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Acidosis, a common feature of cerebral ischaemia and hypoxia, plays a key role in these pathological processes by aggravating the ischaemic and hypoxic injuries. To explore the mechanisms, in this research, we cultured primary neurons in an acidic environment (potential of hydrogen [pH]6.2, 24 hours) to mimic the acidosis. By proteomic analysis, 69 differentially expressed proteins in the acidic neurons were found, mainly related to stress and cell death, synaptic plasticity and gene transcription. And, the acidotic neurons developed obvious alterations including increased neuronal death, reduced dendritic length and complexity, reduced synaptic proteins, tau hyperphosphorylation, endoplasmic reticulum (ER) stress activation, abnormal lysosome-related signals, imbalanced oxidative stress/anti-oxidative stress and decreased Golgi matrix proteins. Then, melatonin (1 × 10-4 mol/L) was used to pre-treat the cultured primary neurons before acidic treatment (pH6.2). The results showed that melatonin partially reversed the acidosis-induced neuronal death, abnormal dendritic complexity, reductions of synaptic proteins, tau hyperphosphorylation and imbalance of kinase/phosphatase. In addition, acidosis related the activations of glycogen synthase kinase-3ß and nuclear factor-κB signals, ER stress and Golgi stress, and the abnormal autophagy-lysosome signals were completely reversed by melatonin. These data indicate that melatonin is beneficial for neurons against acidosis-induced injuries.
Assuntos
Acidose/patologia , Melatonina/farmacologia , Neurônios/patologia , Substâncias Protetoras/farmacologia , Animais , Apoptose/efeitos dos fármacos , Dendritos/efeitos dos fármacos , Dendritos/metabolismo , Espaço Extracelular/metabolismo , Feminino , Concentração de Íons de Hidrogênio , Neurônios/efeitos dos fármacos , Organelas/efeitos dos fármacos , Organelas/metabolismo , Fosforilação/efeitos dos fármacos , Ratos Sprague-Dawley , Estresse Fisiológico/efeitos dos fármacos , Sinapses/efeitos dos fármacos , Sinapses/patologia , Proteínas tau/metabolismoRESUMO
Background: Hyperhomocysteinemia is an independent risk factor for dementia, including Alzheimer's disease. Lowering homocysteine levels with folic acid treatment with or without vitamin B12 has shown few clinical benefits on cognition. Methods: To verify the effect of emodin, a naturally active compound from Rheum officinale, on hyperhomocysteinemia-induced dementia, rats were treated with homocysteine injection (HCY, 400 µg/kg/d, 2 weeks) via vena caudalis. Afterwards, HCY rats with cognitive deficits were administered intragastric emodin at different concentrations for 2 weeks: 0 (HCY-E0), 20 (HCY-E20), 40 (HCY-E40), and 80 mg/kg/d (HCY-E80). Results: ß-Amyloid overproduction, tau hyperphosphorylation, and losses of neuron and synaptic proteins were detected in the hippocampi of HCY-E0 rats with cognitive deficits. HCY-E40 and HCY-E80 rats had better behavioral performance. Although it did not reduce the plasma homocysteine level, emodin (especially 80 mg/kg/d) reduced the levels of ß-amyloid and tau phosphorylation, decreased the levels of ß-site amyloid precursor protein-cleaving enzyme 1, and improved the activity of protein phosphatase 2A. In the hippocampi of HCY-E40 and HCY-E80 rats, the neuron numbers, levels of synaptic proteins, and phosphorylation of the cAMP responsive element-binding protein at Ser133 were increased. In addition, depressed microglial activation and reduced levels of 5-lipoxygenase, interleukin-6, and tumor necrosis factor α were also observed. Lastly, hyperhomocysteinemia-induced microangiopathic alterations, oxidative stress, and elevated DNA methyltransferases 1 and 3ß were rescued by emodin. Conclusions: Emodin represents a novel potential candidate agent for hyperhomocysteinemia-induced dementia and Alzheimer's disease-like features.
