Kegg Pathway: Huntington's disease

Cell Death Differ. 2008 Jul 18;
Sarkar S, Ravikumar B, Floto RA, Rubinsztein DC

The formation of intra-neuronal mutant protein aggregates is a characteristic of several human neurodegenerative disorders, like Alzheimer's disease, Parkinson's disease (PD) and polyglutamine disorders, including Huntington's disease (HD). Autophagy is a major clearance pathway for the removal of mutant huntingtin associated with HD, and many other disease-causing, cytoplasmic, aggregate-prone proteins. Autophagy is negatively regulated by the mammalian target of rapamycin (mTOR) and can be induced in all mammalian cell types by the mTOR inhibitor rapamycin. It can also be induced by a recently described cyclical mTOR-independent pathway, which has multiple drug targets, involving links between Ca(2+)-calpain-G(salpha) and cAMP-Epac-PLC-varepsilon-IP(3) signalling. Both pathways enhance the clearance of mutant huntingtin fragments and attenuate polyglutamine toxicity in cell and animal models. The protective effects of rapamycin in vivo are autophagy-dependent. In Drosophila models of various diseases, the benefits of rapamycin are lost when the expression of different autophagy genes is reduced, implicating that its effects are not mediated by autophagy-independent processes (like mild translation suppression). Also, the mTOR-independent autophagy enhancers have no effects on mutant protein clearance in autophagy-deficient cells. In this review, we describe various drugs and pathways inducing autophagy, which may be potential therapeutic approaches for HD and related conditions.Cell Death and Differentiation advance online publication, 18 July 2008; doi:10.1038/cdd.2008.110.

Stem Cells. 2008 Jul 17;
Sadan O, Shemesh N, Barzilay R, Bahat-Stromza M, Melamed E, Cohen Y, Offen D

Stem cell based treatment is a promising frontier for neurodegenerative diseases. We propose a novel protocol for inducing the differentiation of rat mesenchymal stem cells (MSCs) towards neurotrophic factors (NTFs) secreting cells as a possible neuroprotective agent. One of the major caveats of stem cell transplantation is their fate post transplantation. For that purpose, we tracked the transplanted cells in vivo by MRI scans and validated the results by histology. MSCs went through a two-step medium-based differentiation protocol, followed by in vitro characterization employing immunocytochemistry and immunoblotting analysis of the cells media. We examined the migratory properties of the cells in the quinolinic acid (QA) induced striatal lesion model for Huntington's disease. The induced cells were labeled and transplanted posterior to the lesion. Rats underwent serial MRI scans to detect cell migration in vivo. On the 19th day, animals were sacrificed and their brains were removed for immunostaining. Rat MSCs post induction exhibited both neuronal and astrocyte markers, as well as unregulated production and secretion of NTFs. High resolution 2D and 3D MR images revealed that the cells migrated along a distinct route towards the lesion. The in vivo MRI results were validated by the histological study which demonstrated that phagocytosis had only partially occurred, and that MRI could correctly depict the status of the migrating cells. The results show that these cells migrated towards a QA lesion, and therefore survived for 19 days post transplantation. This gives hope for future research harnessing these cells for treating neurodegenerative diseases. ______________________________________________________________________________ Author contributions: O.S.: Conception and design, collection and assembly of data, data analysis and interpretation and manuscript writing; N.S.: Conception and design, collection and assembly of data, data analysis and interpretation and manuscript writing; R.B.: Collection and assembly of data, data analysis and interpretation; M.B.-S.: Collection and assembly of data, data analysis and interpretation; E.M.: Conception and design, financial support and final approval of the manuscript; Y.C.: Conception and design, financial support and final approval of the manuscript; D.O.: Conception and design, financial support and final approval of the manuscript. Sadan Ofer- and Shemesh Noam contributed equally to this work.

