RESUMO
The toxic conformer of amyloid ß-protein (Aß) ending at 42 (Aß42), which contains a unique turn conformation at amino acid residue positions 22 and 23 and tends to form oligomers that are neurotoxic, was reported to play a critical role in the pathomechanisms of Alzheimer's disease (AD), in which diabetes mellitus (DM)-like mechanisms are also suggested to be operative. It remains to be established whether the attenuation of insulin signaling is involved in an increase of toxic Aß42 conformer levels. The present study investigated the association between impaired insulin metabolism and formation of toxic Aß42 conformers in the brains of an AD mouse model. In particular, we studied whether insulin deficiency or resistance affected the formation of toxic Aß42 conformers in vivo. We induced insulin deficiency and resistance in 3xTg-AD mice, a mouse AD model harboring two familial AD-mutant APP (KM670/671NL) and PS1 (M146 V) genes and a mutant TAU (P301L) gene, by streptozotocin (STZ) injection and a high fructose diet (HFuD), respectively. Cognitive impairment was significantly worsened by STZ injection but not by HFuD. Dot blot analysis revealed significant increases in total Aß42 levels and the ratio of toxic Aß42 conformer/total Aß42 in STZ-treated mice compared with control and HFuD-fed mice. Immunostaining showed the accumulation of toxic Aß42 conformers and hyper-phosphorylated tau protein (p-tau), which was more prominent in the cortical and hippocampal neurons of STZ-treated mice compared with HFuD-fed and control mice. HFuD-fed mice showed only a mild-to-moderate increase of these proteins compared with controls. Toxic Aß42 conformers were co-localized with p-tau oligomers (Pearson's correlation coefficient = 0.62) in the hippocampus, indicating their co-aggregation. Toxic Aß42 conformer levels were inversely correlated with pancreatic insulin secretion capacity as shown by fasting immunoreactive insulin levels in STZ-treated mice (correlation coefficient = -0.5879, p = .04441), but not HFuD-fed mice, suggesting a decrease in serum insulin levels correlates with toxic Aß42 conformer formation. Levels of p-Akt and phosphorylated glycogen synthase kinase-3ß measured by a homogeneous time-resolved fluorescence assay were significantly lower in STZ-treated mice than in HFuD-fed mice, suggesting a greater inhibition of brain insulin signaling by STZ than HFuD, although both levels were significantly decreased in these groups compared with controls. Iba1-positive and NOS2-positive areas in the cortex and hippocampus were significantly increased in STZ-treated mice and to a lesser extent in HFuD-fed mice compared with controls. These findings suggest that insulin deficiency rather than insulin resistance and the resultant impairment of brain insulin signaling facilitates the formation of toxic Aß42 conformer and its co-aggregation with p-tau oligomers, and that insulin deficiency is an important pathogenic factor in the progression of AD.
Assuntos
Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Disfunção Cognitiva/metabolismo , Proteínas tau/metabolismo , Doença de Alzheimer/genética , Animais , Encéfalo/metabolismo , Disfunção Cognitiva/genética , Modelos Animais de Doenças , Insulina/metabolismo , Camundongos Transgênicos , Neurônios/metabolismo , Fragmentos de Peptídeos/metabolismoRESUMO
Peripheral and CNS inflammation leads to aberrations in developmental and postnatal neurogenesis, yet little is known about the mechanism linking inflammation to neurogenic abnormalities. Specific miRs regulate peripheral and CNS inflammatory responses. miR-155 is the most significantly upregulated miR in primary murine microglia stimulated with lipopolysaccharide (LPS), a proinflammatory Toll-Like Receptor 4 ligand. Here, we demonstrate that miR-155 is essential for robust IL6 gene induction in microglia under LPS stimulation in vitro. LPS-stimulated microglia enhance astrogliogenesis of cocultured neural stem cells (NSCs), whereas blockade of IL6 or genetic ablation of microglial miR-155 restores neural differentiation. miR-155 knock-out mice show reversal of LPS-induced neurogenic deficits and microglial activation in vivo. Moreover, mice with transgenic elevated expression of miR-155 in nestin-positive neural and hematopoietic stem cells, including microglia, show increased cell proliferation and ectopically localized doublecortin-positive immature neurons and radial glia-like cells in the hippocampal dentate gyrus (DG) granular cell layer. Microglia have proliferative and neurogenic effects on NSCs, which are significantly altered by microglial miR-155 overexpression. In addition, miR-155 elevation leads to increased microglial numbers and amoeboid morphology in the DG. Our study demonstrates that miR-155 is essential for inflammation-induced neurogenic deficits via microglial activation and induction of IL6 and is sufficient for disrupting normal hippocampal development.
