301
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Derlin-1-immunopositive inclusions in patients with Alzheimerʼs disease. Neuroreport 2012. [DOI: 10.1097/00001756-201207110-00007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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302
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Abstract
Although the overproduction of immunoglobulins by short-lived plasma cells accompanying an immune response links with their apoptosis, how long-lived plasma cells adapt to ensure their longevity in this context is obscure. Here, we show that apoptosis signal-regulating kinase 1 (ASK1) contributes to apoptosis of plasma cells because ASK1 activity was induced during differentiation of short-lived plasma cells, and, when produced by ASK1-deficient mice, these cells survived better than those of control mice. Moreover, antigen-specific long-lived plasma cells generated by immunization accumulated in ASK1-deficient mice, suggesting ASK1 also plays a negative role in survival of long-lived plasma cells. In malignant plasma cells, ASK1 transcription was directly suppressed by B lymphocyte-induced maturation protein-1 (Blimp-1). The expression of ASK1 and Blimp-1 showed an inverse correlation between normal human mature B cells and bone marrow plasma cells from patients with multiple myeloma (MM). Suppression of ASK1 is crucial for cell survival because its enforced expression in MM cells caused apoptosis in vitro and lowered MM load in a xenograft animal model; furthermore, alteration of ASK1 activity affected MM cell survival. Our findings indicate a novel mechanism underlying the regulation of survival in normal and malignant plasma cells by ASK1.
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303
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Inhibition of protein translocation at the endoplasmic reticulum promotes activation of the unfolded protein response. Biochem J 2012; 442:639-48. [PMID: 22145777 PMCID: PMC3286858 DOI: 10.1042/bj20111220] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Selective small-molecule inhibitors represent powerful tools for the dissection of complex biological processes. ESI (eeyarestatin I) is a novel modulator of ER (endoplasmic reticulum) function. In the present study, we show that in addition to acutely inhibiting ERAD (ER-associated degradation), ESI causes production of mislocalized polypeptides that are ubiquitinated and degraded. Unexpectedly, our results suggest that these non-translocated polypeptides promote activation of the UPR (unfolded protein response), and indeed we can recapitulate UPR activation with an alternative and quite distinct inhibitor of ER translocation. These results suggest that the accumulation of non-translocated proteins in the cytosol may represent a novel mechanism that contributes to UPR activation.
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304
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Caito S, Fretham S, Martinez-Finley E, Chakraborty S, Avila D, Chen P, Aschner M. Genome-Wide Analyses of Metal Responsive Genes in Caenorhabditis elegans. Front Genet 2012; 3:52. [PMID: 22514555 PMCID: PMC3322339 DOI: 10.3389/fgene.2012.00052] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 03/20/2012] [Indexed: 11/22/2022] Open
Abstract
Metals are major contaminants that influence human health. Many metals have physiologic roles, but excessive levels can be harmful. Advances in technology have made toxicogenomic analyses possible to characterize the effects of metal exposure on the entire genome. Much of what is known about cellular responses to metals has come from mammalian systems; however the use of non-mammalian species is gaining wider attention. Caenorhabditis elegans is a small round worm whose genome has been fully sequenced and its development from egg to adult is well characterized. It is an attractive model for high throughput screens due to its short lifespan, ease of genetic mutability, low cost, and high homology with humans. Research performed in C. elegans has led to insights in apoptosis, gene expression, and neurodegeneration, all of which can be altered by metal exposure. Additionally, by using worms one can potentially study mechanisms that underline differential responses to metals in nematodes and humans, allowing for identification of novel pathways and therapeutic targets. In this review, toxicogenomic studies performed in C. elegans exposed to various metals will be discussed, highlighting how this non-mammalian system can be utilized to study cellular processes and pathways induced by metals. Recent work focusing on neurodegeneration in Parkinson’s disease will be discussed as an example of the usefulness of genetic screens in C. elegans and the novel findings that can be produced.
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Affiliation(s)
- Samuel Caito
- Division of Clinical Pharmacology and Pediatric Toxicology, Department of Pediatrics, Vanderbilt University Medical Center Nashville, TN, USA
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305
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Prell T, Lautenschläger J, Witte OW, Carri MT, Grosskreutz J. The unfolded protein response in models of human mutant G93A amyotrophic lateral sclerosis. Eur J Neurosci 2012; 35:652-60. [DOI: 10.1111/j.1460-9568.2012.08008.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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306
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Diverse Roles of JNK and MKK Pathways in the Brain. JOURNAL OF SIGNAL TRANSDUCTION 2012; 2012:459265. [PMID: 22496975 PMCID: PMC3307000 DOI: 10.1155/2012/459265] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 11/01/2011] [Indexed: 11/18/2022]
Abstract
The c-Jun NH(2)-terminal protein kinase (JNK) plays important roles in a broad range of physiological processes. JNK is controlled by two upstream regulators, mitogen-activated protein kinase kinase (MKK) 4 and MKK7, which are activated by various MAPKKKs. Studies employing knockout mice have demonstrated that the JNK signaling pathway is involved in diverse phenomena in the brain, regulating brain development and maintenance as well as animal metabolism and behavior. Furthermore, examination of single or combined knockout mice of Jnk1, Jnk2, and Jnk3 has revealed both functional differences and redundancy among JNK1, JNK2, and JNK3. Phenotypic differences between knockouts of MKK4 and MKK7 have also been observed, suggesting that the JNK signaling pathway in the brain has a complex nature and is intricately regulated. This paper summarizes the functional properties of the major JNK signaling components in the developing and adult brain.
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307
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Pratt AJ, Getzoff ED, Perry JJP. Amyotrophic lateral sclerosis: update and new developments. Degener Neurol Neuromuscul Dis 2012; 2012:1-14. [PMID: 23019386 PMCID: PMC3457793 DOI: 10.2147/dnnd.s19803] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common form of motor neuron disease. It is typically characterized by adult-onset degeneration of the upper and lower motor neurons, and is usually fatal within a few years of onset. A subset of ALS patients has an inherited form of the disease, and a few of the known mutant genes identified in familial cases have also been found in sporadic forms of ALS. Precisely how the diverse ALS-linked gene products dictate the course of the disease, resulting in compromised voluntary muscular ability, is not entirely known. This review addresses the major advances that are being made in our understanding of the molecular mechanisms giving rise to the disease, which may eventually translate into new treatment options.
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Affiliation(s)
- Ashley J Pratt
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA,
| | - Elizabeth D Getzoff
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA,
| | - J Jefferson P Perry
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA,
- The School of Biotechnology, Amrita University, Kollam, Kerala 690525, India,
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308
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Hetz C. The unfolded protein response: controlling cell fate decisions under ER stress and beyond. Nat Rev Mol Cell Biol 2012; 13:89-102. [PMID: 22251901 DOI: 10.1038/nrm3270] [Citation(s) in RCA: 2817] [Impact Index Per Article: 234.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protein-folding stress at the endoplasmic reticulum (ER) is a salient feature of specialized secretory cells and is also involved in the pathogenesis of many human diseases. ER stress is buffered by the activation of the unfolded protein response (UPR), a homeostatic signalling network that orchestrates the recovery of ER function, and failure to adapt to ER stress results in apoptosis. Progress in the field has provided insight into the regulatory mechanisms and signalling crosstalk of the three branches of the UPR, which are initiated by the stress sensors protein kinase RNA-like ER kinase (PERK), inositol-requiring protein 1α (IRE1α) and activating transcription factor 6 (ATF6). In addition, novel physiological outcomes of the UPR that are not directly related to protein-folding stress, such as innate immunity, metabolism and cell differentiation, have been revealed.
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Affiliation(s)
- Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, P.O. BOX 70086, Chile.
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309
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Lee KW, Zhao X, Im JY, Grosso H, Jang WH, Chan TW, Sonsalla PK, German DC, Ichijo H, Junn E, Mouradian MM. Apoptosis signal-regulating kinase 1 mediates MPTP toxicity and regulates glial activation. PLoS One 2012; 7:e29935. [PMID: 22253830 PMCID: PMC3254627 DOI: 10.1371/journal.pone.0029935] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 12/07/2011] [Indexed: 11/17/2022] Open
Abstract
Apoptosis signal-regulating kinase 1 (ASK1), a member of the mitogen-activated protein kinase 3 family, is activated by oxidative stress. The death-signaling pathway mediated by ASK1 is inhibited by DJ-1, which is linked to recessively inherited Parkinson's disease (PD). Considering that DJ-1 deficiency exacerbates the toxicity of the mitochondrial complex I inhibitor 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), we sought to investigate the direct role and mechanism of ASK1 in MPTP-induced dopamine neuron toxicity. In the present study, we found that MPTP administration to wild-type mice activates ASK1 in the midbrain. In ASK1 null mice, MPTP-induced motor impairment was less profound, and striatal dopamine content and nigral dopamine neuron counts were relatively preserved compared to wild-type littermates. Further, microglia and astrocyte activation seen in wild-type mice challenged with MPTP was markedly attenuated in ASK⁻/⁻ mice. These data suggest that ASK1 is a key player in MPTP-induced glial activation linking oxidative stress with neuroinflammation, two well recognized pathogenetic factors in PD. These findings demonstrate that ASK1 is an important effector of MPTP-induced toxicity and suggest that inhibiting this kinase is a plausible therapeutic strategy for protecting dopamine neurons in PD.
