Role of Tau as a Microtubule-Associated Protein: Structural and Functional Aspects

Transition Metal Complexes as Therapeutics: A New Frontier in Combatting Neurodegenerative Disorders through Protein Aggregation Modulation

Neurodegenerative disorders (NDDs) are a class of debilitating diseases that progressively impair the protein structure and result in neurological dysfunction in the nervous system. Among these disorders, Alzheimer's disease (AD), prion diseases such as Creutzfeldt-Jakob disease (CJD), and Parkinson's disease (PD) are caused by protein misfolding and aggregation at the cellular level. In recent years, transition metal complexes have gained significant attention for their potential applications in diagnosing, imaging, and curing these NDDs. These complexes have intriguing possibilities as therapeutics due to their diverse ligand systems and chemical properties and can interact with biological systems with minimal detrimental effects. This review focuses on the recent progress in transition metal therapeutics as a new era of hope in the battle against AD, CJD, and PD by modulating protein aggregation in vitro and in vivo. It may shed revolutionary insights into unlocking new opportunities for researchers to develop metal-based drugs to combat NDDs.

Brain Microvascular Pericyte Pathology Linking Alzheimer's Disease to Diabetes

The brain microvasculature, which delivers oxygen and nutrients and forms a critical barrier protecting the central nervous system via capillaries, is deleteriously affected by both Alzheimer's disease (AD) and type 2 diabetes (T2D). T2D patients have an increased risk of developing AD, suggesting potentially related microvascular pathological mechanisms. Pericytes are an ideal cell type to study for functional links between AD and T2D. These specialized capillary-enwrapping cells regulate capillary density, lumen diameter, and blood flow. Pericytes also maintain endothelial tight junctions to ensure blood-brain barrier integrity, modulation of immune cell extravasation, and clearance of toxins. Changes in these phenomena have been observed in both AD and T2D, implicating "pericyte pathology" as a common feature of AD and T2D. This review examines the mechanisms of AD and T2D from the perspective of the brain microvasculature, highlighting how pericyte pathology contributes to both diseases. Our review identifies voids in understanding how AD and T2D negatively impact the brain microvasculature and suggests future studies to examine the intersections of these diseases.

KIF2C/MCAK a prognostic biomarker and its oncogenic potential in malignant progression, and prognosis of cancer patients: a systematic review and meta-analysis as biomarker

KIF2C/MCAK (KIF2C) is the most well-characterized member of the kinesin-13 family, which is critical in the regulation of microtubule (MT) dynamics during mitosis, as well as interphase. This systematic review briefly describes the important structural elements of KIF2C, its regulation by multiple molecular mechanisms, and its broad cellular functions. Furthermore, it systematically summarizes its oncogenic potential in malignant progression and performs a meta-analysis of its prognostic value in cancer patients. KIF2C was shown to be involved in multiple crucial cellular processes including cell migration and invasion, DNA repair, senescence induction and immune modulation, which are all known to be critical during the development of malignant tumors. Indeed, an increasing number of publications indicate that KIF2C is aberrantly expressed in multiple cancer entities. Consequently, we have highlighted its involvement in at least five hallmarks of cancer, namely: genome instability, resisting cell death, activating invasion and metastasis, avoiding immune destruction and cellular senescence. This was followed by a systematic search of KIF2C/MCAK's expression in various malignant tumor entities and its correlation with clinicopathologic features. Available data were pooled into multiple weighted meta-analyses for the correlation between KIF2Chigh protein or gene expression and the overall survival in breast cancer, non-small cell lung cancer and hepatocellular carcinoma patients. Furthermore, high expression of KIF2C was correlated to disease-free survival of hepatocellular carcinoma. All meta-analyses showed poor prognosis for cancer patients with KIF2Chigh expression, associated with a decreased overall survival and reduced disease-free survival, indicating KIF2C's oncogenic potential in malignant progression and as a prognostic marker. This work delineated the promising research perspective of KIF2C with modern in vivo and in vitro technologies to further decipher the function of KIF2C in malignant tumor development and progression. This might help to establish KIF2C as a biomarker for the diagnosis or evaluation of at least three cancer entities.

How do neurons age? A focused review on the aging of the microtubular cytoskeleton

Aging is the leading risk factor for Alzheimer's disease and other neurodegenerative diseases. We now understand that a breakdown in the neuronal cytoskeleton, mainly underpinned by protein modifications leading to the destabilization of microtubules, is central to the pathogenesis of Alzheimer's disease. This is accompanied by morphological defects across the somatodendritic compartment, axon, and synapse. However, knowledge of what occurs to the microtubule cytoskeleton and morphology of the neuron during physiological aging is comparatively poor. Several recent studies have suggested that there is an age-related increase in the phosphorylation of the key microtubule stabilizing protein tau, a modification, which is known to destabilize the cytoskeleton in Alzheimer's disease. This indicates that the cytoskeleton and potentially other neuronal structures reliant on the cytoskeleton become functionally compromised during normal physiological aging. The current literature shows age-related reductions in synaptic spine density and shifts in synaptic spine conformation which might explain age-related synaptic functional deficits. However, knowledge of what occurs to the microtubular and actin cytoskeleton, with increasing age is extremely limited. When considering the somatodendritic compartment, a regression in dendrites and loss of dendritic length and volume is reported whilst a reduction in soma volume/size is often seen. However, research into cytoskeletal change is limited to a handful of studies demonstrating reductions in and mislocalizations of microtubule-associated proteins with just one study directly exploring the integrity of the microtubules. In the axon, an increase in axonal diameter and age-related appearance of swellings is reported but like the dendrites, just one study investigates the microtubules directly with others reporting loss or mislocalization of microtubule-associated proteins. Though these are the general trends reported, there are clear disparities between model organisms and brain regions that are worthy of further investigation. Additionally, longitudinal studies of neuronal/cytoskeletal aging should also investigate whether these age-related changes contribute not just to vulnerability to disease but also to the decline in nervous system function and behavioral output that all organisms experience. This will highlight the utility, if any, of cytoskeletal fortification for the promotion of healthy neuronal aging and potential protection against age-related neurodegenerative disease. This review seeks to summarize what is currently known about the physiological aging of the neuron and microtubular cytoskeleton in the hope of uncovering mechanisms underpinning age-related risk to disease.

nP-Collabs: Investigating Counterion-Mediated Bridges in the Multiply Phosphorylated Tau-R2 Repeat

Tau is an intrinsically disordered (IDP) microtubule-associated protein (MAP) that plays a key part in microtubule assembly and organization. The function of tau can be regulated by multiple phosphorylation sites. These post-translational modifications are known to decrease the binding affinity of tau for microtubules, and abnormal tau phosphorylation patterns are involved in Alzheimer's disease. Using all-atom molecular dynamics simulations, we compared the conformational landscapes explored by the tau R2 repeat domain (which comprises a strong tubulin binding site) in its native state and with multiple phosphorylations on the S285, S289, and S293 residues, with four different standard force field (FF)/water model combinations. We find that the different parameters used for the phosphate groups (which can be more or less flexible) in these FFs and the specific interactions between bulk cations and water lead to the formation of a specific type of counterion bridge, termed nP-collab (for nphosphate collaboration, with n being an integer), where counterions form stable structures binding with two or three phosphate groups simultaneously. The resulting effect of nP-collabs on the tau-R2 conformational space differs when using sodium or potassium cations and is likely to impact the peptide overall dynamics and how this MAP interacts with tubulins. We also investigated the effect of phosphoresidue spacing and ionic concentration by modeling polyalanine peptides containing two phosphoserines located one-six residues apart. Three new metrics specifically tailored for IDPs (proteic Menger curvature, local curvature, and local flexibility) were introduced, which allow us to fully characterize the impact of nP-collabs on the dynamics of disordered peptides at the residue level.

