Regulation Of Tau Phosphorylation Research Articles

Alterations of tau and Camk2 in acute stroke and effects of a multicomponent drug

Abstract Background Stroke is one of the leading causes of death around the world. The sequelae of ischemic stroke cause drastic effects on the quality of life for patients. Sanwujiaowan (SWJW) is a mixture prepared with 5 herbal medicines (Aconiti Lateralis Radix Praeparata, Aconiti Kusnezoffii Radix, Polygoni Multiflori Radix, Aconiti Radix, and Olibanum), with a long history of application in treating the sequelae of stroke. Objectives To provide evidence and decipher the mechanism of SWJW in alleviating stroke. Materials and Methods In this article, we expanded the indicators of SWJW by an integrated strategy based on signature metabolomics, target proteins, and bioinformatics and probed into the mechanism of SWJW intervention in ischemic stroke in a rat model. Results The results indicated that SWJW protected rats from nerve damage during the acute phase of ischemic stroke by regulating tau phosphorylation via the PI3K/Akt pathway. Conclusions This study, for the first time, proved that the reduction of phosphorylated tau was harmful for the neural function in the acute phase of ischemic stroke. Meanwhile, the pathological changes of phosphorylated tau proteins were detected in stroke and recalled by SWJW. This finding may provide a new reference for formulating treatment strategies for the acute phase of ischemic stroke.

FUBP3 mediates the amyloid-β-induced neuronal NLRP3 expression.

JOURNAL/nrgr/04.03/01300535-202507000-00028/figure1/v/2024-09-09T124005Z/r/image-tiff Alzheimer's disease is characterized by deposition of amyloid-β, which forms extracellular neuritic plaques, and accumulation of hyperphosphorylated tau, which aggregates to form intraneuronal neurofibrillary tangles, in the brain. The NLRP3 inflammasome may play a role in the transition from amyloid-β deposition to tau phosphorylation and aggregation. Because NLRP3 is primarily found in brain microglia, and tau is predominantly located in neurons, it has been suggested that NLRP3 expressed by microglia indirectly triggers tau phosphorylation by upregulating the expression of pro-inflammatory cytokines. Here, we found that neurons also express NLRP3 in vitro and in vivo, and that neuronal NLRP3 regulates tau phosphorylation. Using biochemical methods, we mapped the minimal NLRP3 promoter and identified FUBP3 as a transcription factor regulating NLRP3 expression in neurons. In primary neurons and the neuroblastoma cell line Neuro2A, FUBP3 is required for endogenous NLRP3 expression and tau phosphorylation only when amyloid-β is present. In the brains of aged wild-type mice and a mouse model of Alzheimer's disease, FUBP3 expression was markedly increased in cortical neurons. Transcriptome analysis suggested that FUBP3 plays a role in neuron-mediated immune responses. We also found that FUBP3 trimmed the 5' end of DNA fragments that it bound, implying that FUBP3 functions in stress-induced responses. These findings suggest that neuronal NLRP3 may be more directly involved in the amyloid-β-to-phospho-tau transition than microglial NLRP3, and that amyloid-β fundamentally alters the regulatory mechanism of NLRP3 expression in neurons. Given that FUBP3 was only expressed at low levels in young wild-type mice and was strongly upregulated in the brains of aged mice and Alzheimer's disease mice, FUBP3 could be a safe therapeutic target for preventing Alzheimer's disease progression.

