RESUMO
Machado-Joseph disease (MJD, also known as spinocerebellar ataxia type 3) is a fatal neurodegenerative disease that impairs control and coordination of movement. Here we tested whether treatment with the histone deacetylase inhibitor sodium valproate (valproate) prevented a movement phenotype that develops in larvae of a transgenic zebrafish model of the disease. We found that treatment with valproate improved the swimming of the MJD zebrafish, affected levels of acetylated histones 3 and 4, but also increased expression of polyglutamine expanded human ataxin-3. Proteomic analysis of protein lysates generated from the treated and untreated MJD zebrafish also predicted that valproate treatment had activated the sirtuin longevity signaling pathway and this was confirmed by findings of increased SIRT1 protein levels and sirtuin activity in valproate treated MJD zebrafish and HEK293 cells expressing ataxin-3 84Q, respectively. Treatment with resveratrol (another compound known to activate the sirtuin pathway), also improved swimming in the MJD zebrafish. Co-treatment with valproate alongside EX527, a SIRT1 activity inhibitor, prevented induction of autophagy by valproate and the beneficial effects of valproate on the movement in the MJD zebrafish, supporting that they were both dependent on sirtuin activity. These findings provide the first evidence of sodium valproate inducing activation of the sirtuin pathway. Further, they indicate that drugs that target the sirtuin pathway, including sodium valproate and resveratrol, warrant further investigation for the treatment of MJD and related neurodegenerative diseases.
Assuntos
Inibidores de Histona Desacetilases/uso terapêutico , Doença de Machado-Joseph/tratamento farmacológico , Sirtuínas/efeitos dos fármacos , Ácido Valproico/uso terapêutico , Acetilação , Animais , Animais Geneticamente Modificados , Ataxina-3/antagonistas & inibidores , Ataxina-3/genética , Ataxina-3/metabolismo , Autofagia/efeitos dos fármacos , Carbazóis/farmacologia , Carbazóis/uso terapêutico , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Sinergismo Farmacológico , Genes Reporter , Células HEK293 , Inibidores de Histona Desacetilases/farmacologia , Histonas/metabolismo , Humanos , Peptídeos/genética , Processamento de Proteína Pós-Traducional , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Resveratrol/farmacologia , Resveratrol/uso terapêutico , Transdução de Sinais , Sirtuína 1/fisiologia , Sirtuínas/fisiologia , Natação , Expansão das Repetições de Trinucleotídeos , Ácido Valproico/farmacologia , Peixe-Zebra , Proteínas de Peixe-Zebra/antagonistas & inibidores , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismoRESUMO
Polyglutamine diseases are a class of neurodegenerative diseases associated with the accumulation of aggregated mutant proteins. We previously developed a class of degradation-inducing agents targeting the ß-sheet-rich structure typical of such aggregates, and we showed that these agents dose-, time-, and proteasome-dependently decrease the intracellular level of mutant huntingtin with an extended polyglutamine tract, which correlates well with the severity of Huntington's disease. Here, we demonstrate that the same agents also deplete other polyglutamine disease-related proteins: mutant ataxin-3 and ataxin-7 in cells from spino-cerebellar ataxia patients, and mutant atrophin-1 in cells from dentatorubral-pallidoluysian atrophy patients. Targeting cross-ß-sheet structure could be an effective design strategy to develop therapeutic agents for multiple neurodegenerative diseases.
Assuntos
Ataxina-3/antagonistas & inibidores , Ataxina-7/antagonistas & inibidores , Doenças Neurodegenerativas/tratamento farmacológico , Fármacos Neuroprotetores/farmacologia , Proteínas Repressoras/antagonistas & inibidores , Ataxina-3/genética , Ataxina-7/genética , Células Cultivadas , Relação Dose-Resposta a Droga , Fibroblastos/efeitos dos fármacos , Humanos , Estrutura Molecular , Doenças Neurodegenerativas/genética , Doenças Neurodegenerativas/patologia , Fármacos Neuroprotetores/síntese química , Fármacos Neuroprotetores/química , Proteínas Repressoras/genética , Relação Estrutura-AtividadeRESUMO
BACKGROUND: We have previously demonstrated the neuroprotective activity of tetracycline on a Spinocerebellar Ataxia 3 nematode model. Here, we present the screening of a small library of tetracycline congeners in order to identify the most effective compound in preventing ataxin-3 aggregation. METHODS: We performed the assays on the Josephin Domain as it is directly involved in the onset of fibrillation. We used thioflavin T and solubility assays to spot out the most effective tetracycline congeners; Fourier transform infrared and NMR spectroscopies to characterize their mode of action. We employed an ataxic Caenorhabditis elegans model to evaluate the pharmacological efficacy of tetracycline congeners. RESULTS: Methacycline was identified as the most effective compound. Like tetracycline, methacycline neither significantly affected the aggregation kinetics nor did it change the secondary structures of the final aggregates but increased the solubility of the aggregated species. Saturation transfer NMR experiments demonstrated methacycline capability to only bind the oligomeric species of Josephin Domain. Competition assays also showed that methacycline binds to the Josephin Domain more tightly than tetracycline. The treatment with methacycline induced a significant improvement in motility and locomotion of the transgenic C. elegans without changing its lifespan. The efficacy was distinctly stronger than that of tetracycline. Noteworthy, unlike tetracycline, methacycline was able to retard aging-related decline in motility of even the healthy worms used. CONCLUSIONS: The apparent absence of toxic effects displayed by methacycline, along with its stronger efficacy in contrasting expanded ataxin-3 toxicity, makes it a possible candidate for a chronic treatment of the disease.