Tau is required for glial lipid droplet formation and resistance to neuronal oxidative stress

The accumulation of reactive oxygen species (ROS) is a common feature of tauopathies, defined by Tau accumulations in neurons and glia. High ROS in neurons causes lipid production and the export of toxic peroxidated lipids (LPOs). Glia uptake these LPOs and incorporate them into lipid droplets (LDs) for storage and catabolism. We found that overexpressing Tau in glia disrupts LDs in flies and rat neuron-astrocyte co-cultures, sensitizing the glia to toxic, neuronal LPOs. Using a new fly tau loss-of-function allele and RNA-mediated interference, we found that endogenous Tau is required for glial LD formation and protection against neuronal LPOs. Similarly, endogenous Tau is required in rat astrocytes and human oligodendrocyte-like cells for LD formation and the breakdown of LPOs. Behaviorally, flies lacking glial Tau have decreased lifespans and motor defects that are rescuable by administering the antioxidant N-acetylcysteine amide. Overall, this work provides insights into the important role that Tau has in glia to mitigate ROS in the brain.

Intermediate filaments at a glance

Intermediate filaments (IFs) comprise a large family of versatile cytoskeletal proteins, divided into six subtypes with tissue-specific expression patterns. IFs have a wide repertoire of cellular functions, including providing structural support to cells, as well as active roles in mechanical support and signaling pathways. Consequently, defects in IFs are associated with more than 100 diseases. In this Cell Science at a Glance article, we discuss the established classes of IFs and their general features, their functions beyond structural support, and recent advances in the field. We also highlight their involvement in disease and potential use as clinical markers of pathological conditions. Finally, we provide our view on current knowledge gaps and the future directions of the IF field.

Multiple Transcriptomic Analyses Explore Potential Synaptic Biomarker Rabphilin-3A for Alzheimer's Disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder afflicting the elderly population worldwide. The identification of potential gene candidates for AD holds promises for diagnostic biomarkers and therapeutic targets. Employing a comprehensive strategy, this study integrated transcriptomic data from diverse data sources, including microarray and single-cell datasets from blood and tissue samples, enabling a detailed exploration of gene expression dynamics. Through this thorough investigation, 19 notable candidate genes were found with consistent expression changes across both blood and tissue datasets, suggesting their potential as biomarkers for AD. In addition, single cell sequencing analysis further highlighted their specific expression in excitatory and inhibitory neurons, the primary functional units in the brain, underscoring their relevance to AD pathology. Moreover, the functional enrichment analysis revealed that three of the candidate genes were downregulated in synaptic signaling pathway. Further validation experiments significantly showed reduced levels of rabphilin-3A (RPH3A) in 3xTg-AD model mice, implying its role in disease pathogenesis. Given its role in neurotransmitter exocytosis and synaptic function, further investigation into RPH3A and its interactions with neurotrophic proteins may provide valuable insights into the complex molecular mechanisms underlying synaptic dysfunction in AD.

Tau in neurodegenerative diseases: molecular mechanisms, biomarkers, and therapeutic strategies

The deposition of abnormal tau protein is characteristic of Alzheimer's disease (AD) and a class of neurodegenerative diseases called tauopathies. Physiologically, tau maintains an intrinsically disordered structure and plays diverse roles in neurons. Pathologically, tau undergoes abnormal post-translational modifications and forms oligomers or fibrous aggregates in tauopathies. In this review, we briefly introduce several tauopathies and discuss the mechanisms mediating tau aggregation and propagation. We also describe the toxicity of tau pathology. Finally, we explore the early diagnostic biomarkers and treatments targeting tau. Although some encouraging results have been achieved in animal experiments and preclinical studies, there is still no cure for tauopathies. More in-depth basic and clinical research on the pathogenesis of tauopathies is necessary.

Complement receptor 4 mediates the clearance of extracellular tau fibrils by microglia

Tauopathies exhibit a characteristic accumulation of misfolded tau aggregates in the brain. Tau pathology shows disease-specific spatiotemporal propagation through intercellular transmission, which is closely correlated with the progression of clinical manifestations. Therefore, identifying molecular mechanisms that prevent tau propagation is critical for developing therapeutic strategies for tauopathies. The various innate immune receptors, such as complement receptor 3 (CR3) and complement receptor 4 (CR4), have been reported to play a critical role in the clearance of various extracellular toxic molecules by microglia. However, their role in tau clearance has not been studied yet. In the present study, we investigated the role of CR3 and CR4 in regulating extracellular tau clearance. We found that CR4 selectively binds to tau fibrils but not to tau monomers, whereas CR3 does not bind to either of them. Inhibiting CR4, but not CR3, significantly reduces the uptake of tau fibrils by BV2 cells and primary microglia. By contrast, inhibiting CR4 has no effect on the uptake of tau monomers by BV2 cells. Furthermore, inhibiting CR4 suppresses the clearance of extracellular tau fibrils, leading to more seed-competent tau fibrils remaining in the extracellular space relative to control samples. We also provide evidence that the expression of CR4 is upregulated in the brains of human Alzheimer's disease patients and the PS19 mouse model of tauopathy. Taken together, our data strongly support that CR4 is a previously undescribed receptor for the clearance of tau fibrils in microglia and may represent a novel therapeutic target for tauopathy.

Modulation of cholesterol metabolism with Phytoremedies in Alzheimer's disease: A comprehensive review

Alzheimer's disease (AD) is a complex neurological ailment that causes cognitive decline and memory loss. Cholesterol metabolism dysregulation has emerged as a crucial element in AD pathogenesis, contributing to the formation of amyloid-beta (Aβ) plaques and tau tangles, the disease's hallmark neuropathological characteristics. Thus, targeting cholesterol metabolism has gained attention as a potential therapeutic method for Alzheimer's disease. Phytoremedies, which are generated from plants and herbs, have shown promise as an attainable therapeutic option for Alzheimer's disease. These remedies contain bioactive compounds like phytochemicals, flavonoids, and polyphenols, which have demonstrated potential in modulating cholesterol metabolism and related pathways. This comprehensive review explores the modulation of cholesterol metabolism by phytoremedies in AD. It delves into the role of cholesterol in brain function, highlighting disruptions observed in AD. Additionally, it examines the underlying molecular mechanisms of cholesterol-related pathology in AD. The review emphasizes the significance of phytoremedies as a potential therapeutic intervention for AD. It discusses the drawbacks of current treatments and the need for alternative strategies addressing cholesterol dysregulation and its consequences. Through an in-depth analysis of specific phytoremedies, the review presents compelling evidence of their potential benefits. Molecular mechanisms underlying phytoremedy effects on cholesterol metabolism are examined, including regulation of cholesterol-related pathways, interactions with Aβ pathology, influence on tau pathology, and anti-inflammatory effects. The review also highlights challenges and future perspectives, emphasizing standardization, clinical evidence, and personalized medicine approaches to maximize therapeutic potential in AD treatment. Overall, phytoremedies offer promise as a potential avenue for AD management, but further research and collaboration are necessary to fully explore their efficacy, safety, and mechanisms of action.

Nanotechnology for tau pathology in Alzheimer's disease

Tau protein aggregation is a defining characteristic of Alzheimer's disease (AD), leading to the formation of neurofibrillary tangles that disrupt neural communication and ultimately result in cognitive decline. Nanotechnology presents novel strategies for both diagnosing and treating Alzheimer's disease. Nanotechnology. It has become a revolutionary tool in the fight against Alzheimer's disease, particularly in addressing the pathological accumulation of tau protein. This review explores the relationship between tau-related neurophysiology and the utilization of nanotechnology for AD treatment, focusing on the application of nanomaterials to regulate tau phosphorylation, hinder tau aggregation and propagation, stabilize microtubules, eliminate pathological tau and emphasize the potential of nanotechnology in developing personalized therapies and monitoring treatment responses in AD patients. This review combines tau-related neurophysiology with nanotechnology to provide new insights for further understanding and treating Alzheimer's disease.

