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1.
J Leukoc Biol ; 110(6): 1005-1022, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34494312

RESUMO

Chronic neuroinflammation has been shown to exert adverse influences on the pathology of Alzheimer's disease (AD), associated with the release of abundant proinflammatory mediators by excessively activated microglia, causing synaptic dysfunction, neuronal degeneration, and memory deficits. Thus, the prevention of microglial activation-associated neuroinflammation is important target for deterring neurodegenerative disorders. Peony seed oil (PSO) is a new food resource, rich in α-linolenic acid, the precursor of long chain omega-3 polyunsaturated fatty acids, including docosahexaenoic acid and eicosapentaenoic acid, which exhibit anti-inflammatory properties by altering cell membrane phospholipid fatty acid compositions, disrupting lipid rafts, and inhibiting the activation of the proinflammatory transcription factor NF-κB. However, few studies have examined the anti-neuroinflammatory effects of PSO in AD, and the relevant molecular mechanisms remain unclear. Presenilin1/2 conditional double knockout (PS cDKO) mice display obvious AD-like phenotypes, such as neuroinflammatory responses, synaptic dysfunction, and cognitive deficits. Here, we assessed the potential neuroprotective effects of PSO against neuroinflammation-mediated cognitive deficits in PS cDKO using behavioral tests and molecular biologic analyses. Our study demonstrated that PSO suppressed microglial activation and neuroinflammation through the down-regulation of proinflammatory mediators, such as inducible NOS, COX-2, IL-1ß, and TNF-α, in the prefrontal cortex and hippocampus of PS cDKO mice. Further, PSO significantly lessened memory impairment by reversing hyperphosphorylated tau and synaptic proteins deficits in PS cDKO mice. Importantly, PSO's therapeutic effects on cognitive deficits were due to inhibiting neuroinflammatory responses mediated by NF-κB signaling pathway. Taken together, PSO may represent an effective dietary supplementation to restrain the neurodegenerative processes of AD.


Assuntos
Doença de Alzheimer , Anti-Inflamatórios/farmacologia , Disfunção Cognitiva , Microglia/efeitos dos fármacos , Óleos de Plantas/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/patologia , Modelos Animais de Doenças , Inflamação , Camundongos , Camundongos Knockout , NF-kappa B/metabolismo , Fármacos Neuroprotetores/farmacologia , Paeonia , Presenilina-1/deficiência , Presenilina-2/deficiência , Sementes , Transdução de Sinais/efeitos dos fármacos
2.
Neural Plast ; 2021: 8814616, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33505459

RESUMO

Neuroinflammation is considered as one of the crucial pathogenesis in promoting neurodegenerative progress of Alzheimer's disease (AD). As complementary and alternative therapy, electroacupuncture (EA) stimulation has been widely used in clinical practice for anti-inflammation. However, whether EA promotes the cognitive deficits resulting from neuroinflammation in AD remains unclear. In this study, the presenilin 1 and 2 conditional double knockout (PS cDKO) mice, exhibited a series of AD-like pathology, robust neuroinflammatory responses, and memory deficits, were used to evaluate the potential neuroprotective effect of EA at Baihui (GV 20) and Shenting (GV 24) by behavioral testing, electrophysiology recording, and molecular biology analyzing. First, we observed that EA improved memory deficits and impaired synaptic plasticity. Moreover, EA possesses an ability to suppress the hyperphosphorylated tau and robust elevated NLRP3, ASC, Caspase-1, IL-1ß, and IL-18 in PS cDKO mice. Importantly, MCC950, a potent and selective inhibitor of NLPR3 inflammasome, has similar effects on inhibiting the hyperphosphorylated tau and the robust elevated NLRP3 components and neuroinflammatory responses of PS cDKO mice as well as EA treatment. Furthermore, EA treatment is not able to further improve the AD-like phenotypes of PS cDKO mice in combination with the MCC950 administration. Therefore, EA stimulation at GV 20 and GV 24 acupoints may be a potential alternative therapy for deterring cognitive deficits in AD through suppression of NLRP3 inflammasome activation.


Assuntos
Disfunção Cognitiva/terapia , Eletroacupuntura/métodos , Mediadores da Inflamação/antagonistas & inibidores , Proteína 3 que Contém Domínio de Pirina da Família NLR/antagonistas & inibidores , Presenilina-1/deficiência , Presenilina-2/deficiência , Animais , Disfunção Cognitiva/metabolismo , Furanos/farmacologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Indenos/farmacologia , Mediadores da Inflamação/metabolismo , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Presenilina-1/genética , Presenilina-2/genética , Sulfonamidas/farmacologia
3.
Cells ; 10(2)2021 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-33494218

