RESUMEN
Spinocerebellar ataxia type 3 (SCA3) is the most common type of disease related to poly-glutamine (polyQ) repeats. Its hallmark pathology is related to the abnormal accumulation of ataxin 3 with a longer polyQ tract (polyQ-ATXN3). However, there are other mechanisms related to SCA3 progression that require identifying trait and state biomarkers for a more accurate diagnosis and prognosis. Moreover, the identification of potential pharmacodynamic targets and assessment of therapeutic efficacy necessitates valid biomarker profiles. The aim of this review was to identify potential trait and state biomarkers and their potential value in clinical trials. Our results show that, in SCA3, there are different fluid biomarkers involved in neurodegeneration, oxidative stress, metabolism, miRNA and novel genes. However, neurofilament light chain NfL and polyQ-ATXN3 stand out as the most prevalent in body fluids and SCA3 stages. A heterogeneity analysis of NfL revealed that it may be a valuable state biomarker, particularly when measured in plasma. Nonetheless, since it could be a more beneficial approach to tracking SCA3 progression and clinical trial efficacy, it is more convenient to perform a biomarker profile evaluation than to rely on only one.
Asunto(s)
Biomarcadores , Enfermedad de Machado-Joseph , Humanos , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/metabolismo , Enfermedad de Machado-Joseph/patología , Ataxina-3/genética , Ataxina-3/metabolismo , Proteínas de Neurofilamentos/metabolismo , Péptidos/metabolismo , Progresión de la Enfermedad , Estrés OxidativoRESUMEN
Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative spinocerebellar ataxia caused by a polyglutamine-coding CAG repeat expansion in the ATXN3 gene. While the CAG length correlates negatively with the age at onset, it accounts for approximately 50% of its variability only. Despite larger efforts in identifying contributing genetic factors, candidate genes with a robust and plausible impact on the molecular pathogenesis of MJD are scarce. Therefore, we analysed missense single nucleotide polymorphism variants in the PRKN gene encoding the Parkinson's disease-associated E3 ubiquitin ligase parkin, which is a well-described interaction partner of the MJD protein ataxin-3, a deubiquitinase. By performing a correlation analysis in the to-date largest MJD cohort of more than 900 individuals, we identified the V380L variant as a relevant factor, decreasing the age at onset by 3 years in homozygous carriers. Functional analysis in an MJD cell model demonstrated that parkin V380L did not modulate soluble or aggregate levels of ataxin-3 but reduced the interaction of the two proteins. Moreover, the presence of parkin V380L interfered with the execution of mitophagy-the autophagic removal of surplus or damaged mitochondria-thereby compromising cell viability. In summary, we identified the V380L variant in parkin as a genetic modifier of MJD, with negative repercussions on its molecular pathogenesis and disease age at onset.
Asunto(s)
Enfermedad de Machado-Joseph , Mitofagia , Ubiquitina-Proteína Ligasas , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/patología , Humanos , Ubiquitina-Proteína Ligasas/genética , Mitofagia/genética , Mitofagia/fisiología , Masculino , Femenino , Persona de Mediana Edad , Adulto , Polimorfismo de Nucleótido Simple , Ataxina-3/genética , Edad de Inicio , Proteínas RepresorasRESUMEN
We aimed to produce a mouse model of spinocerebellar ataxia type 3 (SCA3) using the mouse blood-brain barrier (BBB)-penetrating adeno-associated virus (AAV)-PHP.B. Four-to-five-week-old C57BL/6 mice received injections of high-dose (2.0 × 1011 vg/mouse) or low-dose (5.0 × 1010 vg/mouse) AAV-PHP.B encoding a SCA3 causative gene containing abnormally long 89 CAG repeats [ATXN3(Q89)] under the control of the ubiquitous chicken ß-actin hybrid (CBh) promoter. Control mice received high doses of AAV-PHP.B encoding ATXN3 with non-pathogenic 15 CAG repeats [ATXN3(Q15)] or phosphate-buffered saline (PBS) alone. More than half of the mice injected with high doses of AAV-PHP.B encoding ATXN3(Q89) died within 4 weeks after the injection. No mice in other groups died during the 12-week observation period. Mice injected with low doses of AAV-PHP.B encoding ATXN3(Q89) exhibited progressive motor uncoordination starting 4 weeks and a shorter stride in footprint analysis performed at 12 weeks post-AAV injection. Immunohistochemistry showed thinning of the molecular layer and the formation of nuclear inclusions in Purkinje cells from mice injected with low doses of AAV-PHP.B encoding ATXN3(Q89). Moreover, ATXN3(Q89) expression significantly reduced the number of large projection neurons in the cerebellar nuclei to one third of that observed in mice expressing ATXN3(Q15). This AAV-based approach is superior to conventional methods in that the required number of model mice can be created simply by injecting AAV, and the expression levels of the responsible gene can be adjusted by changing the amount of AAV injected. Moreover, this method may be applied to produce SCA3 models in non-human primates.