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Affiliation(s)
- Kang-Woo Lee
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Xin Zhao
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Joo-Young Im
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Hilary Grosso
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Won Hee Jang
- Department of Biochemistry, College of Medicine, Inje University, Busan, Korea
| | - Teresa W. Chan
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Patricia K. Sonsalla
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - Dwight C. German
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Hidenori Ichijo
- Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Eunsung Junn
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
| | - M. Maral Mouradian
- Center for Neurodegenerative and Neuroimmunologic Diseases, Department of Neurology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey, United States of America
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310
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HAYAKAWA R, HAYAKAWA T, TAKEDA K, ICHIJO H. Therapeutic targets in the ASK1-dependent stress signaling pathways. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2012; 88:434-53. [PMID: 23060232 PMCID: PMC3491083 DOI: 10.2183/pjab.88.434] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Accepted: 08/17/2012] [Indexed: 05/25/2023]
Abstract
Apoptosis signal-regulating kinase 1 (ASK1) is a member of the mitogen-activated protein kinase kinase kinase (MAP3K) family that activates downstream MAP kinases (MAPKs), c-Jun N-terminal kinases (JNKs) and p38 MAPKs, in response to various stresses, such as reactive oxygen species (ROS), endoplasmic reticulum (ER) stress, lipopolysaccharide, and calcium overload. Activation of the JNK and p38 pathways induces stress responses such as cell death, differentiation, and the production of inflammatory cytokines. A series of studies using ASK1-deficient mice have indicated that ASK1 plays important roles in many stress-related diseases, including cardiovascular and neurodegenerative diseases, suggesting that small compounds that inhibit ASK1 activity could possibly be used for the amelioration of the development and/or progression of these diseases. In this review, we provide an overview of the pathophysiological roles of ASK1-dependent signaling pathways and discuss the mechanistic basis for how these could serve as potential therapeutic targets.
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Affiliation(s)
- Ryoichi HAYAKAWA
- Laboratory of Cell Signaling, Graduate School of
Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Teruyuki HAYAKAWA
- Laboratory of Cell Signaling, Graduate School of
Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Kohsuke TAKEDA
- Laboratory of Cell Signaling, Graduate School of
Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
- Division of Cell Regulation, Graduate School of Biomedical
Sciences, Nagasaki University, Nagasaki, Japan
| | - Hidenori ICHIJO
- Laboratory of Cell Signaling, Graduate School of
Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
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311
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Haeri M, Knox BE. Endoplasmic Reticulum Stress and Unfolded Protein Response Pathways: Potential for Treating Age-related Retinal Degeneration. J Ophthalmic Vis Res 2012; 7:45-59. [PMID: 22737387 PMCID: PMC3381108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 12/18/2011] [Indexed: 11/24/2022] Open
Abstract
Accumulation of misfolded proteins in the endoplasmic reticulum (ER) and their aggregation impair normal cellular function and can be toxic, leading to cell death. Prolonged expression of misfolded proteins triggers ER stress, which initiates a cascade of reactions called the unfolded protein response (UPR). Protein misfolding is the basis for a variety of disorders known as ER storage or conformational diseases. There are an increasing number of eye disorders associated with misfolded proteins and pathologic ER responses, including retinitis pigmentosa (RP). Herein we review the basic cellular and molecular biology of UPR with focus on pathways that could be potential targets for treating retinal degenerative diseases.
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Affiliation(s)
- Mohammad Haeri
- Correspondence to: Mohammad Haeri, MD, PhD. Departments of Neuroscience and Physiology and Ophthalmology, SUNY Upstate Medical University, WH3220, Syracuse, NY 13210, USA; Tel: +1 315 464 8148, Fax: +1 315 464 7725; e-mail:
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312
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Molecular motor proteins and amyotrophic lateral sclerosis. Int J Mol Sci 2011; 12:9057-82. [PMID: 22272119 PMCID: PMC3257116 DOI: 10.3390/ijms12129057] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 11/28/2011] [Accepted: 11/30/2011] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder affecting motor neurons in the brain, brainstem and spinal cord, which is characterized by motor dysfunction, muscle dystrophy and progressive paralysis. Both inherited and sporadic forms of ALS share common pathological features, however, the initial trigger of neurodegeneration remains unknown. Motor neurons are uniquely targeted by ubiquitously expressed proteins in ALS but the reason for this selectively vulnerability is unclear. However motor neurons have unique characteristics such as very long axons, large cell bodies and high energetic metabolism, therefore placing high demands on cellular transport processes. Defects in cellular trafficking are now widely reported in ALS, including dysfunction to the molecular motors dynein and kinesin. Abnormalities to dynein in particular are linked to ALS, and defects in dynein-mediated axonal transport processes have been reported as one of the earliest pathologies in transgenic SOD1 mice. Furthermore, dynein is very highly expressed in neurons and neurons are particularly sensitive to dynein dysfunction. Hence, unravelling cellular transport processes mediated by molecular motor proteins may help shed light on motor neuron loss in ALS.
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313
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Chakrabarti A, Chen AW, Varner JD. A review of the mammalian unfolded protein response. Biotechnol Bioeng 2011; 108:2777-93. [PMID: 21809331 PMCID: PMC3193940 DOI: 10.1002/bit.23282] [Citation(s) in RCA: 303] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 06/21/2011] [Accepted: 07/15/2011] [Indexed: 12/14/2022]
Abstract
Proteins requiring post-translational modifications such as N-linked glycosylation are processed in the endoplasmic reticulum (ER). A diverse array of cellular stresses can lead to dysfunction of the ER and ultimately to an imbalance between protein-folding capacity and protein-folding load. Cells monitor protein folding by an inbuilt quality control system involving both the ER and the Golgi apparatus. Unfolded or misfolded proteins are tagged for degradation via ER-associated degradation (ERAD) or sent back through the folding cycle. Continued accumulation of incorrectly folded proteins can also trigger the unfolded protein response (UPR). In mammalian cells, UPR is a complex signaling program mediated by three ER transmembrane receptors: activating transcription factor 6 (ATF6), inositol requiring kinase 1 (IRE1) and double-stranded RNA-activated protein kinase (PKR)-like endoplasmic reticulum kinase (PERK). UPR performs three functions, adaptation, alarm, and apoptosis. During adaptation, the UPR tries to reestablish folding homeostasis by inducing the expression of chaperones that enhance protein folding. Simultaneously, global translation is attenuated to reduce the ER folding load while the degradation rate of unfolded proteins is increased. If these steps fail, the UPR induces a cellular alarm and mitochondrial mediated apoptosis program. UPR malfunctions have been associated with a wide range of disease states including tumor progression, diabetes, as well as immune and inflammatory disorders. This review describes recent advances in understanding the molecular structure of UPR in mammalian cells, its functional role in cellular stress, and its pathophysiology.
