.1007/s00401-006-0159-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 09/26/2006] [Accepted: 10/12/2006] [Indexed: 11/30/2022]
Abstract
Protein misfolding is a distinguishing feature of a number of neurodegenerative diseases. Accumulation of misfolded protein often results in cellular lesions, the location of lesions correlating with the nature of symptoms. Alzheimer's disease (AD), Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD) and Pick's Disease (PiD) all present with pathological lesions containing hyperphosphorylated filamentous tau protein; however, the location and type of lesion varies. In addition, granulovacuolar degeneration (GVD) bodies have been reported within hippocampal pyramidal neurons in AD, PSP, CBD and PiD tissue. GVDs are defined as electron-dense granules within double membrane-bound cytoplasmic vacuoles. We have previously reported that the phosphorylated form of stress-activated protein kinase/c-Jun N-terminal kinase (p-SAPK/JNK) accumulates in granules within hippocampal pyramidal cell bodies in AD tissue at the time that hyperphosphorylated tau begins to aggregate into early-stage NFTs. We now report that p-SAPK/JNK granules are found within the hippocampal CA1 region of PSP, CBD and PiD cases as well and that these granules are likely GVD bodies. Quantitatively, p-SAPK/JNK granules and GVDs are found in comparable numbers of CA1 cells. Within cells, p-SAPK/JNK granules are distributed throughout the cytoplasm in a manner similar to the distribution of GVDs and a subset of granules co-localize with GVD markers. Ultrastructurally, p-SAPK/JNK granules are located in large cytoplasmic vacuoles, thereby fitting the definition of a GVD body. With the implication of granular p-SAPK/JNK as a marker of GVDs, our study strongly suggests that a heterogeneous group of proteins form GVDs. The mechanism of GVD formation is therefore an interesting one, and is likely separate and distinct from the mechanism of tau inclusion formation.
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Affiliation(s)
- Sarita Lagalwar
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave, Chicago, IL 60611, USA.
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23
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Choy MS, Bay BH, Cheng HC, Cheung NS. PTEN is recruited to specific microdomains of the plasma membrane during lactacystin-induced neuronal apoptosis. Neurosci Lett 2006; 405:120-5. [PMID: 16857313 DOI: 10.1016/j.neulet.2006.06.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2006] [Revised: 06/16/2006] [Accepted: 06/16/2006] [Indexed: 10/24/2022]
Abstract
The tumor suppressor PTEN (phosphatase and tensin homolog deleted from chromosome 10) is a novel phosphatase displaying both protein and lipid phosphatase activities. In the central nervous system, PTEN plays an important role in the regulation of cell growth, differentiation and death. The tumor suppressor function of PTEN is attributed to its phospholipid phosphatase activity that dephosphorylates the plasma membrane phosphatidylinositol-(3,4,5)-triphosphate (PtdIns(3,4,5)P(3)). Since PTEN is normally localized in the cytosol, it needs to be targeted to the plasma membrane to dephosphorylate PtdIns(3,4,5)P(3). We previously demonstrated that lactacystin-induced apoptosis of culture cortical neuron is associated with: (i) cleavage of PTEN (55 kDa) to a 50 kDa truncated form and (ii) accumulation of PTEN and all the truncated PTEN in a detergent-insoluble membrane fraction of the neuronal cells. Herein we demonstrate that a caspase-3 inhibitor suppresses cleavage of PTEN to the 50kDa truncated form in culture cortical neurons in response to lactacystin treatment. Using immunogold transmission electron microscopy, we examined the distribution of PTEN in plasma membrane sheets stripped from cultured cortical neurons with and without treatment of lactacystin. Our results demonstrate that lactacystin treatment induces accumulation of PTEN to the inner surface of the plasma membrane sheets of the neuronal cells. Taken together, our data suggest that caspase-3-like proteases are involved in the conversion of PTEN to a 50-kDa truncated form and that PTEN and its truncated form accumulate at specific microdomains of the plasma membrane in neuronal cells undergoing apoptosis.
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Affiliation(s)
- Meng Shyan Choy
- Departments of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Blk MD7, 8 Medical Drive, Singapore 117597, Singapore
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24
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McLaughlin M, Barrie JA, Karim S, Montague P, Edgar JM, Kirkham D, Thomson CE, Griffiths IR. Processing of PLP in a model of Pelizaeus-Merzbacher disease/SPG2 due to the rumpshaker mutation. Glia 2006; 53:715-22. [PMID: 16506223 DOI: 10.1002/glia.20325] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The rumpshaker mutation of the X-linked myelin proteolipid protein (PLP1) gene causes spastic paraplegia type 2 or a mild form of Pelizaeus-Merzbacher disease in man. The identical mutation occurs spontaneously in mice. Both human and murine diseases are associated with dysmyelination. Using the mouse model, we show that the low steady state levels of PLP result from accelerated proteasomal degradation rather than decreased synthesis. The T(1/2) for degradation of rumpshaker PLP is 11 h compared with 23 h for wild type. A minority of newly synthesized PLP is incorporated into myelin in the correct orientation but at a reduced rate compared with wild type. However, inhibition of proteasomal degradation does not increase the level of PLP incorporated into myelin. As Plp null mice do not have a similar myelin deficiency, it is unlikely that the reduced PLP levels are the main cause of the dysmyelination. Rumpshaker oligodendrocytes also have a reduced level of other myelin proteins, such as MBP, although the mechanisms are not yet defined but are likely to operate at a translational or post-translational level.
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Affiliation(s)
- Mark McLaughlin
- Applied Neurobiology Group, Institute of Comparative Medicine, University of Glasgow, Bearsden Glasgow G61 1QH, Scotland
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25
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Ren QG, Liao XM, Wang ZF, Qu ZS, Wang JZ. The involvement of glycogen synthase kinase-3 and protein phosphatase-2A in lactacystin-induced tau accumulation. FEBS Lett 2006; 580:2503-11. [PMID: 16638578 DOI: 10.1016/j.febslet.2006.03.073] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 03/06/2006] [Accepted: 03/27/2006] [Indexed: 10/24/2022]
Abstract
Here, we demonstrated that lactacystin inhibited proteasome dose-dependently in HEK293 cells stably expressing tau. Simultaneously, it induces accumulation of both non-phosphorylated and hyperphosphorylated tau and decreases the binding of tau to the taxol-stabilized microtubules. Lactacystin activates glycogen synthase kinsase-3 (GSK-3) and decreases the phosphorylation of GSK-3 at serine-9. LiCl inhibits GSK-3 and thus reverses the lactacystin-induced accumulation of the phosphorylated tau. Lactacystin also inhibits protein phosphase-2A (PP-2A) and it significantly increases the level of inhibitor 1 of PP-2A. These results suggest that inhibition of proteasome by lactacystin induces tau accumulation and activation of GSK-3 and inhibition of PP-2A are involved.