Assuntos
Regulação da Expressão Gênica/genética , Hipocampo/patologia , Inflamação/genética , Inflamação/patologia , MicroRNAs/metabolismo , Neurogênese/genética , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Técnicas de Cultura de Células , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Técnicas de Cocultura , Modelos Animais de Doenças , Doxiciclina/farmacologia , Embrião de Mamíferos , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Proteína Glial Fibrilar Ácida/metabolismo , Hipocampo/efeitos dos fármacos , Inflamação/induzido quimicamente , Interleucina-6/genética , Interleucina-6/imunologia , Interleucina-6/metabolismo , Lipopolissacarídeos/toxicidade , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , MicroRNAs/genética , Proteínas dos Microfilamentos/metabolismo , Nestina/genética , Nestina/metabolismo , Neurogênese/efeitos dos fármacos , GravidezRESUMO
Tau-tubulin kinase-1 (TTBK1) is a central nervous system (CNS)-specific protein kinase implicated in the pathological phosphorylation of tau. TTBK1-transgenic mice show enhanced neuroinflammation in the CNS. Double-transgenic mice expressing TTBK1 and frontotemporal dementia with parkinsonism-17-linked P301L (JNPL3) tau mutant (TTBK1/JNPL3) show increased accumulation of oligomeric tau protein in the CNS and enhanced loss of motor neurons in the ventral horn of the lumbar spinal cord. To determine the role of TTBK1-induced neuroinflammation in tauopathy-related neuropathogenesis, age-matched TTBK1/JNPL3, JNPL3, TTBK1, and non-transgenic littermates were systematically characterized. There was a striking switch in the activation phenotype and population of mononuclear phagocytes (resident microglia and infiltrating macrophages) in the affected spinal cord region: JNPL3 mice showed accumulation of alternatively activated microglia, whereas TTBK1 and TTBK1/JNPL3 mice showed accumulation of classically activated infiltrating peripheral monocytes. In addition, expression of chemokine ligand 2, a chemokine important for the recruitment of peripheral monocytes, was enhanced in TTBK1 and TTBK1/JNPL3 but not in other groups in the spinal cord. Furthermore, primary cultured mouse motor neurons showed axonal degeneration after transient expression of the TTBK1 gene or treatment with conditioned media derived from lipopolysaccharide-stimulated microglia; this was partially blocked by silencing of the endogenous TTBK1 gene in neurons. These data suggest that TTBK1 accelerates motor neuron neurodegeneration by recruiting proinflammatory monocytes and enhancing sensitivity to neurotoxicity in inflammatory conditions.
Assuntos
Demência Frontotemporal/genética , Degeneração Neural/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas tau/genética , Animais , Modelos Animais de Doenças , Demência Frontotemporal/metabolismo , Demência Frontotemporal/patologia , Camundongos , Camundongos Transgênicos , Mutação , Degeneração Neural/metabolismo , Degeneração Neural/patologia , Neurônios/metabolismo , Neurônios/patologia , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Medula Espinal/patologia , Tauopatias/genética , Tauopatias/metabolismo , Tauopatias/patologia , Proteínas tau/metabolismoRESUMO
OBJECTIVE: Much of the genetic basis for Alzheimer disease (AD) is unexplained. We sought to identify novel AD loci using a unique family-based approach that can detect robust associations with infrequent variants (minor allele frequency < 0.10). METHODS: We conducted a genome-wide association study in the Framingham Heart Study (discovery) and NIA-LOAD (National Institute on Aging-Late-Onset Alzheimer Disease) Study (replication) family-based cohorts using an approach that accounts for family structure and calculates a risk score for AD as the outcome. Links between the most promising gene candidate and AD pathogenesis were explored in silico as well as experimentally in cell-based models and in human brain. RESULTS: Genome-wide significant association was identified with a PLXNA4 single nucleotide polymorphism (rs277470) located in a region encoding the semaphorin-3A (SEMA3A) binding domain (meta-analysis p value [meta-P] = 4.1 × 10(-8) ). A test for association with the entire region was also significant (meta-P = 3.2 × 10(-4) ). Transfection of SH-SY5Y cells or primary rat neurons with full-length PLXNA4 (TS1) increased tau phosphorylation with stimulated by SEMA3A. The opposite effect was observed when cells were transfected with shorter isoforms (TS2 and TS3). However, transfection of any isoform into HEK293 cells stably expressing amyloid ß (Aß) precursor protein (APP) did not result in differential effects on APP processing or Aß production. Late stage AD cases (n = 9) compared to controls (n = 5) had 1.9-fold increased expression of TS1 in cortical brain tissue (p = 1.6 × 10(-4) ). Expression of TS1 was significantly correlated with the Clinical Dementia Rating score (ρ = 0.75, p = 2.2 × 10(-4) ), plaque density (ρ = 0.56, p = 0.01), and Braak stage (ρ = 0.54, p = 0.02). INTERPRETATION: Our results indicate that PLXNA4 has a role in AD pathogenesis through isoform-specific effects on tau phosphorylation.
