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Alzheimer's disease (AD) is an aging-related neurodegenerative disease and is associated with the accumulation of amyloid-β (Aβ) peptides in patient brains. AD can be classified into the familial type and sporadic type. () is the major risk gene for familial AD (fAD) because its mutations comprised over 80%of the total mutations causing fAD. PS1 is the catalytic subunit of the enzyme γ-secretase, which is responsible for the proteolytic cleavage of amyloid precursor protein (APP) to produce Aβ. Although novel fAD-causing mutations in PS1 are being reported increasingly, the molecular mechanisms underlying how these mutations induce fAD remain elusive. Since over 90%of the fAD-causing mutations in PS1 leads to a reduction of γ-secretase activity, the loss-of-function mutation hypothesis has been emerged, which suggests that the loss of PS1 functions may be the root cause of AD. Recently, increasing number of evidence supports this hypothesis. First, loss-of-function mutations increase the production of long-length Aβ by disturbing the cleavage sites of γ-secretase APP, thereby increasing the ratio of Aβ/Aβ; Second, loss-of-function mutations dysregulate endoplasmic reticulum calcium homeostasis in neurons; Third, loss-of-function mutations inhibit the autophagy activity of neurons, resulting in the abnormal accumulation of cleaved products from APP; Fourth, loss-of-function mutations alter the endocytosis and transcytosis processes in neurons, leading to neuratrophy; Fifth, loss-of-function mutations activate brain immune cells (astrocytes and microglia), which mount a strong neuroinflammation response; Last, loss-of-function mutations reduce the rates of glycolysis and the production of lactic acid, disrupting the balance of neuronal energy supply. In this article we summary the research progress on the loss-of-function hypothesis and pose several topics which would guide studies of this field in future.
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Desmoid-type fibromatosis (DF) is a rare monoclonal fibroblastic proliferation that is characterized by locally infiltrative but rarely metastatic lesions. Tyrosine kinase and γ-secretase inhibitors are primarily used in the targeted therapy of DF. The use of these drugs, however, is mainly based on the recommendations of retrospective studies with small sample sizes. Previous studies that focused on the mechanism, efficacy, and safety of targeted therapy for DF were reviewed to provide references for clinical applications and research. The efficacy and safety of targeted therapy were compared with those of other systemic therapy options. Targeted therapy does not provide considerable advantages in efficacy and safety over other medical treatments and is usually applied after the failure of antihormonal therapies, nonsteroidal anti-inflammatory drugs, and chemotherapy. Further studies are required to explore the mechanism, indications, and appropriate drug dosage of the targeted therapy of DF.
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Acne inversa is a chronic inflammatory skin disease of the folliculo-sebaceous-apocrine unit.Currently,genetic and immunological factors are hot topics in the study of its pathogenesis.Genetic factors are mainly related to γ-secretase mutations,and abnormal expression of the γ-secretase-Notch axis leads to increased keratinization of hair follicles and inflammation in some patients with haploinsufficiency of the y-secretase gene.Mutations in the γ-secretase gene are not necessary for acne inversa,and the risk of Alzheimer's disease in familial acne inversa patients still remains unclear.Some progress has been made in researches on the association of genotype with phenotype in acne inversa patients,but further studies with large sample size are needed for verification.
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OBJECTIVE: To investigate the effect of γ-secretase inhibitor DAPT in inflammation-induced brain white matter injury in neonatal mice. METHODS: Sixty C57BL/10J neonatal mice are randomly divided into control group, control+DAPT (10 mg•kg-1) group, inflammation (LPS) group, LPS+DAPT group (inflammation exposure after 10 mg•kg-1 DAPT treatment). All neonatal mice were killed and brain was removed to the following observation and detection:at P5, the mRNA expression variation of IL-1β, IL-8,TNF-α,Hes1 and NICD by Real-time PCR methods. Oligodendrocytes were identified by immunofluorescence staining. Myelin basic protein (MBP) protein expression was detected by Western blot assay. RESULTS: LPS group showed brain injury characterized by inhibition of brain development. There were significant differences in mRNA expression of IL-1β, IL-8, TNF-α, Hes1 and NICD between LPS+DAPT group and LPS group (P<0.05), and the mRNA expression of IL-1β, IL-8,TNF-α,Hes1 and NICD in inflammation-treated were significantly increased than control group (P<0.05). The results showed more expression of MBP in LPS+DAPT group compared with LPS group (P<0.05). Compared with the blank control group, which was obviously decreased after 48 h of inflammation (P<0.05).CONCLUSION: Inflammation leads to abnormal of notch signal expression in neonatal mice, and which is shows inflammation involved in brain damage.Its mechanism is probably associated with the maturation of oligodendrocytes.