Epigenetic Mechanisms of Aluminum-Induced Neurotoxicity and Alzheimer's Disease: A Focus on Non-Coding RNAs

Aluminum (Al) is known to induce neurotoxic effects, potentially contributing to Alzheimer's disease (AD) pathogenesis. Recent studies suggest that epigenetic modification may contribute to Al neurotoxicity, although the mechanisms are still debatable. Therefore, the objective of the present study was to summarize existing data on the involvement of epigenetic mechanisms in Al-induced neurotoxicity, especially AD-type pathology. Existing data demonstrate that Al exposure induces disruption in DNA methylation, histone modifications, and non-coding RNA expression in brains. Alterations in DNA methylation following Al exposure were shown to be mediated by changes in expression and activity of DNA methyltransferases (DNMTs) and ten-eleven translocation proteins (TETs). Al exposure was shown to reduce histone acetylation by up-regulating expression of histone deacetylases (HDACs) and impair histone methylation, ultimately contributing to down-regulation of brain-derived neurotrophic factor (BDNF) expression and activation of nuclear factor κB (NF-κB) signaling. Neurotoxic effects of Al exposure were also associated with aberrant expression of non-coding RNAs, especially microRNAs (miR). Al-induced patterns of miR expression were involved in development of AD-type pathology by increasing amyloid β (Aβ) production through up-regulation of Aβ precursor protein (APP) and β secretase (BACE1) expression (down-regulation of miR-29a/b, miR-101, miR-124, and Let-7c expression), increasing in neuroinflammation through NF-κB signaling (up-regulation of miR-9, miR-125b, miR-128, and 146a), as well as modulating other signaling pathways. Furthermore, reduced global DNA methylation, altered histone modification, and aberrant miRNA expression were associated with cognitive decline in Al-exposed subjects. However, further studies are required to evaluate the contribution of epigenetic mechanisms to Al-induced neurotoxicity and/or AD development.

Intracellular tau fragment droplets serve as seeds for tau fibrils

Intracellular tau aggregation requires a local protein concentration increase, referred to as "droplets". However, the cellular mechanism for droplet formation is poorly understood. Here, we expressed OptoTau, a P301L mutant tau fused with CRY2olig, a light-sensitive protein that can form homo-oligomers. Under blue light exposure, OptoTau increased tau phosphorylation and was sequestered in aggresomes. Suppressing aggresome formation by nocodazole formed tau granular clusters in the cytoplasm. The granular clusters disappeared by discontinuing blue light exposure or 1,6-hexanediol treatment suggesting that intracellular tau droplet formation requires microtubule collapse. Expressing OptoTau-ΔN, a species of N-terminal cleaved tau observed in the Alzheimer's disease brain, formed 1,6-hexanediol and detergent-resistant tau clusters in the cytoplasm with blue light stimulation. These intracellular stable tau clusters acted as a seed for tau fibrils in vitro. These results suggest that tau droplet formation and N-terminal cleavage are necessary for neurofibrillary tangles formation in neurodegenerative diseases.

Genomic stress and impaired DNA repair in Alzheimer disease

Alzheimer disease (AD) is the most prominent form of dementia and has received considerable attention due to its growing burden on economic, healthcare and basic societal infrastructures. The two major neuropathological hallmarks of AD, i.e., extracellular amyloid beta (Aβ) peptide plaques and intracellular hyperphosphorylated Tau neurofibrillary tangles, have been the focus of much research, with an eye on understanding underlying disease mechanisms and identifying novel therapeutic avenues. One often overlooked aspect of AD is how Aβ and Tau may, through indirect and direct mechanisms, affect genome integrity. Herein, we review evidence that Aβ and Tau abnormalities induce excessive genomic stress and impair genome maintenance mechanisms, events that can promote DNA damage-induced neuronal cell loss and associated brain atrophy.

Tau modulation through AAV9 therapy augments Akt/Erk survival signalling in glaucoma mitigating the retinal degenerative phenotype

The microtubule-associated protein Tau is a key player in various neurodegenerative conditions, including Alzheimer's disease (AD) and Tauopathies, where its hyperphosphorylation disrupts neuronal microtubular lattice stability. Glaucoma, a neurodegenerative disorder affecting the retina, leads to irreversible vision loss by damaging retinal ganglion cells and the optic nerve, often associated with increased intraocular pressure. Prior studies have indicated Tau expression and phosphorylation alterations in the retina in both AD and glaucoma, yet the causative or downstream nature of Tau protein changes in these pathologies remains unclear. This study investigates the impact of Tau protein modulation on retinal neurons under normal and experimental glaucoma conditions. Employing AAV9-mediated gene therapy for Tau overexpression and knockdown, both manipulations were found to adversely affect retinal structural and functional measures as well as neuroprotective Akt/Erk survival signalling in healthy conditions. In the experimental glaucoma model, Tau overexpression intensified inner retinal degeneration, while Tau silencing provided significant protection against these degenerative changes. These findings underscore the critical role of endogenous Tau protein levels in preserving retinal integrity and emphasize the therapeutic potential of targeting Tau in glaucoma pathology.

Loss of cytidine deaminase expression as a potential attempt to counteract the process of carcinogenesis by reducing basal PARP-1 activity and increasing tau levels

Cytidine deaminase (CDA) is a pyrimidine salvage pathway enzyme that catalyzes the hydrolytic deamination of free cytidine and deoxycytidine to uridine and deoxyuridine, respectively. Our team discovered that CDA deficiency is associated with several aspects of genetic instability, such as increased sister chromatid exchange and ultrafine anaphase bridge frequencies. Based on these results, we sought (1) to determine how CDA deficiency contributes to genetic instability, (2) to explore the possible relationships between CDA deficiency and carcinogenesis, and (3) to develop a new anticancer treatment targeting CDA-deficient tumors. This review summarizes our major findings indicating that CDA deficiency is associated with a genetic instability that does not confer an increased cancer risk. In light of our results and published data, I propose a novel hypothesis that loss of CDA, by reducing basal PARP-1 activity and increasing Tau levels, may reflect an attempt to prevent, slow or reverse the process of carcinogenesis.

Arabidopsis hypocotyl growth in darkness requires the phosphorylation of a microtubule-associated protein

Rapid hypocotyl elongation allows buried seedlings to emerge, where light triggers de-etiolation and inhibits hypocotyl growth mainly by photoreceptors. Phosphorylation/dephosphorylation events regulate many aspects of plant development. Only recently we have begun to uncover the earliest phospho-signaling responders to light. Here, we reported a large-scale phosphoproteomic analysis and identified 20 proteins that changed their phosphorylation pattern following a 20 min light pulse compared to darkness. Microtubule-associated proteins were highly overrepresented in this group. Among them, we studied CIP7 (COP1-INTERACTING-PROTEIN 7), which presented microtubule (MT) localization in contrast to the previous description. An isoform of CIP7 phosphorylated at Serine915 was detected in etiolated seedlings but was undetectable after a light pulse in the presence of photoreceptors, while CIP7 transcript expression decays with long light exposure. The short hypocotyl phenotype and rearrangement of MTs in etiolated cip7 mutants are complemented by CIP7-YFP and the phospho-mimetic CIP7S915D-YFP, but not the phospho-null CIP7S915A-YFP suggesting that the phosphorylated S915CIP7 isoform promotes hypocotyl elongation through MT reorganization in darkness. Our evidence on Serine915 of CIP7 unveils phospho-regulation of MT-based processes during skotomorphogenic hypocotyl growth.

Effects of heterologous human tau protein expression in yeast models of proteotoxic stress response

BACKGROUND

The primary histological characteristic of Alzheimer's disease is the presence of neurofibrillary tangles, which are large aggregates of tau protein. Aging is the primary risk factor for the development of Alzheimer's disease, however, the underlying causes of tau protein aggregation and toxicity are unclear.

AIMS

Here we investigated tau aggregation and toxicity under the conditions of compromised protein homeostasis.

METHODS

We used heterologous expression of human tau protein in the unicellular eukaryote yeast Saccharomyces cerevisiae with evolutionarily conserved protein quality control pathways and examined tau-dependent toxicity and aggregation using growth assays, fluorescence microscopy, and a split luciferase-based reporter NanoBiT.

RESULTS

Tau protein expressed in yeast under mild proteotoxic stress, or in mutants with impaired pathways for proteotoxic stress response, did not lead to synthetic toxicity or the formation of obvious aggregates. Chronologically old cells also did not develop observable tau aggregates. Our examination of tau oligomerization in living cells using NanoBiT reporter suggests that tau does not form significant levels of oligomers under basal conditions or under mild proteotoxic stress.

CONCLUSION

Together our data suggest that human tau protein does not represent a major burden to the protein quality control system in yeast cells.