RESUMO

Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder in which learning, memory and cognitive functions decline progressively. Familial forms of AD (FAD) are caused by mutations in amyloid precursor protein (APP), presenilin 1 (PSEN1) and presenilin 2 (PSEN2) genes. Presenilin 1 (PS1) and its homologue, presenilin 2 (PS2), represent, alternatively, the catalytic core of the γ-secretase complex that, by cleaving APP, produces neurotoxic amyloid beta (Aß) peptides responsible for one of the histopathological hallmarks in AD brains, the amyloid plaques. Recently, PSEN1 FAD mutations have been associated with a loss-of-function phenotype. To investigate whether this finding can also be extended to PSEN2 FAD mutations, we studied two processes known to be modulated by PS2 and altered by FAD mutations: Ca2+ signaling and mitochondrial function. By exploiting neurons derived from a PSEN2 knock-out (PS2-/-) mouse model, we found that, upon IP3-generating stimulation, cytosolic Ca2+ handling is not altered, compared to wild-type cells, while mitochondrial Ca2+ uptake is strongly compromised. Accordingly, PS2-/- neurons show a marked reduction in endoplasmic reticulum-mitochondria apposition and a slight alteration in mitochondrial respiration, whereas mitochondrial membrane potential, and organelle morphology and number appear unchanged. Thus, although some alterations in mitochondrial function appear to be shared between PS2-/- and FAD-PS2-expressing neurons, the mechanisms leading to these defects are quite distinct between the two models. Taken together, our data appear to be difficult to reconcile with the proposal that FAD-PS2 mutants are loss-of-function, whereas the concept that PS2 plays a key role in sustaining mitochondrial function is here confirmed.


Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Sinalização do Cálcio , Mitocôndrias/metabolismo , Presenilina-2/deficiência , Trifosfato de Adenosina/biossíntese , Animais , Respiração Celular , Ciclo do Ácido Cítrico , Citosol/metabolismo , Retículo Endoplasmático/metabolismo , Glicólise , Potencial da Membrana Mitocondrial , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurônios/metabolismo , Fosforilação Oxidativa , Fenótipo , Presenilina-2/metabolismo
4.
Neurobiol Dis ; 136: 104719, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31862541

RESUMO

Patients with Alzheimer's disease (AD) experience seizures at higher rates than the general population of that age, suggesting an underexplored role of hyperexcitability in AD. Genetic variants in presenilin (PSEN) 1 and 2 genes lead to autosomal dominant early-onset AD (ADAD); patients with PSEN gene variants also report seizures. Pharmacological control of seizures in AD may be disease-modifying. Preclinical efficacy of FDA-approved antiseizure drugs (ASDs) is well defined in young adult rodents; however, the efficacy of ASDs in aged rodents with chronic seizures is less clear. The mechanism by which ADAD genes lead to AD remains unclear, and even less studied is the pathogenesis of epilepsy in AD. PSEN variants generally all result in a biochemical loss of function (De Strooper, 2007). We herein determined whether well-established models of acute and chronic seizure could be used to explore the relationship between AD genes and seizures through investigating whether loss of normal PSEN2 function age-dependently influenced susceptibility to seizures and/or corneal kindling acquisition. PSEN2 knockout (KO) and age-matched wild-type (WT) mice were screened from 2- to 10-months-old to establish age-dependent focal seizure threshold. Additionally, PSEN2 KO and WT mice aged 2- and 8-months-old underwent corneal kindling such that mice were aged 3- and 9-months old at the beginning of ASD efficacy testing. We then defined the dose-dependent efficacy of mechanistically distinct ASDs on kindled seizures of young versus aged mice to better understand the applicability of corneal kindling to real-world use for geriatric patients. PSEN2 KO mice demonstrated early-life reductions in seizure threshold. However, kindling acquisition was delayed in 2-month-old PSEN2 KO versus WT mice. Young male WT mice took 24.3 ± 1.3 (S.E.M.) stimulations to achieve kindling criterion, whereas age-matched PSEN2 KO male mice took 41.2 ± 1.1 stimulations (p < .0001). The rate of kindling acquisition of 8-month-old mice was no longer different from WT. This study demonstrates that loss of normal PSEN2 function is associated with age-dependent changes in the in vivo susceptibility to acute seizures and kindling. Loss of normal PSEN2 function may be an underexplored molecular contributor to seizures. The use of validated models of chronic seizures in aged rodents may uncover age-related changes in susceptibility to epileptogenesis and/or ASD efficacy in mice with AD-associated genotypes, which may benefit the management of seizures in AD.


Assuntos
Predisposição Genética para Doença , Excitação Neurológica/metabolismo , Presenilina-2/deficiência , Convulsões/metabolismo , Animais , Feminino , Predisposição Genética para Doença/genética , Excitação Neurológica/genética , Masculino , Camundongos , Camundongos Knockout , Presenilina-2/genética , Convulsões/genética
5.
Mol Neurobiol ; 55(6): 5232-5242, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28879407

RESUMO

MicroRNAs are small non-coding RNAs that function as regulators of gene expression. The altered expression of microRNAs influences the pathogenesis of Alzheimer's disease. Many researchers have focused on studies based on the relatively distinctive etiology of familial Alzheimer's disease due to the absence of risk factors in the pathogenesis of sporadic Alzheimer's disease. Although there is a limitation in Alzheimer's disease studies, both Alzheimer's disease types have a common risk factor-aging. No study to date has examined the aging factor in Alzheimer's disease animal models with microRNAs. To investigate the effect of aging on the changes in microRNA expressions in the Alzheimer's disease animal model, we selected 37 hippocampal microRNAs whose expression in 12- and 18-month aged mice changed significantly using microRNA microarray. On the basis of bioinformatics databases, 30 hippocampal microRNAs and their putative targets of PSEN1/PSEN2 double knockout mice were included in 28 pathways such as the wnt signaling pathway and ubiquitin-mediated proteolysis pathway. Cortical microRNAs and its putative targets involved in pathological aging were included in only four pathways such as the heparin sulfate biosynthesis. The altered expressions of these hippocampal microRNAs were associated to the imbalance between neurotoxic and neuroprotective functions and seemed to affect neurodegeneration in PSEN1/PSEN2 double knockout mice more severely than in wild-type mice. This microRNA profiling suggests that microRNAs play potential roles in the normal aging process, as well as in the Alzheimer's disease process.


