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1.
JCI Insight ; 6(3)2021 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-33554954

RESUMO

Spinocerebellar ataxia type 1 (SCA1) is an adult-onset neurodegenerative disorder characterized by motor incoordination, mild cognitive decline, respiratory dysfunction, and early lethality. It is caused by the expansion of the polyglutamine (polyQ) tract in Ataxin-1 (ATXN1), which stabilizes the protein, leading to its toxic accumulation in neurons. Previously, we showed that serine 776 (S776) phosphorylation is critical for ATXN1 stability and contributes to its toxicity in cerebellar Purkinje cells. Still, the therapeutic potential of disrupting S776 phosphorylation on noncerebellar SCA1 phenotypes remains unstudied. Here, we report that abolishing S776 phosphorylation specifically on the polyQ-expanded ATXN1 of SCA1-knockin mice reduces ATXN1 throughout the brain and not only rescues the cerebellar motor incoordination but also improves respiratory function and extends survival while not affecting the hippocampal learning and memory deficits. As therapeutic approaches are likely to decrease S776 phosphorylation on polyQ-expanded and WT ATXN1, we further disrupted S776 phosphorylation on both alleles and observed an attenuated rescue, demonstrating a potential protective role of WT allele. This study not only highlights the role of S776 phosphorylation to regulate ATXN1 levels throughout the brain but also suggests distinct brain region-specific disease mechanisms and demonstrates the importance of developing allele-specific therapies for maximal benefits in SCA1.

2.
Hum Mol Genet ; 29(19): 3249-3265, 2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-32964235

RESUMO

Selective neuronal vulnerability in neurodegenerative disease is poorly understood. Using the ATXN1[82Q] model of spinocerebellar ataxia type 1 (SCA1), we explored the hypothesis that regional differences in Purkinje neuron degeneration could provide novel insights into selective vulnerability. ATXN1[82Q] Purkinje neurons from the anterior cerebellum were found to degenerate earlier than those from the nodular zone, and this early degeneration was associated with selective dysregulation of ion channel transcripts and altered Purkinje neuron spiking. Efforts to understand the basis for selective dysregulation of channel transcripts revealed modestly increased expression of the ATXN1 co-repressor Capicua (Cic) in anterior cerebellar Purkinje neurons. Importantly, disrupting the association between ATXN1 and Cic rescued the levels of these ion channel transcripts, and lentiviral overexpression of Cic in the nodular zone accelerated both aberrant Purkinje neuron spiking and neurodegeneration. These findings reinforce the central role for Cic in SCA1 cerebellar pathophysiology and suggest that only modest reductions in Cic are needed to have profound therapeutic impact in SCA1.

3.
Mol Ther Nucleic Acids ; 21: 1006-1016, 2020 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-32818920

RESUMO

Spinocerebellar ataxia type 1 (SCA1) is a lethal, autosomal dominant neurodegenerative disease caused by a polyglutamine expansion in the ATAXIN-1 (ATXN1) protein. Preclinical studies demonstrate the therapeutic efficacy of approaches that target and reduce Atxn1 expression in a non-allele-specific manner. However, studies using Atxn1-/- mice raise cautionary notes that therapeutic reductions of ATXN1 might lead to undesirable effects such as reduction in the activity of the tumor suppressor Capicua (CIC), activation of the protease ß-secretase 1 (BACE1) and subsequent increased amyloidogenic cleavage of the amyloid precursor protein (APP), or a reduction in hippocampal neuronal precursor cells that would impact hippocampal function. Here, we tested whether an antisense oligonucleotide (ASO)-mediated reduction of Atxn1 produced unwanted effects involving BACE1, CIC activity, or reduction in hippocampal neuronal precursor cells. Notably, no effects on BACE1, CIC tumor suppressor function, or number of hippocampal neuronal precursor cells were found in mice subjected to a chronic in vivo ASO-mediated reduction of Atxn1. These data provide further support for targeted reductions of ATXN1 as a therapeutic approach for SCA1.