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Affiliation(s)
- Anirikh Chakrabarti
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca NY 14853
| | - Aaron W. Chen
- Polymer Science and Engineering, University of Massachusetts Amherst, Amherst MA 01003
| | - Jeffrey D. Varner
- Corresponding author: Jeffrey D. Varner, Assistant Professor, School of Chemical and Biomolecular Engineering, 244 Olin Hall, Cornell University, Ithaca NY, 14853, , Phone: (607) 255 -4258, Fax: (607) 255 -9166
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314
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Bendotti C, Marino M, Cheroni C, Fontana E, Crippa V, Poletti A, De Biasi S. Dysfunction of constitutive and inducible ubiquitin-proteasome system in amyotrophic lateral sclerosis: implication for protein aggregation and immune response. Prog Neurobiol 2011; 97:101-26. [PMID: 22033150 DOI: 10.1016/j.pneurobio.2011.10.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 09/29/2011] [Accepted: 10/11/2011] [Indexed: 12/11/2022]
Abstract
The ubiquitin-proteasome system (UPS) is the major intracellular proteolytic mechanism controlling the degradation of misfolded/abnormal proteins. A common hallmark in amyotrophic lateral sclerosis (ALS) and in other neurodegenerative disorders is the accumulation of misfolded/abnormal proteins into the damaged neurons, leading to the formation of cellular inclusions that are mostly ubiquitin-positive. Although proteolysis is a complex mechanism requiring the participation of different pathways, the abundant accumulation of ubiquitinated proteins strongly suggests an important contribution of UPS to these neuropathological features. The use of cellular and animal models of ALS, particularly those expressing mutant SOD1, the gene mutation most represented in familiar ALS, has provided significant evidence for a role of UPS in protein inclusions formation and motor neuron death. This review will specifically discuss this piece of evidence and provide suggestions of potential strategies for therapeutic intervention. We will also discuss the finding that, unlike the constitutive proteasome subunits, the inducible subunits are overexpressed early during disease progression in SOD1 mice models of ALS. These subunits form the immunoproteasome and generate peptides for the major histocompatibility complex class I molecules, suggesting a role of this system in the immune responses associated with the pathological features of ALS. Since recent discoveries indicate that innate and adaptive immunity may influence the disease process, in this review we will also provide evidence of a possible connection between immune-inflammatory reactions and UPS function, in the attempt to better understand the etiopathology of ALS and to identify appropriate targets for novel treatment strategies of this devastating disease.
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Affiliation(s)
- Caterina Bendotti
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Mario Negri Institute for Pharmacological Research, Via La Masa, 19, 20156 Milano, Italy.
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315
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Ido A, Fukuyama H, Urushitani M. Protein misdirection inside and outside motor neurons in Amyotrophic Lateral Sclerosis (ALS): a possible clue for therapeutic strategies. Int J Mol Sci 2011; 12:6980-7003. [PMID: 22072931 PMCID: PMC3211022 DOI: 10.3390/ijms12106980] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 10/09/2011] [Accepted: 10/11/2011] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by progressive muscle wasting and weakness with no effective cure. Emerging evidence supports the notion that the abnormal conformations of ALS-linked proteins play a central role in triggering the motor neuron degeneration. In particular, mutant types of superoxide dismutase 1 (SOD1) and TAR DNA binding protein 43kDa (TDP-43) are key molecules involved in the pathogenesis of familial and sporadic ALS, respectively. The commonalities of the two proteins include a propensity to aggregate and acquire detrimental conformations through oligomerization, fragmentation, or post-translational modification that may drive abnormal subcellular localizations. Although SOD1 is a major cytosolic protein, mutated SOD1 has been localized to mitochondria, endoplasmic reticulum, and even the extracellular space. The nuclear exclusion of TDP-43 is a pathological hallmark for ALS, although the pathogenic priority remains elusive. Nevertheless, these abnormal behaviors based on the protein misfolding are believed to induce diverse intracellular and extracellular events that may be tightly linked to non-cell-autonomous motor neuron death. The generation of mutant- or misfolded protein-specific antibodies would help to uncover the distribution and propagation of the ALS-linked proteins, and to design a therapeutic strategy to clear such species. Herein we review the literature regarding the mislocalization of ALS-linked proteins, especially mutant SOD1 and TDP-43 species, and discuss the rationale of molecular targeting strategies including immunotherapy.
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Affiliation(s)
- Akemi Ido
- Unit for Neurobiology and Therapeutics, Molecular Neuroscience Research Center, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan; E-Mail:
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan; E-Mail:
| | - Hidenao Fukuyama
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan; E-Mail:
| | - Makoto Urushitani
- Unit for Neurobiology and Therapeutics, Molecular Neuroscience Research Center, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel./Fax: +81-77-548-2328
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316
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Accumulation of wildtype and ALS-linked mutated VAPB impairs activity of the proteasome. PLoS One 2011; 6:e26066. [PMID: 21998752 PMCID: PMC3187839 DOI: 10.1371/journal.pone.0026066] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 09/19/2011] [Indexed: 11/19/2022] Open
Abstract
Cellular homeostasis relies on a tight control of protein synthesis, folding and degradation, in which the endoplasmic reticulum (ER) quality control and the ubiquitin proteasome system (UPS) have an instrumental function. ER stress and aberrant accumulation of misfolded proteins represent a pathological signature of amyotrophic lateral sclerosis (ALS), a fatal paralytic disorder caused by the selective degeneration of motoneurons in the brain and spinal cord. Mutations in the ER-resident protein VAPB have been associated with familial forms of the disease. ALS-linked mutations cause VAPB to form cytoplasmic aggregates. We previously demonstrated that viral-mediated expression of both wildtype and mutant human VAPB (hVAPB) leads to an ER stress response that contributes to the selective death of motoneurons. However, the mechanisms behind ER stress, defective UPS and hVAPB-associated motoneuron degeneration remain elusive. Here, we show that the overexpression of wildtype and mutated hVAPB, which is found to be less stable than the wildtype protein, leads to the abnormal accumulation of ubiquitin and ubiquitin-like protein conjugates in non-human primate cells. We observed that overexpression of both forms of hVAPB elicited an ER stress response. Treatment of wildtype and mutated hVAPB expressing cells with the ER stress inhibitor salubrinal diminished the burden of ubiquitinated proteins, suggesting that ER stress contributes to the impairment of proteasome function. We also found that both wildtype and mutated hVAPB can associate with the 20S proteasome, which was found to accumulate at the ER with wildtype hVAPB or in mutant hVAPB aggregates. Our results suggest that ER stress and corruption of the proteasome function might contribute to the aberrant protein homeostasis associated with hVAPB.
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317
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Bosco DA, LaVoie MJ, Petsko GA, Ringe D. Proteostasis and movement disorders: Parkinson's disease and amyotrophic lateral sclerosis. Cold Spring Harb Perspect Biol 2011; 3:a007500. [PMID: 21844169 DOI: 10.1101/cshperspect.a007500] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Parkinson's disease (PD) is a movement disorder that afflicts over one million in the U.S.; amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) is less prevalent but also has a high incidence. The two disorders sometimes present together, making a comparative study of interest. Both ALS and PD are neurodegenerative diseases, and are characterized by the presence of intraneuronal inclusions; however, different classes of neurons are affected and the primary protein in the inclusions differs between the diseases, and in some cases is different in distinct forms of the same disease. These observations might suggest that the more general approach of proteostasis pathway alteration would be a powerful one in treating these disorders. Examining results from human genetics and studies in model organisms, as well as from biochemical and biophysical characterization of the proteins involved in both diseases, we find that most instances of PD can be considered as arising from the misfolding, and self-association to a toxic species, of the small neuronal protein α-synuclein, and that proteostasis strategies are likely to be of value for this disorder. For ALS, the situation is much more complex and less clear-cut; the available data are most consistent with a view that ALS may actually be a family of disorders, presenting similarly but arising from distinct and nonoverlapping causes, including mislocalization of some properly folded proteins and derangement of RNA quality control pathways. Applying proteostasis approaches to this disease may require rethinking or broadening the concept of what proteostasis means.
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Affiliation(s)
- Daryl A Bosco
- Department of Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts 01655, USA
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318
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Doyle KM, Kennedy D, Gorman AM, Gupta S, Healy SJM, Samali A. Unfolded proteins and endoplasmic reticulum stress in neurodegenerative disorders. J Cell Mol Med 2011; 15:2025-39. [PMID: 21722302 PMCID: PMC4394214 DOI: 10.1111/j.1582-4934.2011.01374.x] [Citation(s) in RCA: 243] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 06/16/2011] [Indexed: 12/11/2022] Open
Abstract
The stimuli for neuronal cell death in neurodegenerative disorders are multi-factorial and may include genetic predisposition, environmental factors, cellular stressors such as oxidative stress and free radical production, bioenergy failure, glutamate-induced excitotoxicity, neuroinflammation, disruption of Ca(2+) -regulating systems, mitochondrial dysfunction and misfolded protein accumulation. Cellular stress disrupts functioning of the endoplasmic reticulum (ER), a critical organelle for protein quality control, leading to induction of the unfolded protein response (UPR). ER stress may contribute to neurodegeneration in a range of neurodegenerative disorders. This review summarizes the molecular events occurring during ER stress and the unfolded protein response and it specifically evaluates the evidence suggesting the ER stress response plays a role in neurodegenerative disorders.