Hum Mol Genet. 2008 Jul 16;
Brown TB, Bogush AI, Ehrlich ME

Huntington's disease (HD) is an autosomal-dominant neurodegenerative disease caused by an expanded polyglutamine tract in the ubiquitously-expressed huntingtin protein. Clinically, HD is characterized by motor, cognitive and psychiatric deficits. Striking degeneration of the striatum is observed in HD with the medium spiny neurons (MSNs) being the most severely affected neuronal subtype. Dysfunction of MSNs is marked by characteristic changes in gene expression which precede neuronal death. The ubiquitous expression of the huntingtin protein raises the question as to whether the selective vulnerability of the MSN is cell-autonomous, non-cell-autonomous, or a combination thereof. In particular, growing evidence suggests that abnormalities of the cortex and corticostriatal projections may be primary causes of striatal vulnerability. To examine this issue, we developed transgenic mice that, within the forebrain, selectively express a pathogenic huntingtin species in the MSNs, specifically excluding the neocortex. These mice develop a number of abnormalities characteristic of pan-cellular HD mouse models, including intranuclear inclusion bodies, motor impairment, and changes in striatal gene expression. As this phenotype develops in the presence of normal levels of brain-derived neurotrophic factor (BDNF) and its major striatal receptor, tropomyosin-related kinase B (trkB), these data represent the first demonstration of in vivo cell-autonomous transcriptional dysregulation in an HD mouse model. Furthermore, our findings suggest that therapies targeted directly to the striatum may be efficacious at reversing some of the molecular abnormalities present in HD.

J Biol Chem. 2008 Jul 16;
Fujikake N, Nagai Y, Popiel HA, Okamoto Y, Yamaguchi M, Toda T

Many neurodegenerative diseases including Alzheimer's, Parkinson's, and the polyglutamine (polyQ) diseases are thought to be caused by protein misfolding. The polyQ diseases, including Huntington's disease (HD) and spinocerebellar ataxias (SCAs), are caused by abnormal expansions of the polyQ stretch in disease-causing proteins, which trigger misfolding of these proteins, resulting in their deposition as inclusion bodies in affected neurons. Although genetic expression of molecular chaperones has been shown to suppress polyQ protein misfolding and neurodegeneration, toward developing a therapy, it is ideal to induce endogenous molecular chaperones by chemical administration. In this study, we assessed the therapeutic effects of heat shock transcription factor 1 (HSF1)-activating compounds, which induce multiple endogenous molecular chaperones, on polyQ-induced neurodegeneration in vivo. We found that oral administration of 17-(Allylamino)-17-demethoxygeldanamycin (17-AAG) markedly suppresses compound eye degeneration accompanied with reduced inclusion bodies in a Drosophila model of SCA. 17-AAG also dramatically rescued the lethality of the SCA model (74.1% rescue), and suppressed neurodegeneration in a HD model (46.3% rescue), indicating that 17-AAG is widely effective against various polyQ diseases. 17-AAG induced Hsp70, Hsp40, and Hsp90 expression in a dose-dependent manner, and the expression levels correlated with its therapeutic effects. Furthermore, knockdown of HSF1 abolished the induction of molecular chaperones and therapeutic effect of 17-AAG, indicating that its therapeutic effects depend on HSF1 activation. Our study indicates that induction of multiple endogenous molecular chaperones by 17-AAG treatment is a promising therapeutic approach for a wide range of polyQ diseases, and possibly other neurodegenerative diseases.

Parkinsonism Relat Disord. 2008 Jul 14;
Gómez-Ansón B, Alegret M, Muñoz E, Monté GC, Alayrach E, Sánchez A, Boada M, Tolosa E

PURPOSE: To investigate grey matter volumes on magnetic resonance imaging (MRI) in preclinical Huntington's disease (HD), and their relationship to neuropsychology and CAG number. MATERIAL AND METHODS: Twenty preclinical HD carriers and 21 healthy controls matched for age, sex, and educational level were included in this study. Clinical (UHDRS), and detailed neuropsychological assessments, and 3D IR SPGR axial MR acquisition. Calculation of global, segmented (SIENAX), and focal (voxel based morphometry, VBM) grey matter volumes was carried out. An analysis of variance (ANOVA) and a general linear model for VBM analysis were used to compare preclinical HD carriers and controls. Small volume correction was used, and clusters at p<0.05 were considered significant. Correlation analysis (VBM) with neuropsychology, and CAG number was also performed. RESULTS: Preclinical HD carriers showed, compared to controls, smaller global volumes of the brain (1279+/-6 vs. 1331+/-46, p=0.003), total (666+/-48 vs. 698+/-34, p=0.020) and cortical grey matter (551+/-44 vs. 577+/-32, p=0.035). When compared to the controls, preclinical carriers showed focal volume losses, which were more prominent in the left prefrontal cortex, cerebellum, and right posterior temporal cortex. Preclinical HD performed slower in a visuomotor integration task, the 15-Objects test, than controls (t (1,25.02)=3.69; p=0.001: pre-HD: 69.55+/-28.86; controls: 45.79+/-8.38). A correlation was found between volume loss in the prefrontal cortex, visuomotor performance, and CAG number. CONCLUSION: Preclinical HD carriers show grey matter volume reduction involving the prefrontal cortex, which relates to the visuomotor performance and CAG number. This suggests that regionally selective neuronal loss/dysfunction occurs prior to the clinical onset of symptoms.