4.
Nat Commun ; 11(1): 3343, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620905

RESUMO

The expanded polyglutamine (polyQ) tract form of ataxin-1 drives disease progression in spinocerebellar ataxia type 1 (SCA1). Although known to form distinctive intranuclear bodies, the cellular pathways and processes that polyQ-ataxin-1 influences remain poorly understood. Here we identify the direct and proximal partners constituting the interactome of ataxin-1[85Q] in Neuro-2a cells, pathways analyses indicating a significant enrichment of essential nuclear transporters, pointing to disruptions in nuclear transport processes in the presence of elevated levels of ataxin-1. Our direct assessments of nuclear transporters and their cargoes confirm these observations, revealing disrupted trafficking often with relocalisation of transporters and/or cargoes to ataxin-1[85Q] nuclear bodies. Analogous changes in importin-ß1, nucleoporin 98 and nucleoporin 62 nuclear rim staining are observed in Purkinje cells of ATXN1[82Q] mice. The results highlight a disruption of multiple essential nuclear protein trafficking pathways by polyQ-ataxin-1, a key contribution to furthering understanding of pathogenic mechanisms initiated by polyQ tract proteins.


Assuntos
Ataxina-1/metabolismo , Núcleo Celular/metabolismo , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Células de Purkinje/metabolismo , Transporte Ativo do Núcleo Celular/genética , Animais , Ataxina-1/genética , Linhagem Celular Tumoral , Modelos Animais de Doenças , Células HeLa , Humanos , Camundongos , Mutação , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Proteínas de Transporte Nucleocitoplasmático/genética , Peptídeos/genética , Ligação Proteica , Ataxias Espinocerebelares/genética , Ataxias Espinocerebelares/metabolismo , Expansão das Repetições de Trinucleotídeos/genética
5.
Neuropsychopharmacology ; 45(7): 1159-1170, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32179875

RESUMO

Autism spectrum disorder (ASD) encompasses wide-ranging neuropsychiatric symptoms with unclear etiology. Although the cerebellum is a key region implicated in ASD, it remains elusive how the cerebellar circuitry is altered and whether the cerebellum can serve as a therapeutic target to rectify the phenotype of idiopathic ASD with polygenic abnormalities. Using a syndromic ASD model, e.g., Black and Tan BRachyury T+Itpr3tf/J (BTBR) mice, we revealed that increased excitability of presynaptic interneurons (INs) and decreased intrinsic excitability of postsynaptic Purkinje neurons (PNs) resulted in low PN firing rates in the cerebellum. Knowing that downregulation of Kv1.2 potassium channel in the IN nerve terminals likely augmented their excitability and GABA release, we applied a positive Kv1.2 modulator to mitigate the presynaptic over-inhibition and social impairment of BTBR mice. Selective restoration of the PN activity by a new chemogenetic approach alleviated core ASD-like behaviors of the BTBR strain. These findings highlight complex mechanisms converging onto the cerebellar dysfunction in the phenotypic model and provide effective strategies for potential therapies of ASD.

6.
Kaohsiung J Med Sci ; 35(11): 679-685, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31271500

RESUMO

Spinocerebellar ataxia (SCA) type 1 (SCA1) is a rare autosomal dominant disorder that is characterized by worsening of disordered coordination, ataxia of the trunk, and other neurological symptoms. Physical activity improves both mobility and the daily living activities of patients with SCA. Intervention with daily regular treadmill exercise may slow the deterioration of cerebellar neurons in SCA1. Therefore, the signal changes and performance of cerebellar neurons after exercise in SCA1 was investigated in this study. We employed a transgenic mouse model of SCA1, generated by amplifying the cytosine-adenine-guanine trinucleotide repeat expansions, and the mice underwent 1 month of moderate daily treadmill exercise for 1 hour. The rotarod test revealed that the motor function of the SCA1 mice that underwent training was superior to that of the control SCA1 mice, which did not undergo training. Moreover, the cerebellar pathology revealed preserved Purkinje neurons stained by carbindin with an increase of the neuronal Per Arnt Sim domain protein 4, a key regulation in the structural and functional plasticity of neurons, in the excised SCA1 mice relative to the controls. The mechanism was related to an increase of phosphorylation of ribosomal protein S6, a downstream target of the mammalian target of rapamycin pathway, but not to autophagy activation. This study determined that regular treadmill exercise may play a crucial role in the viable support of cerebellar neurons in SCA1.