Assuntos
Envelhecimento/genética , Perfilação da Expressão Gênica , MicroRNAs/genética , Presenilina-1/deficiência , Presenilina-2/deficiência , Animais , Regulação da Expressão Gênica no Desenvolvimento , Hipocampo/metabolismo , Hipocampo/patologia , Camundongos Knockout , MicroRNAs/metabolismo , Presenilina-1/genética , Presenilina-1/metabolismo , Presenilina-2/genética , Presenilina-2/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
6.
Sci Rep ; 6: 26874, 2016 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-27240887

RESUMO

Notch signaling is known to control early pancreatic differentiation through Ngn3 repression. In later stages, downstream of Notch, the Presenilins are still required to maintain the endocrine fate allocation. Amongst their multiple targets, it remains unclear which one actually controls the maintenance of the fate of the early islets. Conditional deletions of the Notch effector RBP-Jκ with lineage tracing in Presenilin-deficient endocrine progenitors, demonstrated that this factor is central to the control of the fate through a non-canonical Notch mechanism. RBP-Jκ mice exhibit normal islet morphogenesis and function, however, a fraction of the progenitors fails to differentiate and develop into disorganized masses resembling acinar to ductal metaplasia and chronic pancreatitis. A subsequent deletion of RBP-Jκ in forming ß-cells led to the transdifferentiation into the other endocrine cells types, indicating that this factor still mediates the maintenance of the fate within the endocrine lineage itself. These results highlight the dual importance of Notch signaling for the endocrine lineage. Even after Ngn3 expression, Notch activity is required to maintain both fate and maturation of the Ngn3 progenitors. In a subset of the cells, these alterations of Notch signaling halt their differentiation and leads to acinar to ductal metaplasia.


Assuntos
Células Enteroendócrinas/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteína de Ligação a Sequências Sinal de Recombinação J de Imunoglobina/genética , Ilhotas Pancreáticas/metabolismo , Morfogênese/genética , Células-Tronco Embrionárias Murinas/metabolismo , Células Acinares/citologia , Células Acinares/metabolismo , Animais , Animais Geneticamente Modificados , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Diferenciação Celular , Linhagem da Célula/genética , Embrião de Mamíferos , Células Enteroendócrinas/citologia , Feminino , Genes Reporter , Proteína de Ligação a Sequências Sinal de Recombinação J de Imunoglobina/deficiência , Integrases/genética , Integrases/metabolismo , Ilhotas Pancreáticas/citologia , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Masculino , Metaplasia/genética , Metaplasia/metabolismo , Metaplasia/patologia , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco Embrionárias Murinas/citologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Presenilina-1/deficiência , Presenilina-1/genética , Presenilina-2/deficiência , Presenilina-2/genética , Receptores Notch/genética , Receptores Notch/metabolismo , Transdução de Sinais
7.
Mol Neurobiol ; 53(5): 3428-3438, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26081153

RESUMO

The importance of presenilin-dependent γ-secretase protease activities in the development, neurogenesis, and immune system is highlighted by the diversity of its substrates and characterization of Psen1- and Psen2-deficient transgenic animals. Functional differences between presenilin 1 (PS1) and presenilin 2 (PS2) are incompletely understood. In this study, we have identified a Psen2-specific function, not shared by Psen1 in Toll-like receptor signaling. We show that immortalized fibroblasts and bone marrow-derived macrophages from Psen2- but not Psen1-deficient mice display reduced responsiveness to lipopolysaccharide (LPS) with decreased nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) activity and diminished pro-inflammatory cytokine production. In whole animal in vivo responses, Psen2-deficient animals have abnormal systemic production of LPS-stimulated pro-inflammatory cytokines. Mechanistically, we demonstrate that Psen2 deficiency is paralleled by reduced transcription of tlr4 mRNA and loss of LPS-induced tlr4 mRNA transcription regulation. These observations illustrate a novel PS2-dependent means of modulating LPS-mediated immune responses and identify a functional distinction between PS1 and PS2 in innate immunity.


Assuntos
Imunidade Inata/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Presenilina-2/deficiência , Animais , Citocinas/metabolismo , Embrião de Mamíferos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Mediadores da Inflamação/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/metabolismo , Presenilina-2/metabolismo , Células RAW 264.7 , Transdução de Sinais/efeitos dos fármacos , Receptor 4 Toll-Like/genética , Receptor 4 Toll-Like/metabolismo , Transcrição Gênica/efeitos dos fármacos
8.
J Neurosci ; 34(48): 15912-22, 2014 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-25429133

