RESUMEN
C-terminus of HSP70 interacting protein (CHIP) is an E3 ubiquitin ligase and HSP70 cochaperone. Mutations in the CHIP encoding gene are the cause of two neurodegenerative conditions: spinocerebellar ataxia autosomal dominant type 48 (SCA48) and autosomal recessive type 16 (SCAR16). The mechanisms underlying CHIP-associated diseases are currently unknown. Mitochondrial dysfunction, specifically dysfunction in mitochondrial autophagy (mitophagy), is increasingly implicated in neurodegenerative diseases and loss of CHIP has been demonstrated to result in mitochondrial dysfunction in multiple animal models, although how CHIP is involved in mitophagy regulation has been previously unknown. Here, we demonstrate that CHIP acts as a negative regulator of the PTEN-induced kinase 1 (PINK1)/Parkin-mediated mitophagy pathway, promoting the degradation of PINK1, impairing Parkin translocation to the mitochondria, and suppressing mitophagy in response to mitochondrial stress. We also show that loss of CHIP enhances neuronal mitophagy in a PINK1 and Parkin dependent manner in Caenorhabditis elegans. Furthermore, we find that multiple disease-associated mutations in CHIP dysregulate mitophagy both in vitro and in vivo in C. elegans neurons, a finding which could implicate mitophagy dysregulation in CHIP-associated diseases.
Asunto(s)
Caenorhabditis elegans , Mitofagia , Mutación , Proteínas Quinasas , Ubiquitina-Proteína Ligasas , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismo , Mitofagia/fisiología , Mitofagia/genética , Animales , Humanos , Proteínas Quinasas/metabolismo , Proteínas Quinasas/genética , Mitocondrias/metabolismo , Mitocondrias/genética , Neuronas/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismoRESUMEN
Accumulation of α-synuclein into toxic oligomers or fibrils is implicated in dopaminergic neurodegeneration in Parkinson's disease. Here we performed a high-throughput, proteome-wide peptide screen to identify protein-protein interaction inhibitors that reduce α-synuclein oligomer levels and their associated cytotoxicity. We find that the most potent peptide inhibitor disrupts the direct interaction between the C-terminal region of α-synuclein and CHarged Multivesicular body Protein 2B (CHMP2B), a component of the Endosomal Sorting Complex Required for Transport-III (ESCRT-III). We show that α-synuclein impedes endolysosomal activity via this interaction, thereby inhibiting its own degradation. Conversely, the peptide inhibitor restores endolysosomal function and thereby decreases α-synuclein levels in multiple models, including female and male human cells harboring disease-causing α-synuclein mutations. Furthermore, the peptide inhibitor protects dopaminergic neurons from α-synuclein-mediated degeneration in hermaphroditic C. elegans and preclinical Parkinson's disease models using female rats. Thus, the α-synuclein-CHMP2B interaction is a potential therapeutic target for neurodegenerative disorders.
Asunto(s)
Enfermedad de Parkinson , Masculino , Femenino , Animales , Ratas , Humanos , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/metabolismo , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismo , Caenorhabditis elegans/metabolismo , Neuronas Dopaminérgicas/metabolismo , Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Péptidos/farmacología , Péptidos/metabolismoRESUMEN
The purpose of the present study was to investigate whether participants with intellectual impairments could benefit from the movement associated with animated pictures while they were learning symbol names. Sixteen school students, whose linguistic-developmental age ranged from 38?91 months, participated in the experiment. They were taught 16 static visual symbols and the corresponding action words (naming task) in two sessions conducted one week apart. In the experimental condition, animation was employed to facilitate comprehension, whereas no animation was used in the control condition. Enhancement of learning was shown in the experimental condition, suggesting that the participants benefited from animated symbols. Furthermore, it was found that the lower the linguistic developmental age, the more effective the animated cue was in learning static visual symbols.
