scholarly journals Flow-cytometric microglial sorting coupled with quantitative proteomics identifies moesin as a highly-abundant microglial protein with relevance to Alzheimer’s disease

2019 ◽  
Author(s):  
Sruti Rayaprolu ◽  
Tianwen Gao ◽  
Hailian Xiao ◽  
Supriya Ramesha ◽  
Laura D. Weinstock ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cell Sorting ◽  
Ribosomal Proteins ◽  
Molecular Mechanisms ◽  
Synaptic Proteins ◽  
Wild Type ◽  
Proteomic Data ◽  
Core Set

AbstractBackgroundProteomic characterization of microglia provides the most proximate assessment of functionally relevant molecular mechanisms of neuroinflammation. However, microglial proteomics studies have been limited by low cellular yield and contamination by non-microglial proteins using existing enrichment strategies.MethodsWe coupled magnetic-activated cell sorting (MACS) and fluorescence activated cell sorting (FACS) of microglia with tandem mass tag-mass spectrometry (TMT-MS) to obtain a highly-pure microglial proteome and identified a core set of highly-abundant microglial proteins in adult mouse brain. We interrogated existing human proteomic data for Alzheimer’s disease (AD) relevance of highly-abundant microglial proteins and performed immuno-histochemical and in-vitro validation studies.ResultsQuantitative multiplexed proteomics by TMT-MS of CD11b+ MACS-enriched (N = 5 mice) and FACS-isolated (N = 5 mice), from adult wild-type mice, identified 1,791 proteins. A total of 203 proteins were highly abundant in both datasets, representing a core-set of highly abundant microglial proteins. In addition, we found 953 differentially enriched proteins comparing MACS and FACS-based approaches, indicating significant differences between both strategies. The FACS-isolated microglia proteome was enriched with cytosolic, endoplasmic reticulum, and ribosomal proteins involved in protein metabolism and immune system functions, as well as an abundance of canonical microglial proteins. Conversely, the MACS-enriched microglia proteome was enriched with mitochondrial and synaptic proteins and higher abundance of neuronal, oligodendrocytic and astrocytic proteins. From the 203 consensus microglial proteins with high abundance in both datasets, we confirmed microglial expression of moesin (Msn) in wild-type and 5xFAD mouse brains as well as in human AD brains. Msn expression is nearly exclusively found in microglia that surround Aβ plaques in 5xFAD brains. In in-vitro primary microglial studies, Msn silencing by siRNA decreased Aβ phagocytosis and increased lipopolysaccharide-induced production of the pro-inflammatory cytokine, tumor necrosis factor (TNF). In network analysis of human brain proteomic data, Msn was a hub protein of an inflammatory co-expression module positively associated with AD neuropathological features and cognitive dysfunction.ConclusionsUsing FACS coupled with TMT-MS as the method of choice for microglial proteomics, we define a core set of highly-abundant adult microglial proteins. Among these, we validate Msn as highly-abundant in plaque-associated microglia with relevance to human AD.

Targeting PPARalpha in Alzheimer's Disease

2018 ◽  
Vol 15 (4) ◽  
pp. 345-354 ◽  
Author(s):  
Barbara D'Orio ◽  
Anna Fracassi ◽  
Maria Paola Cerù ◽  
Sandra Moreno
Keyword(s):  
Oxidative Stress ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Molecular Mechanisms ◽  
Redox Homeostasis ◽  
Antioxidant Response ◽  
Peroxisome Proliferator ◽  
Prevailing Paradigm

Background: The molecular mechanisms underlying Alzheimer's disease (AD) are yet to be fully elucidated. The so-called “amyloid cascade hypothesis” has long been the prevailing paradigm for causation of disease, and is today being revisited in relation to other pathogenic pathways, such as oxidative stress, neuroinflammation and energy dysmetabolism. The peroxisome proliferator-activated receptors (PPARs) are expressed in the central nervous system (CNS) and regulate many physiological processes, such as energy metabolism, neurotransmission, redox homeostasis, autophagy and cell cycle. Among the three isotypes (α, β/δ, γ), PPARγ role is the most extensively studied, while information on α and β/δ are still scanty. However, recent in vitro and in vivo evidence point to PPARα as a promising therapeutic target in AD. Conclusion: This review provides an update on this topic, focussing on the effects of natural or synthetic agonists in modulating pathogenetic mechanisms at AD onset and during its progression. Ligandactivated PPARα inihibits amyloidogenic pathway, Tau hyperphosphorylation and neuroinflammation. Concomitantly, the receptor elicits an enzymatic antioxidant response to oxidative stress, ameliorates glucose and lipid dysmetabolism, and stimulates autophagy.