Asunto(s)
Ataxina-3 , Dependovirus , Modelos Animales de Enfermedad , Vectores Genéticos , Enfermedad de Machado-Joseph , Ratones Endogámicos C57BL , Animales , Dependovirus/genética , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/terapia , Enfermedad de Machado-Joseph/metabolismo , Enfermedad de Machado-Joseph/patología , Ratones , Vectores Genéticos/administración & dosificación , Vectores Genéticos/genética , Ataxina-3/genética , Ataxina-3/metabolismo , Inyecciones Intravenosas , Barrera Hematoencefálica/metabolismo , Regiones Promotoras GenéticasRESUMEN
AIMS: Spinocerebellar Ataxia Type 3 (SCA3) is a rare genetic ataxia that impacts the entire brain and is characterized as a neurodegenerative disorder affecting the neural network. This study explores how alterations in the functional hierarchy, connectivity, and structural changes within specific brain regions significantly contribute to the heterogeneity of symptom manifestations in patients with SCA3. METHODS: We prospectively recruited 51 patients with SCA3 and 59 age-and sex-matched healthy controls. All participants underwent comprehensive multimodal neuroimaging and clinical assessments. In SCA3 patients, an innovative approach utilizing gradients in resting-state functional connectivity (FC) was employed to examine atypical patterns of hierarchical processing topology from sensorimotor to supramodal regions in the cerebellum and cerebrum. Coupling analyses of abnormal FC and structural connectivity among regions of interest (ROIs) in the brain were also performed to characterize connectivity alterations. Additionally, relationships between quantitative ROI values and clinical variables were explored. RESULTS: Patients with SCA3 exhibited either compression or expansion within the primary sensorimotor-to-supramodal gradient through four distinct calculation methods, along with disruptions in FC and structural connectivity coupling. A comprehensive correlation was identified between the altered gradients and the clinical manifestations observed in patients. Notably, altered fractional anisotropy values were not significantly correlated with clinical variables. CONCLUSION: Abnormal gradients and connectivity in the cerebellar and cerebral cortices in SCA3 patients may contribute to disrupted motor-to-supramodal functions. Moreover, these findings support the potential utility of FCG analysis as a biomarker for diagnosing SCA3 and assessing treatment efficacy.
Asunto(s)
Enfermedad de Machado-Joseph , Imagen por Resonancia Magnética , Humanos , Femenino , Masculino , Enfermedad de Machado-Joseph/fisiopatología , Enfermedad de Machado-Joseph/diagnóstico por imagen , Enfermedad de Machado-Joseph/complicaciones , Enfermedad de Machado-Joseph/patología , Persona de Mediana Edad , Adulto , Imagen por Resonancia Magnética/métodos , Encéfalo/diagnóstico por imagen , Encéfalo/fisiopatología , Encéfalo/patología , Vías Nerviosas/fisiopatología , Vías Nerviosas/diagnóstico por imagen , Estudios Prospectivos , Red Nerviosa/diagnóstico por imagen , Red Nerviosa/fisiopatología , Red Nerviosa/patología , Imagen de Difusión Tensora/métodosRESUMEN
Aggregation of aberrant proteins is a common pathological hallmark in neurodegeneration such as polyglutamine (polyQ) and other repeat-expansion diseases. Here through overexpression of ataxin3 C-terminal polyQ expansion in Drosophila gut enterocytes, we generated an intestinal obstruction model of spinocerebellar ataxia type3 (SCA3) and reported a new role of nuclear-associated endosomes (NAEs)-the delivery of polyQ to the nucleoplasm. In this model, accompanied by the prominently increased RAB5-positive NAEs are abundant nucleoplasmic reticulum enriched with polyQ, abnormal nuclear envelope invagination, significantly reduced endoplasmic reticulum, indicating dysfunctional nucleocytoplasmic trafficking and impaired endomembrane organization. Consistently, Rab5 but not Rab7 RNAi further decreased polyQ-related NAEs, inhibited endomembrane disorganization, and alleviated disease model. Interestingly, autophagic proteins were enriched in polyQ-related NAEs and played non-canonical autophagic roles as genetic manipulation of autophagic molecules exhibited differential impacts on NAEs and SCA3 toxicity. Namely, the down-regulation of Atg1 or Atg12 mitigated while Atg5 RNAi aggravated the disease phenotypes both in Drosophila intestines and compound eyes. Our findings, therefore, provide new mechanistic insights and underscore the fundamental roles of endosome-centered nucleocytoplasmic trafficking and homeostatic endomembrane allocation in the pathogenesis of polyQ diseases.
