γ-Secretase Inhibitors Selected by Molecular Docking, to Develop a New Drug Against Alzheimer's Disease.

Background: Alzheimer´s disease (AD) is one of the most common forms of dementia, is characterized by memory loss and cognitive impairment that affects more than 30 million people worldwide. The pathogenesis of Alzheimer's disease is primary driven by brain accumulation of the amyloid ß peptide generated from the amyloid-ß precursor protein (APP) via cleavages by ß- and γ-secretase. In this study, we propose an approach by molecular docking to select compounds as γ-secretase inhibitors for decreasing the APP generation. Methods: We selected potential γ-secretase inhibitors by molecular docking in the potential site between Asp257, Lue268, Asp385, Ile387, Phe388, and Leu432 amino acids in presenilin-1 (PS-1), using a chemical library of over 500,000 compounds. Results: Eight compounds (AZ1 - AZ8) were selected by molecular docking to develop γ-secretase inhibitors for decreasing the APP generation. Conclusions: AZ1 - AZ8 compounds could be interacting in the potential site between Asp257, Lue268, Asp385, Ile387, Phe388, and Leu432 amino acids in PS-1. These compounds could specifically interact in the binding pocket in PS-1 to prevent/decrease the APP generation, to develop a new drug against Alzheimer's disease.

Impaired autophagy in amyloid-beta pathology: A traditional review of recent Alzheimer's research.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder. The major pathological changes in AD progression are the generation and accumulation of amyloid-beta (Aß) peptides as well as the presence of abnormally hyperphosphorylated tau proteins in the brain. Autophagy is a conserved degradation pathway that eliminates abnormal protein aggregates and damaged organelles. Previous studies have suggested that autophagy plays a key role in the production and clearance of Aß peptides to maintain a steady-state of Aß peptides levels. However, a growing body of evidence suggests that autophagy is significantly impaired in the pathogenesis of AD, especially in Aß metabolism. Therefore, this article reviews the latest studies concerning the mechanisms of autophagy, the metabolism of Aß peptides, and the defective autophagy in the production and clearance of Aß peptides. Here, we also summarize the established and new strategies for targeting autophagy in vivo and through clinical AD trials to identify gaps in our knowledge and to generate further questions.

The evolved divergence of γ-secretase-susceptibility of homologous proteins Ngfrb and Nradd in zebrafish.

OBJECTIVE: NGFR/p75NTR and NRADD/NRH proteins are closely related structurally and are encoded by genes that arose from a duplication event early in vertebrate evolution. The transmembrane domain (TMD) of NGFR is cleaved by γ-secretase but there is conflicting data around the susceptibility to γ-secretase cleavage of NRADD proteins. If NGFR and NRADD show differential susceptibility to γ-secretase, then they can be used to dissect the structural constraints determining substrate susceptibility. We sought to test this differential susceptibility. RESULTS: We developed labelled, lumenally-truncated forms of zebrafish Ngfrb and Nradd and a chimeric protein in which the TMD of Nradd was replaced with the TMD of Ngfrb. We expressed these in zebrafish embryos to test their susceptibility to γ-secretase cleavage by monitoring their stability using western immunoblotting. Inhibition of γ-secretase activity using DAPT increased the stability of only the Ngfrb construct. Our results support that only NGFR is cleaved by γ-secretase. Either NGFR evolved γ-secretase-susceptibility since its creation by gene duplication, or NRADD evolved to be refractory to γ-secretase. Protein structure outside of the TMD of NGFR is likely required for susceptibility to γ-secretase.

Phosphodiesterase Inhibitors for Alzheimer's Disease: A Systematic Review of Clinical Trials and Epidemiology with a Mechanistic Rationale.