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Objective To investigate the intervention effect of CD147 on learning and memory ability in rat model of Alzheimer's disease. Methods A total of 60 healthy Sprague-Dawley rats were randomly divided into sham operation group, model group and CD147 group, 20 rats in each group. All of the rats were anesthetized with intraperitoneal injection of 10％chloral hydrate (0.3 g/kg). The rats in the model group and the CD147 group were injected with Aβ1-40 (10μg) in the bilateral hippocampal CA1 regions, while the rats in the sham operation group were injected with the same amount of saline at the same sites. After 48 h, the rats in CD147 group were injected with CD147 cDNA in the bilateral ventricles, while the rats in model group and sham operation group were injected the same amount of saline at the same sites. Morris water maze test was used to detect the ability of learning and memory of rats. The expressions ofβamyloid protein (Aβ) andγ-secretase were detected by Western blot assay. Results The escape latency was significantly longer in model group than that of sham operation group, while which was significantly lower in CD147 group than that of model group (P<0.05). The number of times across the platform and the time of staying on platform were significantly lower in model group than those of sham operation group, while which was significantly higher in the CD147 group than that of model group (P<0.05). The expressions of Aβandγ-secretase were increased significantly in model group compared to those of sham operation group, while which were significantly decreased in CD147 group compared with those of model group (P<0.05). Conclusion Exogenous CD147 can significantly improve the learning and memory ability of AD rats, and its specific mechanism may be related to regulating the activity ofγ-secretase and down regulating the expression of Aβ.
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Objective To investigate the effects of Notch signaling pathway on proliferation of insulin-induced endometrial carcinoma cells and apoptosis related protein expression levels.Methods The endometrial carcinoma Ishikawa 3-H-12 cell line was primarily cultured and subcultured in vitro.Then,the cultured cells were divided into five groups:the control group (3 mL PBS was added into the group),the insulin group (cells were stimulated by 1 × 106 mol/L insulin) and MW167 groups (different doses of γ-secretase inhibitor MW167 pretreated with insulin stimulation).After 48 h culturation,inhibition of endometrial carcinoma cell growth of each group was measured by MTT-colorimetric method,the apoptosis-related proteins (Caspase-3,Caspase-8) and Notch1 protein expression levels of each group were determined by Western blot.Results Insulin can promote Notch1 protein expression in endometrial carcinoma cells,after 48 h insulin stimulation,the Notch1 protein expression level was significantly higher than that in the control group (P＜0.05).MW167 can inhibit insulin-induced Notch1 protein expression in a concentration-dependent inhibition manner.The absorbance at 570 nm (A570) of endometrial carcinoma cells cultured for 24,48 and 72 h in different groups were significantly different (P＜0.05).The A570 values in the insulin group at each time point were higher than those in the control group (P＜0.05),and the insulin-induced endometrial carcinoma cell proliferation reached its highest level at 48 h.MW167 inhibited insulin-induced endometrial carcinoma cells proliferation in a concentration-and time-dependent manner,and 20 μmol/L MW167 persistently inhibited insulin-induced proliferation of endometrial carcinoma cells at 48 h.Western blot analysis showed that expression levels of Caspase-3 and Caspase-8 protein in the insulin group at each time point were lower than those in the control group (P＜0.05),and MW167 promoted the expressions of Caspase-3 and Caspase-8 in a concentration-and time-dependent manner.Conclusion MW167 can suppress the insulin-induced endometrial carcinoma cells proliferation and promote the expression of related apoptotic proteins by inhibiting Notch signaling pathway,and induce apoptosis of endometrial carcinoma ceils.
