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Resveratrol (RES), a natural polyphenolic phytochemical, has been suggested as a putative anti-aging molecule for the prevention and treatment of Alzheimer's disease (AD) by the activation of sirtuin 1 (Sirt1/Sir2). In this study, we tested the effects of RES and Sirt1/Sir2 on sleep and courtship memory in a Drosophila model by overexpression of amyloid precursor protein (APP), whose duplications and mutations cause familial AD. We found a mild but significant transcriptional increase of Drosophila Sir2 (dSir2) by RES supplementation for up to 17 days in APP flies, but not for 7 days. RES and dSir2 almost completely reversed the sleep and memory deficits in APP flies. We further demonstrated that dSir2 acts as a sleep promotor in Drosophila neurons. Interestingly, RES increased sleep in the absence of dSir2 in dSir2-null mutants, and RES further enhanced sleep when dSir2 was either overexpressed or knocked down in APP flies. Finally, we showed that Aβ aggregates in APP flies were reduced by RES and dSir2, probably via inhibiting Drosophila β-secretase (dBACE). Our data suggest that RES rescues the APP-induced behavioral deficits and Aβ burden largely, but not exclusively, via dSir2.
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Animals , Alzheimer Disease/metabolism , Amyloid beta-Peptides , Amyloid beta-Protein Precursor/metabolism , Drosophila/physiology , Drosophila Proteins/metabolism , Resveratrol/pharmacology , Sirtuin 1 , SleepABSTRACT
Blood-brain barrier (BBB) strictly controls matter exchange between blood and brain, and severely limits brain penetration of systemically administered drugs, resulting in ineffective drug therapy of brain diseases. However, during the onset and progression of brain diseases, BBB alterations evolve inevitably. In this review, we focus on nanoscale brain-targeting drug delivery strategies designed based on BBB evolutions and related applications in various brain diseases including Alzheimer's disease, Parkinson's disease, epilepsy, stroke, traumatic brain injury and brain tumor. The advances on optimization of small molecules for BBB crossing and non-systemic administration routes (
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OBJECTIVE: To observe the effect of electroacupuncture (EA) intervention on learning-memory ability and the expression of senile plaques (SP), amyloid precursor protein (APP), β-secretase 1(BACE 1) and insulin degrading enzyme (IDE) in the hippocampus in APP/presenilin 1 (PS 1) double transgenic Alzheimer's disease (AD) mice, so as to reveal its mechanisms underlying improvement of AD. METHODS: A total of 18 male APP/PS 1 double transgenic AD mice were randomly divided into model, EA-2-week and EA-3-week groups (n=6 in each). The control group was consisted of 6 male wild mice. EA (2 Hz, 2 mA) was applied to "Baihui" (GV 20) and bilateral "Shenshu" (BL 23) for 15 min, once a day, with 7 days being a therapeutic course, 2 or 3 courses altogether and with an one day's interval between every two courses. The spatial learning-memory ability was assessed using Morris water maze test during 5 days' training. The immunoactivity of SP in the hippocampus tissue was detected by immunohistochemistry, and the expression levels of APP, BACE 1 and IDE in the hippocampus were analyzed by Western blot. RESULTS: Following modeling, the escape latency and path length of hidden platform tests were significantly increased (P<0.01, P<0.05), and the platform crossing time of spatial probing test significantly decreased (P<0.01) in the model group compared with the control group. After EA intervention, the escape latency on the 5th day of training, and the path length on the 4th and 5th day of training in both EA-2-week and EA-3-week groups were significantly shorter relevant to the model group (P<0.01), and those of the EA-3-week group were considerably shorter than those of the EA-2-week group in the escape latency and path length (P<0.05, P<0.01). The platform crossing times of spatial probing test were significanthy increased in both EA-2-week and EA-3-week groups in comparison with the model group (P<0.01), and that of the EA-3-week group was considerably increased compared with the EA-2-week group (P<0.05). Immunohistochemical staining showed that the number of SP in the hippocampus was markedly increased in the model group compared with the control group (P<0.01), and was markedly reduced in both EA-2-week and EA-3-week groups (P<0.01), and that of the EA-3-week group was significantly decreased compared with the EA-2-week group (P<0.01). The expression levels of hippocampal APP and BACE 1 proteins were significantly higher in the model group than in the control group (P<0.01), and that of hippocampal IDE was markedly lower in the model group than in the control group (P<0.01). After EA, the increased expression levels of APP and BACE 1 proteins and the decreased expression level of IDE in the EA-2-week and EA-3-week groups were significantly inhibited (P<0.01). The effects of EA-3-week were significantly stronger than those of EA-2-week in down-regulating the expression of APP and BACE 1 proteins and up-regulating the expression of IDE (P<0.01, P<0.05). CONCLUSION: EA stimulation of GV 20 and BL 23 can improve the learning-memory ability in APP/PS 1 double transgenic AD mice, which may be related to its effects in down-regulating the expression of SP, APP and BACE 1 proteins and up-regulating the expression of IDE protein in the hippocampus.