BACKGROUND: Preclinical studies, clinical trials, and reviews suggest increasing 3',5'-cyclic adenosine monophosphate (cAMP) and 3',5'-cyclic guanosine monophosphate (cGMP) with phosphodiesterase inhibitors is disease-modifying in Alzheimer's disease (AD). cAMP/protein kinase A (PKA) and cGMP/protein kinase G (PKG) signaling are disrupted in AD. cAMP/PKA and cGMP/PKG activate cAMP response element binding protein (CREB). CREB binds mitochondrial and nuclear DNA, inducing synaptogenesis, memory, and neuronal survival gene (e.g., brain-derived neurotrophic factor) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α). cAMP/PKA and cGMP/PKG activate Sirtuin-1, which activates PGC1α. PGC1α induces mitochondrial biogenesis and antioxidant genes (e.g.,Nrf2) and represses BACE1. cAMP and cGMP inhibit BACE1-inducing NFκB and tau-phosphorylating GSK3ß. OBJECTIVE AND METHODS: We review efficacy-testing clinical trials, epidemiology, and meta-analyses to critically investigate whether phosphodiesteraseinhibitors prevent or treat AD. RESULTS: Caffeine and cilostazol may lower AD risk. Denbufylline and sildenafil clinical trials are promising but preliminary and inconclusive. PF-04447943 and BI 409,306 are ineffective. Vinpocetine, cilostazol, and nicergoline trials are mixed. Deprenyl/selegiline trials show only short-term benefits. Broad-spectrum phosphodiesterase inhibitor propentofylline has been shown in five phase III trials to improve cognition, dementia severity, activities of daily living, and global assessment in mild-to-moderate AD patients on multiple scales, including the ADAS-Cogand the CIBIC-Plus in an 18-month phase III clinical trial. However, two books claimed based on a MedScape article an 18-month phase III trial failed, so propentofylline was discontinued. Now, propentofylline is used to treat canine cognitive dysfunction, which, like AD, involves age-associated wild-type Aß deposition. CONCLUSION: Phosphodiesterase inhibitors may prevent and treat AD.

Effect of Notch-Hes1 signaling blockade by a γ-secretase inhibitor on the expression of γδT17 cells in a mouse model of psoriasis-like skin inflammation / 中华皮肤科杂志

Objective@#To evaluate the effect of Notch-Hes1 signaling blockade by a γ-secretase inhibitor on the expression of γδT17 cells in a mouse model of psoriasis-like skin inflammation.@*Methods@#Forty-five healthy specific pathogen-free (SPF) male BALB/c mice were randomly divided into control group, model group and intervention group by simple random sampling. The model group and intervention group were both topically treated with imiquimod 5% cream (62.5 mg once a day) on the shaved back, the intervention group were then intraperitoneally injected with the γ-secretase inhibitor DAPT (10 mg/kg once a day) immediately after topical application of imiquimod, and the control group were topically treated with equivalent amount of vaseline once a day. After 6-day treatment, psoriasis area and severity index (PASI) was used to evaluate changes of skin lesions. On day 7, blood samples were obtained from all the mice through heart puncture after anesthetization, and spleen and skin tissues were acquired to prepare single cell suspension. Spleen index was compared among the 3 groups. Skin tissues on the mouse back were resected and subjected to hematoxylin-eosin staining to observe histopathological changes. Flow cytometry was performed to determine the percentage of γδT17 cells in the spleen and skin tissues, real-time reverse transcription (RT) -PCR to measure the mRNA expression of Hes1 in single cell suspension of the spleen, and enzyme-linked immunosorbent assay (ELISA) to determine the serum level of interleukin (IL) -17A. Statistical analysis was carried out by using one-way analysis of variance and repeated measures analysis of variance for comparison of indices among groups, and Pearson correlation analysis for evaluating the correlation between different indices.@*Results@#Twenty-four hours after the final treatment, the intervention group showed milder psoriasis-like skin inflammation, lower PASI score, and milder degree of epidermal thickening and dermal inflammatory cell infiltration compared with the model group. The model group showed significantly increased spleen index (12.534 ± 1.636) , proportions of γδT17 cells in the spleen (24.659% ± 4.603%) and skin tissues (22.127% ± 5.670%) , mRNA expression of Hes1 in the spleen (4.867 ± 0.543) , and serum level of IL-17A ([22.478 ± 2.776] ng/L) compared with the control group (all P < 0.01) . However, the above indices were significantly lower in the intervention group (9.449 ± 1.040, 14.966% ± 5.770%, 13.631% ± 5.946%, 2.541 ± 0.347, [18.639 ± 1.816] ng/L) than in the model group (all P < 0.01) . In the model group and intervention group, there were positive correlations between the proportions of γδT17 cells in the spleen and serum levels of IL-17A (r = 0.56, 0.53 respectively, both P < 0.05) , between the proportions of γδT17 cells in skin lesions and PASI scores (r = 0.56, 0.52 respectively, both P < 0.05) , as well as between the mRNA expression of Hes1 in the spleen and the proportions of γδT17 cells (r = 0.61, 0.58 respectively, both P < 0.05) or serum levels of IL-17A (r = 0.60, 0.54 respectively, both P < 0.05) .@*Conclusion@#Notch-Hes1 signaling blockade by γ-secretase inhibitor can markedly inhibit the expression of γδT17 cells, and effectively alleviate the severity of psoriasis-like skin inflammation in mouse models.