Abeta and Tau impair retromer‐mediated cargo trafficking via distinct mechanisms

AbstractBackgroundEvidence from neuronal pathology and experimental models suggest that endolysosomal dysfunction may contribute to Alzheimer’s Disease (AD) pathogenesis, however it is unclear how Aβ and Tau directly affect endolysosomal dynamics, partially due to a lack of reporters. The retromer, including VPS35, VPS26, and VPS29, is a conserved protein complex responsible for recycling proteins within the endolysosomal pathway. Retromer regulates Tau phosphorylation and pathogenic processing of the amyloid precursor protein. Cation‐independent Mannose 6‐phosphate receptor (CIMPR) is a well‐established retromer cargo, with a WLM motif recognized by the retromer for retrieval.MethodTo track retromer‐dependent protein trafficking in vivo, I have cloned the cytoplasmic tail of CIMPR carrying the WLM motif into a pUAST‐attb vector and generated a transgenic fly line (UAS‐CIMPR‐WLM). A transgenic line carrying CIMPR, but having WLM mutated to AAA, has also been developed as a negative control (UAS‐CIMPR‐AAA). I examined the CIMPR reporter in Vps35 and Vps29 mutants, as well as established Drosophila AD models during aging.ResultThe protein level of CIMPR‐WLM was reduced by genetic ablation of Vps35, possibly due to promoted degradation. Expressed in young Vps29 mutant brains, CIMPR‐WLM showed an increased colocalization with a late endosomal/lysosomal marker Arl8, indicating a promoted delivery of retromer cargoes into the lysosome. Further, neuronal expression of CIMPR‐WLM exhibited a punctate distribution, which was abolished when WLM was mutated to AAA. Altogether, my data suggested that CIMPR‐WLM worked as a retromer‐dependent reporter. While the reporter was broadly enriched within neuropil regions in control animals (Elav>CIMPR), neuronally expression of Aβ (Elav> Aβ+CIMPR) led to a striking redistribution of CIMPR, shifting from neuropil to enrichment in soma, and forming large perinuclear puncta. Moreover, the retromer reporter was mislocalized in brains from 1‐day‐old Elav> Aβ animals, and this result did not significantly change with aging. Interestingly, Elav>Tau+CIMPR animals showed no noticeable effects on the distribution of CIMPR‐WLM on day 1, but caused a similar redistribution of CIMPR‐WLM to the perinuclei region at day 30.ConclusionThe CIMPR‐WLM reporter requires the retromer for proper cellular localization. Our findings are consistent with the notion that Aβ and Tau affect endosomal sorting, but likely via distinct mechanisms.

Increasing O-GlcNAcylation Attenuates tau Hyperphosphorylation and Behavioral Impairment in rTg4510 Tauopathy Mice.

Tauopathies such as Alzheimer's disease (AD) are characterized by abnormal hyperphosphorylation of the microtubule-associated protein tau (MAPT) aggregating into neurofibrillary tangles (NFTs). O-linked β-N-acetylglucosamine (O-GlcNAc) modifications have been suggested to regulate tau phosphorylation and aggregation and N-acetylglucosaminidase (OGA) removes GlcNAc moieties from proteins. We investigated effects of the OGA inhibitor Thiamet G in rTg4510 primary neuronal cultures and in rTg4510 mice. The rTg4510 mice overexpress human tau harboring the P301L mutation and display an age-dependent progression of tau pathology including hyperphosphorylated tau species and NFTs. Aged rTg4510 mice exhibit a non-mnemonic behavioral defect involving a hyperactive phenotype that is associated with the progression of tau pathology. Thiamet G increased overall O-GlcNAc levels and crossed the blood brain barrier in rTg4510 mice. The free fraction of Thiamet G in the brain was 22-fold above the half maximal effective concentration (EC50) measured in rTg4510 primary neurons. Chronic Thiamet G treatment (18 weeks) initiated in young 6 week old rTg4510 mice increased brain O-GlcNAc levels and this corresponded with a significant reduction in soluble and insoluble hyperphosphorylated tau in aged 24 week old rTg4510 mice. Levels of normally phosphorylated P301L tau were not altered under these conditions. Reduction of hyperphosphorylated tau species by increased O-GlcNAcylation was associated with significant attenuation of hyperactivity in 24 week old rTg4510 mice. Our findings support the pharmacological inhibition of OGA as a potential therapeutic approach for the treatment of AD and other tauopathies.

The γ-Adducin 1-357 fragment promotes tau pathology.

