Asunto(s)
Terapia Genética/efectos adversos , Enfermedad de Huntington/genética , Enfermedad de Huntington/terapia , Oligonucleótidos Antisentido/efectos adversos , Oligonucleótidos Antisentido/uso terapéutico , Oligonucleótidos/efectos adversos , Oligonucleótidos/uso terapéutico , Progresión de la Enfermedad , Femenino , Esperanza , Humanos , Proteína Huntingtina/deficiencia , Proteína Huntingtina/genética , Proteína Huntingtina/metabolismo , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Oligonucleótidos/administración & dosificación , Oligonucleótidos Antisentido/administración & dosificación , Optimismo , Insuficiencia del TratamientoRESUMEN
Huntington's disease is a dominantly inherited, fatal neurodegenerative disorder caused by a CAG expansion in the huntingtin (HTT) gene, coding for pathological mutant HTT protein (mHTT). Because of its gain-of-function mechanism and monogenic aetiology, strategies to lower HTT are being actively investigated as disease-modifying therapies. Most approaches are currently targeted at the manifest stage, where clinical outcomes are used to evaluate the effectiveness of therapy. However, as almost 50% of striatal volume has been lost at the time of onset of clinical manifest, it would be preferable to begin therapy in the premanifest period. An unmet challenge is how to evaluate therapeutic efficacy before the presence of clinical symptoms as outcome measures. To address this, we aim to develop non-invasive sensitive biomarkers that provide insight into therapeutic efficacy in the premanifest stage of Huntington's disease. In this study, we mapped the temporal trajectories of arteriolar cerebral blood volumes (CBVa) using inflow-based vascular-space-occupancy (iVASO) MRI in the heterozygous zQ175 mice, a full-length mHTT expressing and slowly progressing model with a premanifest period as in human Huntington's disease. Significantly elevated CBVa was evident in premanifest zQ175 mice prior to motor deficits and striatal atrophy, recapitulating altered CBVa in human premanifest Huntington's disease. CRISPR/Cas9-mediated non-allele-specific HTT silencing in striatal neurons restored altered CBVa in premanifest zQ175 mice, delayed onset of striatal atrophy, and slowed the progression of motor phenotype and brain pathology. This study-for the first time-shows that a non-invasive functional MRI measure detects therapeutic efficacy in the premanifest stage and demonstrates long-term benefits of a non-allele-selective HTT silencing treatment introduced in the premanifest Huntington's disease.
Asunto(s)
Progresión de la Enfermedad , Silenciador del Gen/fisiología , Proteína Huntingtina/deficiencia , Proteína Huntingtina/genética , Enfermedad de Huntington/diagnóstico por imagen , Enfermedad de Huntington/genética , Animales , Biomarcadores , Femenino , Imagen por Resonancia Magnética/métodos , Masculino , Ratones , Ratones TransgénicosRESUMEN
Motivation is characterized by a willingness to overcome both cognitive and physical effort costs. Impairments in motivation are common in striatal disorders, such as Huntington's disease (HD), but whether these impairments are isolated to particular domains of behavior is controversial. We ask whether HD differentially affects the willingness of individuals to overcome cognitive versus physical effort. We tested 20 individuals with pre-manifest HD and compared their behavior to 20 controls. Across separate trials, participants made choices about how much cognitive or physical effort they were willing to invest for reward. Our key results were that individuals with pre-manifest HD were less willing than controls to invest cognitive effort but were no different in their overall preference for physical effort. These results cannot be explained by group differences in neuropsychological or psychiatric profiles. This dissociation of cognitive- and physical-effort-based decisions provides important evidence for separable, domain-specific mechanisms of motivation.
