Alzheimer's Disease Cellular Model Research Articles

Unveiling the Role of Novel miRNA PC-5P-12969 in Alleviating Alzheimer's Disease.

The intricate and complex molecular mechanisms that underlie the progression of Alzheimer's disease (AD) have prompted a concerted and vigorous research endeavor aimed at uncovering potential avenues for therapeutic intervention. This study aims to elucidate the role of miRNA PC-5P-12969 in the pathogenesis of AD. We assessed the differential expression of miRNA PC-5P-12969 in postmortem AD brains, AD animal and cell models using real-time reverse-transcriptase RT-PCR, we also checked the gene and protein expression of GSK3α and APP. Our investigation revealed a notable upregulation of miRNA PC-5P-12969 in postmortem brains of AD patients, in transgenic mouse models of AD, and in mutant APP overexpressing-HT22 cells. Additionally, our findings indicate that overexpression of miRNA PC-5P-12969 exerts a protective effect on cell survival, while concurrently mitigating apoptotic cell death. Further-more, we established a robust and specific interaction between miRNA PC-5P-12969 and GSK3α. Our luciferase reporter assays provided confirmation of the binding between miRNA PC-5P-12969 and the 3'-UTR of the GSK3α gene. Manipulation of miRNA PC-5P-12969 levels in cellular models of AD yielded noteworthy alterations in the gene and protein expression levels of both GSK3α and APP. Remarkably, the manipulation of miRNA PC-5P-12969 levels yielded significant enhancements in mitochondrial respiration and ATP production, concurrently with a reduction in mitochondrial fragmentation, thus unveiling a potential regulatory role of miRNA PC-5P-12969 in these vital cellular processes. In summary, this study sheds light on the crucial role of miRNA PC-5P-12969 and its direct interaction with GSK3α in the context of AD.

SIRT4 promotes neuronal apoptosis in models of Alzheimer's disease via the STAT2-SIRT4-mTOR pathway.

Alzheimer's disease (AD) is the leading cause of dementia and presents a considerable disease burden. Its pathology involves substantial neuronal loss, primarily attributed to neuronal apoptosis. Although sirtuin 4 (SIRT4) has been implicated in regulating apoptosis in various diseases, the role of SIRT4 in AD pathology remains unclear. The study employed APP/PS1 mice as an animal model of AD and amyloid-β (Aβ)1-42-treated HT-22 cells as an AD cell model. SIRT4 expression was determined by quantitative real-time polymerase chain reaction, western blot, and immunofluorescence. A Sirt4 knockdown model was established by intracranial injection of lentivirus-packaged sh-SIRT4 and cellular lentivirus transfection. Immunohistochemistry and flow cytometry were used to examine Aβ deposition in mice and apoptosis, respectively. Protein expression was assessed by western blot analysis. The UCSC and JASPAR databases were used to predict upstream transcription factors of SIRT4. Subsequently, the binding of transcription factors to SIRT4 was analyzed using a dual-luciferase assay and chromatin immunoprecipitation. SIRT4 expression was upregulated in both APP/PS1 mice and Aβ-treated HT-22 cells in comparison to their respective control groups. Sirt4 knockdown in animal and cellular models of AD resulted in reduced apoptosis, decreased Aβ deposition, and amelioration of learning and memory impairments in mice. Mechanistically, SIRT4 modulates apoptosis via the mTOR pathway and is negatively regulated by the transcription factor signal transducer and activator of transcription 2 (STAT2). Our study findings suggest that targeting the STAT2-SIRT4-mTOR axis may offer a new treatment approach for AD.

Icariin ameliorates glycolytic dysfunction in Alzheimer's disease models by activating the Wnt/β-catenin signaling pathway.