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Affiliation(s)
- Qing-Guo Ren
- Department of Pathophysiology, Key Laboratory of Neurological Diseases of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
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26
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Ghanevati M, Miller CA. Phospho-beta-catenin accumulation in Alzheimer's disease and in aggresomes attributable to proteasome dysfunction. J Mol Neurosci 2005; 25:79-94. [PMID: 15781969 DOI: 10.1385/jmn:25:1:079] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2004] [Accepted: 04/24/2004] [Indexed: 11/11/2022]
Abstract
Accumulation of cytoplasmic inclusion bodies in many neurodegenerative diseases, including Alzheimer's disease (AD), might result from dysfunction of the ubiquitin-proteasome system. This system degrades many cellular proteins, including beta-catenin, a member of the Wnt signaling pathway, and a presenilin-1-interacting protein. Phosphorylation of beta-catenin marks it for ubiquitination and rapid proteasomal degradation. We found phospho-beta-catenin accumulated as detergent-insoluble, punctate, cytoplasmic inclusions in hippocampal pyramidal neurons more abundantly in AD than in aged controls. In AD, beta-catenin was ubiquitin conjugated, thus suggesting impaired proteasome-dependent degradation. Phospho-beta-catenin was partially sequestered within granulovacuolar degeneration bodies but not in lysosomes, indicating sequestration within autophagosomes. Exposure of neuronal cultures to proteasome inhibitors induced formation of detergent-insoluble, phospho-beta-catenin-positive cytoplasmic inclusions that coalesced into aggresomes and colocalized with gamma-tubulin and vimentin. These aggregates were associated with apoptotic cell death and with activation of caspase-3, c-Jun-N-terminal kinases, and c-Jun. These findings suggest that phospho-beta-catenin accumulation in AD might result from impaired proteasome function.
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Affiliation(s)
- Mahin Ghanevati
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
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27
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Fekete MR, McBride WH, Pajonk F. Anthracyclines, proteasome activity and multi-drug-resistance. BMC Cancer 2005; 5:114. [PMID: 16159384 PMCID: PMC1242219 DOI: 10.1186/1471-2407-5-114] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Accepted: 09/13/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND P-glycoprotein is responsible for the ATP-dependent export of certain structurally unrelated compounds including many chemotherapeutic drugs. Amplification of P-glycoprotein activity can result in multi-drug resistance and is a common cause of chemotherapy treatment failure. Therefore, there is an ongoing search for inhibitors of P-glycoprotein. Observations that cyclosporin A, and certain other substances, inhibit both the proteasome and P-glycoprotein led us to investigate whether anthracyclines, well known substrates of P-gp, also inhibit the function of the proteasome. METHODS Proteasome function was measured in cell lysates from ECV304 cells incubated with different doses of verapamil, doxorubicin, daunorubicin, idarubicin, epirubicin, topotecan, mitomycin C, and gemcitabine using a fluorogenic peptide assay. Proteasome function in living cells was monitored using ECV304 cells stably transfected with the gene for an ubiquitin/green fluorescent protein fusion protein. The ability of the proteasome inhibitor MG-132 to affect P-glycoprotein function was monitored by fluorescence due to accumulation of daunorubicin in P-glycoprotein overexpressing KB 8-5 cells. RESULTS Verapamil, daunorubicin, doxorubicin, idarubicin, and epirubicin inhibited 26S chymotrypsin-like function in ECV304 extracts in a dose-dependent fashion. With the exception of daunorubicin, 20S proteasome function was also suppressed. The proteasome inhibitor MG-132 caused a dose-dependent accumulation of daunorubicin in KB 8-5 cells that overexpress P-glycoprotein, suggesting that it blocked P-glycoprotein function. CONCLUSION Our data indicate that anthracyclines inhibit the 26S proteasome as well as P-glycoprotein. Use of inhibitors of either pathway in cancer therapy should take this into consideration and perhaps use it to advantage, for example during chemosensitization by proteasome inhibitors.
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Affiliation(s)
- Mirela R Fekete
- Department of Neurology, Bürgerhospital, Tunzhofer Str. 14-16, 70191 Stuttgart, Germany
| | - William H McBride
- Department of Radiation Oncology, Roy E. Coats Labs., David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA90095-1714, USA
| | - Frank Pajonk
- Department of Radiation Oncology, Roy E. Coats Labs., David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA90095-1714, USA
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Yabe T, Kanemitsu K, Sanagi T, Schwartz JP, Yamada H. Pigment epithelium-derived factor induces pro-survival genes through cyclic AMP-responsive element binding protein and nuclear factor kappa B activation in rat cultured cerebellar granule cells: Implication for its neuroprotective effect. Neuroscience 2005; 133:691-700. [PMID: 15893882 DOI: 10.1016/j.neuroscience.2005.03.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2004] [Revised: 02/28/2005] [Accepted: 03/09/2005] [Indexed: 11/21/2022]
Abstract
Pigment epithelium-derived factor (PEDF) protects immature cerebellar granule cell neurons (CGCs) against apoptosis induced by K+ and serum deprivation. However, the precise mechanism of this protection remains unknown. We recently reported that the transcription factor nuclear factor kappa B (NF-kappaB) is activated in PEDF-treated CGCs. Although it is well known that NF-kappaB blocks apoptotic cell death through the induction of pro-survival factors, the effects of PEDF on the expression of these factors are not fully understood. In this study, we employed the use of reverse transcriptase-polymerase chain reaction to analyze the gene expression of certain pro-survival genes and found that genes such as c-IAP1, c-IAP2, FLIPs, A1/Bfl-1 and Mn-SOD were induced in PEDF-treated neurons. On the other hand, no induction was observed of the pro-apoptotic Bcl-2 family members Bax and Bid at any time from 3 to 24 h following PEDF addition. Furthermore, phosphorylation of cyclic AMP-responsive element binding protein (CREB) and increment of nuclear cyclic AMP-response element (CRE)-like DNA binding were observed in PEDF-treated CGCs. The anti-apoptotic effect of PEDF was blocked by overexpression of dominant negative CREB or a mutated form of IkappaBalpha. These results suggested that induction of both CRE- and NF-kappaB-dependent genes is required for the observed neuroprotective effects of PEDF on CGCs.
