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ARP101, a selective MMP-2 inhibitor, induces autophagy-associated cell death in cancer cells. Biochem Biophys Res Commun 2011; 404:1039-43. [DOI: 10.1016/j.bbrc.2010.12.106] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 12/21/2010] [Indexed: 12/21/2022]
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252
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Abstract
Autophagy is emerging as a central regulator of cellular health and disease and, in the central nervous system (CNS), this homeostatic process appears to influence synaptic growth and plasticity. Herein, we review the evidence that dysregulation of autophagy may contribute to several neurodegenerative diseases of the CNS. Up-regulation of autophagy may prevent, delay or ameliorate at least some of these disorders, and - based on recent findings from our laboratory - we speculate that this goal may be achieved using a safe, simple and inexpensive approach.
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Affiliation(s)
- Mehrdad Alirezaei
- Department of Immunology and Microbial Science, SP30-2110, The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA
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253
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Lee SJ, Desplats P, Sigurdson C, Tsigelny I, Masliah E. Cell-to-cell transmission of non-prion protein aggregates. Nat Rev Neurol 2010; 6:702-6. [PMID: 21045796 PMCID: PMC4996353 DOI: 10.1038/nrneurol.2010.145] [Citation(s) in RCA: 232] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Neurodegenerative disorders such as Alzheimer disease, Parkinson disease, frontotemporal dementia, Huntington disease and Creutzfeldt-Jakob disease (CJD) are characterized by progressive accumulation of protein aggregates in selected brain regions. Protein misfolding and templated assembly into aggregates might result from an imbalance between protein synthesis, aggregation and clearance. Although protein misfolding and aggregation occur in most neurodegenerative disorders, the concept of spreading and infectivity of aggregates in the CNS has, until now, been confined to prion diseases such as CJD and bovine spongiform encephalopathy. Emerging evidence, however, suggests that prion-like spreading, involving secreted proteins such as amyloid-β and cytosolic proteins such as tau, huntingtin and α-synuclein, can occur in other neurodegenerative disorders. The underlying molecular mechanisms and the therapeutic implications of the new data are discussed in this article.
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Affiliation(s)
- Seung-Jae Lee
- Department of Biomedical Science and Technology, IBST, Konkuk University, Seoul 143-701, Korea
| | - Paula Desplats
- Departments of Neurosciences and Pathology, University of California, San Diego, La Jolla, CA, USA
| | - Christina Sigurdson
- Departments of Neurosciences and Pathology, University of California, San Diego, La Jolla, CA, USA
| | - Igor Tsigelny
- Departments of Neurosciences and Pathology, University of California, San Diego, La Jolla, CA, USA
| | - Eliezer Masliah
- Departments of Neurosciences and Pathology, University of California, San Diego, La Jolla, CA, USA
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254
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Cao K, Chen-Plotkin AS, Plotkin JB, Wang LS. Age-correlated gene expression in normal and neurodegenerative human brain tissues. PLoS One 2010; 5. [PMID: 20927326 PMCID: PMC2947518 DOI: 10.1371/journal.pone.0013098] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 09/02/2010] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Human brain aging has received special attention in part because of the elevated risks of neurodegenerative disorders such as Alzheimer's disease in seniors. Recent technological advances enable us to investigate whether similar mechanisms underlie aging and neurodegeneration, by quantifying the similarities and differences in their genome-wide gene expression profiles. PRINCIPAL FINDINGS We have developed a computational method for assessing an individual's "physiological brain age" by comparing global mRNA expression datasets across a range of normal human brain samples. Application of this method to brains samples from select regions in two diseases--Alzheimer's disease (AD, superior frontal gyrus), frontotemporal lobar degeneration (FTLD, in rostral aspect of frontal cortex ∼BA10)--showed that while control cohorts exhibited no significant difference between physiological and chronological ages, FTLD and AD exhibited prematurely aged expression profiles. CONCLUSIONS This study establishes a quantitative scale for measuring premature aging in neurodegenerative disease cohorts, and it identifies specific physiological mechanisms common to aging and some forms of neurodegeneration. In addition, accelerated expression profiles associated with AD and FTLD suggest some common mechanisms underlying the risk of developing these diseases.
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Affiliation(s)
- Kajia Cao
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Penn Center for Bioinformatics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Alice S. Chen-Plotkin
- Department of Neurology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Institute on Aging, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Center for Neurodegenerative Diseases, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Joshua B. Plotkin
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Li-San Wang
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Institute on Aging, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Penn Center for Bioinformatics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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255
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Vivithanaporn P, Maingat F, Lin LT, Na H, Richardson CD, Agrawal B, Cohen ÉA, Jhamandas JH, Power C. Hepatitis C virus core protein induces neuroimmune activation and potentiates Human Immunodeficiency Virus-1 neurotoxicity. PLoS One 2010; 5:e12856. [PMID: 20877724 PMCID: PMC2943470 DOI: 10.1371/journal.pone.0012856] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 08/18/2010] [Indexed: 12/11/2022] Open
Abstract
Background Hepatitis C virus (HCV) genomes and proteins are present in human brain tissues although the impact of HIV/HCV co-infection on neuropathogenesis remains unclear. Herein, we investigate HCV infectivity and effects on neuronal survival and neuroinflammation in conjunction with HIV infection. Methodology Human microglia, astrocyte and neuron cultures were infected with cell culture-derived HCV or exposed to HCV core protein with or without HIV-1 infection or HIV-1 Viral Protein R (Vpr) exposure. Host immune gene expression and cell viability were measured. Patch-clamp studies of human neurons were performed in the presence or absence of HCV core protein. Neurobehavioral performance and neuropathology were examined in HIV-1 Vpr-transgenic mice in which stereotaxic intrastriatal implants of HCV core protein were performed. Principal Findings HCV-encoded RNA as well as HCV core and non-structural 3 (NS3) proteins were detectable in human microglia and astrocytes infected with HCV. HCV core protein exposure induced expression of pro-inflammatory cytokines including interleukin-1β, interleukin-6 and tumor necrosis factor-α in microglia (p<0.05) but not in astrocytes while increased chemokine (e.g. CXCL10 and interleukin-8) expression was observed in both microglia and astrocytes (p<0.05). HCV core protein modulated neuronal membrane currents and reduced both β-III-tubulin and lipidated LC3-II expression (p<0.05). Neurons exposed to supernatants from HCV core-activated microglia exhibited reduced β-III-tubulin expression (p<0.05). HCV core protein neurotoxicity and interleukin-6 induction were potentiated by HIV-1 Vpr protein (p<0.05). HIV-1 Vpr transgenic mice implanted with HCV core protein showed gliosis, reduced neuronal counts together with diminished LC3 immunoreactivity. HCV core-implanted animals displayed neurobehavioral deficits at days 7 and 14 post-implantation (p<0.05). Conclusions HCV core protein exposure caused neuronal injury through suppression of neuronal autophagy in addition to neuroimmune activation. The additive neurotoxic effects of HCV- and HIV-encoded proteins highlight extrahepatic mechanisms by which HCV infection worsens the disease course of HIV infection.
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Affiliation(s)
- Pornpun Vivithanaporn
- Division of Neurology, University of Alberta, Edmonton, Alberta, Canada
- Department of Pharmacology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Ferdinand Maingat
- Division of Neurology, University of Alberta, Edmonton, Alberta, Canada
| | - Liang-Tzung Lin
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Hong Na
- Division of Neurology, University of Alberta, Edmonton, Alberta, Canada
| | | | - Babita Agrawal
- Department of Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - Éric A. Cohen
- Institut de recherches cliniques de Montréal (IRCM) and Department of Microbiology and Immunology, University of Montreal, Montreal, Quebec, Canada
| | - Jack H. Jhamandas
- Division of Neurology, University of Alberta, Edmonton, Alberta, Canada
| | - Christopher Power
- Division of Neurology, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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256
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Orenstein SJ, Cuervo AM. Chaperone-mediated autophagy: molecular mechanisms and physiological relevance. Semin Cell Dev Biol 2010; 21:719-26. [PMID: 20176123 PMCID: PMC2914824 DOI: 10.1016/j.semcdb.2010.02.005] [Citation(s) in RCA: 184] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 02/07/2010] [Accepted: 02/15/2010] [Indexed: 11/18/2022]
Abstract
Chaperone-mediated autophagy (CMA) is a selective lysosomal pathway for the degradation of cytosolic proteins. We review in this work some of the recent findings on this pathway regarding the molecular mechanisms that contribute to substrate targeting, binding and translocation across the lysosomal membrane. We have placed particular emphasis on the critical role that changes in the lipid composition of the lysosomal membrane play in the regulation of CMA, as well as the modulatory effect of other novel CMA components. In the second part of this review, we describe the physiological relevance of CMA and its role as one of the cellular mechanisms involved in the response to stress. Changes with age in CMA activity and the contribution of failure of CMA to the phenotype of aging and to the pathogenesis of several age-related pathologies are also described.