Asunto(s)
Apatía , Proteína Huntingtina/genética , Enfermedad de Huntington/fisiopatología , Motivación , Esfuerzo Físico , Adulto , Enfermedades Asintomáticas , Estudios de Casos y Controles , Cognición/fisiología , Cuerpo Estriado/metabolismo , Cuerpo Estriado/fisiopatología , Toma de Decisiones , Dopamina/metabolismo , Femenino , Expresión Génica , Humanos , Proteína Huntingtina/deficiencia , Enfermedad de Huntington/genética , Enfermedad de Huntington/psicología , Masculino , Persona de Mediana Edad , Mutación , Pruebas Neuropsicológicas , RecompensaRESUMEN
Huntington's disease (HD) is a monogenetic neurodegenerative disease, which serves as a model of neurodegeneration with protein aggregation. Autophagy has been suggested to possess a great value to tackle protein aggregation toxicity and neurodegenerative diseases. Current studies suggest that autophagy-endolysosomal pathways are critical for HD pathology. Here we review recent advancement in the studies of autophagy and selective autophagy relating HD. Restoration of autophagy flux and enhancement of selective removal of mutant huntingtin/disease-causing protein would be effective approaches towards tackling HD as well as other similar neurodegenerative disorders.
Asunto(s)
Autofagia , Proteína Huntingtina/deficiencia , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/patología , Lisosomas/patología , Animales , Humanos , Lisosomas/metabolismoRESUMEN
Abnormal communication between cerebral cortex and striatum plays a major role in the motor symptoms of Huntington's disease (HD), a neurodegenerative disorder caused by a mutation of the huntingtin gene (mHTT). Because cortex is the main driver of striatal processing, we recorded local field potential (LFP) activity simultaneously in primary motor cortex (M1) and dorsal striatum (DS) in BACHD mice, a full-length HD gene model, and in a conditional BACHD/Emx-1 Cre (BE) model in which mHTT is suppressed in cortical efferents, while mice freely explored a plus-shaped maze beginning at 20 wk of age. Relative to wild-type (WT) controls, BACHD mice were just as active across >40 wk of testing but became progressively less likely to turn into a perpendicular arm as they approached the choice point of the maze, a sign of HD motor inflexibility. BE mice, in contrast, turned as freely as WT throughout testing. Although BE mice did not exactly match WT in LFP activity, the reduction in alpha (8-13 Hz), beta (13-30 Hz), and low-gamma (30-50 Hz) power that occurred in M1 of turning-impaired BACHD mice was reversed. No reversal occurred in DS. In fact, BE mice showed further reductions in DS theta (4-8 Hz), beta, and low-gamma power relative to the BACHD model. Coherence analysis indicated a dysregulation of corticostriatal information flow in both BACHD and BE mice. Collectively, our results suggest that mHTT in cortical outputs drives the dysregulation of select cortical frequencies that accompany the loss of behavioral flexibility in HD.NEW & NOTEWORTHY BACHD mice, a full-length genetic model of Huntington's disease (HD), express aberrant local field potential (LFP) activity in primary motor cortex (M1) along with decreased probability of turning into a perpendicular arm of a plus-shaped maze, a motor inflexibility phenotype. Suppression of the mutant huntingtin gene in cortical output neurons prevents decline in turning and improves alpha, beta, and low-gamma activity in M1. Our results implicate cortical networks in the search for therapeutic strategies to alleviate HD motor signs.
Asunto(s)
Conducta Animal/fisiología , Ondas Encefálicas/fisiología , Proteína Huntingtina/deficiencia , Enfermedad de Huntington/fisiopatología , Aprendizaje por Laberinto/fisiología , Corteza Motora/fisiopatología , Neostriado/fisiopatología , Red Nerviosa/fisiopatología , Animales , Modelos Animales de Enfermedad , Femenino , Masculino , Ratones , Ratones TransgénicosRESUMEN
Deficiency of the sleep-wake cycle can accelerate the progression of Huntington's disease (HD) and exacerbate symptoms making it a target of investigation to better understand the molecular pathology of the disorder. In this study we analyzed sleep defects in a Drosophila model of HD and investigated whether disturbed sleep coincides with alterations in the molecular mechanism controlling circadian rhythm. To analyze sleep defects we recorded the daily activity of flies in 12:12 hours light:dark entrainment and in regard to the underlying molecular mechanism measured circadian "clock" gene expression. In HD flies we observed reduced amount of sleep, sleep fragmentation and prolonged sleep latency. We found changes in gene expression patterns of both transcriptional feedback loops of circadian regulation. We detected prolonged expression of the core feedback loop components period and timeless, whilst the secondary feedback loop member vrille had lower expression rates in general. Our results show that the Drosophila HD model recapitulates most of the sleep related symptoms reported in patients therefore it can be a potential tool to study the molecular background of sleep defects in HD. Altered expression of circadian "clock" genes suggests that disturbed sleep pattern in HD might be the consequence of disturbed circadian regulation.