Asunto(s)
Autofagia , Endosomas , Péptidos , Animales , Péptidos/metabolismo , Endosomas/metabolismo , Núcleo Celular/metabolismo , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Transporte Activo de Núcleo Celular , Drosophila melanogaster/metabolismo , Drosophila melanogaster/genética , Enfermedad de Machado-Joseph/metabolismo , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/patología , Enterocitos/metabolismo , Modelos Animales de Enfermedad , Ataxina-3/metabolismo , Ataxina-3/genética , Drosophila/metabolismoRESUMEN
Spinocerebellar ataxia type 3 (SCA3) is primarily characterized by progressive cerebellar degeneration, including gray matter atrophy and disrupted anatomical and functional connectivity. The alterations of cerebellar white matter structural network in SCA3 and the underlying neurobiological mechanism remain unknown. Using a cohort of 20 patients with SCA3 and 20 healthy controls, we constructed cerebellar structural networks from diffusion MRI and investigated alterations of topological organization. Then, we mapped the alterations with transcriptome data from the Allen Human Brain Atlas to identify possible biological mechanisms for regional selective vulnerability to white matter damage. Compared with healthy controls, SCA3 patients exhibited reduced global and nodal efficiency, along with a widespread decrease in edge strength, particularly affecting edges connected to hub regions. The strength of inter-module connections was lower in SCA3 group and negatively correlated with the Scale for the Assessment and Rating of Ataxia score, International Cooperative Ataxia Rating Scale score, and cytosine-adenine-guanine repeat number. Moreover, the transcriptome-connectome association study identified the expression of genes involved in synapse-related and metabolic biological processes. These findings suggest a mechanism of white matter vulnerability and a potential image biomarker for the disease severity, providing insights into neurodegeneration and pathogenesis in this disease.
Asunto(s)
Cerebelo , Conectoma , Enfermedad de Machado-Joseph , Transcriptoma , Humanos , Masculino , Femenino , Cerebelo/diagnóstico por imagen , Cerebelo/patología , Persona de Mediana Edad , Adulto , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/diagnóstico por imagen , Enfermedad de Machado-Joseph/patología , Sustancia Blanca/diagnóstico por imagen , Sustancia Blanca/patología , Imagen de Difusión por Resonancia MagnéticaRESUMEN
Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease, is reported to be the most common type of autosomal dominant cerebellar ataxia (ADCA). SCA3 patients suffer from a progressive decline in motor coordination and other disease-associated symptoms. Moreover, recent studies have reported that SCA3 patients also exhibit symptoms of cerebellar cognitive affective syndrome (CCAS). We previously observed signs of CCAS in mouse model of SCA3. Particularly, SCA3-84Q mice suffer from anxiety, recognition memory decline, and also exhibit signs of low mood and aversion to activity. Here we studied the effect of long-term injections of SK channels activator chlorzoxazone (CHZ) together and separately with the folic acid (FA) on the cerebellar Purkinje cell (PC) firing and histology, and also on the motor and cognitive functions as well as mood alterations in SCA3-84Q hemizygous transgenic mice. We realized that both CHZ and CHZ-FA combination had similar positive effect on pure cerebellum impairments including PC firing precision, PC histology, and motor performance in SCA3-84Q mice. However, only the CHZ-FA combination, but not CHZ, had significantly ameliorated the signs of anxiety and depression, and also noticeably improved recognition memory in SCA3-84Q mice. Our results suggest that the combination therapy for both ataxia and non-motor symptoms is required for the complex treatment of ADCA.
Asunto(s)
Ansiedad , Clorzoxazona , Depresión , Modelos Animales de Enfermedad , Ácido Fólico , Enfermedad de Machado-Joseph , Ratones Transgénicos , Animales , Ratones , Ansiedad/tratamiento farmacológico , Ansiedad/fisiopatología , Depresión/tratamiento farmacológico , Depresión/genética , Depresión/fisiopatología , Ácido Fólico/farmacología , Ácido Fólico/administración & dosificación , Enfermedad de Machado-Joseph/tratamiento farmacológico , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/fisiopatología , Enfermedad de Machado-Joseph/patología , Clorzoxazona/farmacología , Células de Purkinje/efectos de los fármacos , Células de Purkinje/metabolismo , Células de Purkinje/patología , Memoria/efectos de los fármacos , Humanos , Cerebelo/efectos de los fármacos , Cerebelo/metabolismo , Masculino , Ataxina-3/genética , Ataxina-3/metabolismoRESUMEN
Spinocerebellar ataxia type 3 (SCA3) is the most common dominantly inherited ataxia. Currently, no preventive or disease-modifying treatments exist for this progressive neurodegenerative disorder, although efforts using gene silencing approaches are under clinical trial investigation. The disease is caused by a CAG repeat expansion in the mutant gene, ATXN3, producing an enlarged polyglutamine tract in the mutant protein. Similar to other paradigmatic neurodegenerative diseases, studies evaluating the pathogenic mechanism focus primarily on neuronal implications. Consequently, therapeutic interventions often overlook non-neuronal contributions to disease. Our lab recently reported that oligodendrocytes display some of the earliest and most progressive dysfunction in SCA3 mice. Evidence of disease-associated oligodendrocyte signatures has also been reported in other neurodegenerative diseases, including Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and Huntington's disease. Here, we assess the effects of anti-ATXN3 antisense oligonucleotide (ASO) treatment on oligodendrocyte dysfunction in premanifest and symptomatic SCA3 mice. We report a severe, but modifiable, deficit in oligodendrocyte maturation caused by the toxic gain-of-function of mutant ATXN3 early in SCA3 disease that is transcriptionally, biochemically, and functionally rescued with anti-ATXN3 ASO. Our results highlight the promising use of an ASO therapy across neurodegenerative diseases that requires glial targeting in addition to affected neuronal populations.