Assuntos
Demência/tratamento farmacológico , Demência/etiologia , Emodina/farmacologia , Hiper-Homocisteinemia/complicações , Hiper-Homocisteinemia/tratamento farmacológico , Nootrópicos/farmacologia , Peptídeos beta-Amiloides/metabolismo , Animais , Transtornos Cognitivos/tratamento farmacológico , Transtornos Cognitivos/etiologia , Transtornos Cognitivos/metabolismo , Transtornos Cognitivos/patologia , Metilação de DNA/efeitos dos fármacos , Metilação de DNA/fisiologia , Demência/metabolismo , Demência/patologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/patologia , Hiper-Homocisteinemia/metabolismo , Hiper-Homocisteinemia/patologia , Masculino , Microglia/efeitos dos fármacos , Microglia/metabolismo , Microglia/patologia , Microvasos/efeitos dos fármacos , Microvasos/metabolismo , Microvasos/patologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/fisiologia , Distribuição Aleatória , Ratos Sprague-Dawley , Proteínas tau/metabolismoRESUMO
Endoplasmic reticulum (ER) stress is involved in Alzheimer's disease (AD), but the mechanism is not fully understood. Here, we injected tunicamycin (TM), a recognized ER stress inducer, into the brain ventricle of Sprague-Dawley (SD) rats to induce the unfolded protein response (UPR), demonstrated by the enhanced phosphorylation of pancreatic ER kinase (PERK), inositol-requiring enzyme-1 (IRE-1) and activating transcription factor-6 (ATF-6). We observed that UPR induced spatial memory deficits and impairments of synaptic plasticity in the rats. After TM treatment, GSK-3ß was activated and phosphorylation of cAMP response element binding protein at Ser129 (pS129-CREB) was increased with an increased nuclear co-localization of pY126-GSK-3ß and pS129-CREB. Simultaneous inhibition of GSK-3ß by hippocampal infusion of SB216763 (SB) attenuated TM-induced UPR and spatial memory impairment with restoration of pS129-CREB and synaptic plasticity. We concluded that UPR induces AD-like spatial memory deficits with mechanisms involving GSK-3ß/pS129-CREB pathway.
Assuntos
Encéfalo/patologia , Estresse do Retículo Endoplasmático/fisiologia , Quinase 3 da Glicogênio Sintase/metabolismo , Memória Espacial/fisiologia , Fator 6 Ativador da Transcrição/metabolismo , Doença de Alzheimer/patologia , Animais , Encéfalo/efeitos dos fármacos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Modelos Animais de Doenças , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Masculino , Proteínas de Membrana/metabolismo , Fosforilação/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Ratos Sprague-Dawley , Serina/metabolismo , Memória Espacial/efeitos dos fármacos , Tunicamicina/toxicidade , Tirosina/metabolismo , Resposta a Proteínas não Dobradas/efeitos dos fármacos , eIF-2 Quinase/metabolismoRESUMO
Menopause, a risk factor for brain dysfunction in women, is characterized by neuropsychological symptoms including depression and dementia, which are closely related to alterations in different brain regions after menopause. However, little is known about the variability in pathophysiologic changes associated with menopause in the brain. Here, we observed that menopause in rats induced by bilateral ovariectomy (OVX) showed depressive and dementia-related behaviors along with neuronal loss in the prefrontal cortex (PFC), hippocampus (HIP), hypothalamus (HYP), and amygdala (AMY) by Nissl staining. Meanwhile, by immunohistochemical staining, increased microglia in the HIP and AMY and increased astrocytes in the PFC, HYP, and AMY were shown. Using quantitative proteomics, we identified 146 differentially expressed proteins in the brains of OVX rats, for example, 20 in the PFC, 41 in the HIP, 17 in the HYP, and 79 in the AMY, and performed further detection by western blotting. A link between neuronal loss and apoptosis was suggested, as evidenced by increases in adenylate kinase 2 (AK2), B-cell lymphoma 2 associated X (Bax), cleaved caspase 3, and phosphorylated p53 and decreases in Huntingtin-interacting protein K, hexokinase, and phosphorylated B-cell lymphoma 2 (Bcl-2), and apoptosis might be triggered by endoplasmic reticulum stress (probed by increased glucose-regulated protein 78 (GRP78), cleaved caspase 12, phosphorylated protein kinase R (PKR)-like endoplasmic reticulum kinase, inositol-requiring enzyme-1 and activating transcription factor 6), and mitochondrial dysfunction (probed by increased cytochrome c and cleaved caspase 3 and decreased sideroflexin-1 (SFXN1) and NADH dehydrogenase (ubiquinone) 1 α subcomplex 11 (NDUFA11)). Activation of autophagy was also indicated by increased autophagy-related 7, γ-aminobutyric acid (GABA) receptor-associated protein-like 2, and oxysterol-binding protein-related protein 1 and confirmed by increased microtubule-associated protein light chain 3 (LC3II/I), autophagy-related 5, and Beclin1 in the HIP and AMY. In the AMY, which is important in emotion, higher GABA transporter 3 and lower vesicular glutamate transporter 1 levels indicated an imbalance between excitatory and inhibitory neurotransmission, and the increased calretinin and decreased calbindin levels suggested an adjustment of GABAergic transmission after OVX. In addition, cytoskeletal abnormalities including tau hyperphosphorylation, dysregulated Ca²+ signals, and glutamic synaptic impairments were observed in the brains of OVX rats. Collectively, our study showed the changes in different brain regions related to depression and dementia during menopause.