Genipin Attenuates Tau Phosphorylation and Aβ Levels in Cellular Models of Alzheimer's Disease

2021 ◽  
Author(s):  
Meiting Li ◽  
Nan Cai ◽  
Liang Gu ◽  
Lijun Yao ◽  
Decheng Bi ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Signaling Pathway ◽  
Molecular Mechanisms ◽  
Tau Phosphorylation ◽  
Brain Disorder ◽  
Cellular Models ◽  
Aβ Generation ◽  
Aβ Production

Abstract Alzheimer’s disease (AD) is a devastating brain disorder characterized by neurofibrillary tangles and amyloid plaques. Inhibiting Tau protein and amyloid-beta (Aβ) production or removing these molecules are considered potential therapeutic strategies for AD. Genipin is an aglycone and is isolated from the extract of Gardenia jasminoides Ellis fruit. In this study, the effect and molecular mechanisms of genipin on the inhibition of Tau aggregation and Aβ generation were investigated. The results showed that genipin bound to Tau and protected against heparin-induced Tau fibril formation. Moreover, genipin suppressed Tau phosphorylation probably by downregulating the expression of CDK5 and GSK-3β, and activated mTOR-dependent autophagy via the SIRT1/LKB1/AMPK signaling pathway in Tau-overexpressing cells. In addition, genipin decreased Aβ production by inhibiting BACE1 expression through the PERK/eIF2α signaling pathway in N2a/SweAPP cells. These data indicated that genipin could effectively lead to a significant reduction of phosphorylated Tau level and Aβ generation in vitro, suggesting that genipin might be developed into an effective therapeutic complement or a potential nutraceutical for preventing AD.

scholarly journals Arginase Inhibition Supports Survival and Differentiation of Neuronal Precursors in Adult Alzheimer’s Disease Mice

2020 ◽  
Vol 21 (3) ◽  
pp. 1133 ◽  
Author(s):  
Baruh Polis ◽  
Kolluru D. Srikanth ◽  
Vyacheslav Gurevich ◽  
Naamah Bloch ◽  
Hava Gil-Henn ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Transgenic Mice ◽  
Adult Neurogenesis ◽  
Progenitor Cell ◽  
Molecular Mechanisms ◽  
Neuronal Cell ◽  
Cell Number ◽  
Wild Type ◽  
Newborn Neuron

Adult neurogenesis is a complex physiological process, which plays a central role in maintaining cognitive functions, and consists of progenitor cell proliferation, newborn cell migration, and cell maturation. Adult neurogenesis is susceptible to alterations under various physiological and pathological conditions. A substantial decay of neurogenesis has been documented in Alzheimer’s disease (AD) patients and animal AD models; however, several treatment strategies can halt any further decline and even induce neurogenesis. Our previous results indicated a potential effect of arginase inhibition, with norvaline, on various aspects of neurogenesis in triple-transgenic mice. To better evaluate this effect, we chronically administered an arginase inhibitor, norvaline, to triple-transgenic and wild-type mice, and applied an advanced immunohistochemistry approach with several biomarkers and bright-field microscopy. Remarkably, we evidenced a significant reduction in the density of neuronal progenitors, which demonstrate a different phenotype in the hippocampi of triple-transgenic mice as compared to wild-type animals. However, norvaline showed no significant effect upon the progenitor cell number and constitution. We demonstrated that norvaline treatment leads to an escalation of the polysialylated neuronal cell adhesion molecule immunopositivity, which suggests an improvement in the newborn neuron survival rate. Additionally, we identified a significant increase in the hippocampal microtubule-associated protein 2 stain intensity. We also explore the molecular mechanisms underlying the effects of norvaline on adult mice neurogenesis and provide insights into their machinery.

scholarly journals Influence of Woodsmoke Exposure on Molecular Mechanisms Underlying Alzheimer’s Disease: Existing Literature and Gaps in Our Understanding