It was reported that the Wnt/β-catenin pathway is involved in the regulation of aerobic glycolysis and that brain glycolytic dysfunction results in the development of Alzheimer's disease (AD). Icariin (ICA), an active component extracted from Epimedii Folium, has been reported to produce neuroprotective effects in multiple models of AD, but its underlying mechanism remains to be fully described. We aimed to investigate the protective effects of ICA on animal and cell models of AD and confirm whether the Wnt/β-catenin pathway has functions in the neuroprotective function of ICA. The 3 × Tg-AD mice were treated with ICA. HT22 cells, the Aβ25-35 peptide and Dickkopf-1 (DKK1) agent (a specific inhibitor of the Wnt/β-catenin pathway) were used to further explore the underlying mechanism of ICA that produces anti-AD effects. Behavioral examination, western blotting assay, staining analysis, biochemical test, and lactate dehydrogenase (LDH) assays were applied. We first demonstrated that ICA significantly improved cognitive function and autonomous behavior, reduced neuronal damage, and reversed the protein levels and activities of glycolytic key enzymes, and expression of protein molecules of the canonical Wnt signaling pathway, in 3 × Tg-AD mice back to wild-type levels. Next, we further found that ICA increased cell viability and effectively improved the dysfunctional glycolysis in HT22 cells injured by Aβ25-35 . However, when canonical Wnt signaling was inhibited by DKK1, the above effects of ICA on glycolysis were abolished. In summary, ICA exerts neuroprotective effects in 3 × Tg-AD animals and AD cellular models by enhancing the function of glycolysis through activation of the Wnt/β-catenin pathway.

Translocator protein (TSPO) ligands attenuate mitophagy deficits in the SH-SY5Y cellular model of Alzheimer's disease via the autophagy adaptor P62

Mitochondrial dysfunction has been widely implicated in the pathogenesis of Alzheimer's disease (AD), with accumulation of damaged and dysfunctional mitochondria occurring early in the disease. Mitophagy, which governs mitochondrial turnover and quality control, is impaired in the AD brain, and strategies aimed at enhancing mitophagy have been identified as promising therapeutic targets. The translocator protein (TSPO) is an outer mitochondrial membrane protein that is upregulated in AD, and ligands targeting TSPO have been shown to exert neuroprotective effects in mouse models of AD. However, whether TSPO ligands modulate mitophagy in AD has not been explored. Here, we provide evidence that the TSPO-specific ligands Ro5-4864 and XBD173 attenuate mitophagy deficits and mitochondrial fragmentation in a cellular model of AD overexpressing the human amyloid precursor protein (APP). Ro5-4864 and XBD173 appear to enhance mitophagy via modulation of the autophagic cargo receptor P62/SQSTM1, in the absence of an effect on PARK2, PINK1, or LC3 level. Taken together, these findings indicate that TSPO ligands may be promising therapeutic agents for ameliorating mitophagy deficits in AD.

Moschus ameliorates glutamate-induced cellular damage by regulating autophagy and apoptosis pathway

Alzheimer's disease (AD), a neurodegenerative disorder, causes short-term memory and cognition declines. It is estimated that one in three elderly people die from AD or other dementias. Chinese herbal medicine as a potential drug for treating AD has gained growing interest from many researchers. Moschus, a rare and valuable traditional Chinese animal medicine, was originally documented in Shennong Ben Cao Jing and recognized for its properties of reviving consciousness/resuscitation. Additionally, Moschus has the efficacy of “regulation of menstruation with blood activation, relief of swelling and pain” and is used for treating unconsciousness, stroke, coma, and cerebrovascular diseases. However, it is uncertain whether Moschus has any protective effect on AD patients. We explored whether Moschus could protect glutamate (Glu)-induced PC12 cells from cellular injury and preliminarily explored their related action mechanisms. The chemical compounds of Moschus were analyzed and identified by GC–MS. The Glu-induced differentiated PC12 cell model was thought to be the common AD cellular model. The study aims to preliminarily investigate the intervention effect of Moschus on Glu-induced PC12 cell damage as well as their related action mechanisms. Cell viability, lactate dehydrogenase (LDH), mitochondrial reactive oxygen species, mitochondrial membrane potential (MMP), cell apoptosis, autophagic vacuoles, autolysosomes or autophagosomes, proteins related to apoptosis, and the proteins related to autophagy were examined and analyzed. Seventeen active compounds of the Moschus sample were identified based on GC–MS analysis. In comparison to the control group, Glu stimulation increased cell viability loss, LDH release, mitochondrial damage, loss of MMP, apoptosis rate, and the number of cells containing autophagic vacuoles, and autolysosomes or autophagosomes, while these results were decreased after the pretreatment with Moschus and 3-methyladenine (3-MA). Furthermore, Glu stimulation significantly increased cleaved caspase-3, Beclin1, and LC3II protein expression, and reduced B-cell lymphoma 2/BAX ratio and p62 protein expression, but these results were reversed after pretreatment of Moschus and 3-MA. Moschus has protective activity in Glu-induced PC12 cell injury, and the potential mechanism might involve the regulation of autophagy and apoptosis. Our study may promote research on Moschus in the field of neurodegenerative diseases, and Moschus may be considered as a potential therapeutic agent for AD.