Biomarkers in Acute Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Traumatic brain injury (TBI) stands as a significant contributor to traumatic death and disability worldwide. In recent years, researchers have identified biomarkers to gauge useful outcomes in TBI patients. However, the enigma of timely sample collection to measure the biomarkers remains a controversial point in the case of TBI, unlike other degenerative diseases like Alzheimer's disease and Parkinson's disease, where we can collect the sample at any point in time. The purpose of this study is to evaluate the sensitivity of biomarkers in TBI concerning time of injury by analyzing recent available data on biomarkers in the medical literature. A total of 2,256 studies were initially retrieved from the search engine. After an initial screening, only 1,750 unique articles remained. After excluding review articles, animal studies, meta-analysis, and studies with children (screened by title and abstract), 30 kinds of literature were found relevant to search the required variables. Further 16 studies were excluded due to the nonavailability of complete variables or data. Finally, 14 studies remained and were included in the analysis. This study has analyzed the four most commonly described biomarkers for TBI in the literature: glial fibrillary acidic protein (GFAP), S100 calcium-binding protein B, ubiquitin carboxy-terminal hydrolase L1, and Tau. According to this statistical analysis, all biomarkers included in the study have shown their serum levels after trauma. So, all these biomarkers can be used for further study in the outcome prediction and diagnosis of TBI patients. The meta-analysis suggests that the best biomarker for TBI is Tau in cases where sample collection is done within 24 hours, while GFAP is the best biomarker to be studied for TBI if sample collection is done 24 hours after trauma.

Amyloid-beta and tau protein beyond Alzheimer's disease

ABSTRACT

The aggregation of amyloid-beta peptide and tau protein dysregulation are implicated to play key roles in Alzheimer's disease pathogenesis and are considered the main pathological hallmarks of this devastating disease. Physiologically, these two proteins are produced and expressed within the normal human body. However, under pathological conditions, abnormal expression, post-translational modifications, conformational changes, and truncation can make these proteins prone to aggregation, triggering specific disease-related cascades. Recent studies have indicated associations between aberrant behavior of amyloid-beta and tau proteins and various neurological diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as retinal neurodegenerative diseases like Glaucoma and age-related macular degeneration. Additionally, these proteins have been linked to cardiovascular disease, cancer, traumatic brain injury, and diabetes, which are all leading causes of morbidity and mortality. In this comprehensive review, we provide an overview of the connections between amyloid-beta and tau proteins and a spectrum of disorders.

Effect and Potential Mechanism of Immunotherapy on Cognitive Deficits in Animal Models of Alzheimer's Disease: A Systematic Review and Meta-Analysis

OBJECTIVE

Immunotherapy has been reported to ameliorate Alzheimer's disease (AD) in the animal model; however, the immunologic approaches and mechanisms have not been specifically described. Thus, the systematic review and meta-analysis were conducted to explore the effect and potential mechanism of immunotherapy on AD animal experiments based on behavioral indicators.

METHODS

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and the Cochrane Collaboration guidelines and the inclusion/exclusion criteria of immunotherapy in animal studies, 15 studies were systematically reviewed after extraction from a collected database of 3,742 publications. Finally, the effect and mechanism of immunotherapy on AD models were described by performing multiple subgroup analyses.

RESULTS

After immunotherapy, the escape latency was reduced by 18.15 seconds and the number of crossings over the platform location was increased by 1.60 times in the Morris Water Maze. Furthermore, compared to the control group, active and passive immunization could markedly ameliorate learning and memory impairment in 3 × Tg AD animal models, and active immunization could ameliorate the learning and memory ability of the APPswe/PS1ΔE9 AD animal model. Meanwhile, it could be speculated that cognitive dysfunction was improved by immunotherapy, perhaps mainly via reducing Aβ40, Aβ42, and Tau levels, as well as increasing IL-4 levels.

CONCLUSION

Immunotherapy significantly ameliorated the cognitive dysfunction of AD animal models by assessing behavioral indicators.

Amyloid-β and Phosphorylated Tau are the Key Biomarkers and Predictors of Alzheimer's Disease

Alzheimer's disease (AD) is a age-related neurodegenerative disease and is a major public health concern both in Texas, US and Worldwide. This neurodegenerative disease is mainly characterized by amyloid-beta (Aβ) and phosphorylated Tau (p-Tau) accumulation in the brains of patients with AD and increasing evidence suggests that these are key biomarkers in AD. Both Aβ and p-tau can be detected through various imaging techniques (such as positron emission tomography, PET) and cerebrospinal fluid (CSF) analysis. The presence of these biomarkers in individuals, who are asymptomatic or have mild cognitive impairment can indicate an increased risk of developing AD in the future. Furthermore, the combination of Aβ and p-tau biomarkers is often used for more accurate diagnosis and prediction of AD progression. Along with AD being a neurodegenerative disease, it is associated with other chronic conditions such as cardiovascular disease, obesity, depression, and diabetes because studies have shown that these comorbid conditions make people more vulnerable to AD. In the first part of this review, we discuss that biofluid-based biomarkers such as Aβ, p-Tau in cerebrospinal fluid (CSF) and Aβ & p-Tau in plasma could be used as an alternative sensitive technique to diagnose AD. In the second part, we discuss the underlying molecular mechanisms of chronic conditions linked with AD and how they affect the patients in clinical care.

Changes in Oxidised Phospholipids in Response to Oxidative Stress in Microtubule-Associated Protein Tau (MAPT) Mutant Dopamine Neurons

Microtubule-associated protein Tau (MAPT) is strongly associated with the development of neurodegenerative diseases. In addition to driving the formation of neurofibrillary tangles (NFT), mutations in the MAPT gene can also cause oxidative stress through hyperpolarisation of the mitochondria. This study explores the impact that MAPT mutation is having on phospholipid metabolism in iPSC-derived dopamine neurons, and to determine if these effects are exacerbated by mitochondrial and endoplasmic reticulum stress. Neurons that possessed a mutated copy of MAPT were shown to have significantly higher levels of oxo-phospholipids (Oxo-PL) than wild-type neurons. Oxidation of the hydrophobic fatty acid side chains changes the chemistry of the phospholipid leading to disruption of membrane function and potential cell lysis. In wild-type neurons, both mitochondrial and endoplasmic reticulum stress increased Oxo-PL abundance; however, in MAPT mutant neurons mitochondrial stress appeared to have a minimal effect. Endoplasmic reticulum stress, surprisingly, reduced the abundance of Oxo-PL in MAPT mutant dopamine neurons, and we postulate that this reduction could be modulated through hyperactivation of the unfolded protein response and X-box binding protein 1. Overall, the results of this study contribute to furthering our understanding of the regulation and impact of oxidative stress in Parkinson's disease pathology.

Prenylated Flavanone Isolated from Dalea Species as a Potential Multitarget-Neuroprotector in an In Vitro Alzheimer's Disease Mice Model

Alzheimer's disease (AD) involves a neurodegenerative process that has not yet been prevented, reversed, or stopped. Continuing with the search for natural pharmacological treatments, flavonoids are a family of compounds with proven neuroprotective effects and multi-targeting behavior. The American genus Dalea L. (Fabaceae) is an important source of bioactive flavonoids. In this opportunity, we tested the neuroprotective potential of three prenylated flavanones isolated from Dalea species in a new in vitro pre-clinical AD model previously developed by us. Our approach consisted in exposing neural cells to conditioned media (3xTg-AD ACM) from neurotoxic astrocytes derived from hippocampi and cortices of old 3xTg-AD mice, mimicking a local neurodegenerative microenvironment. Flavanone 1 and 3 showed a neuroprotective effect against 3xTg-AD ACM, being 1 more active than 3. The structural requirements to afford neuroprotective activity in this model are a 5'-dimethylallyl and 4'-hydroxy at the B ring. In order to search the mechanistic performance of the most active flavanone, we focus on the flavonoid-mediated regulation of GSK-3β-mediated tau phosphorylation previously reported. Flavanone 1 treatment decreased the rise of hyperphosphorylated tau protein neuronal levels induced after 3xTg-AD ACM exposure and inhibited the activity of GSK-3β. Finally, direct exposure of these neurotoxic 3xTg-AD astrocytes to flavanone 1 resulted in toxicity to these cells and reduced the neurotoxicity of 3xTg-AD ACM as well. Our results allow us to present compound 1 as a natural prenylated flavanone that could be used as a precursor to development and design of future drug therapies for AD.

