RESUMO
Structural conversion of cellular prion protein (PrPC) into scrapie PrP (PrPSc) and subsequent aggregation are key events associated with the onset of transmissible spongiform encephalopathies (TSEs). Experimental evidence supports the role of nucleic acids (NAs) in assisting this conversion. Here, we asked whether PrP undergoes liquid-liquid phase separation (LLPS) and if this process is modulated by NAs. To this end, two 25-mer DNA aptamers, A1 and A2, were selected against the globular domain of recombinant murine PrP (rPrP90-231) using SELEX methodology. Multiparametric structural analysis of these aptamers revealed that A1 adopts a hairpin conformation. Aptamer binding caused partial unfolding of rPrP90-231 and modulated its ability to undergo LLPS and fibrillate. In fact, although free rPrP90-231 phase separated into large droplets, aptamer binding increased the number of droplets but noticeably reduced their size. Strikingly, a modified A1 aptamer that does not adopt a hairpin structure induced formation of amyloid fibrils on the surface of the droplets. We show here that PrP undergoes LLPS, and that the PrP interaction with NAs modulates phase separation and promotes PrP fibrillation in a NA structure and concentration-dependent manner. These results shed new light on the roles of NAs in PrP misfolding and TSEs.
Assuntos
Amiloide/metabolismo , Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/metabolismo , Extração Líquido-Líquido/métodos , Doenças Priônicas/patologia , Proteínas Priônicas/química , Proteínas Priônicas/metabolismo , Animais , Camundongos , Conformação de Ácido Nucleico , Doenças Priônicas/metabolismo , Proteínas Priônicas/isolamento & purificação , Ligação Proteica , Conformação Proteica , Dobramento de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Técnica de Seleção de AptâmerosRESUMO
Resumen: La enfermedad de Creutzfeldt-Jakob (ECJ) es una patología neurodegenerativa transmisible, producida por una proteína anómala infectante denominada prion. Junto con el kuru, el insomnio familiar fatal y el síndrome de Gerstmann-Stráussler-Scheinker, configura el grupo de las llamadas encefalopatías espongiformes. La ECJ es la forma más común en el ser humano: se calcula que afecta a una persona por cada millón, a nivel mundial, y la mayoría de los pacientes presenta síntomas clásicos de demencia y mioclonías, asociadas a cambios específicos en el electroencefalograma (EEG). Conforme la enfermedad progresa, el cuadro demencial empeora y pueden presentarse síntomas visuales, cerebelosos, piramidales y extrapiramidales. El diagnóstico definitivo se logra demostrando la degeneración espongiforme de las neuronas en histopatología. La ECJ siempre es mortal y no tiene tratamiento específico: cerca del 90% de los pacientes fallece dentro del primer año después del diagnóstico. En este artículo, se reporta el caso de un paciente con ECJ esporádica probable, de acuerdo con los criterios diagnósticos actuales de la OMS y se da a conocer una revisión de la literatura.
Abstract: Creutzfeldt-Jakob disease (CJD) is a transmissible neurodegenerative pathology produced by an infecting abnormal protein called prion. Together with kuru, fatal familial insomnia, and Gerstmann-Stráussler-Scheinker syndrome, it forms the group of so-called spongiform encephalopathies. CJD is the most common form in humans: it is estimated to affect one person per million worldwide and most patients have classic symptoms of dementia and myoclonus, associated with specific changes in the electroencephalogram (EEG). As the disease progresses, the dementia condition worsens and visual, cerebellar, pyramidal, and extrapyramidal symptoms may develop. The final diagnosis is achieved by proving the spongiform degeneration of neurons in the histopathology. CJD is always fatal and has no specific treatment: about 90 % of patients die within the first year of diagnosis. This article reports the case of a patient with probable sporadic CJD, following current who diagnostic criteria, and provides a literature review.