Assuntos
Cerebelo/patologia , Atividade Motora , Neurônios/patologia , Condicionamento Físico Animal , Ataxias Espinocerebelares/patologia , Ataxias Espinocerebelares/fisiopatologia , Animais , Autofagia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Contagem de Células , Sobrevivência Celular , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Plasticidade Neuronal , Neurônios/metabolismo , Fosforilação , Células de Purkinje/patologia , Proteína S6 Ribossômica/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo
7.
JCI Insight ; 3(21)2018 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-30385727

RESUMO

Spinocerebellar ataxia type 1 (SCA1) is a dominantly inherited ataxia caused by expansion of a translated CAG repeat encoding a glutamine tract in the ataxin-1 (ATXN1) protein. Despite advances in understanding the pathogenesis of SCA1, there are still no therapies to alter its progressive fatal course. RNA-targeting approaches have improved disease symptoms in preclinical rodent models of several neurological diseases. Here, we investigated the therapeutic capability of an antisense oligonucleotide (ASO) targeting mouse Atxn1 in Atxn1154Q/2Q-knockin mice that manifest motor deficits and premature lethality. Following a single ASO treatment at 5 weeks of age, mice demonstrated rescue of these disease-associated phenotypes. RNA-sequencing analysis of genes with expression restored to WT levels in ASO-treated Atxn1154Q/2Q mice was used to demonstrate molecular differences between SCA1 pathogenesis in the cerebellum and disease in the medulla. Finally, select neurochemical abnormalities detected by magnetic resonance spectroscopy in vehicle-treated Atxn1154Q/2Q mice were reversed in the cerebellum and brainstem (a region containing the pons and the medulla) of ASO-treated Atxn1154Q/2Q mice. Together, these findings support the efficacy and therapeutic importance of directly targeting ATXN1 RNA expression as a strategy for treating both motor deficits and lethality in SCA1.


Assuntos
Ataxina-1/efeitos dos fármacos , Doenças Neurodegenerativas/genética , Oligonucleotídeos Antissenso/uso terapêutico , Ataxias Espinocerebelares/classificação , Animais , Ataxina-1/metabolismo , Feminino , Espectroscopia de Ressonância Magnética/métodos , Masculino , Camundongos , Proteínas do Tecido Nervoso/efeitos dos fármacos , Proteínas do Tecido Nervoso/metabolismo , Doenças Neurodegenerativas/tratamento farmacológico , Oligonucleotídeos Antissenso/administração & dosagem , Oligonucleotídeos Antissenso/efeitos adversos , Fenótipo , Análise de Sequência de RNA/métodos , Ataxias Espinocerebelares/diagnóstico por imagem , Ataxias Espinocerebelares/tratamento farmacológico , Ataxias Espinocerebelares/genética , Análise de Sobrevida , Transcriptoma
8.
Hum Mol Genet ; 27(16): 2863-2873, 2018 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-29860311

RESUMO

Spinocerebellar ataxia type 1 (SCA1) is caused by the expansion of a trinucleotide repeat that encodes a polyglutamine tract in ataxin-1 (ATXN1). The expanded polyglutamine in ATXN1 increases the protein's stability and results in its accumulation and toxicity. Previous studies have demonstrated that decreasing ATXN1 levels ameliorates SCA1 phenotypes and pathology in mouse models. We rationalized that reducing ATXN1 levels through pharmacological inhibition of its modulators could provide a therapeutic avenue for SCA1. Here, through a forward genetic screen in Drosophila we identified, p21-activated kinase 3 (Pak3) as a modulator of ATXN1 levels. Loss-of-function of fly Pak3 or Pak1, whose mammalian homologs belong to Group I of PAK proteins, reduces ATXN1 levels, and accordingly, improves disease pathology in a Drosophila model of SCA1. Knockdown of PAK1 potently reduces ATXN1 levels in mammalian cells independent of the well-characterized S776 phosphorylation site (known to stabilize ATXN1) thus revealing a novel molecular pathway that regulates ATXN1 levels. Furthermore, pharmacological inhibition of PAKs decreases ATXN1 levels in a mouse model of SCA1. To explore the potential of using PAK inhibitors in combination therapy, we combined the pharmacological inhibition of PAK with MSK1, a previously identified modulator of ATXN1, and examined their effects on ATXN1 levels. We found that inhibition of both pathways results in an additive decrease in ATXN1 levels. Together, this study identifies PAK signaling as a distinct molecular pathway that regulates ATXN1 levels and presents a promising opportunity to pursue for developing potential therapeutics for SCA1.