RESUMO

Mutations in the presenilin (PSEN1 and PSEN2) genes are linked to familial Alzheimer's disease (AD) and cause loss of its essential function. Complete inactivation of presenilins in excitatory neurons of the adult mouse cerebral cortex results in progressive memory impairment and age-dependent neurodegeneration, recapitulating key features of AD. In this study, we examine the effects of varying presenilin dosage on cortical neuron survival by generating presenilin-1 conditional knock-out (PS1 cKO) mice carrying two, one, or zero copies of the PS2 gene. We found that PS1 cKO;PS2(+/-) mice at 16 months exhibit marked neurodegeneration in the cerebral cortex with ∼17% reduction of cortical volume and neuron number, as well as astrogliosis and microgliosis compared with ∼50% reduction of cortical volume and neuron number in PS1 cKO;PS2(-/-) mice. Moreover, there are more apoptotic neurons labeled by activated caspase-3 immunoreactivity and TUNEL assay in PS1 cKO;PS2(+/-) mice at 16 months, whereas apoptotic neurons are increased in the PS1 cKO;PS2(-/-) cerebral cortex at 4 months. The accumulation of the C-terminal fragments of the amyloid precursor protein is inversely correlated with PS dosage. Interestingly, levels of PS2 are higher in the cerebral cortex of PS1 cKO mice, suggesting a compensatory upregulation that may provide protection against neurodegeneration in these mice. Together, our findings show that partial to complete loss of presenilin activity causes progressively more severe neurodegeneration in the mouse cerebral cortex during aging, suggesting that impaired presenilin function by PSEN mutations may lead to neurodegeneration and dementia in AD.


Assuntos
Envelhecimento/metabolismo , Córtex Cerebral/metabolismo , Neurônios/metabolismo , Presenilina-1/deficiência , Presenilina-2/deficiência , Envelhecimento/patologia , Animais , Sobrevivência Celular/fisiologia , Córtex Cerebral/patologia , Feminino , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Neurônios/patologia
9.
J Neurosci ; 34(9): 3320-39, 2014 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-24573290

RESUMO

Overexpression and/or abnormal cleavage of amyloid precursor protein (APP) are linked to Alzheimer's disease (AD) development and progression. However, the molecular mechanisms regulating cellular levels of APP or its processing, and the physiological and pathological consequences of altered processing are not well understood. Here, using mouse and human cells, we found that neuronal damage induced by UV irradiation leads to specific APP, APLP1, and APLP2 decline by accelerating their secretase-dependent processing. Pharmacological inhibition of endosomal/lysosomal activity partially protects UV-induced APP processing implying contribution of the endosomal and/or lysosomal compartments in this process. We found that a biological consequence of UV-induced γ-secretase processing of APP is impairment of APP axonal transport. To probe the functional consequences of impaired APP axonal transport, we isolated and analyzed presumptive APP-containing axonal transport vesicles from mouse cortical synaptosomes using electron microscopy, biochemical, and mass spectrometry analyses. We identified a population of morphologically heterogeneous organelles that contains APP, the secretase machinery, molecular motors, and previously proposed and new residents of APP vesicles. These possible cargoes are enriched in proteins whose dysfunction could contribute to neuronal malfunction and diseases of the nervous system including AD. Together, these results suggest that damage-induced APP processing might impair APP axonal transport, which could result in failure of synaptic maintenance and neuronal dysfunction.


Assuntos
Precursor de Proteína beta-Amiloide/metabolismo , Transporte Axonal/efeitos da radiação , Axônios/efeitos da radiação , Regulação da Expressão Gênica/efeitos da radiação , Neurônios/citologia , Raios Ultravioleta , Precursor de Proteína beta-Amiloide/deficiência , Animais , Axônios/efeitos dos fármacos , Axônios/metabolismo , Axônios/ultraestrutura , Células Cultivadas , Embrião de Mamíferos , Hipocampo/citologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neuroblastoma/patologia , Neurônios/efeitos da radiação , Presenilina-1/deficiência , Presenilina-2/deficiência , Transfecção
10.
J Biol Chem ; 288(49): 35222-36, 2013 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-24145027

RESUMO

Presenilins, the catalytic components of the γ-secretase complex, are upstream regulators of multiple cellular pathways via regulation of gene transcription. However, the underlying mechanisms and the genes regulated by these pathways are poorly characterized. In this study, we identify Tequila and its mammalian ortholog Prss12 as genes negatively regulated by presenilins in Drosophila larval brains and mouse embryonic fibroblasts, respectively. Prss12 encodes the serine protease neurotrypsin, which cleaves the heparan sulfate proteoglycan agrin. Altered neurotrypsin activity causes serious synaptic and cognitive defects; despite this, the molecular processes regulating neurotrypsin expression and activity are poorly understood. Using γ-secretase drug inhibitors and presenilin mutants in mouse embryonic fibroblasts, we found that a mature γ-secretase complex was required to repress neurotrypsin expression and agrin cleavage. We also determined that PSEN1 endoproteolysis or processing of well known γ-secretase substrates was not essential for this process. At the transcriptional level, PSEN1/2 removal induced cyclic AMP response element-binding protein (CREB)/CREB-binding protein binding, accumulation of activating histone marks at the neurotrypsin promoter, and neurotrypsin transcriptional and functional up-regulation that was dependent on GSK3 activity. Upon PSEN1/2 reintroduction, this active epigenetic state was replaced by a methyl CpG-binding protein 2 (MeCP2)-containing repressive state and reduced neurotrypsin expression. Genome-wide analysis revealed hundreds of other mouse promoters in which CREB binding is similarly modulated by the presence/absence of presenilins. Our study thus identifies Tequila and neurotrypsin as new genes repressed by presenilins and reveals a novel mechanism used by presenilins to modulate CREB signaling based on controlling CREB recruitment.