Pirh2 modulates amyloid-β aggregation through the regulation of glucose-regulated protein 78 and chaperone-mediated signaling.

Amyloid-β (Aβ) protein aggregation in the brain is a pathological hallmark of Alzheimer's disease (AD) however, the underlying molecular mechanisms regulating amyloid aggregation are not well understood. Here, we studied the propitious role of E3 ubiquitin ligase Pirh2 in Aβ protein aggregation in view of its regulatory ligase activity in the ubiquitin-proteasome systememploying both cellular and sporadic rodent models of AD. Pirh2 protein abundance was significantly increased during Streptozotocin (STZ) induced AD conditions, and transient silencing of Pirh2 significantly inhibited the Aβ aggregation and modified the dendrite morphology along with the substantial decrease in choline level in the differentiated neurons. MALDI-TOF/TOF, coimmunoprecipitation, and UbcH7-linked in vitro ubiquitylation analysis confirmed the high interaction of Pirh2 with chaperone GRP78. Furthermore, Pirh2 silencing inhibits the STZ induced altered level of endoplasmic reticulum stress and intracellular Ca2+ levels in neuronal N2a cells. Pirh2 silencing also inhibited the AD conditions related to the altered protein abundance of HSP90 and its co-chaperones which may collectively involve in the reduced burden of amyloid aggregates in neuronal cells. Pirh2 silencing further stabilized the nuclear translocation of phospho-Nrf2 and inhibited the altered level of autophagy factors. Taken together, our data indicated that Pirh2 is critically involved in STZ induced AD pathogenesis through its interaction with ER-chaperone GRP78, improves the neuronal connectivity, affects the altered level of chaperones, co-chaperones, & autophagic markers, and collectively inhibits the Aβ aggregation.

Hederagenin Upregulates PTPN1 Expression in Aβ-Stimulated Neuronal Cells, Exerting Anti-Oxidative Stress and Anti-Apoptotic Activities.

Alzheimer's disease (AD) is a prevalently neurodegenerative disease characterized by neuronal damage which is associated with amyloid-β (Aβ) accumulation. Hederagenin is a triterpenoid saponin, exerting anti-apoptotic, anti-oxidative, anti-inflammatory, anti-tumoral, and neuroprotective activities. However, its role in AD progression is still obscure. The aim of this study was to explore the influences of hederagenin on Aβ-caused neuronal injury in vitro. Neuronal cells were treated with Aβ25-35 (Aβ) to establish a cellular model of AD. Cell viability was assessed using cell counting kit-8 (CCK-8). Oxidative stress was evaluated by detecting reactive oxygen species (ROS) generation and superoxide dismutase (SOD) activity. Apoptosis was investigated using TUNEL staining and caspase-3 activity assays. Protein tyrosine phosphatase nonreceptor type 1 (PTPN1) was screened by bioinformatics analysis. Protein levels of PTPN1 and protein kinase B (Akt) were measured by western blotting. Hederagenin (2.5, 5, and 10μM) alone did not affect viability of neuronal cells, but relieved Aβ-induced viability reduction. Hederagenin mitigated Aβ-induced increase in ROS accumulation and decrease in SOD activity. Hederagenin attenuated Aβ-induced increase in apoptotic rate and caspase-3 activity. PTPN1 was screened as a target of hederagenin against AD by bioinformatics analysis. Hederagenin treatment resisted Aβ-induced decrease in PTPN1 mRNA and protein levels in neuronal cells. PTPN1 silencing attenuated the suppressive functions of hederagenin in Aβ-stimulated oxidative stress and apoptosis. Hederagenin mitigated Aβ-induced Akt signaling inactivation by upregulating PTPN1 expression. In conclusion, hederagenin attenuates oxidative stress and apoptosis in neuronal cells stimulated with Aβ by promoting PTPN1/Akt signaling activation.