Asunto(s)
Ataxina-3 , Modelos Animales de Enfermedad , Enfermedad de Machado-Joseph , Oligodendroglía , Oligonucleótidos Antisentido , Animales , Oligodendroglía/metabolismo , Ratones , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/terapia , Enfermedad de Machado-Joseph/patología , Enfermedad de Machado-Joseph/metabolismo , Ataxina-3/genética , Ataxina-3/metabolismo , Humanos , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Ratones TransgénicosRESUMEN
Machado-Joseph disease (MJD) is a devastating and incurable neurodegenerative disease characterised by progressive ataxia, difficulty speaking and swallowing. Consequently, affected individuals ultimately become wheelchair dependent, require constant care, and face a shortened life expectancy. The monogenic cause of MJD is expansion of a trinucleotide (CAG) repeat region within the ATXN3 gene, which results in polyglutamine (polyQ) expansion within the resultant ataxin-3 protein. While it is well established that the ataxin-3 protein functions as a deubiquitinating (DUB) enzyme and is therefore critically involved in proteostasis, several unanswered questions remain regarding the impact of polyQ expansion in ataxin-3 on its DUB function. Here we review the current literature surrounding ataxin-3's DUB function, its DUB targets, and what is known regarding the impact of polyQ expansion on ataxin-3's DUB function. We also consider the potential neuroprotective effects of ataxin-3's DUB function, and the intersection of ataxin-3's role as a DUB enzyme and regulator of gene transcription. Ataxin-3 is the principal pathogenic protein in MJD and also appears to be involved in cancer. As aberrant deubiquitination has been linked to both neurodegeneration and cancer, a comprehensive understanding of ataxin-3's DUB function is important for elucidating potential therapeutic targets in these complex conditions. In this review, we aim to consolidate knowledge of ataxin-3 as a DUB and unveil areas for future research to aid therapeutic targeting of ataxin-3's DUB function for the treatment of MJD and other diseases.
Asunto(s)
Enfermedad de Machado-Joseph , Neoplasias , Enfermedades Neurodegenerativas , Humanos , Ataxina-3/genética , Ataxina-3/metabolismo , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/metabolismo , Enfermedad de Machado-Joseph/patología , Enfermedades Neurodegenerativas/genéticaRESUMEN
Spinocerebellar ataxia 3 (SCA3) is an incurable, neurodegenerative genetic disorder that leads to progressive cerebellar ataxia and other parkinsonian-like pathologies because of loss of cerebellar neurons. The role of an expanded polyglutamine aggregate on neural progenitor cells is unknown. Here, we show that SCA3 patient-specific induced neural progenitor cells (iNPCs) exhibit proliferative defects. Moreover, SCA3 iNPCs have reduced autophagic expression compared to control. Furthermore, although SCA3 iNPCs continue to proliferate, they do not survive subsequent passages compared to control iNPCs, indicating the likelihood that SCA3 iNPCs undergo rapid senescence. Exposure to interleukin-4 (IL-4), a type 2 cytokine produced by immune cells, resulted in an observed increase in expression of autophagic programs and a reduction in the proliferation defect observed in SCA3 iNPCs. Our results indicate a previously unobserved role of SCA3 disease ontology on the neural stem cell pool and a potential therapeutic strategy using IL-4 to ameliorate or delay disease pathology in the SCA3 neural progenitor cell population.