Evidence For and Against a Pathogenic Role of Reduced γ-Secretase Activity in Familial Alzheimer's Disease.

The majority of mutations causing familial Alzheimer's disease (fAD) have been found in the gene PRESENILIN1 (PSEN1) with additional mutations in the related gene PRESENILIN2 (PSEN2). The best characterized function of PRESENILIN (PSEN) proteins is in γ-secretase enzyme activity. One substrate of γ-secretase is encoded by the gene AMYLOID BETA A4 PRECURSOR PROTEIN (AßPP/APP) that is a fAD mutation locus. AßPP is the source of the amyloid-ß (Aß) peptide enriched in the brains of people with fAD or the more common, late onset, sporadic form of AD, sAD. These observations have resulted in a focus on γ-secretase activity and Aß as we attempt to understand the molecular basis of AD pathology. In this paper we briefly review some of the history of research on γ-secretase in AD. We then discuss the main ideas regarding the role of γ-secretase and the PSEN genes in this disease. We examine the significance of the "fAD mutation reading frame preservation rule" that applies to PSEN1 and PSEN2 (and AßPP) and look at alternative roles for AßPP and Aß in fAD. We present a case for an alternative interpretation of published data on the role of γ-secretase activity and fAD-associated mutations in AD pathology. Evidence supports a "PSEN holoprotein multimer hypothesis" where PSEN fAD mutations generate mutant PSEN holoproteins that multimerize with wild type holoprotein and dominantly interfere with an AD-critical function(s) such as autophagy or secretion of Aß. Holoprotein multimerization may be required for the endoproteolysis that activates PSENs' γ-secretase activity.

Expression of Notch1, Jagged1 and NICD in epithelial ovarian carcinomas and a preliminary study on the activity of gamma-secretase in epithelial ovarian carcinoma cell lines / 中华妇产科杂志

Objective To study the expression of Notch 1,Jagged1 and Notch intracellular domain (NICD) in epithelial ovarian carcinoma tissues and analyze the clinical significance.To explore the activity of γ-secretase in epithelial ovarian carcinoma cell line SKOV3 and the effect of N-[N-(3,5-dil uorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT),a γ-secretase inhibitor on the activity of γ-secretase in SKOV3.Methods Immunohistochemistry staining method was performed in 43 patients with epithelial ovarian carcinoma and 11 patients with benign epithelial ovarian tumor to detect the expression of Notch1,Jagged1 and NICD.The differences of expressionof Notch1,Jagged1 and NICD between malignant and benign ovarian tumors was compared and alsoanalyzed the correlation with clinicopathological parameters of ovarian carcinoma.Human serous ovarian cancer cell line SKOV3 and immortalized nontumorigenic ovarian epithelial cell line T29 were incubated in vitro.The activities of γ-secretase in SKOV3 and T29 with dimethyl sulfoxide (DMSO) and DAPT were detected respectively by Gal4VP16/UAS and dual luciferase reporter assay system.Results (1) The immunohistochemical composite scores (ICS) of Notch1 in epithelial ovarian carcinoma (6.7±2.2) were not significantly different with those in benign epithelial ovarian tumor (5.4± 2.7,P=0.153),while the ICS of Jagged 1 and NICD in epithelial ovarian carcinoma (5.3± 2.4,5.3± 2.3) were higher than those in benign epithelial ovarian tumor (1.6± 1.4,3.1± 1.7; all P＜0.01).The expression of Notch 1,Jagged 1 and N ICD had no correlation with patients' aged,history of carcinoma,ascites,the level of serum CA125,maximum length of ovarian tumor,Federation International of Gynecology and Obstetrics (FIGO) stage,grade and pathology subtypes (all P＞0.05).The hazard ratio between the high expression of Notch1,Jagged1,or NICD and the moderate to low expression of Notch1,Jagged1,or NICD,and Jagged1 were 0.771,1.648 and 1.316,respectively (all P＞0.05).The 5-year survival rate and median survival time between the high expression of Notch,Jagged 1 or NICD in subgroup and moderate to low expression in subgroup were of no difference (all P＞0.05).The activity of γ-secretase in SKOV3 was significantly higher than that in T29 [(12.2± 1.4)％,P=0.019].(2)After DAPT treated,the relative activity of γ-secretase in SKOV3 (50 μmol/L) was declined from (100.0±5.3)％ to (6.6±0.8)％ (P=0.001).Conclusions Jagged1 and NICD in Notch1 pathway may play a key role in the occurrence of ovarian carcinoma.The activity of γ-secretase in epithelial ovarian carcinoma was higher than that in ovarian epithelial cell which suggest that DAPT,γ-secretase inhibitor,may become the target of ovarian carcinoma treatment.