Targeting lncRNA NEAT1 hampers Alzheimer's disease progression.

Long noncoding RNA nuclear enriched abundant transcript 1 (lnc-NEAT1) is closely implicated in neurological diseases, while its implication in Alzheimer's disease (AD) is rarely reported. This study aimed to investigate the effect of lnc-NEAT1 knockdown on neuron injury, inflammation, and oxidative stress in AD, as well as its interaction with downstream targets and pathways. APPswe/PS1dE9 transgenic mice were injected with negative control or lnc-NEAT1 interference lentivirus. Besides, AD cellular model was constructed by amyloid β treatment in mice primary neuron cells; then, knockdown of lnc-NEAT1 and microRNA-193a was performed alone or in combination. In vivo experiments revealed that Lnc-NEAT1 knockdown improved cognition in AD mice reflected by Morrison water maze and Y-maze assays. Besides, lnc-NEAT1 knockdown reduced injury and apoptosis, decreased inflammatory cytokine levels, repressed oxidative stress level, and activated adenosine cyclophosphate response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) and nuclear factor erythroid 2-related factor 2 (NRF2)/nicotinamide adenine dinucleotide phosphate dehydrogenase 1 (NQO1) pathways in hippocampi of AD mice. Notably, lnc-NEAT1 down-regulated microRNA-193a both in vitro and in vivo and acted as a decoy of microRNA-193a. In vitro experiments showed that lnc-NEAT1 knockdown decreased apoptosis and oxidative stress, improved cell viability, also activated CREB/BDNF and NRF2/NQO1 pathways in AD cellular model. Meanwhile, microRNA-193a knockdown showed the opposite effects, which also attenuated lnc-NEAT1 knockdown-mediated reduction in injury, oxidative stress, and CREB/BDNF and NRF2/NQO1 pathways of AD cellular model. In conclusion, lnc-NEAT1 knockdown reduces neuron injury, inflammation, and oxidative stress through activating microRNA-193a mediated CREB/BDNF and NRF2/NQO1 pathways in AD.

Roles of Non-Coding RNA in Alzheimer's Disease Pathophysiology.

Alzheimer's disease (AD) is a chronic neurodegenerative disorder that is accompanied by deficits in memory and cognitive functions. The disease is pathologically characterised by the accumulation and aggregation of an extracellular peptide referred to as amyloid-β (Aβ) in the form of amyloid plaques and the intracellular aggregation of a hyperphosphorelated protein tau in the form of neurofibrillary tangles (NFTs) that cause neuroinflammation, synaptic dysfunction, and oxidative stress. The search for pathomechanisms leading to disease onset and progression has identified many key players that include genetic, epigenetic, behavioural, and environmental factors, which lend support to the fact that this is a multi-faceted disease where failure in various systems contributes to disease onset and progression. Although the vast majority of individuals present with the sporadic (non-genetic) form of the disease, dysfunctions in numerous protein-coding and non-coding genes have been implicated in mechanisms contributing to the disease. Recent studies have provided strong evidence for the association of non-coding RNAs (ncRNAs) with AD. In this review, we highlight the current findings on changes observed in circular RNA (circRNA), microRNA (miRNA), short interfering RNA (siRNA), piwi-interacting RNA (piRNA), and long non-coding RNA (lncRNA) in AD. Variations in these ncRNAs could potentially serve as biomarkers or therapeutic targets for the diagnosis and treatment of Alzheimer's disease. We also discuss the results of studies that have targeted these ncRNAs in cellular and animal models of AD with a view for translating these findings into therapies for Alzheimer's disease.

Nanoscale reorganisation of synaptic proteins in Alzheimer's disease.

