RESUMEN
Substantia nigra (SN) hyperechogenicity can be detected by transcranial sonography (TCS) to assist the early diagnosis of idiopathic Parkinson's disease (IPD). This study prospectively investigated whether SN hyperechogenicity is also present in Huntington's disease (HD) patients with symptoms of hypokinesia and/or rigidity. All patients recruited to the study (n = 15) were characterised by hypokinesia and/or rigidity while nine of these patients also displayed chorea and/or dystonia. The control group included 15 individuals. Clinical examination was documented using the Unified Huntington's Disease Rating Scale (UHDRS). TCS examination revealed SN hyperechogenicity in 14/15 (93.3 %) patients (9/14 unilateral, 5/14 bilateral). Hyperechogenicity of the caudate and lentiform nuclei (CN, LN) was less frequent (CN: 80 % total, LN: 53.3 % total). This is the first study to assess SN hyperechogenicity in hypokinetic HD patients. Assuming that the primary sites of pathology in IPD and HD are the SN and the striatum, respectively, our observations suggest a functional impairment of the nigrostriatal system in HD, an effect that is potentially independent of the primarily-affected basal ganglia nucleus.
Asunto(s)
Enfermedad de Huntington/complicaciones , Enfermedad de Huntington/patología , Hipocinesia/complicaciones , Sustancia Negra/diagnóstico por imagen , Adulto , Anciano , Análisis de Varianza , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedad de Parkinson/patología , Estudios Prospectivos , Índice de Severidad de la Enfermedad , Ultrasonografía Doppler Transcraneal , Adulto JovenRESUMEN
One pathway regulating the migration of neurons during development of the mammalian cortex involves the extracellular matrix protein Reelin. Reelin and components of its signaling cascade, the lipoprotein receptors ApoER2 and Vldlr and the intracellular adapter protein Dab1 are pivotal for a correct layer formation during corticogenesis. The olfactory bulb (OB) as a phylogenetically old cortical region is known to be a prominent site of Reelin expression. Although some aspects of Reelin function in the OB have been described, the influence of Reelin on OB layer formation has so far been poorly analyzed. Here we studied animals deficient for either Reelin, Vldlr, ApoER2 or Dab1 as well as double-null mutants. We performed organotypic migration assays, immunohistochemical marker analysis and BrdU incorporation studies to elucidate roles for the different components of the Reelin signaling cascade in OB neuroblast migration and layer formation. We identified ApoER2 as being the main receptor responsible for Reelin mediated detachment of neuroblasts and correct migration of early generated interneurons within the OB, a prerequisite for correct OB lamination.
Asunto(s)
Moléculas de Adhesión Celular Neuronal/metabolismo , Proteínas de la Matriz Extracelular/metabolismo , Proteínas Relacionadas con Receptor de LDL/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Bulbo Olfatorio/citología , Bulbo Olfatorio/metabolismo , Receptores de LDL/metabolismo , Serina Endopeptidasas/metabolismo , Animales , Moléculas de Adhesión Celular Neuronal/genética , Movimiento Celular/genética , Movimiento Celular/fisiología , Proteínas de la Matriz Extracelular/genética , Immunoblotting , Inmunohistoquímica , Hibridación in Situ , Proteínas Relacionadas con Receptor de LDL/genética , Ratones , Ratones Noqueados , Proteínas del Tejido Nervioso/genética , Prosencéfalo/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptores de LDL/genética , Proteína Reelina , Serina Endopeptidasas/genética , Transducción de Señal/genética , Transducción de Señal/fisiologíaRESUMEN
Polyglutamine (PolyQ) diseases have common features that include progressive selective neurodegeneration and the formation of protein aggregates. There is growing evidence to suggest that critical nuclear events lead to transcriptional alterations in PolyQ diseases such as spinocerebellar ataxia type 7 (SCA7) and Huntington's disease (HD), conditions which share a cerebellar degenerative phenotype. Taking advantage of laser capture microdissection technique, we compared the Purkinje cell (PC) gene expression profiles of two transgenic polyQ mouse models (HD: R6/2; SCA7: P7E) by microarray analysis that was validated by real time quantitative PCR. A large number of transcriptional alterations were detected in the R6/2 transgenic model of HD. Similar decreases in the same mRNAs, such as phospholipase C, ß 3, purkinje cell protein 2 (Pcp2) and aldolase C, were found in both models. A decrease in aldolase C and phospholipase C, ß 3, may lead to an increase in the vulnerability of PCs to excitotoxic events. Furthermore, downregulation of mRNAs mediated by the Pcp2-promoter is common in both models. Thus, our data reveal shared molecular abnormalities in different polyQ disorders.