Tau phosphorylation is a pathological hallmark of Alzheimer's disease (AD). Previously, we reported that the γ-adducin 1-357 fragment is present in the brains of AD patients. However, it remains unknown how γ-adducin regulates tau phosphorylation. The aim of this project is to investigate the effects of the γ-adducin 1-357 fragment on tau phosphorylation and the kinases involved in this process. Full-length γ-adducin or the γ-adducin 1-357 fragment was expressed in HEK293 cells, SH-SY5Y cells, and primary neurons. The phosphorylation of tau Ser396 was determined using Western blot and immunofluorescence. Tau P301S transgenic mice were injected with adeno-associated virus encoding full-length γ-adducin or γ-adducin 1-357 fragment to determine the phosphorylation of tau. The γ-adducin 1-357 fragment enhances tau phosphorylation at Ser396. Additionally, the expression of the γ-adducin 1-357 fragment leads to the activation of glycogen synthase kinase-3β (GSK-3β). This effect was mitigated by the GSK-3β inhibitor 4-Benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD-8). The γ-adducin 1-357 fragment enhances tau phosphorylation by activating GSK3β. These results support that the fragmentation of γ-adducin may play a pivotal role in tau pathology.

Retraction Note: VPS35 regulates tau phosphorylation and neuropathology in tauopathy.

Retraction Note: VPS35 regulates tau phosphorylation and neuropathology in tauopathy.

Molecular hydrogen attenuates sepsis-induced cognitive dysfunction through regulation of tau phosphorylation.

Sepsis-associated encephalopathy (SAE) is a cognitive dysfunction caused by sepsis. Hyperphosphorylated tau is considered to play a significant role in the progression of neurodegenerative disease and also contributes to cognitive dysfunction in septic mice. Molecular hydrogen (H2) plays an antioxidant and anti-inflammatory role, and plays a protective role in septic mice. This study explored the possible effects of H2 on cognition and tau phosphorylation in a mouse model of SAE. The model of sepsis was established in C57BL/6J male mice by cecal ligation and puncture surgery. Mice treated with 2% H2 inhalation for 60min at 1h and 6h after surgery, respectively. HY-15769, the inhibitor of Tau Tubulin Kinase 1 (TTBK1), was injected 1h before the surgery. The 7-day survival rates of the mice were recorded. Cognitive behavior was tested with both novel object recognition and the Y-maze novelty arm recognition on day 7 after surgery. Hematoxylin-eosin staining was used to observe the histological damage in CA1 region of hippocampus. The expression of inflammatory factors in hippocampus was assessed by Elisa. Western blotting was adopted to determine the tau phosphorylation levels at AT8 epitopes (pSer202 and pThr205) and T22 epitopes (neurofibrillary tangle protein oligomer), and the GSK3β phosphorylation levels (Tyr216), as well as p-Ser422 and TTBK1 levels in the hippocampus. The number of dendritic spine and mushroom type of dendritic spines in the hippocampus were assessed by Golgi staining. The survival rate, visual and spatial learning ability, and memory ability were improved in septic mice treated with H2. After H2 treatment, the density of dendritic spine, mushroom type of dendritic spine, and the number of normal hippocampal neurons were progressively elevated. H2 decreased the levels of phosphorylated tau protein, tau oligomer and TTBK1, as well as the phosphorylation of tau key kinase. Furthermore, the injection of HY-15769 (a TTBK1 inhibitor) protected SAE through the similar way. The protective effect of H2 on cognitive dysfunction induced by SAE may be achieved by inhibiting tau phosphorylation, which is perhaps related with the inhibition of TTBK1.

Role of Tau in Various Tauopathies, Treatment Approaches, and Emerging Role of Nanotechnology in Neurodegenerative Disorders.

A few protein kinases and phosphatases regulate tau protein phosphorylation and an imbalance in their enzyme activity results in tau hyper-phosphorylation. Aberrant tau phosphorylation causes tau to dissociate from the microtubules and clump together in the cytosol to form neurofibrillary tangles (NFTs), which lead to the progression of neurodegenerative disorders including Alzheimer's disease (AD) and other tauopathies. Hence, targeting hyperphosphorylated tau protein is a restorative approach for treating neurodegenerative tauopathies. The cyclin-dependent kinase (Cdk5) and the glycogen synthase kinase (GSK3β) have both been implicated in aberrant tau hyperphosphorylation. The limited transport of drugs through the blood-brain barrier (BBB) for reaching the central nervous system (CNS) thus represents a significant problem in the development of drugs. Drug delivery systems based on nanocarriers help solve this problem. In this review, we discuss the tau protein, regulation of tau phosphorylation and abnormal hyperphosphorylation, drugs in use or under clinical trials, and treatment strategies for tauopathies based on the critical role of tau hyperphosphorylation in the pathogenesis of the disease. Pathology of neurodegenerative disease due to hyperphosphorylation and various therapeutic approaches including nanotechnology for its treatment.

