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Martin B, Golden E, Keselman A, Stone M, Mattson MP, Egan JM, Maudsley S. Therapeutic perspectives for the treatment of Huntington's disease: treating the whole body. Histol Histopathol 2008; 23:237-50. [PMID: 17999380 PMCID: PMC2657556 DOI: 10.14670/hh-23.237] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Huntington's disease (HD) is a tremendously debilitating disorder that strikes relatively young individuals and progresses rapidly over the next ten to fifteen years inducing a loss of cognitive and motor skills and eventually death occurs. The primary locus of the disorder is a polyglutamine expansion of the protein product of the huntingtin (htt) gene. The htt protein appears to be a scaffolding protein that orchestrates the complex assembly of multiple intracellular proteins involved in multiple processes, including vesicular movement and cell metabolism. The htt protein is ubiquitously expressed in human tissues but the predominance of the interest in the pathology lies in its effects on the central nervous system (CNS). Most of the current therapeutics for HD thus have been targeted at preventing neuronal damage in the CNS, however, a considerable body of evidence has been accumulating to suggest that the maintenance of a healthy nervous system is tightly linked with peripheral physiological health. Therefore treatment of both the peripheral and central pathophysiologies of HD could form the basis of a more effective HD therapeutic strategy.
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Affiliation(s)
- Bronwen Martin
- National Institute on Aging, NIH, Gerontology Research Center, Baltimore, MD 21224, USA
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52
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Sarkar S, Krishna G, Imarisio S, Saiki S, O'Kane CJ, Rubinsztein DC. A rational mechanism for combination treatment of Huntington's disease using lithium and rapamycin. Hum Mol Genet 2007; 17:170-8. [PMID: 17921520 DOI: 10.1093/hmg/ddm294] [Citation(s) in RCA: 254] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Huntington's disease (HD) is caused by a polyglutamine expansion mutation in the huntingtin protein that confers a toxic gain-of-function and causes the protein to become aggregate-prone. Aggregate-prone proteins are cleared by macroautophagy, and upregulating this process by rapamycin, which inhibits the mammalian target of rapamycin (mTOR), attenuates their toxicity in various HD models. Recently, we demonstrated that lithium induces mTOR-independent autophagy by inhibiting inositol monophosphatase (IMPase) and reducing inositol and IP3 levels. Here we show that glycogen synthase kinase-3beta (GSK-3beta), another enzyme inhibited by lithium, has opposite effects. In contrast to IMPase inhibition that enhances autophagy, GSK3beta inhibition attenuates autophagy and mutant huntingtin clearance by activating mTOR. In order to counteract the autophagy inhibitory effects of mTOR activation resulting from lithium treatment, we have used the mTOR inhibitor rapamycin in combination with lithium. This combination enhances macroautophagy by mTOR-independent (IMPase inhibition by lithium) and mTOR-dependent (mTOR inhibition by rapamycin) pathways. We provide proof-of-principle for this rational combination treatment approach in vivo by showing greater protection against neurodegeneration in an HD fly model with TOR inhibition and lithium, or in HD flies treated with rapamycin and lithium, compared with either pathway alone.
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Affiliation(s)
- Sovan Sarkar
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
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53
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Watase K, Gatchel JR, Sun Y, Emamian E, Atkinson R, Richman R, Mizusawa H, Orr HT, Shaw C, Zoghbi HY. Lithium therapy improves neurological function and hippocampal dendritic arborization in a spinocerebellar ataxia type 1 mouse model. PLoS Med 2007; 4:e182. [PMID: 17535104 PMCID: PMC1880853 DOI: 10.1371/journal.pmed.0040182] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2004] [Accepted: 03/30/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited neurodegenerative disorder characterized by progressive motor and cognitive dysfunction. Caused by an expanded polyglutamine tract in ataxin 1 (ATXN1), SCA1 pathogenesis involves a multifactorial process that likely begins with misfolding of ATXN1, which has functional consequences on its interactions, leading to transcriptional dysregulation. Because lithium has been shown to exert neuroprotective effects in a variety of conditions, possibly by affecting gene expression, we tested the efficacy of lithium treatment in a knock-in mouse model of SCA1 (Sca1(154Q/2Q) mice) that replicates many features of the human disease. METHODS AND FINDINGS Sca1(154Q/2Q) mice and their wild-type littermates were fed either regular chow or chow that contained 0.2% lithium carbonate. Dietary lithium carbonate supplementation resulted in improvement of motor coordination, learning, and memory in Sca1(154Q/2Q) mice. Importantly, motor improvement was seen when treatment was initiated both presymptomatically and after symptom onset. Neuropathologically, lithium treatment attenuated the reduction of dendritic branching in mutant hippocampal pyramidal neurons. We also report that lithium treatment restored the levels of isoprenylcysteine carboxyl methyltransferase (Icmt; alternatively, Pccmt), down-regulation of which is an early marker of mutant ATXN1 toxicity. CONCLUSIONS The effect of lithium on a marker altered early in the course of SCA1 pathogenesis, coupled with its positive effect on multiple behavioral measures and hippocampal neuropathology in an authentic disease model, make it an excellent candidate treatment for human SCA1 patients.