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Affiliation(s)
- T Yabe
- Kitasato Institute for Life Sciences, Kitasato University, 5-9-1, Shirokane, Tokyo 108-8641, Japan.
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Pajonk F, van Ophoven A, Weissenberger C, McBride WH. The proteasome inhibitor MG-132 sensitizes PC-3 prostate cancer cells to ionizing radiation by a DNA-PK-independent mechanism. BMC Cancer 2005; 5:76. [PMID: 16001975 PMCID: PMC1177933 DOI: 10.1186/1471-2407-5-76] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2005] [Accepted: 07/07/2005] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND By modulating the expression levels of specific signal transduction molecules, the 26S proteasome plays a central role in determining cell cycle progression or arrest and cell survival or death in response to stress stimuli, including ionizing radiation. Inhibition of proteasome function by specific drugs results in cell cycle arrest, apoptosis and radiosensitization of many cancer cell lines. This study investigates whether there is also a concomitant increase in cellular radiosensitivity if proteasome inhibition occurs only transiently before radiation. Further, since proteasome inhibition has been shown to activate caspase-3, which is involved in apoptosis, and caspase-3 can cleave DNA-PKcs, which is involved in DNA-double strand repair, the hypothesis was tested that caspase-3 activation was essential for both apoptosis and radiosensitization following proteasome inhibition. METHODS Prostate carcinoma PC-3 cells were treated with the reversible proteasome inhibitor MG-132. Cell cycle distribution, apoptosis, caspase-3 activity, DNA-PKcs protein levels and DNA-PK activity were monitored. Radiosensitivity was assessed using a clonogenic assay. RESULTS Inhibition of proteasome function caused cell cycle arrest and apoptosis but this did not involve early activation of caspase-3. Short-time inhibition of proteasome function also caused radiosensitization but this did not involve a decrease in DNA-PKcs protein levels or DNA-PK activity. CONCLUSION We conclude that caspase-dependent cleavage of DNA-PKcs during apoptosis does not contribute to the radiosensitizing effects of MG-132.
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Affiliation(s)
- Frank Pajonk
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA90095-1714, USA
| | - Arndt van Ophoven
- Department of Urology, University Hospital Münster, Albert-Schweitzer-Straße 33, D-48149 Münster Germany
| | - Christian Weissenberger
- Department of Radiation Oncology, University Hospital Freiburg, Robert-Koch-Straße 3, D-79106 Freiburg, Germany
| | - William H McBride
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles, CA90095-1714, USA
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30
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Yew EHJ, Cheung NS, Choy MS, Qi RZ, Lee AYW, Peng ZF, Melendez AJ, Manikandan J, Koay ESC, Chiu LL, Ng WL, Whiteman M, Kandiah J, Halliwell B. Proteasome inhibition by lactacystin in primary neuronal cells induces both potentially neuroprotective and pro-apoptotic transcriptional responses: a microarray analysis. J Neurochem 2005; 94:943-56. [PMID: 15992382 DOI: 10.1111/j.1471-4159.2005.03220.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Although inhibition of the ubiquitin proteasome system has been postulated to play a key role in the pathogenesis of neurodegenerative diseases, studies have also shown that proteasome inhibition can induce increased expression of neuroprotective heat-shock proteins (HSPs). The global gene expression of primary neurons in response to treatment with the proteasome inhibitor lactacystin was studied to identify the widest range of possible pathways affected. Our results showed changes in mRNA abundance, both at different time points after lactacystin treatment and at different lactacystin concentrations. Genes that were differentially up-regulated at the early time point but not when most cells were undergoing apoptosis might be involved in an attempt to reverse proteasome inhibitor-mediated apoptosis and include HSP70, HSP22 and cell cycle inhibitors. The up-regulation of HSP70 and HSP22 appeared specific towards proteasome inhibitor-mediated cell death. Overexpression of HSP22 was found to protect against proteasome inhibitor-mediated loss of viability by up to 25%. Genes involved in oxidative stress and the inflammatory response were also up-regulated. These data suggest an initial neuroprotective pathway involving HSPs, antioxidants and cell cycle inhibitors, followed by a pro-apoptotic response possibly mediated by inflammation, oxidative stress and aberrant activation of cell cycle proteins.
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Affiliation(s)
- Elaine Hau Jin Yew
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, Singapore
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31
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Flood F, Murphy S, Cowburn R, Lannfelt L, Walker B, Johnston J. Proteasome-mediated effects on amyloid precursor protein processing at the gamma-secretase site. Biochem J 2005; 385:545-50. [PMID: 15473868 PMCID: PMC1134727 DOI: 10.1042/bj20041145] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Abeta (beta-amyloid) peptides are found aggregated in the cortical amyloid plaques associated with Alzheimer's disease neuropathology. Inhibition of the proteasome alters the amount of Abeta produced from APP (amyloid precursor protein) by various cell lines in vitro. Proteasome activity is altered during aging, a major risk factor for Alzheimer's disease. In the present study, a human neuroblastoma cell line expressing the C-terminal 100 residues of APP (SH-SY5Y-SPA4CT) was used to determine the effect of proteasome inhibition, by lactacystin and Bz-LLL-COCHO (benzoyl-Leu-Leu-Leu-glyoxal), on APP processing at the gamma-secretase site. Proteasome inhibition caused a significant increase in Abeta peptide levels in medium conditioned by SH-SY5Y-SPA4CT cells, and was also associated with increased cell death. APP is a substrate of the apoptosis-associated caspase 3 protease, and we therefore investigated whether the increased Abeta levels could reflect caspase activation. We report that caspase activation was not required for proteasome-inhibitor-mediated effects on APP (SPA4CT) processing. Cleavage of Ac-DEVD-AMC (N-acetyl-Asp-Glu-Val-Asp-7-amino-4-methylcoumarin), a caspase substrate, was reduced following exposure of SH-SY5Y-SPA4CT cells to lactacystin, and co-treatment of cells with lactacystin and a caspase inhibitor [Z-DEVD-FMK (benzyloxycarbonyl-Val-Ala-DL-Asp-fluoromethylketone)] resulted in higher Abeta levels in medium, augmenting those seen with lactacystin alone. This study indicated that proteasome inhibition could increase APP processing specifically at the gamma-secretase site, and increase release of Abeta, in the absence of caspase activation. This indicates that the decline in proteasome function associated with aging would contribute to increased Abeta levels.
