scholarly journals G-protein coupled receptor, PI3K and Rho signaling pathways regulate the cascades of Tau and amyloid-β in Alzheimer’s disease

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Smita Eknath Desale ◽  
Hariharakrishnan Chidambaram ◽  
Subashchandrabose Chinnathambi
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Signaling Pathways ◽  
Signaling Pathway ◽  
G Protein ◽  
Tau Protein ◽  
Amyloid Β ◽  
Small Gtpases ◽  
Gpcr Signaling ◽  
G Protein Coupled

AbstractAlzheimer’s disease is a progressive neurodegenerative disease characterized by the presence of amyloid-β plaques in the extracellular environment and aggregates of Tau protein that forms neurofibrillary tangles (NFTs) in neuronal cells. Along with these pathological proteins, the disease shows neuroinflammation, neuronal death, impairment in the immune function of microglia and synaptic loss, which are mediated by several important signaling pathways. The PI3K/Akt-mediated survival-signaling pathway is activated by many receptors such as G-protein coupled receptors (GPCRs), triggering receptor expressed on myeloid cells 2 (TREM2), and lysophosphatidic acid (LPA) receptor. The signaling pathway not only increases the survival of neurons but also regulates inflammation, phagocytosis, cellular protection, Tau phosphorylation and Aβ secretion as well. In this review, we focused on receptors, which activate PI3K/Akt pathway and its potential to treat Alzheimer’s disease. Among several membrane receptors, GPCRs are the major drug targets for therapy, and GPCR signaling pathways are altered during Alzheimer’s disease. Several GPCRs are involved in the pathogenic progression, phosphorylation of Tau protein by activation of various cellular kinases and are involved in the amyloidogenic pathway of amyloid-β synthesis. Apart from various GPCR signaling pathways, GPCR regulating/ interacting proteins are involved in the pathogenesis of Alzheimer’s disease. These include several small GTPases, Ras homolog enriched in brain, GPCR associated sorting proteins, β-arrestins, etc., that play a critical role in disease progression and has been elaborated in this review.

scholarly journals Phosphoinositides signaling modulates microglial actin remodeling and phagocytosis in Alzheimer’s disease

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Smita Eknath Desale ◽  
Subashchandrabose Chinnathambi
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurodegenerative Diseases ◽  
Signaling Pathways ◽  
Amyloid Β ◽  
Dietary Fatty Acids ◽  
Receptor Expression ◽  
Actin Binding ◽  
Actin Remodeling ◽  
Protein Deposits

AbstractAlzheimer’s disease is one of the neurodegenerative diseases, characterized by the accumulation of abnormal protein deposits, which disrupts signal transduction in neurons and other glia cells. The pathological protein in neurodegenerative diseases, Tau and amyloid-β contribute to the disrupted microglial signaling pathways, actin cytoskeleton, and cellular receptor expression. The important secondary messenger lipids i.e., phosphatidylinositols are largely affected by protein deposits of amyloid-β in Alzheimer’s disease. Phosphatidylinositols are the product of different phosphatidylinositol kinases and the state of phosphorylation at D3, D4, and D5 positions of inositol ring. Phosphatidylinositol 3,4,5-triphosphate (PI 3, 4, 5-P3) involves in phagocytic cup formation, cell polarization, whereas Phosphatidylinositol 4,5-bisphosphate (PI 4, 5-P2)-mediates the process of phagosomes formation and further its fusion with early endosome.. The necessary activation of actin-binding proteins such as Rac, WAVE complex, and ARP2/3 complex for the actin polymerization in the process of phagocytosis, migration is regulated and maintained by PI 3, 4, 5-P3 and PI 4, 5-P2. The ratio and types of fatty acid intake can influence the intracellular secondary lipid messengers along with the cellular content of phaphatidylcholine and phosphatidylethanolamine. The Amyloid-β deposits and extracellular Tau seeds disrupt phosphatidylinositides level and actin cytoskeletal network that hamper microglial-signaling pathways in AD. We hypothesize that being a lipid species intracellular levels of phosphatidylinositol would be regulated by dietary fatty acids. Further we are interested to understand phosphoinositide-based signaling cascades in phagocytosis and actin remodeling.