Effect of Natural Osmolytes on Recombinant Tau Monomer: Propensity of Oligomerization and Aggregation

The pathological misfolding and aggregation of the microtubule associated protein tau (MAPT), a full length Tau2N4R with 441aa, is considered the principal disease relevant constituent in tauopathies including Alzheimer's disease (AD) with an imbalanced ratio in 3R/4R isoforms. The exact cellular fluid composition, properties, and changes that coincide with tau misfolding, seed formation, and propagation events remain obscure. The proteostasis network, along with the associated osmolytes, is responsible for maintaining the presence of tau in its native structure or dealing with misfolding. In this study, for the first time, the roles of natural brain osmolytes are being investigated for their potential effects on regulating the conformational stability of the tau monomer (tauM) and its propensity to aggregate or disaggregate. Herein, the effects of physiological osmolytes myo-inositol, taurine, trimethyl amine oxide (TMAO), betaine, sorbitol, glycerophosphocholine (GPC), and citrulline on tau's aggregation state were investigated. The overall results indicate the ability of sorbitol and GPC to maintain the monomeric form and prevent aggregation of tau, whereas myo-inositol, taurine, TMAO, betaine, and citrulline promote tau aggregation to different degrees, as revealed by protein morphology in atomic force microscopy images. Biochemical and biophysical methods also revealed that tau proteins adopt different conformations under the influence of these osmolytes. TauM in the presence of all osmolytes expressed no toxicity when tested by a lactate dehydrogenase assay. Investigating the conformational stability of tau in the presence of osmolytes may provide a better understanding of the complex nature of tau aggregation in AD and the protective and/or chaotropic nature of osmolytes.

Lung endothelium, tau, and amyloids in health and disease

Lung endothelia in the arteries, capillaries, and veins are heterogeneous in structure and function. Lung capillaries in particular represent a unique vascular niche, with a thin yet highly restrictive alveolar-capillary barrier that optimizes gas exchange. Capillary endothelium surveys the blood while simultaneously interpreting cues initiated within the alveolus and communicated via immediately adjacent type I and type II epithelial cells, fibroblasts, and pericytes. This cell-cell communication is necessary to coordinate the immune response to lower respiratory tract infection. Recent discoveries identify an important role for the microtubule-associated protein tau that is expressed in lung capillary endothelia in the host-pathogen interaction. This endothelial tau stabilizes microtubules necessary for barrier integrity, yet infection drives production of cytotoxic tau variants that are released into the airways and circulation, where they contribute to end-organ dysfunction. Similarly, beta-amyloid is produced during infection. Beta-amyloid has antimicrobial activity, but during infection it can acquire cytotoxic activity that is deleterious to the host. The production and function of these cytotoxic tau and amyloid variants are the subject of this review. Lung-derived cytotoxic tau and amyloid variants are a recently discovered mechanism of end-organ dysfunction, including neurocognitive dysfunction, during and in the aftermath of infection.

Circulating Biomarkers for Alzheimer's Disease: Unlocking the Diagnostic Potential in Low- and Middle-Income Countries, Focusing on Africa

BACKGROUND

Alzheimer's disease (AD) is emerging as a significant public health challenge in Africa, with predictions indicating a tripling in incidence by 2050. The diagnosis of AD on the African continent is notably difficult, leading to late detection that severely limits treatment options and significantly impacts the quality of life for patients and their families.

SUMMARY

This review focuses on the potential of high-sensitivity specific blood biomarkers as promising tools for improving AD diagnosis and management globally, particularly in Africa. These advances are particularly pertinent in the continent, where access to medical and technical resources is often limited.

KEY MESSAGES

Identifying precise, sensitive, and specific blood biomarkers could contribute to the biological characterization and management of AD in Africa. Such advances promise to improve patient care and pave the way for new regional opportunities in pharmaceutical research and drug trials on the continent for AD.

Poxvirus A51R proteins regulate microtubule stability and antagonize a cell-intrinsic antiviral response

Numerous viruses alter host microtubule (MT) networks during infection, but how and why they induce these changes is unclear in many cases. We show that the vaccinia virus (VV)-encoded A51R protein is a MT-associated protein (MAP) that directly binds MTs and stabilizes them by both promoting their growth and preventing their depolymerization. Furthermore, we demonstrate that A51R-MT interactions are conserved across A51R proteins from multiple poxvirus genera, and highly conserved, positively charged residues in A51R proteins mediate these interactions. Strikingly, we find that viruses encoding MT interaction-deficient A51R proteins fail to suppress a reactive oxygen species (ROS)-dependent antiviral response in macrophages that leads to a block in virion morphogenesis. Moreover, A51R-MT interactions are required for VV virulence in mice. Collectively, our data show that poxviral MAP-MT interactions overcome a cell-intrinsic antiviral ROS response in macrophages that would otherwise block virus morphogenesis and replication in animals.

Loss of TMEM106B exacerbates Tau pathology and neurodegeneration in PS19 mice

TMEM106B, a gene encoding a lysosome membrane protein, is tightly associated with brain aging, hypomyelinating leukodystrophy, and multiple neurodegenerative diseases, including frontotemporal lobar degeneration with TDP-43 aggregates (FTLD-TDP). Recently, TMEM106B polymorphisms have been associated with tauopathy in chronic traumatic encephalopathy (CTE) and FTLD-TDP patients. However, how TMEM106B influences Tau pathology and its associated neurodegeneration, is unclear. Here we show that loss of TMEM106B enhances the accumulation of pathological Tau, especially in the neuronal soma in the hippocampus, resulting in severe neuronal loss in the PS19 Tau transgenic mice. Moreover, Tmem106b-/- PS19 mice develop significantly increased abnormalities in the neuronal cytoskeleton, autophagy-lysosome activities, as well as glial activation, compared with PS19 and Tmem106b-/- mice. Together, our findings demonstrate that loss of TMEM106B drastically exacerbates Tau pathology and its associated disease phenotypes, and provide new insights into the roles of TMEM106B in neurodegenerative diseases.

EB1 Increases the Dynamics of Tau Droplets and Inhibits Tau Aggregation: Implications in Tauopathies

EB1, a microtubule plus end-tracking protein (+TIP), regulates microtubule dynamics. Recent evidence indicates cross-talk between EB proteins and tau, a microtubule-associated neuronal protein that is important for the growth and stability of microtubules. We investigated the interaction between tau and EB1 and the effect of binding of EB1 on tau function and aggregation. EB1 colocalized with tau in SH-SY5Y cells and coimmunoprecipitated with tau. Further, purified EB1 impaired the ability of adult tau to induce tubulin polymerization in vitro. EB1 bound to tau with a dissociation constant of 2.5 ± 0.7 μM. EB1 reduced heparin-induced tau aggregation with a half-maximal inhibitory concentration of 4.3 ± 0.2 μM, and increased the dynamics of tau in phase-separated droplets. The fluorescence recovery rate in tau droplets increased from 0.02 ± 0.01 to 0.07 ± 0.03 s-1, while the half-time of recovery decreased from 44.5 ± 14 to 13.5 ± 6 s in the presence of 8 μM EB1, suggesting a delay in the transition of tau from the soluble to aggregated form in tau liquid-liquid phase separation. EB1 decreased the rate of aggregation and increased the critical concentration of tau aggregation. Dynamic light scattering, atomic force microscopy, dot blot assays, and SDS-PAGE analysis showed that EB1 inhibited the formation of oligomers and higher-order aggregates of tau. The data suggest a novel role for EB1 as a regulator of tau function and aggregation, and the findings indicated the role of the EB family proteins in neuronal function and neurodegeneration.

Stress granule-mediated RNA regulatory mechanism in Alzheimer's disease

Living organisms experience a range of stresses. To cope effectively with these stresses, eukaryotic cells have evolved a sophisticated mechanism involving the formation of stress granules (SGs), which play a crucial role in protecting various types of RNA species under stress, such as mRNAs and long non-coding RNAs (lncRNAs). SGs are non-membranous cytoplasmic ribonucleoprotein (RNP) granules, and the RNAs they contain are translationally stalled. Importantly, SGs have been thought to contribute to the pathophysiology of neurodegenerative diseases, including Alzheimer's disease (AD). SGs also contain multiple RNA-binding proteins (RBPs), several of which have been implicated in AD progression. SGs are transient structures that dissipate after stress relief. However, the chronic stresses associated with aging lead to the persistent formation of SGs and subsequently to solid-like pathological SGs, which could impair cellular RNA metabolism and also act as a nidus for the aberrant aggregation of AD-associated proteins. In this paper, we provide a comprehensive summary of the physical basis of SG-enriched RNAs and SG-resident RBPs. We then review the characteristics of AD-associated gene transcripts and their similarity to the SG-enriched RNAs. Furthermore, we summarize and discuss the functional implications of SGs in neuronal RNA metabolism and the aberrant aggregation of AD-associated proteins mediated by SG-resident RBPs in the context of AD pathogenesis. Geriatr Gerontol Int 2024; 24: 7-14.