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Affiliation(s)
| | - Donna Kennedy
- School of Natural Sciences, NUI GalwayGalway, Ireland
- Apoptosis Research Center, NUI GalwayGalway, Ireland
| | - Adrienne M Gorman
- School of Natural Sciences, NUI GalwayGalway, Ireland
- Apoptosis Research Center, NUI GalwayGalway, Ireland
| | - Sanjeev Gupta
- School of Medicine, NUI GalwayGalway, Ireland
- Apoptosis Research Center, NUI GalwayGalway, Ireland
| | - Sandra J M Healy
- School of Natural Sciences, NUI GalwayGalway, Ireland
- Apoptosis Research Center, NUI GalwayGalway, Ireland
| | - Afshin Samali
- School of Medicine, NUI GalwayGalway, Ireland
- School of Natural Sciences, NUI GalwayGalway, Ireland
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319
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The KDEL receptor induces autophagy to promote the clearance of neurodegenerative disease-related proteins. Neuroscience 2011; 190:43-55. [DOI: 10.1016/j.neuroscience.2011.06.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 05/10/2011] [Accepted: 06/01/2011] [Indexed: 12/14/2022]
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320
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Walker AK, Atkin JD. Stress signaling from the endoplasmic reticulum: A central player in the pathogenesis of amyotrophic lateral sclerosis. IUBMB Life 2011; 63:754-63. [PMID: 21834058 DOI: 10.1002/iub.520] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 05/24/2011] [Indexed: 12/15/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterized by the misfolding and aggregation of distinct proteins in affected tissues, however, the pathogenic cause of disease remains unknown. Recent evidence indicates that endoplasmic reticulum (ER) stress plays a central role in ALS pathogenesis. ER stress activates the unfolded protein response (UPR), a homeostatic response to misfolded proteins. The UPR is initially protective by up-regulation of specific ER stress-regulated genes and inhibition of general protein translation. However, long-term ER stress leads to cell death via apoptotic signaling, thus providing a link to neurodegeneration. Activation of the UPR is one of the earliest events in affected motor neurons of transgenic rodent models expressing ALS-linked mutant superoxide dismutase 1 (SOD1). Recently, genetic manipulation of ER stress in several different SOD1 mouse models was shown to alter disease onset and progression, implicating an active role for the UPR in disease mechanisms. Furthermore, mutations to vesicle-associated membrane protein-associated protein B (VAPB), an ER transmembrane protein involved in ER stress regulation, also cause some cases of familial ALS. ER stress also occurs in spinal cord tissues of human sporadic ALS patients, and recent evidence suggests that perturbation of the ER could occur in ALS cases associated with TAR DNA binding protein 43 (TDP-43), fused in sarcoma (FUS) and valosin containing protein (VCP). Together these findings implicate ER stress as a potential upstream mechanism involved in both familial and sporadic forms of ALS.
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Affiliation(s)
- Adam K Walker
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, VIC, Australia
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321
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Abstract
INTRODUCTION Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disease that results in increasing disability and that is uniformly fatal. Since its approval in the 1990s, riluzole remains the sole treatment for ALS offering modest survival benefit. While significant advances have been made in the symptomatic management of the disease, more effective drug therapy targeting disease progression is sorely needed. AREAS COVERED Advances in the understanding of pathogenic mechanisms involved in disease development and progression have provided multiple avenues for developing effective treatment strategies. This review highlights recent discoveries relating to these diverse mechanisms and their implications for the development of drug therapy. Previous human clinical trials that have targeted these pathways are mentioned and ongoing drug trials are discussed. EXPERT OPINION The search for effective drug therapy faces important challenges in the areas of basic science and animal research, translation of these results into human clinical trials, inherent bias in human studies and issues related to delays in clinical diagnosis. How these issues may be addressed and why ALS research constitutes fertile grounds for drug development not only for this devastating disease, but also for other more prevalent neurodegenerative diseases, is discussed in this review.
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Affiliation(s)
- Ali Aamer Habib
- The Neurological Institute of Columbia University, Eleanor and Lou Gehrig MDA/ALS Center, NY 10032, USA.
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322
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Takeda K, Naguro I, Nishitoh H, Matsuzawa A, Ichijo H. Apoptosis signaling kinases: from stress response to health outcomes. Antioxid Redox Signal 2011; 15:719-61. [PMID: 20969480 DOI: 10.1089/ars.2010.3392] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Apoptosis is a highly regulated process essential for the development and homeostasis of multicellular organisms. Whereas caspases, a large family of intracellular cysteine proteases, play central roles in the execution of apoptosis, other proapoptotic and antiapoptotic regulators such as the members of the Bcl-2 family are also critically involved in the regulation of apoptosis. A large body of evidence has revealed that a number of protein kinases are among such regulators and regulate cellular sensitivity to various proapoptotic signals at multiple steps in apoptosis. However, recent progress in the analysis of these apoptosis signaling kinases demonstrates that they generally act as crucial regulators of diverse cellular responses to a wide variety of stressors, beyond their roles in apoptosis regulation. In this review, we have cataloged apoptosis signaling kinases involved in cellular stress responses on the basis of their ability to induce apoptosis and discuss their roles in stress responses with particular emphasis on health outcomes upon their dysregulation.
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Affiliation(s)
- Kohsuke Takeda
- Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, Strategic Approach to Drug Discovery and Development in Pharmaceutical Sciences, Global Center of Excellence Program and Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, The University of Tokyo, Tokyo, Japan.
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323
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Dang H, Klokk TI, Schaheen B, McLaughlin BM, Thomas AJ, Durns TA, Bitler BG, Sandvig K, Fares H. Derlin-dependent retrograde transport from endosomes to the Golgi apparatus. Traffic 2011; 12:1417-31. [PMID: 21722281 DOI: 10.1111/j.1600-0854.2011.01243.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Cells have to maintain stable plasma membrane protein and lipid compositions under normal conditions and to remodel their plasma membranes in response to stimuli. This maintenance and remodeling require that integral membrane proteins at the plasma membrane that become misfolded, because of the relatively harsher extracellular milieu or carbohydrate and amino acid sequence changes, are degraded. We had previously shown that Derlin proteins, required for quality control mechanisms in the endoplasmic reticulum, also localize to endosomes and function in the degradation of misfolded integral membrane proteins at the plasma membrane. In this study, we show that Derlin proteins physically associate with sorting nexins that function in retrograde membrane transport from endosomes to the Golgi apparatus. Using genetic studies in Caenorhabditis elegans and ricin pulse-chase analyses in murine RAW264.7 macrophages, we show that the Derlin-sorting nexin interaction is physiologically relevant. Our studies suggest that at least some integral membrane proteins that are misfolded at the plasma membrane are retrogradely transported to the Golgi apparatus and ultimately to the endoplasmic reticulum for degradation via resident quality control mechanisms.
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Affiliation(s)
- Hope Dang
- Department of Molecular and Cellular Biology, Life Sciences South Room 531, University of Arizona, Tucson, AZ 85721, USA
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324
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Riboldi G, Nizzardo M, Simone C, Falcone M, Bresolin N, Comi GP, Corti S. ALS genetic modifiers that increase survival of SOD1 mice and are suitable for therapeutic development. Prog Neurobiol 2011; 95:133-48. [PMID: 21816207 DOI: 10.1016/j.pneurobio.2011.07.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 07/19/2011] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a frequently fatal motor neuron disease without any cure. To find molecular therapeutic targets, several studies crossed transgenic ALS murine models with animals transgenic for some ALS target genes. We aimed to revise the new discoveries and new works in this field. We selected the 10 most promising genes, according to their capability when down-regulated or up-regulated in ALS animal models, for increasing life span and mitigating disease progression: XBP-1, NogoA and NogoB, dynein, heavy and medium neurofilament, NOX1 and NOX2, MLC-mIGF-1, NSE-VEGF, and MMP-9. Interestingly, some crucial modifier genes have been described as being involved in common pathways, the most significant of which are inflammation and cytoskeletal activities. The endoplasmic reticulum also seems to play an important role in ALS pathogenesis, as it is involved in different selected gene pathways. In addition, these genes have evident links to each other, introducing the hypothesis of a single unknown, common pathway involving all of these identified genes and others to be discovered.