Assuntos
Agrina/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Presenilina-1/metabolismo , Presenilina-2/metabolismo , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Células Cultivadas , Drosophila/genética , Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Regulação da Expressão Gênica , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Modelos Biológicos , Presenilina-1/deficiência , Presenilina-1/genética , Presenilina-2/deficiência , Presenilina-2/genética , Regiões Promotoras Genéticas , Transdução de Sinais
11.
Int J Mol Sci ; 14(9): 18457-69, 2013 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-24018889

RESUMO

We used forebrain-specific conditional presenilin 1 (PS1) and presenilin 2 (PS2) double knockout mice (dKO mice) that exhibit symptoms of neurodegenerative diseases, especially Alzheimer's disease, to investigate whether ibuprofen can rescue brain and periodontal tissue abnormalities by attenuating the inflammatory response. Mandibles were dissected for alveolar bone-height analysis. Maxillae were fixed and decalcified for histological observation and osteoclast detection. ELISA measurements from the hippocampus, cortex, and gingiva of the mandibular incisor teeth were used to assay inflammatory mediators. We confirmed periodontal tissue abnormalities and inflammatory responses in brain and periodontal tissues in naive nine- and 12-month-old dKO mice. The other two groups of age-matched dKO mice that received 375-ppm ibuprofen treatment for six consecutive months exhibited significantly attenuated damage in periodontal tissues and reduction in several inflammation-related factors in brain and periodontal tissues. Our findings showed that the anti-inflammatory drug ibuprofen significantly decreased inflammation through the cyclooxygenase (COX) pathway in brain and periodontal tissues in dKO mice, and then attenuated abnormalities in periodontal tissues. This suggests that ibuprofen could be an ideal drug for preventing both nervous system and periodontal tissue damage caused by inflammatory responses.


Assuntos
Ibuprofeno/uso terapêutico , Doenças Periodontais/tratamento farmacológico , Doenças Periodontais/metabolismo , Periodonto/metabolismo , Presenilina-1/deficiência , Presenilina-2/deficiência , Animais , Ensaio de Imunoadsorção Enzimática , Imuno-Histoquímica , Camundongos , Camundongos Knockout , Presenilina-1/genética , Presenilina-2/genética
12.
Proc Natl Acad Sci U S A ; 110(37): 15091-6, 2013 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-23918386

RESUMO

Presenilin (PS) plays a central role in the pathogenesis of Alzheimer's disease, and loss of PS causes progressive memory impairment and age-related neurodegeneration in the mouse cerebral cortex. In hippocampal neurons, PS is essential for neurotransmitter release, NMDA receptor-mediated responses, and long-term potentiation. PS is also involved in the regulation of calcium homeostasis, although the precise site of its action is less clear. Here we investigate the mechanism by which PS regulates synaptic function and calcium homeostasis using acute hippocampal slices from PS conditional knockout mice and primary cultured postnatal hippocampal neurons, in which PS is inducibly inactivated. Using two different calcium probes, Fura-2 and Mag-Fura-2, we found that inactivation of PS in primary hippocampal neurons does not affect calcium concentration in the endoplasmic reticulum. Rather, in the absence of PS, levels of ryanodine receptor (RyR) are reduced in the hippocampus, measured by Western analysis and radioligand binding assay, although the mRNA expression is unaffected. RyR-mediated function is also impaired, as indicated by reduced RyR agonist-induced calcium release from the ER and RyR-mediated synaptic responses in the absence of PS. Furthermore, knockdown of RyR expression in wild-type hippocampal neurons by two independent shRNAs to levels comparable with the RyR protein reduction in PS-deficient hippocampal neurons mimics the defects exhibited in calcium homeostasis and presynaptic function. Collectively, our findings show that PS regulates calcium homeostasis and synaptic function via RyR and suggest that disruption of intracellular calcium homeostasis may be an early pathogenic event leading to presynaptic dysfunction in Alzheimer's disease.


Assuntos
Hipocampo/metabolismo , Presenilina-1/metabolismo , Presenilina-2/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Animais , Sinalização do Cálcio , Células Cultivadas , Retículo Endoplasmático/metabolismo , Técnicas de Silenciamento de Genes , Homeostase , Camundongos , Camundongos Knockout , Neurônios/metabolismo , Presenilina-1/deficiência , Presenilina-1/genética , Presenilina-2/deficiência , Presenilina-2/genética , Terminações Pré-Sinápticas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/deficiência , Canal de Liberação de Cálcio do Receptor de Rianodina/genética
13.
J Biol Chem ; 287(14): 10933-44, 2012 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-22311977

RESUMO

Familial Alzheimer disease (FAD) is linked to mutations in the presenilin (PS) homologs. FAD mutant PS expression has several cellular consequences, including exaggerated intracellular Ca(2+) ([Ca(2+)](i)) signaling due to enhanced agonist sensitivity and increased magnitude of [Ca(2+)](i) signals. The mechanisms underlying these phenomena remain controversial. It has been proposed that PSs are constitutively active, passive endoplasmic reticulum (ER) Ca(2+) leak channels and that FAD PS mutations disrupt this function resulting in ER store overfilling that increases the driving force for release upon ER Ca(2+) release channel opening. To investigate this hypothesis, we employed multiple Ca(2+) imaging protocols and indicators to directly measure ER Ca(2+) dynamics in several cell systems. However, we did not observe consistent evidence that PSs act as ER Ca(2+) leak channels. Nevertheless, we confirmed observations made using indirect measurements employed in previous reports that proposed this hypothesis. Specifically, cells lacking PS or expressing a FAD-linked PS mutation displayed increased area under the ionomycin-induced [Ca(2+)](i) versus time curve (AI) compared with cells expressing WT PS. However, an ER-targeted Ca(2+) indicator revealed that this did not reflect overloaded ER stores. Monensin pretreatment selectively attenuated the AI in cells lacking PS or expressing a FAD PS allele. These findings contradict the hypothesis that PSs form ER Ca(2+) leak channels and highlight the need to use ER-targeted Ca(2+) indicators when studying ER Ca(2+) dynamics.