The Strategies for Treating "Alzheimer's Disease": Insulin Signaling May Be a Feasible Target.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by senile plaques formed by amyloid-beta (Aβ) extracellularly and neurofibrillary tangles (NFTs) formed by hyperphosphorylated tau protein intracellularly. Apart from these two features, insulin deficiency and insulin resistance have also been observed in AD brains. Thus, AD has also been referred to as type 3 diabetes by some of the scientists in this field. Insulin plays a pivotal role in learning and memory and is involved in regulating tau phosphorylation though the PI3KAkt-GSK3b signaling pathway. Interestingly, recent studies revealed that in AD brains the microglia transformed into a disease-associated microglia (DAM) status in a TREM2-dependent manner to restrain the toxicity of Aβ and propagation of tau. This also correlated with PI3K-Akt signaling through the adaptor of TREM2. Whether insulin has any effect on microglia activation in AD pathology is unclear so far. However, many studies demonstrated that diabetes increased the risk of AD. In this review, we summarize the main strategies for curing AD, including lowering the level of Aβ, suppressing the phosphorylation of tau, the ablation and/or repopulation of microglia, and especially the supply of insulin. We also propose that attention should be given to the influences of insulin on microglia in AD.

Retromer subunit, VPS29, regulates vacuolar‐type ATPase and lysosomal acidification in the aging brain

AbstractBackgroundThe retromer, including VPS35, VPS26, and VPS29, is an evolutionarily conserved protein complex that retrieves cargoes from the endosome to the trans‐Golgi network or plasma membrane. Retromer regulates Tau phosphorylation and pathogenic processing of the amyloid precursor protein, both of which are neuropathological hallmarks of Alzheimer’s disease (AD). Previously, we found that loss of VPS29 in Drosophila causes progressive lysosomal dysfunction during aging, but the underlying molecular mechanism remains elusive.MethodTo investigate the molecular events in Drosophila heads caused by loss of Vps29, we performed quantitative proteomics on Vps29 mutants and age‐matched control animals, and identified 480 significant, differentially expressed proteins. To study the lysosomal acidity in fly Vps29 mutants, we neuronally expressed LAMP1‐GFP, a pH‐sensitive indicator that is localized to the lysosomal lumen. To evaluate the potential translational relevance of our findings, we knocked down retromer subunits in mammalian cell culture and examined levels of vacuolar‐type ATPase (v‐ATPase) subunits. We also interrogated available human postmortem brain proteomic data from the Religious Orders Study and Rush Memory and Aging Project (ROSMAP).ResultUnbiased proteomics from VPS29 mutant flies revealed a sharp decline in subunits of the v‐ATPase, a multimeric proton pump that is primarily responsible for lysosomal acidification. Importantly, we obtained consistent evidence from mammalian cell culture. In aged Vps29 mutant fly brains, the LAMP1‐GFP pH sensor indicated impaired lysosomal acidification. Lastly, based on ROSMAP human brain proteomics, we found that VPS29 protein levels were significantly coexpressed with other proteins implicated in energy‐coupled proton transmembrane transport, including multiple subunits of the conserved v‐ATPase.ConclusionOur findings highlight a conserved role for retromer in regulating the v‐ATPase, possibly contributing to lysosomal acidification. Drosophila is a powerful model system for functional dissection of the retromer in the mammalian brains, including in AD pathogenesis.

Small RNA Sequencing in the Tg4-42 Mouse Model Suggests the Involvement of snoRNAs in the Etiology of Alzheimer's Disease.