Assuntos
Doença de Alzheimer/genética , Lobo Frontal/metabolismo , Receptores de Superfície Celular/metabolismo , Proteínas tau/metabolismo , Idoso , Idoso de 80 Anos ou mais , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Estudos de Coortes , Feminino , Lobo Frontal/patologia , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Células HEK293 , Hipocampo/citologia , Hipocampo/metabolismo , Humanos , Masculino , Linhagem , Fosforilação/genética , Fosforilação/fisiologia , Polimorfismo de Nucleotídeo Único/genética , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Ratos , Receptores de Superfície Celular/genéticaRESUMO
Spinocerebellar ataxia type 14 (SCA14) is an autosomal dominant disease caused by mutations in the gene encoding protein kinase C gamma (PKC gamma). We report an SCA14 family with a novel deletion of a termination-codon-containing region, resulting in a missense change and a C-terminal 13-amino-acid extension with increased kinase activity. Notably, one patient with a severe phenotype is the first homozygote for the mutation causing SCA14. We show the novel molecular consequences of increased kinase activities of mutants: aprataxin (APTX), a DNA repair protein causative for autosomal recessive ataxia, was found to be a preferential substrate of mutant PKC gamma, and phosphorylation inhibited its nuclear entry. The phosphorylated residue was Thr111, located adjacent to the nuclear localization signal, and disturbed interactions with importin alpha, a nuclear import adaptor. Decreased nuclear APTX increased oxidative stress-induced DNA damage and cell death. Phosphorylation-resistant APTX, kinase inhibitors, and antioxidants may be therapeutic options for SCA14.
Assuntos
Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/metabolismo , Regulação para Baixo , Proteínas Nucleares/metabolismo , Proteína Quinase C/metabolismo , Ataxias Espinocerebelares/metabolismo , Transporte Ativo do Núcleo Celular , Idoso de 80 Anos ou mais , Sequência de Aminoácidos , Sequência de Bases , Linhagem Celular , Núcleo Celular/química , Núcleo Celular/genética , Dano ao DNA , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Proteínas Nucleares/química , Proteínas Nucleares/genética , Linhagem , Fosforilação , Proteína Quinase C/química , Proteína Quinase C/genética , Transporte Proteico , Ataxias Espinocerebelares/genética , Adulto JovemRESUMO
Intranuclear events due to mutations in the Parkin gene remain elusive in autosomal recessive juvenile parkinsonism (ARJP). We identified a mutant PARKIN protein in fibroblast cultures from a pair of siblings with ARJP who were homozygous for the exon 4-deleted Parkin gene. Disease was mild in one patient and debilitating in the other. The detected mutant, encoded by a transcript lacking exon 3 as well as exon 4, is an in-frame deletion that removes 121 aa, resulting in a 344-aa protein (PaDel3,4). Cell culture and transfection studies revealed negative correlations between expression levels of PaDel3,4 and those of cell cycle proteins, including cyclin E, CDK2, ppRb, and E2F-1, and demonstrated that GFP-PaDel3,4 entered nucleus and ubiquitinated cyclin E as a part of SCF(hSel-10) ligase complex in the patient cells. In addition, nuclear localization signal-tagged PaDel3,4 expressed in the transfected patient cells most effectively ubiquitinated cyclin E and reduced DNA damage, protecting cells from oxidative stress. Antisense-oligonucleotide treatment promoted skipping of exon 3 and thus generated PaDel3,4, increasing cell survival. Collectively, we propose that naturally- and experimentally-induced exon skipping at least partly restores the mutant Parkin gene deficit, providing a molecular basis for the development of therapeutic exon skipping.