Assuntos
Ataxina-1/genética , Ataxias Espinocerebelares/genética , Quinases Ativadas por p21/genética , Animais , Ataxina-1/antagonistas & inibidores , Cerebelo/metabolismo , Cerebelo/patologia , Modelos Animais de Doenças , Drosophila melanogaster/genética , Inibidores Enzimáticos/administração & dosagem , Técnicas de Silenciamento de Genes , Humanos , Camundongos , Peptídeos/genética , Fosforilação , Proteínas Quinases S6 Ribossômicas 90-kDa/genética , Transdução de Sinais/genética , Ataxias Espinocerebelares/fisiopatologia , Quinases Ativadas por p21/antagonistas & inibidores
9.
Neurobiol Dis ; 116: 69-77, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29753755

RESUMO

Spinocerebellar ataxia type 1 (SCA1) is a fatal inherited neurodegenerative disease. In this study, we demonstrate the label-free optical imaging methodology that can detect, with a high degree of sensitivity, discrete areas of degeneration in the cerebellum of the SCA1 mouse models. We used ATXN1[82Q] and ATXN1[30Q]-D776 mice in which the transgene is directed only to Purkinje cells. Molecular layer, granular layer, and white matter regions are analyzed using the intrinsic contrasts provided by polarization-sensitive optical coherence tomography. Cerebellar atrophy in SCA1 mice occurred both in gray matter and white matter. While gray matter atrophy is obvious, indications of white matter atrophy including different birefringence characteristics, and shortened and contorted branches are observed. Imaging results clearly show the loss or atrophy of myelinated axons in ATXN1[82Q] mice. The method provides unbiased contrasts that can facilitate the understanding of the pathological progression in neurodegenerative diseases and other neural disorders.


Assuntos
Ataxina-1 , Córtex Cerebelar/diagnóstico por imagem , Substância Cinzenta/diagnóstico por imagem , Tomografia de Coerência Óptica/métodos , Substância Branca/diagnóstico por imagem , Animais , Ataxina-1/genética , Atrofia/diagnóstico por imagem , Atrofia/genética , Atrofia/patologia , Córtex Cerebelar/patologia , Substância Cinzenta/patologia , Camundongos , Substância Branca/patologia
10.
Neurobiol Dis ; 116: 93-105, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29758256

RESUMO

Spinocerebellar ataxia type 1 (SCA1) is a polyglutamine (polyQ) repeat neurodegenerative disease in which a primary site of pathogenesis are cerebellar Purkinje cells. In addition to polyQ expansion of ataxin-1 protein (ATXN1), phosphorylation of ATXN1 at the serine 776 residue (ATXN1-pS776) plays a significant role in protein toxicity. Utilizing a biochemical approach, pharmacological agents and cell-based assays, including SCA1 patient iPSC-derived neurons, we examine the role of Protein Kinase A (PKA) as an effector of ATXN1-S776 phosphorylation. We further examine the implications of PKA-mediated phosphorylation at ATXN1-S776 on SCA1 through genetic manipulation of the PKA catalytic subunit Cα in Pcp2-ATXN1[82Q] mice. Here we show that pharmacologic inhibition of S776 phosphorylation in transfected cells and SCA1 patient iPSC-derived neuronal cells lead to a decrease in ATXN1. In vivo, reduction of PKA-mediated ATXN1-pS776 results in enhanced degradation of ATXN1 and improved cerebellar-dependent motor performance. These results provide evidence that PKA is a biologically important kinase for ATXN1-pS776 in cerebellar Purkinje cells.