Asunto(s)
Enfermedad de Machado-Joseph , Células-Madre Neurales , Humanos , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/metabolismo , Enfermedad de Machado-Joseph/patología , Interleucina-4 , Citocinas/metabolismo , Factor de Transcripción STAT6/metabolismoRESUMEN
BACKGROUND: Spinocerebellar ataxia type 3 (SCA3) is an inherited, autosomal, and rare neurodegenerative disease. Serum/plasma biomarkers or functional magnetic resonance imaging used to assess progression, except for neurological examinations, is either inconvenient or expensive. Handgrip strength (HGS) may be considered as a biomarker to predict the progress of SCA3 and align with the alteration of plasma neurofilament light chain (NfL) and Scale for the Assessment and Rating of Ataxia (SARA). METHODS: Patients with SCA3 and healthy subjects were recruited from Changhua Christian Hospital. SARA, body mass index (BMI), and NfL were obtained for both groups. HGS was measured using a Jamar Plus + hand dynamometer. RESULTS: This study recruited 31 patients and 36 controls. HGS in the SCA3 group revealed a profound decrease (P < 0.001) compared with normal subjects. HGS also had a negative correlation with SARA (r = - 0.548, P = 0.001), NfL (r = - 0.359, P = 0.048), and a positive correlation with BMI (r = 0.680, P < 0.001). Moreover, HGS/BMI ratio correlated with SARA (r = - 0.441, P = 0.013). Controlling for gender and age, HGS still correlated with the above clinical items. The initial hypothesis was also proved in SCA3 84Q transgenic mice, showing grip strength weakness compared to normal mice. CONCLUSIONS: HGS can be an alternative tool to assess the clinical severity of SCA3. Further research is needed to investigate the underlying mechanisms.
Asunto(s)
Enfermedad de Machado-Joseph , Ataxias Espinocerebelosas , Humanos , Ratones , Animales , Enfermedad de Machado-Joseph/patología , Proyectos Piloto , Fuerza de la Mano , Progresión de la EnfermedadRESUMEN
The accumulation of mutant ataxin-3 (Atx3) in neuronal nuclear inclusions is a pathological hallmark of Machado-Joseph disease (MJD), also known as Spinocerebellar Ataxia Type 3. Decreasing the protein aggregation burden is a possible disease-modifying strategy to tackle MJD and other neurodegenerative disorders for which only symptomatic treatments are currently available. We performed a drug repurposing screening to identify inhibitors of Atx3 aggregation with known toxicological and pharmacokinetic profiles. Interestingly, dopamine hydrochloride and other catecholamines are among the most potent inhibitors of Atx3 aggregation in vitro. Our results indicate that low micromolar concentrations of dopamine markedly delay the formation of mature amyloid fibrils of mutant Atx3 through the inhibition of the earlier oligomerization steps. Although dopamine itself does not cross the blood-brain barrier, dopamine levels in the brain can be increased by low doses of dopamine precursors and dopamine agonists commonly used to treat Parkinsonian symptoms. In agreement, treatment with levodopa ameliorated motor symptoms in a C. elegans model of MJD. These findings suggest a possible application of dopaminergic drugs to halt or reduce Atx3 accumulation in the brains of MJD patients.
Asunto(s)
Enfermedad de Machado-Joseph , Proteínas Nucleares , Animales , Humanos , Ataxina-3/genética , Proteínas Nucleares/metabolismo , Proteínas Represoras/metabolismo , Dopamina , Reposicionamiento de Medicamentos , Caenorhabditis elegans/metabolismo , Enfermedad de Machado-Joseph/tratamiento farmacológico , Enfermedad de Machado-Joseph/metabolismo , Enfermedad de Machado-Joseph/patología , DopaminérgicosRESUMEN
BACKGROUND: Accumulating evidences indicate regional gray matter (GM) morphology atrophy in spinocerebellar ataxia type 3 (SCA3); however, whether large-scale morphological brain networks (MBNs) undergo widespread reorganization in these patients remains unclear. OBJECTIVE: To investigate the topological organization of large-scale individual-based MBNs in SCA3 patients. METHODS: The individual-based MBNs were constructed based on the inter-regional morphological similarity of GM regions. Graph theoretical analysis was taken to assess GM structural connectivity in 76 symptomatic SCA3, 24 pre-symptomatic SCA3, and 54 healthy normal controls (NCs). Topological parameters of the resulting graphs and network-based statistics analysis were compared among symptomatic SCA3, pre-symptomatic SCA3, and NCs groups. The inner association between network properties and clinical variables was further analyzed. RESULTS: Compared to NCs and pre-symptomatic SCA3 patients, symptomatic SCA3 indicated significantly decreased integration and segregation, a shift to "weaker small-worldness", characterized by decreased Cp , lower Eloc, and Eglob (all p < 0.005). Regarding nodal properties, symptomatic SCA3 exhibited significantly decreased nodal profiles in the central executive network (CEN)-related left inferior frontal gyrus, limbic regions involving the bilateral amygdala, left hippocampus, and bilateral pallidum, thalamus; and increased nodal degree, efficiency in bilateral caudate (all pFDR <0.05). Meanwhile, clinical variables were correlated with altered nodal profiles (pFDR ≤0.029). SCA3-related subnetwork was closely interrelated with dorsolateral cortico-striatal circuitry extending to orbitofrontal-striatal circuits and dorsal visual systems (lingual gyrus-striatal). CONCLUSION: Symptomatic SCA3 patients undergo an extensive and significant reorganization in large-scale individual-based MBNs, probably due to disrupted prefrontal cortico-striato-thalamo-cortical loops, limbic-striatum circuitry, and enhanced connectivity in the neostriatum. This study highlights the crucial role of abnormal morphological connectivity alterations beyond the pattern of brain atrophy, which might pave the way for therapeutic development in the future.