The Tg4-42 mouse model for sporadic Alzheimer's disease (AD) has unique features, as the neuronal expression of wild type N-truncated Aβ4-42 induces an AD-typical neurological phenotype in the absence of plaques. It is one of the few models developing neuron death in the CA1 region of the hippocampus. As such, it could serve as a powerful tool for preclinical drug testing and identification of the underlying molecular pathways that drive the pathology of AD. The aim of this study was to use a differential co-expression analysis approach for analyzing a small RNA sequencing dataset from a well-established murine model in order to identify potentially new players in the etiology of AD. To investigate small nucleolar RNAs in the hippocampus of Tg4-42 mice, we used RNA-Seq data from this particular tissue and, instead of analyzing the data at single gene level, employed differential co-expression analysis, which takes the comparison to gene pair level and thus affords a new angle to the interpretation of these data. We identified two clusters of differentially correlated small RNAs, including Snord55, Snord57, Snord49a, Snord12, Snord38a, Snord99, Snord87, Mir1981, Mir106b, Mir30d, Mir598, and Mir99b. Interestingly, some of them have been reported to be functionally relevant in AD pathogenesis, as AD biomarkers, regulating tau phosphorylation, TGF-β receptor function or Aβ metabolism. The majority of snoRNAs for which our results suggest a potential role in the etiology of AD were so far not conspicuously implicated in the context of AD pathogenesis and could thus point towards interesting new avenues of research in this field.

Androgens Regulate Tau Phosphorylation Through Phosphatidylinositol 3-Kinase-Protein Kinase B-Glycogen Synthase Kinase 3β Signaling.

Age-related testosterone depletion in men is a risk factor for Alzheimer's disease (AD). How testosterone modulates AD risk remains to be fully elucidated, although regulation of tau phosphorylation has been suggested as a contributing protective action. To investigate the relationship between testosterone and tau phosphorylation, we first evaluated the effect of androgen status on tau phosphorylation in 3xTg-AD mice. Depletion of endogenous androgens via gonadectomy resulted in increased tau phosphorylation that was prevented by acute testosterone treatment. Parallel alterations in the phosphorylation of both glycogen synthase kinase 3β (GSK3β) and protein kinase B (Akt) suggest possible components of the underlying signaling pathway. To further explore mechanism, primary cultured neurons were treated with a physiological concentration of testosterone or its active metabolite dihydrotestosterone (DHT). Results showed that testosterone and DHT induced significant decreases in phosphorylated tau and significant increases in phosphorylation of Akt and GSK3β. Pharmacological inhibition of phosphatidylinositol 3-kinase (PI3K) effectively inhibited androgen-induced increases in Akt and GSK3β phosphorylation, and decreases in tau phosphorylation. In addition, androgen receptor (AR) knock-down by small interfering RNA prevented androgen-induced changes in the phosphorylation of Akt, GSK3β and tau, suggesting an AR-dependent mechanism. Additional experiments demonstrated androgen-induced changes in Akt, GSK3β and tau phosphorylation in AR-expressing PC12 cells but not in AR-negative PC12 cells. Together, these results suggest an AR-dependent pathway involving PI3K-Akt-GSK3β signaling through which androgens can reduce tau phosphorylation. These findings identify an additional protective mechanism of androgens that can improve neural health and inhibit development of AD.

Tau acetylation at K280 regulates tau phosphorylation

Purpose/aim of the study Accumulation of hyperphosphorylated tau is a key pathological finding of Alzheimer’s disease. Recently, acetylation of tau is emerging as another key pathogenic modification, especially regarding the acetylation of tau at K280 of the hexapeptide 275VQIINK280, a critical sequence in driving tau aggregation. However, the relationship between these two key post-translational modifications is not well known. In this study, effect of acetylation of tau at K280 on tau phosphorylation profile was investigated. Materials and methods The human neuroblastoma cell line, SH-SY5Y, was transfected with p300 acetyltransferase and tau to induce acetylation of tau. Phosphorylation profile after acetylation was evaluated on western blot. K280A-mutant tau was transfected to investigate the effect of acetylation of tau at K280 on tau phosphorylation profile. Results Overexpression of p300 acetyltransferase in tau-transfected SH-SY5Y human neuroblastoma cells increased acetylation of tau. Meanwhile, tau and its phosphorylation also increased at various sites such as S199/202, S202/T205, T231, and S422, but not at S396. However, blocking acetylation only at K280 with K280A-mutant tau reversed the increased phosphorylation of tau at S202/T205, T231, and S422, but not at S199/202 or S396. Conclusion Here we identified tau phosphorylation profile in the context of p300-induced acetylation and K280A-mutant tau, demonstrating that tau acetylation affects phosphorylation differently by residues and that acetylation at K280 is a determinant of phosphorylation at some residues in the context of pathologic acetyltransferase activity. Yet, our results suggest there is a complex interplay yet to be explored between tau acetylation with tau phosphorylation.