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Affiliation(s)
- Kei Watase
- 21st Century COE program on Brain Integration and Its Disorders, Tokyo Medical and Dental University, Tokyo, Japan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jennifer R Gatchel
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Yaling Sun
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Effat Emamian
- Institute of Human Genetics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Richard Atkinson
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ronald Richman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hidehiro Mizusawa
- 21st Century COE program on Brain Integration and Its Disorders, Tokyo Medical and Dental University, Tokyo, Japan
| | - Harry T Orr
- Institute of Human Genetics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Chad Shaw
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Huda Y Zoghbi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, United States of America
- * To whom correspondence should be addressed. E-mail:
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54
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Wood NI, Pallier PN, Wanderer J, Morton AJ. Systemic administration of Congo red does not improve motor or cognitive function in R6/2 mice. Neurobiol Dis 2007; 25:342-53. [PMID: 17095235 DOI: 10.1016/j.nbd.2006.09.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Revised: 09/13/2006] [Accepted: 09/22/2006] [Indexed: 11/17/2022] Open
Abstract
Huntington's disease (HD) is a progressive neurodegenerative disorder for which there is no treatment. Prior to the onset of symptoms, abnormal protein aggregates (inclusions) are found in neurons in humans and R6/2 mice. It has been suggested that the progression of HD can be slowed or prevented by disruption of the aggregation process. In agreement with this, it has been reported that systemic treatment of R6/2 mice with Congo red caused a reduction in numbers of striatal inclusions and an improvement in motor symptoms and survival [Sanchez, I., Mahlke, C., Yuan, J., 2003. Pivotal role of oligomerization in expanded polyglutamine neurodegenerative disorders. Nature 421, 373-379]. Here we attempted to replicate this study. We extended the experiment to include measurement of the effects of Congo red on cognitive function in R6/2 mice. Congo red treatment failed to ameliorate either motor or cognitive deficits in R6/2 mice. We suggest that this is due to the inability of Congo red to cross the blood-brain barrier. Since it does not improve the behavioural deterioration that is a key feature of HD, Congo red is unlikely to be useful as a therapy for HD.
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Affiliation(s)
- Nigel I Wood
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
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55
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Li JY, Popovic N, Brundin P. The use of the R6 transgenic mouse models of Huntington's disease in attempts to develop novel therapeutic strategies. NeuroRx 2006; 2:447-64. [PMID: 16389308 PMCID: PMC1144488 DOI: 10.1602/neurorx.2.3.447] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Huntington's disease (HD) is a genetic neurodegenerative disorder. Since identification of the disease-causing gene in 1993, a number of genetically modified animal models of HD have been generated. The first transgenic mouse models, R6/1 and R6/2 lines, were established 8 years ago. The R6/2 mice have been the best characterized and the most widely used model to study pathogenesis of HD and therapeutic interventions. In the present review, we especially focus on the characteristics of R6 transgenic mouse models and, in greater detail, describe the different therapeutic strategies that have been tested in these mice. We also, at the end, critically assess the relevance of the HD mouse models compared with the human disease and discuss how they can be best used in the future.
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Affiliation(s)
- Jia Yi Li
- Neuronal Survival Unit, Wallenberg Neuroscience Center, Department of Experimental Medical Science, Lund, Sweden.