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OBJECTIVE To develop a method to evaluate the compatibility of compounds in the fluorescence resonance energy transfer (FRET) model for β-secretase (BACE1) inhibitor screening.METHODS Two commercially available BACE1 inhibitor screening systems based on FRET were selected to evaluate the BACE1 inhibitory activities of (-)-epigallocatechin-3-gallate (EGCG) and Compound 1 according to the supplier's protocol.The inhibitory rates and slopes of the catalytic curves of the inhibitors were calculated.The effect of inhibitors on the fluorescence intensity of the systems were quantitatively calculated and the comparatively evaluated.RESULTS EGCG,a reported non-competitive inhibitor of BACE1,directly induced the reduction of fluorescence intensity of one of the systems.The slope of the line with the addition of EGCG (10.8±2.6) conformed to that of the line of EGCG inhibition (10.2±3.4),which indicated that EGCG was a pseudo-positive inhibitor of BACE1.Compound 1 had little effect on the fluorescence intensity of the systems,so the inhibitory activity of Compound 1 was confirmed.The compounds which showed inhibitory activity in preliminary screening should be checked in the blank control without BACE1 to calibrate the effect of compound on the system fluorescence intensity.The applicability of the tested compounds in the screening system could thus be evaluated to prevent pseudo-positive results.CONCLUSION This fluorescence calibration method with compound control can be universally used for assays based on FRET theory to evaluate the applicability of tested BACE1 inhibitors.
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This study was designed to investigate the effect of gastrodin (GAS) against β-amyloid plaques in 5×FAD Alzheimer's disease (AD) transgenic mice, and utilize 117 cell model (over-expression of Aβ and β-secretase) to explore the underlying mechanism. 5×FAD mice model were randomly divided into three groups, including GAS-high dose group (GAS-H, 200 mg·kg-1·d-1), GAS-middle dose group (GAS-M, 100 mg·kg-1·d-1) and GAS-low dose group (GAS-L, 50 mg·kg-1·d-1). Meanwhile, the wild type mice were used in the control group. After being treated with GAS for three months, 5×FAD mice were evaluated by Morris water maze for the learning and memory ability and by ELISA for Aβ in the cerebral homogenate. Then, Aβplaques in the hippocampus and cortex of 5×FAD mice were observed and analyzed with immunohistochemical staining. The cell apoptosis rate and the cell viability were determined in vitro, after the cells were treated with different concentrations of GAS (10, 25, 50 and 100 μmol·L-1). Furthermore, Intracelluar/extracelluar Aβ were determined by ELISA. Effects of GAS on BACE (β-secretase site APP cleaving enzyme) mRNA and protein expression were analyzed in 117 cell models by Q-PCR and Western blotting. The results suggest that GAS is able to restore the learning and memory capacity of 5×FAD mice, and reduce Aβ in the cerebral homogenate and Aβ plaques in the brain. Compared with the untreated transgenic positive group, A β plaques were declined in hippocampus and cortex of GAS-H group by 93.28% and 88.88%, and A β was reduced in the cerebral homogenate by 55.74%. In vitro study suggests a dose-dependent effect of GAS in reducing Aβ in 117 cell models. When the cells were treated with 100 μmol·L-1 GAS, extracelluar Aβ and intracellular Aβ of 117 cells were reduced by 63.1% and 49.1%. BACE expression was largely suppressed in mRNA by 32.9% (P-1 GAS, the protein level was declined by 47.9% (Pβ production and accumulation by inhibiting β-secretase.
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β-secretase，a type I transmembrane aspartic protease, initiates b-amyloid protein(Aβ) formation by cleaving β- amyloid precursor protein between Met596and Asp597or between Tyr606and Glu607to generate N-terminal fragment of Aβ. β-Secretase has many members，and aspartic proteinase β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) is the most famous of them. Because BACE1 plays a significant role in the pathogenesis of Alzheimer’ s disease (AD) and a neurodegenerative disease# it has been studied fully. In this article，we review the gene and protein structure，transcription and translation，intracellular trafficking and metabolism of BACE1 and summarize substrates and homologous enzymes of BACE1. This work provides some reference for BACE1 as a drug target on AD.
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β-secretase, a typeⅠtransmembrane aspartic protease, initiates β-amyloid protein(Aβ) formation by cleaving β-amyloid precursor protein between Met596 and Asp597 or between Tyr606 and Glu607 to generate N-terminal fragment of Aβ. β-Secretase has many members,and aspartic proteinaseβ-site amyloid precursor protein-cleaving enzyme 1 (BACE1) is the most famous of them. Because BACE1 plays a significant role in the pathogenesis of Alzheimer′s disease (AD) and a neurodegenerative disease, it has been studied fully. In this article, we review the gene and protein structure, transcription and translation, intracellular trafficking and metabolism of BACE1 and summarize substrates and homologous enzymes of BACE1. This work provides some reference for BACE1 as a drug target on AD.