Asunto(s)
Enfermedad de Machado-Joseph , Humanos , Enfermedad de Machado-Joseph/diagnóstico por imagen , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/patología , Imagen por Resonancia Magnética/métodos , Encéfalo/diagnóstico por imagen , Encéfalo/patología , Sustancia Gris/diagnóstico por imagen , Sustancia Gris/patología , Atrofia/patologíaRESUMEN
Machado-Joseph disease (MJD) is a dominant neurodegenerative disease caused by an expanded CAG repeat in the ATXN3 gene encoding the ataxin-3 protein. Several cellular processes, including transcription and apoptosis, are disrupted in MJD. To gain further insights into the extent of dysregulation of mitochondrial apoptosis in MJD and to evaluate if expression alterations of specific apoptosis genes/proteins can be used as transcriptional biomarkers of disease, the expression levels of BCL2, BAX and TP53 and the BCL2/BAX ratio (an indicator of susceptibility to apoptosis) were assessed in blood and post-mortem brain samples from MJD subjects and MJD transgenic mice and controls. While patients show reduced levels of blood BCL2 transcripts, this measurement displays low accuracy to discriminate patients from matched controls. However, increased levels of blood BAX transcripts and decreased BCL2/BAX ratio are associated with earlier onset of disease, indicating a possible association with MJD pathogenesis. Post-mortem MJD brains show increased BCL2/BAX transcript ratio in the dentate cerebellar nucleus (DCN) and increased BCL2/BAX insoluble protein ratio in the DCN and pons, suggesting that in these regions, severely affected by degeneration in MJD, cells show signs of apoptosis resistance. Interestingly, a follow-up study of 18 patients further shows that blood BCL2 and TP53 transcript levels increase over time in MJD patients. Furthermore, while the similar levels of blood BCL2, BAX, and TP53 transcripts observed in preclinical subjects and controls is mimicked by pre-symptomatic MJD mice, the expression profile of these genes in patient brains is partially replicated by symptomatic MJD mice. Globally, our findings indicate that there is tissue-specific vulnerability to apoptosis in MJD subjects and that this tissue-dependent behavior is partially replicated in a MJD mouse model.
Asunto(s)
Enfermedad de Machado-Joseph , Enfermedades Neurodegenerativas , Ratones , Animales , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/metabolismo , Enfermedad de Machado-Joseph/patología , Estudios de Seguimiento , Enfermedades Neurodegenerativas/complicaciones , Proteína X Asociada a bcl-2/genética , Ratones Transgénicos , ApoptosisRESUMEN
OBJECTIVE: Spinocerebellar ataxia type 3 (SCA3) is the most common dominantly inherited ataxia, and biomarkers are needed to noninvasively monitor disease progression and treatment response. Anti-ATXN3 antisense oligonucleotide (ASO) treatment has been shown to mitigate neuropathology and rescue motor phenotypes in SCA3 mice. Here, we investigated whether repeated ASO administration reverses brainstem and cerebellar neurochemical abnormalities by magnetic resonance spectroscopy (MRS). METHODS: Symptomatic SCA3 mice received intracerebroventricular treatment of ASO or vehicle and were compared to wild-type vehicle-treated littermates. To quantify neurochemical changes in treated mice, longitudinal 9.4T MRS of cerebellum and brainstem was performed. Acquired magnetic resonance (MR) group means were analyzed by 2-way analysis of variance mixed-effects sex-adjusted analysis with post hoc Sidak correlation for multiple comparisons. Pearson correlations were used to relate SCA3 pathology and behavior. RESULTS: MR spectra yielded 15 to 16 neurochemical concentrations in the cerebellum and brainstem. ASO treatment in SCA3 mice resulted in significant total choline rescue and partial reversals of taurine, glutamine, and total N-acetylaspartate across both regions. Some ASO-rescued neurochemicals correlated with reduction in diseased protein and nuclear ATXN3 accumulation. ASO-corrected motor activity correlated with total choline and total N-acetylaspartate levels early in disease. INTERPRETATION: SCA3 mouse cerebellar and brainstem neurochemical trends parallel those in patients with SCA3. Decreased total choline may reflect oligodendrocyte abnormalities, decreased total N-acetylaspartate highlights neuronal health disturbances, and high glutamine may indicate gliosis. ASO treatment fully or partially reversed select neurochemical abnormalities in SCA3 mice, indicating the potential for these measures to serve as noninvasive treatment biomarkers in future SCA3 gene silencing trials. ANN NEUROL 2023;94:658-671.