Assuntos
Encéfalo/metabolismo , Demência/etiologia , Demência/patologia , Depressão/etiologia , Depressão/patologia , Ovariectomia/efeitos adversos , Animais , Autofagia/fisiologia , Proteínas de Ligação ao Cálcio/metabolismo , Citoesqueleto/patologia , Modelos Animais de Doenças , Estradiol/sangue , Feminino , Regulação da Expressão Gênica/fisiologia , Proteínas de Choque Térmico/metabolismo , Proteínas de Membrana/metabolismo , Proteínas dos Microfilamentos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteômica , Ratos , Ratos Sprague-Dawley , Transdução de Sinais/fisiologia , Fatores de TempoRESUMO
With the expansion of global energy problems and the deepening of research on oxygen reduction reaction (ORR) in alkaline media, the development of low cost and high electrocatalytic performance catalysts has become a research hotspot. In this study, a hexagonal Pd-C-MnOOH composite catalyst was prepared by using the triblock copolymer P123 as the reducing agent and protective agent, sucrose as the carbon source and self-made MnOOH as the carrier under hydrothermal conditions. When the Pd load is 20% and the C/MnOOH ratio is 1 : 1, the 20% Pd-C-MnOOH-1 : 1 catalyst obtained by the one-step method has the highest ORR activity and stability in the alkaline system. At 1600 rpm, the limiting diffusion current density and half-wave potential of the 20% Pd-C-MnOOH-1 : 1 electrocatalyst are -4.78 mA cm-2 and 0.84 V, respectively, which are better than those of the commercial 20%Pd/C catalyst. According to the Koutecky-Levich (K-L) equation and the linear fitting results, the electron transfer number of the 20%Pd-C-MnOOH-1 : 1 electrocatalyst for the oxygen reduction reaction is 3.8, which is similar to that of a 4-electron process. After 1000 cycles, the limiting diffusion current density of the 20%Pd-C-MnOOH-1 : 1 catalyst is -4.61 mA cm-2, which only decreases by 3.7%, indicating that the 20%Pd-C-MnOOH-1 : 1 catalyst has good stability. The reason for the improvement of the ORR performance of the Pd-C-MnOOH composite catalyst is the improvement of the conductivity of the carbon layer formed by original carbonization, the regular hexagonal highly active Pd particles and the synergistic catalytic effect between Pd and MnOOH. The method of introducing triblock copolymers in the synthesis of oxides and metal-oxide composite catalysts is expected to be extended to other electrocatalysis fields.
