RESUMO
Alzheimer's disease (AD) is a neurodegenerative disease that impairs multiple memory domains without an effective prevention or treatment approach. Amyloid plaque-induced neuroinflammation exacerbates neurodegeneration and cognitive impairment in AD. To reduce neuroinflammation, we applied prebiotics or synbiotics to modulate the gut-brain axis in the AD mouse model. AD-like deficits were reduced in mice treated with synbiotics, suggesting that dietary modulation of the gut-brain axis is a potential approach to delay AD progression.
Assuntos
Doença de Alzheimer , Doenças Neurodegenerativas , Simbióticos , Animais , Modelos Animais de Doenças , Inflamação , Camundongos , Camundongos TransgênicosRESUMO
BACKGROUND: Changes in cerebrospinal fluid, neuroimaging, and cognitive functions have been used as diagnostic biomarkers of Alzheimer's disease (AD). This study aimed to investigate the temporal trajectories of plasma biomarkers in subjects with mild cognitive impairment (MCI) and patients with AD relative to healthy controls (HCs). METHODS: In this longitudinal study, 82 participants (31 HCs, 33 MCI patients, and 18 AD patients) were enrolled. After 3 years, 7 HCs had transitioned to MCI and 10 subjects with MCI had converted to AD. We analyzed plasma amyloid beta (Aß) and tau proteins at baseline and annually to correlate with biochemical data and neuropsychological scores. RESULTS: Longitudinal data analysis showed an evolution of Aß-related biomarkers over time within patients, whereas tau-related biomarkers differed primarily across diagnostic classifications. An initial steady increase in Aß42 in the MCI stage was followed by a decrease just prior to clinical AD onset. Hyperphosphorylated tau protein levels correlated with cognitive decline in the MCI stage, but not in the AD stage. CONCLUSION: Plasma Aß and tau levels change in a dynamic, nonlinear, nonparallel manner over the AD continuum. Changes in plasma Aß concentration are time-dependent, whereas changes in hyperphosphorylated tau protein levels paralleled the clinical progression of MCI. It remains to be clarified whether diagnostic efficiency can be improved by combining multiple plasma markers or combining plasma markers with other diagnostic biomarkers.
Assuntos
Doença de Alzheimer/sangue , Precursor de Proteína beta-Amiloide/sangue , Disfunção Cognitiva/sangue , Proteínas tau/sangue , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/genética , Doença de Alzheimer/psicologia , Precursor de Proteína beta-Amiloide/genética , Apolipoproteínas E/genética , Biomarcadores/sangue , Disfunção Cognitiva/genética , Disfunção Cognitiva/psicologia , Feminino , Genótipo , Humanos , Estudos Longitudinais , Masculino , Testes Neuropsicológicos , Fosforilação , Proteínas tau/genéticaRESUMO
Acid-sensing ion channel-1a (ASIC1a) is localized in brain regions with high synaptic density and is thought to contribute to synaptic plasticity, learning, and memory. A prominent hypothesis is that activation of postsynaptic ASICs promotes depolarization, thereby augmenting N-methyl-d-aspartate receptor function and contributing to the induction of long-term potentiation (LTP). However, evidence for activation of postsynaptic ASICs during neurotransmission has not been established. Here, we re-examined the role of ASIC1a in LTP in the hippocampus using pharmacological and genetic approaches. Our results showed that a tarantula peptide psalmotoxin, which profoundly blocked ASIC currents in the hippocampal neurons, had no effect on LTP. Similarly, normal LTP was robustly generated in ASIC1a-null mice. A further behavioral analysis showed that mice lacking ASIC1a had normal performance in hippocampus-dependent spatial memory. In summary, our results indicate that ASIC1a is not required for hippocampal LTP and spatial memory. We therefore propose that the role of ASIC1a in LTP and spatial learning should be reassessed.