Mechanisms of DNA damage-mediated neurotoxicity in neurodegenerative disease.

Neurons are highly susceptible to DNA damage accumulation due to their large energy requirements, elevated transcriptional activity, and long lifespan. While newer research has shown that DNA breaks and mutations may facilitate neuron diversity during development and neuronal function throughout life, a wealth of evidence indicates deficient DNA damage repair underlies many neurological disorders, especially age‐associated neurodegenerative diseases. Recently, efforts to clarify the molecular link between DNA damage and neurodegeneration have improved our understanding of how the genomic location of DNA damage and defunct repair proteins impact neuron health. Additionally, work establishing a role for senescence in the aging and diseased brain reveals DNA damage may play a central role in neuroinflammation associated with neurodegenerative disease.

Fukutin regulates tau phosphorylation and synaptic function: Novel properties of fukutin in neurons.

Fukutin, a product of the causative gene of Fukuyama congenital muscular dystrophy (FCMD), is known to be responsible for basement membrane formation. Patients with FCMD exhibit not only muscular dystrophy but also central nervous system abnormalities, including polymicrogyria and neurofibrillary tangles (NFTs) in the cerebral cortex. The formation of NFTs cannot be explained by basement membrane disorganization. To determine the involvement of fukutin in the NFT formation, we performed molecular pathological investigations using autopsied human brains and cultured neurons of a cell line (SH‐SY5Y). In human brains, NFTs, identified with an antibody against phosphorylated tau (p‐tau), were observed in FCMD patients but not age‐matched control subjects and were localized in cortical neurons lacking somatic immunoreactivity for glutamic acid decarboxylase (GAD), a marker of inhibitory neurons. In FCMD brains, NFTs were mainly distributed in lesions of polymicrogyria. Immunofluorescence staining revealed the colocalization of immunoreactivities for p‐tau and phosphorylated glycogen synthase kinase‐3β (GSK‐3β), a potential tau kinase, in the somatic cytoplasm of SH‐SY5Y cells; both the immunoreactivities were increased by fukutin knockdown and reduced by fukutin overexpression. Western blot analysis using SH‐SY5Y cells revealed consistent results. Enzyme‐linked immunosorbent assay (ELISA) confirmed the binding affinity of fukutin to tau and GSK‐3β in SH‐SY5Y cells. In the human brains, the density of GAD‐immunoreactive neurons in the frontal cortex was significantly higher in the FCMD group than in the control group. GAD immunoreactivity on Western blots of SH‐SY5Y cells was significantly increased by fukutin knockdown. On immunofluorescence staining, immunoreactivities for fukutin and GAD were colocalized in the somatic cytoplasm of the human brains and SH‐SY5Y cells, whereas those for fukutin and synaptophysin were colocalized in the neuropil of the human brains and the cytoplasm of SH‐SY5Y cells. ELISA confirmed the binding affinity of fukutin to GAD and synaptophysin in SH‐SY5Y cells. The present results provide in vivo and in vitro evidence for novel properties of fukutin as follows: (i) there is an inverse relationship between fukutin expression and GSK‐3β/tau phosphorylation in neurons; (ii) fukutin binds to GSK‐3β and tau; (iii) tau phosphorylation occurs in non‐GAD‐immunoreactive neurons in FCMD brains; (iv) neuronal GAD expression is upregulated in the absence of fukutin; and (v) fukutin binds to GAD and synaptophysin in presynaptic vesicles of neurons.