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Objective To investigate the effects of Notch signaling pathway on proliferation of insulin-induced endometrial carcinoma cells and apoptosis related protein expression levels.Methods The endometrial carcinoma Ishikawa 3-H-12 cell line was primarily cultured and subcultured in vitro.Then,the cultured cells were divided into five groups:the control group (3 mL PBS was added into the group),the insulin group (cells were stimulated by 1 × 106 mol/L insulin) and MW167 groups (different doses of γ-secretase inhibitor MW167 pretreated with insulin stimulation).After 48 h culturation,inhibition of endometrial carcinoma cell growth of each group was measured by MTT-colorimetric method,the apoptosis-related proteins (Caspase-3,Caspase-8) and Notch1 protein expression levels of each group were determined by Western blot.Results Insulin can promote Notch1 protein expression in endometrial carcinoma cells,after 48 h insulin stimulation,the Notch1 protein expression level was significantly higher than that in the control group (P＜0.05).MW167 can inhibit insulin-induced Notch1 protein expression in a concentration-dependent inhibition manner.The absorbance at 570 nm (A570) of endometrial carcinoma cells cultured for 24,48 and 72 h in different groups were significantly different (P＜0.05).The A570 values in the insulin group at each time point were higher than those in the control group (P＜0.05),and the insulin-induced endometrial carcinoma cell proliferation reached its highest level at 48 h.MW167 inhibited insulin-induced endometrial carcinoma cells proliferation in a concentration-and time-dependent manner,and 20 μmol/L MW167 persistently inhibited insulin-induced proliferation of endometrial carcinoma cells at 48 h.Western blot analysis showed that expression levels of Caspase-3 and Caspase-8 protein in the insulin group at each time point were lower than those in the control group (P＜0.05),and MW167 promoted the expressions of Caspase-3 and Caspase-8 in a concentration-and time-dependent manner.Conclusion MW167 can suppress the insulin-induced endometrial carcinoma cells proliferation and promote the expression of related apoptotic proteins by inhibiting Notch signaling pathway,and induce apoptosis of endometrial carcinoma ceils.
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Presenilin (PS) is a transmembrane protein identified in familial early-onset Alzheimer disease, and it is mainly expressed in cell membranes and organelle membranes. As an important catalytic core of the γ-secretase multimeric enzyme complex, PS has been implicated in regulating various proteins. Recent researches have shown that mutations in PS are identified in the familial dilated cardiomyopathy, and the PS gene plays an important role in cardiac formation and regulation of calcium homeostasis in myocardial cells. In this review, we summarized the function of PS in heart and the mechanisms underlying the effects of PS on calcium homeostasis, such as amyloid β protein (Aβ), 1,4,5-inositol trisphosphate receptors, ryanodine receptors and PS as endoplasmic reticulum (ER) Ca2+ leak channels, hoping to provide a theoretical basis for the therapy of dilated cardiomyopathy.
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<p><b>OBJECTIVE</b>To observe the effects of Huannao Yicong Formula (, HYF) on learning and memory and it's regulating effect on γ-secretase related anterior pharynx defective 1 (APH-1), presenilin enhancer-2 (PEN-2) signaling pathway, so as to discuss and further clarify the mechanism of HYF on Alzheimer's disease.</p><p><b>METHODS</b>Sixty APP/PS1 transgenic mice, randomly allocated into 4 groups, the model group, the donepezil group (0.65 mg/kg), HYF low-dose group (HYF-L, 5.46 g/kg) and HYF high-dose group (HYF-H, 10.92 g/kg), 15 for each group. Another 15 C57BL/6J mice with the same age and same genetic background were allocated into the control group, proper dosage of drugs or distilled water were given by intragastric administration once daily for 12 weeks. After 12 weeks of administration, the learning and memory abilities of mice in each group was evaluated by the morris water maze test, amyloid precursor protein (APP), Aβand Aβlevels in hippocampus were detected by enzyme-linked immunosorbent assay, γ-secretase was detected by dual luciferase assaying, the levels of APH-1a, hypoxia-inducible factor 1α (HIF-1α), cAMP response element-binding protein (CREB) and PEN-2 and their mRNA expression was measured by Western blot and real-time polymerase chain reaction.