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Affiliation(s)
- Samantha J. Orenstein
- Department of Developmental and Molecular Biology, Marion Bessin Liver Research Center, Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA, 10461
| | - Ana Maria Cuervo
- Department of Developmental and Molecular Biology, Marion Bessin Liver Research Center, Institute for Aging Research, Albert Einstein College of Medicine, Bronx, NY, USA, 10461
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257
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Zijlstra MP, Rujano MA, Van Waarde MA, Vis E, Brunt ER, Kampinga HH. Levels of DNAJB family members (HSP40) correlate with disease onset in patients with spinocerebellar ataxia type 3. Eur J Neurosci 2010; 32:760-70. [DOI: 10.1111/j.1460-9568.2010.07352.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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258
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Li C, Guo Y, Xie W, Li X, Janokovic J, Le W. Neuroprotection of pramipexole in UPS impairment induced animal model of Parkinson's disease. Neurochem Res 2010; 35:1546-56. [PMID: 20635141 DOI: 10.1007/s11064-010-0214-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2010] [Indexed: 12/21/2022]
Abstract
Pramipexole (PPX), a dopamine (DA) receptor D3 preferring agonist, has been used as monotherapy or adjunct therapy to treat Parkinson's disease (PD) for many years. Several in vitro and in vivo studies in neurotoxin-induced DA neuron injury models have reported that PPX may possess neuroprotective properties. The present study is to evaluate the neuroprotection of PPX in a sustained DA neuron degeneration model of PD induced by ubiquitin-proteasome system (UPS) impairment. Adult C57BL/6 mice were treated with PPX (low dose 0.1 mg/kg or high dose 0.5 mg/kg, i.p, twice a day) started 7 days before, and continued after microinjection of proteasome inhibitor lactacystin in the medial forebrain bundle for a total 4 weeks. Animal behavior observation, and pathological and biochemical assays were conducted to determine the neuroprotective effects of PPX. We report here that PPX treatment significantly improves rotarod performance, attenuates DA neuron loss and striatal DA reduction, and alleviates proteasomal inhibition and microglial activation in the substantia nigra of lactacystin-lesioned mice. PPX can increase the levels of brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor and induce an activation of autophagy. Furthermore, pretreatment with D3 receptor antagonist U99194 can significantly block the PPX-mediated neuroprotection. These results suggest that multiple molecular pathways may be attributed to the neuroprotective effects of PPX in the UPS impairment model of PD.
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Affiliation(s)
- Chao Li
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
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259
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Nogalska A, D'Agostino C, Terracciano C, Engel WK, Askanas V. Impaired autophagy in sporadic inclusion-body myositis and in endoplasmic reticulum stress-provoked cultured human muscle fibers. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:1377-87. [PMID: 20616343 DOI: 10.2353/ajpath.2010.100050] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The hallmark pathologies of sporadic inclusion-body myositis (s-IBM) muscle fibers are autophagic vacuoles and accumulation of ubiquitin-positive multiprotein aggregates that contain amyloid-beta or phosphorylated tau in a beta-pleated sheet amyloid configuration. Endoplasmic reticulum stress (ERS) and 26S proteasome inhibition, also associated with s-IBM, putatively aggrandize the accumulation of misfolded proteins. However, autophagosomal-lysosomal pathway formation and function, indicated by autophagosome maturation, have not been previously analyzed in this system. Here we studied the autophagosomal-lysosomal pathway using 14 s-IBM and 30 disease control and normal control muscle biopsy samples and our cultured human muscle fibers in a microenvironment modified to resemble aspects of s-IBM pathology. We report for the first time that in s-IBM, lysosomal enzyme activities of cathepsin D and B were decreased 60% (P < 0.01) and 40% (P < 0.05), respectively. We also detected two indicators of increased autophagosome maturation, the presence of LC3-II and decreased mammalian target of rapamycin-mediated phosphorylation of p70S6 kinase. Moreover, in cultured human muscle fibers, ERS induction significantly decreased activities of cathepsins D and B, increased levels of LC3-II, decreased phosphorylation of p70S6 kinase, and decreased expression of VMA21, a chaperone for assembly of lysosomal V-ATPase. We conclude that in s-IBM muscle, decreased lysosomal proteolytic activity might enhance accumulation of misfolded proteins, despite increased maturation of autophagosomes, and that ERS is a possible cause of s-IBM-impaired lysosomal function. Thus, unblocking protein degradation in s-IBM muscle fibers may be a desirable therapeutic strategy.
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Affiliation(s)
- Anna Nogalska
- USC Neuromuscular Center, Department of Neurology, University of Southern California Keck School of Medicine, Good Samaritan Hospital, Los Angeles, CA 90017-1912, USA
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260
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Cuervo AM, Wong ESP, Martinez-Vicente M. Protein degradation, aggregation, and misfolding. Mov Disord 2010; 25 Suppl 1:S49-54. [PMID: 20187257 DOI: 10.1002/mds.22718] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The cellular surveillance systems guarantee proper removal of altered components from inside cells. Alterations of these systems in neurons have been proposed to be involved in the pathogenesis of different neurodegenerative disorders. In this review, we comment on the advances in our current understanding of how changes in the intracellular proteolytic systems, the main components of the cellular quality control system, contribute to neurodegeneration, with special emphasis on Parkinson's disease.
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Affiliation(s)
- Ana Maria Cuervo
- Department of Developmental and Molecular Biology, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
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261
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Abstract
Continuous renewal of intracellular components is required to preserve cellular functionality. In fact, failure to timely turnover proteins and organelles leads often to cell death and disease. Different pathways contribute to the degradation of intracellular components in lysosomes or autophagy. In this review, we focus on chaperone-mediated autophagy (CMA), a selective form of autophagy that modulates the turnover of a specific pool of soluble cytosolic proteins. Selectivity in CMA is conferred by the presence of a targeting motif in the cytosolic substrates that, upon recognition by a cytosolic chaperone, determines delivery to the lysosomal surface. Substrate proteins undergo unfolding and translocation across the lysosomal membrane before reaching the lumen, where they are rapidly degraded. Better molecular characterization of the different components of this pathway in recent years, along with the development of transgenic models with modified CMA activity and the identification of CMA dysfunction in different severe human pathologies and in aging, are all behind the recent regained interest in this catabolic pathway.
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262
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Schapira AHV, Tolosa E. Molecular and clinical prodrome of Parkinson disease: implications for treatment. Nat Rev Neurol 2010; 6:309-17. [PMID: 20479780 DOI: 10.1038/nrneurol.2010.52] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The development of interventions to slow or prevent progression represents an important aim for current research into Parkinson disease (PD). General agreement prevails that success in this endeavor will depend on a clearer understanding of etiology and pathogenesis, and several important advances have recently been made, particularly in defining the genetic causes of PD. Studies of the biochemical consequences of the mutations that cause familial PD, and postmortem brain studies of idiopathic, sporadic PD, have highlighted mitochondrial dysfunction, oxidative stress, and protein metabolism by the ubiquitin-proteasomal and autophagy systems as being central to pathogenesis. In parallel with advances in etiopathogenesis, a clearer perception has developed of the clinical prodrome of PD, offering an opportunity to identify individuals who are at risk of PD, as well as those in the earliest clinical phase of the disease that might even precede the onset of motor symptoms. These populations are potentially the most suitable in which to test new protective therapies, and to study potential peripheral markers of disease progression. The awareness of the early symptomatic period of PD also raises the possibility of providing treatments that not only improve motor function but might also favorably modify outcome.