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Alzheimer's disease (AD) is the most common cause of neurodegenerative dementia and one of the top medical concerns worldwide. Currently, the approved drugs to treat AD are effective only in treating the symptoms, but do not cure or prevent AD. Although the exact causes of AD are not understood, it is recognized that tau aggregation in neurons plays a key role. Chuanxiong Rhizoma (CR) has been widely reported as effective for brain diseases such as dementia. Thus, we explored the protections of CR in AD by a tau pathogenesis-based network pharmacology approach. According to ultra-HPLC with triple quadrupole mass spectrometry data and Lipinski's rule of five, 18 bioactive phytochemicals of CR were screened out. They were shown corresponding to 127 tau pathogenesis-related targets, among which VEGFA, IL1B, CTNNB1, JUN, ESR1, STAT3, APP, BCL2L1, PTGS2, and PPARG were identified as the core ones. We further analyzed the specific actions of CR-active phytochemicals on tau pathogenesis from the aspects of tau aggregation and tau-mediated toxicities. It was shown that neocnidilide, ferulic acid, coniferyl ferulate, levistilide A, Z-ligustilide, butylidenephthalide, and caffeic acid can be effective in reversing tau hyperphosphorylation. Neocnidilide, senkyunolide A, butylphthalide, butylidenephthalide, Z-ligustilide, and L-tryptophan may be effective in promoting lysosome-associated degradation of tau, and levistilide A, neocnidilide, ferulic acid, L-tryptophan, senkyunolide A, Z-ligustilide, and butylidenephthalide may antagonize tau-mediated impairments of intracellular transport, axon and synaptic damages, and neuron death (especially apoptosis). The present study suggests that acting on tau aggregation and tau-mediated toxicities is part of the therapeutic mechanism of CR against AD.
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Whether amino acids act on cellular insulin signaling remains unclear, given that increased circulating amino acid levels are associated with the onset of type 2 diabetes (T2D). Here, we report that phenylalanine modifies insulin receptor beta (IRß) and inactivates insulin signaling and glucose uptake. Mice fed phenylalanine-rich chow or phenylalanine-producing aspartame or overexpressing human phenylalanyl-tRNA synthetase (hFARS) develop insulin resistance and T2D symptoms. Mechanistically, FARS phenylalanylate lysine 1057/1079 of IRß (F-K1057/1079), inactivating IRß and preventing insulin from promoting glucose uptake by cells. SIRT1 reverse F-K1057/1079 and counteract the insulin-inactivating effects of hFARS and phenylalanine. F-K1057/1079 and SIRT1 levels in white blood cells from T2D patients are positively and negatively correlated with T2D onset, respectively. Blocking F-K1057/1079 with phenylalaninol sensitizes insulin signaling and relieves T2D symptoms in hFARS-transgenic and db/db mice. These findings shed light on the activation of insulin signaling and T2D progression through inhibition of phenylalanylation.
Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Animais , Diabetes Mellitus Tipo 2/metabolismo , Glucose/metabolismo , Humanos , Insulina , Resistência à Insulina/fisiologia , Camundongos , Fenilalanina , Sirtuína 1/genéticaRESUMO
Glycogen synthase kinase-3ß (GSK-3ß) plays a crucial role in memory deficits and tau hyperphosphorylation as seen in Alzheimer's disease, the most common dementia in the aged population. We reported that ventricular co-injection of wortmannin and GF-109203X (WT/GFX) can induce tau hyperphosophorylation and memory impairment of rats through activation of GSK-3 [Liu S. J., Zhang A. H., Li H. L., Wang Q., Deng H. M., Netzer W. J., Xu H. X. and Wang J. Z. (2003) J. Neurochem. 87, 1333]. In the present study, we found that feeding the rats with Acetyl-L-Carnitine (ALCAR, 50 mg/day·rat, per os) for 2 weeks rescued the WT/GFX-induced spatial memory retention impairment of the rats by antagonizing GSK-3ß activation independent of Akt, PKCζ and Erk1/2. We also found that ALCAR arrested microtubule-associated protein tau hyperphosphorylation at multiple Alzheimer's disease sites in vivo and in vitro. Moreover, ALCAR enhanced the expression of several memory-associated proteins including c-Fos, synapsin I in rat hippocampus. These results suggest that ALCAR could ameliorate WT/GFX-induced spatial memory deficits through inhibition tau hyperphosphorylation and modulation of memory-associated proteins.