Synaptic strength depends strongly on the subsynaptic organisation of presynaptic transmitter release and postsynaptic receptor densities, and their alterations are expected to underlie pathologies. Although synaptic dysfunctions are common pathogenic traits of Alzheimer's disease (AD), it remains unknown whether synaptic protein nano-organisation is altered in AD. Here, we systematically characterised the alterations in the subsynaptic organisation in cellular and mouse models of AD. We used immunostaining and super-resolution stochastic optical reconstruction microscopy imaging to quantitatively examine the synaptic protein nano-organisation in both Aβ1-42-treated neuronal cultures and cortical sections from a mouse model of AD, APP23 mice. We found that Aβ1-42-treatment of cultured hippocampal neurons decreased the synaptic retention of postsynaptic scaffolds and receptors and disrupted their nanoscale alignment to presynaptic transmitter release sites. In cortical sections, we found that while GluA1 receptors in wild-type mice were organised in subsynaptic nanoclusters with high local densities, receptors in APP23 mice distributed more homogeneously within synapses. This reorganisation, together with the reduced overall receptor density, led to reduced glutamatergic synaptic transmission. Meanwhile, the transsynaptic alignment between presynaptic release-guiding RIM1/2 and postsynaptic scaffolding protein PSD-95 was reduced in APP23 mice. Importantly, these reorganisations were progressive with age and were more pronounced in synapses in close vicinity of Aβ plaques with dense cores. Our study revealed a spatiotemporal-specific reorganisation of synaptic nanostructures in AD and identifies dense-core amyloid plaques as the major local inductor in APP23 mice.

The long non-coding RNA BDNF-AS induces neuronal cell apoptosis by targeting miR-125b-5p in Alzheimer's disease models.

At least 55 million individuals suffer from dementia globally, of which Alzheimer's disease (AD) accounts for 60-70% of cases. Alzheimer's disease is the only major cause of death that is still growing. However, the molecular mechanisms are largely unknown in the progress of AD. The goal of the study was to assess whether lncRNA brain-derived neurotrophic factor antisense (BDNF-AS) could affect processes underlying the regulation of neuronal cell apoptosis in rat and cellular models of AD by directing the expression of miR-125b-5p. The amyloid-β (Aβ)1-42-induced rat and cellular models of AD were established. Changes in learning and memory in rats were detected with the use of the Morris water maze. Cell viability and apoptosis were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) test and flow cytometry. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was applied to detect the expression of lncRNA BDNF-AS and miR-125b-5p, and western blotting was utilized to examine proteins. The correlations between lncRNA BDNF-AS and miR-125b-5p were demonstrated using dual-luciferase reporter gene assays. Our results showed that BDNF-AS was upregulated and miR-125b-5p was downregulated in the rat and cellular AD models. The addition of si-BDNF-AS and miR-125b-5p mimics shortened the escape latency and swimming distance in the rat model. Furthermore, the knockdown of BDNF-AS or the administration of miR-125b-5p mimic significantly suppressed cell apoptosis, cell inflammatory, and inflammatory pathway-related proteins, while these cellular activities were promoted in rat and cellular models of AD. Additionally, miR-125b-5p was found to be a BDNF-AS target gene that was linked negatively with BDNF-AS in AD. Through regulation of miR-125b-5p, lncRNA BDNF-AS suppressed cell death, inflammation and inflammatory pathway-related proteins in AD models, which provides a potential biomarker and therapeutic target in the clinical treatment of AD.

Exploring Rosiglitazone's Potential to Treat Alzheimer's Disease through the Modulation of Brain-Derived Neurotrophic Factor.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that debilitates over 55 million individuals worldwide. Currently, treatments manage and alleviate its symptoms; however, there is still a need to find a therapy that prevents or halts disease progression. Since AD has been labeled as "type 3 diabetes" due to its similarity in pathological hallmarks, molecular pathways, and comorbidity with type 2 diabetes mellitus (T2DM), there is growing interest in using anti-diabetic drugs for its treatment. Rosiglitazone (RSG) is a peroxisome proliferator-activated receptor-gamma agonist that reduces hyperglycemia and hyperinsulinemia and improves insulin signaling. In cellular and rodent models of T2DM-associated cognitive decline and AD, RSG has been reported to improve cognitive impairment and reverse AD-like pathology; however, results from human clinical trials remain consistently unsuccessful. RSG has also been reported to modulate the expression of brain-derived neurotrophic factor (BDNF), a protein that regulates neuroplasticity and energy homeostasis and is implicated in both AD and T2DM. The present review investigates RSG's limitations and potential therapeutic benefits in pre-clinical models of AD through its modulation of BDNF expression.

Combination of Secondary Plant Metabolites and Micronutrients Improves Mitochondrial Function in a Cell Model of Early Alzheimer's Disease.