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56
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Sarkar S, Floto RA, Berger Z, Imarisio S, Cordenier A, Pasco M, Cook LJ, Rubinsztein DC. Lithium induces autophagy by inhibiting inositol monophosphatase. ACTA ACUST UNITED AC 2005; 170:1101-11. [PMID: 16186256 PMCID: PMC2171537 DOI: 10.1083/jcb.200504035] [Citation(s) in RCA: 743] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Macroautophagy is a key pathway for the clearance of aggregate-prone cytosolic proteins. Currently, the only suitable pharmacologic strategy for up-regulating autophagy in mammalian cells is to use rapamycin, which inhibits the mammalian target of rapamycin (mTOR), a negative regulator of autophagy. Here we describe a novel mTOR-independent pathway that regulates autophagy. We show that lithium induces autophagy, and thereby, enhances the clearance of autophagy substrates, like mutant huntingtin and α-synucleins. This effect is not mediated by glycogen synthase kinase 3β inhibition. The autophagy-enhancing properties of lithium were mediated by inhibition of inositol monophosphatase and led to free inositol depletion. This, in turn, decreased myo-inositol-1,4,5-triphosphate (IP3) levels. Our data suggest that the autophagy effect is mediated at the level of (or downstream of) lowered IP3, because it was abrogated by pharmacologic treatments that increased IP3. This novel pharmacologic strategy for autophagy induction is independent of mTOR, and may help treatment of neurodegenerative diseases, like Huntington's disease, where the toxic protein is an autophagy substrate.
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Affiliation(s)
- Sovan Sarkar
- Department of Medical Genetics, University of Cambridge, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge CB2 2XY, England, UK
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57
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Berger Z, Ttofi EK, Michel CH, Pasco MY, Tenant S, Rubinsztein DC, O'Kane CJ. Lithium rescues toxicity of aggregate-prone proteins in Drosophila by perturbing Wnt pathway. Hum Mol Genet 2005; 14:3003-11. [PMID: 16141285 DOI: 10.1093/hmg/ddi331] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We have previously shown that lithium can protect against the polyglutamine toxicity of the Huntington's disease mutation in cell models. Here, we demonstrate for the first time in vivo that lithium can protect against the toxicity caused by aggregate-prone proteins with either polyglutamine or polyalanine expansions in Drosophila. We also show that these protective effects can be partly accounted for by lithium acting through the Wnt/Wg pathway, as a GSK3beta-specific inhibitor and overexpression of dTCF also mediate protective effects. Our data suggest that lithium deserves serious consideration for further studies as a therapeutic for polyglutamine diseases, particularly as it is an established drug that has been used for several decades for chronic treatment of affective disorders.
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Affiliation(s)
- Zdenek Berger
- Department of Medical Genetics, Cambridge Institute for Medical Research, Addenbrooke's Hospital, UK
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58
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Tanaka M, Machida Y, Nukina N. A novel therapeutic strategy for polyglutamine diseases by stabilizing aggregation-prone proteins with small molecules. J Mol Med (Berl) 2005; 83:343-52. [PMID: 15759103 DOI: 10.1007/s00109-004-0632-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Accepted: 11/26/2004] [Indexed: 10/25/2022]
Abstract
Polyglutamine diseases, such as Huntington disease (HD) and spinocerebellar ataxia 1 and 3, are autosomal dominant neurodegenerative disorders. They are caused by CAG trinucleotide repeat expansions that are translated into abnormally long polyglutamine tracts. One of the pathological hallmarks in polyglutamine diseases is the formation of intranuclear inclusions of polyglutamine-containing proteins in the brain. Although causal relationships between polyglutamine aggregation and cellular toxicity are much debated, inhibition of the polyglutamine-mediated protein aggregation may provide treatment options for polyglutamine diseases. However, the extreme insolubility of expanded polyglutamines makes it difficult to prepare polyglutamine-containing proteins on a large scale and to search for aggregation inhibitors by in vitro high-throughput screening. To overcome this we developed a novel in vitro model system for polyglutamine diseases using myoglobin as a host protein. We searched for small molecules that inhibit polyglutamine-mediated aggregation by in vitro screening with a mutant myoglobin containing a 35 polyglutamine repeat. The screening assay revealed that disaccharides have a potential to inhibit polyglutamine-induced protein aggregation and to increase survival in a cellular model of HD. Oral administration of trehalose, the most effective disaccharide in vitro, decreased polyglutamine aggregates in the cerebrum and liver, improved motor dysfunction and extended life span in a transgenic mouse model of HD. In vitro experiments suggest that the beneficial effects of trehalose result from its ability to bind and stabilize polyglutamine-containing proteins. The lack of toxicity and high solubility, coupled with its efficacy upon oral administration, make trehalose promising as a therapeutic drug or lead compound for the treatment of polyglutamine diseases. The stabilization of aggregation-prone proteins with small molecules is an attractive strategy because it can block the initial stage of the disease cascade. In addition, this therapeutic approach could be applied not only to polyglutamine diseases but also to a wide variety of misfolding-induced diseases.