Asunto(s)
Enfermedad de Machado-Joseph , Neuroquímica , Humanos , Ratones , Animales , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/patología , Oligonucleótidos Antisentido/uso terapéutico , Glutamina , Biomarcadores , Colina/metabolismoRESUMEN
Emerging evidence suggests the presence of bidirectional interactions between the central nervous system and gut microbiota that may contribute to the pathogenesis of neurodegenerative diseases. However, the potential role of gut microbes in forms of spinocerebellar ataxia, such as the fatal neurodegenerative disease Machado Joseph disease (MJD), remains unexplored. Here, we examined whether gut microbiota alterations may be an early disease phenotype of MJD. We profiled the gut microbiota of male and female transgenic MJD mice (CMVMJD135) expressing human ATXN3 with expanded CAG repeats (133-143 CAG) at pre-symptomatic, symptomatic and well-established stages of the disease (7, 11 and 15 weeks of age, respectively). We compared these profiles with the gut microbiota of male and female wild-type (WT) littermate control mice at same ages. Correlation network analyses were employed to explore the relevance of microbiota changes to disease progression. The results demontrated distinct sex-dependent effects in disease development whereby male MJD mice displayed earlier motor impairments than female MJD mice. The gut microbiota community structure and composition also demonstrated sex-specific differences between MJD and WT mice. In both male and female MJD mice, the shifts in the microbiota were present by 7 weeks, before the onset of any symptoms. These pre-symptomatic microbial changes correlated with the severity of neurological impairments present at later stages of the disease. Previous efforts towards developing treatments for MJD have failed to yield meaningful outcomes. Our study reports a novel relationship between the gut microbiota and MJD development and severity. Elucidating how gut microbes are involved in MJD pathogenesis may offer new and efficacious treatment strategies for this currently untreatable disease.
Asunto(s)
Microbioma Gastrointestinal , Enfermedad de Machado-Joseph , Ataxias Espinocerebelosas , Masculino , Humanos , Femenino , Ratones , Animales , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/patología , Ratones Transgénicos , Fenotipo , Ataxina-3/genéticaRESUMEN
OBJECTIVES: To investigate and characterize the structural alterations of the brain in SCA3, and their correlations with the scale for the assessment and rating of ataxia (SARA) and normal brain ATXN3 expression. METHODS: We performed multimodal analyses in 52 SCA3 (15 pre-symptomatic) and healthy controls (HCs) (n = 35) to assess the abnormalities of gray and white matter (WM) of the cerebrum, brainstem, and cerebellum via FreeSurfer, SUIT, and TBSS, and their associations with disease severity. Twenty SCA3 patients (5 pre- and 15 symptomatic) were followed for at least a year. Besides, we uncovered the normal pattern of brain ATXN3 spatial distribution. RESULTS: Pre-symptomatic patients showed only WM damage, mainly in the cerebellar peduncles, compared to HCs. In the advanced stage, the WM damage followed a caudal-rostral pattern. Meanwhile, continuous nonlinear structure damage was characterized by brainstem volumetric reduction and relatively symmetric cerebellar and basal ganglia atrophy but spared the cerebral cortex, partially explained by the ATXN3 overexpression. The bilateral pallidum, brainstem, and cerebellar peduncles demonstrated a very large effect size. Besides, all these alterations were significantly correlated with SARA; the pons (r = -0.65) and superior cerebellar peduncle (r = -0.68) volume demonstrated a higher correlation than the cerebellum with SARA. The longitudinal study further uncovered progressive atrophy of pons in symptomatic SCA3. CONCLUSIONS: Significant WM damage starts before the ataxia onset. The bilateral pallidum, brainstem, and cerebellar peduncles are the most vulnerable targets. The volume of pons appears to be the most promising imaging biomarker for a longitudinal study. TRIAL REGISTRATION: ClinicalTrial ID: ChiCTR2100045857 ( http://www.chictr.org.cn/edit.aspx?pid=55652&htm=4 ) KEY POINTS: ⢠Pre- SCA3 showed WM damage mainly in cerebellar peduncles. Continuous brain damage was characterized by brainstem, widespread, and relatively symmetric cerebellar and basal ganglia atrophy. ⢠Volumetric abnormalities were most evident in the bilateral pallidum, brainstem, and cerebellar peduncles in SCA3. ⢠The volume of pons might identify the disease progression longitudinally.