Assuntos
Acetilcarnitina/uso terapêutico , Inibidores Enzimáticos/efeitos adversos , Transtornos da Memória/induzido quimicamente , Transtornos da Memória/tratamento farmacológico , Fosfatidilinositol 3-Quinases/metabolismo , Proteína Quinase C/metabolismo , Complexo Vitamínico B/uso terapêutico , Animais , Comportamento Animal/efeitos dos fármacos , Células Cultivadas , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Hipocampo/citologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Humanos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Camundongos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Inibidores de Fosfoinositídeo-3 Quinase , Fosforilação/efeitos dos fármacos , Proteína Quinase C/antagonistas & inibidores , Ratos , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Sincalida/metabolismo , Proteínas tau/metabolismoRESUMO
One-dimensional CoPt nanorods were obtained through the galvanic displacement reaction and chemical reduction. The average diameter of the nanorods was measured to be about 166.3 nm and the length was mostly between 1.0 and 5.0 microm obtained from the scanning electron microscopy (SEM) measurement. The IR optical properties of the CoPt nanorods and bulk Pt were investigated by in situ FTIR reflection spectroscopy employing CO adsorption as probe reaction at the solid/gas interface. The results of in situ FTIR indicated that bulk Pt shows a normal IR optical property and the CoPt nanorods display abnormal infrared effects (AIREs). The authors can obtain the same results whether the CoPt nanorods were loaded on glassy carbon (GC) or Au substrates. These results demonstrated that the AIREs were generated mainly by CoPt nanorods and the influence of the substrate materials can be neglected. The study confirmed that one-dimensional CoPt nanorods show AIREs, and throw a new sense to comprehend the anomalous IR properties observed on low-dimensional nanomaterials.
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Presently, the treatment options for ischemic stroke (IS) are limited due to the complicated pathological process of the disease. Chuanxiong Rhizome (CR), also known as Conioselinum anthriscoides "Chuanxiong" (rhizome), is the most widely used traditional Chinese medicine for treating stroke. This study aimed to uncover the key phytochemicals and biological functions of CR against IS through a network pharmacology approach combining with IS pathophysiology analysis. We employed permanent unilateral common carotid artery ligation to construct a mouse model of global cerebral ischemia and found that cerebral ischemia injuries were improved after 7 days of gavage treatment of CR (1,300 mg/kg/day). CR exerts protective effects on neurons mainly by acting on targets related to synaptic structure, synaptic function, neuronal survival and neuronal growth. A total of 18 phytochemicals from CR based on UHPLC-MS/MS that corresponded to 85 anti-IS targets. Coniferyl ferulate, neocnidilide and ferulic acid were identified as the key phytochemicals of CR against IS. Its brain protective effects involve anti-inflammatory, anti-oxidative stress, and anti-cell death activities and improves blood circulation. Additionally, the two most important synergistic effects of CR phytochemicals in treating IS are prevention of infection and regulation of blood pressure. In brain samples of Sham mice, L-tryptophan and vanillin were detected, while L-tryptophan, gallic acid, vanillin and cryptochlorogenic acid were detected in IS mice by UHPLC-MS/MS. Our findings provide a pathophysiology relevant pharmacological basis for further researches on IS therapeutic drugs.
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A perfect PtCu nanocube with partial hollow structure was prepared by hydrothermal reaction and its electrocatalytic methanol oxidation reaction (MOR) was studied. The appropriate concentration of shape-control additives KI and triblock pluronic copolymers, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO19-PPO69-PEO19) (P123) play crucial roles in the final product morphology. The PtCu nanocubes can be perfectly in situ immobilizedonto graphene under the action of P123 while the structure and cubic morphologyremain unchanged. The electrochemical tests suggest that the obtained PtCu nanocube (PtCu-NCb) exhibits better MOR activity and stability than PtCu hexagon nanosheet (PtCu-NSt), PtCu nanoellipsoid (PtCu-NEs) and commercial Pt/C in alkaline medium. When in situ immobilized onto graphene, the MOR catalytic activity and stability of PtCu cubes are further improved. The markedly enhanced electrocatalytic activity and durability maybe attributed to the special cubic morphology with partial hollow structure enclosed by highly efficient facet and the probably the synergistic effect of PtCu and intermediate state CuI decorated on the surface and graphene.
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Amyloid-ß (Aß) accumulating is considered as a causative factor for formation of senile plaque in Alzheimer's disease (AD), but its mechanism is still elusive. The Nicotinamide mononucleotide adenylyltransferase 2 (Nmnat2), a key redox cofactor for energy metabolism, is reduced in AD. Accumulative evidence has shown that the decrease of α-secretase activity, a disintegrin and metalloprotease domain 10 (ADAM10), is responsible for the increase of Aß productions in AD patient's brain. Here, we observe that the activity of α-secretase ADAM10 and levels of Nmnat2 are significantly decreased, meanwhile there is a simultaneous elevation of Aß in Tg2576 mice. Over-expression of Nmnat2 increases the mRNA expression of α-secretase ADAM10 and its activity and inhibits Aß production in N2a/APPswe cells, which can be abolished by Compound C, an AMPK antagonist, suggesting that AMPK is involved in over-expression of Nmnat2 against Aß production. The further assays demonstrate that Nmnat2 activates AMPK by up-regulating the ratio of NAD+/NADH, moreover AMPK agonist AICAR can also increase ADAM10 activity and reduces Aß1-40/1-42. Taken together, Nmnat2 suppresses Aß production and up-regulates ADAM10 in AMPK activity-dependent manner, suggesting that Nmnat2 may serve as a new potential target in arresting AD.