A Numerical Study of Sensitivity Coefficients for a Model of Amyloid Precursor Protein and Tubulin-Associated Unit Protein Transport and Agglomeration in Neurons at the Onset of Alzheimer's Disease

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
I. A. Kuznetsov ◽  
A. V. Kuznetsov
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Precursor Protein ◽  
Tau Protein ◽  
Protein Transport ◽  
Numerical Study ◽  
Amyloid Β ◽  
Precursor Protein ◽  
Model Parameters ◽  
In The Beginning

Modeling of intracellular processes occurring during the development of Alzheimer's disease (AD) can be instrumental in understanding the disease and can potentially contribute to finding treatments for the disease. The model of intracellular processes in AD, which we previously developed, contains a large number of parameters. To distinguish between more important and less important parameters, we performed a local sensitivity analysis of this model around the values of parameters that give the best fit with published experimental results. We show that the influence of model parameters on the total concentrations of amyloid precursor protein (APP) and tubulin-associated unit (tau) protein in the axon is reciprocal to the influence of the same parameters on the average velocities of the same proteins during their transport in the axon. The results of our analysis also suggest that in the beginning of AD the aggregation of amyloid-β and misfolded tau protein have little effect on transport of APP and tau in the axon, which suggests that early damage in AD may be reversible.

scholarly journals Carboxy-Terminus Tau Protein Hyperphosphorylation is Associated with Extracellular Deposits of Amyloid-β Fibrillary in a Triple-Transgenic Model of Alzheimer’s Disease

2017 ◽  
Vol 05 (03) ◽  
Author(s):  
Miguel Angel Ontiveros Torres ◽  
Leonel Castellanos Aguilar ◽  
Jonathan Lennel Gutierrez Murcia ◽  
Nayeli Martinez Zuniga ◽  
Paola Flores Rodriguez ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Tau Protein ◽  
Amyloid Β ◽  
Carboxy Terminus ◽  
Transgenic Model ◽  
Model Of Alzheimer’S Disease

Alzheimer’s Disease and other Tauopathies: Exploring Efficacy of Medicinal Plant-Derived Compounds in Alleviating Tau-Mediated Neurodegeneration

2021 ◽  
Vol 14 ◽  
Author(s):  
Siva Sundara Kumar Durairajan ◽  
Karthikeyan Selvarasu ◽  
Minu Rani Bera ◽  
Kaushik Rajaram ◽  
Ashok Iyaswamy ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Medicinal Plant ◽  
Tau Protein ◽  
Amyloid Β ◽  
Corticobasal Degeneration ◽  
Phase Iii ◽  
Disease Modifying Drugs ◽  
Stabilizing Agents ◽  
Phase Iii Clinical Trials

: Alzheimer’s disease (AD), a major form of dementia, has been reported to affect more than 50 million people worldwide. It is characterized by the presence of amyloid-β (Aβ) plaques and hyperphosphorylated Tau-associated neurofibrillary tangles in the brain. Apart from AD, microtubule (MT)-associated protein Tau is also involved in other neurodegenerative diseases called tauopathies, including Pick’s disease, frontotemporal lobar degeneration, progressive supranuclear palsy, and corticobasal degeneration. The recently unsuccessful phase III clinical trials related to Aβ-targeted therapeutic drugs indicated that alternative targets, such as Tau, should be studied to discover more effective and safer drugs. Recent drug discovery approaches to reduce AD-related Tau pathologies are primarily based on blocking Tau aggregation, inhibiting Tau phosphorylation, compensating impaired Tau function with MT-stabilizing agents, and targeting the degradation pathways in neuronal cells to degrade Tau protein aggregates. Owing to several limitations of the currently-available Tau-directed drugs, further studies are required to generate further effective and safer Tau-based disease-modifying drugs. Here, we review the studies that focused on medicinal plant-derived compounds capable of modulating the Tau protein, which is significantly elevated and hyperphosphorylated in AD and other tauopathies. We mainly considered the studies that focused on Tau protein as a therapeutic target. We reviewed several pertinent papers retrieved from PubMed and ScienceDirect using relevant keywords, with a primary focus on the Tau-targeting compounds from medicinal plants. These compounds include indolines, phenolics, flavonoids, coumarins, alkaloids, and iridoids, which have been scientifically proven to be Tau-targeting candidates for the treatment of AD.