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Affiliation(s)
- Giulietta Riboldi
- Department of Neurological Sciences, Dino Ferrari Centre, University of Milan, IRCCS Fondazione Ca' Granda-Ospedale Maggiore Policlinico, Milan, Italy
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325
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Nery FC, Armata IA, Farley JE, Cho JA, Yaqub U, Chen P, da Hora CC, Wang Q, Tagaya M, Klein C, Tannous B, Caldwell KA, Caldwell GA, Lencer WI, Ye Y, Breakefield XO. TorsinA participates in endoplasmic reticulum-associated degradation. Nat Commun 2011; 2:393. [PMID: 21750546 PMCID: PMC3529909 DOI: 10.1038/ncomms1383] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 06/08/2011] [Indexed: 11/09/2022] Open
Abstract
TorsinA is an AAA+ ATPase located within the lumen of the endoplasmic reticulum and nuclear envelope, with a mutant form causing early onset torsion dystonia (DYT1). Here we report a new function for torsinA in endoplasmic reticulum-associated degradation (ERAD). Retro-translocation and proteosomal degradation of a mutant cystic fibrosis transmembrane conductance regulator (CFTRΔF508) was inhibited by downregulation of torsinA or overexpression of mutant torsinA, and facilitated by increased torsinA. Retro-translocation of cholera toxin was also decreased by downregulation of torsinA. TorsinA associates with proteins implicated in ERAD, including Derlin-1, VIMP, and p97. Further, torsinA reduces endoplasmic reticulum stress in nematodes overexpressing CFTRΔF508, and fibroblasts from DYT1 dystonia patients are more sensitive than controls to endoplasmic reticulum stress and less able to degrade mutant CFTR. Therefore, compromised ERAD function in the cells of DYT1 patients may increase sensitivity to endoplasmic reticulum stress with consequent alterations in neuronal function contributing to the disease state.
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Affiliation(s)
- Flávia C Nery
- 1] Neuroscience Center, Department of Neurology, and Center for Molecular Imaging Research, Department of Radiology, Massachusetts General Hospital and Program in Neuroscience, Harvard Medical School, Boston, Massachusetts 02114, USA. [2]
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326
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Honjo Y, Kaneko S, Ito H, Horibe T, Nagashima M, Nakamura M, Fujita K, Takahashi R, Kusaka H, Kawakami K. Protein disulfide isomerase-immunopositive inclusions in patients with amyotrophic lateral sclerosis. ACTA ACUST UNITED AC 2011; 12:444-50. [PMID: 21745122 DOI: 10.3109/17482968.2011.594055] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The major pathological hallmarks of amyotrophic lateral sclerosis (ALS) are neuronal cytoplasmic inclusions (NCIs) and swollen neurites. Superoxide dismutase (SOD)-1-immunopositive NCIs are observed in patients with familial ALS (FALS), and TAR DNA-binding protein 43kDa (TDP-43)-immunopositive NCIs are found in patients with sporadic ALS (SALS). Protein disulfide isomerase (PDI) is a member of the thioredoxin superfamily and is believed to accelerate the folding of disulfide-bonded proteins by catalyzing the disulfide interchange reaction, which is the rate-limiting step during protein folding in the luminal space of the endoplasmic reticulum. Post mortem spinal cord specimens from five patients with SALS and one with FALS (I113T), and five normal controls were utilized in this immunohistochemical study. We found PDI-immunopositive swollen neurites and NCIs in the patients with ALS. Furthermore, PDI was colocalized with TDP-43 and SOD1 in NCIs. The accumulation of misfolding proteins may disturb axon transport and make swollen neurites. As the motor neuron is the longest cell in the nervous system, the motor system may selectively be disturbed. In conclusion, we assume that PDI is S-nitrosylated in the affected neurons, which inhibits its enzymatic activity and thus allows protein misfolding to occur in ALS.
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Affiliation(s)
- Yasuyuki Honjo
- Department of Pharmacoepidemiology, Graduate School of Medicine and Public Health, Kyoto University, Japan
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327
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Gotoh T, Endo M, Oike Y. Endoplasmic reticulum stress-related inflammation and cardiovascular diseases. Int J Inflam 2011; 2011:259462. [PMID: 21755026 PMCID: PMC3132612 DOI: 10.4061/2011/259462] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Accepted: 05/03/2011] [Indexed: 12/21/2022] Open
Abstract
The endoplasmic reticulum (ER) is the site of synthesis and maturation of proteins designed for secretion or for localization on the cell membrane. Various types of stress from both inside and outside cells disturb ER function, thus causing unfolded or misfolded proteins to accumulate in the ER. To improve and maintain the ER functions against such stresses, the ER stress response pathway is activated. However, when the stress is prolonged or severe, apoptosis pathways are activated to remove damaged cells. It was recently reported that the ER stress pathway is also involved in the inflammatory response, whereby inflammation induces ER stress, and ER stress induces an inflammatory response. Therefore, the ER stress response pathway is involved in various diseases, including cardiovascular diseases such as atherosclerosis and ischemic diseases, in various ways. The ER stress pathway may represent a novel target for the treatment of these diseases.
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Affiliation(s)
- Tomomi Gotoh
- Department of Molecular Genetics, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto 860-8556, Japan
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328
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Ugolino J, Fang S, Kubisch C, Monteiro MJ. Mutant Atp13a2 proteins involved in parkinsonism are degraded by ER-associated degradation and sensitize cells to ER-stress induced cell death. Hum Mol Genet 2011; 20:3565-77. [PMID: 21665991 DOI: 10.1093/hmg/ddr274] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mutations in ATP13A2 (PARK9) have been linked to juvenile parkinsonism with dementia or Kufor-Rakeb syndrome (KRS). The ATP13A2 gene encodes at least three protein isoforms that arise by alternate splicing. A previous study indicated the Atp13a2(Isoform-1) protein is localized to lysosomes, whereas three separate mutations involved in disease cause retention of the protein in the ER. One speculation is that the mutant Atp13a2(Isoform-1) proteins are misfolded and eliminated by the ER-associated degradation pathway (ERAD), which involves the dislocation of proteins from the ER to the cytoplasm for proteasome degradation. We examined whether Atp13a2 proteins are degraded by ERAD and whether the Atp13a2(Isoform-3) protein has similar localization to the Atp13a2(Isoform-1) protein. Through analysis of protein turnover and by disrupting different steps in the ERAD pathway we demonstrate that mutant Atp13a2(Isoform-1) proteins are indeed eliminated by ERAD. Thus, siRNA-mediated knockdown of erasin, a platform for assembly of an ERAD complex, or expression of a dominant negative form of p97/VCP, a protein essential for dislocation of ERAD substrates, or inhibition of the proteasome all slowed degradation of the mutant Atp13a2(Isoform-1) proteins, but not the wild-type Atp13a2(Isoform-1) protein. Immunoprecipitation assays confirmed that the Atp13a2 proteins are ubiquitinated in accord with degradation by ERAD. In contrast to Atp13a2(Isoform-1), we show Atp13a2(Isoform-3) is localized to the ER and rapidly degraded. Lastly, we show Atp13a2 mutants have increased cytotoxicity and predispose cells to ER-stress-induced cell death. These results provide new insight into the properties of wild-type and mutant Atp13a2 proteins involved in KRS.
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Affiliation(s)
- Janet Ugolino
- Biochemistry and Molecular Biology Graduate Program, University of Maryland, Baltimore, 725 West Lombard Street, Baltimore, MD 21201, USA
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329
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Hayashi T, Tsai SY, Mori T, Fujimoto M, Su TP. Targeting ligand-operated chaperone sigma-1 receptors in the treatment of neuropsychiatric disorders. Expert Opin Ther Targets 2011; 15:557-77. [PMID: 21375464 PMCID: PMC3076924 DOI: 10.1517/14728222.2011.560837] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Current drugs for the treatment of psychiatric or neurodegenerative disorders have limitations. Psychotherapeutic drugs such as typical and atypical antipsychotics, tricyclic antidepressants and selective monoamine reuptake inhibitors, aim to normalize the hyper- or hypo-neurotransmission of monoaminergic systems. Despite their contribution to the outcomes of psychiatric patients, these agents often exert severe side effects and require chronic treatments to promote amelioration of symptoms. Drugs available for the treatment of neurodegenerative disorders are severely limited. AREAS COVERED Recent evidence that has shed light on sigma-1 receptor ligands, which may serve as a new class of antidepressants or neuroprotective agents. Sigma-1 receptors are novel ligand-operated molecular chaperones regulating signal transduction, ER stress, cellular redox, cellular survival and synaptogenesis. Selective sigma-1 receptor ligands exert rapid antidepressant-like, anxiolytic, antinociceptive and robust neuroprotective actions in preclinical studies. Recent studies that suggest that reactive oxygen species might play a role as signal integrators downstream of Sig-1Rs are also covered. EXPERT OPINION The advances in sigma receptor research in the last decade have begun to elucidate the intracellular signal cascades upstream and downstream of sigma-1 receptors. The novel ligand-operated properties of the sigma-1 receptor chaperone may enable interventions by which stress-related cellular systems can be pharmacologically controlled.
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Affiliation(s)
- Teruo Hayashi
- National Institute on Drug Abuse, National Institutes of Health-Cellular Stress Signaling Unit, Integrative Neuroscience Branch, Baltimore, MD 21224, USA.