</p><p><b>RESULTS</b>HYF can ameliorate learning and memory deficits in APP/PS1 transgenic mice by decreasing the escape latency, improving the number of platform crossing and swimming speed (P<0.01, P<0.05). HYF can decrease the levels of APP, Aβ, Aβand the activity of γ-secretase in hippocampus of Alzheimer's disease model mice. HYF can down-regulate the levels of CREB and PEN-2 and the expression of their mRNA.</p><p><b>CONCLUSION</b>HYF can improve the learning and memory ability by inhibiting the activity of γ-secretase through the CREB/PEN-2 signaling pathway, and this may be one of the therapeutic mechanisms of HYF in Alzheimer's disease.</p>
Subject(s)
Animals , Female , Male , Amyloid Precursor Protein Secretases , Metabolism , Amyloid beta-Protein Precursor , Metabolism , Cyclic AMP Response Element-Binding Protein , Genetics , Metabolism , Drugs, Chinese Herbal , Pharmacology , Therapeutic Uses , Endopeptidases , Genetics , Metabolism , Enzyme-Linked Immunosorbent Assay , Gene Expression Regulation , Hippocampus , Metabolism , Pathology , Hypoxia-Inducible Factor 1, alpha Subunit , Genetics , Metabolism , Immunohistochemistry , Learning , Memory Disorders , Drug Therapy , Genetics , Mice, Inbred C57BL , Mice, Transgenic , Presenilin-1 , Metabolism , Presenilin-2 , Genetics , Metabolism , RNA, Messenger , Genetics , Metabolism , Signal TransductionABSTRACT
Alzheimer's disease (AD) is known to induce alterations of mitochondrial function such as elevation of oxidative stress and activation of apopotosis. The aim of this study was to investigate the effects of human Presenilin 2 mutant (hPS2m) overexpression on the γ-secretase complex in the mitochondrial fraction. To achieve this, alterations of γ-secretase complex expression and activity were detected in the mitochondrial fraction derived from brains of NSE/hPS2m Tg mice and Non-Tg mice. Herein, the following were observed: i) overexpression of the hPS2m gene significantly up-regulated the deposition of Aβ-42 peptides in the hippocampus and cortex of brain, ii) overexpression of hPS2m protein induced alterations of γ-secretase components such as main component protein and activator protein but not stabilization-related proteins, iii) changes in γ-secretase components induced by overexpression of hPS2m protein up-regulated γ-secretase activity in the mitochondrial fraction, and iv) elevation of γ-secretase activity induced production of Aβ-42 peptides in the mitochondrial fraction. Based on these observations, these results indicate that alteration of γ-secretase activity in cells upon overexpression of hPS2m is tightly linked to mitochondrial dysfunction under the specific physiological and pathological conditions of AD.
Subject(s)
Animals , Humans , Mice , Alzheimer Disease , Brain , Hippocampus , Mice, Transgenic , Mitochondria , Oxidative Stress , Peptides , Presenilin-2 , Presenilins , Up-RegulationABSTRACT
Objective:To investigate the affection to the differentiation of Th17 cell in rat models of bronchiolitis after blocking Notch signaling by γ-secretase inhibitor and provide rationale to seek new target for bronchiolitis drug treatment. Methods:The rats were randomly divided into normal group,bronchiolitis group andγ-secretase inhibitor group. The model of bronchiolitis was established successfully by nasal dripping,and γ-secretase inhibitor(MW167) was injected into the vena caudalis. The pathological changes of the airway were observed by HE staining;the plasma level of interleukin17 ( IL-17 ) was detected by ELISA;the level of RORγt mRNA in lung tissues and peripheral blood mononuclear cells( PBMCs) was tested by real-time quantitative PCR;the levels of Notch signaling and RORγt protein in lung tissues were examined by Western blot. Results:Compared to the bronchiolitis group, the histopathologic change in MW167 intravenous injection group was significantly alleviated;the plasma level of IL-17 was decreased;the level of RORγt mRNA in lung tissues and PBMCs was lower in MW167-treated group than bronchiolitis group;the levels of Notch signaling and RORγt were decreased. Conclusion:γ-secretase inhibitor through intravenous injection suppresses the differentiation of Th17 cell and relieves the airway inflammation of bronchiolitis in rat models after blocking Notch signaling and has potential therapeutic value for treating bron-chiolitis.