Assuntos
Éxons/genética , Fibroblastos/metabolismo , Transtornos Parkinsonianos/genética , Ubiquitina-Proteína Ligases/genética , Idoso , Butionina Sulfoximina/farmacologia , Sobrevivência Celular , Células Cultivadas , Ciclina E/metabolismo , Dano ao DNA/genética , Feminino , Fibroblastos/efeitos dos fármacos , Deleção de Genes , Humanos , Masculino , Oligonucleotídeos Antissenso/genética , Fases de Leitura Aberta/genética , Estresse Oxidativo/genética , Proteínas Ligases SKP Culina F-Box , TransfecçãoRESUMO
Triple A syndrome is an autosomal recessive neurological disease, mimicking motor neuron disease, and is caused by mutant ALADIN, a nuclear-pore complex component. We recently discovered that the pathogenesis involved impaired nuclear import of DNA repair proteins, including DNA ligase I and the cerebellar ataxia causative protein aprataxin. Such impairment was overcome by fusing classical nuclear localization signal (NLS) and 137-aa downstream sequence of XRCC1, designated stretched NLS (stNLS). We report here that the minimum essential sequence of stNLS (mstNLS) is residues 239-276, downsized by more than 100 aa. mstNLS enabled efficient nuclear import of DNA repair proteins in patient fibroblasts, functioned under oxidative stress, and reduced oxidative-stress-induced cell death, more effectively than stNLS. The stress-tolerability of mstNLS was also exerted in control fibroblasts and neuroblastoma cells. These findings may help develop treatments for currently intractable triple A syndrome and other oxidative-stress-related neurological diseases, and contribute to nuclear compartmentalization study.
Assuntos
Insuficiência Adrenal/metabolismo , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/metabolismo , Síndromes do Olho Seco/metabolismo , Acalasia Esofágica/metabolismo , Sinais de Localização Nuclear , Transporte Ativo do Núcleo Celular/genética , Insuficiência Adrenal/terapia , Sequência de Aminoácidos , Células Cultivadas , DNA Ligase Dependente de ATP , DNA Ligases/genética , DNA Ligases/metabolismo , Proteínas de Ligação a DNA/genética , Síndromes do Olho Seco/terapia , Acalasia Esofágica/terapia , Fibroblastos/metabolismo , Humanos , Dados de Sequência Molecular , Sinais de Localização Nuclear/genética , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Estresse Oxidativo , Síndrome , Proteína 1 Complementadora Cruzada de Reparo de Raio-XRESUMO
Odor is the only sensation thought to be unrelated to the thalamus. However, accumulating evidence suggests that the dorsomedial nucleus (DM) of the thalamus is associated with odor. Although the thalamus is prone to ischemia, only a single patient with bilateral DM infarctions was reported to have odor abnormalities. We describe a second such patient with infarctions involving the left DM and the right ventral posterior nucleus and ventral lateral nucleus, nuclei adjacent to the DM, associated with transient edema. In contrast to the previous case, our patient had transient odor abnormality. These observations suggested that direct and/or indirect bilateral involvement of the DM might be associated with odor abnormalities in patients with thalamic infarction.
Assuntos
Infarto Encefálico/complicações , Transtornos do Olfato/etiologia , Condutos Olfatórios/fisiopatologia , Distúrbios do Paladar/etiologia , Tálamo/irrigação sanguínea , Idoso , Infarto Encefálico/diagnóstico , Infarto Encefálico/patologia , Lateralidade Funcional , Humanos , Imageamento por Ressonância Magnética , Masculino , Transtornos do Olfato/patologia , Condutos Olfatórios/patologia , Distúrbios do Paladar/patologia , Tálamo/patologiaRESUMO
Early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH)/ataxia with oculomotor apraxia type 1 (AOA1) is caused by mutations in the gene encoding aprataxin (APTX). Although several in vitro findings proposed that impaired enzymatic activities of APTX are responsible for EAOH/AOA1, potential instability of mutant proteins has also been suggested as the pathogenesis based on in vivo finding that mutant proteins are almost undetectable in EAOH/AOA1 tissues or cells. The present study aimed to experimentally prove instability of mutant proteins in neuronal cells, the cell type preferentially affected by this disease. Results of pulse-chase experiments demonstrated that all of the disease-associated mutants had extremely shorter half-lives than the WT. We further found that mutants were targeted for rapid proteasome-mediated degradation. These results help establish pathogenic and physiological protein characteristics of APTX in neuronal cells.