Assuntos
Canais de Cálcio/metabolismo , Cálcio/metabolismo , Retículo Endoplasmático/metabolismo , Presenilina-1/metabolismo , Presenilina-2/metabolismo , Alelos , Doença de Alzheimer/genética , Animais , Sinalização do Cálcio/efeitos dos fármacos , Linhagem Celular , Retículo Endoplasmático/efeitos dos fármacos , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Técnicas de Silenciamento de Genes , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Ionomicina/farmacologia , Cinética , Camundongos , Imagem Molecular , Mutação , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Presenilina-1/deficiência , Presenilina-1/genética , Presenilina-2/deficiência , Presenilina-2/genética , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Regulação para Cima/efeitos dos fármacos
14.
J Neuropathol Exp Neurol ; 71(2): 130-9, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22249458

RESUMO

Senile plaques composed of ß-amyloid (Aß) are a pathological hallmark of Alzheimer disease. Presenilin 2 (PS2) mutations increase Aß generation in the brains of Alzheimer disease patients, but the underlying mechanism of Aß generation by PS2 mutations remains to be clarified. The Aß is generated through the sequential cleavage of amyloid precursor protein by ß- and γ-secretases. Here, we show that the PS2 mutation N141I enhances the activity of ß-secretase and expression of the ß-site amyloid precursor protein cleavage enzyme 1, a major neuronal ß-secretase in the brains of PS2 transgenic mice and in PC12 cells overexpressing mutant PS2. In parallel with the increased activity of ß-secretase, activation of extracellular signal-regulated kinase (ERK), Aß1-40 and Aß1-42 levels, generation of reactive oxygen species, and lipid peroxidation were higher in the mutant mouse neurons and the PC12 cells. Colocalization of phosphorylated ERK (phospho-ERK) and ß-site amyloid precursor protein cleavage enzyme 1 with hydroxynonenal-histidine was found in the mutant brains. An ERK inhibitor U0126 and an antioxidant N-acetylcysteine prevented the expression and activity of ß-secretase, ERK activation, and reactive oxygen species generation in both neurons and PC12 cells expressing mutant PS2 in a dose-dependent manner. Together, these data suggest that oxidative stress-mediated ERK activation contributes to increases in ß-secretase and, thus, an increase of Aß generation in neuronal cells expressing mutant PS2.


Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Regulação Enzimológica da Expressão Gênica/genética , Mutação/genética , Neurônios/enzimologia , Presenilina-2/genética , Espécies Reativas de Oxigênio/metabolismo , Peptídeos beta-Amiloides/metabolismo , Animais , Ácido Aspártico Endopeptidases/metabolismo , Células Cultivadas , Córtex Cerebral/citologia , Inibidores Enzimáticos/farmacologia , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Humanos , Imunoprecipitação/métodos , Peroxidação de Lipídeos/genética , Camundongos , Camundongos Transgênicos , Neurônios/efeitos dos fármacos , Fragmentos de Peptídeos/metabolismo , Presenilina-2/deficiência
15.
J Neurochem ; 119(5): 945-56, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21910732

RESUMO

Nectins play an important role in forming various intercellular junctions including synapses. This role is regulated by several secretases present at intercellular junctions. We have investigated presenilin (PS)-dependent secretase-mediated processing of nectins in PS1 KO cells and primary hippocampal neurons. The loss of PS1/γ-secretase activity delayed the processing of nectin-1 and caused the accumulation of its full-length and C-terminal fragments. Over-expression of PS2 in PS1 KO cells compensated for the loss of PS1, suggesting that PS2 also has the ability to regulate nectin-1 processing. In mouse brain slices, a pronounced increase in levels of 30 and 24 kDa C-terminal fragments in response to chemical long-term potentiation was observed. The mouse brain synaptosomal fractionation study indicated that nectin-1 localized to post-synaptic and preferentially pre-synaptic membranes and that shedding occurs in both compartments. These data suggest that nectin-1 shedding and PS-dependent intramembrane cleavage occur at synapses, and is a regulated event during conditions of synaptic plasticity in the brain. Point mutation analysis identified several residues within the transmembrane domain that play a critical role in the positioning of cleavage sites by ectodomain sheddases. Nectin-3, which forms hetero-trans-dimers with nectin-1, also undergoes intramembrane cleavage mediated by PS1/γ-secretase, suggesting that PS1/γ-secreatse activity regulates synapse formation and remodeling by nectin processing.