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Affiliation(s)
- Fiona Flood
- *Karolinska Institute, Neurotec Department, Division of Experimental Geriatrics, Huddinge, S-14186, Sweden
| | - Suzanne Murphy
- †Queen's University, Belfast, School of Biology and Biochemistry, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, U.K
| | - Richard F. Cowburn
- *Karolinska Institute, Neurotec Department, Division of Experimental Geriatrics, Huddinge, S-14186, Sweden
| | - Lars Lannfelt
- ‡Uppsala University Hospital, Department of Geriatric Medicine, Uppsala, S-75125, Sweden
| | - Brian Walker
- §Queen's University, Belfast, School of Pharmacy, McClay Research Centre, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, U.K
| | - Janet A. Johnston
- †Queen's University, Belfast, School of Biology and Biochemistry, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, U.K
- To whom correspondence should be addressed (email )
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32
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Tremper-Wells B, Vallano ML. Nuclear calpain regulates Ca2+-dependent signaling via proteolysis of nuclear Ca2+/calmodulin-dependent protein kinase type IV in cultured neurons. J Biol Chem 2004; 280:2165-75. [PMID: 15537635 DOI: 10.1074/jbc.m410591200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Accumulating evidence indicates that calpains can reside in or translocate to the cell nucleus, but their functions in this compartment remain poorly understood. Dissociated cultures of cerebellar granule cells (GCs) demonstrate improved long-term survival when their growth medium is supplemented with depolarizing agents that stimulate Ca(2+) influx and activate calmodulin-dependent signaling cascades, notably 20 mm KCl. We previously observed Ca(2+)-dependent down-regulation of Ca(2+)/calmodulin-dependent protein kinase (CaMK) type IV, which was attenuated by calpain inhibitors, in GCs supplemented with 20 mm KCl (Tremper-Wells, B., Mathur, A., Beaman-Hall, C. M., and Vallano, M. L. (2002) J. Neurochem. 81, 314-324). CaMKIV is highly enriched in the nucleus and thought to be critical for improved survival. Here, we demonstrate by immunolocalization/confocal microscopy and subcellular fractionation that the regulatory and catalytic subunits of m-calpain are enriched in GC nuclei, including GCs grown in medium containing 5 mm KCl. Calpain-mediated proteolysis of CaMKIV is selective, as several other nuclear and non-nuclear calpain substrates were not degraded under chronic depolarizing culture conditions. Depolarization and Ca(2+)-dependent down-regulation of CaMKIV were associated with significant alterations in other components of the Ca(2+)-CaMKIV signaling cascade: the ratio of phosphorylated to total cAMP response element-binding protein (a downstream CaMKIV substrate) was reduced by approximately 10-fold, and the amount of CaMK kinase (an upstream activator of CaMKIV) protein and mRNA was significantly reduced. We hypothesize that calpain-mediated CaMKIV proteolysis is an autoregulatory feedback response to sustained activation of a Ca(2+)-CaMKIV signaling pathway, resulting from growth of cultures in medium containing 25 mm KCl. This study establishes nuclear m-calpain as a regulator of CaMKIV and associated signaling molecules under conditions of sustained Ca(2+) influx.
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Affiliation(s)
- Barbara Tremper-Wells
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York 13210, USA
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33
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Thompson HGR, Harris JW, Brody JP. Post-translationally modified S12, absent in transformed breast epithelial cells, is not associated with the 26S proteasome and is induced by proteasome inhibitor. Int J Cancer 2004; 111:338-47. [PMID: 15221960 DOI: 10.1002/ijc.20261] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The 26S proteasome, consisting of the 20S core and 19S regulatory complexes, regulates intracellular protein concentration through proteolytic degradation of targeted substrates. Composition of the 19S regulatory complex as well as posttranslational modifications of the 19S subunits can effectively regulate the activity of the 26S proteasome. Aberrant activity of the 26S proteasome affects the cell cycle, apoptosis and other cellular processes related to cancer. Recent data show an additional proteasome-independent role of 19S subunits in transcriptional regulation. S12 (Rpn8), the human homologue of mouse Mov-34, is a non-ATPase 19S regulatory subunit of the 26S proteasome. Previous studies have identified phosphorylated S12. In our study, we identify a modified S12 isoform (S12-M) with distinct biochemical properties. The S12-M isoform was found in 6 normal, but not 4 transformed, breast epithelial cell lines. Modification of S12 protein can be induced in vitro by addition of the proteasome inhibitor PSI. Modified and unmodified S12 have similar mass, but different isoelectric points, consistent with phosphorylation. In normal cells, unmodified S12 associates with the 26S proteasome, while modified S12-M does not. Whereas transformed cell line nuclei contain neither S12 isoform, S12-M is predominantly cytosolic in normal cells, with the unmodified S12 present in both the nuclei and cytosol. Together with the role of 19S subunits in transcriptional regulation, homology between S12 and eIF3 and TFIIH subunits, coelution with immunoproteasome subunits, and differential posttranslational modification and nuclear localization, these data suggest a differential nuclear function of modified and unmodified S12 in cancer.
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Affiliation(s)
- H Garrett R Thompson
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697-2715, USA
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34
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Cheung NS, Choy MS, Halliwell B, Teo TS, Bay BH, Lee AYW, Qi RZ, Koh VH, Whiteman M, Koay ESC, Chiu LL, Zhu HJ, Wong KP, Beart PM, Cheng HC. Lactacystin-induced apoptosis of cultured mouse cortical neurons is associated with accumulation of PTEN in the detergent-resistant membrane fraction. Cell Mol Life Sci 2004; 61:1926-34. [PMID: 15289934 PMCID: PMC11138484 DOI: 10.1007/s00018-004-4127-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Revised: 05/26/2004] [Accepted: 06/05/2004] [Indexed: 10/26/2022]
Abstract
The tumor suppressor function of PTEN is attributed to its phospholipid phosphatase activity that dephosphorylates the plasma membrane phosphatidylinositol-(3,4,5)-triphosphate [PtdIns(3,4,5)P3]. Implicit in this notion is that PTEN needs to be targeted to the plasma membrane to dephosphorylate PtdIns(3,4,5)P3. However, the recruitment of PTEN to the plasma membrane is not fully understood. Here, we demonstrate PTEN accumulation in the detergent-insoluble fraction of neuronal cells in response to treatment by the proteasome inhibitor lactacystin. First, lactacystin induces apoptosis and the activation of caspase-3 in cultured cortical neurons. Second, PTEN undergoes proteolysis to form a truncated 50-kDa form that lacks parts of its C-terminal tail. Third, the truncated PTEN is stably associated with the detergent-insoluble fraction in which the plasma membrane marker protein flotillin-1 resides. Taken together, our results suggest that truncation and accumulation of PTEN to the detergent-insoluble membrane fraction are two events associated with the apoptotic signals of the proteasome inhibitor in cortical neurons.