Handb Clin Neurol. 2008; 89: 631-8
Durr A

Handb Clin Neurol. 2008; 89: 619-29
Saudou F, Humbert S

Handb Clin Neurol. 2008; 89: 599-618
Vonsattel JP, Keller C, Pilar Amaya MD

Handb Clin Neurol. 2008; 89: 589-98
Duff K, Beglinger LJ, Paulsen JS

Curr Diab Rep. 2008 Aug; 8(4): 249-50
Sacks FM

Am J Med Genet A. 2008 Jul 14;
Licklederer C, Wolff G, Barth J

Predictive genetic testing for Huntington disease (HD) might cause severe short-term psychological reactions in patients with poor mental health. Very few studies exist on the long-term effects of genetic HD testing. The aim of this study was to assess mental health and quality of life in persons who were tested for HD mutation, to compare mental health depending on the result of the genetic test (non-carriers, gene carriers, and patients with HD) and to identify predictors of mental health and quality of life via linear regression. The data were collected by self-report questionnaires. In total, 121 individuals participated in this study: 52 were non-carriers, 54 were gene carriers, and 15 were gene carriers suffering from HD. Non-carriers and gene carriers showed better mental health and quality of life than HD-patients but did not differ from each other. In non-carriers four variables predicted increased depression and low mental quality of life: low perceived social support, no intimate relationship, female sex and younger age. For gene carriers three predictors were found: low perceived social support, the expectation of an unfavorable genetic test result before the testing procedure and being childless. To prevent detrimental effects of HD testing on mental health and mental quality of life, specific attention should be paid to persons with limited social networks during genetic counseling. Assessment of expectations related to the test result and mental health prior to a genetic testing procedure may help to identify gene carriers at risk of poor coping after an unfavorable test result. (c) 2008 Wiley-Liss, Inc.

Am J Med Genet A. 2008 Jul 14;
Oster E, Dorsey ER, Bausch J, Shinaman A, Kayson E, Oakes D, Shoulson I, Quaid K,

Genetic testing in Huntington disease, an inherited ultimately fatal neurodegenerative disorder, is infrequent despite wide availability. Factors influencing the decision to pursue testing are largely unknown. We conducted a prospective longitudinal observational study of 1,001 individuals in North America who were at risk for Huntington disease who had not pursued genetic testing prior to enrollment. We evaluated the rationale for remaining untested at baseline, determined the concerns of those who eventually pursued testing, and assessed the population's psychological attributes. We contrasted responses between those who did and did not pursue testing, and between United States and Canadian residents. The principal reasons for remaining untested were comfort with risk and uncertainty and the inability to "undo" knowledge gained. After enrollment, 83 individuals [8.3%] pursued genetic testing. Their greatest concern was losing health insurance, and 41.6% of them [vs. 6.7% of those who did not pursue testing; P < 0.001] reported paying out of pocket for testing or other medical services to conceal their genetic risk from their insurer/employer. Among individuals who were tested, more United States residents [46.1%] than Canadian residents [0.0%; P = 0.02] paid out of pocket for health services or genetic testing. Psychological attributes were similar among individuals who did and did not pursue testing. Individuals at risk for Huntington disease who pursued genetic testing feared losing medical insurance, and many paid out of pocket for medical services. Alleviating the fear of health insurance loss may help those who want to pursue genetic testing for many other conditions. [ClinicalTrials.gov number, NCT0052143]. (c) 2008 Wiley-Liss, Inc.

