Intracellular accumulation of tau is a hallmark pathology in Alzheimer disease (AD) and the related tauopathies, thus targeting tau could be promising for drug development. Proteolysis Targeting Chimera (PROTAC) is a novel drug discovery strategy for selective protein degradation from within cells. Methods: A novel small-molecule PROTAC, named as C004019 with a molecular mass of 1,035.29 dalton, was designed to simultaneously recruite tau and E3-ligase (Vhl) and thus to selectively enhance ubiquitination and proteolysis of tau proteins. Western blotting, immunofluoresence and immunohistochemical staining were employed to verify the effects of C004019 in cell models (HEK293 and SH-SY5Y) and mouse models (hTau-transgenic and 3xTg-AD), respectively. The cognitive capacity of the mice was assessed by a suite of behavior experiments. Electrophysiology and Golgi staining were used to evaluate the synaptic plasticity. Results: C004019 induced a robust tau clearance via promoting its ubiquitination-proteasome-dependent proteolysis in HEK293 cells with stable or transient overexpression of human tau (hTau), and in SH-SY5Y that constitutively overexpress hTau. Furthermore, intracerebral ventricular infusion of C004019 induced a robust tau clearance in vivo . Most importantly, both single-dose and multiple-doses (once per 6 days for a total 5 times) subcutaneous administration of C004019 remarkably decreased tau levels in the brains of wild-type, hTau-transgenic and 3xTg-AD mice with improvement of synaptic and cognitive functions. Conclusions: The PROTAC (C004019) created in the current study can selectively and efficiently promote tau clearance both in vitro and in vivo , which provides a promising drug candidate for AD and the related tauopathies.

BackgroundBoth type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) are common age-associated disorders and T2DM patients show an increased risk to suffer from AD, however, there is currently no marker to identify who in T2DM populations will develop AD. Since glycogen synthase kinase-3β (GSK-3β) activity, ApoE genotypes and olfactory function are involved in both T2DM and AD pathogenesis, we investigate whether alterations of these factors can identify cognitive impairment in T2DM patients.MethodsThe cognitive ability was evaluated using Minimum Mental State Examination (MMSE) and Clinical Dementia Rating (CDR), and the mild cognitive impairment (MCI) was diagnosed by Petersen's criteria. GSK-3β activity in platelet, ApoE genotypes in leucocytes and the olfactory function were detected by Western/dot blotting, the amplification refractory mutation system (ARMS) PCR and the Connecticut Chemosensory Clinical Research Center (CCCRC) test, respectively. The odds ratio (OR) and 95% confidence intervals (95% CI) of the biomarkers for MCI diagnosis were calculated by logistic regression. The diagnostic capability of the biomarkers was evaluated by receiver operating characteristics (ROC) analyses.FindingsWe recruited 694 T2DM patients from Jan. 2012 to May. 2015 in 5 hospitals (Wuhan), and 646 of them met the inclusion criteria and were included in this study. 345 patients in 2 hospitals were assigned to the training set, and 301 patients in another 3 hospitals assigned to the validation set. Patients in each set were randomly divided into two groups: T2DM without MCI (termed T2DM-nMCI) or with MCI (termed T2DM-MCI). There were no significant differences for sex, T2DM years, hypertension, hyperlipidemia, coronary disease, complications, insulin treatment, HbA1c, ApoE ε2, ApoE ε3, tGSK3β and pS9GSK3β between the two groups. Compared with the T2DM-nMCI group, T2DM-MCI group showed lower MMSE score with older age, ApoE ε4 allele, higher olfactory score and higher rGSK-3β (ratio of total GSK-3β to Ser9-phosphorylated GSK-3β) in the training set and the validation set. The OR values of age, ApoE ε4 gene, olfactory score and rGSK-3β were 1.09, 2.09, 1.51, 10.08 in the training set, and 1.06, 2.67, 1.47, 7.19 in the validation set, respectively. The diagnostic accuracy of age, ApoE ε4 gene, olfactory score and rGSK-3β were 0.76, 0.72, 0.66, 0.79 in the training set, and 0.70, 0.68, 0.73, 0.79 in the validation set, respectively. These four combined biomarkers had the area under the curve (AUC) of 82% and 86%, diagnostic accuracy of 83% and 81% in the training set and the validation set, respectively.InterpretationAging, activation of peripheral circulating GSK-3β, expression of ApoE ε4 and increase of olfactory score are diagnostic for the mild cognitive impairment in T2DM patients, and combination of these biomarkers can improve the diagnostic accuracy.