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Objective To investigate the effect of propofol anesthesia on the expression of β-secretase 1 (BACE1) and content of anyloid beta protein 1-42 (Aβ1-42) in the neonatal rat hippocampus.Methods Ninety Sprague-Dawley rats,aged 7 days,weighing 12-16 g,were randomly divided into 3 groups ( n =30 each):control group (group C),single dose of propofol anesthesia group (group SP),and repeated doses of propofol anesthesia group (group RP).Group C received intraperitoneal normal saline 7.5 ml/kg once a day for 7 consecutive days.Group SP received normal saline 7.5 ml/kg once a day for 6 consecutive days and propofol 75 mg/kg on 7th day.Group RP received propofol 75 mg/kg once a day for 7 consecutive days.Six rats in each group were chosen at 15 min after the end of injection on 7th day and blood samples were taken from the left ventricle for determination of the blood glucose level and for blood gas analysis.Eight animals in each group were sacrificed on 1st,3rd and 7th day after the end of injection on 7th day to determine the expression of BACE1 (using Western blot) and content of Aβ1-42 in the hippocampus (by ELISA).Results Compared with groups C and SP,the expression of BACE1 was up-regulated and the content of Aβ1-42 was significantly increased at each time point in group RP ( P ＜ 0.01 ).There was no significant difference in the expression of BACE1 and content of Aβ1-42 at each time point between groups C and SP ( P ＞ 0.05).Conclusion Repeated doses of propofol up-regulate the expression of BACE1 and increase the content of Aβ1-42 in neonatal rat hippocampus,which may be one of the mechanisms by which propofol leads to long-term cognitive dysfunction.Single dose of propofol does not have the effect.
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ObjectiveTo study the effect of exercise training on β-amyloid polypeptide (Aβ) and β-secretase(BACE) in the hippocampus of the rats with vascular dementia (VD).Methods 30 Sprague-Dawley (SD) rats were carried out to an exercise group (n =10 ),a model group (n =10 ),and a sham-operation group ( n =10 ).VD rat models were made by the ligation of bilateral common carotid arteries.Morris water maze test were carried out 4 weeks after the operation to assess the ability in learning and memory of the rats and Aβ and β-secretase (BACE)expression was detected in the hippocampus of the rats using immunohistochemical techniques.ResultsIn the Morris water maze test,the model group showed reduction in the learning and memorizing ability,with obvious longer escape latencies ( ( 101.34 ± 19.67 ) s,(95.42 ± 23.89 ) s,( 89.39 ± 22.67 ) s,( 90.12 ± 19.77 ) s,respective-ly) than that of sham-operation group ( ( 62.13 ± 11.38 ) s,( 24.84 ± 13.69 ) s,( 16.98 ± 12.51 )s,( 11.41 ± 8.93 ) s,correspond-dingly) (P ＜ 0.05 ),and the exercise group was improved in the learning and memorizing ability ( corresponding to ( 80.15 ± 21.56 ) s,( 51.24 ± 20.91 ) s,( 43.78 ± 22.36) s,( 45.67 ± 20.87 ) s ),compared with the model group(P＜0.05).The grey values of Aβ in the hippocampus of the rats for the exercise group was ( 130.12 ± 19.01 ),( 116.77 ± 23.67 ) for the model group and ( 148.44 ± 17.67 ) for the sham-operation group(P＜ 0.05).The grey values of BACE in the hippocampus of the ratsfor the exercise group were( 131.21± 25.25 ),( 120.53± 10.21 ) for the model group(P＜ 0.05 ) and ( 162.38 ± 28.11 ) for the sham-operation group (P ＜ 0.05).ConclusionExercise training can lower the expression of BACE and Aβ in the hippocampus of rats with VD,therefore improving the learning and memory ability of rats with VD.
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Objective: To establish the high-throughput screening system for β-secretase (β-site amyloid precursor protein cleaving enzyme 1, BACE1) inhibitors in vitro. Methods: Using the homogeneous time-resolved fluorescence (HTRF) technique to establish a high-throughput screening system for BACE1 inhibitors according to the extent that test compounds inhibited BACE1 activity by optimizing the incubation time, enzyme concentration and the detector. Results: A high-throughput screening system for BACE1 inhibitors based on HTRF methods was established. The incubation time was 6 h, the BACE1 concentration is 670 U/L. According to the detector of VICTOR3, the signal-to-noise (S/N) ratio reached 649.6, while the signal-to-background (S/B) ratio and Z′ factor were 44.6 and 0.91, respectively. The coefficient of variation (CV) was much lower than 10%. Using this method, the inhibitors with IC50<106mol/L could be screened out. Conclusion: The high-throughput screening system based on HTRF Could assure a high sensitivity, specificity and stability, which could be used to high-through put screening for the BACE1 inhibitors.