Resumo: A doença de Creutzfeldt-Jakob (DCJ) é uma doença patologia neurodegenerativa transmissível, produzida por uma proteína anormal infectante denominada prion. Juntamente com o kuru, a Insónia familiar fatal e a síndrome de Gerstmann-Stráussler-Scheinker, forma o grupo das chamadas encefalopatias espongiformes. A DCJ é a forma mais comum em humanos: estima-se que ela afete uma em cada um milhão de pessoas em todo o mundo, e a maioria dos pacientes apresenta sintomas clássicos de demência e mioclonia, associados a alterações específicas no eletroencefalograma (EEG). À medida que a doença progride, o quadro de demência piora e podem surgir sintomas visuais, ce-rebelares, piramidais e extrapiramidais. O diagnóstico definitivo é obtido por meio da demonstração da degeneração espongiforme dos neurónios na histopatologia. A dcj é sempre fatal e não possui tratamento específico: cerca de 90% dos pacientes morrem no primeiro ano após o diagnóstico. Neste artigo, é relatado o caso de um paciente com dcj esporádica provável, de acordo com os atuais critérios de diagnóstico da oms, e é apresentada uma revisão da literatura.
Assuntos
Humanos , Masculino , Pessoa de Meia-Idade , Síndrome de Creutzfeldt-Jakob , Doenças Priônicas/patologia , Demência , MiocloniaRESUMO
Because enriched environment (EE) and exercise increase and aging decreases immune response, we hypothesized that environmental enrichment and aging will, respectively, delay and increase prion disease progression. Mice dorsal striatum received bilateral stereotaxic intracerebral injections of normal or ME7 prion infected mouse brain homogenates. After behavior analysis, animals were euthanized and their brains processed for astrocyte GFAP immunolabeling. Our analysis related to the environmental influence are limited to young adult mice, whereas age influence refers to aged mice raised on standard cages. Burrowing activity began to reduce in ME7-SE two weeks before ME7-EE, while no changes were apparent in ME7 aged mice (ME7-A). Object placement recognition was impaired in ME7-SE, NBH-A, and ME7-A but normal in all other groups. Object identity recognition was impaired in ME7-A. Cluster analysis revealed two morphological families of astrocytes in NBH-SE animals, three in NBH-A and ME7-A, and four in NBH-EE, ME7-SE, and ME7-EE. As compared with control groups, astrocytes from DG and CA3 prion-diseased animals show significant numerical and morphological differences and environmental enrichment did not reverse these changes but induced different morphological changes in GFAP+ hippocampal astroglia. We suggest that environmental enrichment and aging delayed hippocampal-dependent behavioral and neuropathological signs of disease progression.
Assuntos
Envelhecimento/fisiologia , Astrócitos/patologia , Comportamento Animal , Encéfalo/patologia , Meio Ambiente , Hipocampo/patologia , Doenças Priônicas/patologia , Doenças Priônicas/psicologia , Animais , Modelos Animais de Doenças , Progressão da Doença , Técnicas Imunoenzimáticas , Masculino , CamundongosRESUMO
We investigated possible interaction between an arbovirus infection and the ME7 induced mice prion disease. C57BL/6, females, 6-week-old, were submitted to a bilateral intrahippocampal injection of ME7 prion strain (ME7) or normal brain homogenate (NBH). After injections, animals were organized into two groups: NBH (n = 26) and ME7 (n = 29). At 15th week after injections (wpi), animals were challenged intranasally with a suspension of Piry arbovirus 0.001% or with NBH. Behavioral changes in ME7 animals appeared in burrowing activity at 14 wpi. Hyperactivity on open field test, errors on rod bridge, and time reduction in inverted screen were detected at 15th, 19th, and 20th wpi respectively. Burrowing was more sensitive to earlier hippocampus dysfunction. However, Piry-infection did not significantly affect the already ongoing burrowing decline in the ME7-treated mice. After behavioral tests, brains were processed for IBA1, protease-resistant form of PrP, and Piry virus antigens. Although virus infection in isolation did not change the number of microglia in CA1, virus infection in prion diseased mice (at 17th wpi) induced changes in number and morphology of microglia in a laminar-dependent way. We suggest that virus infection exacerbates microglial inflammatory response to a greater degree in prion-infected mice, and this is not necessarily correlated with hippocampal-dependent behavioral deficits.