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Affiliation(s)
- N S Cheung
- Department of Biochemistry, National University of Singapore, 117597, Singapore, Singapore.
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35
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Thompson HGR, Harris JW, Lin L, Brody JP. Identification of the protein Zibra, its genomic organization, regulation, and expression in breast cancer cells. Exp Cell Res 2004; 295:448-59. [PMID: 15093743 DOI: 10.1016/j.yexcr.2004.01.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2003] [Revised: 01/14/2004] [Indexed: 11/24/2022]
Abstract
The mRNA that encodes zibra (zinc, in-between-ring finger, ubiquitin-associated domain), previously known as hypothetical protein FLJ10111, or RNF31 is expressed in several distinct cancers. Little is known about the genomic organization, expression, or regulation of zibra. Using RNA ligase-mediated rapid amplification of cDNA ends (RLM-RACE), we cloned the full-length zibra cDNA from a transformed breast cell line. We identified a novel exon, the 5' untranslated region including the +1 start site, and three alternatively spliced zibra transcripts. The zibra protein contains three zinc ring-finger motifs, an ubiquitin-associated domain, and an in-between-ring-finger domain, characteristic of ubiquitin ligases. We obtained an antibody to zibra and confirmed the presence of translated zibra protein for the first time. Promoter studies localized a core element responsible for basal activity to a 14-bp region in the 5' untranslated region. Although there are numerous consensus Ets factor binding sites in the zibra promoter, we found no affect on promoter activity from Ets-1, PDEF, or PEA-3/E1A-F. Treatment of cells with the proteasome inhibitor I (PSI) decreased zibra protein to an undetectable level after 8 h. Zibra remained undetectable even after 32 h, while mRNA levels remained essentially unchanged. In conclusion, zibra is a translationally regulated putative ubiquitin ligase that is frequently overexpressed in different forms of cancer.
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Affiliation(s)
- H Garrett R Thompson
- Department of Biomedical Engineering, University of California-Irvine, Irvine, CA 92697-2715, USA
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36
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Canu N, Calissano P. In vitro cultured neurons for molecular studies correlating apoptosis with events related to Alzheimer disease. THE CEREBELLUM 2004; 2:270-8. [PMID: 14964686 DOI: 10.1080/14734220310004289] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
This short review analyses the possible molecular events linking a general program of death such as apoptosis to highly specific intracellular pathways involving the function and degradation of two proteins--tau and amyloid precursor protein--which in their aggregated state constitute the hallmark of Alzheimer disease. By surveying the recent studies carried out in 'in vitro' neuronal cultures--with special emphasis to cerebellar granule neurons--the apparent correlation between onset of apoptosis, tau cleavage with formation of potential toxic fragments, and activation of an amyloidogenic route are discussed. Within this framework, proteasomes seem to play a crucial role upstream of the proteolytic cascade involving calpain(s) and caspase(s) by contributing to tau and amyloid precursor protein-altered breakdown and consequent tendency to aggregation of their degradation fragments. Thus, apoptotic death due to altered supply of anti apoptotic agents, neurotrophic factors, deafferentiation or other causes, may constitute a major trigger of the onset of Alzheimer disease.
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Affiliation(s)
- Nadia Canu
- Department of Neuroscience, University of Tor Vergata, Rome, Italy.
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37
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Zhang F, Su K, Yang X, Bowe DB, Paterson AJ, Kudlow JE. O-GlcNAc modification is an endogenous inhibitor of the proteasome. Cell 2004; 115:715-25. [PMID: 14675536 DOI: 10.1016/s0092-8674(03)00974-7] [Citation(s) in RCA: 322] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ubiquitin proteasome system classically selects its substrates for degradation by tagging them with ubiquitin. Here, we describe another means of controlling proteasome function in a global manner. The 26S proteasome can be inhibited by modification with the enzyme, O-GlcNAc transferase (OGT). This reversible modification of the proteasome inhibits the proteolysis of the transcription factor Sp1 and a hydrophobic peptide through inhibition of the ATPase activity of 26S proteasomes. The Rpt2 ATPase in the mammalian proteasome 19S cap is modified by O-GlcNAc in vitro and in vivo and as its modification increases, proteasome function decreases. This mechanism may couple proteasomes to the general metabolic state of the cell. The O-GlcNAc modification of proteasomes may allow the organism to respond to its metabolic needs by controlling the availability of amino acids and regulatory proteins.
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Affiliation(s)
- Fengxue Zhang
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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38
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Sullivan PG, Dragicevic NB, Deng JH, Bai Y, Dimayuga E, Ding Q, Chen Q, Bruce-Keller AJ, Keller JN. Proteasome inhibition alters neural mitochondrial homeostasis and mitochondria turnover. J Biol Chem 2004; 279:20699-707. [PMID: 14742431 DOI: 10.1074/jbc.m313579200] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Inhibition of proteasome activity occurs in normal aging and in a wide variety of neurodegenerative conditions including Alzheimer's disease and Parkinson's disease. Although each of these conditions is also associated with mitochondrial dysfunction potentially mediated by proteasome inhibition, the relationship between proteasome inhibition and the loss of mitochondrial homeostasis in each of these conditions has not been fully elucidated. In this study, we conducted experimentation in order to begin to develop a more complete understanding of the effects proteasome inhibition has on neural mitochondrial homeostasis. Mitochondria within neural SH-SY5Y cells exposed to low level proteasome inhibition possessed similar morphological features and similar rates of electron transport chain activity under basal conditions as compared with untreated neural cultures of equal passage number. Despite such similarities, maximal complex I and complex II activities were dramatically reduced in neural cells subject to proteasome inhibition. Proteasome inhibition also increased mitochondrial reactive oxygen species production, reduced intramitochondrial protein translation, and increased cellular dependence on glycolysis. Finally, whereas proteasome inhibition generated cells that consistently possessed mitochondria located in close proximity to lysosomes with mitochondria present in the cellular debris located within autophagosomes, increased levels of lipofuscin suggest that impairments in mitochondrial turnover may occur following proteasome inhibition. Taken together, these data demonstrate that proteasome inhibition dramatically alters specific aspects of neural mitochondrial homeostasis and alters lysosomal-mediated degradation of mitochondria with both of these alterations potentially contributing to aging and age-related disease in the nervous system.