Assuntos
Ataxia/metabolismo , Ataxina-1/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Células de Purkinje/metabolismo , Serina/metabolismo , Animais , Ataxia/genética , Ataxia/patologia , Ataxina-1/genética , Proteínas Quinases Dependentes de AMP Cíclico/genética , Feminino , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Fosforilação/fisiologia , Células de Purkinje/patologia , Serina/genética
11.
Neuron ; 97(6): 1235-1243.e5, 2018 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-29526553

RESUMO

Polyglutamine (polyQ) diseases are caused by expansion of translated CAG repeats in distinct genes leading to altered protein function. In spinocerebellar ataxia type 1 (SCA1), a gain of function of polyQ-expanded ataxin-1 (ATXN1) contributes to cerebellar pathology. The extent to which cerebellar toxicity depends on its cognate partner capicua (CIC), versus other interactors, remains unclear. It is also not established whether loss of the ATXN1-CIC complex in the cerebellum contributes to disease pathogenesis. In this study, we exclusively disrupt the ATXN1-CIC interaction in vivo and show that it is at the crux of cerebellar toxicity in SCA1. Importantly, loss of CIC in the cerebellum does not cause ataxia or Purkinje cell degeneration. Expression profiling of these gain- and loss-of-function models, coupled with data from iPSC-derived neurons from SCA1 patients, supports a mechanism in which gain of function of the ATXN1-CIC complex is the major driver of toxicity.


Assuntos
Ataxina-1/deficiência , Cerebelo/metabolismo , Mutação com Ganho de Função/fisiologia , Ataxias Espinocerebelares/genética , Ataxias Espinocerebelares/metabolismo , Animais , Ataxina-1/genética , Células Cultivadas , Cerebelo/patologia , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Ataxias Espinocerebelares/patologia
12.
Dis Model Mech ; 11(2)2018 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-29419414

RESUMO

Spinocerebellar ataxia type 1 (SCA1) is characterized by adult-onset cerebellar degeneration with attendant loss of motor coordination. Bulbar function is eventually impaired and patients typically die from an inability to clear the airway. We investigated whether motor neuron degeneration is at the root of bulbar dysfunction by studying SCA1 knock-in (Atxn1154Q/+ ) mice. Spinal cord and brainstem motor neurons were assessed in Atxn1154Q/+ mice at 1, 3 and 6 months of age. Specifically, we assessed breathing physiology, diaphragm histology and electromyography, and motor neuron histology and immunohistochemistry. Atxn1154Q/+ mice show progressive neuromuscular respiratory abnormalities, neurogenic changes in the diaphragm, and motor neuron degeneration in the spinal cord and brainstem. Motor neuron degeneration is accompanied by reactive astrocytosis and accumulation of Atxn1 aggregates in the motor neuron nuclei. This observation correlates with previous findings in SCA1 patient tissue. Atxn1154Q/+ mice develop bulbar dysfunction because of motor neuron degeneration. These findings confirm the Atxn1154Q/+ line as a SCA1 model with face and construct validity for this understudied disease feature. Furthermore, this model is suitable for studying the pathogenic mechanism driving motor neuron degeneration in SCA1 and possibly other degenerative motor neuron diseases. From a clinical standpoint, the data indicate that pulmonary function testing and employment of non-invasive ventilator support could be beneficial in SCA1 patients. The physiological tests used in this study might serve as valuable biomarkers for future therapeutic interventions and clinical trials.This article has an associated First Person interview with the first author of the paper.


Assuntos
Neurônios Motores/patologia , Degeneração Neural/patologia , Degeneração Neural/fisiopatologia , Sistema Respiratório/fisiopatologia , Ataxias Espinocerebelares/patologia , Ataxias Espinocerebelares/fisiopatologia , Envelhecimento/patologia , Animais , Ataxina-1/metabolismo , Diafragma/patologia , Diafragma/fisiopatologia , Gliose/complicações , Gliose/patologia , Nervo Hipoglosso/patologia , Nervo Hipoglosso/fisiopatologia , Corpos de Inclusão Intranuclear/metabolismo , Camundongos , Neurônios Motores/metabolismo , Junção Neuromuscular/patologia , Junção Neuromuscular/fisiopatologia , Agregados Proteicos , Sistema Respiratório/patologia , Medula Espinal/patologia , Medula Espinal/fisiopatologia
13.
Adv Exp Med Biol ; 1049: 135-145, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29427101