Assuntos
Proteína ADAM10 , Proteínas Quinases Ativadas por AMP , Secretases da Proteína Precursora do Amiloide , Amiloide , Proteínas de Membrana , Nicotinamida-Nucleotídeo Adenililtransferase , Proteína ADAM10/genética , Proteína ADAM10/metabolismo , Proteínas Quinases Ativadas por AMP/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Amiloide/genética , Amiloide/metabolismo , Secretases da Proteína Precursora do Amiloide/genética , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Linhagem Celular , Humanos , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Nicotinamida-Nucleotídeo Adenililtransferase/genética , Nicotinamida-Nucleotídeo Adenililtransferase/metabolismo , Regulação para Cima/genéticaRESUMO
CoPt nanoparticles were prepared by galvanic displacement reaction, followed by a chemical reduction. The CoPt nanoparticles were spherical and the average diameter was about 33 nm obtained from the results of transmission electron microscopy (TEM), high resolution TEM and scanning electron microscopy (SEM). The results of powder X-ray diffration (XRD), energy dispersed X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) demonstrated that the surface of the product was mostly consist of Pt nanoparticles. An ordered monolayer film of CoPt nanoparticles on Si wafer was obtained by a Liquid/Liquid interface technique. In situ FTIR transmission spectral study indicates that the ordered self-assembled monolayer film of the CoPt nanoparticles shows Fano-like infrared effects, while the deposited CoPt nanoparticles exhibit normal enhanced IR adsorption. The results of the present paper demonstrated that the IR optical properties are closely related to the interactions and thickness of the nanomaterials and significant to understand the anomalous IR properties of nanometer materials.
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Alzheimer's disease (AD) is the most common neurodegenerative disease, but its underlying mechanism is still unclear and the identities of drugs for AD also lack. Tau acetylation has become potentially important post-translational modification of tau. Levels of tau acetylation are significantly enhanced in AD patients and transgenic mouse models of AD, but the underlying mechanism and roles of tau hyperacetylation in AD onset maintain elusive. In the current study, we found that tau acetylation is obviously enhanced and the activities of AMP-activated protein kinase (AMPK) and sirtuin1 (Sirt1) are significantly decreased in APP/PS1 and streptozotocin (STZ) mice and high glucose (HG)-treated cells. Moreover, we demonstrated that activation of AMPK reduces the level of tau acetylation and ameliorates memory impairment, and its mechanism is associated with activation of Sirt1. Taken together, AMPK might be a crucial upstream molecular to regulate acetylation of tau and become a new target for AD therapy in the future.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Transtornos da Memória/metabolismo , Sirtuína 1/metabolismo , Proteínas tau/metabolismo , Acetilação , Peptídeos beta-Amiloides/metabolismo , Animais , Regulação para Baixo , Células HEK293 , Hipocampo/metabolismo , Hipocampo/patologia , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fosforilação , Fosfotreonina/metabolismo , Presenilina-1/metabolismo , Estreptozocina , Regulação para CimaRESUMO
The studies have shown that 5'-adenosine monophosphate (AMP)-activated protein kinase (AMPK) is involved in Alzheimer's disease (AD) pathology, but the effects of AMPK on AD-like Tau abnormal phosphorylation and its underlying mechanism remains unclear. Herein, we found that the mRNA expression and activity of AMPK are significantly decreased in the brains of the aging C57 mice and 3 × Tg AD mice when compared with their respective control. Moreover, when downregulation of AMPK with AAV-siAMPK-eGFP in the hippocampus CA3 of 3-month-old C57 mice, the mice display AD-like Tau hyperphosphorylation, fear memory impairment, and glycogen synthase kinase-3ß (GSK3ß) activity increased. On the other hand, there are also AD-like Tau hyperphosphorylation, impairment of fear memory, and AMPK activity decreased in streptozotocin (STZ) mice. Interestingly, AMPK overexpression could efficiently rescue AD-like Tau phosphorylation and brain impairment in STZ mice. Moreover, the activity of GSK3ß and the level of Tau phosphorylation (Ser396 and Thr231 sites) were significantly decreased in HEK293 Tau cells transfected by AMPK plasmid or treated with agonists salicylate (SS), but GSK3ß agonists Wortmannin (Wort) could ablate AMPK-mediated Tau dephosphorylation. Taken together, the study indicated that AMPK reduces Tau phosphorylation and improves brain function and inhibits GSK3ß in AD-like model. These findings proved that AMPK might be a new target for AD in the future.