Assuntos
Encéfalo/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Neurônios/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/metabolismo , Degenerações Espinocerebelares/metabolismo , Biomarcadores/análise , Biomarcadores/metabolismo , Encéfalo/fisiopatologia , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Estabilidade Enzimática/genética , Predisposição Genética para Doença/genética , Meia-Vida , Humanos , Mutação/genética , Proteínas Nucleares/genética , Complexo de Endopeptidases do Proteassoma/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Degenerações Espinocerebelares/genética , Degenerações Espinocerebelares/fisiopatologia , Fatores de TempoRESUMO
BACKGROUND: ALS exclusively involves motor neurons, however, accumulating evidence suggests involvement of sympathetic neurons, as in other diseases including Parkinson's disease and multiple system atrophy. In these diseases increased risk of sudden cardiac arrest is established, while that in ALS remains uncertain. METHODS: The authors retrospectively studied 12 pathologically confirmed sporadic ALS patients who received no assisted ventilation. Among them, two patients died of sudden cardiac arrest. Changes in QTc interval and dispersion, indices of sympathetic activities obtainable by routine electrocardiograms, were evaluated at the early stage and the terminal stage. Pathologically, intermediolateral nucleus (IML) sympathetic neurons in the upper thoracic cord were examined. RESULTS: The QTc intervals and dispersion were significantly increased at the terminal stage compared with that at the early stage (p<0.01). The numbers of IML neurons were significantly lower in ALS patients than in controls (p=0.017), and had linear inverse correlation with the rate of increases in maximum QTc interval and QTc dispersion (p=0.01, r=-0.915 and p=0.02, r=-0.884). Notably, two patients with sudden cardiac arrest showed longer QTc interval, larger QTc dispersion, and lower number of IML neurons than most of others. CONCLUSIONS: Patients with ALS had reduced sympathetic activities at the terminal stage of disease, presumably due to neuronal loss in IML, which may increase risk of sudden cardiac arrest. Thus, prolonged QTc intervals and increased QTc dispersion may suggest an increased risk of sudden death in ALS, as in other neurodegenerative diseases.
Assuntos
Esclerose Lateral Amiotrófica/complicações , Doenças do Sistema Nervoso Autônomo/etiologia , Doenças do Sistema Nervoso Autônomo/fisiopatologia , Morte Súbita Cardíaca/etiologia , Coração/fisiopatologia , Sistema Nervoso Simpático/fisiopatologia , Idoso , Esclerose Lateral Amiotrófica/fisiopatologia , Doenças do Sistema Nervoso Autônomo/patologia , Eletrocardiografia , Feminino , Coração/inervação , Humanos , Síndrome do QT Longo/etiologia , Síndrome do QT Longo/fisiopatologia , Masculino , Pessoa de Meia-Idade , Degeneração Neural/etiologia , Degeneração Neural/patologia , Degeneração Neural/fisiopatologia , Neurônios/patologia , Estudos Retrospectivos , Fatores de Risco , Medula Espinal/patologia , Medula Espinal/fisiopatologia , Sistema Nervoso Simpático/patologiaRESUMO
We describe the findings on single photon emission computed tomography (SPECT) in a patient who had genetically definite megalencephalic leukoencephalopathy with subcortical cysts. Technetium-99m-ethyl cysteinate dimer SPECT revealed hypoperfusion in the cerebral white matter, which had shown high signal intensity on magnetic resonance imaging (MRI) T2 images. Hypoperfusion was also unexpectedly found in the frontal cortices, which showed no abnormalities on MRI. This frontal abnormality corresponded clinically to a low score on the frontal assessment battery. Decreased GABA receptor density as suggested by (123)I-Iomazenil SPECT provided further evidence of cortical neuron dysfunction. Although confirmation must await future larger-scale SPECT and functional studies, our findings suggest that SPECT can be used to non-invasively monitor in vivo cortical function in this disease.