Asunto(s)
Enfermedad de Huntington/genética , Proteínas del Tejido Nervioso/genética , Péptidos/genética , Células de Purkinje/fisiología , Ataxias Espinocerebelosas/genética , Animales , Ataxina-7 , Modelos Animales de Enfermedad , Femenino , Factores de Intercambio de Guanina Nucleótido/genética , Humanos , Proteína Huntingtina , Enfermedad de Huntington/patología , Ratones , Ratones Transgénicos , Neuropéptidos/genética , Análisis de Secuencia por Matrices de Oligonucleótidos , Regiones Promotoras Genéticas/genética , Células de Purkinje/patología , Ataxias Espinocerebelosas/patología , Transcriptoma , Transgenes/genéticaRESUMEN
Ataxia is a clinical feature of most polyglutamine disorders. Cerebellar neurodegeneration of Purkinje cells (PCs) in Huntington's Disease (HD) brain was described in the 1980s. PC death in the R6/2 transgenic model for HD was published by Turmaine et al. So far, PCs have not been examined on a single cell level. In order to begin to understand PC dysfunction and degeneration in HD we performed a gene expression study on laser-dissected PC based on a DNA microarray screening and quantitative real time PCR (Q-PCR). We demonstrate downregulation of the retinoid acid receptor-related orphan receptor (ROR) mRNA and ROR-mediated mRNAs, also seen by immunofluorescent staining. As ROR and ROR-dependent transcriptional dysregulation is not only found in the R6/2 model for HD but also in a model for spinocerebellar ataxia type 1 (SCA1) (Serra et al.) the data suggest common pathogenic mechanisms for both polyglutamine diseases.
Asunto(s)
Enfermedad de Huntington/genética , Miembro 1 del Grupo F de la Subfamilia 1 de Receptores Nucleares/genética , Células de Purkinje/citología , Células de Purkinje/metabolismo , Animales , Cerebelo/metabolismo , Cerebelo/patología , Modelos Animales de Enfermedad , Regulación hacia Abajo , Femenino , Enfermedad de Huntington/metabolismo , Ratones , Ratones Transgénicos , Miembro 1 del Grupo F de la Subfamilia 1 de Receptores Nucleares/metabolismo , ARN Mensajero/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Ataxias Espinocerebelosas/genética , Ataxias Espinocerebelosas/metabolismoRESUMEN
Motor dysfunction, cognitive impairment, and regional cortical atrophy indicate cerebral cortical involvement in Huntington disease (HD). To address the hypothesis that abnormal corticostriatal connectivity arises from polyglutamine-related alterations in cortical gene expression, we isolated layer 5 cortical neurons by laser-capture microdissection and analyzed transcriptome-wide mRNA changes in them. Enrichment of transcription factor mRNAs including foxp2, tbr1, and neuroD6, and neurotransmission- and plasticity-related RNAs including sema5A, pclo, ntrk2, cntn1, and Lin7b were observed. Layer 5 motor cortex neurons of transgenic R6/2 HD mice also demonstrated numerous transcriptomic changes, including decreased expression of mRNAs encoding the Lin7 homolog b ([Lin7b] also known as veli-2 and mals2). Decreases in LIN7B and CNTN1 RNAs were also detected in human HD layer 5 motor cortex neurons. Lin7 homolog b, a scaffold protein implicated in synaptic plasticity, neurite outgrowth, and cellular polarity, was decreased at the protein level in layer 5 cortical neurons in R6/2 mice and human HD brains. Decreases in Lin7b and Lin7a mRNAs were detected in R6/2 cortex as early as 6 weeks of age, suggesting that this is an early pathogenetic event. Thus, decreased cortical LIN7 expression may contribute to abnormal corticostriatal connectivity in HD.