Subcellular functions of tau mediates repair response and synaptic homeostasis in injury

Injury responses in terminally differentiated cells such as neurons is tightly regulated by pathways aiding homeostatic maintenance. Cancer patients subjected to neuronal injury in brain radiation experience cognitive declines similar to those seen in primary neurodegenerative diseases. Numerous studies have investigated the effect of radiation in proliferating cells of the brain, yet the impact in differentiated, post-mitotic neurons, especially the structural and functional alterations remain largely elusive. We identified that microtubule-associated tau is a critical player in neuronal injury response via compartmentalized functions in both repair-centric and synaptic regulatory pathways. Ionizing radiation-induced injury acutely induces increase in phosphorylated tau in the nucleus and directly interacts with histone 2AX (H2AX), a DNA damage repair (DDR) marker. Loss of tau significantly reduced H2AX after irradiation, indicating that tau may play an important role in neuronal DDR response. We also observed that loss of tau increases eukaryotic elongation factor levels after irradiation, the latter being a positive regulator of protein translation. This cascades into a significant increase in synaptic proteins, resulting in disrupted homeostasis. Consequently, novel object recognition test showed decrease in learning and memory in tau-knockout mice after irradiation, and electroencephalographic activity showed increase in delta and theta band oscillations, often seen in dementia patients. Our findings demonstrate tau's previously undefined, multifunctional role in acute responses to injury, ranging from DDR response in the nucleus to synaptic function within a neuron. Such knowledge is vital to develop therapeutic strategies targeting neuronal injury in cognitive decline for at risk and vulnerable populations.

Targeted brain-specific tauopathy compromises peripheral skeletal muscle integrity and function

Tauopathies are neurodegenerative disorders in which the pathological intracellular aggregation of the protein tau causes cognitive deficits. Additionally, clinical studies report muscle weakness in populations with tauopathy. However, whether neuronal pathological tau species confer muscle weakness, and whether skeletal muscle maintains contractile capacity in primary tauopathy remains unknown. Here, we identified skeletal muscle abnormalities in a mouse model of primary tauopathy, expressing human mutant P301L-tau using adeno-associated virus serotype 8 (AAV8). AAV8-P301L mice showed grip strength deficits, hyperactivity, and abnormal histological features of skeletal muscle. Additionally, spatially resolved gene expression of muscle cross sections were altered in AAV8-P301L myofibers. Transcriptional changes showed alterations of genes encoding sarcomeric proteins, proposing a weakness phenotype. Strikingly, specific force of the soleus muscle was blunted in AAV8-P301L tau male mice. Our findings suggest tauopathy has peripheral consequences in skeletal muscle that contribute to weakness in tauopathy.

Atomic Force Microscopy Applied to the Study of Tauopathies

Atomic force microscopy (AFM) is a scanning probe microscopy technique which has a physical principle, the measurement of interatomic forces between a very thin tip and the surface of a sample, allowing the obtaining of quantitative data at the nanoscale, contributing to the surface study and mechanical characterization. Due to its great versatility, AFM has been used to investigate the structural and nanomechanical properties of several inorganic and biological materials, including neurons affected by tauopathies. Tauopathies are neurodegenerative diseases featured by aggregation of phosphorylated tau protein inside neurons, leading to functional loss and progressive neurotoxicity. In the broad universe of neurodegenerative diseases, tauopathies comprise the most prevalent, with Alzheimer's disease as its main representative. This review highlights the use of AFM as a suitable research technique for the study of cellular damages in tauopathies, even in early stages, allowing elucidation of pathogenic mechanisms of these diseases.

Design, Synthesis, and Characterization of Novel Styryl Dyes as Fluorescent Probes for Tau Aggregate Detection in Vitro and in Cells

A series of novel styryl dye derivatives incorporating indolium and quinolinium core structures were successfully synthesized to explore their interacting and binding capabilities with tau aggregates in vitro and in cells. The synthesized dyes exhibited enhanced fluorescence emission in viscous environments due to the rotatable bond confinement in the core structure. Dye 4, containing a quinolinium moeity and featuring two cationic sites, demonstrated a 28-fold increase in fluorescence emission upon binding to tau aggregates. This dye could also stain tau aggregates in living cells, confirmed by cell imaging using confocal fluorescence microscopy. A molecular docking study was conducted to provide additional visualization and support for binding interactions. This work offers novel and non-cytotoxic fluorescent probes with desirable photophysical properties, which could potentially be used for studying tau aggregates in living cells, prompting further development of new fluorescent probes for early Alzheimer's disease detection.

Systematic characterization of protein structural features of alternative splicing isoforms using AlphaFold 2

Alternative splicing is an important cellular process in eukaryotes, altering pre-mRNA to yield multiple protein isoforms from a single gene. However, our understanding of the impact of alternative splicing events on protein structures is currently constrained by a lack of sufficient protein structural data. To address this limitation, we employed AlphaFold 2, a cutting-edge protein structure prediction tool, to conduct a comprehensive analysis of alternative splicing for approximately 3,000 human genes, providing valuable insights into its impact on the protein structural. Our investigation employed state of the art high-performance computing infrastructure to systematically characterize structural features in alternatively spliced regions and identified changes in protein structure following alternative splicing events. Notably, we found that alternative splicing tends to alter the structure of residues primarily located in coils and beta-sheets. Our research highlighted a significant enrichment of loops and highly exposed residues within human alternatively spliced regions. Specifically, our examination of the Septin-9 protein revealed potential associations between loops and alternative splicing, providing insights into its evolutionary role. Furthermore, our analysis uncovered two missense mutations in the Tau protein that could influence alternative splicing, potentially contributing to the pathogenesis of Alzheimer's disease. In summary, our work, through a thorough statistical analysis of extensive protein structural data, sheds new light on the intricate relationship between alternative splicing, evolution, and human disease.

Retinal Alterations Predict Early Prodromal Signs of Neurodegenerative Disease

Neurodegenerative diseases are an increasingly common group of diseases that occur late in life with a significant impact on personal, family, and economic life. Among these, Alzheimer's disease (AD) and Parkinson's disease (PD) are the major disorders that lead to mild to severe cognitive and physical impairment and dementia. Interestingly, those diseases may show onset of prodromal symptoms early after middle age. Commonly, the evaluation of these neurodegenerative diseases is based on the detection of biomarkers, where functional and structural magnetic resonance imaging (MRI) have shown a central role in revealing early or prodromal phases, although it can be expensive, time-consuming, and not always available. The aforementioned diseases have a common impact on the visual system due to the pathophysiological mechanisms shared between the eye and the brain. In Parkinson's disease, α-synuclein deposition in the retinal cells, as well as in dopaminergic neurons of the substantia nigra, alters the visual cortex and retinal function, resulting in modifications to the visual field. Similarly, the visual cortex is modified by the neurofibrillary tangles and neuritic amyloid β plaques typically seen in the Alzheimer's disease brain, and this may reflect the accumulation of these biomarkers in the retina during the early stages of the disease, as seen in postmortem retinas of AD patients. In this light, the ophthalmic evaluation of retinal neurodegeneration could become a cost-effective method for the early diagnosis of those diseases, overcoming the limitations of functional and structural imaging of the deep brain. This analysis is commonly used in ophthalmic practice, and interest in it has risen in recent years. This review will discuss the relationship between Alzheimer's disease and Parkinson's disease with retinal degeneration, highlighting how retinal analysis may represent a noninvasive and straightforward method for the early diagnosis of these neurodegenerative diseases.