Alzheimer's disease (AD) is characterized by excessive formation of beta-amyloid peptides (Aβ), mitochondrial dysfunction, enhanced production of reactive oxygen species (ROS), and altered glycolysis. Since the disease is currently not curable, preventive and supportive approaches are in the focus of science. Based on studies of promising single substances, the present study used a mixture (cocktail, SC) of compounds consisting of hesperetin (HstP), magnesium-orotate (MgOr), and folic acid (Fol), as well as the combination (KCC) of caffeine (Cof), kahweol (KW) and cafestol (CF). For all compounds, we showed positive results in SH-SY5Y-APP695 cells-a model of early AD. Thus, SH-SY5Y-APP695 cells were incubated with SC and the activity of the mitochondrial respiration chain complexes were measured, as well as levels of ATP, Aβ, ROS, lactate and pyruvate. Incubation of SH-SY5Y-APP695 cells with SC significantly increased the endogenous respiration of mitochondria and ATP levels, while Aβ1-40 levels were significantly decreased. Incubation with SC showed no significant effects on oxidative stress and glycolysis. In summary, this combination of compounds with proven effects on mitochondrial parameters has the potential to improve mitochondrial dysfunction in a cellular model of AD.

MicroRNA-128 suppresses tau phosphorylation and reduces amyloid-beta accumulation by inhibiting the expression of GSK3β, APPBP2, and mTOR in Alzheimer's disease.

Alzheimer's disease (AD) is characterized by the abnormal accumulation of hyperphosphorylated tau proteins and amyloid-beta (Aβ) peptides. Recent studies have shown that many microRNAs (miRNAs) are dysregulated in AD, and modulation of these miRNAs can influence the development of tau and Aβ pathology. The brain-specific miRNA miR-128, encoded by MIR128-1 and MIR128-2, is important for brain development and dysregulated in AD. In this study, the role of miR-128 in tau and Aβ pathology as well as the regulatory mechanism underlying its dysregulation were investigated. The effect of miR-128 on tau phosphorylation and Aβ accumulation was examined in AD cellular models through miR-128 overexpression and inhibition. The therapeutic potential of miR-128 in AD mouse model was assessed by comparing phenotypes of 5XFAD mice administered with miR-128-expressing AAVs with 5XFAD mice administered with control AAVs. Phenotypes examined included behavior, plaque load, and protein expression. The regulatory factor of miR-128 transcription was identified through luciferase reporter assay and validated by siRNA knockdown and ChIP analysis. Both gain-of-function and loss-of-function studies in AD cellular models reveal that miR-128 represses tau phosphorylation and Aβ secretion. Subsequent investigations show that miR-128 directly inhibits the expression of tau phosphorylation kinase GSK3β and Aβ modulators APPBP2 and mTOR. Upregulation of miR-128 in the hippocampus of 5XFAD mice ameliorates learning and memory impairments, decreases plaque deposition, and enhances autophagic flux. We further demonstrated that C/EBPα transactivates MIR128-1 transcription, while both C/EBPα and miR-128 expression are inhibited by Aβ. Our findings suggest that miR-128 suppresses AD pathogenesis, and could be a promising therapeutic target for AD. We also find a possible mechanism underlying the dysregulation of miR-128 in AD, in which Aβ reduces miR-128 expression by inhibiting C/EBPα.

N-methyl-D-aspartic acid receptor 2A functionalized stationary phase: A reliable method for pursuing potential ligands against Alzheimer's disease from natural products.

N-methyl-D-aspartic acid (NMDA) receptors play subunit-specific role in central neuronal development. However, insights into the pharmacological modulation of NMDA receptors were mainly lack of subunit and synaptic selectivity. The purpose of the present study was to develop a novel strategy to rapidly recognize NMDA subunit 2A (NMDA-2A) ligands from natural products and provide subunit-selective drug candidates for Alzheimer's disease (AD). The recombinant NMDA-2A containing a tag of epidermal growth factor receptor (EGFR) was expressed in Escherichia coli cells and immobilized on ibrutinib-modified microspheres based on the specific reaction between EGFR and its inhibitor ibrutinib. A novel affinity stationary phase was synthesized to screen NMDA-2A ligands from Gardenia jasminoides Ellis. The immobilized receptor column exhibited excellent receptor selectivity and ligand-binding activity. Crocetin was screened by using this method. In a cellular model of AD, the protein level of NMDA-2A was significantly decreased compared with the control group, while treatment with crocetin significantly increased NMDA-2A level in a concentration-dependent manner, confirming that crocetin could bind to NMDA-2A in vitro. In the present study, we developed a reliable method for the rapid identification of NMDA-2A ligands from natural products, which may be used as a platform for new drug discovery to generate high-quality drug candidates.