RESUMO

Spinocerebellar ataxia type 1 (SCA1) is an adult-onset, inherited disease that leads to degeneration of Purkinje cells of the cerebellum and culminates in death 10-30 years after disease onset. SCA1 is caused by a CAG repeat mutation in the ATXN1 gene, encoding the ATXN1 protein with an abnormally expanded polyglutamine tract. As neurodegeneration progresses, other brain regions become involved and contribute to cognitive deficits as well as problems with speech, swallowing, and control of breathing. The fundamental basis of pathology is an aberration in the normal function of Purkinje cells affecting regulation of gene transcription and RNA splicing. Glutamine-expanded ATXN1 is highly stable and more resistant to degradation. Moreover, phosphorylation at S776 in ATXN1 is a post-translational modification known to influence protein levels. SCA1 remains an untreatable disease managed only by palliative care. Preclinical studies are founded on the principle that mutant protein load is toxic and attenuating ATXN1 protein levels can alleviate disease. Two approaches being pursued are targeting gene expression or protein levels. Viral delivery of miRNAs harnesses the RNAi pathway to destroy ATXN1 mRNA. This approach shows promise in mouse models of disease. At the protein level, kinase inhibitors that block ATXN1-S776 phosphorylation may lead to therapeutic clearance of unphosphorylated ATXN1.


Assuntos
Ataxina-1 , Processamento de Proteína Pós-Traducional , Células de Purkinje , Processamento de RNA , Ataxias Espinocerebelares , Transcrição Genética , Animais , Ataxina-1/biossíntese , Ataxina-1/genética , Terapia Genética/métodos , Humanos , MicroRNAs/genética , MicroRNAs/metabolismo , Fosforilação , Células de Purkinje/metabolismo , Células de Purkinje/patologia , Estabilidade de RNA/genética , Ataxias Espinocerebelares/genética , Ataxias Espinocerebelares/metabolismo , Ataxias Espinocerebelares/patologia , Ataxias Espinocerebelares/terapia
14.
Nat Rev Neurosci ; 18(10): 613-626, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28855740

RESUMO

The dominantly inherited spinocerebellar ataxias (SCAs) are a large and diverse group of neurodegenerative diseases. The most prevalent SCAs (SCA1, SCA2, SCA3, SCA6 and SCA7) are caused by expansion of a glutamine-encoding CAG repeat in the affected gene. These SCAs represent a substantial portion of the polyglutamine neurodegenerative disorders and provide insight into this class of diseases as a whole. Recent years have seen considerable progress in deciphering the clinical, pathological, physiological and molecular aspects of the polyglutamine SCAs, with these advances establishing a solid base from which to pursue potential therapeutic approaches.


Assuntos
Peptídeos/genética , Ataxias Espinocerebelares , Animais , Encéfalo/fisiopatologia , Modelos Animais de Doenças , Humanos , Modelos Genéticos , Modelos Neurológicos , Mutação , Proteínas do Tecido Nervoso/genética , Peptídeos/fisiologia , Ataxias Espinocerebelares/diagnóstico , Ataxias Espinocerebelares/genética , Ataxias Espinocerebelares/fisiopatologia
15.
Nat Genet ; 49(4): 527-536, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28288114

RESUMO

Gain-of-function mutations in some genes underlie neurodegenerative conditions, whereas loss-of-function mutations in the same genes have distinct phenotypes. This appears to be the case with the protein ataxin 1 (ATXN1), which forms a transcriptional repressor complex with capicua (CIC). Gain of function of the complex leads to neurodegeneration, but ATXN1-CIC is also essential for survival. We set out to understand the functions of the ATXN1-CIC complex in the developing forebrain and found that losing this complex results in hyperactivity, impaired learning and memory, and abnormal maturation and maintenance of upper-layer cortical neurons. We also found that CIC activity in the hypothalamus and medial amygdala modulates social interactions. Informed by these neurobehavioral features in mouse mutants, we identified five individuals with de novo heterozygous truncating mutations in CIC who share similar clinical features, including intellectual disability, attention deficit/hyperactivity disorder (ADHD), and autism spectrum disorder. Our study demonstrates that loss of ATXN1-CIC complexes causes a spectrum of neurobehavioral phenotypes.