Assuntos
Cistos do Sistema Nervoso Central/diagnóstico por imagem , Cefalometria , Córtex Cerebral/diagnóstico por imagem , Demência Vascular/diagnóstico por imagem , Proteínas de Membrana/genética , Tomografia Computadorizada de Emissão de Fóton Único , Adulto , Astrócitos/metabolismo , Cistos do Sistema Nervoso Central/genética , Cerebelo/irrigação sanguínea , Cerebelo/diagnóstico por imagem , Córtex Cerebral/irrigação sanguínea , Aberrações Cromossômicas , Códon , Consanguinidade , Cisteína/análogos & derivados , Análise Mutacional de DNA , Demência Vascular/genética , Genes Recessivos , Homozigoto , Humanos , Leucina/genética , Imageamento por Ressonância Magnética , Masculino , Exame Neurológico , Compostos de Organotecnécio , Serina/genéticaRESUMO
Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurological disorder caused by a CAG repeat expansion in the DRPLA gene encoding polyglutamine (polyQ). Although previous experimental studies have demonstrated that histone deacetylase (HDAC) inhibitors are therapeutically active, known HDAC inhibitors have considerable adverse effects clinically. To identify new HDAC inhibitors for the treatment of DRPLA, we evaluated a new series of HDAC inhibitors, N-hydroxycarboxamides, with our drug screening system, which uses neuronal PC12 cells stably transfected with a part of the DRPLA gene. We found that two of four N-hydroxycarboxamides significantly reduced polyQ-induced cell death. The essential structure of these compounds is a hydroxamic acid residue, which is shared with trichostatin A, a known HDAC inhibitor. Although our study showed mild neuroprotective effects, further structural modification of compounds that retain this residue may decrease cytotoxicity and increase protective activity against polyQ toxicity.
Assuntos
Cantaridina/análogos & derivados , Inibidores de Histona Desacetilases , Fármacos Neuroprotetores/farmacologia , Peptídeos/antagonistas & inibidores , Animais , Cantaridina/química , Cantaridina/farmacologia , Contagem de Células/métodos , Morte Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Interações Medicamentosas , Histona Desacetilases/química , Proteínas do Tecido Nervoso/genética , Células PC12 , Peptídeos/toxicidade , Ratos , Transfecção/métodosRESUMO
The etiology of idiopathic Parkinson's disease (idPD) remains enigmatic despite recent successes in identification of genes (PARKs) that underlie familial PD. To find new keys to this incurable neurodegenerative disorder we focused on the poorly understood PARK14 disease locus (Pla2g6 gene) and the store-operated Ca(2+) signalling pathway. Analysis of the cells from idPD patients reveals a significant deficiency in store-operated PLA2g6-dependent Ca(2+) signalling, which we can mimic in a novel B6.Cg-Pla2g6(ΔEx2-VB) (PLA2g6 ex2(KO)) mouse model. Here we demonstrate that genetic or molecular impairment of PLA2g6-dependent Ca(2+) signalling is a trigger for autophagic dysfunction, progressive loss of dopaminergic (DA) neurons in substantia nigra pars compacta and age-dependent L-DOPA-sensitive motor dysfunction. Discovery of this previously unknown sequence of pathological events, its association with idPD and our ability to mimic this pathology in a novel genetic mouse model opens new opportunities for finding a cure for this devastating neurodegenerative disease.
Assuntos
Encéfalo/metabolismo , Sinalização do Cálcio/genética , Neurônios Dopaminérgicos/metabolismo , Fosfolipases A2 do Grupo VI/genética , Movimento , Doença de Parkinson/genética , Idoso , Animais , Western Blotting , Encéfalo/patologia , Neurônios Dopaminérgicos/patologia , Fibroblastos/metabolismo , Fibroblastos/patologia , Fosfolipases A2 do Grupo VI/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas , Camundongos , Camundongos Transgênicos , Microscopia Confocal , Microscopia de Fluorescência , Pessoa de Meia-Idade , Destreza Motora , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Pele/citologia , Adulto JovemRESUMO
We investigated the clinical efficacy and tolerability of 45 mg/day mosapride, a selective 5-hydroxytryptamine type 4 (5-HT4) agonist, in an open-label study involving five patients with Parkinson's disease (PD) who had response fluctuations (RFs). 'On' time and motor function scores were determined, and gastric motility was measured by a radionuclide gastric emptying (GE) test, the most reliable quantitative method available. We found that mosapride therapy significantly shortened GE half-time, reduced RFs, and improved motor functions in all patients. There were no adverse reactions. We conclude that selective 5-HT4 agonist therapy is beneficial for patients with PD who have RFs.