MiR-29c-3p Attenuates β-Amyloid-Induced Neurotoxicity in Alzheimer’s Disease Through Regulating β-Site Amyloid Precursor Protein-Cleaving Enzyme 1

The aberrantly expressed microRNAs (miRNAs) including miR-29c-3p have been reported in the brains of Alzheimer's disease (AD) patients in recent researches. Nevertheless, the functional role and underlying molecular mechanism of miR-29c-3p in AD pathogenesis are still not well elucidated. The purpose of this study was to examine whether miR-29c-3p regulated β-Ameyloid (Aβ)-induced neurotoxicity by targeting β-site amyloid precursor protein-cleaving enzyme 1 (BACE1). The expressions of miR 29c 3p and BACE1 mRNA and protein levels in Aβ-treated PC12 cellular AD model were examined by qRT-PCR and western blot analyses. Luciferase reporter assay verified the potential target of miR 29c 3p. Cell viability, apoptosis, and caspase-3 activity in PC12 cells were detected by the MTT assay, flow cytometry, and caspase-3 activity assay, respectively. Our results indicated that miR-29c-3p downregulation and BACE1 upregulation existed in the cellular AD model of PC12 cells. Moreover, miR-29c-3p directly inhibited BACE1 expression. miR-29c-3p overexpression and BACE1 knockdown strengthened Aβ-induced cell apoptosis, and caspase-3 activity in PC12 cells, which was partially eliminated by over-expression of BACE1. Conversely, BACE1 knockdown reversed the miR-29c-3p inhibition- mediated inhibitory effect on Aβ-induced cell toxicity, apoptosis, and caspase-3 activity in PC12 cells. Considering, miR-29c-3p attenuated Aβ-induced neurotoxicity through targeting BACE1 in an cellular AD model of PC12, providing a potential therapeutic target for AD treatment.

Neuroprotective and Antioxidant Role of Oxotremorine-M, a Non-selective Muscarinic Acetylcholine Receptors Agonist, in a Cellular Model of Alzheimer Disease

Alzheimer disease (AD) is a multifactorial and age-dependent neurodegenerative disorder, whose pathogenesis, classically associated with the formation of senile plaques and neurofibrillary tangles, is also dependent on oxidative stress and neuroinflammation chronicization. Currently, the standard symptomatic therapy, based on acetylcholinesterase inhibitors, showed a limited therapeutic potential, whereas disease-modifying treatment strategies are still under extensive research. Previous studies have demonstrated that Oxotremorine-M (Oxo), a non-selective muscarinic acetylcholine receptors agonist, exerts neurotrophic functions in primary neurons, and modulates oxidative stress and neuroinflammation phenomena in rat brain. In the light of these findings, in this study, we aimed to investigate the neuroprotective effects of Oxo treatment in an in vitro model of AD, represented by differentiated SH-SY5Y neuroblastoma cells exposed to Aβ1-42 peptide. The results demonstrated that Oxo treatment enhances cell survival, increases neurite length, and counteracts DNA fragmentation induced by Aβ1-42 peptide. The same treatment was also able to block oxidative stress and mitochondria morphological/functional impairment associated with Aβ1-42 cell exposure. Overall, these results suggest that Oxo, by modulating cholinergic neurotransmission, survival, oxidative stress response, and mitochondria functionality, may represent a novel multi-target drug able to achieve a therapeutic synergy in AD.Graphical Illustration of the main pathological hallmarks and mechanisms underlying AD pathogenesis, including neurodegeneration and oxidative stress, efficiently counteracted by treatment with Oxo, which may represent a promising therapeutic molecule. Created with BioRender.com under academic license.

Rational Design of a Theranostic Agent Triggered by Endogenous Nitric Oxide in a Cellular Model of Alzheimer's Disease.