Assuntos
Ataxina-1/genética , Transtorno do Espectro Autista/genética , Doenças Neurodegenerativas/genética , Proteínas Nucleares/genética , Proteínas Repressoras/genética , Animais , Cerebelo/patologia , Feminino , Humanos , Deficiência Intelectual/genética , Relações Interpessoais , Masculino , Camundongos , Proteínas do Tecido Nervoso/genética , Fenótipo
16.
Neurophotonics ; 4(1): 011006, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27725947

RESUMO

We present the visualization of the mouse cerebellum and adjacent brainstem using a serial optical coherence scanner, which integrates a vibratome slicer and polarization-sensitive optical coherence tomography for ex vivo imaging. The scanner provides intrinsic optical contrasts to distinguish the cerebellar cortical layers and white matter. Images from serial scans reveal the large-scale anatomy in detail and map the nerve fiber pathways in the cerebellum and brainstem. By incorporating a water-immersion microscope objective, we also present high-resolution tiled images that delineate fine structures in the cerebellum and brainstem.

17.
Hum Mol Genet ; 25(23): 5083-5093, 2016 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-28007900

RESUMO

Splicing regulation is an important step of post-transcriptional gene regulation. It is a highly dynamic process orchestrated by RNA-binding proteins (RBPs). RBP dysfunction and global splicing dysregulation have been implicated in many human diseases, but the in vivo functions of most RBPs and the splicing outcome upon their loss remain largely unexplored. Here we report that constitutive deletion of Rbm17, which encodes an RBP with a putative role in splicing, causes early embryonic lethality in mice and that its loss in Purkinje neurons leads to rapid degeneration. Transcriptome profiling of Rbm17-deficient and control neurons and subsequent splicing analyses using CrypSplice, a new computational method that we developed, revealed that more than half of RBM17-dependent splicing changes are cryptic. Importantly, RBM17 represses cryptic splicing of genes that likely contribute to motor coordination and cell survival. This finding prompted us to re-analyze published datasets from a recent report on TDP-43, an RBP implicated in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), as it was demonstrated that TDP-43 represses cryptic exon splicing to promote cell survival. We uncovered a large number of TDP-43-dependent splicing defects that were not previously discovered, revealing that TDP-43 extensively regulates cryptic splicing. Moreover, we found a significant overlap in genes that undergo both RBM17- and TDP-43-dependent cryptic splicing repression, many of which are associated with survival. We propose that repression of cryptic splicing by RBPs is critical for neuronal health and survival. CrypSplice is available at www.liuzlab.org/CrypSplice.


Assuntos
Esclerose Amiotrófica Lateral/genética , Proteínas de Ligação a DNA/genética , Demência Frontotemporal/genética , Degeneração Neural/genética , Proteínas do Tecido Nervoso/genética , Fatores de Processamento de RNA/genética , Esclerose Amiotrófica Lateral/fisiopatologia , Animais , Biologia Computacional/métodos , Modelos Animais de Doenças , Éxons/genética , Demência Frontotemporal/fisiopatologia , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Camundongos , Degeneração Neural/patologia , Proteínas do Tecido Nervoso/biossíntese , Células de Purkinje/metabolismo , Células de Purkinje/patologia , Processamento de RNA/genética , Fatores de Processamento de RNA/biossíntese , Proteínas de Ligação a RNA/biossíntese , Proteínas de Ligação a RNA/genética
18.
Bioessays ; 38(10): 977-80, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27479863

RESUMO

The conventional approach to developing disease-modifying treatments for neurodegenerative conditions has been to identify drivers of pathology and inhibit such pathways. Here we discuss the possibility that the efficacy of such approaches may be increasingly attenuated as disease progresses. This is based on experiments using mouse models of spinocerebellar ataxia type 1 and Huntington's disease (HD), where expression of the dominantly acting mutations could be switched off, as well as studies in human HD, which suggest that the primary genetic driver of age-of-onset of disease is a much weaker determinant of disease progression in affected individuals. The idea that one may approach a point in the disease course where such rational therapeutic strategies based on targets which determine onset of disease have minimal efficacy, suggests that one needs to consider other approaches to therapies and clinical trial design, including initiation of therapies in presymptomatic individuals.