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Objective To investigate the effect of notch signaling pathway on drug resistance and invasiveness of bladder cancer .Methods We observed the changes of growth and morphology of bladder cancer T 24 , 5637 and J82 cells which treated for 48 hours using γ-secretase inhibitor by inverted microscope .The mRNA and protein lev-els of the EMT molecular markers , including E-cadherin , N-cadherin , vimentin and Alpha-smooth muscle actin were examined by RT-PCR and Western blot in bladder cancer cells;Detected the changes of drug resistance and invasion respectively by MTT and Transwell in bladder cancer cells .Results After completely blocking the Notch signaling pathway , the inverted microscope showed that bladder cancer cells became smaller and more disperse ;RT-PCR and Western blot showed the mRNA and protein levels of E-cadherin were up-regulated ( P<0.05 ) , contrast , N-cadherin , vimentin and Alpha-smooth muscle actin were down-regulated ( P<0.05 ); The prolifera-tion of bladder cancer cells were significantly inhibited by MTT test;The number of through microporous membrane cells significantly decreased ( P<0.05 ) shown by Transwell test .Conclusions The Notch signaling pathway is completely blocked that nhibites proliferation and EMT of bladder cancer cells , reduces drug resistance and inva-sion in bladder cancer cells .It suggests that drug resistance and invasiveness of bladder cancer can be changed through EMT which is regulated through notch signaling pathway .
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Objective To explore the relationship between resveratrol and Notch 1 signalling pathway in podocytes.Methods Interference RNA (RNAi) and doxycycline (Dox) were used to inhibit the Sirtuin (SIRT) 1 expression in the wild-type and inducible SIRT1 shRNA (CAGGS) podocytes respectively.Recombinant mouse delta-like ligand 4 (DLL4) was used to activate Notch1 signalling.The message RNA of SIRT1,Notch1 downstream gene Hes1 and Hey2,as well as the key enzymes of Notch1 signalling pathway were detected by using real-time PCR.Western blotting was used to detect intracellular domain of Notch 1 (ICD1),SIRT1,and metalloprotease (ADAM) 10 and components of γ-secretase complex protein expression.Results In WT murine podoytes,resveratrol up-regulated ICD1 protein production,as well as the mRNA of Hes1 and Hey2 in a dose-dependent manner.Treatment with resveratrol resulted Nicastrin mRNA and protein increase in podocytes (P ＜0.05),as well as inhibit ADAM10 expression (P ＜ 0.05),but all these changes were prevented after the use of SIRT1 RNAi(P ＜ 0.05).DLL4 up-regulated the expression of mRNA of Hes1 and Hey2,as well as ICD1 protein production in a dose-dependent manner.Treatment with doxycycline resulted decrease of SIRT1 gene and protein expression in CAGGS podocytes after 24 h and 48 h respectively(P ＜ 0.05),which weakend the role of DLL4 significantly(P ＜ 0.05).Conclusion Resveratrol induces Nicastrin expression,as well as activation of Notch1 signalling pathway in a SIRT1-dependent manner.
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γ-Secretase is aⅠtransmembrane protease associated with Alzheimer disease(AD), and including four subunits:presenilin,presenilin enhancer-2,anterior-pharynx-defective1 and nicastrin. In recent studies,the ultra-high-resolution cryo-electron microscope has been used for the first time, revealing the humanγ-secretase″horseshoe″,the three-dimensional structure and the arrangement of the subunits. This technique has shed light on the regulation of the enzyme pathway and mechanism. In addition,the γ-secretase modulators,including non-steroidal anti-inflammatory drugs,have been shown in vitro to inhibit γ-secretase activity and selectively reduce the level of Aβ42 against AD. They have provided an effective approach,with broad prospects for development. Studies in this area have become a hot topic in recent years. Here we summarized the γ-secretase subunits regulatory pathways, humanγ-secretase fine three-dimensional structure andγ-secretase modulators .
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Objective By virtual screening in MDL,to search for a novel γ-secretase inhibitor.Methods A series of compounds were designed,synthesized,and evaluated based on pharmacophore model of γ-secretase inhibitors by virtual screening in MDL.Results The drug-likeness analytic data synthesized indicated that target compounds had drug-likeness.Each svnthesized compound was checked by IR spectroscopy,~1H and ~(13)C-NMR spectroscopy.Conclusion The designed compounds had better activity by model prediction.And the optimal compound showed a significant estimated activity value of 0.025 nmol/L and can be used as a lead for further drug development.