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Affiliation(s)
- Anthony H V Schapira
- Department of Clinical Neurosciences, Institute of Neurology, University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
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263
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Bartolini M, Andrisano V. Strategies for the Inhibition of Protein Aggregation in Human Diseases. Chembiochem 2010; 11:1018-35. [DOI: 10.1002/cbic.200900666] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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264
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Serotonergic dystrophy induced by excess serotonin. Mol Cell Neurosci 2010; 44:297-306. [PMID: 20394820 DOI: 10.1016/j.mcn.2010.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 03/18/2010] [Accepted: 04/02/2010] [Indexed: 01/15/2023] Open
Abstract
Administration of certain serotonin-releasing amphetamine derivatives (fenfluramine and/or 3,4-methylenedioxymethamphetamine, MDMA, 'ecstasy') results in dystrophic serotonergic morphology in the mammalian brain. In addition to drug administration, dystrophic serotonergic neurites are also associated with neurodegenerative disorders. We demonstrate here that endogenously elevated serotonin in the Drosophila CNS induces aberrant enlarged varicosities, or spheroids, that are morphologically similar to dystrophic mammalian serotonergic fibers. In Drosophila these spheroids are specific to serotonergic neurons, distinct from typical varicosities, and form only after prolonged increases in cytoplasmic serotonin. Our results also suggest that serotonin levels during early development determine later sensitivity of spheroid formation to manipulations of the serotonin transporter (SERT). Elevated serotonin also interacts with canonical protein aggregation and autophagic pathways to form spheroids. The data presented here support a model in which excess cytoplasmic neurotransmitter triggers a cell-specific pathway inducing aberrant morphology in fly serotonergic neurons that may be shared in certain mammalian pathologies.
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265
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Yamamoto K, Seki T, Adachi N, Takahashi T, Tanaka S, Hide I, Saito N, Sakai N. Mutant protein kinase C gamma that causes spinocerebellar ataxia type 14 (SCA14) is selectively degraded by autophagy. Genes Cells 2010; 15:425-38. [PMID: 20398063 DOI: 10.1111/j.1365-2443.2010.01395.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several causal missense mutations in the protein kinase Cgamma (gammaPKC) gene have been found in spinocerebellar ataxia type 14 (SCA14), an autosomal dominant neurodegenerative disease. We previously showed that mutant gammaPKC found in SCA14 is susceptible to aggregation and causes apoptosis. Aggregation of misfolded proteins is generally involved in the pathogenesis of many neurodegenerative diseases. Growing evidence indicates that macroautophagy (autophagy) is important for the degradation of misfolded proteins and the prevention of neurodegenerative diseases. In the present study, we examined whether autophagy is involved in the degradation of the mutant gammaPKC that causes SCA14. Mutant gammaPKC-GFP was transiently expressed in SH-SY5Y cells by using an adenoviral tetracycline-regulated system. Subsequently, temporal changes in clearance of aggregates and degradation of gammaPKC-GFP were evaluated. Rapamycin, an autophagic inducer, accelerated clearance of aggregates and promoted degradation of mutant gammaPKC-GFP, but it did not affect degradation of wild-type gammaPKC-GFP. These effects of rapamycin were not observed in embryonic fibroblast cells from Atg5-deficient mice, which are not able to perform autophagy. Furthermore, lithium, another type of autophagic inducer, also promoted the clearance of mutant gammaPKC aggregates. These results indicate that autophagy contributes to the degradation of mutant gammaPKC, suggesting that autophagic inducers could provide therapeutic potential for SCA14.
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Affiliation(s)
- Kazuhiro Yamamoto
- Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi Minami-ku, Hiroshima 734-8551, Japan
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266
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Carr G, Williams DE, Díaz-Marrero AR, Patrick BO, Bottriell H, Balgi AD, Donohue E, Roberge M, Andersen RJ. Bafilomycins produced in culture by Streptomyces spp. isolated from marine habitats are potent inhibitors of autophagy. JOURNAL OF NATURAL PRODUCTS 2010; 73:422-427. [PMID: 20028134 DOI: 10.1021/np900632r] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Five new bafilomycins, F (1) to J (5), have been isolated from laboratory cultures of two Streptomyces spp. obtained from marine sediments collected in British Columbia, and their structures have been elucidated by detailed analysis of spectroscopic data and the synthesis of model compounds. The new bafilomycins F (1), G (2), H (3), and J (5) along with several co-occurring known analogues showed potent inhibition of autophagy in microscopy and biochemical assays. The thiomorpholinone fragment present in bafilomycin F (1) has not previously been found in a natural product.
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Affiliation(s)
- Gavin Carr
- Department of Chemistry, University of British Columbia, Vancouver, B.C., Canada
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267
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Cox LE, Ferraiuolo L, Goodall EF, Heath PR, Higginbottom A, Mortiboys H, Hollinger HC, Hartley JA, Brockington A, Burness CE, Morrison KE, Wharton SB, Grierson AJ, Ince PG, Kirby J, Shaw PJ. Mutations in CHMP2B in lower motor neuron predominant amyotrophic lateral sclerosis (ALS). PLoS One 2010; 5:e9872. [PMID: 20352044 PMCID: PMC2844426 DOI: 10.1371/journal.pone.0009872] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 01/28/2010] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Amyotrophic lateral sclerosis (ALS), a common late-onset neurodegenerative disease, is associated with fronto-temporal dementia (FTD) in 3-10% of patients. A mutation in CHMP2B was recently identified in a Danish pedigree with autosomal dominant FTD. Subsequently, two unrelated patients with familial ALS, one of whom also showed features of FTD, were shown to carry missense mutations in CHMP2B. The initial aim of this study was to determine whether mutations in CHMP2B contribute more broadly to ALS pathogenesis. METHODOLOGY/PRINCIPAL FINDINGS Sequencing of CHMP2B in 433 ALS cases from the North of England identified 4 cases carrying 3 missense mutations, including one novel mutation, p.Thr104Asn, none of which were present in 500 neurologically normal controls. Analysis of clinical and neuropathological data of these 4 cases showed a phenotype consistent with the lower motor neuron predominant (progressive muscular atrophy (PMA)) variant of ALS. Only one had a recognised family history of ALS and none had clinically apparent dementia. Microarray analysis of motor neurons from CHMP2B cases, compared to controls, showed a distinct gene expression signature with significant differential expression predicting disassembly of cell structure; increased calcium concentration in the ER lumen; decrease in the availability of ATP; down-regulation of the classical and p38 MAPK signalling pathways, reduction in autophagy initiation and a global repression of translation. Transfection of mutant CHMP2B into HEK-293 and COS-7 cells resulted in the formation of large cytoplasmic vacuoles, aberrant lysosomal localisation demonstrated by CD63 staining and impairment of autophagy indicated by increased levels of LC3-II protein. These changes were absent in control cells transfected with wild-type CHMP2B. CONCLUSIONS/SIGNIFICANCE We conclude that in a population drawn from North of England pathogenic CHMP2B mutations are found in approximately 1% of cases of ALS and 10% of those with lower motor neuron predominant ALS. We provide a body of evidence indicating the likely pathogenicity of the reported gene alterations. However, absolute confirmation of pathogenicity requires further evidence, including documentation of familial transmission in ALS pedigrees which might be most fruitfully explored in cases with a LMN predominant phenotype.
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Affiliation(s)
- Laura E. Cox
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Laura Ferraiuolo
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Emily F. Goodall
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Paul R. Heath
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Adrian Higginbottom
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Heather Mortiboys
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Hannah C. Hollinger
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Judith A. Hartley
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Alice Brockington
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Christine E. Burness
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Karen E. Morrison
- Department of Neurology, University of Birmingham, Birmingham, East Midlands, United Kingdom
| | - Stephen B. Wharton
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Andrew J. Grierson
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Paul G. Ince
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Janine Kirby
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
| | - Pamela J. Shaw
- Department of Neuroscience, University of Sheffield, Sheffield, South Yorkshire, United Kingdom
- * E-mail:
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Abstract
Understanding how cells handle and dispose of misfolded proteins is of paramount importance because protein misfolding and aggregation underlie the pathogenesis of many neurodegenerative disorders, including PD (Parkinson's disease) and Alzheimer's disease. In addition to the ubiquitin-proteasome system, the aggresome-autophagy pathway has emerged as another crucial cellular defence system against toxic build-up of misfolded proteins. In contrast with basal autophagy that mediates non-selective, bulk clearance of misfolded proteins along with normal cellular proteins and organelles, the aggresome-autophagy pathway is increasingly recognized as a specialized type of induced autophagy that mediates selective clearance of misfolded and aggregated proteins under the conditions of proteotoxic stress. Recent evidence implicates PD-linked E3 ligase parkin as a key regulator of the aggresome-autophagy pathway and indicates a signalling role for Lys(63)-linked polyubiquitination in the regulation of aggresome formation and autophagy. The present review summarizes the current knowledge of the aggresome-autophagy pathway, its regulation by parkin-mediated Lys(63)-linked polyubiquitination, and its dysfunction in neurodegenerative diseases.