J Exp Med. 2008 Jul 14;
Björkqvist M, Wild EJ, Thiele J, Silvestroni A, Andre R, Lahiri N, Raibon E, Lee RV, Benn CL, Soulet D, Magnusson A, Woodman B, Landles C, Pouladi MA, Hayden MR, Khalili-Shirazi A, Lowdell MW, Brundin P, Bates GP, Leavitt BR, Möller T, Tabrizi SJ

Huntington's disease (HD) is an inherited neurodegenerative disorder characterized by both neurological and systemic abnormalities. We examined the peripheral immune system and found widespread evidence of innate immune activation detectable in plasma throughout the course of HD. Interleukin 6 levels were increased in HD gene carriers with a mean of 16 years before the predicted onset of clinical symptoms. To our knowledge, this is the earliest plasma abnormality identified in HD. Monocytes from HD subjects expressed mutant huntingtin and were pathologically hyperactive in response to stimulation, suggesting that the mutant protein triggers a cell-autonomous immune activation. A similar pattern was seen in macrophages and microglia from HD mouse models, and the cerebrospinal fluid and striatum of HD patients exhibited abnormal immune activation, suggesting that immune dysfunction plays a role in brain pathology. Collectively, our data suggest parallel central nervous system and peripheral pathogenic pathways of immune activation in HD.

Lab Anim. 2008 Jul; 42(3): 277-83
Olsson IA, Hansen AK, Sandøe P

The use of animals in biomedical and other research presents an ethical dilemma: we do not want to lose scientific benefits, nor do we want to cause laboratory animals to suffer. Scientists often refer to the potential human benefits of animal models to justify their use. However, even if this is accepted, it still needs to be argued that the same benefits could not have been achieved with a mitigated impact on animal welfare. Reducing the adverse effects of scientific protocols ('refinement') is therefore crucial in animal-based research. It is especially important that researchers share knowledge on how to avoid causing unnecessary suffering. We have previously demonstrated that even in studies in which animal use leads to spontaneous death, scientists often fail to report measures to minimize animal distress (Olsson et al. 2007). In this paper, we present the full results of a case study examining reports, published in peer-reviewed journals between 2003 and 2004, of experiments employing animal models to study the neurodegenerative disorder Huntington's disease. In 51 references, experiments in which animals were expected to develop motor deficits so severe that they would have difficulty eating and drinking normally were conducted, yet only three references were made to housing adaptation to facilitate food and water intake. Experiments including end-stages of the disease were reported in 14 papers, yet of these only six referred to the euthanasia of moribund animals. If the reference in scientific publications reflects the actual application of refinement, researchers do not follow the 3Rs (replacement, reduction, refinement) principle. While in some cases, it is clear that less-than-optimal techniques were used, we recognize that scientists may apply refinement without referring to it; however, if they do not include such information in publications, it suggests they find it less relevant. Journal publishing policy could play an important role: first, in ensuring that referees seriously consider whether submitted studies were indeed carried out with the smallest achievable negative impact on the animals and, secondly, in encouraging scientists to share refinements through the inclusion of a 3Rs section in papers publishing the results of animal-based research.

Mol Cell Neurosci. 2008 Jun 19;
Lorincz MT, Zawistowski VA

Huntington's disease is an uncommon autosomal dominant neurodegenerative disorder caused by expanded polyglutamine repeats. Increased neurogenesis was demonstrated recently in Huntington's disease post-mortem samples. In this manuscript, neuronally differentiated embryonic stem cells with expanded CAG repeats in the murine Huntington's disease homologue and neural progenitors isolated from the subventricular zone of an accurate mouse Huntington's disease were examined for increased neurogenesis. Embryonic stem cells with expanded CAG repeats in the murine Huntington's disease homologue were demonstrated to undergo facilitated differentiation first into neural progenitors, then into more mature neurons. Neural progenitor cells isolated from the subventricular zone of a Huntington's disease knock-in animal displayed increased production of neural progenitors and increased neurogenesis. These findings suggested that neuronally differentiating embryonic stem cells with expanded CAG repeats is a reasonable system to identify factors responsible for increased neurogenesis in Huntington's disease. Expression profiling analysis comparing neuronally differentiating embryonic stem cells with expanded CAG repeats to neuronally differentiating embryonic stem cells without expanded CAG repeats identified transcripts involved in development and transcriptional regulation as factors possibly mediating increased neurogenesis in response to expanded CAG repeats.