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330
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Mechanisms of neuroprotection by protein disulphide isomerase in amyotrophic lateral sclerosis. Neurol Res Int 2011; 2011:317340. [PMID: 21603027 PMCID: PMC3096316 DOI: 10.1155/2011/317340] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 02/20/2011] [Indexed: 11/18/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease characterised by the progressive loss of motor neurons, leading to paralysis and death within several years of onset. Although protein misfolding is a key feature of ALS, the upstream triggers of disease remain elusive. Recently, endoplasmic reticulum (ER) stress was identified as an early and central feature in ALS disease models as well as in human patient tissues, indicating that ER stress could be an important process in disease pathogenesis. One important chaperone induced by ER stress is protein disulphide isomerase (PDI), which is both upregulated and posttranslationally inhibited by S-nitrosylation in ALS. In this paper, we present evidence from studies of genetics, model organisms, and patient tissues which indicate an active role for PDI and ER stress in ALS disease processes.
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331
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Shore GC, Papa FR, Oakes SA. Signaling cell death from the endoplasmic reticulum stress response. Curr Opin Cell Biol 2011; 23:143-9. [PMID: 21146390 PMCID: PMC3078187 DOI: 10.1016/j.ceb.2010.11.003] [Citation(s) in RCA: 298] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Revised: 11/09/2010] [Accepted: 11/20/2010] [Indexed: 12/13/2022]
Abstract
Inability to meet protein folding demands within the endoplasmic reticulum (ER) activates the unfolded protein response (UPR), a signaling pathway with both adaptive and apoptotic outputs. While some secretory cell types have a remarkable ability to increase protein folding capacity, their upper limits can be reached when pathological conditions overwhelm the fidelity and/or output of the secretory pathway. Irremediable 'ER stress' induces apoptosis and contributes to cell loss in several common human diseases, including type 2 diabetes and neurodegeneration. Researchers have begun to elucidate the molecular switches that determine when ER stress is too great to repair and the signals that are then sent from the UPR to execute the cell.
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Affiliation(s)
- Gordon C. Shore
- Department of Biochemistry and Goodman Cancer Center, McGill University, Montreal, Quebec, H3G 1Y6, Canada
| | - Feroz R. Papa
- Department of Medicine, Diabetes Center, & California Institute for Quantitative Biosciences, University of California-San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA
| | - Scott A. Oakes
- Department of Pathology, University of California-San Francisco, 513 Parnassus Avenue, San Francisco, CA 94143, USA
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332
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Volynets GP, Chekanov MO, Synyugin AR, Golub AG, Kukharenko OP, Bdzhola VG, Yarmoluk SM. Identification of 3H-naphtho[1,2,3-de]quinoline-2,7-diones as inhibitors of apoptosis signal-regulating kinase 1 (ASK1). J Med Chem 2011; 54:2680-6. [PMID: 21449566 DOI: 10.1021/jm200117h] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Apoptosis signal-regulating kinase 1 (ASK1) has recently emerged as an attractive therapeutic target for the treatment of cardiac and neurodegenerative disorders. The selective inhibitors of ASK1 may become important compounds for the development of clinical agents. We have identified the ASK1 inhibitor among 3H-naphtho[1,2,3-de]quinoline-2,7-diones using receptor-based virtual screening. In vitro kinase assay revealed that ethyl 2,7-dioxo-2,7-dihydro-3H-naphtho[1,2,3-de]quinoline-1-carboxylate (NQDI-1) inhibited ASK1 with a K(i) of 500 nM. The competitive character of inhibition is demonstrated in Lineweaver-Burk plots. In our preliminary selectivity study this compound exhibited strong specific inhibitory activity toward ASK1.
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Affiliation(s)
- Galyna P Volynets
- Institute of Molecular Biology and Genetics, NAS of Ukraine, Kyiv, Ukraine
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333
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Guo X, Harada C, Namekata K, Matsuzawa A, Camps M, Ji H, Swinnen D, Jorand-Lebrun C, Muzerelle M, Vitte PA, Rückle T, Kimura A, Kohyama K, Matsumoto Y, Ichijo H, Harada T. Regulation of the severity of neuroinflammation and demyelination by TLR-ASK1-p38 pathway. EMBO Mol Med 2011; 2:504-15. [PMID: 21064192 PMCID: PMC3377347 DOI: 10.1002/emmm.201000103] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Apoptosis signal-regulating kinase 1 (ASK1) is an evolutionarily conserved mitogen-activated protein kinase (MAPK) kinase kinase which plays important roles in stress and immune responses. Here, we show that ASK1 deficiency attenuates neuroinflammation in experimental autoimmune encephalomyelitis (EAE), without affecting the proliferation capability of T cells. Moreover, we found that EAE upregulates expression of Toll-like receptors (TLRs) in activated astrocytes and microglia, and that TLRs can synergize with ASK1-p38 MAPK signalling in the release of key chemokines from astrocytes. Consequently, oral treatment with a specific small molecular weight inhibitor of ASK1 suppressed EAE-induced autoimmune inflammation in both spinal cords and optic nerves. These results suggest that the TLR-ASK1-p38 pathway in glial cells may serve as a valid therapeutic target for autoimmune demyelinating disorders including multiple sclerosis.
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Affiliation(s)
- Xiaoli Guo
- Department of Molecular Neurobiology, Tokyo Metropolitan Institute for Neuroscience, Tokyo Metropolitan Organization for Medical Research, Fuchu, Tokyo, Japan
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334
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Matus S, Glimcher LH, Hetz C. Protein folding stress in neurodegenerative diseases: a glimpse into the ER. Curr Opin Cell Biol 2011; 23:239-52. [PMID: 21288706 DOI: 10.1016/j.ceb.2011.01.003] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 01/05/2011] [Accepted: 01/11/2011] [Indexed: 01/19/2023]
Abstract
Several neurodegenerative diseases share common neuropathology, primarily featuring the presence in the brain of abnormal protein inclusions containing specific misfolded proteins. Recent evidence indicates that alteration in organelle function is a common pathological feature of protein misfolding disorders, highlighting perturbations in the homeostasis of the endoplasmic reticulum (ER). Signs of ER stress have been detected in most experimental models of neurological disorders and more recently in brain samples from human patients with neurodegenerative disease. To cope with ER stress, cells activate an integrated signaling response termed the unfolded protein response (UPR), which aims to reestablish homeostasis in part through regulation of genes involved in protein folding, quality control and degradation pathways. Here we discuss the particular mechanisms currently proposed to be involved in the generation of protein folding stress in different neurodegenerative conditions and speculate about possible therapeutic interventions.
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Affiliation(s)
- Soledad Matus
- Center for Molecular Studies of Cell, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile
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335
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Abstract
Although often considered as a group, spinal motor neurons are highly diverse in terms of their morphology, connectivity, and functional properties and differ significantly in their response to disease. Recent studies of motor neuron diversity have clarified developmental mechanisms and provided novel insights into neurodegeneration in amyotrophic lateral sclerosis (ALS). Motor neurons of different classes and subtypes--fast/slow, alpha/gamma--are grouped together into motor pools, each of which innervates a single skeletal muscle. Distinct mechanisms regulate their development. For example, glial cell line-derived neurotrophic factor (GDNF) has effects that are pool-specific on motor neuron connectivity, column-specific on axonal growth, and subtype-specific on survival. In multiple degenerative contexts including ALS, spinal muscular atrophy (SMA), and aging, fast-fatigable (FF) motor units degenerate early, whereas motor neurons innervating slow muscles and those involved in eye movement and pelvic sphincter control are strikingly preserved. Extrinsic and intrinsic mechanisms that confer resistance represent promising therapeutic targets in these currently incurable diseases.
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Affiliation(s)
- Kevin C Kanning
- Department of Pathology, Center for Motor Neuron Biology and Disease, Columbia University Medical Center, New York, NY 10032, USA
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336
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Oslowski CM, Urano F. Measuring ER stress and the unfolded protein response using mammalian tissue culture system. Methods Enzymol 2011; 490:71-92. [PMID: 21266244 DOI: 10.1016/b978-0-12-385114-7.00004-0] [Citation(s) in RCA: 629] [Impact Index Per Article: 48.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The endoplasmic reticulum (ER) functions to properly fold and process secreted and transmembrane proteins. Environmental and genetic factors that disrupt ER function cause an accumulation of misfolded and unfolded proteins in the ER lumen, a condition termed ER stress. ER stress activates a signaling network called the Unfolded Protein Response (UPR) to alleviate this stress and restore ER homeostasis, promoting cell survival and adaptation. However, under unresolvable ER stress conditions, the UPR promotes apoptosis. Here, we discuss the current methods to measure ER stress levels, UPR activation, and subsequent pathways in mammalian cells. These methods will assist us in understanding the UPR and its contribution to ER stress-related disorders such as diabetes and neurodegeneration.