Asunto(s)
Corteza Cerebral , Enfermedad de Huntington , Proteínas de la Membrana/metabolismo , Vías Nerviosas , Neuronas , Proteínas de Transporte Vesicular/metabolismo , Animales , Corteza Cerebral/citología , Corteza Cerebral/patología , Corteza Cerebral/fisiología , Femenino , Humanos , Enfermedad de Huntington/patología , Enfermedad de Huntington/fisiopatología , Proteínas de la Membrana/genética , Ratones , Ratones Transgénicos , Análisis por Micromatrices , Vías Nerviosas/patología , Vías Nerviosas/fisiopatología , Neuronas/citología , Neuronas/metabolismo , Transmisión Sináptica/fisiología , Proteínas de Transporte Vesicular/genéticaRESUMEN
Interactions between mutant huntingtin (Htt) and a variety of transcription factors including specificity proteins (Sp) have been suggested as a central mechanism in Huntington disease (HD). However, the transcriptional activity induced by Htt in neurons that triggers neuronal death has yet to be fully elucidated. In the current study, we characterized the relationship of Sp1 to Htt protein aggregation and neuronal cell death. We found increased levels of Sp1 in neuronal-like PC12 cells expressing mutant Htt, primary striatal neurons, and brain tissue of HD transgenic mice. Sp1 levels were also elevated when 3-nitropropionate (3-NP) was used to induce cell death in PC12 cells. To assess the effects of knocking down Sp1 in HD pathology, we used Sp1 siRNA, a heterozygous Sp1 knock-out mouse, and mithramycin A, a DNA-intercalating agent that inhibits Sp1 function. The three approaches consistently yielded reduced levels of Sp1 which ameliorated toxicity caused by either mutant Htt or 3-NP. In addition, when HD mice were crossed with Sp1 heterozygous knock-out mice, the resulting offspring did not experience the loss of dopamine D2 receptor mRNA characteristic of HD mice, and survived longer than their HD counterparts. Our data suggest that enhancement of transcription factor Sp1 contributes to the pathology of HD and demonstrates that its suppression is beneficial.
Asunto(s)
Enfermedad de Huntington/genética , Fármacos Neuroprotectores/farmacología , Factor de Transcripción Sp1/biosíntesis , Factor de Transcripción Sp1/fisiología , Regulación hacia Arriba , Animales , Modelos Animales de Enfermedad , Femenino , Enfermedad de Huntington/metabolismo , Masculino , Ratones , Ratones Transgénicos , Neuronas/metabolismo , Células PC12 , RatasRESUMEN
Transcriptional dysregulation has been described as a central mechanism in the pathogenesis of Huntington's disease (HD), in which medium spiny projection neurons (MSN) selectively degenerate whereas neuronal nitric-oxide-synthase-positive interneurons (nNOS-IN) survive. In order to begin to understand this differential vulnerability we compared mRNA levels of selected genes involved in N-methyl-D-aspartate (NMDA) glutamate receptor and calcium (Ca2+) signaling pathways in MSN and nNOS-IN from 12-week-old R6/2 mice, a transgenic mouse model of HD and wild-type littermates. We undertook a laser capture microdissection (LCM) study to examine the contribution of transcriptional dysregulation in candidate genes involved in these two signaling pathways in discrete populations of striatal neurons. The use of LCM in combination with quantitative real-time polymerase chain reaction (Q-PCR) allowed us to quantify the neuronal abundance of candidate mRNAs. We found different transcriptional alterations in R6/2 neurons for both MSN and nNOS-IN, indicating that global transcriptional dysregulation alone does not account for selective vulnerability. Further, we observed a striking enrichment of several mRNAs in the nNOS-IN population, including that for the NMDA receptor subunit NR2D, the postsynaptic density protein 95 (PSD-95) and the huntingtin-associated protein 1 (HAP1) as well as nitric-oxide-synthase (nNOS) mRNA itself. The higher expression levels of these molecules in nNOS-IN when compared with MSN together with an association of nNOS, NR2D and HAP1 in a protein complex with PSD-95 suggest that these proteins may be involved in protective pathways that contribute to the resistance of this interneuron population to neurodegeneration in HD.
Asunto(s)
Enfermedad de Huntington/metabolismo , Interneuronas/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Transcripción Genética/fisiología , Animales , Modelos Animales de Enfermedad , Homólogo 4 de la Proteína Discs Large , Guanilato-Quinasas , Péptidos y Proteínas de Señalización Intracelular , Proteínas de la Membrana , Ratones , Proteínas del Tejido Nervioso/genética , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa de Tipo I , Receptores de N-Metil-D-Aspartato/metabolismoRESUMEN
Cystamine, a small disulfide-containing chemical, is neuroprotective in a transgenic mouse and a Drosophila model of Huntington's disease (HD) and decreases huntingtin aggregates in an in vitro model of HD. The mechanism of action of cystamine in these models is widely thought to involve inhibition of transglutaminase mediated cross-linking of mutant huntingtin in the process of aggregate formation/stabilization. In this study we show that cystamine, both in vitro and in a transgenic mouse model of HD (R6/2), increases levels of the cellular antioxidant L-cysteine. Several oxidative stress markers increase in HD brain. We provide further evidence of oxidative stress in mouse HD by demonstrating compensatory responses in R6/2 HD brains. We found age-dependent increases in forebrain glutathione (GSH), and increased levels of transcripts coding for proteins involved in GSH synthesis and detoxification pathways, as revealed by quantitative PCR analysis. Given the general importance of oxidative stress as a mediator of neurodegeneration we propose that an increase in brain L-cysteine levels could be protective in HD. Furthermore, cystamine was dramatically protective against 3-nitropropionic acid-induced striatal injury in mice. We suggest that cystamine's neuroprotective effect in HD transgenic mice results from pleiotropic effects that include transglutaminase inhibition and antioxidant activity.