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Zhang C, Browne A, Child D, Divito JR, Stevenson JA, Tanzi RE. Loss of function of ATXN1 increases amyloid beta-protein levels by potentiating beta-secretase processing of beta-amyloid precursor protein. J Biol Chem 2010; 285:8515-26. [PMID: 20097758 DOI: 10.1074/jbc.m109.079079] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Alzheimer disease (AD) is a devastating neurodegenerative disease with complex and strong genetic inheritance. Four genes have been established to either cause familial early onset AD (APP, PSEN1, and PSEN2) or to increase susceptibility for late onset AD (APOE). To date approximately 80% of the late onset AD genetic variance remains elusive. Recently our genome-wide association screen identified four novel late onset AD candidate genes. Ataxin 1 (ATXN1) is one of these four AD candidate genes and has been indicated to be the disease gene for spinocerebellar ataxia type 1, which is also a neurodegenerative disease. Mounting evidence suggests that the excessive accumulation of Abeta, the proteolytic product of beta-amyloid precursor protein (APP), is the primary AD pathological event. In this study, we ask whether ATXN1 may lead to AD pathogenesis by affecting Abeta and APP processing utilizing RNA interference in a human neuronal cell model and mouse primary cortical neurons. We show that knock-down of ATXN1 significantly increases the levels of both Abeta40 and Abeta42. This effect could be rescued with concurrent overexpression of ATXN1. Moreover, overexpression of ATXN1 decreased Abeta levels. Regarding the underlying molecular mechanism, we show that the effect of ATXN1 expression on Abeta levels is modulated via beta-secretase cleavage of APP. Taken together, ATXN1 functions as a genetic risk modifier that contributes to AD pathogenesis through a loss-of-function mechanism by regulating beta-secretase cleavage of APP and Abeta levels.
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Affiliation(s)
- Can Zhang
- Department of Neurology, Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts 02129-2060, USA
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271
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Michiorri S, Gelmetti V, Giarda E, Lombardi F, Romano F, Marongiu R, Nerini-Molteni S, Sale P, Vago R, Arena G, Torosantucci L, Cassina L, Russo MA, Dallapiccola B, Valente EM, Casari G. The Parkinson-associated protein PINK1 interacts with Beclin1 and promotes autophagy. Cell Death Differ 2010; 17:962-74. [PMID: 20057503 DOI: 10.1038/cdd.2009.200] [Citation(s) in RCA: 207] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mutations in the PINK1 gene cause autosomal recessive Parkinson's disease. The PINK1 gene encodes a protein kinase that is mitochondrially cleaved to generate two mature isoforms. In addition to its protective role against mitochondrial dysfunction and apoptosis, PINK1 is also known to regulate mitochondrial dynamics acting upstream of the PD-related protein Parkin. Recent data showed that mitochondrial Parkin promotes the autophagic degradation of dysfunctional mitochondria, and that stable PINK1 silencing may have an indirect role in mitophagy activation. Here we report a new interaction between PINK1 and Beclin1, a key pro-autophagic protein already implicated in the pathogenesis of Alzheimer's and Huntington's diseases. Both PINK1 N- and C-terminal are required for the interaction, suggesting that full-length PINK1, and not its cleaved isoforms, interacts with Beclin1. We also demonstrate that PINK1 significantly enhances basal and starvation-induced autophagy, which is reduced by knocking down Beclin1 expression or by inhibiting the Beclin1 partner Vps34. A mutant, PINK1(W437X), interaction of which with Beclin1 is largely impaired, lacks the ability to enhance autophagy, whereas this is not observed for PINK1(G309D), a mutant with defective kinase activity but unaltered ability to bind Beclin1. These findings identify a new function of PINK1 and further strengthen the link between autophagy and proteins implicated in the neurodegenerative process.
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Affiliation(s)
- S Michiorri
- Casa Sollievo della Sofferenza Hospital, CSS-Mendel Institute, Rome, Italy
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272
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Depuydt G, Vanfleteren JR, Braeckman BP. Protein metabolism and lifespan in Caenorhabditis elegans. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 694:81-107. [PMID: 20886759 DOI: 10.1007/978-1-4419-7002-2_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Lifespan of the versatile model system Caenorhabditis elegans can be extended by a decrease of insulin/IGF-1 signaling, TOR signaling, mitochondrial function, protein synthesis and dietary intake. The exact molecular mechanisms by which these modulations confer increased life expectancy are yet to be determined but increased stress resistance and improved protein homeostasis seem to be of major importance. In this chapter, we explore the interactions among several genetic pathways and cellular functions involved in lifespan extension and their relation to protein homeostasis in C. elegans. Several of these processes have been associated, however some relevant data are conflicting and further studies are needed to clarify these interactions. In mammals, protein homeostasis is also implicated in several neurodegenerative diseases, many of which can be modeled in C. elegans.
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Affiliation(s)
- Geert Depuydt
- Department of Biology, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
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273
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Funderburk SF, Marcellino BK, Yue Z. Cell "self-eating" (autophagy) mechanism in Alzheimer's disease. THE MOUNT SINAI JOURNAL OF MEDICINE, NEW YORK 2010; 77:59-68. [PMID: 20101724 PMCID: PMC2835623 DOI: 10.1002/msj.20161] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The autophagy pathway is the major degradation pathway of the cell for long-lived proteins and organelles. Dysfunction of autophagy has been linked to several neurodegenerative disorders that are associated with an accumulation of misfolded protein aggregates. Alzheimer's disease, the most common neurodegenerative disorder, is characterized by 2 aggregate forms, tau tangles and amyloid-beta plaques. Autophagy has been linked to Alzheimer's disease pathogenesis through its merger with the endosomal-lysosomal system, which has been shown to play a role in the formation of the latter amyloid-beta plaques. However, the precise role of autophagy in Alzheimer's disease pathogenesis is still under contention. One hypothesis is that aberrant autophagy induction results in an accumulation of autophagic vacuoles containing amyloid-beta and the components necessary for its generation, whereas other evidence points to impaired autophagic clearance or even an overall reduction in autophagic activity playing a role in Alzheimer's disease pathogenesis. In this review, we discuss the current evidence linking autophagy to Alzheimer's disease as well as the uncertainty over the exact role and level of autophagic regulation in the pathogenic mechanism of Alzheimer's disease.
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Affiliation(s)
- Sarah F Funderburk
- Department of Neurology, Mount Sinai School of Medicine, New York, NY, USA
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274
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Kon M, Cuervo AM. Chaperone-mediated autophagy in health and disease. FEBS Lett 2009; 584:1399-404. [PMID: 20026330 DOI: 10.1016/j.febslet.2009.12.025] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Revised: 12/13/2009] [Accepted: 12/15/2009] [Indexed: 11/18/2022]
Abstract
Chaperone-mediated autophagy (CMA) is a lysosomal pathway that participates in the degradation of cytosolic proteins. CMA is activated by starvation and in response to stressors that result in protein damage. The selectivity intrinsic to CMA allows for removal of damaged proteins without disturbing nearby functional ones. CMA works in a coordinated manner with other autophagic pathways, which can compensate for each other. Interest in CMA has recently grown because of the connections established between this autophagic pathway and human pathologies. Here we review the unique properties of CMA compared to other autophagic pathways and its relevance in health and disease.
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Affiliation(s)
- Maria Kon
- Department of Developmental and Molecular Biology, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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275
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Thompson LM, Aiken CT, Kaltenbach LS, Agrawal N, Illes K, Khoshnan A, Martinez-Vincente M, Arrasate M, O'Rourke JG, Khashwji H, Lukacsovich T, Zhu YZ, Lau AL, Massey A, Hayden MR, Zeitlin SO, Finkbeiner S, Green KN, LaFerla FM, Bates G, Huang L, Patterson PH, Lo DC, Cuervo AM, Marsh JL, Steffan JS. IKK phosphorylates Huntingtin and targets it for degradation by the proteasome and lysosome. ACTA ACUST UNITED AC 2009; 187:1083-99. [PMID: 20026656 PMCID: PMC2806289 DOI: 10.1083/jcb.200909067] [Citation(s) in RCA: 275] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Expansion of the polyglutamine repeat within the protein Huntingtin (Htt) causes Huntington's disease, a neurodegenerative disease associated with aging and the accumulation of mutant Htt in diseased neurons. Understanding the mechanisms that influence Htt cellular degradation may target treatments designed to activate mutant Htt clearance pathways. We find that Htt is phosphorylated by the inflammatory kinase IKK, enhancing its normal clearance by the proteasome and lysosome. Phosphorylation of Htt regulates additional post-translational modifications, including Htt ubiquitination, SUMOylation, and acetylation, and increases Htt nuclear localization, cleavage, and clearance mediated by lysosomal-associated membrane protein 2A and Hsc70. We propose that IKK activates mutant Htt clearance until an age-related loss of proteasome/lysosome function promotes accumulation of toxic post-translationally modified mutant Htt. Thus, IKK activation may modulate mutant Htt neurotoxicity depending on the cell's ability to degrade the modified species.