2020 ◽  
Vol 13 ◽  
pp. 251686572095487
Author(s):  
Adam Schuller ◽  
Luke Montrose
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Air Pollution ◽  
Molecular Mechanisms ◽  
Neurodegenerative Disorder ◽  
Ambient Air ◽  
The United States ◽  
Ambient Air Pollution ◽  
Current Status

Woodsmoke poses a significant health risk as a growing component of ambient air pollution in the United States. While there is a long history of association between woodsmoke exposure and diseases of the respiratory, circulatory, and cardiovascular systems, recent evidence has linked woodsmoke exposure to cognitive dysfunction, including Alzheimer’s disease dementia. Alzheimer’s disease is a progressive neurodegenerative disorder with largely idiopathic origins and no known cure. Here, we explore the growing body of literature which relates woodsmoke-generated and ambient air pollution particulate matter exposure to Alzheimer’s disease (AD) onset or exacerbation, in the context of an inflammation-centric view of AD. Epigenetic modifications, specifically changes in DNA methylation patterns, are well documented following woodsmoke exposure and have been shown to influence disease-favoring inflammatory cascades, induce oxidative stress, and modulate the immune response in vitro, in vivo, and in humans following exposure to air pollution. Though the current status of the literature does not allow us to draw definitive conclusions linking these events, this review highlights the need for additional work to fill gaps in our understanding of the directionality, causality, and susceptibility throughout the life course.

scholarly journals Neurotrophin-3 Promotes the Neuronal Differentiation of BMSCs and Improves Cognitive Function in a Rat Model of Alzheimer's Disease

2021 ◽  
Vol 15 ◽  
Author(s):  
Zhongrui Yan ◽  
Xianjing Shi ◽  
Hui Wang ◽  
Cuiping Si ◽  
Qian Liu ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Function ◽  
Neuronal Differentiation ◽  
Molecular Mechanisms ◽  
Therapeutic Effects ◽  
Model Of Alzheimer’S Disease ◽  
Neurotrophin 3

Transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) has the potential to be developed into an effective treatment for neurodegenerative diseases such as Alzheimer's disease (AD). However, the therapeutic effects of BMSCs are limited by their low neural differentiation rate. We transfected BMSCs with neurotrophin-3 (NT-3), a neurotrophic factor that promotes neuronal differentiation, and investigated the effects of NT-3 gene overexpression on the differentiation of BMSCs into neurons in vitro and in vivo. We further studied the possible molecular mechanisms. We found that overexpression of NT-3 promoted the differentiation of BMSCs into neurons in vitro and in vivo and improved cognitive function in rats with experimental AD. By contrast, silencing NT-3 inhibited the differentiation of BMSCs and decreased cognitive function in rats with AD. The Wnt/β-catenin signaling pathway was involved in the mechanism by which NT-3 gene modification influenced the neuronal differentiation of BMSCs in vitro and in vivo. Our findings support the prospect of using NT-3-transduced BMSCs for the development of novel therapies for AD.

scholarly journals In vitro studies of amyloid β-protein fibril assembly and toxicity provide clues to the aetiology of Flemish variant (Ala692→Gly) Alzheimer's disease

2001 ◽  
Vol 355 (3) ◽  
pp. 869-877 ◽  
Author(s):  
Dominic M. WALSH ◽  
Dean M. HARTLEY ◽  
Margaret M. CONDRON ◽  
Dennis J. SELKOE ◽  
David B. TEPLOW
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amino Acid ◽  
Amino Acid Substitution ◽  
Amyloid Β ◽  
In Vitro Studies ◽  
Amyloid Β Protein ◽  
Wild Type ◽  
Β Protein