Assuntos
Bloqueadores do Canal Iônico Sensível a Ácido/farmacologia , Canais Iônicos Sensíveis a Ácido/metabolismo , Hipocampo/fisiologia , Potenciação de Longa Duração/fisiologia , Aprendizagem em Labirinto/fisiologia , Canais Iônicos Sensíveis a Ácido/genética , Animais , Feminino , Hipocampo/efeitos dos fármacos , Potenciação de Longa Duração/efeitos dos fármacos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Camundongos , Camundongos Knockout , Plasticidade Neuronal/efeitos dos fármacos , Plasticidade Neuronal/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
The deposition of amyloid-ß (Aß) peptide, which is generated from amyloid precursor protein (APP), is the pathological hallmark of Alzheimer's disease (AD). Three APP familial AD mutations (D678H, D678N, and H677R) located at the sixth and seventh amino acid of Aß have distinct effect on Aß aggregation, but their influence on the physiological and pathological roles of APP remain unclear. We found that the D678H mutation strongly enhances amyloidogenic cleavage of APP, thus increasing the production of Aß. This enhancement of amyloidogenic cleavage is likely because of the acceleration of APPD678H sorting into the endosomal-lysosomal pathway. In contrast, the APPD678N and APPH677R mutants do not cause the same effects. Therefore, this study indicates a regulatory role of D678H in APP sorting and processing, and provides genetic evidence for the importance of APP sorting in AD pathogenesis. The internalization of amyloid precursor protein (APP) increases its opportunity to be processed by ß-secretase and to produce Amyloid-ß (Aß) that causes Alzheimer's disease (AD). We report a pathogenic APPD678H mutant that enhances APP internalization into the endosomal-lysosomal pathway and thus promotes the ß-secretase cleavage and Aß production. This study provides genetic evidence for the importance of APP sorting in AD pathogenesis.
Assuntos
Doença de Alzheimer/genética , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Mutação/genética , Cloreto de Amônio/farmacologia , Biotinilação , Células HEK293 , Humanos , Lisossomos/efeitos dos fármacos , Lisossomos/genética , Lisossomos/metabolismo , Fragmentos de Peptídeos/metabolismo , Transporte Proteico/efeitos dos fármacos , Transporte Proteico/genética , TransfecçãoRESUMO
Abnormally high concentrations of Zn(2+), Cu(2+), and Fe(3+) are present along with amyloid-ß (Aß) in the senile plaques in Alzheimer disease, where Al(3+) is also detected. Aß aggregation is the key pathogenic event in Alzheimer disease, where Aß oligomers are the major culprits. The fundamental mechanism of these metal ions on Aß remains elusive. Here, we employ 4,4'-Bis(1-anilinonaphthalene 8-sulfonate) and tyrosine fluorescence, CD, stopped flow fluorescence, guanidine hydrochloride denaturation, and photo-induced cross-linking to elucidate the effect of Zn(2+), Cu(2+), Fe(3+), and Al(3+) on Aß at the early stage of the aggregation. Furthermore, thioflavin T assay, dot blotting, and transmission electron microscopy are utilized to examine Aß aggregation. Our results show that Al(3+) and Zn(2+), but not Cu(2+) and Fe(3+), induce larger hydrophobic exposures of Aß conformation, resulting in its significant destabilization at the early stage. The metal ion binding induces Aß conformational changes with micromolar binding affinities and millisecond binding kinetics. Cu(2+) and Zn(2+) induce similar assembly of transiently appearing Aß oligomers at the early state. During the aggregation, we found that Zn(2+) exclusively promotes the annular protofibril formation without undergoing a nucleation process, whereas Cu(2+) and Fe(3+) inhibit fibril formation by prolonging the nucleation phases. Al(3+) also inhibits fibril formation; however, the annular oligomers co-exist in the aggregation pathway. In conclusion, Zn(2+), Cu(2+), Fe(3+), and Al(3+) adopt distinct folding and aggregation mechanisms to affect Aß, where Aß destabilization promotes annular protofibril formation. Our study facilitates the understanding of annular Aß oligomer formation upon metal ion binding.