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Affiliation(s)
- Christine M Oslowski
- Program in Gene Function and Expression, University of Massachusetts, Medical School, Worcester, Massachusetts, USA
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337
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Derlin-1 overexpression ameliorates mutant SOD1-induced endoplasmic reticulum stress by reducing mutant SOD1 accumulation. Neurochem Int 2010; 58:344-53. [PMID: 21185345 DOI: 10.1016/j.neuint.2010.12.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 12/08/2010] [Accepted: 12/09/2010] [Indexed: 11/22/2022]
Abstract
Unfolded protein responses, including induction of stress sensor kinases, chaperones, and apoptotic mediators, are involved in the familial amyotrophic lateral sclerosis (ALS) model related to mutant Cu/Zn superoxide dismutase (SOD1) and sporadic ALS. We hypothesized that the endoplasmic reticulum-resident factor Derlin-1 plays a pivotal role in the regulation of misfolded proteins evoked by mutant SOD1. We show that Derlin-1 overexpression reduced mutant SOD1-induced cell toxicity and increased cell viability by suppressing the activation of the ER stress pathway factors: immunoglobulin-binding protein, activating transcription factor 6 p50, and C/EBP homologous protein. Interestingly, exogenous Derlin-1 resulted in a decrease in the amount of mutant SOD1, and a lesser decrease in that of wild-type SOD1, in transfected cells. Reduced SOD1 protein expression was observed in the microsomal fraction of wild-type and mutant SOD1 cells. Our results indicate that Derlin-1 regulates the turn over of SOD1 by promoting the proteasomal and autophagosomal degradation of SOD1 protein, but not by decreasing mutant SOD1 mRNA levels. Insights into the effects of Derlin-1 on mutant SOD1 may facilitate advancements in the treatment of motor neuron degeneration associated with ALS.
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338
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Wang L, Popko B, Roos RP. The unfolded protein response in familial amyotrophic lateral sclerosis. Hum Mol Genet 2010; 20:1008-15. [PMID: 21159797 DOI: 10.1093/hmg/ddq546] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mutant superoxide dismutase type 1 (MTSOD1) is thought to cause ∼20% of cases of familial amyotrophic lateral sclerosis (FALS) because it misfolds and aggregates. Previous studies have shown that MTSOD1 accumulates inside the endoplasmic reticulum (ER) and activates the unfolded protein response (UPR), suggesting that ER stress is involved in the pathogenesis of FALS. We used a genetic approach to investigate the role of the UPR in FALS. We crossed G85RSOD1 transgenic mice with pancreatic ER kinase haploinsufficient (PERK(+/-)) mice to obtain G85R/PERK(+/-) mice. PERK(+/-) mice carry a loss of function mutation of PERK, which is the most rapidly activated UPR pathway, but have no abnormal phenotype. Compared with G85R transgenic mice, G85R/PERK(+/-) mice had a dramatically accelerated disease onset as well as shortened disease duration and lifespan. There was also acceleration of the pathology and earlier MTSOD1 aggregation. A diminished PERK response accelerated disease and pathology in G85R transgenic mice presumably because the mice had a reduced capacity to turn down synthesis of misfolded SOD1, leading to an early overloading of the UPR. The results indicate that the UPR has a significant influence on FALS, and suggest that enhancing the UPR may be effective in treating ALS.
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Affiliation(s)
- Lijun Wang
- Department of Neurology/MC2030, The University of Chicago Pritzker School of Medicine, 5841 S. Maryland Avenue, Chicago, IL 60637, USA
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339
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Nassif M, Matus S, Castillo K, Hetz C. Amyotrophic lateral sclerosis pathogenesis: a journey through the secretory pathway. Antioxid Redox Signal 2010; 13:1955-89. [PMID: 20560784 DOI: 10.1089/ars.2009.2991] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is the most common adult-onset motoneuron degenerative disease characterized by the selective loss of motoneurons in the spinal ventral horn, most brainstem nuclei, and the cerebral cortex. Although approximately 90% of ALS cases are sporadic (sALS), analyses of familial ALS (fALS)-causative genes have generated relevant insight into molecular events involved in the pathology. Here we overview an emerging concept indicating the occurrence of secretory pathway stress in the disease process. These alterations include a failure in the protein folding machinery at the endoplasmic reticulum (ER), engagement of the unfolded protein response (UPR), modifications of the Golgi apparatus network, impaired vesicular trafficking, inhibition of protein quality control mechanisms, oxidative damage to ER proteins, and sustained activation of degradative pathways such as autophagy. A common feature predicted for most of these alterations is abnormal protein homeostasis associated with the accumulation of misfolded proteins at the ER, possibly leading to chronic ER stress and neuronal dysfunction. Signs of ER stress are observed even during presymptomatic stages in fALS mouse models, and pharmacological strategies to alleviate protein misfolding slow disease progression. Because the secretory pathway stress occurs in both sALS and several forms of fALS, it may offer a unique common target for possible therapeutic strategies to treat this devastating disease.
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Affiliation(s)
- Melissa Nassif
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences , Faculty of Medicine, NEMO Millennium Nucleus, Santiago, Chile
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340
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Tovar-y-Romo LB, Tapia R. VEGF protects spinal motor neurons against chronic excitotoxic degeneration in vivo by activation of PI3-K pathway and inhibition of p38MAPK. J Neurochem 2010; 115:1090-101. [DOI: 10.1111/j.1471-4159.2010.06766.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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341
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ASK1 Overexpression Accelerates Paraquat-Induced Autophagy via Endoplasmic Reticulum Stress. Toxicol Sci 2010; 119:156-68. [DOI: 10.1093/toxsci/kfq313] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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342
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Hedlund E, Karlsson M, Osborn T, Ludwig W, Isacson O. Global gene expression profiling of somatic motor neuron populations with different vulnerability identify molecules and pathways of degeneration and protection. ACTA ACUST UNITED AC 2010; 133:2313-30. [PMID: 20826431 DOI: 10.1093/brain/awq167] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Different somatic motor neuron subpopulations show a differential vulnerability to degeneration in diseases such as amyotrophic lateral sclerosis, spinal muscular atrophy and spinobulbar muscular atrophy. Studies in mutant superoxide dismutase 1 over-expressing amyotrophic lateral sclerosis model mice indicate that initiation of disease is intrinsic to motor neurons, while progression is promoted by astrocytes and microglia. Therefore, analysis of the normal transcriptional profile of motor neurons displaying differential vulnerability to degeneration in motor neuron disease could give important clues to the mechanisms of relative vulnerability. Global gene expression profiling of motor neurons isolated by laser capture microdissection from three anatomical nuclei of the normal rat, oculomotor/trochlear (cranial nerve 3/4), hypoglossal (cranial nerve 12) and lateral motor column of the cervical spinal cord, displaying differential vulnerability to degeneration in motor neuron disorders, identified enriched transcripts for each neuronal subpopulation. There were striking differences in the regulation of genes involved in endoplasmatic reticulum and mitochondrial function, ubiquitination, apoptosis regulation, nitrogen metabolism, calcium regulation, transport, growth and RNA processing; cellular pathways that have been implicated in motor neuron diseases. Confirmation of genes of immediate biological interest identified differential localization of insulin-like growth factor II, guanine deaminase, peripherin, early growth response 1, soluble guanylate cyclase 1A3 and placental growth factor protein. Furthermore, the cranial nerve 3/4-restricted genes insulin-like growth factor II and guanine deaminase protected spinal motor neurons from glutamate-induced toxicity (P < 0.001, ANOVA), indicating that our approach can identify factors that protect or make neurons more susceptible to degeneration.
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Affiliation(s)
- Eva Hedlund
- Center for Neuroregeneration Research, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA.
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343
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Abstract
β-Cell death is an important pathogenic component of both type 1 and type 2 diabetes. Recent findings indicate that cell signalling pathways emanating from the endoplasmic reticulum (ER) play an important role in the regulation of β-cell death during the progression of diabetes. Homeostasis within the ER must be maintained to produce properly folded secretory proteins, such as insulin, in response to the body's need for them. However, the sensitive protein-folding environment in the ER can be perturbed by genetic and environmental factors leading to ER stress. To counteract ER stress, β-cells activate cell signalling pathways termed the unfolded protein response (UPR). The UPR functions as a binary switch between life and death, regulating both survival and death effectors. The outcome of this switch depends on the nature of the ER stress condition, the regulation of UPR activation and the expression and activation of survival and death components. This review discusses the mechanisms and the components in this switch and highlights the roles of this UPR's balancing act between life and death in β-cells.