Assuntos
Secretases da Proteína Precursora do Amiloide/fisiologia , Moléculas de Adesão Celular/metabolismo , Presenilina-1/fisiologia , Presenilina-2/metabolismo , Secretases da Proteína Precursora do Amiloide/deficiência , Secretases da Proteína Precursora do Amiloide/genética , Animais , Células COS , Chlorocebus aethiops , Células HEK293 , Hipocampo/enzimologia , Hipocampo/metabolismo , Hipocampo/fisiologia , Humanos , Camundongos , Camundongos Knockout , Nectinas , Técnicas de Cultura de Órgãos , Mutação Puntual/genética , Presenilina-1/deficiência , Presenilina-1/genética , Presenilina-2/deficiência , Presenilina-2/genética , Processamento de Proteína Pós-Traducional/genética , Ratos , Ratos Sprague-Dawley
16.
J Neurosci ; 31(8): 2781-91, 2011 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-21414900

RESUMO

Presenilins are ubiquitous, intramembrane proteins that function in Alzheimer's disease (AD) as the catalytic component of the γ-secretase complex. Familial AD mutations in presenilin are known to exacerbate lysosomal pathology. Hence, we sought to elucidate the function endogenous, wild-type presenilins play in autophagy-mediated protein degradation. We report the finding that genetic deletion or knockdown of presenilins alters many autophagy-related proteins demonstrating a buildup of autophagosomes, indicative of dysfunction in the system. Presenilin-deficient cells inefficiently clear long-lived proteins and fail to build up autophagosomes when challenged with lysosomal inhibitors. Our studies further show that γ-secretase inhibitors do not adversely impact autophagy, indicating that the role of presenilins in autophagy is independent of γ-secretase activity. Based on our findings, we conclude that endogenous, wild-type presenilins are necessary for proper protein degradation through the autophagosome-lysosome system by functioning at the lysosomal level. The role of presenilins in autophagy has many implications for its function in neurological diseases such as AD.


Assuntos
Secretases da Proteína Precursora do Amiloide/fisiologia , Autofagia/genética , Lisossomos/metabolismo , Presenilina-1/fisiologia , Presenilina-2/fisiologia , Doença de Alzheimer/enzimologia , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Animais , Linhagem Celular Tumoral , Células Cultivadas , Lisossomos/enzimologia , Lisossomos/patologia , Camundongos , Neurônios/enzimologia , Neurônios/metabolismo , Neurônios/patologia , Presenilina-1/deficiência , Presenilina-2/deficiência , Proteínas/metabolismo
17.
Mol Cell Biochem ; 347(1-2): 13-20, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20953898

RESUMO

We used forebrain-specific conditional presenilin 1 (PS1) and presenilin 2 (PS2) double knockout mice (dKO mice), which exhibit neurodegenerative disease-like symptoms, including inflammation of the brain and periphery, to investigate whether periodontal and salivary tissues display alterations. Mandibles were dissected for alveolar bone height analysis. Maxillae were fixed and decalcified for histological observation and osteoclast detection. Submandibular glands were fixed for histological observation. The submandibular gland and the gingiva of the mandibular incisor teeth were used to assay inflammatory mediators. At 9 months, the number of osteoclasts had significantly increased in the periodontal ligament and the periodontal tissues exhibited obvious histomorphological abnormalities in the dKO mice compared to the control mice at the same age. Alveolar bone loss in dKO mice increased with age. The salivary tissues in dKO mice exhibited obvious age-dependent histomorphological abnormalities. The levels of the inflammatory mediators IL-1ß, TNF-α, and GM-CSF in the submandibular gland and gingiva also increased in an age-dependent manner. These findings suggest that inflammation in the dKO brain could expand to the periphery, including the oral tissue, which could ultimately induce abnormalities in the periodontal and salivary tissues.


Assuntos
Periodonto/anormalidades , Presenilina-1/deficiência , Presenilina-2/deficiência , Glândulas Salivares/anormalidades , Animais , Reabsorção Óssea/metabolismo , Reabsorção Óssea/patologia , Contagem de Células , Ensaio de Imunoadsorção Enzimática , Gengiva/metabolismo , Gengiva/patologia , Mediadores da Inflamação/metabolismo , Camundongos , Camundongos Knockout , Dente Molar/metabolismo , Dente Molar/patologia , Osteoclastos/metabolismo , Osteoclastos/patologia , Ligamento Periodontal/metabolismo , Ligamento Periodontal/patologia , Periodonto/metabolismo , Periodonto/patologia , Presenilina-1/metabolismo , Presenilina-2/metabolismo , Glândulas Salivares/metabolismo , Glândulas Salivares/patologia , Glândula Submandibular/metabolismo , Glândula Submandibular/patologia
18.
J Neurochem ; 113(1): 262-74, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20089128

RESUMO

The amyloid precursor protein is a ubiquitously expressed transmembrane protein that has been long implicated in the pathogenesis of Alzheimer's disease but its normal biological function has remained elusive despite extensive effort. We have previously reported the identification of Notch2 as an amyloid precursor protein interacting protein in E18 rat neurons. Here, we sought to reveal the physiologic consequences of this interaction. We report a functional relationship between amyloid precursor protein and Notch1, which does not affect Delta ligand binding. First, we observed interactions between the amyloid precursor protein and Notch in mouse embryonic stem cells lacking both presenilin 1 and presenilin 2, the active proteolytic components of the gamma-secretase complex, suggesting that these two transmembrane proteins can interact in the absence of presenilin. Next, we demonstrated that the amyloid precursor protein affects Notch signaling by using Notch-dependent luciferase assays in two cell lines, the human embryonic kidney 293 and the monkey kidney, COS7. We found that the amyloid precursor protein exerts opposing effects on Notch signaling in human embryonic kidney 293 vs. COS7 cells. Finally, we show that more Notch Intracellular Domain is found in the nucleus in the presence of exogenous amyloid precursor protein or its intracellular domain, suggesting the mechanism by which the amyloid precursor protein affects Notch signaling in certain cells. Our results provide evidence of potentially important communications between the amyloid precursor protein and Notch.