Assuntos
Alumínio/química , Precursor de Proteína beta-Amiloide/química , Amiloide/química , Cobre/química , Ferro/química , Zinco/química , Amiloide/ultraestrutura , Humanos , Multimerização Proteica , Estabilidade ProteicaRESUMO
The Arctic mutation within the amyloid-beta (Abeta) peptide causes Alzheimer disease. In vitro, Arctic-mutant Abeta forms (proto)fibrils more effectively than wild-type Abeta. We generated transgenic mouse lines expressing Arctic-mutant human amyloid precursor proteins (hAPP). Amyloid plaques formed faster and were more extensive in Arctic mice than in hAPP mice expressing wild-type Abeta, even though Arctic mice had lower Abeta(1-42/1-40) ratios. Thus, the Arctic mutation is highly amyloidogenic in vivo.
Assuntos
Doença de Alzheimer/genética , Precursor de Proteína beta-Amiloide/metabolismo , Hipocampo/metabolismo , Mutação/genética , Placa Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animais , Western Blotting , Ensaio de Imunoadsorção Enzimática , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos TransgênicosRESUMO
The accumulation of amyloid-beta (Abeta) peptides in the brain of patients with Alzheimer's disease (AD) may arise from an imbalance between Abeta production and clearance. Overexpression of the Abeta-degrading enzyme neprilysin in brains of human amyloid precursor protein (hAPP) transgenic mice decreases overall Abeta levels and amyloid plaque burdens. Because AD-related synaptic and cognitive deficits appear to be more closely related to Abeta oligomers than to plaques, it is important to determine whether increased neprilysin activity also diminishes the levels of pathogenic Abeta oligomers and related neuronal deficits in vivo. To address this question, we crossed hAPP transgenic mice with neprilysin transgenic mice and analyzed their offspring. Neprilysin overexpression reduced soluble Abeta levels by 50% and effectively prevented early Abeta deposition in the neocortex and hippocampus. However, it did not reduce levels of Abeta trimers and Abeta*56 or improve deficits in spatial learning and memory. The differential effect of neprilysin on plaques and oligomers suggests that neprilysin-dependent degradation of Abeta affects plaques more than oligomers and that these structures may form through distinct assembly mechanisms. Neprilysin's inability to prevent learning and memory deficits in hAPP mice may be related to its inability to reduce pathogenic Abeta oligomers. Reduction of Abeta oligomers will likely be required for anti-Abeta treatments to improve cognitive functions.
Assuntos
Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Transtornos Cognitivos/genética , Neprilisina/metabolismo , Placa Amiloide/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/fisiopatologia , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Encéfalo/patologia , Encéfalo/fisiopatologia , Modelos Animais de Doenças , Regulação para Baixo/genética , Regulação da Expressão Gênica/genética , Humanos , Deficiências da Aprendizagem/genética , Deficiências da Aprendizagem/metabolismo , Deficiências da Aprendizagem/fisiopatologia , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neprilisina/genética , Polímeros/metabolismoRESUMO
Utilizing the N-methyl-d-aspartate (NMDA) receptor antagonist as a strategy, memantine is the only agent available for clinically treating mild to severe Alzheimer's disease (AD). Our aim was to develop novel similar herb-based drugs. Using a screening platform, ginkgolide A (GA), a pure compound extracted from Ginkgo biloba, was found to attenuate amyloid ß (Aß)-induced abnormal depolarization in mouse primary cortical neurons. Using receptor agonists, it was determined that GA inhibits both NMDA receptors and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. Furthermore, the Aß-induced increase in c-Jun N-terminal kinase phosphorylation in neurons was prevented by GA. Body weight, glutamate oxaloacetate transaminase, glutamic-pyruvic transaminase, liver histology, and kidney histology were similar when the wild-type/AD animal model mice with and without GA treatment were compared. This pure compound improves the memory of wild-type mice. Our findings indicate that GA has great potential clinically for the treatment of AD because it might target NMDA receptors just like memantine.
