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@#Objective To express insulin-degrading enzyme(IDE)mutant T142A in prokaryotic cells and detect its activity.Methods According to the results of multi-sequence alignment and IDE substrate co-crystal structure,an active residue in β6-strand structure of IDE were predicted.The recombinant plasmid ppSUMO-T142A,with the site mutation of threonine 142 to alanine,was constructed by point mutation technique and expressed by E.coli prokaryotic expression system.After purification by nickel ion column affinity chromatography,ion exchange chromatography and gel filtration chromatography,the mutant T142A was obtained and determined for the activity by fluorescence method.Results IDE amino acid sequence is highly conserved among 16 species.T142 directly participates in substrate binding,interacts with substrate cleavage sites,and is close to important structures such as catalytic active sites and door-subdomains.The mutation of recombinant plasmid ppSUMO-T142A was proved to be correct by sequencing.The expressed fusion protein His-SUMO-T142A was mainly existed in soluble form in the supernatant at a concentration of 18 mg/mL,with a relative molecular mass of about 131 000;After three steps of purification,the purity of mutant T142A reached 86%.The maximum reaction rate(V_(max))of T142A catalytic degradation of fluorescent substrate V was 501.06 min~(-1) and the Michaelis constant(K_m) was 9.01μmol/L.Compared with wild-type IDE(V_(max) was 2 814.32 min~(-1),K_m was 11.93μmol/L),the activity of T142A decreased significantly.Conclusion The activity of IDE mutant T142A expressed in this study greatly decreases,while T142 is an important residue for IDE to play its enzymatic function,which provides an experimental basis for the development of new IDE activity regulatory molecules.
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Objective: To observe the effect of Hei Xiaoyaosan on expressions of β-amyloid 1-42 peptide(Aβ1-42),glycogen synthase kinase-3β(GSK-3β),neprilysin(NEP),insulin-degrading enzyme(IDE) in the hippocampus area of Alzheimer's dementia mice. Method: After weighing, 42 APP/PSI bivalent transgenic mice were randomly divided into 4 groups:10 mice in the model group, 10 mice in the positive drug control group, 11 mice in the high-dose Hei Xiaoyaosan group, and 11 mice in the low-dose Hei Xiaoyaosan group; 10 wild C57BL/6J mice of the same age and strain were used for negative control group. Drugs were administered to mice by gavage once a day for 12 weeks. Then the behavior of all the mice were detected by Morris water maze, the morphological changes in hippocampal neurons were observed by hematoxylineosin(HE) staining, the expressions of Aβ1-42, GSK-3β, NEP and IDE proteins in hippocampus were detected by immunohistochemistry. Result: After 3 months of treatment, compared with negative control groups, the average escaping latency periods prolonged significantly, and the number of cross-platform was decreased significantly in model group (Pβ1-42 and GSK-3β proteins in model mice hippocampus were significantly increased (PPPβ1-42 and GSK-3β proteins in the hippocampus of drug groups were significantly decreased (PPPConclusion: Hei Xiaoyaosan can significantly improve the learning and memory abilities of AD mice, which may be related to the reduction of cognitive impairment in AD mice by regulating abnormal deposition and degradating Aβ in the hippocampus.
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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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This study was aimed to observe different forms of β-amyloid peptide (Aβ) and insulin degrading enzyme (IDE) in the hippocampus and cortex in order to further explore the role of Aβ and IDE on spleen yin deficiency di-abetes-associated cognitive decline (DACD), and the effect of Zi-Bu Pi-Y in method. The rats were randomly divided into five groups, which were the blank control (Cont) group, diabetes (DM) group, spleen yin deficiency (pi) group, spleen yin deficiency diabetes (piDM) group and Zi-Bu Pi-Y in recipe (ZBPYR) group. Soluble and insoluble Aβ in the hippocampus and cortex of rats were extracted by gradient centrifugation, and then measured by ELISA. The ex-pression of IDE was observed by western blot. The results showed that the content of soluble and insoluble Aβ1-42 in the hippocampus and cortex of the DM group and piDM group were higher than the Cont group. The soluble and in-soluble Aβ1-42 content in the hippocampus and cortex of the ZBPYR group were reduced compared with the DM group and the piDM group. The soluble Aβ1-40 in the cortex of the DM group, pi group and piDM group were in-creased compared with the Cont group (P < 0.05). The soluble Aβ1-40 content of the ZBPYR group was decreased compared with the DM group and the piDM group (P < 0.05). The expression of IDE protein was decreased in the hippocampus of the DM group and the piDM group compared with the Cont group (P< 0.05), and the IDE protein level in the hippocampus of the ZBPYR group was increased compared with the DM group and the piDM group (P<0.05). The expression of IDE protein in the cortex of the DM group, pi group and piDM group was lower than the Cont group (P< 0.05). The IDE protein level in the cortex of the ZBPYR group was reduced compared to the DM group (P< 0.05). It was concluded that the increased Aβ1-42 in brain may be a major pathological change of DACD and spleen yin deficiency DACD. The decreased IDE expression may be one of the reasons to induce increasing of Aβ1-42 level. The Zi-Bu Pi-Y in method may decrease the Aβ1-42 content by upregulating IDE protein expression.