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Affiliation(s)
- Patrick G Sullivan
- Department of Anatomy and Neurobiology, 205 Sanders-Brown Building, University of Kentucky, Lexington, KY 40536, USA
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39
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Ghibelli L, Mengoni F, Lichtner M, Coppola S, De Nicola M, Bergamaschi A, Mastroianni C, Vullo V. Anti-apoptotic effect of HIV protease inhibitors via direct inhibition of calpain. Biochem Pharmacol 2003; 66:1505-12. [PMID: 14555228 DOI: 10.1016/s0006-2952(03)00505-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Treatment with drugs designed to inhibit the HIV protease ameliorates immune functions in AIDS patients, reducing cell deletion by apoptosis even in the absence of inhibition of viral spread. This suggests that they interact with the intrinsic apoptotic signaling. We found that caspases, the main executioner of the apoptotic process, are not directly inhibited. In search for the mechanism responsible for their anti-apoptotic effect, we have found that indinavir and ritonavir are able to inhibit apoptosis only in those cell systems where apoptosis involves the activation of calpains. They directly inhibit a calpain-like activity expressed in lysates from apoptotic cells, to the same extent as commercially available calpain inhibitor 1. In in vitro assays with purified calpains, indinavir and ritonavir strongly inhibit m-calpain, and moderately mu-calpain. These results have great therapeutic implications, going beyond AIDS treatment, since many degenerative disorders involve abnormal calpain activation, indicating calpain as an ideal pharmacological target. Indinavir and ritonavir, potent m-calpain inhibitors, largely used since several years on humans without important negative side effects, may become powerful tools against those pathologies.
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Affiliation(s)
- Lina Ghibelli
- Dipartimento di Biologia, Universita' di Roma Tor Vergata, via Ricerca Scientifica, 00133 Rome, Italy.
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40
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Donaldson KM, Li W, Ching KA, Batalov S, Tsai CC, Joazeiro CAP. Ubiquitin-mediated sequestration of normal cellular proteins into polyglutamine aggregates. Proc Natl Acad Sci U S A 2003; 100:8892-7. [PMID: 12857950 PMCID: PMC166409 DOI: 10.1073/pnas.1530212100] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2003] [Indexed: 11/18/2022] Open
Abstract
A hallmark of most neurodegenerative diseases, including those caused by polyglutamine expansion, is the formation of ubiquitin (Ub)-positive protein aggregates in affected neurons. This finding suggests that the Ub system may be involved in common mechanisms underlying these otherwise unrelated diseases. Here we report the finding of ataxin-3 (Atx-3), whose mutation is implicated in the neurodegenerative disease spinocerebellar ataxia type 3, in a bioinformatics search of the human genome for components of the Ub system. We show that wild-type Atx-3 is a Ub-binding protein and that the interaction of Atx-3 with Ub is mediated by motifs homologous to those found in a proteasome subunit. Both wild-type Atx-3 and the otherwise unrelated Ub-binding protein p62/Sequestosome-1 have been shown to be sequestered into aggregates in affected neurons in several neurodegenerative diseases, but the mechanism for this recruitment has remained unclear. In this article, we show that functional Ub-binding motifs in Atx-3 and p62 proteins are required for the localization of both proteins into aggregates in a cell-based assay that recapitulates several features of polyglutamine disease. We propose that the Ub-mediated sequestration of essential Ub-binding protein(s) into aggregates may be a common mechanism contributing to the pathogenesis of neurodegenerative diseases.
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Affiliation(s)
- Kathryn M Donaldson
- Department of Cancer and Cell Biology, Genomics Institute of the Novartis Research Foundation (GNF), 10675 John J. Hopkins Drive, San Diego, CA 92121, USA
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41
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Ding Q, Reinacker K, Dimayuga E, Nukala V, Drake J, Butterfield DA, Dunn JC, Martin S, Bruce-Keller AJ, Keller JN. Role of the proteasome in protein oxidation and neural viability following low-level oxidative stress. FEBS Lett 2003; 546:228-32. [PMID: 12832045 DOI: 10.1016/s0014-5793(03)00582-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Numerous studies suggest that proteasome inhibition may play a causal role in mediating the increased levels of protein oxidation and neuron death observed in conditions associated with oxidative stress. In the present study we demonstrate that administration of non-toxic levels of oxidative stress does not result in impairment of 20S/26S proteasome activity, and actually increases the expression of specific proteasome subunits. Non-toxic levels of oxidative stress were observed to elevate the amount of protein oxidation in the presence of preserved proteasomal function, suggesting that proteasome inhibition may not mediate increases in protein oxidation following low-level oxidative stress. Preserving basal proteasome function appears to be critical to preventing the neurotoxicity of low-level oxidative stress, based on the ability of proteasome inhibitor treatment to exacerbate oxidative stress toxicity. Taken together, these data indicate that maintaining neural proteasome function may be critical to preventing neurotoxicity, but not the increase in protein oxidation, following low-level oxidative stress.
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Affiliation(s)
- Qunxing Ding
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, KY 40536, USA
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42
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Ding Q, Dimayuga E, Martin S, Bruce-Keller AJ, Nukala V, Cuervo AM, Keller JN. Characterization of chronic low-level proteasome inhibition on neural homeostasis. J Neurochem 2003; 86:489-97. [PMID: 12871590 DOI: 10.1046/j.1471-4159.2003.01885.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Increasing evidence suggests that proteasome inhibition plays a causal role in promoting the neurodegeneration and neuron death observed in multiple disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD). The ability of severe and acute inhibition of proteasome function to induce neuron death and neuropathology similar to that observed in AD and PD is well documented. However, at present the effects of chronic low-level proteasome inhibition on neural homeostasis has not been elucidated. In order to determine the effects of chronic low-level proteasome inhibition on neural homeostasis, we conducted studies in individual colonies of neural SH-SY5Y cells that were isolated following continual exposure to low concentrations (100 nm) of the proteasome inhibitor MG115. Clonal cell lines appeared morphologically similar to control cultures but exhibited significantly different rates of both proliferation and differentiation. Elevated levels of protein oxidation and protein insolubility were observed in clonal cell lines, with all clonal cell lines being more resistant to neural death induced by serum withdrawal and oxidative stress. Interestingly, clonal cell lines demonstrated evidence for increased macroautophagy, suggesting that chronic low-level proteasome inhibition may cause an excessive activation of the lysosomal system. Taken together, these data indicate that chronic low-level proteasome inhibition has multiple effects on neural homeostasis, and suggests that studying the effects of chronic low-level proteasome inhibition may be useful in understanding the relationship between protein oxidation, protein insolubility, proteasome function, macroautophagy and neural viability in AD and PD.
