RESUMO
The neuronal ubiquitin/proteasomal pathway has been implicated in the pathogenesis of Alzheimer's disease (AD). We now show that a component of the pathway, ubiquitin C-terminal hydrolase L1 (Uch-L1), is required for normal synaptic and cognitive function. Transduction of Uch-L1 protein fused to the transduction domain of HIV-transactivator protein (TAT) restores normal enzymatic activity and synaptic function both in hippocampal slices treated with oligomeric Abeta and in the APP/PS1 mouse model of AD. Moreover, intraperitoneal injections with the fusion protein improve the retention of contextual learning in APP/PS1 mice over time. The beneficial effect of the Uch-L1 fusion protein is associated with restoration of normal levels of the PKA-regulatory subunit IIalpha, PKA activity, and CREB phosphorylation.
Assuntos
Doença de Alzheimer/fisiopatologia , Precursor de Proteína beta-Amiloide/metabolismo , Memória/fisiologia , Proteínas Recombinantes de Fusão/metabolismo , Transmissão Sináptica/fisiologia , Ubiquitina Tiolesterase/metabolismo , Doença de Alzheimer/enzimologia , Precursor de Proteína beta-Amiloide/genética , Animais , Aprendizagem da Esquiva , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Modelos Animais de Doenças , Potenciais Pós-Sinápticos Excitadores/fisiologia , Medo , Produtos do Gene tat/genética , Produtos do Gene tat/metabolismo , Hipocampo/citologia , Hipocampo/metabolismo , Humanos , Técnicas In Vitro , Potenciação de Longa Duração/fisiologia , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Presenilina-1 , Proteínas Recombinantes de Fusão/genética , Ubiquitina Tiolesterase/genéticaRESUMO
Huntington's disease (HD) is an inherited progressive neurological disorder for which there is no effective therapy. It is caused by a CAG/polyglutamine repeat expansion that leads to abnormal protein aggregation and deposition in the brain. Several compounds have been shown to disrupt the aggregation process in vitro, including a number of benzothiazoles. To further explore the therapeutic potential of the benzothiazole aggregation inhibitors, we assessed PGL-135 and riluzole in hippocampal slice cultures derived from the R6/2 mouse, confirming their ability to inhibit aggregation with an EC50 of 40 microM in this system. Preliminary pharmacological work showed that PGL-135 was metabolically unstable, and therefore, we conducted a preclinical trial in the R6/2 mouse with riluzole. At the maximum tolerated dose, we achieved steady-state riluzole levels of 100 microM in brain. However, this was insufficient to inhibit aggregation in vivo and we found no improvement in the disease phenotype.
Assuntos
Doença de Huntington/tratamento farmacológico , Fármacos Neuroprotetores/farmacocinética , Riluzol/farmacocinética , Tiazóis/metabolismo , Tiazóis/farmacologia , Animais , Benzotiazóis , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Genótipo , Doença de Huntington/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos Transgênicos , Fármacos Neuroprotetores/química , Técnicas de Cultura de Órgãos , Riluzol/química , Tiazóis/químicaRESUMO
Synaptic damage and loss are factors that affect the degree of dementia experienced in Alzheimer disease (AD) patients. Multicolor DiOlistic labeling of the hippocampus has been undertaken which allows the full dendritic arbor of targeted neurons to be imaged. Using this labeling technique the neuronal morphology of two transgenic mouse lines (J20 and APP/PS1) expressing mutant forms of the Amyloid Precursor Protein (APP), at various ages, have been visualized and compared to Wild Type (WT) littermate controls. Swollen bulbous dystrophic neurites with loss of spines were apparent in the transgenic animals. Upon quantification, statistically significant reductions in the number of spines and total dendrite area was observed in both transgenic mouse lines at 11 months of age. Similar morphological abnormalities were seen in human AD hippocampal tissue both qualitatively and quantitatively. Immunohistochemistry and DiOlistic labeling was combined so that Abeta plaques were imaged in relation to the dendritic trees. No preferential localization of these abnormal dystrophic neurites was seen in regions with plaques. DiI labeled reative astrocytes were often apparent in close proximity to A beta plaques.