Assuntos
Arbovírus/patogenicidade , Região CA1 Hipocampal/virologia , Coinfecção , Encefalite por Arbovirus/complicações , Microglia/virologia , Doenças Priônicas/complicações , Animais , Antígenos Virais/imunologia , Arbovírus/imunologia , Comportamento Animal , Região CA1 Hipocampal/imunologia , Região CA1 Hipocampal/patologia , Região CA1 Hipocampal/fisiopatologia , Proteínas de Ligação ao Cálcio/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Encefalite por Arbovirus/imunologia , Encefalite por Arbovirus/patologia , Encefalite por Arbovirus/psicologia , Feminino , Camundongos Endogâmicos C57BL , Proteínas dos Microfilamentos/metabolismo , Microglia/imunologia , Microglia/patologia , Atividade Motora , Degeneração Neural , Doenças Priônicas/patologia , Doenças Priônicas/psicologia , Fatores de TempoRESUMO
Prion diseases are a group of rare and rapidly progressive neurodegenerative conditions that may cause neuropsychiatric symptoms. This group of diseases has been described since the 18(th) century, but they were recognized decades later, when it became clear that the humans were affected by infected animals. There was controversy when the problem was attributed to a single protein with infective capacity. The common pathological process is characterized by the conversion of the normal cellular prion protein into an abnormal form. In humans, the illness has been classified as idiopathic, inherited and acquired through exposure to exogenous material containing abnormal prions. The most prominent neurological manifestation of prion diseases is the emergence of a rapidly progressive dementia, mioclonus associated with cerebellar ataxia and also extra pyramidal symptoms. Psychiatric symptoms occur in early stages of the illness and can contribute to timely diagnosis of this syndrome. Psychiatric symptoms have traditionally been grouped in three categories: affective symptoms, impaired motor function and psychotic symptoms. Such events usually occur during the prodromal period prior to the neurological manifestations and consists in the presence of social isolation, onset of delusions, irritability/aggression, visual hallucinations, anxiety and depression, and less frequent first-rank symptoms among others. Definite diagnosis requires post mortem examination. The possibility that a large number of cases may occur in the next years or that many cases have not been considered with this diagnosis is a fact. In our opinion, psychiatrists should be aware of symptoms of this disease. The main objective of this research consisted of assessing the correlation between this disturbance and neuro-psychiatric symptoms and particularly if this psychiatric manifestations integrate a clinical picture suggestive for the diagnosis of these diseases, but firstly reviewed taxonomic, pathogenic and pathological aspects. The authors of this project also added an element in relation to some diagnostic considerations based on scientific evidence. For the search controlled descriptors applied to the research for indexing scientific articles in databases were used. The electronic data bases used were PubMed, EMBASE and also PsycInfo. The descriptors were prion diseases, psychotic disorders, depression, mood disorders, pathology, classification, prion protein, history, neurological manifestations, and psychiatric manifestations. The selection criteria for the material were qualitative. To conclude, and based on the extensive literature review, the authors propose that the period where the evidence is more robust for mental impaired is named "psychiatric symptoms phase, which can be extended for a few months, being the psychiatric affective symptoms the most characteristic of this phase. In conclusion, we considered that the identification of these symptoms in a patient with risk factors for developing the disease will contribute to the early identification, and would regulate the guidelines in suspected diagnosis of this group of disorders. The intention is provide a better quality of life to the sick people.