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Affiliation(s)
- Qunxing Ding
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, Kentucky 40536-0230, USA.
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43
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Thompson HGR, Harris JW, Wold BJ, Lin F, Brody JP. p62 overexpression in breast tumors and regulation by prostate-derived Ets factor in breast cancer cells. Oncogene 2003; 22:2322-33. [PMID: 12700667 DOI: 10.1038/sj.onc.1206325] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
p62 is a multifunctional cytoplasmic protein able to noncovalently bind ubiquitin and several signaling proteins, suggesting a regulatory role connected to the ubiquitin-proteasome pathway. No studies to date have linked p62 protein expression with pathological states. Here we demonstrate the overabundance of p62 protein in malignant breast tissue relative to normal breast tissue. The proteasome inhibitor PSI increased p62 mRNA and protein; however, PSI treatment of breast epithelial cells transfected with the p62 promoter did not affect promoter activity. High levels of prostate-derived Ets factor (PDEF) mRNA have been identified in breast cancer compared to normal breast. Only the PSA and maspin promoters have been identified as targets of this transcription factor. Here we show that PDEF stimulates the p62 promoter through at least two sites, and likely acts as a coactivator. PSI treatment abrogates the PDEF-stimulated increase of p62 promoter activity by 50%. Thus, multiple mechanisms for the induction of p62 exist. We conclude that (1) p62 protein is overexpressed in breast cancer; (2) p62 mRNA and protein increase in response to PSI, with no change of basal promoter activity; (3) PDEF upregulates p62 promoter activity through at least two sites; and (4) PSI downregulates PDEF-induced p62 promoter activation through one of these sites.
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MESH Headings
- Acetylcysteine/analogs & derivatives
- Acetylcysteine/pharmacology
- Adaptor Proteins, Signal Transducing
- Breast/cytology
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carrier Proteins/biosynthesis
- Carrier Proteins/genetics
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Computer Systems
- Cysteine Endopeptidases/metabolism
- Cysteine Proteinase Inhibitors/pharmacology
- Epithelial Cells/drug effects
- Epithelial Cells/metabolism
- Female
- Gene Expression Regulation, Neoplastic/drug effects
- Gene Expression Regulation, Neoplastic/genetics
- Humans
- Leupeptins/pharmacology
- Multienzyme Complexes/metabolism
- Neoplasm Proteins/biosynthesis
- Neoplasm Proteins/genetics
- Oligopeptides/pharmacology
- Promoter Regions, Genetic/genetics
- Proteasome Endopeptidase Complex
- Proteins
- Proto-Oncogene Proteins c-ets
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- RNA, Neoplasm/biosynthesis
- RNA, Neoplasm/genetics
- Regulatory Sequences, Nucleic Acid
- Reverse Transcriptase Polymerase Chain Reaction
- Sequestosome-1 Protein
- Transcription Factors/antagonists & inhibitors
- Transcription Factors/biosynthesis
- Transcription Factors/genetics
- Transcription Factors/physiology
- Transcription, Genetic
- Transfection
- Tumor Cells, Cultured/drug effects
- Tumor Cells, Cultured/metabolism
- Ubiquitin/metabolism
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Affiliation(s)
- H Garrett R Thompson
- Department of Biomedical Engineering, University of California, CA 92697-2715, USA
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Lopez Salon M, Pasquini L, Besio Moreno M, Pasquini JM, Soto E. Relationship between beta-amyloid degradation and the 26S proteasome in neural cells. Exp Neurol 2003; 180:131-43. [PMID: 12684027 DOI: 10.1016/s0014-4886(02)00060-2] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Beta-amyloid peptide (Abeta) plays a central role in mediating neurotoxicity and in the formation of senile plaques in Alzheimer's disease (AD). The investigation of the roles of ubiquitin (Ub) in the process underlying the association of abnormal protein with the inclusion bodies that characterize AD is of great importance for the further understanding of this disorder. We have used primary cultures of cortical neurons and astrocytes to investigate the participation of the Ub-proteasome pathway in the degradation of Abeta and the effect of Abeta(1-42) and of the fragment Abeta(25-35) upon neural cells. We have found that Abeta(25-35) and Abeta(1-42) produce a significant increase in Ub-protein conjugates and in the expression of the Ub-activating enzyme E1. On the other hand, beta peptides inhibited the proteolytic activities of the 26S proteasome. When the proteolytic activity of the 26S proteasome was inhibited with lactacystin, there was a marked decrease in Abeta(1-42) degradation, suggesting that the peptide, in both astrocytes and neurons, could be a possible substrate of this enzymatic complex. Treatment of the cultures with lactacystin prior to the exposure to Abeta produced a significant decrease in cell viability, possibly as a consequence of the inhibition of Abeta degradation leading to a persistent exposure of the cells to the amyloidogenic peptide which results in cell death. Alterations in the Ub-proteasome pathway in AD could affect the normal proteolytic removal of Abeta, leading to an abnormal accumulation of Abeta(1-42).
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Affiliation(s)
- M Lopez Salon
- Departamento de Química Biológica, Instituto de Química y Fisicoquímica Biológicas, UBA-CONICET, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, 1113 Buenos Aires, Argentina
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Yu LY, Korhonen L, Martinez R, Jokitalo E, Chen Y, Arumäe U, Lindholm D. Regulation of sympathetic neuron and neuroblastoma cell death by XIAP and its association with proteasomes in neural cells. Mol Cell Neurosci 2003; 22:308-18. [PMID: 12691733 DOI: 10.1016/s1044-7431(02)00038-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
XIAP (X chromosome-linked inhibitor of apoptosis protein) has been shown to inhibit cell death in a variety of cells. XIAP binds to active caspases, but XIAP also has a carboxy-terminal RING domain that can regulate cell death via protein degradation. Here we have studied the function of full-length and RING-deleted XIAP in mouse sympathetic neurons microinjected with expression plasmids and in neuroblastoma cells stably overexpressing these proteins. Both full-length and RING-deleted XIAP-protected sympathetic neurons against death induced by nerve growth factor (NGF) withdrawal to about the same extent. However, the two proteins were differentially localized in transfected neurons, with RING-deleted XIAP present in the cytoplasm and full-length XIAP found mostly in cytoplasmic protein aggregates, as revealed by transmission electron microscopy. The occurrence of these aggregates was blocked by lactacystin, a proteasome inhibitor. In neuroblastoma cells, RING-deleted XIAP protected against death induced by staurosporine, thapsigargin, or serum withdrawal, whereas full-length XIAP was without effect. Full-length, but not RING-deleted, XIAP was degraded and ubiquitinated in the neuroblastoma cells. The results show that the presence of the RING domain differentially affected the neuroprotective ability of XIAP in sensory neurons and neuroblastoma cells. The RING domain was essentially required for the proteasomal association of XIAP and for its ubiquitination.