Platelet α and β secretase activities in mild cognitive impairment and Alzheimer's disease / 中华神经科杂志

Objective To investigate platelet α and β secretase activities and the amounts of platelet soluble fragment of APP (sAPPα) produced by α-secretase in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD).Methods The neurological functions of 48 nondemented patients,42 MCI and 40 AD patients were evaluated by neuropsychological examinations.The platelet α and β secretase activities and sAPPα production in each group were measured by fluorescence and Western blotting analysis respectively.Results The α secretase activities in non-demented,MCI and AD group were 100.0％ ± 10.6％,78.2％ ± 9.4％ and 61.8％ ± 7.2％ respectively.As compared with nondemented group,the α secretase activities in MCI and AD group were decreased (F =22.935,P =0.001).The α secretase activity in AD group was significantly lower than MCI group.The β secretase activities in non-demented,MCI and AD group were 100.0％ ± 11.2％,145.8％ ± 12.7％ and 189.8％ ± 14.2％respectively.The β secretase activities in MCI and AD group were significantly higher than that in nondemented group (F =16.368,P =0.001).The β secretase activity in AD group was significantly decreased as compared with MCI group.The sAPPα amounts in MCI group and AD group were all decreased as compared with that in control group; the sAPPo amount in AD patients was significantly decreased as compared with that in MCI group.Conclusions The platelet α secretase activity and its production sAPPα in MCI and AD patients are decreased,while β secretase activity is increased,as compared with that in control group; the altered α and β secretase activities may participate in the pathogenesis of MCI and AD patients and may have diagnostic potential for them.

Association between promoter polymorphisms of a disintegrin and metalloproteinase 10 gene and sporadic Alzheimer's disease / 中华神经科杂志

ObjectiveTo investigate the relationship between the polymorphisms of the promoter of a disintegrin and metalloproteinase 10(ADAM10) gene and sporadic Alzheimer's disease (SAD).Methods The promoter of ADAM10 gene in 10 controls and 10 SAD patients was sequenced.Three variations were found,then these variations in 298 SAD patients (SAD group) and 315 healthy controls (control group)were genotyped by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).ResultsThree polymorphisms were found in the promoter of ADAM10 gene: -279G/A (rs653765),- 630G/T( rs514049 ) and - 921GAGA/- ( rs33926666 ).For - 921GAGA/-,there were significant differences in genotype ( GAGA/GAGA:138 (46.3％ ),GAGA/-:155(52.0％),-/-:5(1.7％))and allele frequencies (GAGA:431 (73.6％),-:165 (27.7％) ) between SAD and control (genotype:x2 =34.130,P =0.000; allele:x2 =25.972,P =0.000). For - 279G/A,there were significant differences in genotype and allele frequencies between SAD and control in the subjects without ApoEε4 allele (genotype:x2 =8.734,P=0.013; allele:x2 =5.129,P=0.024). -279G and -921GAGA were relatively protective allele types for SAD,and they were not in linkage disequilibrium.ConclusionThe polymorphisms - 279G/A and - 921GAGA/- of ADAM10 are associated with SAD.Allele G or genotype G/G of -279G/A and the GAGA/GAGA genotype or the GAGA allele of -921GAGA/- might have a protective effect on SAD.