Oxidative damage caused by upregulated nitric oxide (NO) plays an important role in the pathogenesis of Alzheimer's disease (AD). Currently, stimulus-triggered theranostic agents have received much attention due to benefits on disease imaging and targeted therapeutic effects. However, the development of a theranostic agent triggered by NO for AD remains unexplored. Herein, through the mechanism analysis of the reaction between a fluorophore of 9,14-diphenyl-9,14-dihydrodibenzo[a,c]phenazine (DPAC) and NO, which we occasionally found and thereafter structure optimization of DPAC, a theranostic agent DPAC-(peg)4-memantine was fabricated. In an AD cellular model, DPAC-(peg)4-memantine exhibits NO sensing ability for AD imaging. Meanwhile, DPAC-(peg)4-memantine shows improved therapeutic by targeted drug release triggered by NO and sustained therapeutic effects owing to the synergetic antioxidative abilities via the anti-AD drug and NO scavenging. This work provides an unprecedented avenue for the studies on not only AD but also other diseases with NO upregulation.

Melatonin Attenuates Methamphetamine-Induced Alteration of Amyloid β Precursor Protein Cleaving Enzyme Expressions via Melatonin Receptor in Human Neuroblastoma Cells.

Alzheimer's disease (AD) is the most prominent neurodegenerative disease represented by the loss of memory and cognitive impairment symptoms and is one of the major health imperilments among the elderly. Amyloid (Aβ) deposit inside the neuron is one of the characteristic pathological hallmarks of this disease, leading to neuronal cell death. In the amyloidogenic processing, the amyloid precursor protein (APP) is cleaved by beta-secretase and γ-secretase to generate Aβ. Methamphetamine (METH) is a psychostimulant drug that causes neurodegeneration and detrimental cognitive deficits. The analogy between the neurotoxic and neurodegenerative profile of METH and AD pathology necessitates an exploration of the underlying molecular mechanisms. In the present study, we found that METH ineluctably affects APP processing, which might contribute to the marked production of Aβ in human neuroblastoma cells. Melatonin, an indolamine produced and released by the pineal gland as well as other extrapineal, has been protective against METH-induced neurodegenerative processes, thus rescuing neuronal cell death. However, the precise action of melatonin on METH has yet to be determined. We further propose to investigate the protective properties of melatonin on METH-induced APP-cleaving secretases. Pretreatment with melatonin significantly reversed METH-induced APP-cleaving secretases and Aβ production. In addition, pretreatment with luzindole, a melatonin receptor antagonist, significantly prevented the protective effect of melatonin, suggesting that the attenuation of the toxic effect on METH-induced APP processing by melatonin was mediated via melatonin receptor. The present results suggested that melatonin has a beneficial role in preventing Aβ generation in a cellular model of METH-induced AD.

Guanabenz mitigates the neuropathological alterations and cell death in Alzheimer's disease.

Alzheimer's disease (AD) pathology is characterized by cognitive impairment, increased acetylcholinesterase (AChE) activity, and impaired neuronal communication. Clinically, AChE inhibitors are being used to treat AD patients; however, these remain unable to prevent the disease progression. Therefore, further development of new therapeutic molecules is required having broad spectrum effects on AD-related various neurodegenerative events. Since repurposing is a quick mode to search the therapeutic molecules; henceforth, this study was conducted to evaluate the anti-Alzheimer activity of drug guanabenz which is already in use for the management of high blood pressure in clinics. The study was performed employing both cellular and rat models of AD along with donepezil as reference drug. Guanabenz treatment in both the experimental models showed significant protection against AD-specific behavioral and pathological indicators like AChE activity, tau phosphorylation, amyloid precursor protein, and memory retention. In conjunction, guanabenz also attenuated the AD-related oxidative stress, impaired mitochondrial functionality (MMP, cytochrome-c translocation, ATP level, and mitochondrial complex I activity), endoplasmic reticulum stress (GRP78, GADD153, cleaved caspase-12), neuronal apoptosis (Bcl-2, Bax, cleaved caspase-3), and DNA fragmentation. In conclusion, findings suggested the panoptic protective effect of guanabenz on disease-related multiple degenerative markers and signaling. Furthermore, clinical trial may shed light and expedite the availability of new therapeutic anti-Alzheimer's molecule for the wellbeing of AD patients.