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Affiliation(s)
- Li-Ying Yu
- Program of Molecular Neurobiology, Institute of Biotechnology, University of Helsinki, Finland
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Chapter 15 Factors Underlying the Selective Vulnerability of Motor Neurons to Neurodegeneration. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1877-3419(09)70116-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Sang C, Kobayashi Y, Du J, Katsumo M, Adachi H, Doyu M, Sobue G. c-Jun N-terminal kinase pathway mediates Lactacystin-induced cell death in a neuronal differentiated Neuro2a cell line. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 108:7-17. [PMID: 12480174 DOI: 10.1016/s0169-328x(02)00460-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The ubiquitin-proteasome pathway is an intracellular protein degradation pathway responsible for degradation of many regulatory proteins that must be rapidly eliminated normally. Some recent studies reported that a proteasome dysfunction was involved in the pathogenesis of neurodegenerative diseases. Thus, there is now considerable interest in the possible role of proteasome in this regard. Here we show that inhibition of proteasomal function by Lactacystin-induced cell death in a neuronal differentiated Neuro2a (nN2a) cell line but not in an undifferentiated Neuro2a (N2a) cell line. Cell death was accompanied by both the activation of c-Jun N-terminal kinase, p38 and caspase-3. A pan-caspase inhibitor, Z-VAD-FMK, or SB203580, a p38 inhibitor could not inhibit cell death induced by Lactacystin, whereas nN2a cell lines with stable expression of the dominant negative mutant of c-Jun N-terminal kinase showed a remarkable suppression of cell death. Lactacystin-induced cell death is mediated through the c-Jun N-terminal kinase pathway but not the caspase-dependent pathway in a nN2a cell line. Our results shed light on the association among the proteasomal dysfunction, JNK pathway and neuronal cell death, leading to the elucidation of its possible role in the pathogenesis of neurodegenerative diseases.
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Affiliation(s)
- Chen Sang
- Department of Neurology, Nagoya University, Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Aichi, Japan
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Pasquini LA, Besio Moreno M, Lopez Salon M, Soto EF. Apoptosis in Schwann cell cultures is closely interrelated with the activity of the ubiquitin-proteasome proteolytic pathway. Neurochem Res 2002; 27:1401-19. [PMID: 12512944 DOI: 10.1023/a:1021631901827] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Although the participation of the ubiquitin-dependent pathway and of the proteasome in apoptosis has been proposed, its role in this process is not yet clearly defined. In previous studies, we have shown that in the central nervous system of the rat, programmed cell death and the ubiquitin-dependent proteolytic pathway are closely related to each other and that different types of neurons and of glial cells, shown different types of correlation between the two phenomena. In this work, we have used lactacystin, a highly specific inhibitor of the proteasome, to explore in Schwann cell cultures the relationship between the activity of the Ub-dependent pathway and apoptosis. Apoptosis was explored analyzing changes in nuclear morphology, using the Annexin V assay and by flow cytometry. Activity of caspase-3 was also measured. Changes in the levels of ubiquitin-protein conjugates and of the ubiquitin activating enzymes, E1, as well as expression of proteins that instruct the cells to apoptosis (p53, NFkappaB-IkappaB, Bcl2), or that participate in the control and regulation of the cell cycle, were also examined. Our results indicate that the decrease in the activity of the proteasome induced by lactacystin in Schwann cells, induces apoptotic cell death through changes in the concentration of certain key proteins that are involved in the apoptosis-signaling pathways.
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Affiliation(s)
- L A Pasquini
- Instituto de Química y Fisicoquimica Biológica, UBA-CONICET and Departamento de Química Biológica-Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junin 956-Buenos Aires C113AAD, Argentina
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Kessler BM, Glas R, Ploegh HL. MHC class I antigen processing regulated by cytosolic proteolysis-short cuts that alter peptide generation. Mol Immunol 2002; 39:171-9. [PMID: 12200049 DOI: 10.1016/s0161-5890(02)00100-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cytotoxic T lymphocyte (CTL)-mediated immune responses rely on the efficiency of MHC class I ligand generation and presentation by antigen presenting cells (APCs). Whereas the abnormal expression of MHC molecules and transporters associated with antigen processing (TAPs) are commonly discussed as factors that modulate antigen presentation, much less is known about possible regulatory mechanisms at the level of proteolysis responsible for the generation of antigenic peptides. The ubiquitin-proteasome system is recognized as the major component responsible for this process in the cytosol and its activity can be regulated by cytokines, such as IFN-gamma. However, new evidence suggests the involvement of other proteases that can contribute to cytosolic proteolysis and therefore, to the quality and quantity of antigen production. Here, we review recent findings on an increasing number of proteolytic enzymes linked to antigen presentation, and we discuss how regulation of cytosolic protease activities might have implications for immune escape mechanisms that could be used by tumor cells and pathogens.
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Affiliation(s)
- Benedikt M Kessler
- Department of Pathology, Harvard Medical School, Room 137, Building D2, 200 Longwood Avenue, Boston, MA 02115, USA
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Halliwell B. Hypothesis: proteasomal dysfunction: a primary event in neurogeneration that leads to nitrative and oxidative stress and subsequent cell death. Ann N Y Acad Sci 2002; 962:182-94. [PMID: 12076974 DOI: 10.1111/j.1749-6632.2002.tb04067.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is proposed that a primary mechanism leading to neuronal cell death in common neurodegenerative diseases is interference with proteasome function. This can involve genetic defects, direct inactivation of the proteasome (e.g., by reactive oxygen species), or overloading with proteins. The latter can be caused by excessive production of normal proteins or by the formation of poorly degradable proteins as a result of genetic mutations, faulty posttranslational modification, or protein modification by reactive oxygen or nitrogen species. Blockage of the proteasome leads to increased oxidative and nitrative stress, the latter apparently due to upregulation of nitric oxide synthase. Thus, agents that increase proteasome function may be generally neuroprotective, as may be NOS inhibitors. Proteasome inhibitors should be used with caution as therapeutic agents.
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Affiliation(s)
- Barry Halliwell
- Department of Biochemistry, Faculty of Medicine, National University of Singapore, Singapore.
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