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276
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Xiong N, Huang J, Zhang Z, Zhang Z, Xiong J, Liu X, Jia M, Wang F, Chen C, Cao X, Liang Z, Sun S, Lin Z, Wang T. Stereotaxical infusion of rotenone: a reliable rodent model for Parkinson's disease. PLoS One 2009; 4:e7878. [PMID: 19924288 PMCID: PMC2774159 DOI: 10.1371/journal.pone.0007878] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 10/04/2009] [Indexed: 12/21/2022] Open
Abstract
A clinically-related animal model of Parkinson's disease (PD) may enable the elucidation of the etiology of the disease and assist the development of medications. However, none of the current neurotoxin-based models recapitulates the main clinical features of the disease or the pathological hallmarks, such as dopamine (DA) neuron specificity of degeneration and Lewy body formation, which limits the use of these models in PD research. To overcome these limitations, we developed a rat model by stereotaxically (ST) infusing small doses of the mitochondrial complex-I inhibitor, rotenone, into two brain sites: the right ventral tegmental area and the substantia nigra. Four weeks after ST rotenone administration, tyrosine hydroxylase (TH) immunoreactivity in the infusion side decreased by 43.7%, in contrast to a 75.8% decrease observed in rats treated systemically with rotenone (SYS). The rotenone infusion also reduced the DA content, the glutathione and superoxide dismutase activities, and induced alpha-synuclein expression, when compared to the contralateral side. This ST model displays neither peripheral toxicity or mortality and has a high success rate. This rotenone-based ST model thus recapitulates the slow and specific loss of DA neurons and better mimics the clinical features of idiopathic PD, representing a reliable and more clinically-related model for PD research.
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Affiliation(s)
- Nian Xiong
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Jinsha Huang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Zhentao Zhang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Zhaowen Zhang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Jing Xiong
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Xingyuan Liu
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Min Jia
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Fang Wang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Chunnuan Chen
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Xuebing Cao
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Zhihou Liang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Shenggang Sun
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Zhicheng Lin
- Department of Psychiatry, Harvard Medical School, Boston, Massachusetts, United States of America
- Mailman Research Center, McLean Hospital, Belmont, Massachusetts, United States of America
| | - Tao Wang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
- * E-mail:
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277
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Tinsley RB, Bye CR, Parish CL, Tziotis-Vais A, George S, Culvenor JG, Li QX, Masters CL, Finkelstein DI, Horne MK. Dopamine D2 receptor knockout mice develop features of Parkinson disease. Ann Neurol 2009; 66:472-84. [PMID: 19847912 DOI: 10.1002/ana.21716] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE This study questions whether increased dopamine (DA) turnover in nigral neurons leads to formation of Lewy bodies (LBs), the characteristic alpha-synuclein-containing cytoplasmic inclusion of Parkinson disease (PD). METHODS Mice with targeted deletion of the dopamine D(2) receptor gene (D(2)R[-/-]) have higher striatal and nigral dopamine turnover and elevated oxidative stress. These mice were examined for evidence of histological, biochemical, and gene expression changes consistent with a synucleinopathy. RESULTS LB-like cytoplasmic inclusions containing alpha-synuclein and ubiquitin were present in substantia nigra pars compacta (SNpc) neurons of older D(2)R(-/-) mice, and were also occasionally seen in aged wild-type mice. These inclusions displaced the nucleus of affected cells and were eosinophilic. Diffuse cytosolic alpha-synuclein immunoreactivity in SNpc neurons increased with age in both wild-type and D(2)R(-/-) mice, most likely because of redistribution of alpha-synuclein from striatal terminals to SNpc cell bodies. Gene and protein expression studies indicated endoplasmic reticulum (ER) stress and changes in trafficking and autophagic pathways in D(2)R(-/-) SNpc. These changes were accompanied by a loss of DA terminals in the dorsal striatum, although there was no evidence of progressive cell death in the SNpc. INTERPRETATION Increased sprouting and DA turnover, as observed in PD and D(2)R(-/-) mice, augments LB-like inclusions and axonal degeneration of dopaminergic neurons. These changes are associated with ER stress and autophagy.
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Affiliation(s)
- Rogan B Tinsley
- Howard Florey Institute, the University of Melbourne, Parkville, Australia
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278
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Birk J, Friberg MA, Prescianotto-Baschong C, Spiess M, Rutishauser J. Dominant pro-vasopressin mutants that cause diabetes insipidus form disulfide-linked fibrillar aggregates in the endoplasmic reticulum. J Cell Sci 2009; 122:3994-4002. [PMID: 19825939 DOI: 10.1242/jcs.051136] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Autosomal dominant neurohypophyseal diabetes insipidus results from mutations in the precursor protein of the antidiuretic hormone arginine vasopressin. Mutant prohormone is retained in the endoplasmic reticulum of vasopressinergic neurons and causes their progressive degeneration by an unknown mechanism. Here, we show that several dominant pro-vasopressin mutants form disulfide-linked homo-oligomers and develop large aggregations visible by immunofluorescence and immunogold electron microscopy, both in a fibroblast and a neuronal cell line. Double-labeling showed the pro-vasopressin aggregates to colocalize with the chaperone calreticulin, indicating that they originated from the endoplasmic reticulum. The aggregates revealed a remarkable fibrillar substructure. Bacterially expressed and purified mutant pro-vasopressin spontaneously formed fibrils under oxidizing conditions. Mutagenesis experiments showed that the presence of cysteines, but no specific single cysteine, is essential for disulfide oligomerization and aggregation in vivo. Our findings assign autosomal dominant diabetes insipidus to the group of neurodegenerative diseases associated with the formation of fibrillar protein aggregates.
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Affiliation(s)
- Julia Birk
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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279
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Golde TE, Miller VM. Proteinopathy-induced neuronal senescence: a hypothesis for brain failure in Alzheimer's and other neurodegenerative diseases. ALZHEIMERS RESEARCH & THERAPY 2009; 1:5. [PMID: 19822029 PMCID: PMC2874257 DOI: 10.1186/alzrt5] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Background Alzheimer's disease (AD) and a host of other neurodegenerative central nervous system (CNS) proteinopathies are characterized by the accumulation of misfolded protein aggregates. Simplistically, these aggregates can be divided into smaller, soluble, oligomeric and larger, less-soluble or insoluble, fibrillar forms. Perhaps the major ongoing debate in the neurodegenerative disease field is whether the smaller oligomeric or larger fibrillar aggregates are the primary neurotoxin. Herein, we propose an integrative hypothesis that provides new insights into how a variety of misfolded protein aggregates can result in neurodegeneration. Results We introduce the concept that a wide range of highly stable misfolded protein aggregates in AD and other neurodegenerative proteinopathies are recognized as non-self and chronically activate the innate immune system. This pro-inflammatory state leads to physiological senescence of CNS cells. Once CNS cells undergo physiological senescence, they secrete a variety of pro-inflammatory molecules. Thus, the senescence of cells, which was initially triggered by inflammatory stimuli, becomes a self-reinforcing stimulus for further inflammation and senescence. Ultimately, senescent CNS cells become functionally impaired and eventually die, and this neurodegeneration leads to brain organ failure. Conclusion This integrative hypothesis, which we will refer to as the proteinopathy-induced senescent cell hypothesis of AD and other neurodegenerative diseases, links CNS proteinopathies to inflammation, physiological senescence, cellular dysfunction, and ultimately neurodegeneration. Future studies characterizing the senescent phenotype of CNS cells in AD and other neurodegenerative diseases will test the validity of this hypothesis. The implications of CNS senescence as a contributing factor to the neurodegenerative cascade and its implications for therapy are discussed.