Assuntos
Doença de Alzheimer/prevenção & controle , Peptídeos beta-Amiloides/toxicidade , Córtex Cerebral/efeitos dos fármacos , Ginkgo biloba/química , Ginkgolídeos/administração & dosagem , Lactonas/administração & dosagem , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/administração & dosagem , Extratos Vegetais/administração & dosagem , Doença de Alzheimer/etiologia , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Córtex Cerebral/citologia , Córtex Cerebral/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/citologia , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismoRESUMO
Levels of amyloid-ß (Aß) and tau peptides in brain have been associated with Alzheimer disease (AD). The current study investigated the abilities of plasma Aß42 and total-tau (t-tau) levels in predicting cognitive decline in subjects with amnestic mild cognitive impairment (MCI). Plasma Aß42 and t-tau levels were quantified in 22 participants with amnestic MCI through immunomagnetic reduction (IMR) assay at baseline. The cognitive performance of participants was measured through neuropsychological tests at baseline and annual follow-up (average follow-up period of 1.5 years). The predictive value of plasma Aß42 and t-tau for cognitive status was evaluated. We found that higher levels of Aß42 and t-tau are associated with lower episodic verbal memory performance at baseline and cognitive decline over the course of follow-up. While Aß42 or t-tau alone had moderate-to-high discriminatory value in the identification of future cognitive decline, the product of Aß42 and t-tau offered greater differential value. These preliminary results might suggest that high levels of plasma Aß42 and t-tau in amnestic MCI are associated with later cognitive decline. A further replication with a larger sample over a longer time period to validate and determine their long-term predictive value is warranted.
Assuntos
Amnésia/sangue , Peptídeos beta-Amiloides/sangue , Cognição/fisiologia , Disfunção Cognitiva/sangue , Fragmentos de Peptídeos/sangue , Proteínas tau/sangue , Idoso , Idoso de 80 Anos ou mais , Amnésia/psicologia , Biomarcadores/sangue , Estudos de Casos e Controles , Disfunção Cognitiva/psicologia , Progressão da Doença , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Estudos ProspectivosRESUMO
Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder and is triggered via abnormal accumulation of amyloid-ß peptide (Aß). Aggregated Aß is responsible for disrupting calcium homeostasis, inducing neuroinflammation, and promoting neurodegeneration. In this study, we generated curcuminoid submicron particle (CSP), which reduce the average size to ~60 nm in diameter. CSP had elevated the bioavailability in vivo and better neuroprotective effect against oligomeric Aß than un-nanosized curcuminoids in vitro. Two months of CSP consumption reversed spatial memory deficits and the loss of a calcium binding protein calbindin-D28k in the hippocampus of AD mouse model. In addition, CSP consumption lowered amyloid plaques and astrogliosis in vivo and enhanced microglial Aß phagocytosis in vitro, implying that the beneficial effects of CSP also mediated via modulating neuroinflammation and enhancing amyloid clearance. Taken together, our study demonstrated the protective effects of CSP toward ameliorating the memory impairment and pathological deficits in AD mouse model.
RESUMO
Mcm10 has recently been found to play a crucial role in multiple steps of the DNA replication initiation process in eukaryotes. Here, we have examined the role of Mcm10 in assembling initiation factors at a well-characterized yeast replication origin, ARS1. We find that the pre-replication complex (pre-RC) components Cdc6 and Mcm7 associate with ARS1 in the mcm10-1 mutant, suggesting that establishment of the pre-RC is not compromised in this mutant. Association of Cdc45 with ARS1 is reduced in the mcm10-1 mutant, suggesting that Mcm10 is involved in recruiting Cdc45 to the pre-RC. We find that overexpression of either Mcm10-1 or Cdc45 suppresses the growth defect of mcm10-1, and that a physical interaction between Cdc45 and Mcm10 is disrupted in the mcm10-1 mutant. Our results show that interaction between the Mcm10 and Cdc45 proteins facilitates the recruitment of Cdc45 onto the ARS1 origin.