Assuntos
Transtornos Mentais/etiologia , Doenças Priônicas/psicologia , Humanos , Transtornos Mentais/diagnóstico , Transtornos Mentais/terapia , Doenças Priônicas/diagnóstico , Doenças Priônicas/patologia , Doenças Priônicas/terapiaRESUMO
Behavioral and neuropathological changes have been widely investigated in murine prion disease but stereological based unbiased estimates of key neuropathological features have not been carried out. After injections of ME7 infected (ME7) or normal brain homogenates (NBH) into dorsal CA1 of albino Swiss mice and C57BL6, we assessed behavioral changes on hippocampal-dependent tasks. We also estimated by optical fractionator at 15 and 18 weeks post-injections (w.p.i.) the total number of neurons, reactive astrocytes, activated microglia and perineuronal nets (PN) in the polymorphic layer of dentate gyrus (PolDG), CA1 and septum in albino Swiss mice. On average, early behavioral changes in albino Swiss mice start four weeks later than in C57BL6. Cluster and discriminant analysis of behavioral data in albino Swiss mice revealed that four of nine subjects start to change their behavior at 12 w.p.i. and reach terminal stage at 22 w.p.i and the remaining subjects start at 22 w.p.i. and reach terminal stage at 26 w.p.i. Biotinylated dextran-amine BDA-tracer experiments in mossy fiber pathway confirmed axonal degeneration, and stereological data showed that early astrocytosis, microgliosis and reduction in the perineuronal nets are independent of a change in the number of neuronal cell bodies. Statistical analysis revealed that the septal region had greater levels of neuroinflammation and extracellular matrix damage than CA1. This stereological and multivariate analysis at early stages of disease in an outbred model of prion disease provided new insights connecting behavioral changes and neuroinflammation and seems to be important to understand the mechanisms of prion disease progression.
Assuntos
Comportamento Animal , Neurônios/patologia , Doenças Priônicas/patologia , Doenças Priônicas/psicologia , Animais , Modelos Animais de Doenças , Feminino , Gliose/metabolismo , Gliose/patologia , Camundongos , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Microglia/patologiaRESUMO
Inherited prion diseases are characterized by mutations in the PRNP gene encoding the prion protein (PrP). We report a novel missense mutation in the PRNP gene (resulting in a G114V mutation in PrP) in members of a Uruguayan family with clinical and histopathologic features of prion disease. Affected individuals were characterized by an early age at onset, initial neuropsychiatric symptoms, late dementia with prominent pyramidal and extrapyramidal symptoms, and long disease duration.
Assuntos
Amiloide/genética , Encéfalo/fisiopatologia , Predisposição Genética para Doença/genética , Mutação/genética , Doenças Priônicas/genética , Precursores de Proteínas/genética , Adolescente , Adulto , Idade de Início , Substituição de Aminoácidos/genética , Biópsia , Encéfalo/metabolismo , Encéfalo/patologia , Aberrações Cromossômicas , Análise Mutacional de DNA , Demência/genética , Demência/patologia , Demência/fisiopatologia , Progressão da Doença , Evolução Fatal , Feminino , Lobo Frontal/metabolismo , Lobo Frontal/patologia , Lobo Frontal/fisiopatologia , Testes Genéticos , Humanos , Masculino , Transtornos da Personalidade/genética , Transtornos da Personalidade/patologia , Transtornos da Personalidade/fisiopatologia , Doenças Priônicas/patologia , Doenças Priônicas/fisiopatologia , Proteínas Priônicas , Príons , Tratos Piramidais/metabolismo , Tratos Piramidais/patologia , Tratos Piramidais/fisiopatologia , UruguaiRESUMO
Nitric oxide (NO) has been implicated in neurotoxicity and cerebral blood flow changes in chronic neurodegeneration, but its activity in the mammalian prion diseases has not been studied in detail. Nicotine adenine dinucleotide phosphate (NADPH)-diaphorase (NADPH-d) histochemistry is a simple and robust histochemical procedure that allows localization of the tissue distribution of NO synthases. The aim of the present study is to assess whether NADPH-d histochemical activity is altered in the hippocampus in the ME7 model of prion disease in C57BL/6J mice. At early and late stages after the initiation of the disease we assessed features of the NADPH-d positive cells and the neuropil histochemical activity in CA1 and dentate gyrus using densitometric analysis. In C57BL/6J mice 13 weeks postinjection of the prion agent ME7, when behavioural changes first become apparent, neuropil NADPH-d histochemical staining increases, whereas at late stages it decreases dramatically. Both type I and type II NADPH-d positive cells were found to survive throughout the hippocampal formation into the late stages of the disease, but diaphorase activity was reduced in dendritic branches and abnormal varicosities were present in both dendritic and axonal processes of NADPH-d positive type I cells. The pathophysiological implications of the results remain to be investigated but both blood flow alteration and NO neurotoxicity may be features of the disease.