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Affiliation(s)
- Christine M. Oslowski
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, MA 01605, U.S.A
| | - Fumihiko Urano
- Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, MA 01605, U.S.A
- Program in Molecular Medicine University of Massachusetts Medical School, Worcester, MA 01605, U.S.A
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344
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Misfolded mutant SOD1 directly inhibits VDAC1 conductance in a mouse model of inherited ALS. Neuron 2010; 67:575-87. [PMID: 20797535 DOI: 10.1016/j.neuron.2010.07.019] [Citation(s) in RCA: 235] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2010] [Indexed: 02/07/2023]
Abstract
Mutations in superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS), a neurodegenerative disease characterized by loss of motor neurons. With conformation-specific antibodies, we now demonstrate that misfolded mutant SOD1 binds directly to the voltage-dependent anion channel (VDAC1), an integral membrane protein imbedded in the outer mitochondrial membrane. This interaction is found on isolated spinal cord mitochondria and can be reconstituted with purified components in vitro. ADP passage through the outer membrane is diminished in spinal mitochondria from mutant SOD1-expressing ALS rats. Direct binding of mutant SOD1 to VDAC1 inhibits conductance of individual channels when reconstituted in a lipid bilayer. Reduction of VDAC1 activity with targeted gene disruption is shown to diminish survival by accelerating onset of fatal paralysis in mice expressing the ALS-causing mutation SOD1(G37R). Taken together, our results establish a direct link between misfolded mutant SOD1 and mitochondrial dysfunction in this form of inherited ALS.
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345
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Cheung VG, Nayak RR, Wang IX, Elwyn S, Cousins SM, Morley M, Spielman RS. Polymorphic cis- and trans-regulation of human gene expression. PLoS Biol 2010; 8. [PMID: 20856902 PMCID: PMC2939022 DOI: 10.1371/journal.pbio.1000480] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 08/03/2010] [Indexed: 12/11/2022] Open
Abstract
Using genetic and molecular analyses, we identified over 1,000 polymorphic regulators that regulate expression levels of human genes. Expression levels of human genes vary extensively among individuals. This variation facilitates analyses of expression levels as quantitative phenotypes in genetic studies where the entire genome can be scanned for regulators without prior knowledge of the regulatory mechanisms, thus enabling the identification of unknown regulatory relationships. Here, we carried out such genetic analyses with a large sample size and identified cis- and trans-acting polymorphic regulators for about 1,000 human genes. We validated the cis-acting regulators by demonstrating differential allelic expression with sequencing of transcriptomes (RNA-Seq) and the trans-regulators by gene knockdown, metabolic assays, and chromosome conformation capture analysis. The majority of the regulators act in trans to the target (regulated) genes. Most of these trans-regulators were not known to play a role in gene expression regulation. The identification of these regulators enabled the characterization of polymorphic regulation of human gene expression at a resolution that was unattainable in the past. Cellular characteristics and functions are determined largely by gene expression and expression levels differ among individuals, however it is not clear how these levels are regulated. While many cis-acting DNA sequence variants in promoters and enhancers that influence gene expression have been identified, only a few polymorphic trans-regulators of human genes are known. Here, we used human B-cells from individuals belonging to large families and identified polymorphic trans-regulators for about 1,000 human genes. We validated these results by gene knockdown, metabolic perturbation studies and chromosome conformation capture assays. Although these regulatory relationships were identified in cultured B-cells, we show that some of the relationships were also found in primary fibroblasts. The large number of regulators allowed us to better understand gene expression regulation, to uncover new gene functions, and to identify their roles in disease processes. This study shows that genetic variation is a powerful tool not only for gene mapping but also to study gene interaction and regulation.
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Affiliation(s)
- Vivian G Cheung
- Howard Hughes Medical Institute, Philadelphia, Pennsylvania, USA.
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346
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Mehnert M, Sommer T, Jarosch E. ERAD ubiquitin ligases: multifunctional tools for protein quality control and waste disposal in the endoplasmic reticulum. Bioessays 2010; 32:905-13. [PMID: 20806269 DOI: 10.1002/bies.201000046] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In eukaryotic cells terminally misfolded proteins of the secretory pathway are retarded in the endoplasmic reticulum (ER) and subsequently degraded in a ubiquitin-proteasome-dependent manner. This highly conserved process termed ER-associated protein degradation (ERAD) ensures homeostasis in the secretory pathway by disposing faulty polypeptides and preventing their deleterious accumulation and eventual aggregation in the cell. The focus of this paper is the functional description of membrane-bound ubiquitin ligases, which are involved in all critical steps of ERAD. In the end we want to speculate on how the modular architecture of these entities ensures the specificity of substrate selection and possibly accomplishes the transport of misfolded polypeptides from the ER into the cytoplasm.
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Affiliation(s)
- Martin Mehnert
- Max-Delbrück Center for Molecular Medicine, Robert-Rössle-Str., Berlin, Germany
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347
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348
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Osada N, Kosuge Y, Ishige K, Ito Y. Characterization of neuronal and astroglial responses to ER stress in the hippocampal CA1 area in mice following transient forebrain ischemia. Neurochem Int 2010; 57:1-7. [DOI: 10.1016/j.neuint.2010.03.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2010] [Revised: 03/10/2010] [Accepted: 03/24/2010] [Indexed: 01/05/2023]
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349
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Abstract
The lumen of the endoplasmic reticulum constitutes a separate intracellular compartment with a special proteome and metabolome. The redox conditions of the organelle are also characteristically different from those of the other subcellular compartments. The luminal environment has been considered more oxidizing than the cytosol due to the presence of oxidative protein folding. However, recent observations suggest that redox systems in reduced and oxidized states are present simultaneously. The concerted action of membrane transporters and oxidoreductase enzymes maintains the oxidized state of the thiol-disulfide and the reduced state of the pyridine nucleotide redox systems, which are prerequisites for the normal redox reactions localized in the organelle. The powerful thiol-oxidizing machinery of oxidative protein folding continuously challenges the local antioxidant defense. Alterations of the luminal redox conditions, either in oxidizing or reducing direction, affect protein processing, are sensed by the accumulation of misfolded/unfolded proteins, and may induce endoplasmic reticulum stress and unfolded protein response. The activated signaling pathways attempt to restore the balance between protein loading and processing and induce programmed cell death if these attempts fail. Recent findings strongly support the involvement of redox-based endoplasmic reticulum stress in a plethora of human diseases, either as causative agents or as complications.
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Affiliation(s)
- Miklós Csala
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
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350
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Maruyama T, Kadowaki H, Okamoto N, Nagai A, Naguro I, Matsuzawa A, Shibuya H, Tanaka K, Murata S, Takeda K, Nishitoh H, Ichijo H. CHIP-dependent termination of MEKK2 regulates temporal ERK activation required for proper hyperosmotic response. EMBO J 2010; 29:2501-14. [PMID: 20588253 DOI: 10.1038/emboj.2010.141] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 05/31/2010] [Indexed: 11/09/2022] Open
Abstract
The extracellular signal-regulated kinase (ERK) pathway is an important signalling pathway that regulates a large number of cellular processes, including proliferation, differentiation and gene expression. Hyperosmotic stress activates the ERK pathway, whereas little is known about the regulatory mechanisms and physiological functions of ERK activation in hyperosmotic response. Here, we show that MAPK/ERK kinase kinase 2 (MEKK2), a member of the MAPKKK family, mediated the specific and transient activation of ERK, which was required for the induction of aquaporin 1 (AQP1) and AQP5 gene expression in response to hyperosmotic stress. Moreover, we identified the E3 ubiquitin ligase carboxyl terminus of Hsc70-interacting protein (CHIP) as a binding partner of MEKK2. Depletion of CHIP by small-interference RNA or gene targeting attenuated the degradation of MEKK2 and prolonged the ERK activity. Interestingly, hyperosmolality-induced gene expression of AQP1 and AQP5 was suppressed by CHIP depletion and was reversed by inhibition of the prolonged phase of ERK activity. These findings show that transient activation of the ERK pathway, which depends not only on MEKK2 activation, but also on CHIP-dependent MEKK2 degradation, is crucial for proper gene expression in hyperosmotic stress response.
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Affiliation(s)
- Takeshi Maruyama
- Department of Medical Pharmaceutics, Laboratory of Cell Signaling, Japan Science and Technology Corporation, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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