Assuntos
Proteínas de Transporte/fisiologia , Proteínas de Ciclo Celular/fisiologia , Proteínas de Ligação a DNA , Proteínas Nucleares/fisiologia , Origem de Replicação , Proteínas de Saccharomyces cerevisiae/fisiologia , Saccharomyces cerevisiae/fisiologia , Proteínas de Ciclo Celular/genética , Proteínas Cromossômicas não Histona , Proteínas de Manutenção de Minicromossomo , Mutação , Saccharomyces cerevisiae/genéticaRESUMO
Alzheimer's disease (AD) is the most common form of dementia. The deposition of brain amyloid-ß peptides (Aß), which are cleaved from amyloid precursor protein (APP), is one of the pathological hallmarks of AD. Aß-induced oxidative stress and neuroinflammation play important roles in the pathogenesis of AD. Antroquinonol, a ubiquinone derivative isolated from Antrodia camphorata, has been shown to reduce oxidative stress and inflammatory cytokines via activating the nuclear transcription factor erythroid-2-related factor 2 (Nrf2) pathway, which is downregulated in AD. Therefore, we examined whether antroquinonol could improve AD-like pathological and behavioral deficits in the APP transgenic mouse model. We found that antroquinonol was able to cross the blood-brain barrier and had no adverse effects via oral intake. Two months of antroquinonol consumption improved learning and memory in the Morris water maze test, reduced hippocampal Aß levels, and reduced the degree of astrogliosis. These effects may be mediated through the increase of Nrf2 and the decrease of histone deacetylase 2 (HDAC2) levels. These findings suggest that antroquinonol could have beneficial effects on AD-like deficits in APP transgenic mouse.
Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/fisiopatologia , Peptídeos beta-Amiloides/metabolismo , Aprendizagem Espacial/efeitos dos fármacos , Memória Espacial/efeitos dos fármacos , Ubiquinona/análogos & derivados , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/patologia , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animais , Comportamento Animal , Barreira Hematoencefálica/metabolismo , Modelos Animais de Doenças , Hipocampo/metabolismo , Hipocampo/patologia , Histona Desacetilase 2/metabolismo , Camundongos , Camundongos Transgênicos , Fator 2 Relacionado a NF-E2/metabolismo , Ratos , Ubiquinona/administração & dosagem , Ubiquinona/efeitos adversos , Ubiquinona/farmacocinética , Ubiquinona/farmacologiaRESUMO
Proteinaceous inclusions are common hallmarks of many neurodegenerative diseases. TDP-43 proteinopathies, consisting of several neurodegenerative diseases, including frontotemporal lobar dementia (FTLD) and amyotrophic lateral sclerosis (ALS), are characterized by inclusion bodies formed by polyubiquitinated and hyperphosphorylated full-length and truncated TDP-43. The structural properties of TDP-43 aggregates and their relationship to pathogenesis are still ambiguous. Here we demonstrate that the recombinant full-length human TDP-43 forms structurally stable, spherical oligomers that share common epitopes with an anti-amyloid oligomer-specific antibody. The TDP-43 oligomers are stable, have exposed hydrophobic surfaces, exhibit reduced DNA binding capability and are neurotoxic in vitro and in vivo. Moreover, TDP-43 oligomers are capable of cross-seeding Alzheimer's amyloid-ß to form amyloid oligomers, demonstrating interconvertibility between the amyloid species. Such oligomers are present in the forebrain of transgenic TDP-43 mice and FTLD-TDP patients. Our results suggest that aside from filamentous aggregates, TDP-43 oligomers may play a role in TDP-43 pathogenesis.