Assuntos
Hipocampo/patologia , NADPH Desidrogenase/metabolismo , Neurônios/patologia , Neurópilo/patologia , Doenças Priônicas/patologia , Algoritmos , Animais , Contagem de Células , Dendritos/metabolismo , Dendritos/patologia , Densitometria , Hipocampo/metabolismo , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Neurópilo/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/biossíntese , Óxido Nítrico Sintase Tipo I , Doenças Priônicas/metabolismo , Fluxo Sanguíneo Regional/fisiologia , Sinapses/fisiologia , Fixação de TecidosRESUMO
Transmissible spongiform encephalopathies (TSE) are attributed to the conversion of the cellular prion protein (PrP(c)) into an abnormal isoform (PrP(sc)). This can be caused by the invasion of living organisms by infectious particles, or be inherited due to mutations on the PrP(c) gene. One of the most intriguing problems of prion biology is the inability to generate the infectious agent in vitro. This argues strongly that other cellular proteins besides those added in test tubes or found in cellular preparations are necessary for infection. Despite recent progress in the understanding of prion pathology, the subcellular compartments in which the interaction and conversion of PrP(c) into PrP(sc) take place are still controversial. PrP(c) interacts with various macromolecules at the cell membrane, in endocytic compartments and in the secretory pathway, all of which may play specific roles in the internalisation of PrP(sc) and conversion of PrP(c). A specific interacting protein required for the propagation of prions was originally proposed as a prion receptor, and later referred to as a ligand, a cofactor, protein X, or a partner. However, current studies indicate that PrP(c) associates with multi-molecular complexes, which mediate a variety of functions in distinct cellular compartments. It is proposed that a deeper understanding of the mechanics of such interactions, coupled to a better knowledge of the corresponding signalling pathways and ensuing cellular responses, will have a major impact on the prevention and treatment of TSE.
Assuntos
Proteínas PrPC/metabolismo , Proteínas PrPSc/patogenicidade , Doenças Priônicas/metabolismo , Receptores de Superfície Celular/metabolismo , Humanos , Proteínas PrPSc/metabolismo , Doenças Priônicas/patologia , Isoformas de Proteínas , Transdução de Sinais/imunologiaRESUMO
The AIDS or HIV associated dementia is a cognitive-motor disease, characterized by a strong deficit of several cognitive processes such as attention, memory, sensory perception, motor control among others. The HIV associated dementia affects 30% of adult to 50% of infant HIV positive subjects. Since neurons are not infected by HIV, its principal target in the brain is microglia. The pathophysiology of this syndrome, therefore, remains to be disclosed. Several hypothesis have been proposed, one of them suggests that opportunistic infections can affect the brain. Another hypothesis suggests that microglia secretes toxic products as a result of HIV infection and those are the ones causing the damage and finally, the hypothesis, suggesting that the brain is damaged as a result of the insult caused by HIV-derived proteins. In vitro studies suggest that the HIVgp120, a viral surface protein, is highly neurotoxic. For example HIVgp120 increases cytoplasmic Ca+2 by two ways: facilitating glutamate neurotransmission increasing Ca+2 conductance, and activating the IP3 pathway, facilitating Ca+2 release from the smooth endoplasmic reticulum. This Ca+2 in turn, activates several internal signaling pathways such as the MAPK pathway. We use an animal model to test the HIVgp120 effect on neurophysiological signals and behavior as well as several pharmacological approaches to prevent the HIVgp120 neurotoxic effects. This review updates with the most recent literature discussing the potential mechanisms implicated in the pathophysiology of the AIDS dementia complex. We, in addition, hope the reader will be able to correlate the clinical symptoms observed in the HIV infected subjects and the HIVgp120-induced behavioral changes observed in animal models. Likewise, we discuss the new drugs we are testing, in order to offer a new pharmacological treatment to the patient.