Asunto(s)
Enfermedad de Machado-Joseph , Imagen por Resonancia Magnética , Humanos , Atrofia/diagnóstico por imagen , Atrofia/patología , Encéfalo/diagnóstico por imagen , Encéfalo/patología , Cerebelo/diagnóstico por imagen , Cerebelo/patología , Estudios Longitudinales , Enfermedad de Machado-Joseph/diagnóstico por imagen , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/patología , Imagen por Resonancia Magnética/métodosRESUMEN
Coenzyme Q10 (CoQ10), a well-known antioxidant, has been explored as a treatment in several neurodegenerative diseases, but its utility in spinocerebellar ataxia type 3 (SCA3) has not been explored. Herein, the protective effect of CoQ10 was examined using a transgenic mouse model of SCA3 onset. These results demonstrated that a diet supplemented with CoQ10 significantly improved murine locomotion, revealed by rotarod and open-field tests, compared with untreated controls. Additionally, a histological analysis showed the stratification of cerebellar layers indistinguishable from that of wild-type littermates. The increased survival of Purkinje cells was reflected by the reduced abundance of TUNEL-positive nuclei and apoptosis markers of activated p53, as well as lower levels of cleaved caspase 3 and cleaved poly-ADP-ribose polymerase. CoQ10 effects were related to the facilitation of the autophagy-mediated clearance of mutant ataxin-3 protein, as evidenced by the increased expression of heat shock protein 27 and autophagic markers p62, Beclin-1 and LC3II. The expression of antioxidant enzymes heme oxygenase 1 (HO-1), glutathione peroxidase 1 (GPx1) and superoxide dismutase 1 (SOD1) and 2 (SOD2), but not of glutathione peroxidase 2 (GPx2), were restored in 84Q SCA3 mice treated with CoQ10 to levels even higher than those measured in wild-type control mice. Furthermore, CoQ10 treatment also prevented skeletal muscle weight loss and muscle atrophy in diseased mice, revealed by significantly increased muscle fiber area and upregulated muscle protein synthesis pathways. In summary, our results demonstrated biochemical and pharmacological bases for the possible use of CoQ10 in SCA3 therapy.
Asunto(s)
Enfermedad de Machado-Joseph , Animales , Antioxidantes/uso terapéutico , Suplementos Dietéticos , Enfermedad de Machado-Joseph/tratamiento farmacológico , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/patología , Ratones , Ratones Transgénicos , Péptidos , Ubiquinona/análogos & derivadosRESUMEN
Emerging evidence has implicated non-neuronal cells, particularly oligodendrocytes, in the pathophysiology of many neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease and Spinocerebellar ataxia type 3 (SCA3). We recently demonstrated that cell-autonomous dysfunction of oligodendrocyte maturation is one of the of the earliest and most robust changes in vulnerable regions of the SCA3 mouse brain. However, the cell- and disease-specific mechanisms that underlie oligodendrocyte dysfunction remain poorly understood and are difficult to isolate in vivo. In this study, we used primary oligodendrocyte cultures to determine how known pathogenic SCA3 mechanisms affect this cell type. We isolated oligodendrocyte progenitor cells from 5- to 7-day-old mice that overexpress human mutant ATXN3 or lack mouse ATXN3 and differentiated them for up to 5 days in vitro. Utilizing immunocytochemistry, we characterized the contributions of ATXN3 toxic gain-of-function and loss-of-function in oligodendrocyte maturation, protein quality pathways, DNA damage signaling, and methylation status. We illustrate the utility of primary oligodendrocyte culture for elucidating cell-specific pathway dysregulation relevant to SCA3. Given recent work demonstrating disease-associated oligodendrocyte signatures in other neurodegenerative diseases, this novel model has broad applicability in revealing mechanistic insights of oligodendrocyte contribution to pathogenesis.
Asunto(s)
Enfermedad de Machado-Joseph , Enfermedades Neurodegenerativas , Animales , Ataxina-3/genética , Ataxina-3/metabolismo , Modelos Animales de Enfermedad , Humanos , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/metabolismo , Enfermedad de Machado-Joseph/patología , Ratones , Oligodendroglía/metabolismoRESUMEN
The most common autosomal dominant ataxia worldwide, spinocerebellar ataxia type 3 (SCA3) is a fatal, progressive neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the ATXN3 gene. Here we report the generation of human embryonic stem cell (hESC) line UM134-1, the first SCA3 disease-specific hESC line to be added to the NIH hESC registry. UM134-1 pluripotency was confirmed by immunocytochemistry and PCR for pluripotency markers and by the ability to form three germ layers in vitro. The established hESC line provides a useful new human cell model to study the pathogenesis of SCA3.