Distribution and expression of anterior pharynx-defective-1 in mice central nervous system of APP/PS1 transgenic Alzheimer's disease model / 中华老年医学杂志

ObjectiveTo investigate the distribution and expression of y-secretase subunit (APH-1)in the central nervous system (CNS) of APP/PS1 double transgenic Alzheimer's disease (AD) adult mouse model,and to detect the expression difference of APH-1 in developmental brain between AD model mouse and wild-type littermates in order to further clarify the relationship between APH-1 and AD. MethodsOffspring bred by APP/PS1 double transgenic AD mice were genotyped.Immunohistochemical staining was used to detect APH-1 distribution and expression in the CNS of adult APP/PS1 double transgenic AD mouse model,in the brain of AD model mouse and its wild-type littermates on postnatal day 1,7,21 and 120.Results APH-1 was widely expressed in almost all regions of the CNS,especially in the cerebral cortex,hippocampus,olfactory bulb,hypothalamus,ventral striatum,caudate putamen,raphe magnus nucleus,cerebellum,brainstem and spinal cord of the adult APP/PS1 double transgenic mice.APH-1 expression was higher in the cortex of both AD and wild type mouse on postnatal day 1 than on postnatal day 7 and 21 with increased level of APH-1 protein in adult mouse brain.APH-1 expression in the brain of AD mice was higher than in its wild type littermates at any stage(P＜0.05).Conclusions Distribution of APH-1 is ubiquitous and region-dependent in the CNS.The different distribution and expression between APP/PS1 double transgenic mouse model and its wild type littermate indicate that APH-1 may be related to AD.

Effect of atorvastatin on ADAM10 in hippocampus of chronic cerebral hypoperfusion in rats / 国际脑血管病杂志

Objective To investigate the learning and memory functions,expression changes of disintegrin and metalloprotease 10 (ADAM10) mRNA in hippocampus in the aged rats with chronic cerebral hypoperfusion as well as the effect of atorvastatin on them.Methods A total of 72 rats were randomly divided into sham operation,cerebral hypoperfusion and atorvastatin treatment groups.A permanent bilateral common carotid artery occlusion (2VO)model was induced.Atorvastatin 10 mg/(kg · d) was administered orally after procedure in the atorvastatin treatment group.Real-time fluorescence quantitative polymerase chain reaction was used to detect the expression of ADAM10 mRNA in bilateral hippoocampus at 1,2,4,and 16 weeks after modeling,Results Two weeks after modeling,the learning and memory functions were decreased significantly in the cerebral hypoperfusion group compared to the sham operation group (P ＜ 0.05).At 4 and 16 weeks after modeling,they were further decreased (P ＜0.01); there were no significant differences in the learning and memory functions at 1,2,and 3 weeks after modeling between the atorvastatin treatment group and the cerebral hypoperfusion group,however,they were improved significantly at 16 weeks compared to the cerebral hypoperfusion group (P＜0.01).The expression of ADAM10 mRNA in hippocampus at different time points after modeling in the cerebral hypoperfusion group was down-regulated by 22％,43％,35％,and 50％,respectively compared to the sham operation group (all P ＜0.05).The expression of ADAM 10 mRNA in hippocampus at 2 weeks in the atorvastatin treatment group was higher than 22％ in the cerebral hypoperfusion group (P＜0.05).There were not significant differences at other time points.Conelusions Chronic cerebral hypoperfusion results in the down-regulation of the expression of ADAM10 mRNA in hippocampus in the aged rats,and atorvastatin may inhibit down-regulation of the expression of ADAM10 mRNA at early stage.