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Affiliation(s)
- Motomasa Tanaka
- Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-city, 351-0198 Saitama, Japan.
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Stolovich M, Lerer T, Bolkier Y, Cohen H, Meyuhas O. Lithium Can Relieve Translational Repression of TOP mRNAs Elicited by Various Blocks along the Cell Cycle in a Glycogen Synthase Kinase-3- and S6-Kinase-independent Manner. J Biol Chem 2005; 280:5336-42. [PMID: 15569665 DOI: 10.1074/jbc.m412434200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
TOP mRNAs are translationally controlled by mitogenic, growth, and nutritional stimuli through a 5'-terminal oligopyrimidine tract. Here we show that LiCl can alleviate the translational repression of these mRNAs when progression through the cell cycle is blocked at G(0), G(1)/S, or G(2)/M phases in different cell lines and by various physiological and chemical means. This derepressive effect of LiCl does not involve resumption of cell division. Unlike its efficient derepressive effect in mitotically arrested cells, LiCl alleviates inefficiently the repression of TOP mRNAs in amino acid-deprived cells and has no effect in lymphoblastoids whose TOP mRNAs are constitutively repressed even when they are proliferating. LiCl is widely used as a relatively selective inhibitor of glycogen synthase kinase-3. However, inhibition per se of this enzyme by more specific drugs failed to derepress the translation of TOP mRNAs, implying that relief of the translational repression of TOP mRNAs by LiCl is carried out in a glycogen synthase kinase-3-independent manner. Moreover, this effect is apparent, at least in some cell lines, in the absence of S6-kinase 1 activation and ribosomal protein S6 phosphorylation, thus further supporting the notion that translational control of TOP mRNAs does not rely on either of these variables.
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Affiliation(s)
- Miri Stolovich
- Department of Biochemistry, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
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Stack EC, Kubilus JK, Smith K, Cormier K, Del Signore SJ, Guelin E, Ryu H, Hersch SM, Ferrante RJ. Chronology of behavioral symptoms and neuropathological sequela in R6/2 Huntington's disease transgenic mice. J Comp Neurol 2005; 490:354-70. [PMID: 16127709 DOI: 10.1002/cne.20680] [Citation(s) in RCA: 193] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Genetic murine models play an important role in the study of human neurological disorders by providing accurate and experimentally accessible systems to study pathogenesis and to test potential therapeutic treatments. One of the most widely employed models of Huntington's disease (HD) is the R6/2 transgenic mouse. To characterize this model further, we have performed behavioral and neuropathological analyses that provide a foundation for the use of R6/2 mice in preclinical therapeutic trials. Behavioral analyses of the R6/2 mouse reveal age-related impairments in dystonic movements, motor performance, grip strength, and body weight that progressively worsen until death. Significant neuropathological sequela, identified as increasing marked reductions in brain weight, are present from 30 days, whereas decreased brain volume is present from 60 days and decreased neostriatal volume and striatal neuron area, with a concomitant reduction in striatal neuron number, are present at 90 days of age. Huntingtin-positive aggregates are present at postnatal day 1 and increase in number and size with age. Our findings suggest that the R6/2 HD model exhibits a progressive HD-like behavioral and neuropathological phenotype that more closely corresponds to human HD than previously believed, providing further assurance that the R6/2 mouse is an appropriate model for testing potential therapies for HD.
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Affiliation(s)
- Edward C Stack
- Geriatric Research Education and Clinical Center, Bedford Veterans Administration Medical Center, Bedford, Massachusetts 01730, USA
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61
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Beal MF, Ferrante RJ. Experimental therapeutics in transgenic mouse models of Huntington's disease. Nat Rev Neurosci 2004; 5:373-84. [PMID: 15100720 DOI: 10.1038/nrn1386] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- M Flint Beal
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, Room F610, 525 East 68th Street, New York, NY 10021, USA.
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