High Level Forebrain Expression of Active Tau Kinase p38γ Exacerbates Cognitive Dysfunction in Aged APP-transgenic Alzheimer’s Mice

Persistent improvement of cognitive deficits in Alzheimer’s disease (AD), a common form of dementia, is an unattained therapeutic objective. Gene therapy holds promise for treatment of familial and sporadic forms of AD. p38γ, a member of the p38 mitogen-activated protein (MAP) kinase family, inhibits amyloid-β toxicity through regulation of tau phosphorylation. We recently showed that a gene delivery approach increasing p38γ resulted in markedly better learning and memory performance in mouse models of AD at advanced stages of amyloid-β- and tau-mediated cognitive impairment. Notably, low-to-moderate expression of p38γ had beneficial outcomes on cognition. The impact of high levels of p38γ on neuronal function remain unclear. Therefore, we addressed the outcomes of high levels of active p38γ on brain function, by direct injection of p38γ-encoding adeno-associated virus (AAV) into the forebrain of aged mice of an APP transgenic AD mouse model. While motor function in p38γ-expressing APP transgenic mice 2 months post-injection was comparable to control treated APP mice, their activity was markedly reduced in the open field test and included frequent bouts of immobility. Moreover, their learning and memory function was markedly impaired compared to control-treated aged APP mice. These results suggest that high neuronal levels of active p38γ emphasize a stress kinase role of p38γ, perturbing circuit function in motivation, navigation, and spatial learning. Overall, this work shows excessive neuronal p38γ levels can aggravate circuit dysfunction and advises adjustable expression systems will be required for sustainable AD gene therapy based on p38γ activity.

Therapeutic Mechanism and Key Alkaloids of Uncaria rhynchophylla in Alzheimer's Disease From the Perspective of Pathophysiological Processes.

Presently, there is a lack of effective disease-modifying drugs for the treatment of Alzheimer’s disease (AD). Uncaria rhynchophylla (UR) and its predominant active phytochemicals alkaloids have been studied to treat AD. This study used a novel network pharmacology strategy to identify UR alkaloids against AD from the perspective of AD pathophysiological processes and identified the key alkaloids for specific pathological process. The analysis identified 10 alkaloids from UR based on high-performance liquid chromatography (HPLC) that corresponded to 127 targets correlated with amyloid-β (Aβ) pathology, tau pathology and Alzheimer disease pathway. Based on the number of targets correlated with AD pathophysiological processes, angustoline, angustidine, corynoxine and isocorynoxeine are highly likely to become key phytochemicals in AD treatment. Among the 127 targets, JUN, STAT3, MAPK3, CCND1, MMP2, MAPK8, GSK3B, JAK3, LCK, CCR5, CDK5 and GRIN2B were identified as core targets. Based on the pathological process of AD, angustoline, angustidine and isocorynoxeine were identified as the key UR alkaloids regulating Aβ production and corynoxine, isocorynoxeine, dihydrocorynatheine, isorhynchophylline and hirsutine were identified as key alkaloids that regulate tau phosphorylation. The findings of this study contribute to a more comprehensive understanding of the key alkaloids and mechanisms of UR in the treatment of AD, as well as provide candidate compounds for drug research and development for specific AD pathological processes.

IL-6 and IL-1β upregulation and tau protein phosphorylation in response to chronic alcohol exposure in the mouse hippocampus.

Alcoholism and alcohol abuse can lead to memory loss and cognitive dysfunction. The neuroinflammatory response plays an important role in the neurotoxic mechanism of chronic alcohol exposure. Additionally, the phosphorylation status of the tau protein is closely related to neurotoxicity and synaptic function. As inflammatory cytokines have been shown to regulate tau phosphorylation, in the present study, the aim was to determine whether cognitive impairment caused by chronic alcohol exposure is associated with neuroinflammation and tau hyperphosphorylation in the hippocampus. We established a chronic alcohol exposure model of C57BL/6J mice. The Y maze was used to assess the spatial recognition ability of mice, and ELISA was used to detect the levels of inflammatory cytokines IL-1β and IL-6 in the serum. Immunohistochemical and western blot assays were used to assess the expression levels of IL-1β and IL-6, as well as tau protein and its phosphorylation status in the hippocampus. We also analyzed the mRNA and protein expression of the synapse-associated proteins PSD95 and synaptophysin in the hippocampus. Our results showed that chronic alcohol exposure impaired the spatial recognition ability of mice upregulated the expression of IL-1β and IL-6 in the serum and hippocampus and increased the phosphorylation of tau protein in the hippocampus. In addition, chronic alcohol exposure downregulated PSD95 and synaptophysin protein levels. The present results indicate that hippocampal IL-1β, IL-6, and phosphorylated tau proteins may be involved in the neurotoxic mechanism of chronic alcohol exposure by mediating synaptic dysfunction.