Asunto(s)
Relojes Circadianos/genética , Proteínas de Drosophila/genética , Drosophila/fisiología , Proteína Huntingtina/genética , Sueño/fisiología , Transcriptoma , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Modelos Animales de Enfermedad , Drosophila/genética , Proteínas de Drosophila/deficiencia , Proteínas de Drosophila/metabolismo , Regulación de la Expresión Génica , Proteína Huntingtina/deficiencia , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/patología , Fenotipo , Sueño/genéticaRESUMEN
Numerous studies have shown that mitochondrial dysfunction contributes to consequential phenotypes of Huntington's disease (HD), a fatal and inherited neurodegenerative disease caused by the expanded CAG repeats in the N-terminus of the huntingtin (Htt) gene. To maintain proper function, mitochondria develop a dedicated protein quality control mechanism by activating a stress response termed the mitochondrial unfolded protein response (UPRmt). Defects in the UPRmt have been linked to aging and are also associated with neurodegenerative diseases. However, little is known about the role of the UPRmt in HD. In this study, we find that ABCB10, a mitochondrial transporter involved in the UPRmt pathway, is downregulated in HD mouse striatal cells, HD patient fibroblasts, and HD R6/2 mice. Deletion of ABCB10 causes increased mitochondrial reactive oxygen species (ROS) production and cell death, whereas overexpression of ABCB10 reduces these aberrant events. Moreover, the mitochondrial chaperone HSP60 and mitochondrial protease Clpp, two well-established markers of the UPRmt, are reduced in the in vitro ABCB10-deficienct HD models. CHOP, a key transcription factor of HSP60 and Clpp, is regulated by ABCB10 in HD mouse striatal cells. Furthermore, we find that mutant huntingtin (mtHtt) inhibits the mtUPR by impairing ABCB10 mRNA stability. These findings demonstrate a suppression of the UPRmt by mtHtt, suggesting that disturbance of mitochondrial protein quality control may contribute to the pathogenesis of HD.
Asunto(s)
Transportadoras de Casetes de Unión a ATP/genética , Proteína Huntingtina/genética , Enfermedad de Huntington/genética , Mitocondrias/genética , ARN Mensajero/genética , Respuesta de Proteína Desplegada , Transportadoras de Casetes de Unión a ATP/metabolismo , Animales , Muerte Celular/genética , Línea Celular , Chaperonina 60/genética , Chaperonina 60/metabolismo , Cuerpo Estriado/metabolismo , Cuerpo Estriado/patología , Endopeptidasa Clp/genética , Endopeptidasa Clp/metabolismo , Fibroblastos/metabolismo , Fibroblastos/patología , Regulación de la Expresión Génica , Humanos , Proteína Huntingtina/deficiencia , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/patología , Ratones , Ratones Transgénicos , Mitocondrias/metabolismo , Mitocondrias/patología , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Mutación , Neuronas/metabolismo , Neuronas/patología , Estabilidad del ARN , ARN Mensajero/metabolismo , Transducción de Señal , Factor de Transcripción CHOP/genética , Factor de Transcripción CHOP/metabolismoRESUMEN
Huntington disease (HD) is an autosomal dominant neurodegenerative disorder caused by a mutation in the huntingtin (HTT) gene which results in progressive neurodegeneration in the striatum, cortex, and eventually most brain areas. Despite being a monogenic disorder, environmental factors influence HD characteristics. Both human and mouse studies suggest that mutant HTT (mHTT) leads to gene expression changes that harbor potential to be modulated by the environment. Yet, the underlying mechanisms integrating environmental cues into the gene regulatory program have remained largely unclear. To better understand gene-environment interactions in the context of mHTT, we employed RNA-seq to examine effects of maternal separation (MS) and environmental enrichment (EE) on striatal gene expression during development of BACHD rats. We integrated our results with striatal consensus modules defined on HTT-CAG length and age-dependent co-expression gene networks to relate the environmental factors with disease progression. While mHTT was the main determinant of expression changes, both MS and EE were capable of modulating these disturbances, resulting in distinctive and in several cases opposing effects of MS and EE on consensus modules. This bivalent response to maternal separation and environmental enrichment may aid in explaining their distinct effects observed on disease phenotypes in animal models of HD and related neurodegenerative disorders.