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Affiliation(s)
- Todd E Golde
- Department of Neuroscience, Mayo Clinic, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, Florida 32224, USA.
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280
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Abnormal localization of leucine-rich repeat kinase 2 to the endosomal-lysosomal compartment in lewy body disease. J Neuropathol Exp Neurol 2009; 68:994-1005. [PMID: 19680143 DOI: 10.1097/nen.0b013e3181b44ed8] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Missense mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common causes of both familial and sporadic forms of Parkinson disease and are also associated with diverse pathological alterations. The mechanisms whereby LRRK2 mutations cause these pathological phenotypes are unknown. We used immunohistochemistry with 3 distinct anti-LRRK2 antibodies to characterize the expression of LRRK2 in the brains of 21 subjects with various neurodegenerative disorders and 7 controls. The immunoreactivity of LRRK2 was localized in a subset of brainstem-type Lewy bodies (LBs) but not in cortical-type LBs, tau-positive inclusions, or TAR-DNA-binding protein-43-positive inclusions. The immunoreactivity of LRRK2 frequently appeared as enlarged granules or vacuoles within neurons of affected brain regions, including the substantia nigra, amygdala, and entorhinal cortex in patients with Parkinson disease or dementia with LBs. The volumes of LRRK2-positive granular structures in neurons of the entorhinal cortex were significantly increased in dementia with LBs brains compared with age-matched control brains (p < 0.05). Double immunolabeling demonstrated that these LRRK2-positive granular structures frequently colocalized with the late-endosomal marker Rab7B and occasionally with the lysosomal marker, the lysosomal-associated membrane protein 2. These results suggest that LRRK2 normally localizes to the endosomal-lysosomal compartment within morphologically altered neurons in neurodegenerative diseases, particularly in the brains of patients with LB diseases.
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281
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282
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Liu HY, Han J, Cao SY, Hong T, Zhuo D, Shi J, Liu Z, Cao W. Hepatic autophagy is suppressed in the presence of insulin resistance and hyperinsulinemia: inhibition of FoxO1-dependent expression of key autophagy genes by insulin. J Biol Chem 2009; 284:31484-92. [PMID: 19758991 DOI: 10.1074/jbc.m109.033936] [Citation(s) in RCA: 311] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Autophagy is essential for maintaining both survival and health of cells. Autophagy is normally suppressed by amino acids and insulin. It is unclear what happens to the autophagy activity in the presence of insulin resistance and hyperinsulinemia. In this study, we examined the autophagy activity in the presence of insulin resistance and hyperinsulinemia and the associated mechanism. Insulin resistance and hyperinsulinemia were induced in mice by a high fat diet, followed by measurements of autophagy markers. Our results show that autophagy was suppressed in the livers of mice with insulin resistance and hyperinsulinemia. Transcript levels of some key autophagy genes were also suppressed in the presence of insulin resistance and hyperinsulinemia. Conversely, autophagy activity was increased in the livers of mice with streptozotocin-induced insulin deficiency. Levels of vps34, atg12, and gabarapl1 transcripts were elevated in the livers of mice with insulin deficiency. To study the mechanism, autophagy was induced by nutrient deprivation or glucagon in cultured hepatocytes in the presence or absence of insulin. Autophagy activity and transcript levels of vps34, atg12, and gabarapl1 genes were reduced by insulin. The effect of insulin was largely prevented by overexpression of the constitutive nuclear form of FoxO1. Importantly, autophagy of mitochondria (mitophagy) in cultured cells was suppressed by insulin in the presence of insulin resistance. Together, our results show that autophagy activity and expression of some key autophagy genes were suppressed in the presence of insulin resistance and hyperinsulinemia. Insulin suppression of autophagy involves FoxO1-mediated transcription of key autophagy genes.
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Affiliation(s)
- Hui-Yu Liu
- Translational Biology, The Hamner Institutes for Health Sciences, Durham, North Carolina 27709, USA
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283
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Cheung ZH, Ip NY. The emerging role of autophagy in Parkinson's disease. Mol Brain 2009; 2:29. [PMID: 19754977 PMCID: PMC2754442 DOI: 10.1186/1756-6606-2-29] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Accepted: 09/16/2009] [Indexed: 12/15/2022] Open
Abstract
Parkinson's disease (PD) is the most common neurodegenerative movement disorder that affects about 1% of the population worldwide. Despite significant advances in the identification of genetic mutations and signaling pathways that are associated with the disease, the precise mechanisms implicated in the pathophysiology of the disease are not well understood. More importantly, treatments that are effective in reversing the progression of the disease is essentially lacking. Further investigation into the pathogenic mechanisms of PD thus presents a pressing concern for neuroscientists. Recently, deregulation of the autophagic pathway is observed in the brains of PD patients and in models of PD. In this review we summarize current literature on the emerging involvement of autophagy in PD, and the implication for future development of treatment against the disorder.
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Affiliation(s)
- Zelda H Cheung
- Department of Biochemistry, Molecular Neuroscience Center and Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China.
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284
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Valente EM, Michiorri S, Arena G, Gelmetti V. PINK1: one protein, multiple neuroprotective functions. FUTURE NEUROLOGY 2009. [DOI: 10.2217/fnl.09.39] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mutations in the PINK1 gene are the second most frequent cause of autosomal recessive parkinsonism after Parkin, and can represent a risk factor towards sporadic Parkinson’s disease. The PINK1 protein product has been implicated in several functions, mostly aimed at protecting neuronal cells against different types of stress. Growing evidence indicates that PINK1 interplays with other proteins mutated in familial forms of Parkinson’s disease, such as Parkin, DJ-1 and α-synuclein. These interactions contribute to the definition of a complex scenario in which the mainteinance of mitochondrial homeostasis and the clearance of misfolded proteins and damaged organelles represent key neuroprotective processes. In this review, we summarize the current knowledge on PINK1 characteristics and functions, and analyze the network of functional relationships that link PINK1 to other Parkinson’s disease-related proteins.
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Affiliation(s)
- Enza Maria Valente
- Neurogenetics Unit, CSS-Mendel Institute, viale Regina Margherita 261, 00198 Rome, Italy and University of Messina, Messina, Italy
| | - Silvia Michiorri
- CSS-Mendel Institute, viale Regina Margherita 261, 00198 Rome, Italy and Department of Experimental Medicine, Sapienza University, Rome, Italy
| | - Giuseppe Arena
- CSS-Mendel Institute, viale Regina Margherita 261, 00198 Rome, Italy
| | - Vania Gelmetti
- CSS-Mendel Institute, viale Regina Margherita 261, 00198 Rome, Italy
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285
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Caccamo A, Majumder S, Deng JJ, Bai Y, Thornton FB, Oddo S. Rapamycin rescues TDP-43 mislocalization and the associated low molecular mass neurofilament instability. J Biol Chem 2009; 284:27416-24. [PMID: 19651785 DOI: 10.1074/jbc.m109.031278] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
TDP-43 is a nuclear protein involved in exon skipping and alternative splicing. Recently, TDP-43 has been identified as the pathological signature protein in frontotemporal lobar degeneration with ubiquitin-positive inclusions and in amyotrophic lateral sclerosis. In addition, TDP-43-positive inclusions are present in Parkinson disease, dementia with Lewy bodies, and 30% of Alzheimer disease cases. Pathological TDP-43 is redistributed from the nucleus to the cytoplasm, where it accumulates. An approximately 25-kDa C-terminal fragment of TDP-43 accumulates in affected brain regions, suggesting that it may be involved in the disease pathogenesis. Here, we show that overexpression of the 25-kDa C-terminal fragment is sufficient to cause the mislocalization and cytoplasmic accumulation of endogenous full-length TDP-43 in two different cell lines, thus recapitulating a key biochemical characteristic of TDP-43 proteinopathies. We also found that TDP-43 mislocalization is associated with a reduction in the low molecular mass neurofilament mRNA levels. Notably, we show that the autophagic system plays a role in TDP-43 metabolism. Specifically, we found that autophagy inhibition increases the accumulation of the C-terminal fragments of TDP-43, whereas inhibition of mTOR, a key protein kinase involved in autophagy regulation, reduces the 25-kDa C-terminal fragment accumulation and restores TDP-43 localization. Our results suggest that autophagy induction may be a valid therapeutic target for TDP-43 proteinopathies.