Assuntos
Benzamidas/uso terapêutico , Motilidade Gastrointestinal/fisiologia , Morfolinas/uso terapêutico , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/fisiopatologia , Receptores 5-HT4 de Serotonina/efeitos dos fármacos , Agonistas do Receptor de Serotonina/uso terapêutico , Idoso , Antiparkinsonianos/sangue , Antiparkinsonianos/farmacocinética , Benzamidas/efeitos adversos , Feminino , Esvaziamento Gástrico/efeitos dos fármacos , Humanos , Levodopa/sangue , Levodopa/farmacocinética , Morfolinas/efeitos adversos , Doença de Parkinson/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Estômago/diagnóstico por imagemRESUMO
Accumulation of pathological tau protein is a major hallmark of Alzheimer's disease. Tau protein spreads from the entorhinal cortex to the hippocampal region early in the disease. Microglia, the primary phagocytes in the brain, are positively correlated with tau pathology, but their involvement in tau propagation is unknown. We developed an adeno-associated virus-based model exhibiting rapid tau propagation from the entorhinal cortex to the dentate gyrus in 4 weeks. We found that depleting microglia dramatically suppressed the propagation of tau and reduced excitability in the dentate gyrus in this mouse model. Moreover, we demonstrate that microglia spread tau via exosome secretion, and inhibiting exosome synthesis significantly reduced tau propagation in vitro and in vivo. These data suggest that microglia and exosomes contribute to the progression of tauopathy and that the exosome secretion pathway may be a therapeutic target.
Assuntos
Exossomos/metabolismo , Hipocampo/metabolismo , Microglia/metabolismo , Neurônios/metabolismo , Proteínas tau/metabolismo , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Animais , Modelos Animais de Doenças , Córtex Entorrinal/patologia , Hipocampo/patologia , Masculino , Camundongos TransgênicosRESUMO
A 50-year-old man who first noticed shaking of the hands at age of 18 and had previous history of three convulsive episodes was admitted to our department because of the generalized tonic seizure with loss of consciousness. Family history showed that 7 members had similar shaking and one had generalized seizure. On neurological examination, rhythmic myoclonic jerks were noted in the bilateral upper limbs, and was remarkably more severe on the left. Other neurological findings were normal. Based on the benign clinical course, familial history, and the normal range of pyruvate and lactate levels in serum and cerebrospinal fluid, we diagnosed familial essential myoclonus and epilepsy (FEME)/benign adult familial myoclonic and epilepsy (BAFME). After admission, we performed electrophysiological test. EEG showed spike discharge mainly in the left parietooccipital lobe. Jerk-locked back averaging (JLA) showed spikes 30 msec precedings the trigger in the left parietooccipital lobe. Because JLA spikes are commonly found 20 msec precedings the trigger, we consider the subtraction time of 10 msec was due to the conduction through the corpus callosum. Some reports showed that in progressive myoclonus epilepsy patients, transcallosal excitation of one hemisphere by the other was critical for generalized seizure. In cases of FEME/BAFME, epileptic focus in the hemisphere ipsilateral to the myoclonus limbs has not previously reported. Our case suggested that generalization of the seizure was caused by the interhemispheric excitation through the corpus callosum.
Assuntos
Eletroencefalografia , Epilepsias Mioclônicas/genética , Epilepsias Mioclônicas/fisiopatologia , Eletromiografia , Epilepsia Generalizada/fisiopatologia , Potenciais Somatossensoriais Evocados , Humanos , Masculino , Pessoa de Meia-Idade , LinhagemAssuntos
Ataxia Cerebelar/complicações , Doenças do Sistema Nervoso Periférico/etiologia , Idoso de 80 Anos ou mais , Ataxia Cerebelar/genética , Cromossomos Humanos Par 16/genética , Feminino , Fatores de Troca do Nucleotídeo Guanina/genética , Humanos , Hipotensão Ortostática/etiologia , Masculino , Pessoa de Meia-Idade , Espectrina/genéticaRESUMO
Bardet-Biedl syndrome (BBS) is an autosomal recessive disorder characterized by rod-cone dystrophy, polydactyly, central obesity, mental retardation, and hypogonadism. Although many organs are involved in BBS, hyperammonemia caused by portal hypertension has been reported previously in only a single patient. We describe the second such patient with BBS and hyperammonemia, associated with fluctuating mental impairment. The patient was a 17-year-old boy with BBS. Esophageal, gastric, and rectal varices and mild hepatic dysfunction started to develop at 5 years of age. A liver biopsy showed dilated portal veins with mild fibrosis in portal tract. From the age of 17 years, he often had forced laughter with apparently normal consciousness. Laboratory examinations revealed hyperammonemia (112.2mg/ml). Oral medication lowered the blood ammonia level to 69.9 mg/ml, reduced the frequency of forced laughter, and improved his IQ. Patients with BBS may have additional diseases or conditions that affect mental status, such as hyperammonemia. Physicians should explore the underlying causes of these conditions and treat such patients, who already have a compromised quality of life.