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Proteínas Quinases Ativadas por AMP/metabolismo , Doença de Alzheimer/patologia , Transtornos da Memória/metabolismo , Proteínas tau/metabolismo , Envelhecimento/patologia , Doença de Alzheimer/metabolismo , Animais , Hipocampo/metabolismo , Hipocampo/patologia , Memória/efeitos dos fármacos , Transtornos da Memória/patologia , Camundongos Endogâmicos C57BL , Fosforilação/efeitos dos fármacosRESUMO
Hollow CoPt chainlike nanomaterials were synthesized by a galvanic displacement reaction. The morphology, structure, and composition of the nanomaterials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and electron dispersive X-ray (EDX) analysis. It has found that the hollow CoPt chainlike nanoparticles supported on glassy carbon substrate (CoPt/GC) exhibited enhanced electrocatalytic activity toward methanol oxidation in comparison with commercial Pt/C catalyst (Johnson-Matthey, 20 wt% Pt). The studies demonstrated also that the hollow CoPt chainlike nanomaterials possess a superior electrocatalytic property for CO oxidation than that of Pt/C and bulk Pt. The IR properties of the CoPt nanomaterials were investigated by in situ FTIR reflection spectroscopy employing CO adsorption as probe reaction. It has revealed that the hollow CoPt chainlike nanomaterials present abnormal infrared effects (AIREs).
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The down-regulation of protein phosphatase 2A (PP2A) activity is thought to play an important role in the formation of tau hyperphosphorylation in the Alzheimer's disease (AD) brain. Methylation of the PP2A catalytic subunit at the L309 site can potently activate PP2A for some substrates via the increasing recruitment of its regulatory subunits into the holoenzyme. Abeta is overproduced yet estrogen is deficient in the brains of the menopausal AD patients. Both Abeta and estrogen deficiency can interact with tau kinases such as protein kinase B and glycogen synthase kinase 3. In the current study, levels of demethylated (-m) PP2A (L309) were significantly increased, and methylated (+m) PP2A (L309) were significantly decreased, which corresponded with the increased tau phosphorylation at the Tau-1 and PHF-1 sites in both mouse N2a cells carrying the human APP with Swedish mutation (APPswe) and transgenic APPswe/presenilin (PS) 1 (A246E) mice. These findings were replicated in wild-type N2a cells treated with Abeta25-35, and to a relatively larger extent, in both wild-type N2a cells and APPswe treated by okadaic acid, as well as in the brains of estrogen receptor (ER) alpha-/- and ERbeta-/- mice that mimic the status of estrogen deficiency in menopausal AD patients. Together, these findings suggested that the increased demethylation of PP2A (L309) mediated by Abeta overproduction or estrogen deficiency (ERalpha-/- and ERbeta-/-) may contribute to the reduced PP2A activity observed in the AD brain, resulting in the compromised dephosphorylation of abnormally hyperphosphorylated tau.