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Affiliation(s)
- Antonella Caccamo
- Department of Physiology, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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286
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Abstract
Autophagy is a process of lysosomal degradation that was originally described as a cellular response to adapt to a lack of nutrients and to enable the elimination of damaged organelles. Autophagy is increasingly recognized as a process that is also involved in innate and adaptive immune responses against pathogens. Studies on the regulation of autophagy have uncovered components of the autophagic cascade that can be manipulated pharmacologically. Approaches to modulate autophagy may result in novel strategies for the treatment and prevention of various infections.
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Affiliation(s)
- Carlos S Subauste
- Case Western Reserve University School of Medicine, 11100 Euclid Avenue, Cleveland, OH 44106, USA.
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288
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Widodo N, Shah N, Priyandoko D, Ishii T, Kaul SC, Wadhwa R. Deceleration of Senescence in Normal Human Fibroblasts by Withanone Extracted From Ashwagandha Leaves. J Gerontol A Biol Sci Med Sci 2009; 64:1031-8. [DOI: 10.1093/gerona/glp088] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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289
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Abstract
Autophagy is a cellular pathway involved in protein and organelle degradation, which is likely to represent an innate adaptation to starvation. In times of nutrient deficiency, the cell can self-digest and recycle some nonessential components through nonselective autophagy, thus sustaining minimal growth requirements until a food source becomes available. Over recent years, autophagy has been implicated in an increasing number of clinical scenarios, notably infectious diseases, cancer, neurodegenerative diseases, and autoimmunity. The recent identification of the importance of autophagy genes in the genetic susceptibility to Crohn's disease suggests that a selective autophagic response may play a crucial role in the pathogenesis of common complex immune-mediated diseases. In this review, we discuss the autophagic mechanisms, their molecular regulation, and summarize their clinical relevance. This progress has led to great interest in the therapeutic potential of manipulation of both selective and nonselective autophagy in established disease.
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290
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Askanas V, Engel WK, Nogalska A. Inclusion body myositis: a degenerative muscle disease associated with intra-muscle fiber multi-protein aggregates, proteasome inhibition, endoplasmic reticulum stress and decreased lysosomal degradation. Brain Pathol 2009; 19:493-506. [PMID: 19563541 PMCID: PMC8094750 DOI: 10.1111/j.1750-3639.2009.00290.x] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 03/12/2009] [Indexed: 12/31/2022] Open
Abstract
Sporadic inclusion body myositis (s-IBM), the most common muscle disease of older persons, is of unknown cause, and there is no enduring treatment. Abnormal accumulation of intracellular multi-protein inclusions is a characteristic feature of the s-IBM phenotype, and as such s-IBM can be considered a "conformational disorder," caused by protein unfolding/misfolding combined with the formation of inclusion bodies. Abnormal intracellular accumulation of unfolded proteins may lead to their aggregation and inclusion body formation. The present article is focusing on the multiple proteins that are accumulated in the form of aggregates within s-IBM muscle fibers, and it explores the most recent research advances directed toward a better understanding of mechanisms causing their impaired degradation and abnormal aggregation. We illustrate that, among other factors, abnormal misfolding, accumulation and aggregation of proteins are associated with their inadequate disposal-and these factors are combined with, and perhaps provoked by, an aging intracellular milieu. Other concurrent and possibly provocative phenomena known within s-IBM muscle fibers are: endoplasmic reticulum stress and unfolded protein response, mitochondrial abnormalities, proteasome inhibition, lysosome abnormality and endodissolution. Together, these appear to lead to the s-IBM-specific vacuolar degeneration, and muscle fiber atrophy, concluding with muscle fiber death.
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Affiliation(s)
- Valerie Askanas
- USC Neuromuscular Center, Department of Neurology, University of Southern California Keck School of Medicine, Good Samaritan Hospital, Los Angeles, CA 90017-1912, USA.
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291
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292
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Parnetti L, Balducci C, Pierguidi L, De Carlo C, Peducci M, D'Amore C, Padiglioni C, Mastrocola S, Persichetti E, Paciotti S, Bellomo G, Tambasco N, Rossi A, Beccari T, Calabresi P. Cerebrospinal fluid β-glucocerebrosidase activity is reduced in Dementia with Lewy Bodies. Neurobiol Dis 2009; 34:484-6. [DOI: 10.1016/j.nbd.2009.03.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 03/07/2009] [Indexed: 01/18/2023] Open
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293
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Sassone J, Colciago C, Cislaghi G, Silani V, Ciammola A. Huntington's disease: the current state of research with peripheral tissues. Exp Neurol 2009; 219:385-97. [PMID: 19460373 DOI: 10.1016/j.expneurol.2009.05.012] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2008] [Revised: 04/30/2009] [Accepted: 05/09/2009] [Indexed: 01/23/2023]
Abstract
Huntington's disease (HD) is a genetically dominant condition caused by expanded CAG repeats. These repeats code for a glutamine tract in the HD gene product huntingtin (htt), which is a protein expressed in almost all tissues. Although most HD symptoms reflect preferential neuronal death in specific brain regions, even before the HD gene was identified numerous reports had described additional abnormalities in the peripheral tissues of HD patients, including weight loss, altered glucose homeostasis, and sub-cellular abnormalities in fibroblasts, lymphocytes and erythrocytes. Several years have elapsed since the HD mutation was discovered, and analyses of peripheral tissues from HD patients have helped to understand the molecular pathogenesis of the disease and revealed that the molecular mechanisms through which mutated htt leads to cell dysfunction are widely shared between central nervous system (CNS) and peripheral tissues. These studies show that in peripheral tissues, mutated htt causes accumulation of intracellular protein aggregates, impairment of energetic metabolism, transcriptional deregulation and hyperactivation of programmed cell-death mechanisms. Here, we review the current knowledge of peripheral tissue alterations in HD patients and in animal models of HD and focus on how this information can be used to identify potential therapeutic possibilities and biomarkers for disease progression.
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Affiliation(s)
- Jenny Sassone
- Department of Neurology and Laboratory of Neuroscience, Dino Ferrari Center, IRCCS Istituto Auxologico Italiano, University of Milan Medical School, via Spagnoletto 3, 20149, Milan, Italy
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294
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Franch HA. Nutrition and muscle catabolism in maintenance hemodialysis: does feeding make muscle cells selective self-eaters? J Ren Nutr 2009; 19:86-90. [PMID: 19121779 DOI: 10.1053/j.jrn.2008.10.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Efforts to build muscle by increased protein feeding in hemodialysis patients have been thwarted by parallel increases in both muscle protein synthesis and degradation. The evidence suggests that muscle cells replace older proteins in response to feeding rather than using new proteins to drive muscle cell hypertrophy. This review presents the hypothesis that protein feeding provides an opportunity for muscle to accelerate proteolysis of proteins that have been damaged by oxidation, nitrosylation, and/or glycosylation and to replace damaged mitochondria that contribute to oxidative stress. Increases in proteolysis with feeding are driven by insulin resistance and the increased oxidative stress of mitochondrial respiration. Oxidized proteins and organelles are excellent substrates for degradation by the proteasome, macroautophagy, and chaperone-mediated autophagy: these systems of proteolysis seem to be activated by oxydatiative stress. Replacement of oxidized and other damaged proteins may be a benefit of protein feeding in hemodialysis, but alternative strategies, including exercise, will be required to build muscle.
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Affiliation(s)
- Harold A Franch
- Research Service, Atlanta Veterans Affairs Medical Center, Decatur, Georgia, USA.