Assuntos
Síndrome de Bardet-Biedl/complicações , Hiperamonemia/complicações , Deficiência Intelectual/fisiopatologia , Adolescente , Humanos , Deficiência Intelectual/tratamento farmacológico , Deficiência Intelectual/etiologia , Riso/fisiologia , Riso/psicologia , Masculino , Resultado do TratamentoRESUMO
OBJECTIVES: Sleep attacks (SAs) in Parkinson's disease (PD) are rare, but clinically important because they significantly impair the daily lives of patients. Causes of SAs include long-term activation of dopaminergic (especially D3) receptors. Recent studies suggest that SAs in PD may be related to impairment of hypothalamic orexin neurons, similar to narcolepsy. Whether orexin is associated with long-term activation of dopaminergic receptors remains uncertain. PATIENTS AND METHODS: We measured levels of orexin in samples of spinal cerebrospinal fluid (CSF) from 25 patients with PD, including 9 with excessive daytime sleepiness and 4 with SAs. Furthermore, in the four patients with SAs, the selective dopamine D1/D2 agonist pergolide was substituted for the causative drugs with D3 stimulatory activity, and CSF-orexin levels were measured before and after switching treatment. RESULTS: In the 25 patients with PD, including the 4 patients with SAs, lower CSF-orexin levels were associated with a longer disease duration, which has been linked to a higher incidence of SAs. Switching treatment to pergolide significantly increased CSF-orexin levels and completely resolved SAs in the four patients with PD. CONCLUSION: Despite the small number of patients studied, our results suggest that orexin transmission is most likely involved in SAs in PD and that abrogation of D3 receptor stimulation may increase orexin and thereby inhibit SAs.
Assuntos
Agonistas de Dopamina/farmacologia , Peptídeos e Proteínas de Sinalização Intracelular/líquido cefalorraquidiano , Neuropeptídeos/líquido cefalorraquidiano , Doença de Parkinson/líquido cefalorraquidiano , Pergolida/farmacologia , Transtornos do Sono-Vigília/líquido cefalorraquidiano , Transtornos do Sono-Vigília/etiologia , Adulto , Idoso , Feminino , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Masculino , Pessoa de Meia-Idade , Neuropeptídeos/metabolismo , Orexinas , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/fisiopatologia , Pergolida/administração & dosagem , Radioimunoensaio , Receptores de Dopamina D1/agonistas , Receptores de Dopamina D2/agonistas , Receptores de Dopamina D3/metabolismo , Índice de Gravidade de Doença , Transtornos do Sono-Vigília/metabolismoRESUMO
OBJECTIVE: Early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH)/ataxia with oculomotor apraxia type 1 (AOA1) is an autosomal recessive form of cerebellar ataxia. The causative protein for EAOH/AOA1, aprataxin (APTX), interacts with X-ray repair cross-complementing 1 (XRCC1), a scaffold DNA repair protein for single-strand breaks (SSBs). The goal of this study was to prove the functional involvement of APTX in SSB repair (SSBR). METHODS: We visualized the SSBR process with a recently developed laser irradiation system that allows real-time observation of SSBR proteins and with a local ultraviolet-irradiation system using a XPA-UVDE cell line that repairs DNA lesions exclusively via SSBR. APTX was knocked down using small interference RNA in the cells. Oxidative stress-induced DNA damage and cell death were assessed in EAOH fibroblasts and cerebellum. RESULTS: Our systems showed the XRCC1-dependent recruitment of APTX to SSBs. SSBR was impaired in APTX-knocked-down cells. Oxidative stress in EAOH fibroblasts readily induced SSBs and cell death, which were blocked by antioxidants. Accumulated oxidative DNA damage was confirmed in EAOH cerebellum. INTERPRETATION: This study provides the first direct evidence for the functional involvement of APTX in SSBR and in vivo DNA damage in EAOH/AOA1, and suggests a benefit of antioxidant treatment.