Asunto(s)
Cuerpo Estriado/patología , Exposición a Riesgos Ambientales , Expresión Génica , Enfermedad de Huntington/patología , Animales , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Perfilación de la Expresión Génica , Redes Reguladoras de Genes , Proteína Huntingtina/deficiencia , Ratones , Ratas , Análisis de Secuencia de ARNRESUMEN
Huntington's disease (HD) is a fatal neurodegenerative disease caused by expansion of CAG repeats in the Huntingtin gene (HTT). Neither its pathogenic mechanisms nor the normal functions of HTT are well understood. To model HD in humans, we engineered a genetic allelic series of isogenic human embryonic stem cell (hESC) lines with graded increases in CAG repeat length. Neural differentiation of these lines unveiled a novel developmental HD phenotype: the appearance of giant multinucleated telencephalic neurons at an abundance directly proportional to CAG repeat length, generated by a chromosomal instability and failed cytokinesis over multiple rounds of DNA replication. We conclude that disrupted neurogenesis during development is an important, unrecognized aspect of HD pathogenesis. To address the function of normal HTT protein we generated HTT+/- and HTT-/- lines. Surprisingly, the same phenotype emerged in HTT-/- but not HTT+/- lines. We conclude that HD is a developmental disorder characterized by chromosomal instability that impairs neurogenesis, and that HD represents a genetic dominant-negative loss of function, contrary to the prevalent gain-of-toxic-function hypothesis. The consequences of developmental alterations should be considered as a new target for HD therapies.
Asunto(s)
Inestabilidad Cromosómica , Proteína Huntingtina/genética , Enfermedad de Huntington/genética , Neurogénesis/genética , Alelos , Diferenciación Celular/genética , Línea Celular , Células Madre Embrionarias/metabolismo , Células Madre Embrionarias/patología , Humanos , Proteína Huntingtina/deficiencia , Proteína Huntingtina/metabolismo , Enfermedad de Huntington/etiología , Enfermedad de Huntington/patología , Modelos Biológicos , Fenotipo , Huso Acromático/patología , Expansión de Repetición de TrinucleótidoRESUMEN
We evaluated the impact of early embryonic deletion of huntingtin (htt) from pyramidal neurons on cortical development, cortical neuron survival and motor behavior, using a cre-loxP strategy to inactivate the mouse htt gene (Hdh) in emx1-expressing cell lineages. Western blot confirmed substantial htt reduction in cerebral cortex of these Emx-httKO mice, with residual cortical htt in all likelihood restricted to cortical interneurons of the subpallial lineage and/or vascular endothelial cells. Despite the loss of htt early in development, cortical lamination was normal, as revealed by layer-specific markers. Cortical volume and neuron abundance were, however, significantly less than normal, and cortical neurons showed reduced brain-derived neurotrophic factor (BDNF) expression and reduced activation of BDNF signaling pathways. Nonetheless, cortical volume and neuron abundance did not show progressive age-related decline in Emx-httKO mice out to 24months. Although striatal neurochemistry was normal, reductions in striatal volume and neuron abundance were seen in Emx-httKO mice, which were again not progressive. Weight maintenance was normal in Emx-httKO mice, but a slight rotarod deficit and persistent hyperactivity were observed throughout the lifespan. Our results show that embryonic deletion of htt from developing pallium does not substantially alter migration of cortical neurons to their correct laminar destinations, but does yield reduced cortical and striatal size and neuron numbers. The Emx-httKO mice were persistently hyperactive, possibly due to defects in corticostriatal development. Importantly, deletion of htt from cortical pyramidal neurons did not yield age-related progressive cortical or striatal pathology.