Assuntos
Amiloide/química , Córtex Cerebral/patologia , Proteínas de Ligação a DNA/química , Demência Frontotemporal/patologia , Agregação Patológica de Proteínas/patologia , Proteinopatias TDP-43/patologia , Sequência de Aminoácidos , Amiloide/imunologia , Animais , Anticorpos Monoclonais/biossíntese , Anticorpos Monoclonais/química , Linhagem Celular Tumoral , Córtex Cerebral/química , Córtex Cerebral/imunologia , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/imunologia , Embrião de Mamíferos , Epitopos/química , Epitopos/imunologia , Escherichia coli/genética , Escherichia coli/metabolismo , Demência Frontotemporal/genética , Demência Frontotemporal/imunologia , Expressão Gênica , Células HEK293 , Humanos , Injeções Intraventriculares , Masculino , Camundongos , Dados de Sequência Molecular , Neurônios/química , Neurônios/imunologia , Neurônios/patologia , Cultura Primária de Células , Agregados Proteicos , Agregação Patológica de Proteínas/genética , Agregação Patológica de Proteínas/imunologia , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Proteinopatias TDP-43/genética , Proteinopatias TDP-43/imunologiaRESUMO
The identification of blood biomarkers for Alzheimer's disease (AD) could contribute for improvement in early diagnosis. To define AD biomarkers, we compared serum/plasma levels of amyloid ß (Aß), tau, cytokines, and biometals between AD and non-AD groups. Cognitive impairment was assessed by Mini-Mental Status Examination (MMSE) and Clinical Dementia Rating scales. Plasma concentrations of total Aß, Aß(42), tumor necrosis factor α (TNF-α), and interleukin 6 were quantified by immunoassays. Serum biometal concentrations were determined using flame atomic absorption spectrometry. We found that serum zinc (Zn) was lower in patients with AD. After controlling for age, the MMSE score correlated with both TNF-α and total Aß levels in the AD group, while the MMSE score correlated with iron only in the non-AD group. Our finding that blood Zn, TNF-α, and total Aß are possible biomarkers for AD diagnosis and prognosis validates the pervious publication on potential biomarker in the Taiwanese population.
Assuntos
Doença de Alzheimer/sangue , Disfunção Cognitiva/sangue , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/epidemiologia , Doença de Alzheimer/genética , Peptídeos beta-Amiloides/sangue , Biomarcadores/sangue , Disfunção Cognitiva/genética , Cobre/sangue , Humanos , Interleucina-6/sangue , Ferro/sangue , Masculino , Escalas de Graduação Psiquiátrica , Índice de Gravidade de Doença , Espectrofotometria Atômica , Taiwan/epidemiologia , Fator de Necrose Tumoral alfa/sangue , Zinco/sangue , Proteínas tau/sangueRESUMO
Alzheimer's disease (AD), a chronic neurodegenerative disorder associated with the abnormal accumulations of amyloid ß (Aß) peptide and oxidative stress in the brain, is the most common form of dementia among the elderly. Crude caffeine (CC), a major by-product of the decaffeination of coffee, has potent hydrophilic antioxidant activity and may reduce inflammatory processes. Here, we showed that CC and pure caffeine intake had beneficial effects in a mouse model of AD. Administration of CC or pure caffeine for 2months partially prevented memory impairment in AD mice, with CC having greater effects than pure caffeine. Furthermore, consumption of CC, but not pure caffeine, reduced the Aß(1-42) levels and the number of amyloid plaques in the hippocampus. Moreover, CC and caffeine protected primary neurons from Aß-induced cell death and suppressed Aß-induced caspase-3 activity. Our data indicate that CC may contain prophylactic agents against the cell death and the memory impairment in AD.
Assuntos
Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Cafeína/administração & dosagem , Coffea/química , Memória/efeitos dos fármacos , Extratos Vegetais/administração & dosagem , Doença de Alzheimer/genética , Doença de Alzheimer/psicologia , Peptídeos beta-Amiloides/genética , Animais , Caspase 3/genética , Caspase 3/metabolismo , Modelos Animais de Doenças , Humanos , Masculino , Aprendizagem em Labirinto , Camundongos , Camundongos Endogâmicos C57BL , Camundongos TransgênicosRESUMO
Amyloid precursor protein (APP) mutations associated with familial Alzheimer's disease (AD) usually lead to increases in amyloid ß-protein (Aß) levels or aggregation. Here, we identified a novel APP mutation, located within the Aß sequence (Aß(D7H)), in a Taiwanese family with early onset AD and explored the pathogenicity of this mutation. Cellular and biochemical analysis reveal that this mutation increased Aß production, Aß42/40 ratio and prolonged Aß42 oligomer state with higher neurotoxicity. Because the D7H mutant Aß has an additional metal ion-coordinating residue, histidine, we speculate that this mutation may promote susceptibility of Aß to ion. When co-incubated with Zn(2+) or Cu(2+), Aß(D7H) aggregated into low molecular weight oligomers. Together, the D7H mutation could contribute to AD pathology through a "double punch" effect on elevating both Aß production and oligomerization. Although the pathogenic nature of this mutation needs further confirmation, our findings suggest that the Aß N-terminal region potentially modulates APP processing and Aß aggregation, and further provides a genetic indication of the importance of Zn(2+) and Cu(2+) in the etiology of AD.