Biochem Biophys Res Commun. 2008 Jul 11;
Almeida S, Sarmento-Ribeiro AB, Januário C, Rego AC, Oliveira CR

The mechanisms by which neurons die in Huntington's disease (HD) are uncertain, however, mitochondrial dysfunction and apoptosis have been implicated. Because peripheral abnormalities may reflect similar consequences of mutant huntingtin in the brain, we evaluated markers of apoptotic cell death and mitochondrial function in peripheral blood cells of 10 HD patients and 16 age- and gender-matched controls. We found increased Bax expression in B and T lymphocytes, and monocytes from HD patients, but no alterations in Bcl-2 expression levels. B lymphocytes also showed decreased mitochondrial membrane potential. However, HD peripheral blood cells showed no differences in reactive oxygen species (ROS) levels when compared to controls. Our results suggest that peripheral blood cells, in particularly B lymphocytes may reflect changes observed in HD brain.

Care Manag J. 2008; 9(2): 63-4
Lechich AJ

J Theor Biol. 2008 May 28;
Banaie M, Sarbaz Y, Gharibzadeh S, Towhidkhah F

Huntington's disease is a movement disorder originated from malfunctioning of Basal Ganglia (BG). There are some models for this disease, most of them being conceptual. So, it seems that considering all physiological information and structural specifications to develop a holistic model is needed. We introduce a computational model based on experimental and physiological findings. Parts of the brain known to be involved in Huntington's disease are all considered in our model and most features of the movement disorders have been appeared in the model. This mathematical model has considered the involved parts of the brain in a fairly accurate way, explaining the behavior and mechanism of the disease according to the physiological information. Our model has several advantages. It is able to simulate the normal and Huntington's disease stride time intervals. It shows how the present treatment, i.e. diazepam, is able to ameliorate the gait disorder. In this research we assessed the effects of changing some neurotransmitter levels in order to propose new treatments. Although we showed that gamma amino butyric acid (GABA) blockers reduce Huntington's disease movement disorder, but we discussed that it is unfair to use this route for treatment. We evaluated our model response to increment of GABA, alone and observed that the gait disorder was strengthened. Our novel idea in this regard is resuscitation of BG loop in order to maintain its major physiological functions, and at the same time raising the threshold in order to weaken the internal disturbances. Our last idea about BG treatment is to decrease glutamate. Our model was able to show the effectiveness of this treatment on Huntington's disease disturbances. We propose that experimental studies should be designed in which these two novel methods of treatment will be evaluated. This validation would implement a milestone in treatment of such a debilitating disease at Huntington.

Care Manag J. 2008; 9(2): 75-81
Klager J, Duckett A, Sandler S, Moskowitz C

This article describes the challenges of end-of-life care encountered in a specialized long-term care program for people with Huntington's disease (HD). The Promoting Excellence in End-of-Life Care Huntington's disease Workgroup defines the initiation of palliative care as the point at which independent living is no longer possible. Mobility and lifestyle accommodations for people in the nursing home setting with an early-onset disease are a major feature of this program. The primary end-of-life considerations are advance directives decision-making and anticipating end-stage care needs. disease progression, denial, family conflict, and clinician blind-spots may impede the development of timely advance directives. The unpredictable and idiosyncratic nature of disease progression impacts decision making for end-of-life care settings and approaches: hospitalization, nursing home stay, and in-house hospice care are the available options. The Workgroup has delineated several priority areas for patient care in HD: autonomy; dignity; meaningful social interaction; communication; comfort; safety and order; spirituality; enjoyment, entertainment and well-being; nutrition; and functional competence. This review also includes a description of the program features in each of these areas.

Care Manag J. 2008; 9(2): 65-74
Lechich AJ, Lovecky D, Moskowitz C, Montas S, Duckett A, Pae A, Knoblauch K, Saks D, Toliver D, Fogarty E, Pollard J

This article describes the contours of the residential care placement experience for social service staff health care providers, and their client families of patients with Huntington's disease. The purpose of this study was to determine the factors, conditions, and barriers encountered by outpatient clinical staff and families in the transition to skilled nursing care. A Long-Term Care Contact Survey was developed to (a) gather information about long-term care referral sites; (b) determine the factors considered in choosing a facility; (c) describe the factors that hindered the transition to long-term care; (d) describe conditions prior to institutionalization; and (e) determine research interest. The study found that large cohorts of patients with Huntington's disease in residential care are scarce. A lack of confidence in the available options suggests the need for increased support for educational and social services to facility staff Speech/swallowing therapy and physical therapy as placement facilitators reflect salient issues of latter stages of the disease, implicating funding support needs. Families facing this transition require long-term guidance for financiail, caregiving, and psychosocial issues.