In a Flemish kindred, an Ala692 → Gly amino acid substitution in the amyloid β-protein precursor (AβPP) causes a form of early-onset Alzheimer's disease (AD) which displays prominent amyloid angiopathy and unusually large senile plaque cores. The mechanistic basis of this Flemish form of AD is unknown. Previous in vitro studies of amyloid β-protein (Aβ) production in HEK-293 cells transfected with cDNA encoding Flemish AβPP have shown that full-length [Aβ(1–40)] and truncated [Aβ(5–40) and Aβ(11–40)] forms of Aβ are produced. In an effort to determine how these peptides might contribute to the pathogenesis of the Flemish disease, comparative biophysical and neurotoxicity studies were performed on wild-type and Flemish Aβ(1–40), Aβ(5–40) and Aβ(11–40). The results revealed that the Flemish amino acid substitution increased the solubility of each form of peptide, decreased the rate of formation of thioflavin-T-positive assemblies, and increased the SDS-stability of peptide oligomers. Although the kinetics of peptide assembly were altered by the Ala21 → Gly substitution, all three Flemish variants formed fibrils, as did the wild-type peptides. Importantly, toxicity studies using cultured primary rat cortical cells showed that the Flemish assemblies were as potent a neurotoxin as were the wild-type assemblies. Our results are consistent with a pathogenetic process in which conformational changes in Aβ induced by the Ala21 → Gly substitution would facilitate peptide adherence to the vascular endothelium, creating nidi for amyloid growth. Increased peptide solubility and assembly stability would favour formation of larger deposits and inhibit their elimination. In addition, increased concentrations of neurotoxic assemblies would accelerate neuronal injury and death.

scholarly journals Trichostatin A ameliorates Alzheimer’s disease-related pathology and cognitive deficits by increasing albumin expression and Aβ clearance in APP/PS1 mice

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Qiang Su ◽  
Tian Li ◽  
Pei-Feng He ◽  
Xue-Chun Lu ◽  
Qi Yu ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Western Blotting ◽  
Molecular Mechanisms ◽  
Neurodegenerative Disorder ◽  
Trichostatin A ◽  
Amyloid Β ◽  
Aβ Oligomers ◽  
Aβ Clearance

Abstract Background Alzheimer’s disease (AD) is an intractable neurodegenerative disorder in the elderly population, currently lacking a cure. Trichostatin A (TSA), a histone deacetylase inhibitor, showed some neuroprotective roles, but its pathology-improvement effects in AD are still uncertain, and the underlying mechanisms remain to be elucidated. The present study aims to examine the anti-AD effects of TSA, particularly investigating its underlying cellular and molecular mechanisms. Methods Novel object recognition and Morris water maze tests were used to evaluate the memory-ameliorating effects of TSA in APP/PS1 transgenic mice. Immunofluorescence, Western blotting, Simoa assay, and transmission electron microscopy were utilized to examine the pathology-improvement effects of TSA. Microglial activity was assessed by Western blotting and transwell migration assay. Protein-protein interactions were analyzed by co-immunoprecipitation and LC-MS/MS. Results TSA treatment not only reduced amyloid β (Aβ) plaques and soluble Aβ oligomers in the brain, but also effectively improved learning and memory behaviors of APP/PS1 mice. In vitro study suggested that the improvement of Aβ pathology by TSA was attributed to the enhancement of Aβ clearance, mainly by the phagocytosis of microglia, and the endocytosis and transport of microvascular endothelial cells. Notably, a meaningful discovery in the study was that TSA dramatically upregulated the expression level of albumin in cell culture, by which TSA inhibited Aβ aggregation and promoted the phagocytosis of Aβ oligomers. Conclusions These findings provide a new insight into the pathogenesis of AD and suggest TSA as a novel promising candidate for the AD treatment.

scholarly journals Reactive astrocytes augment hippocampal inhibitory tone via GABA transporter-3/4 to facilitate synaptic balance in Alzheimer’s disease

2021 ◽  
Author(s):  
Yousif Aldabbagh ◽  
Anam Islam ◽  
Weicong Zhang ◽  
Paul Whiting ◽  
Afia Ali
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Tonic Inhibition ◽  
Reactive Astrocytes ◽  
Post Mortem ◽  
Wild Type ◽  
Gaba Transporter ◽  
Synaptic Excitation ◽  
Post Mortem Brain