Downregulation of glob1 suppresses pathogenesis of human neuronal tauopathies in Drosophila by regulating tau phosphorylation and ROS generation

Human tauopathies represent a group of neurodegenerative disorders, characterized by abnormal hyperphosphorylation and aggregation of tau protein, which ultimately cause neurodegeneration. The aberrant tau hyperphosphorylation is mostly attributed to the kinases/phosphatases imbalance, which is majorly contributed by the generation of reactive oxygen species (ROS). Globin(s) represent a well-conserved group of proteins which are involved in O2 management, regulation of cellular ROS in different cell types. Similarly, Drosophila globin1 (a homologue of human globin) with its known roles in oxygen management and development of nervous system exhibits striking similarities with the mammalian neuroglobin. Several recent evidences support the hypothesis that neuroglobins are associated with Alzheimer's disease pathogenesis. We herein noted that targeted expression of human-tau induces the cellular level of Glob1 protein in Drosophila tauopathy models. Subsequently, RNAi mediated restored level of Glob1 restricts the pathogenic effect of human-tau by minimizing its hyperphosphorylation via GSK-3β/p-Akt and p-JNK pathways. In addition, it also activates the Nrf2-keap1-ARE cascade to stabilize the tau-mediated increased level of ROS. These two parallel cellular events provide a significant rescue against human tau-mediated neurotoxicity in the fly models. For the first time we report a direct involvement of an oxygen sensing globin gene in tau etiology. In view of the fact that human genome encodes for the multiple Globin proteins including a nervous system specific neuroglobin; and therefore, our findings may pave the way to investigate if the conserved oxygen sensing globin gene(s) can be exploited in devising novel therapeutic strategies against tauopathies.

Electroacupuncture Protects Cognition by Regulating Tau Phosphorylation and Glucose Metabolism via the AKT/GSK3β Signaling Pathway in Alzheimer's Disease Model Mice.

BackgroundAlzheimer’s disease (AD) is mainly manifested as a continuous and progressive decline in cognitive ability. Neurofibrillary tangles (NFTs) are pathological hallmarks of AD and due to accumulated phosphorylated Tau. Glycogen synthase kinase-3β (GSK3β), as a major Tau kinase and a downstream target of the serine protein kinase B (AKT) signaling pathway, can regulate Tau phosphorylation in AD. Importantly, the AKT/GSK3β signaling pathway is involved in glucose metabolism, and abnormal glucose metabolism is found in the AD brain. Numerous studies have shown that electroacupuncture (EA), which is thought to be a potential complementary therapeutic approach for AD, can protect cognitive ability to a certain extent.ObjectiveThe purpose of this experiment was to investigate whether the protective and beneficial mechanism of EA on cognition was mediated by the AKT/GSK3β signaling pathway, thereby improving glucose metabolism and Tau phosphorylation in the brain.MethodsEA was applied to the Baihui (GV20) and Yintang (GV29) acupoints of 6-month-old amyloid precursor protein (APP)/presenilin-1 (PS1) mice for 20 min, and then quickly prick Shuigou (GV26) acupoint. The intervention was performed once every other day for 28 days. The Morris water maze (MWM) test was performed on C57BL/6N (Non-Tg) mice, APP/PS1 (Tg) mice and EA-treated Tg (Tg + EA) mice to evaluate the effect of EA therapy on cognitive function. 18F-FDG positron emission tomography (PET), immunohistochemistry, and western blotting (WB) were used to investigate the possible mechanism underlying the effect of EA on AD.ResultsEA treatment significantly improved the cognition of APP/PS1 mice and the glucose uptake rate in the hippocampus. Furthermore, EA inhibited the phosphorylation of Tau (Ser199 and Ser202) proteins by inducing AKT (Ser473) and GSK3β (Ser9) phosphorylation.ConclusionThese results demonstrate that EA intervention protects cognition by enhancing glucose metabolism and inhibiting abnormal phosphorylation of Tau protein in the AD model mice, and the AKT/GSK3β pathway might play an irreplaceable role in the regulation process.