Asunto(s)
Corteza Cerebral/crecimiento & desarrollo , Corteza Cerebral/metabolismo , Cuerpo Estriado/crecimiento & desarrollo , Cuerpo Estriado/metabolismo , Proteína Huntingtina/deficiencia , Células Piramidales/metabolismo , Animales , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Recuento de Células , Supervivencia Celular/fisiología , Corteza Cerebral/patología , Cuerpo Estriado/patología , Femenino , Proteína Huntingtina/genética , Masculino , Ratones Noqueados , Actividad Motora/fisiología , Células Piramidales/patologíaRESUMEN
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease whose predominant neuropathological signature is the selective loss of medium spiny neurons in the striatum. Despite this selective neuropathology, the mutant protein (huntingtin) is found in virtually every cell so far studied, and, consequently, phenotypes are observed in a wide range of organ systems both inside and outside the central nervous system. We, and others, have suggested that peripheral dysfunction could contribute to the rate of progression of striatal phenotypes of HD. To test this hypothesis, we lowered levels of huntingtin by treating mice with antisense oligonucleotides (ASOs) targeting the murine Huntingtin gene. To study the relationship between peripheral huntingtin levels and striatal HD phenotypes, we utilized a knock-in model of the human HD mutation (the B6.HttQ111/+ mouse). We treated mice with ASOs from 2-10 months of age, a time period over which significant HD-relevant signs progressively develop in the brains of HttQ111/+ mice. Peripheral treatment with ASOs led to persistent reduction of huntingtin protein in peripheral organs, including liver (64% knockdown), brown adipose (66% knockdown), and white adipose tissues (71% knockdown). This reduction was not associated with alterations in the severity of HD-relevant signs in the striatum of HttQ111/+ mice at the end of the study, including transcriptional dysregulation, the accumulation of neuronal intranuclear inclusions, and behavioral changes such as subtle hypoactivity and reduced exploratory drive. These results suggest that the amount of peripheral reduction achieved in the current study does not significantly impact the progression of HD-relevant signs in the central nervous system.
Asunto(s)
Encéfalo/metabolismo , Silenciador del Gen , Proteína Huntingtina/deficiencia , Proteína Huntingtina/genética , Enfermedad de Huntington/genética , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Animales , Conducta Animal , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Enfermedad de Huntington/metabolismo , Enfermedad de Huntington/patología , Hígado/metabolismo , Ratones , FenotipoRESUMEN
The mutation in huntingtin (mHtt) leads to a spectrum of impairments in the developing forebrain of Huntington's disease (HD) mouse models. Whether these developmental alterations are due to loss- or gain-of-function mechanisms and contribute to HD pathogenesis is unknown. We examined the role of selective loss of huntingtin (Htt) function during development on postnatal vulnerability to cell death. We employed mice expressing very low levels of Htt throughout embryonic life to postnatal day 21 (Hdhdâ¢hyp). We demonstrated that Hdhdâ¢hyp mice exhibit: (1) late-life striatal and cortical neuronal degeneration; (2) neurological and skeletal muscle alterations; and (3) white matter tract impairments and axonal degeneration. Hdhdâ¢hyp embryos also exhibited subpallial heterotopias, aberrant striatal maturation and deregulation of gliogenesis. These results indicate that developmental deficits associated with Htt functions render cells present at discrete neural foci increasingly susceptible to cell death, thus implying the potential existence of a loss-of-function developmental component to HD pathogenesis.