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295
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Song W, Patel A, Qureshi HY, Han D, Schipper HM, Paudel HK. The Parkinson disease-associated A30P mutation stabilizes alpha-synuclein against proteasomal degradation triggered by heme oxygenase-1 over-expression in human neuroblastoma cells. J Neurochem 2009; 110:719-33. [PMID: 19457084 DOI: 10.1111/j.1471-4159.2009.06165.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Proteosomal degradation of proteins is one of the major mechanisms of intracellular protein turnover. Failure of the proteosome to degrade misfolded protein is implicated in the accumulation of alpha-synuclein in Parkinson's disease (PD). Heme oxygenase-1 (HO-1), an enzyme that converts heme to free iron, carbon monoxide (CO) and biliverdin (bilirubin precursor) is expressed in response to various stressors. HO-1 is up-regulated in PD- and Alzheimer's disease-affected neural tissues. In this study, we found that HO-1 over-expression engenders dose-dependent decreases in alpha-synuclein protein levels in human neuroblastoma M17 cells. When over-expression of HO-1 was silenced in HO-1 transfected cells, level of alpha-synuclein was restored. Likewise, treatment of HO-1 over-expressing cells with the HO-1 inhibitor, tin mesoporphyrin, the iron chelator deferoxamine or antagonist of CO-dependent cGMP activation, methylene blue, mitigated the HO-1-induced reduction in alpha-synuclein levels. Furthermore, when HO-1 over-expressing cells were treated with the proteosome inhibitors, lactacystin and MG132, level of alpha-synuclein was almost completely restored. In contrast to the effect on alpha-synuclein [wild-type (WT)] levels, HO-1 over-expression did not significantly impact PD-associated alpha-synuclein (A30P) levels in these cells. HO-1 also significantly reduced aggregation of alpha-synuclein (WT) but not that of A30P. Our results suggest that HO-1, which is expressed when neurons are exposed to toxic stimuli capable of inducing protein misfolding, triggers proteosomal degradation of proteins and prevents intracellular accumulation of protein aggregates and inclusions. Resistance to HO-1 induced proteosomal degradation may render the familial PD-associated A30P mutation prone to toxic intracellular aggregation.
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Affiliation(s)
- Wei Song
- Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
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296
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Levy OA, Malagelada C, Greene LA. Cell death pathways in Parkinson's disease: proximal triggers, distal effectors, and final steps. Apoptosis 2009; 14:478-500. [PMID: 19165601 DOI: 10.1007/s10495-008-0309-3] [Citation(s) in RCA: 204] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Parkinson's disease (PD) is a common neurodegenerative disorder. Neuronal cell death in PD is still poorly understood, despite a wealth of potential pathogenic mechanisms and pathways. Defects in several cellular systems have been implicated as early triggers that start cells down the road toward neuronal death. These include abnormal protein accumulation, particularly of alpha-synuclein; altered protein degradation via multiple pathways; mitochondrial dysfunction; oxidative stress; neuroinflammation; and dysregulated kinase signaling. As dysfunction in these systems mounts, pathways that are more explicitly involved in cell death become recruited. These include JNK signaling, p53 activation, cell cycle re-activation, and signaling through bcl-2 family proteins. Eventually, neurons become overwhelmed and degenerate; however, even the mechanism of final cell death in PD is still unsettled. In this review, we will discuss cell death triggers and effectors that are relevant to PD, highlighting important unresolved issues and implications for the development of neuroprotective therapies.
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Affiliation(s)
- Oren A Levy
- Department of Neurology, Columbia University School of Medicine, New York, NY, USA
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297
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Jaeger PA, Wyss-Coray T. All-you-can-eat: autophagy in neurodegeneration and neuroprotection. Mol Neurodegener 2009; 4:16. [PMID: 19348680 PMCID: PMC2679749 DOI: 10.1186/1750-1326-4-16] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 04/06/2009] [Indexed: 12/12/2022] Open
Abstract
Autophagy is the major pathway involved in the degradation of proteins and organelles, cellular remodeling, and survival during nutrient starvation. Autophagosomal dysfunction has been implicated in an increasing number of diseases from cancer to bacterial and viral infections and more recently in neurodegeneration. While a decrease in autophagic activity appears to interfere with protein degradation and possibly organelle turnover, increased autophagy has been shown to facilitate the clearance of aggregation-prone proteins and promote neuronal survival in a number of disease models. On the other hand, too much autophagic activity can be detrimental as well and lead to cell death, suggesting the regulation of autophagy has an important role in cell fate decisions. An increasing number of model systems are now available to study the role of autophagy in the central nervous system and how it might be exploited to treat disease. We will review here the current knowledge of autophagy in the central nervous system and provide an overview of the various models that have been used to study acute and chronic neurodegeneration.
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Affiliation(s)
- Philipp A Jaeger
- Geriatric Research Education and Clinical Center, VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, California, USA.
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298
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Cardioprotection requires taking out the trash. Basic Res Cardiol 2009; 104:169-80. [PMID: 19242643 DOI: 10.1007/s00395-009-0011-9] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 01/25/2009] [Accepted: 02/26/2009] [Indexed: 01/08/2023]
Abstract
Autophagy is a critical cellular housekeeping process that is essential for removal of damaged or unwanted organelles and protein aggregates. Under conditions of starvation, it is also a mechanism to break down proteins to generate amino acids for synthesis of new and more urgently needed proteins. In the heart, autophagy is upregulated by starvation, reactive oxygen species, hypoxia, exercise, and ischemic preconditioning, the latter a well-known potent cardioprotective phenomenon. The observation that upregulation of autophagy confers protection against ischemia/reperfusion injury and inhibition of autophagy is associated with a loss of cardioprotection conferred by pharmacological conditioning suggests that the pathway plays a key role in enhancing the heart's tolerance to ischemia. While many of the antecedent signaling pathways of preconditioning are well-defined, the mechanisms by which preconditioning and autophagy converge to protect the heart are unknown. In this review we discuss mechanisms that potentially underlie the linkage between cardioprotection and autophagy in the heart.
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299
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Olanow CW, Kieburtz K, Schapira AHV. Why have we failed to achieve neuroprotection in Parkinson's disease? Ann Neurol 2009; 64 Suppl 2:S101-10. [PMID: 19127580 DOI: 10.1002/ana.21461] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The development of a neuroprotective therapy that slows, stops, or reverses neurodegeneration in Parkinson's disease (PD) is the single most important unresolved issue in the management of this disorder. Current therapies provide effective control of symptoms, particularly in the early stages of the disease, but disease progression is associated with the development of "nondopaminergic" features such as postural instability, falling, and dementia that are not adequately controlled with existing medications. There are many promising candidate neuroprotective agents based on pathological and laboratory studies, but to date, it has not been possible to determine that any drug has a disease-modifying effect in PD. Obstacles to the development of a neuroprotective therapy in PD include: (1) uncertainty as to the precise cause of cell death in PD and what to target; (2) the lack of an animal model of PD that precisely reflects the etiopathogenesis of the disease, the pattern of dopaminergic and nondopaminergic pathology, and its chronic, progressive nature; (3) determination of the correct dose to use in clinical trials; and (4) delineation of a clinical end point that is an accurate measure of the underlying disease and is not confounded by potential symptomatic effects of a study intervention. New developments in understanding the cause of the disease, in the development of animal models of PD, and in clinical trial methodology will hopefully hasten the resolution of these problems.
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Affiliation(s)
- C Warren Olanow
- Department of Neurology, Mount Sinai School of Medicine, New York, USA.
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300
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Golde TE. The therapeutic importance of understanding mechanisms of neuronal cell death in neurodegenerative disease. Mol Neurodegener 2009; 4:8. [PMID: 19193222 PMCID: PMC2644308 DOI: 10.1186/1750-1326-4-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Accepted: 02/04/2009] [Indexed: 01/02/2023] Open
Abstract
Despite major advances in our understanding of the initiating factors that trigger many neurodegenerative disorders, to date, no novel disease-modifying therapies have been shown to provide significant benefit for patients who suffer from these devastating disorders. As most neurodegenerative disorders are late-onset, slowly progressive, and appear to have long relatively asymptomatic prodromal phases, it is possible that therapies optimally targeting the triggers of these disorders may have limited benefit when treatment is initiated in the symptomatic patient. Such therapies may work in the prodromal phase, or when given prophylactically, but in the symptomatic patient there simply may be too much damage to the neuronal networks to restore functionality by reducing or even eliminating the primary stressor. As functional neuronal demise and overt neuronal death are almost certainly the key factors that mediate the functional impairment, it is clear that preventing neuronal death and dysfunction will have a huge clinical benefit. Unfortunately, we lack a detailed understanding of neuronal death pathways in almost all neurodegenerative disorders. To rationally develop new disease modifying therapies that target steps in the degenerative cascade downstream of the disease trigger will require a number of factors. First, we need to refocus our basic research efforts on identifying the precise steps in the pathological cascade that lead to neuronal death in each neurodegenerative disease and, if possible, determine the relative placement of those events within a potentially very complex cascade. Second, we will need to determine which of these steps are potentially targetable. Finally, we will need to develop novel therapies that interfere with these steps and demonstrate that such therapies alone, or in combination with therapies that target the trigger of these devastating diseases, have clinical benefit.
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Affiliation(s)
- Todd E Golde
- Department of Neuroscience, Mayo Clinic, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, Florida 32224, USA.
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