Expression of Notch3 and Notch intracellular domain in ovarian carcinoma and effect of N-[N-(3,5-difluorophenyl) acetyl-L-alanyl]-S-phenyl glycine t-butyl ester on ovarian carcinoma cell / 中华妇产科杂志

Objective To study the expression and clinical significance of Notch3 and Notch intracellular domain (NICD) in ovarian carcinoma and the effects of N-[N-(3 ,5-difluorophenyl) acetyl-L-alanyl]-S-phenyl glycine t-butyl ester (DAPT), a γ-secretase inhibitor on the proliferation and apoptosis in OVCAR3, A2780 ovarian carcinoma cell lines. Methods Western blot was used to detect the expression of NICD in the tissues from 58 ovarian carcinomas patients and 21 normal ovarie, who were admitted in Peking University First Hospital from July 2006 to June 2009. Immunohistochemistry was also used to detect the expression of Notch3 in these tissues. The relationship with clinical features of ovarian carcinoma was also analyzed. Proliferation of OVCAR3 and A2780 ovarian cancer cells was determined by methyl thiazolyl tetrazolium (MTT) assay, cell cycles and apoptosis and index of proliferation were detected by flow cytometry method. The expression of NICD in OVCAR3 and A2780 cells incubated with DAPT was detected by western blot. Results (1)The expression level of NICD in ovarian carcinomas was significantly higher than that in normal ovarian tissues (1.64 ±0. 19 vs. 0.98 ±0.20;P <0.05). The NICD expression was higher in ovarian cancers with low grade or advanced stage than those in high-middle grade or early stage,respectively (1.90 ± 0. 22 vs. 1.25 ± 0. 21,1.80 ± 0. 21 vs. 1.21 ± 0. 15; all P < 0. 05). The Notch3 protein was stained positively in cytoplasm, nuclear and cell membrane. The expression of Notch3 was higher in ovarian carcinomas than that in normal ovaries [78% (45/58) vs. 24% (5/21); P < 0. 01]. While,there were no stasistical difference in different pathological types, stages, differentiation of ovarian carcinoma. There was no difference between the patients with adjuvant chemotherapy or not. (2)After OVCAR3 and A2780 cells incubated with DAPT 24, 48, 72 hours, NICD expression was significantly lower than that in control group (P < 0. 05). The effects of DAPT inhibited the proliferation and prompted the apoptosis of OVCAR3 and A2780 cells were depended on the concentrations and times. Conclusions Notch3 and NICD may play a key role in the occurrence and progress of ovarian carcinoma. The mechanism of DAPT inhibited the proliferation and prompted the apoptosis of OVCAR3 and A2780 cells may be due to decreased the formation of NICD.

Effects of phosphatidylinositol-3 kinase/serine threonine kinase pathway on expression of beta-site amyloid precursor protein cleaving enzyme-1 in the hippocampus neurons / 中华神经科杂志

Objective To investigate the effect of phosphatidylinesitol-3 kinase/serine threonine kinase (PI3K/Akt) signaling pathway on expression of beta-site amyloid precursor protein cleaving enzyme-1 (BACE1) in the hippocampus neurons of rat brain. Methods Forty SD rats were randomly divided into 4 groups: blank control group, sham-operated group, insulin group and wortmannin group. Insulin or the specific inhibitor of PI3K, wortmannin was injected into hippocampus neurons to activate or inhibit the signaling pathway in insulin group or wortmannin group, respectively. Immunoprecipitation and Western blot were used to analyze the proteins levels of PI3K/Akt and BACE1. Results In insulin treatment group,among the proteins downstream of signaling pathway, expression of Akt increased (0. 952±0.060 vs 0.835±0.029,t=4.9150, P=0.0001), phospho-Akt set473 increased (0.800±0.075 vs 0.657± 0.025,t=4.5598, P=0.0002), phospho-GSK-3α decreased (0.604±0.062 vs 0.726±0.041, t= 3.5871, P=0.0018 ), and the expression of mature BACE1 and β-CTF significantly decreased. In wortmannin group, the expression of Akt and phospho-Akt ser473 were inhibited; phospho-GSK-3α increased ; mature BACEI (1.004±0.096) and β-CTF (1.031±0.048) increased (t=11.5980, P= 0.0000 and t =4.2194, P =0.0004, respectively). Conclusions PI3K/Akt signaling pathway might effect the expression of BACE1, in which impaired signaling pathway may cause the amyloid precursor protein to be easily processed by BACE1, and thus involves the pathology of Alzheimer' s disease.