Asunto(s)
Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Cistamina/farmacología , Cisteína/metabolismo , Enfermedad de Huntington/metabolismo , Péptidos/metabolismo , Animales , Antioxidantes/metabolismo , Antioxidantes/farmacología , Encéfalo/patología , Butionina Sulfoximina/farmacología , Citoprotección/efectos de los fármacos , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Inhibidores Enzimáticos/farmacología , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Glutatión/antagonistas & inhibidores , Glutatión/metabolismo , Humanos , Enfermedad de Huntington/genética , Enfermedad de Huntington/patología , Masculino , Ratones , Ratones Transgénicos , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Neuronas/patología , Fármacos Neuroprotectores/farmacología , Estrés Oxidativo/efectos de los fármacos , Células PC12 , Péptidos/genética , RatasRESUMEN
Gabapentin (GBP), an anti-convulsant widely used in the treatment of neuropathic pain syndromes, has been suggested to have neuroprotective properties. There is evidence, however, that the neuroprotective properties attributed to GBP are rather associated with a derivative of GBP, gabapentin-lactam (GBP-L), which opens mitochondrial ATP-dependent K+ channels, in contrast to GBP. We explored whether GBP and GBP-L may attenuate the course of a monogenetic autosomal neurodegenerative disorder, Huntington's disease (HD), using a transgenic mouse model. R6/2 mice treated with GBP-L performed walking on a narrow beam better than mice receiving no treatment, vehicle or GBP, suggesting a beneficial effect of GBP-L on motor function. In addition, a marked reduction of neuronal nuclear and cytoplasmic inclusions was observed in brains of mice treated with GBP-L. The pharmacokinetics of GBP-L yielded a mean plasma concentration near the EC50 of GBP-L to open mitochondrial ATP-dependent K+ channels. These findings support the role of GBP-L as a novel neuroprotective substance in vivo.
Asunto(s)
Aminas/uso terapéutico , Anticonvulsivantes/uso terapéutico , Compuestos Aza/uso terapéutico , Ácidos Ciclohexanocarboxílicos/uso terapéutico , Enfermedad de Huntington/tratamiento farmacológico , Actividad Motora/efectos de los fármacos , Fármacos Neuroprotectores/uso terapéutico , Compuestos de Espiro/uso terapéutico , Ácido gamma-Aminobutírico/uso terapéutico , Animales , Compuestos Aza/sangre , Compuestos Aza/farmacocinética , Cuerpo Estriado/metabolismo , Cuerpo Estriado/patología , Modelos Animales de Enfermedad , Femenino , Gabapentina , Hipocampo/metabolismo , Hipocampo/patología , Enfermedad de Huntington/patología , Enfermedad de Huntington/fisiopatología , Inyecciones Subcutáneas , Masculino , Ratones , Ratones Transgénicos , Compuestos de Espiro/sangre , Compuestos de Espiro/farmacocinética , Tasa de SupervivenciaRESUMEN
The precise cause of neuronal death in Huntington's disease (HD) is unknown. Although no single specific protein-protein interaction of mutant huntingtin has emerged as the pathologic trigger, transcriptional dysfunction may contribute to the neurodegeneration observed in HD. Pharmacological treatment using the histone deacetylase inhibitor sodium butyrate to modulate transcription significantly extended survival in a dose-dependent manner, improved body weight and motor performance, and delayed the neuropathological sequelae in the R6/2 transgenic mouse model of HD. Sodium butyrate also increased histone and Specificity protein-1 acetylation and protected against 3-nitropropionic acid neurotoxicity. Microarray analysis showed increased expression of alpha- and beta-globins and MAP kinase phosphatase-1 in sodium butyrate-treated R6/2 mice, indicative of improved oxidative phosphorylation and transcriptional regulation. These findings strengthen the hypothesis that transcriptional dysfunction plays a role in the pathogenesis of HD and suggest that therapies aimed at modulating transcription may target early pathological events and provide clinical benefits to HD patients.