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Objective To investigate the effects of rehabilitation training on hippocampal amyloid-beta peptide (Aβ) and insulin-degrading enzyme (IDE) levels in vascular dementia (VD).Methods Thirty female Sprague-Dawley rats were randomly assigned to a rehabilitation group (n =10),a model group (n =10) or a sham-operation group (n =10).An experimental VD model was established in the rats of the first 2 groups by bilateral common carotid artery permanent ligation.The rats in the rehabilitation group then received 1 h of rehabilitation training daily.Learning and memory were assessed at 4 weeks aftet the operation.Immunohistochemical staining was used to detect Aβ and IDE expression in the hippocampus dentate gyrus (DG) area.Results The rats in the rehabilitation group showed significantly better learning ability compared with the model group.The expression of Aβ in the rehabilitation group was significantly less than in the model group.The expression of IDE in the rehabilitation group was significantly greater Conclusion Rehabilitation can accelerate the recovery of learning and memory in VD,at least in rats The mechanism is possibly related to decreased accumulation of Aβ in the hippocampus due to up-regulation of the expression of IDE.
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Objective To investigate the mechanisms of decreasing insulin degrading enzyme (IDE) level by mutation V97L in the gene presenilin 1 (PS-1).Methods Transcription factor GATA binding protein 3 (GATA-3) activity was assessed by protein/DNA array and verified by Western blot in SH-SY5Y cells transfected by PS-1 mutation V97L.Results Protein/DNA array and Western blot revealed that there was increased transcript factor activity (5.5 times high) and protein level of GATA-3 in V97L-PS-1 transfected SH-SY5Y cells.Transcription factor GATA-3 can bind to the IDE promoter and negatively control the IDE transcription level.Conclusion PS-1 mutation V97L may regulate the transcription of IDE via GATA-3, and subsequently involve in deposition of Aβ42 and development of Alzheimer's disease.
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Exercise training is highly correlated with the reduced glucose-stimulated insulin secretion (GSIS), although it enhanced insulin sensitivity, glucose uptake and glucose transporter expression to reduce severity of diabetic symptoms. This study investigated the impact of short-term swimming exercise on insulin regulation in the Goto-Kakizaki (GK) rat as a non-obese model of non-insulin-dependent diabetes mellitus. Wistar (W/S) and GK rats were trained 2 hours daily with the swimming exercise for 4 weeks, and then the changes in the metabolism of insulin and glucose were assessed. Body weight was markedly decreased in the exercised GK rats compare to their non-exercised counterpart, while W/S rats did not show any exercise-related changes. Glucose concentration was not changed by exercise, although impaired glucose tolerance was improved in GK rats 120 min after glucose injection. However, insulin concentration was decreased by swimming exercise as in the decrease of GSIS after running exercise. To identify the other cause for exercise-induced insulin down-regulation, the changes in the levels of key factors involved in insulin production (C-peptide) and clearance (insulin-degrading enzyme; IDE) were measured in W/S and GK rats. The C-peptide level was maintained while IDE expression increased markedly. Therefore, these results showed that insulin down-regulation induced by short-term swimming exercise likely attributes to enhanced insulin clearance via IDE over-expression than by altered insulin production.
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Animaux , Rats , Poids , Peptide C , Diabète de type 2 , Régulation négative , Glucose , Transporteurs de glucose par diffusion facilitée , Insuline , Insulinorésistance , Insulinase , Course à pied , NatationRésumé
? amyloid protein(A?) including A?40 and A?42 are the important bioactive substances in vivo.Their toxic and beneficial attributes in the body depend on its concentration.The brain A? level is maintained by two balances under the physiological condition.The first balance is the generation involved in ?-secretase and ?-secretase and the degradation involved in neprilysin(NEP) and insulin-degrading enzyme(IDE) of A?. The second one is the balance between the receptor for advanced end glycation products(RAGE)-mediated influx and low-density lipoprotein receptor related protein 1(LRP1)-mediated efflux of A? across the blood-brain barrier(BBB).Breakdowning any one of the two balances would result in the aggregation and precipitation of A? in the brain,which is a crucial event in the pathogenesis of Alzheimer's disease(AD).This paper reviews the regulation of brain A? level under the physiological condition and the reducing strategies on the level of brain A? under the pathological condition for developing new drugs in the treatment of AD.