Overexpressing Tau counteracts apoptosis and increases dephosphorylated β‐catenin levels, but the underlying mechanisms are elusive. Here, we show that Tau can directly and robustly acetylate β‐catenin at K49 in a concentration‐, time‐, and pH‐dependent manner. β‐catenin K49 acetylation inhibits its phosphorylation and its ubiquitination‐associated proteolysis, thus increasing β‐catenin protein levels. K49 acetylation further promotes nuclear translocation and the transcriptional activity of β‐catenin, and increases the expression of survival‐promoting genes (bcl2 and survivin), counteracting apoptosis. Mutation of Tau's acetyltransferase domain or co‐expressing non‐acetylatable β‐catenin‐K49R prevents increased β‐catenin signaling and abolishes the anti‐apoptotic function of Tau. Our data reveal that Tau preserves β‐catenin by acetylating K49, and upregulated β‐catenin/survival signaling in turn mediates the anti‐apoptotic effect of Tau.

Increasing evidence suggests that glycogen synthase kinase-3β (GSK-3β) plays a crucial role in neurodegenerative/psychiatric disorders, while pan-neural knockout of GSK-3β also shows detrimental effects. Currently, the function of GSK-3β in specific type of neurons is elusive. Here, we infused AAV-CaMKII-Cre-2A-eGFP into GSK-3βlox/lox mice to selectively delete the kinase in excitatory neurons of hippocampal dentate gyrus (DG), and studied the effects on cognitive/psychiatric behaviors and the molecular mechanisms. We found that mice with GSK-3β deletion in DG excitatory neurons displayed spatial and fear memory defects with an anti-anxiety behavior. Further studies demonstrated that GSK-3β deletion in DG subset inhibited hippocampal synaptic transmission and reduced levels of GluN1, GluN2A and GluN2B (NMDAR subunits), GluA1 (AMPAR subunit), PSD93 and drebrin (postsynaptic structural proteins), and synaptophysin (presynaptic protein). GSK-3β deletion also suppressed the activity-dependent neural activation and calcium/calmodulin-dependent protein kinase II (CaMKII)/CaMKIV-cAMP response element binding protein (CREB) signaling. Our data suggest that GSK-3β in hippocampal DG excitatory neurons is essential for maintaining synaptic plasticity and memory.

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The Maelstrom (MAEL) gene is a cancer-testis (or cancer-germline) gene, which is predominantly expressed in germline cells under normal conditions, but is aberrantly expressed in a range of human cancer cells. In germline cells, MAEL is found predominantly in the nuage, where it plays an essential role in piRNA biogenesis and piRNA-mediated silencing of transposons. However, the role of MAEL in cancer has not been elucidated. We performed immunoprecipitation and Nano-LC-MS/MS analysis to investigate the interactome of MAEL, and identified 14 components of stress granules (SGs) as potential binding partners of MAEL in MDA-MB-231 human breast cancer and SW480 colorectal cancer cells. The interactions between MAEL and 8 of these SG components (PABPC1, YBX1, KHSRP, SYNCRIP, DDX39, ELAV1, EIF4A1 and EIF3F) were confirmed by anti-tag immunoprecipitation. Immunofluorescence analysis showed that MAEL co-localizes with the SG marker PABPC1 in SGs during oxidative stress. Nuages and SGs are the cytoplasmic RNA granules of germline cells and stressed somatic cells, respectively, and both serve as a platform for small RNA-mediated gene silencing. It is, therefore, suggested that MAEL may be involved in miRNA-mediated gene silencing in SGs, as it does in the nuage. This finding should be valuable toward understanding the function of MAEL in carcinogenesis.