Assuntos
Precursor de Proteína beta-Amiloide/fisiologia , Receptor Notch1/metabolismo , Transdução de Sinais/fisiologia , Secretases da Proteína Precursora do Amiloide/genética , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Linhagem Celular Transformada , Células Cultivadas , Chlorocebus aethiops , Proteínas Contráteis/genética , Embrião de Mamíferos , Filaminas , Citometria de Fluxo/métodos , Regulação da Expressão Gênica/genética , Humanos , Proteínas Luminescentes/genética , Camundongos , Proteínas dos Microfilamentos/genética , Presenilina-1/deficiência , Presenilina-2/deficiência , Ligação Proteica/efeitos dos fármacos , Proteínas/genética , Células-Tronco , Transfecção/métodos
19.
J Comp Neurol ; 517(4): 512-23, 2009 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-19795494

RESUMO

Greater than 90% of familial Alzheimer's disease (AD) is linked to mutations of presenilin (PS), and the loss of PS function altogether within mouse brains by conditional double knockout of the PS 1 and 2 genes (PS-cDKO) leads to age-dependent emergence of AD phenotypes, including neurodegeneration and reduced synaptic plasticity in the hippocampal CA1. The goal of our study was to identify the ultrastructural and molecular changes at synapses in the hippocampal CA1 of this PS-cDKO mouse model of AD. We examined the asymmetric (excitatory) synapses formed on apical dendrites of CA1 pyramidal neurons at 2 months postnatal, an age when AD-like symptoms emerge but brain morphology, as assessed by light microscopy, is still normal. Our quantitative electron microscopic analyses confirm that PS-cDKO hippocampi at 2 months postnatal do not yet exhibit synapse losses or spine size alterations. However, immunocytochemistry reveals that the same region exhibits a 28% increase in the proportion of spines labeled for the NR2A subunits of NMDA receptors (NMDAR), with a 31% increase specifically at postsynaptic densities and a concomitant reduction of these subunits at nonsynaptic sites within spine heads. In contrast, no change in levels or the distribution pattern of NR2B subunit levels were detected within spine heads. Presynaptically, NR2A levels are elevated at axo-spinous junctions and these may contribute to the timing-dependent, long-term depression. These observations point to an early-onset trapping of NMDAR at synapses that are subtle but may underlie the reduced synaptic plasticity at 2 months of age and excitotoxicity at later stages.


Assuntos
Região CA1 Hipocampal/citologia , Regulação da Expressão Gênica/genética , Presenilina-1/deficiência , Presenilina-2/deficiência , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapses/metabolismo , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Dendritos/metabolismo , Camundongos , Camundongos Knockout , Microscopia Imunoeletrônica/métodos , Modelos Biológicos , Terminações Pré-Sinápticas/metabolismo , Terminações Pré-Sinápticas/ultraestrutura , Receptores de N-Metil-D-Aspartato/genética , Sinapses/ultraestrutura
20.
Neurosci Bull ; 25(3): 131-7, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19448687

RESUMO

OBJECTIVE: This report aims to describe the oxidative damage profile in brain of presenilin1 and presenilin2 conditional double knockout mice (dKO) at both early and late age stages, and to discuss the correlation between oxidative stress and the Alzheimer-like phenotypes of dKO mice. METHODS: The protein level of Abeta(42) in dKO cortex and free 8-OHdG level in urine were measured by ELISA. Thiobarbituric acid method and spectrophotometric DNPH assay were used to determine the lipid peroxidation and protein oxidation in cortex, respectively. SOD and GSH-PX activities were assessed by SOD Assay Kit-WST and GSH-PX assay kit, separately. RESULTS: Significant decrease of Abeta(42) was verified in dKO cortex at 6 months as compared to control mice. Although lipid peroxidation (assessed by MDA) was increased only in dKO cortex at 3 months and protein oxidation (assessed by carbonyl groups) was basically unchanged in dKO cortex, ELISA analysis revealed that free 8-OHdG, which was an indicator of DNA lesion, was significantly decreased in urine of dKO mice from 3 months to 12 months. Activities of SOD and GSH-PX in dKO and control cortices showed no statistical difference except a significant increase of GSH-PX activity in dKO mice at 9 months. CONCLUSION: Oxidative damage, especially DNA lesion, was correlated with the neurodegenerative symptoms that appeared in dKO mice without the deposition of Abeta(42). Triggers of oxidative damage could be the inflammatory mediators released by activated microglia and astrocytes.


Assuntos
Doença de Alzheimer/fisiopatologia , Camundongos Knockout/fisiologia , Estresse Oxidativo/fisiologia , Presenilina-1/deficiência , Presenilina-2/deficiência , 8-Hidroxi-2'-Desoxiguanosina , Fatores Etários , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/urina , Animais , Desoxiguanosina/análogos & derivados , Desoxiguanosina/urina , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática/métodos , Glutationa/metabolismo , Hidrazinas/metabolismo , Peroxidação de Lipídeos/genética , Malondialdeído/metabolismo , Camundongos , Camundongos Endogâmicos CBA , Oxirredução , Fragmentos de Peptídeos/urina , Espectrofotometria Atômica/métodos , Superóxido Dismutase/metabolismo
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