Assuntos
Doença de Alzheimer/genética , Peptídeos beta-Amiloides/genética , Precursor de Proteína beta-Amiloide/genética , Cobre/química , Fragmentos de Peptídeos/genética , Zinco/química , Doença de Alzheimer/metabolismo , Sequência de Aminoácidos , Peptídeos beta-Amiloides/química , Precursor de Proteína beta-Amiloide/química , Ácido Aspártico/química , Ácido Aspártico/genética , Sequência de Bases , Células Cultivadas , Cobre/metabolismo , Feminino , Células HEK293 , Histidina/química , Histidina/genética , Humanos , Pessoa de Meia-Idade , Dados de Sequência Molecular , Mutação , Fragmentos de Peptídeos/química , Polimerização , Taiwan , Zinco/metabolismoRESUMO
BACKGROUND: Obesity is a multifactorial disease that arises from complex interactions between genetic predisposition and environmental factors. Leptin is central to the regulation of energy metabolism and control of body weight in mammals. METHODOLOGY/PRINCIPAL FINDINGS: To better recapitulate the complexity of human obesity syndrome, we applied N-ethyl-N-nitrosourea (ENU) mutagenesis in combination with a set of metabolic assays in screening mice for obesity. Mapping revealed linkage to the chromosome 6 within a region containing mouse Leptin gene. Sequencing on the candidate genes identified a novel T-to-A mutation in the third exon of Leptin gene, which translates to a V145E amino acid exchange in the leptin propeptide. Homozygous Leptin(145E/145E) mutant mice exhibited morbid obesity, accompanied by adipose hypertrophy, energy imbalance, and liver steatosis. This was further associated with severe insulin resistance, hyperinsulinemia, dyslipidemia, and hyperleptinemia, characteristics of human obesity syndrome. Hypothalamic leptin actions in inhibition of orexigenic peptides NPY and AgRP and induction of SOCS1 and SOCS3 were attenuated in Leptin(145E/145E) mice. Administration of exogenous wild-type leptin attenuated hyperphagia and body weight increase in Leptin(145E/145E) mice. However, mutant V145E leptin coimmunoprecipitated with leptin receptor, suggesting that the V145E mutation does not affect the binding of leptin to its receptor. Molecular modeling predicted that the mutated residue would form hydrogen bond with the adjacent residues, potentially affecting the structure and formation of an active complex with leptin receptor within that region. CONCLUSIONS/SIGNIFICANCE: Thus, our evolutionary, structural, and in vivo metabolic information suggests the residue 145 as of special function significance. The mouse model harboring leptin V145E mutation will provide new information on the current understanding of leptin biology and novel mouse model for the study of human obesity syndrome.
Assuntos
Etilnitrosoureia , Hiperinsulinismo/genética , Leptina/genética , Mutagênese , Mutação , Obesidade Mórbida/genética , Animais , Peso Corporal , Evolução Molecular , Éxons , Predisposição Genética para Doença , Homozigoto , Humanos , Leptina/metabolismo , Camundongos , Receptores para Leptina/genéticaRESUMO
Amyloid-beta (Abeta) peptides, widely presumed to cause Alzheimer's disease, increased mouse neuronal expression of collagen VI through a mechanism involving transforming growth factor signaling. Reduction of collagen VI augmented Abeta neurotoxicity, whereas treatment of neurons with soluble collagen VI blocked the association of Abeta oligomers with neurons, enhanced Abeta aggregation and prevented neurotoxicity. These results identify collagen VI as an important component of the neuronal injury response and demonstrate its neuroprotective potential.
Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Colágeno Tipo VI/metabolismo , Neurônios/metabolismo , Fragmentos de Peptídeos/metabolismo , Doença de Alzheimer/fisiopatologia , Peptídeos beta-Amiloides/genética , Animais , Astrócitos/citologia , Astrócitos/metabolismo , Colágeno Tipo VI/genética , Giro Denteado/metabolismo , Giro Denteado/patologia , Giro Denteado/fisiopatologia , Humanos , Camundongos , Camundongos Transgênicos , Neurônios/patologia , Análise de Sequência com Séries de Oligonucleotídeos , Fragmentos de Peptídeos/genética , Ligação Proteica/fisiologia , Transdução de Sinais/fisiologia , Fator de Crescimento Transformador beta/metabolismoRESUMO
Oxidative stress is involved in many neurodegenerative processes leading to age-related cognitive decline. Coffee, a widely consumed beverage, is rich in many bioactive components, including polyphenols with antioxidant potential. In this study, regular and decaffeinated samples of both roasted and green coffee all showed high hydrophilic antioxidant activity in vitro, whereas lipophilic antioxidant activities were on average 30-fold higher in roasted than in green coffee samples. In primary neuronal cell culture, pretreatment with green and roasted coffees (regular and decaffeinated) protected against subsequent H(2)O(2)-induced oxidative stress and improved neuronal cell survival (green coffees increased neuron survival by 78%, compared to 203% by roasted coffees). All coffee extracts inhibited ERK1/2 activation, indicating a potential attenuating effect in stress-induced neuronal cell death. Interestingly, only roasted coffee extracts inhibited JNK activation, evidencing a distinctive neuroprotective benefit. Analysis of coffee phenolic compounds revealed that roasted coffees contained high levels of chlorogenic acid lactones (CGLs); a significant correlation between CGLs and neuroprotective efficacy was observed (R(2) = 0.98). In conclusion, this study showed that roasted coffees are high in lipophilic antioxidants and CGLs, can protect neuronal cells against oxidative stress, and may do so by modulation of the ERK1/2 and JNK signaling pathways.
Assuntos
Antioxidantes/farmacologia , Ácido Clorogênico/farmacologia , Café/química , Lactonas/farmacologia , Fármacos Neuroprotetores/farmacologia , Animais , Antioxidantes/química , Sobrevivência Celular , Células Cultivadas , Ácido Clorogênico/análise , Coffea/química , Manipulação de Alimentos , Lactonas/análise , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fármacos Neuroprotetores/análise , Estresse Oxidativo/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacosRESUMO
Neuronal expression of familial Alzheimer's disease-mutant human amyloid precursor protein (hAPP) and hAPP-derived amyloid-beta (Abeta) peptides causes synaptic dysfunction, inflammation and abnormal cerebrovascular tone in transgenic mice. Fatty acids may be involved in these processes, but their contribution to Alzheimer's disease pathogenesis is uncertain. We used a lipidomics approach to generate a broad profile of fatty acids in brain tissues of hAPP-expressing mice and found an increase in arachidonic acid and its metabolites, suggesting increased activity of the group IV isoform of phospholipase A(2) (GIVA-PLA(2)). The levels of activated GIVA-PLA(2) in the hippocampus were increased in individuals with Alzheimer's disease and in hAPP mice. Abeta caused a dose-dependent increase in GIVA-PLA(2) phosphorylation in neuronal cultures. Inhibition of GIVA-PLA(2) diminished Abeta-induced neurotoxicity. Genetic ablation or reduction of GIVA-PLA(2) protected hAPP mice against Abeta-dependent deficits in learning and memory, behavioral alterations and premature mortality. Inhibition of GIVA-PLA(2) may be beneficial in the treatment and prevention of Alzheimer's disease.