The ameliorative effect of Piper trioicum in attenuating cognitive deficit in scopolamine induced neurotoxicity in experimental rats

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional system of medicine, Piper species, or its components are widely used to treat many diseases including memory improvement. One of the wild species Piper trioicum Roxb. (Piperaceae) is found in South Asian countries. The whole plant is used as folk medicine to improve memory.

AIM OF THE STUDY

To our knowledge, no previous research has investigated the neuroprotective activities of P. trioicum. So, we studied the ameliorative effect of P. trioicum in attenuating cognitive deficit in scopolamine induced neurotoxicity in experimental rats.

MATERIALS AND METHODS

Wistar rats were exposed to scopolamine (3 mg/kg, i. p.) for 14 consecutive days, and the effect of P. trioicum (HAPT; oral, 300, 400 mg/kg) on scopolamine-invoked neurotoxicity in brain were studied. During the experimental period, behaviour analyses of rats were observed 30 min post-drug administration. The role of antioxidants of HAPT in scavenging cellular oxygen/peroxyl radicals were studied. Acetylcholinesterase and butyrylcholinesterase inhibitions, and mode of inhibition kinetics of HAPT were studied. Pathogenic cellular oxidative (MDA, GSH, SOD, and CAT), DNA damage (8-oxodG), neurochemical (acetyl- and, butyryl-cholinesterase), β-secretase (BACE-1 and 2), MAPτ, and neuroinflammation (IL-6, TNF-α) biomarkers in extension to the histopathological observation of brain cortex were studied. GC-MS/MS analysis was carried out to investigate the presence of bioactive constituents in HAPT.

RESULTS

HAPT, a rich source of phenol and flavonoid type antioxidants were responsible in quenching oxygen/peroxyl radicals and protected the cellular membrane, and lipoproteins against ROS in DPPH, ORAC, and CAPe tests. HAPT inhibited acetylcholinesterase and butyrylcholinesterase activities, and showed competitive-inhibition (reversible) towards cholinesterase activities. HAPT-400 significantly improved the learning and memory-impairment by restoring oxidative MDA, GSH, SOD, CAT, and DNA damage (8-oxodG) markers of serum, and cortex. It also improved acetyl- and, butyryl-cholinesterase, β-secretase, and MAPτ level in brain by restoring proinflammatory cytokines IL-6, and TNF-α indicators in neurotoxic rats. GC-MS/MS reported therapeutic significance active compounds were molecular-docked towards target proteins, found that proscillaridin showed the highest affinity towards AChE, BuChE, BACE1, and BACE2 with binding energy of ΔGb -9.1, ΔGb -10.2, ΔGb -11.4 and ΔGb -11.5 Kcal/mol, respectively. Cymarin and morphine-3-glucuronide showed the second highest binding affinity towards AChE (ΔGb -8.8) and BuChE (ΔGb -10.0), respectively. In BACE-1, betulin showed the second highest binding affinity ΔGb -10.7 Kcal/mol and in BACE-2, morphine-3-glucuronide showed the second highest binding affinity ΔGb -9.8 Kcal/mol.

CONCLUSIONS

Synergistic impact of proscillaridin, Cymarin, morphine-3-glucuronide, betulin like compounds in HAPT improved memory impairment, healing of tissue architecture of cortex with the restoration of neurochemical, neuroinflammation, and oxidative indicators in neurotoxic rats.

Neurons cytoskeletal architecture remodeling during the replication cycle of mouse coronavirus MHV-JHM: a morphological in vitro study

Nowadays, the population is still struggling with a post-COVID19 syndrome known as long COVID, including a broad spectrum of neurological problems. There is an urgent need for a better understanding and exploration of the mechanisms of coronavirus neurotropism. For this purpose, the neurotropic strain of mouse hepatitis virus (MHV-JHM) originating from the beta-coronavirus genus, the same as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been used. The role of the cytoskeleton during virus replication in neurons in vitro was determined to understand the mechanisms of MHV-JHM neuroinfection. We have described for the first time the changes of actin filaments during MHV-JHM infection. We also observed productive replication of MHV-JHM in neurons during 168 h p.i. and syncytial cytopathic effect. We discovered that the MHV-JHM strain modulated neuronal cytoskeleton during infection, which were manifested by: (i) condensation of actin filaments in the cortical layer of the cytoplasm, (ii) formation of microtubule cisternae structures containing viral antigen targeting viral replication site (iii) formation of tunneling nanotubes used by MHV-JHM for intercellular transport. Additionally, we demonstrated that the use of cytoskeletal inhibitors have reduced virus replication in neurons, especially noscapine and nocodazole, the microtubule shortening factors.

Modulation of Tau Pathology in Alzheimer's Disease by Dietary Bioactive Compounds

Tau is a microtubule-associated protein essential for microtubule assembly and stability in neurons. The abnormal intracellular accumulation of tau aggregates is a major characteristic of brains from patients with Alzheimer's disease (AD) and other tauopathies. In AD, the presence of neurofibrillary tangles (NFTs), which is composed of hyperphosphorylated tau protein, is positively correlated with the severity of the cognitive decline. Evidence suggests that the accumulation and aggregation of tau cause synaptic dysfunction and neuronal degeneration. Thus, the prevention of abnormal tau phosphorylation and elimination of tau aggregates have been proposed as therapeutic strategies for AD. However, currently tau-targeting therapies for AD and other tauopathies are limited. A number of dietary bioactive compounds have been found to modulate the posttranslational modifications of tau, including phosphorylation, small ubiquitin-like modifier (SUMO) mediated modification (SUMOylation) and acetylation, as well as inhibit tau aggregation and/or promote tau degradation. The advantages of using these dietary components over synthetic substances in AD prevention and intervention are their safety and accessibility. This review summarizes the mechanisms leading to tau pathology in AD and highlights the effects of bioactive compounds on the hyperphosphorylation, aggregation and clearance of tau protein. The potential of using these bioactive compounds for AD prevention and intervention is also discussed.

In silico anti-alzheimer study of phytochemicals from Lamiaceae family through GSK3-β inhibition

Glycogen synthase kinase 3-beta (GSK3-β) is a serine-threonine protease expressed in the brain, and its hyperactivity is considered the underlying cause of Alzheimer's disease. This enzyme requires an ATP molecule in its N-terminal lobe to phosphorylate its substrates, with the most important substrate being the Tau protein. This study focuses on the inhibitory mechanism of four naturally occurring compounds-apigenin, luteolin, rosmarinic acid, and salvianolic acid-from the Laminaceae family against GSK3-β. The orientation of the ligands within the ATP-binding pocket of GSK3-β and their binding energy were determined through molecular docking. Additionally, molecular dynamics simulations was conducted to study the conformational changes induced by the ligands in the protein structure. The results showed that apigenin and salvianolic acid achieved deeper parts of the cavity compared to luteolin and rosmarinic acid and formed stable complexes with the enzyme. In the rosmarinic acid complex, the enzyme exhibited the most exposed conformation. On the other hand, luteolin binding caused a small closure of the opening, suggesting a potentially ATP-competitive role. Our results suggest these compounds as lead candidates for the design of GSK3-β inhibitors.

Unveiling New Strategies Facilitating the Implementation of Artificial Intelligence in Neuroimaging for the Early Detection of Alzheimer's Disease

Alzheimer's disease (AD) is a chronic neurodegenerative disorder with a global impact. The past few decades have witnessed significant strides in comprehending the underlying pathophysiological mechanisms and developing diagnostic methodologies for AD, such as neuroimaging approaches. Neuroimaging techniques, including positron emission tomography and magnetic resonance imaging, have revolutionized the field by providing valuable insights into the structural and functional alterations in the brains of individuals with AD. These imaging modalities enable the detection of early biomarkers such as amyloid-β plaques and tau protein tangles, facilitating early and precise diagnosis. Furthermore, the emerging technologies encompassing blood-based biomarkers and neurochemical profiling exhibit promising results in the identification of specific molecular signatures for AD. The integration of machine learning algorithms and artificial intelligence has enhanced the predictive capacity of these diagnostic tools when analyzing complex datasets. In this review article, we will highlight not only some of the most used diagnostic imaging approaches in neurodegeneration research but focus much more on new tools like artificial intelligence, emphasizing their application in the realm of AD. These advancements hold immense potential for early detection and intervention, thereby paving the way for personalized therapeutic strategies and ultimately augmenting the quality of life for individuals affected by AD.