Assuntos
Doença de Huntington/tratamento farmacológico , Ataxias Espinocerebelares/tratamento farmacológico , Animais , Modelos Animais de Doenças , Progressão da Doença , Doença de Huntington/patologia , Camundongos , Prognóstico , Ataxias Espinocerebelares/patologia
19.
Neuron ; 89(6): 1194-1207, 2016 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-26948890

RESUMO

SCA1, a fatal neurodegenerative disorder, is caused by a CAG expansion encoding a polyglutamine stretch in the protein ATXN1. We used RNA sequencing to profile cerebellar gene expression in Pcp2-ATXN1[82Q] mice with ataxia and progressive pathology and Pcp2-ATXN1[30Q]D776 animals having ataxia in absence of Purkinje cell progressive pathology. Weighted Gene Coexpression Network Analysis of the cerebellar expression data revealed two gene networks that significantly correlated with disease and have an expression profile correlating with disease progression in ATXN1[82Q] Purkinje cells. The Magenta Module provides a signature of suppressed transcriptional programs reflecting disease progression in Purkinje cells, while the Lt Yellow Module reflects transcriptional programs activated in response to disease in Purkinje cells as well as other cerebellar cell types. Furthermore, we found that upregulation of cholecystokinin (Cck) and subsequent interaction with the Cck1 receptor likely underlies the lack of progressive Purkinje cell pathology in Pcp2-ATXN1[30Q]D776 mice.


Assuntos
Ataxina-1/genética , Cerebelo/metabolismo , Cerebelo/patologia , Ataxias Espinocerebelares/patologia , Transcriptoma/genética , Animais , Ataxina-1/metabolismo , Quimiocinas CC/deficiência , Quimiocinas CC/genética , Colecistocinina/deficiência , Colecistocinina/genética , Modelos Animais de Doenças , Progressão da Doença , Redes Reguladoras de Genes , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas do Tecido Nervoso/metabolismo , Neuropeptídeos/metabolismo , Proteínas Nucleares/metabolismo , Peptídeos/genética , Peptídeos/metabolismo , Células de Purkinje/metabolismo , Receptor de Colecistocinina B/deficiência , Receptor de Colecistocinina B/genética , Regulação para Cima/genética
20.
Nat Immunol ; 17(2): 187-95, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26726812

RESUMO

Studies of repertoires of mouse monoclonal CD4(+) T cells have revealed several mechanisms of self-tolerance; however, which mechanisms operate in normal repertoires is unclear. Here we studied polyclonal CD4(+) T cells specific for green fluorescent protein expressed in various organs, which allowed us to determine the effects of specific expression patterns on the same epitope-specific T cells. Peptides presented uniformly by thymic antigen-presenting cells were tolerated by clonal deletion, whereas peptides excluded from the thymus were ignored. Peptides with limited thymic expression induced partial clonal deletion and impaired effector T cell potential but enhanced regulatory T cell potential. These mechanisms were also active for T cell populations specific for endogenously expressed self antigens. Thus, the immunotolerance of polyclonal CD4(+) T cells was maintained by distinct mechanisms, according to self-peptide expression patterns.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Expressão Gênica , Tolerância Imunológica , Peptídeos/genética , Peptídeos/imunologia , Sequência de Aminoácidos , Animais , Células Apresentadoras de Antígenos/imunologia , Células Apresentadoras de Antígenos/metabolismo , Autoantígenos/química , Autoantígenos/genética , Autoantígenos/imunologia , Autoimunidade , Deleção Clonal/genética , Deleção Clonal/imunologia , Epitopos de Linfócito T/química , Epitopos de Linfócito T/genética , Epitopos de Linfócito T/imunologia , Feminino , Genes Reporter , Camundongos , Camundongos Transgênicos , Peptídeos/química , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Timo/imunologia , Timo/metabolismo
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