Asunto(s)
Instrucción por Computador/métodos , Niños con Discapacidad/rehabilitación , Educación de las Personas con Discapacidad Intelectual/métodos , Discapacidad Intelectual/rehabilitación , Semántica , Adolescente , Pueblo Asiatico , Niño , Niños con Discapacidad/psicología , Humanos , Discapacidad Intelectual/psicología , Trastornos de la Destreza Motora/psicología , Trastornos de la Destreza Motora/rehabilitación , Estimulación Luminosa , SimbolismoRESUMEN
BACKGROUND: Parkinson's disease is a disabling neurodegenerative movement disorder characterized by dopaminergic neuron loss induced by α-synuclein oligomers. There is an urgent need for disease-modifying therapies for Parkinson's disease, but drug discovery is challenged by lack of in vivo models that recapitulate early stages of neurodegeneration. Invertebrate organisms, such as the nematode worm Caenorhabditis elegans, provide in vivo models of human disease processes that can be instrumental for initial pharmacological studies. METHODS: To identify early motor impairment of animals expressing α-synuclein in dopaminergic neurons, we first used a custom-built tracking microscope that captures locomotion of single C. elegans with high spatial and temporal resolution. Next, we devised a method for semi-automated and blinded quantification of motor impairment for a population of simultaneously recorded animals with multi-worm tracking and custom image processing. We then used genetic and pharmacological methods to define the features of early motor dysfunction of α-synuclein-expressing C. elegans. Finally, we applied the C. elegans model to a drug repurposing screen by combining it with an artificial intelligence platform and cell culture system to identify small molecules that inhibit α-synuclein oligomers. Screen hits were validated using in vitro and in vivo mammalian models. RESULTS: We found a previously undescribed motor phenotype in transgenic α-synuclein C. elegans that correlates with mutant or wild-type α-synuclein protein levels and results from dopaminergic neuron dysfunction, but precedes neuronal loss. Together with artificial intelligence-driven in silico and in vitro screening, this C. elegans model identified five compounds that reduced motor dysfunction induced by α-synuclein. Three of these compounds also decreased α-synuclein oligomers in mammalian neurons, including rifabutin which has not been previously investigated for Parkinson's disease. We found that treatment with rifabutin reduced nigrostriatal dopaminergic neurodegeneration due to α-synuclein in a rat model. CONCLUSIONS: We identified a C. elegans locomotor abnormality due to dopaminergic neuron dysfunction that models early α-synuclein-mediated neurodegeneration. Our innovative approach applying this in vivo model to a multi-step drug repurposing screen, with artificial intelligence-driven in silico and in vitro methods, resulted in the discovery of at least one drug that may be repurposed as a disease-modifying therapy for Parkinson's disease.
Asunto(s)
Trastornos Motores , alfa-Sinucleína , Animales , Inteligencia Artificial , Caenorhabditis elegans/metabolismo , Modelos Animales de Enfermedad , Dopamina/metabolismo , Neuronas Dopaminérgicas/metabolismo , Mamíferos/metabolismo , Trastornos Motores/metabolismo , Ratas , alfa-Sinucleína/metabolismoRESUMEN
The SAX-3/roundabout (Robo) receptor has SLT-1/Slit-dependent and -independent functions in guiding cell and axon migrations. We identified enhancer of ventral-axon guidance defects of unc-40 mutants (EVA-1) as a Caenorhabditis elegans transmembrane receptor for SLT-1. EVA-1 has two predicted galactose-binding ectodomains, acts cell-autonomously for SLT-1/Slit-dependent axon migration functions of SAX-3/Robo, binds to SLT-1 and SAX-3, colocalizes with SAX-3 on cells, and provides cell specificity to the activation of SAX-3 signaling by SLT-1. Double mutants of eva-1 or slt-1 with sax-3 mutations suggest that SAX-3 can (when slt-1 or eva-1 function is reduced) inhibit a parallel-acting guidance mechanism, which involves UNC-40/deleted in colorectal cancer.