Role And The Mechanisms Of GSK-3? Acetylation Or Gestetioanl Environment Enrichment In Alzheimer-like Pathologies And The Protection

Background: Alzheimer's disease(AD)is a neurodegenerative disease characterized by the formation of neurofibrillary tangles consisting of hyperphosphorylated Tau and amyloid plaques consisting predominately of amyloid-?(A?)fibrils.Glycogen synthase kinase-3(GSK-3)is widely expressed in the nervous system.Glycogen synthase kinase-3?(GSK-3?)is an important subtype of GSK-3.The activation of GSK-3? plays an important role in the process of AD.However,the mechanism of GSK-3? activity increase in AD is still unclear.Our previous experiments found that GSK-3? acetylation increased in AD,but the role of GSK-3? acetylation in the occurrence and development of AD and its mechanism are still unclear.Objective: To explore the role of GSK-3? acetylation in the occurrence and development of AD and the molecular mechanism.Methods: The mimic acetylation at GSK-3? K15 point mutation plasmid was overexpressed in many cell lines.Western blotting,immunoprecipitation and immunohistochemical techniques were used to detect the effects of simulated acetylation at GSK-3? K15 on its protein level,ubiquitination level and degradation.The ability of lernning and mermrry,phosphorylation of tau protein,activation of glias and the level of synapse-associated proteins were examined in mice infected acetylated point mutation adeno-associated virus in hippocampal CA1 region by using western blotting,immunoprecipitation,mice behavior test,immunohistochemistry and immunofluorescence techniques.Tau-k18(-)plasmid was overexpressed in many cell lines.The effects of Tau-transferase activity on GSK-3? protein level,acetylation level,ubiquitination level and degradation were detected.The acetylation of purified protein in vitro was used to verify the direct acetylation effect of Tau on GSK-3?.Results:1.Elevated acetylation levels of GSK-3? K15 in various AD mouse modelsThe acetylation modification of the GSK-3? lysine 15 in the HEK293 trans-Tau model was determined by mass spectrometry,and a specific antibody that recognizes the GSK-3? lysine 15 site acetylation was prepared according to the results.A variety of AD mouse models(3x Tg,APP/PS1,Tau+)found elevated levels of GSK-3? acetylation detected by this antibody.2.GSK-3? acetylation at K15 enhances its enzymatic activity and inhibits its ubiquitination and degradationThe GSK-3? K15 Q plasmid was constructed to mimic the acetylation of GSK-3? K15.It was found that GSK-3? K15 Q significantly enhanced its protein kinase activity and significantly reduced the degradation and ubiquitination of GSK-3?.3.GSK-3? acetylation at K15 leads to cognitive impairment and mood disordersThe adeno-associated virus of GSK-3? K15 Q,mimic the acetylation of GSK-3?-lysine 15 site,was injected into the hippocampal CA1 region of C57 mice.It was found that GSK-3? K15 Q can cause cognitive impairment and mood disorder in mice.4.GSK-3? acetylation at K15 promotes Tau hyperphosphorylation and activation of glial cellsGSK-3? K15 Q adeno-associated virus was injected into the hippocampal CA1 region of C57 mice,and it was found that the GSK-3? K15 Q group promoted hyperphosphorylation of Tau in the hippocampus of mice and significantly activated microglia and astrocytes.5.GSK-3? acetylation at K15 leads to synaptic plasticity damage.GSK-3? K15 Q adeno-associated virus was injected into the hippocampal CA1 region of C57 mice.It was found that GSK-3? K15 Q caused a decrease in the expression of synapse-associated proteins in mice.6.Tau promotes GSK-3? acetylation at K15 and increased its protein levels and activityAD transgenic mice and cells showed that Tau increased the acetylation of GSK-3? lysine 15 and resulted in increased protein level and enzyme activity of GSK-3?.7.Tau acetyltransferase region mediates elevated the protein level and the acetylation of GSK-3?,and decreased its ubiquitination.We constructed the Tau-K18(-)plasmid which was abolished the acetyltransferase activity of Tau.Tau-K18(-)abolished Tau induced increase of GSK-3? protein level,increased GSK-3? acetylation level,decreased GSK-3? ubiquitination level.8.Tau protein can directly acetylate GSK-3?The purified protein of Tau,Tau-K18(-)and GSK-3? was constructed.In vitro acetylation experiments showed that Tau can directly acetylate GSK-3?,and Tau-K18(-)abolished its acetylation of GSK-3?.Conclusion: The acetylation of GSK-3? can increase its enzymatic activity and promote AD pathology,Tau protein can acetylate GSK-3?.Acetylation of GSK-3? can competitively inhibit its ubiquitination,thereby inhibiting its protein degradation and enhancing its enzyme activity.Background: Building brain reserves before dementia onset could represent a promising strategy to prevent Alzheimer's disease(AD),while how to initiate early cognitive stimulation is unclear.Given that the immature brain is more sensitive to environmental stimuli and that brain dynamics decrease with ageing,we reasoned that it would be effective to initiate cognitive stimulation against AD as early as the fetal period.Methods: After conception,maternal AD transgenic mice(3 x Tg AD)were exposed to gestational environment enrichment(GEE)until the day of delivery.The cognitive capacity of the offspring was assessed by the Morris water maze and contextual fear-conditioning tests when the offspring were raised in a standard environment to 7 months of age.Western blotting,immunohistochemistry,real-time PCR,immunoprecipitation,chromatin immunoprecipitation(Ch IP)assay,electrophysiology,Golgi staining,activity assays and sandwich ELISA were employed to gain insight into the mechanisms underlying the beneficial effects of GEE on embryos and 7–10-month-old adult offspring.Results: We found that GEE markedly preserved synaptic plasticity and memory capacity with amelioration of hallmark pathologies in 7–10-m-old AD offspring.The beneficial effects of GEE were accompanied by global histone hyperacetylation,including those at bdnf promoter-binding regions,with robust BDNF m RNA and protein expression in both embryo and progeny hippocampus.GEE increased insulin-like growth factor 1(IGF1)and activated its receptor(IGF1R),which phosphorylates Ca2+/calmodulin-dependent kinase IV(Ca MKIV)at tyrosine sites and triggers its nuclear translocation,subsequently upregulating histone acetyltransferase(HAT)and BDNF transcription.The upregulation of IGF1 mimicked the effects of GEE,while IGF1 R or HAT inhibition during pregnancy abolished the GEE-induced Ca MKIV-dependent histone hyperacetylation and BDNF upregulation.Conclusions: These findings suggest that activation of IGF1R/Ca MKIV/HAT/BDNF signaling by gestational environment enrichment may serve as a promising strategy to delay AD progression.