Tubulin Complexity in Cancer and Metastasis

Tubulin plays a fundamental role in cellular function and as the subject for microtubule-active agents in the treatment of ovarian cancer. Microtubule-binding proteins (e.g., tau, MAP1/2/4, EB1, CLIP, TOG, survivin, stathmin) and posttranslational modifications (e.g., tyrosination, deglutamylation, acetylation, glycation, phosphorylation, polyamination) further diversify tubulin functionality and may permit additional opportunities to understand microtubule behavior in disease and to develop microtubule-modifying approaches to combat ovarian cancer. Tubulin-based structures that project from suspended ovarian cancer cells known as microtentacles may contribute to metastatic potential of ovarian cancer cells and could represent an exciting novel therapeutic target.

Isolation and Detection of Pathological Tau Species in a Tauopathy Mouse Model

Tau protein in Alzheimer's disease (AD) and tauopathies becomes insoluble due to hyperphosphorylation, conformational alterations, and aggregation. To analyze insoluble tau and pathological tau species, this study employs a methodology that utilizes wild-type and transgenic tau mice (P310S Tau) tissue extraction using 1% Sarkosyl or N-Lauroylsarcosine sodium salt and the radio immunoprecipitation assay (RIPA) buffer. However, the commonly used methods to study the insoluble tau fraction using detergents like Sarkosyl and RIPA require a large amount of homogenate, which can pose challenges when dealing with small tissue samples. Additionally, the study employs immunohistochemistry to visualize and quantify the pathological tau species in the brain tissue of transgenic mice, aiming to identify and analyze pathological tau species such as hyperphosphorylated tau to further our understanding of tauopathies such as Alzheimer's disease.

Reevaluating tau reduction as a therapeutic approach for tauopathies: Insights and perspectives

Tau, one of the most abundant microtubule-associated protein in neurons plays a role in regulating microtubule dynamics in axons, as well as shaping the overall morphology of the axon. Recent studies challenge the traditional view of tau as a microtubule stabilizer and shed new light on the complexity of its role in regulating various properties of the microtubule. While reducing tau levels shows therapeutic promise for early tauopathies, efficacy wanes in later stages due to resilient toxic tau aggregates and neurofibrillary tangles. Notably, tauopathies involve factors beyond toxic tau alone, necessitating a broader therapeutic approach. Overexpression of human tau in mouse models, although useful for answering some questions, may not accurately reflect disease mechanisms in patients with tauopathies. Furthermore, the interplay between tau and MAP6, another microtubule-associated protein, adds complexity to tau's regulation of microtubule dynamics. Tau promotes the formation and elongation of labile microtubule domains, vital for cellular processes, while MAP6 stabilizes microtubules. A delicate balance between these proteins is important for neuronal function. Therefore, tau reduction therapies require a comprehensive understanding of disease progression, considering functional tau loss, toxic aggregates, and microtubule dynamics. Stage-dependent application and potential unintended consequences must be carefully evaluated. Restoring microtubule dynamics in late-stage tauopathies may necessitate alternative strategies. This knowledge is valuable for developing effective and safe treatments for tauopathies.

Zebrafish Experimental Animal Models for AD: A Comprehensive Review

AD disease (AD) is a multifaceted and intricate neurodegenerative disorder characterized by intracellular neurofibrillary tangle (NFT) formation and the excessive production and deposition of Aβ senile plaques. While transgenic AD models have been found instrumental in unravelling AD pathogenesis, they involve cost and time constraints during the preclinical phase. Zebrafish, owing to their simplicity, well-defined behavioural patterns, and relevance to neurodegenerative research, have emerged as a promising complementary model. Zebrafish possess glutaminergic and cholinergic pathways implicated in learning and memory, actively contributing to our understanding of neural transmission processes. This review sheds light on the molecular mechanisms by which various neurotoxic agents, including okadaic acid (OKA), cigarette smoke extract, metals, and transgenic zebrafish models with genetic similarities to AD patients, induce cognitive impairments and neuronal degeneration in mammalian systems. These insights may facilitate the identification of effective neurotoxic agents for replicating AD pathogenesis in the zebrafish brain. In this comprehensive review, the pivotal role of zebrafish models in advancing our comprehension of AD is emphasized. These models hold immense potential for shaping future research directions and clinical interventions, ultimately contributing to the development of novel AD therapies.

Cultivation, Differentiation, and Lentiviral Transduction of Human-Induced Pluripotent Stem Cell (hiPSC)-Derived Glutamatergic Neurons for Studying Human Tau

Tau pathology is a major hallmark of many neurodegenerative diseases summarized under the term tauopathies. In most of these disorders,  such as Alzheimer's disease, the neuronal axonal microtubule-binding Tau protein becomes mislocalized to the somatodendritic compartment. In human disease, this missorting of Tau is accompanied by an abnormally high phosphorylation state of the Tau protein, and several downstream pathological consequences (e.g., loss of microtubules, degradation of postsynaptic spines, impaired synaptic transmission, neuronal death). While some mechanisms of Tau sorting, missorting, and associated pathologies have been addressed in rodent models, few studies have addressed human Tau in physiological disease-relevant human neurons. Thus, suitable human-derived in vitro models are necessary. This protocol provides a simple step-by-step protocol for generating homogeneous cultures of cortical glutamatergic neurons using an engineered Ngn2 transgene-carrying WTC11 iPSC line. We further demonstrate strategies to improve neuronal maturity, that is, synapse formation, Tau isoform expression, and neuronal activity by co-culturing hiPSC-derived glutamatergic neurons with mouse-derived astrocytes. Finally, we describe a simple protocol for high-efficiency lentiviral transduction of hiPSC-derived neurons at almost all stages of differentiation.

Recent advancements in targeted protein knockdown technologies-emerging paradigms for targeted therapy

A generalized therapeutic strategy for various disease conditions, including cancer, is to deplete or inactivate harmful protein targets. Various forms of protein or gene silencing molecules, e.g., small molecule inhibitors, RNA interference (RNAi), and microRNAs (miRNAs) have been used against druggable targets. Over the past few years, targeted protein degradation (TPD) approaches have been developed for direct degradation of candidate proteins. Among the TPD approaches, proteolysis targeting chimeras (PROTACs) have emerged as one of the most promising approaches for the selective elimination of proteins via the ubiquitin-proteasome system. Other than PROTACs, TPD methods with potential therapeutic use include intrabody-mediated protein knockdown and tripartite motif-21 (TRIM-21) mediated TRIM-Away. In this review, protein knockdown approaches, their modes of action, and their advantages over conventional gene knockdown approaches are summarized. In cancers, disease-associated protein functions are often executed by specific post-translational modifications (PTMs). The role of TRIM-Away is highlighted in the direct knockdown of PTM forms of target proteins. Moreover, the application challenges and the prospective clinical use of TPD approaches in various diseases are also discussed.

Nuclear face of Tau: an inside player in neurodegeneration

Tau (Tubulin associated unit) protein is a major hallmark of Alzheimer's disease (AD) and tauopathies. Tau is predominantly an axonal protein with a crucial role in the stabilization and dynamics of the microtubules. Since the discovery of Tau protein in 1975, research efforts were concentrated on the pathophysiological role of Tau protein in the context of the microtubules. Although, for more than three decades, different localizations of Tau protein have been discovered e.g., in the nuclear compartments. Discovery of the role of Tau protein in various cellular compartments especially in the nucleus opens up a new fold of complexity in tauopathies. Data from cellular models, animal models, and the human brain indicate that nuclear Tau is crucial for genome stability and to cope with cellular distress. Moreover, it's nature of nuclear translocation, its interactions with the nuclear DNA/RNA and proteins suggest it could play multiple roles in the nucleus. To comprehend Tau pathophysiology and efficient Tau-based therapies, there is an urgent need to understand whole repertoire of Tau species (nuclear and cytoplasmic) and their functional relevance. To complete the map of Tau repertoire, understanding of various species of Tau in the nucleus and cytoplasm, identification if specific transcripts of Tau, isoforms and post-translational modifications could foretell Tau's localizations and functions, and how they are modified in neurodegenerative diseases like AD, is urgently required. In this review, we explore the nuclear face of Tau protein, its nuclear localizations and functions and its linkage with Alzheimer's disease.