Recent studies suggest that spatial training can maintain associative memory capacity in Tg2576 mice, but it is not known whether the beneficial effects can be inherited from the trained fathers to their offspring. Here, we exposed male wild-type and male 3XTg Alzheimer disease (AD) mice (3-m old) respectively to spatial training for one week and assessed the transgenerational effects in the F1 offspring when they were grown to 7-m old. We found that the paternal spatial training significantly enhanced progeny's spatial cognitive performance and synaptic transmission in wild-type mice. Among several synapse-or memory-associated proteins, we observed that the expression level of synaptotagmin 1 (SYT1) was significantly increased in the hippocampus of the paternally trainedoffspring. Paternal training increased histone acetylation at the promoter of SYT1 in both fathers' and the offspring's hippocampus, and as well as in the fathers' sperm. Finally, paternal spatial training for one week did not improve memory and synaptic plasticity in 3XTg AD F1 offspring. Our findings suggest paternal spatial training for one week benefits the offspring's cognitive performance in wild-type mice with the mechanisms involving an enhanced transgenerational histone acetylation at SYT1 promoter. Physical training1-4 and mental 5-8 or physiological stimulations 9 to parents not only influence the individuals per se 1, 2, 4, 10 , but also affect the behavioral performance, emotion, and cognitive functions of their children [5][6][7]9 . For example, paternal odor fear conditioning enhances the offspring's behavioral sensitivity to the F0-conditioned smell with an increasing neuroanatomical manifestation of the Olfr151 pathway 9 . In human, maternal tristimania during pregnancy augments risk of psychiatric disorders in the offspring, especially in female fetuses 11 . In an animal study, fathers' MSUS (maternal separation combined with maternal stress) improves goal-directed behaviors and behavioral flexibility in the adult offspring, and this effect is demonstrated by epigenetic transformations including histone posttranslational modifications at the mineralocorticoid receptor (MR) gene promoter and decreased MR expression in the hippocampus 12 . However, the sole effects of fathers' experience on offspring have seldom been studied.Alzheimer's disease (AD) is the most common neurodegenerative disorder characterized pathologically by amyloidogenesis and neurofibrillary degeneration 13,14 and clinically memory deterioration started by spatial memory loss 15,16 . To date, there is no efficient cure for this devastating disorder. Recent studies suggest that spatial training can maintain associative memory capacity with enhancement of dendrite ramification and spine

Background Human Tau (hTau) accumulation and synapse loss are two pathological hallmarks of tauopathies. However, whether and how hTau exerts toxic effects on synapses remain elusive. Methods Mutated hTau (P301S) was overexpressed in the N2a cell line, primary hippocampal neurons and hippocampal CA3. Western blotting and quantitative polymerase chain reaction were applied to examine the protein and mRNA levels of synaptic proteins. The protein interaction was tested by co‐immunoprecipitation and proximity ligation assays. Memory and emotion status were evaluated by a series of behavioural tests. The transcriptional activity of nuclear factor‐erythroid 2–related factor 2 (NRF2) was detected by dual luciferase reporter assay. Electrophoresis mobility shift assay and chromosome immunoprecipitation were conducted to examine the combination of NRF2 to specific anti‐oxidative response element (ARE) sequences. Neuronal morphology was analysed after Golgi staining. Results Overexpressing P301S decreased the protein levels of post‐synaptic density protein 93 (PSD93), PSD95 and synapsin 1 (SYN1). Simultaneously, NRF2 was decreased, whereas Kelch‐like ECH‐associated protein 1 (KEAP1) was elevated. Further, we found that NRF2 could bind to the specific AREs of DLG2, DLG4 and SYN1 genes, which encode PSD93, PSD95 and SYN1, respectively, to promote their expression. Overexpressing NRF2 ameliorated P301S‐reduced synaptic proteins and synapse. By means of acetylation at K312, P301S increased the protein level of KEAP1 via inhibiting KEAP1 degradation from ubiquitin–proteasome pathway, thereby decreasing NRF2 and reducing synapse. Blocking the P301S–KEAP1 interaction at K312 rescued the P301S‐suppressed expression of synaptic proteins and memory deficits with anxiety efficiently. Conclusions P301S‐hTau could acetylate KEAP1 to trigger synaptic toxicity via inhibiting the NRF2/ARE pathway. These findings provide a novel and potential target for the therapeutic intervention of tauopathies.