Background and Purpose: Cognitive decline is a major symptom in Alzheimer’s disease (AD), which is closely associated with synaptic excitatory-inhibitory imbalance. Here, we investigated whether astrocytic mechanisms involving the astrocyte-specific GABA transporter 3/4 (GAT3/4) play a role in altering the synaptic balance in AD and whether these mechanisms correlate with presynaptic cannabinoid type-1 receptors (CB1-Rs). Experimental approach: Using the APPNL-F/NL-F knock-in mouse model of AD, aged-matched to wild-type mice, we performed in vitro electrophysiological whole-cell recordings combined with immunohistochemistry in the CA1 and dentate gyrus (DG) regions of the hippocampus. Comparative neuroanatomy experiments were also performed in post-mortem brain tissue from human AD patients, age-matched to healthy controls. Results: We observed a higher expression of GABA content and GAT3/4 co-localised with reactive astrocytes, which enhanced tonic inhibition in the CA1, and DG of APPNL-F/NL-F mice compared to the age-matched wild-type animals. Blocking GAT3/4 - associated tonic inhibition in APPNL-F/NL-F mice resulted in an enhanced frequency of synaptic excitation, suggesting a presynaptic mechanism. These data also correlated with an up-regulation of CB1-Rs in astrocytes and cholecystokinin (CCK)-containing interneurons, which also enhanced tonic inhibition in the AD model, but did not affect GAT3/4 -associated tonic inhibition. The neuroanatomical results were mirrored in post-mortem tissue of AD patients. Conclusions: Our data suggest that reactive astrocytes lead to augmented tonic inhibition in the hippocampus, which probably plays an important presynaptic compensatory role in attempting to restore AD-associated neuronal hyperactivity. Therefore, reducing tonic inhibition through GAT3/4 may not be a good therapeutic strategy for AD.

scholarly journals Resveratrol and Neuroprotection: Impact and Its Therapeutic Potential in Alzheimer's Disease

2020 ◽  
Vol 11 ◽  
Author(s):  
Md. Habibur Rahman ◽  
Rokeya Akter ◽  
Tanima Bhattacharya ◽  
Mohamed M. Abdel-Daim ◽  
Saad Alkahtani ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Molecular Mechanisms ◽  
Therapeutic Potential ◽  
Neuroprotective Effect ◽  
Tau Proteins ◽  
Amyloid Peptides ◽  
Work Done

Alzheimer’s disease (AD) is a progressive cortex and hippocampal neurodegenerative disease which ultimately causes cognitively impaired decline in patients. The AD pathogen is a very complex process, including aggregation of Aβ (β-amyloid peptides), phosphorylation of tau-proteins, and chronic inflammation. Exactly, resveratrol, a polyphenol present in red wine, and many plants are indicated to show the neuroprotective effect on mechanisms mostly above. Resveratrol plays an important role in promotion of non-amyloidogenic cleavage of the amyloid precursor protein. It also enhances the clearance of amyloid beta-peptides and reduces the damage of neurons. Most experimental research on AD and resveratrol has been performed in many species, both in vitro and in vivo, during the last few years. Nevertheless, resveratrol’s effects are restricted by its bioavailability in the reservoir. Therefore, scientists have tried to improve its efficiency by using different methods. This review focuses on recent work done on the cell and animal cultures and also focuses on the neuroprotective molecular mechanisms of resveratrol. It also discusses about the therapeutic potential onto the treatment of AD.

scholarly journals The Anti-Amyloidogenic Action of Doxycycline: A Molecular Dynamics Study on the Interaction with Aβ42

2019 ◽  
Vol 20 (18) ◽  
pp. 4641 ◽  
Author(s):  
Alfonso Gautieri ◽  
Marten Beeg ◽  
Marco Gobbi ◽  
Federica Rigoldi ◽  
Laura Colombo ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Molecular Dynamics ◽  
Molecular Mechanisms ◽  
Amyloid Fibrils ◽  
Neurological Diseases ◽  
Fibrillar Structure ◽  
Structure Based Drug Design

The pathological aggregation of amyloidogenic proteins is a hallmark of many neurological diseases, including Alzheimer’s disease and prion diseases. We have shown both in vitro and in vivo that doxycycline can inhibit the aggregation of Aβ42 amyloid fibrils and disassemble mature amyloid fibrils. However, the molecular mechanisms of the drug’s anti-amyloidogenic property are not understood. In this study, a series of molecular dynamics simulations were performed to explain the molecular mechanism of the destabilization of Aβ42 fibrils by doxycycline and to compare the action of doxycycline with those of iododoxorubicin (a toxic structural homolog of tetracyclines), curcumin (known to have anti-amyloidogenic activity) and gentamicin (an antibiotic with no experimental evidence of anti-amyloidogenic properties). We found that doxycycline tightly binds the exposed hydrophobic amino acids of the Aβ42 amyloid fibrils, partly leading to destabilization of the fibrillar structure. Clarifying the molecular determinants of doxycycline binding to Aβ42 may help devise further strategies for structure-based drug design for Alzheimer’s disease.

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