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Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Estrogênios/deficiência , Proteína Fosfatase 2/metabolismo , Proteínas tau/metabolismo , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/genética , Doença de Alzheimer/fisiopatologia , Animais , Encéfalo/fisiopatologia , Domínio Catalítico/fisiologia , Linhagem Celular , Regulação para Baixo/fisiologia , Feminino , Humanos , Masculino , Metilação , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Pessoa de Meia-Idade , Neurônios/metabolismo , Neurônios/patologia , Fosforilação , Pós-Menopausa/metabolismo , Proteínas Metiltransferases/metabolismo , Receptores de Estrogênio/metabolismoRESUMO
This study set out to search for a link between overproduction of Abeta and p70S6 kinase (p70S6K) phosphorylation/activation. Results showed that levels of p-p70S6K at T421/S424 and T389 are significantly increased in mouse N2a neuroblastoma cells carrying human APP with Swedish mutation (APPswe), and in transgenic APPswe/PS1 (A246E) mice as compared with respective controls, corresponding to the increase of tau phosphorylation at S262. This parallel increase in p70S6K activation and tau phosphorylation could be demonstrated by treating wild-type N2a cells with Abeta25-35. Our results suggest that the Abeta deposition in senile plaques in Alzheimer disease brains might be a primary event that activates p70S6K and phosphorylates tau at S262, resulting in microtubule disruption.
Assuntos
Peptídeos beta-Amiloides/biossíntese , Proteínas Quinases S6 Ribossômicas/metabolismo , Proteínas tau/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animais , Linhagem Celular Tumoral , Ativação Enzimática , Feminino , Humanos , Imuno-Histoquímica , Camundongos , Camundongos Transgênicos , Mutação , Ácido Okadáico/farmacologia , FosforilaçãoRESUMO
A novel ginsenoside-hydrolyzing beta-glucosidase was purified from Paecilomyces Bainier sp. 229 by a combination of QSepharose FF, phenyl-Sepharose CL-4B, and CHT ceramic hydroxyapatite column chromatographies. The purified enzyme was a monomeric protein with a molecular mass estimated to be 115 kDa. The optimal enzyme activity was observed at pH 3.5 and 60oC. It was highly stable within pH 3-9 and at temperatures lower than 55oC. The enzyme was specific to beta-glucoside. The order of enzyme activities against different types of beta-glucosidic linkages was beta-(1- 6)>beta-(1-2)>beta-(1-4). The enzyme converted ginsenoside Rb1 to CK specifically and efficiently. An 84.3% amount of ginsenoside Rb1, with an initial concentration of 2 mM, was converted into CK in 24 h by the enzyme at 45 degrees and pH 3.5. The hydrolysis pathway of ginsenoside Rb1 by the enzyme was Rb1-->Rd-->F2-->CK. Five tryptic peptide fragments of the enzyme were identified by a newly developed de novo sequencing method of post-source decay (PSD) matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. By comparing the five identified peptide sequences with the NCBI database, this purified beta-glucosidase proves to be a new protein that has not been reported before.
Assuntos
Proteínas Fúngicas/metabolismo , Ginsenosídeos/metabolismo , Paecilomyces/enzimologia , beta-Glucosidase/metabolismo , Sequência de Aminoácidos , Cromatografia em Agarose , Eletroforese em Gel de Poliacrilamida , Proteínas Fúngicas/química , Concentração de Íons de Hidrogênio , Hidrólise , Dados de Sequência Molecular , Peso Molecular , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Especificidade por Substrato , Temperatura , beta-Glucosidase/químicaRESUMO
Although several studies have shown that type-2 cannabinoid receptor (CB2R) is involved in Alzheimer's disease (AD) pathology, the effects of CB2R on AD-like tau abnormal phosphorylation and its underlying mechanism remain unclear. Herein, we employed the CB2R-/- mice as the animal model to explore roles of CB2R in regulating tau phosphorylation and brain function. We found that CB2R-/- mice display AD-like tau hyperphosphorylation, hippocampus-dependent memory impairment, increase of GSK3ß activity, decrease of AMPK and Sirt1 activity and mitochondria dysfunction. Interestingly, AICAR or resveratrol (AMPK agonist) could efficiently rescue most alternations caused by solo deletion of CB2R in CB2R-/- mice. Moreover, JWH133, a selective agonist of CB2R, reduces phosphorylation of tau and GSK3ß activity in HEK293 tau cells, but the effects of JWH133 on phosphorylation of tau and GSK3ß disappeared while blocking AMPK activity with compound C or Prkaa2-RNAi. Taken together, our study indicated that deletion of CB2R induces behavior damage and AD-like pathological alternation via AMPK/GSK3ß pathway. These findings proved that CB2R/AMPK/GSK3ß pathway can be a promising new drug target for AD.