G-Protein Coupled Receptors and Tau-different Roles in Alzheimer’s Disease

Neuroscience ◽  
2020 ◽  
Vol 438 ◽  
pp. 198-214 ◽  
Author(s):  
Hariharakrishnan Chidambaram ◽  
Subashchandrabose Chinnathambi
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
G Protein Coupled

scholarly journals Annona atemoya leaf extract ameliorates cognitive impairment in amyloid-β injected Alzheimer’s disease-like mouse model

2019 ◽  
Vol 244 (18) ◽  
pp. 1665-1679 ◽  
Author(s):  
Hye-Sun Lim ◽  
Yu Jin Kim ◽  
Eunjin Sohn ◽  
Jiyeon Yoon ◽  
Bu-Yeo Kim ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neuronal Cell Death ◽  
Growth Factor Receptor ◽  
Amyloid Β ◽  
Neuronal Cell ◽  
Bioactive Compound ◽  
Aβ Aggregation ◽  
Epidermal Growth ◽  
G Protein Coupled

Annona atemoya is a hybrid of Annona squamosa and Annona cherimola that grow in several subtropical or tropical areas such as Florida in the US, Philippines, Cuba, Jamaica, Taiwan, and Jeju in South Korea. We report that the A. atemoya leaves (AAL) have inhibitory effects on the pathogenesis and regulatory mechanisms of Alzheimer’s disease (AD). Ethanol extract of AAL prevented amyloid-β (Aβ) aggregation and increased free radical scavenging activity. In addition, AAL extract exerted protective effects against neuronal cell death in HT22 hippocampal cells. Moreover, oral administration of AAL extract significantly improved memory loss in the passive avoidance task and Y-maze test, as well as downregulated the expression of neuronal markers neuronal nuclei and brain-derived neurotrophic factor in Aβ-injected AD mice. To verify the molecular mechanisms responsible for anti-AD actions of AAL, we conducted the antibody microarray analysis and found that epidermal growth factor receptor/G protein-coupled receptor kinase 2 signaling was activated in neuronal cells and AD-like mouse models. Additionally, quantitative analyses of the six standard compounds using high-performance liquid chromatography revealed that rutin is the most abundant compound of AAL. Furthermore, efficacy analyses of six standard compounds showed that rutin and isoquercitrin had significant inhibitory activity on Aβ aggregation. Taken together with biological activity and the content of compounds, rutin maybe a bioactive compound of AAL in the AD pathogenesis. Overall, our findings provide the first scientific support for the therapeutic effects of AAL in AD and AD-related disorders. Impact statement Our study was aimed to find a novel candidate drug for Alzheimer’s disease (AD) using natural products. We assessed the effects of Annona atemoya extracts on crucial events in the pathogenesis of AD. A. atemoya leaf (AAL) extract significantly inhibited amyloid-β aggregation, oxidative stress, neuronal cell death, and memory impairment through the epidermal growth factor receptor/G protein-coupled receptor kinase 2 pathway. Simultaneous analysis using HPLC determined six standard compounds of AAL extract, and rutin was identified as a bioactive compound. Of note, the anti-AD activity of AAL extract was more significant compared to other extracts from medicinal plants of which efficacy was previously reported. The potential of AAL extract as an anti-AD agent may provide insight into the new drug development for AD treatment.

scholarly journals MKP-1 reduces Aβ generation and alleviates cognitive impairments in Alzheimer’s disease models

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Yehong Du ◽  
Yexiang Du ◽  
Yun Zhang ◽  
Zhilin Huang ◽  
Min Fu ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Signaling Pathway ◽  
Amyloid Β ◽  
Gene Promoter ◽  
Long Term Potentiation ◽  
Mapk Signaling ◽  
Mapk Signaling Pathway ◽  
Negative Regulator ◽  
Mitogen Activated Protein Kinase

AbstractMitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1) is an essential negative regulator of MAPKs by dephosphorylating MAPKs at both tyrosine and threonine residues. Dysregulation of the MAPK signaling pathway has been associated with Alzheimer’s disease (AD). However, the role of MKP-1 in AD pathogenesis remains elusive. Here, we report that MKP-1 levels were decreased in the brain tissues of patients with AD and an AD mouse model. The reduction in MKP-1 gene expression appeared to be a result of transcriptional inhibition via transcription factor specificity protein 1 (Sp1) cis-acting binding elements in the MKP-1 gene promoter. Amyloid-β (Aβ)-induced Sp1 activation decreased MKP-1 expression. However, upregulation of MKP-1 inhibited the expression of both Aβ precursor protein (APP) and β-site APP-cleaving enzyme 1 by inactivating the extracellular signal-regulated kinase 1/2 (ERK)/MAPK signaling pathway. Furthermore, upregulation of MKP-1 reduced Aβ production and plaque formation and improved hippocampal long-term potentiation (LTP) and cognitive deficits in APP/PS1 transgenic mice. Our results demonstrate that MKP-1 impairment facilitates the pathogenesis of AD, whereas upregulation of MKP-1 plays a neuroprotective role to reduce Alzheimer-related phenotypes. Thus, this study suggests that MKP-1 is a novel molecule for AD treatment.

scholarly journals RGS2 expression predicts amyloid-β sensitivity, MCI and Alzheimer’s disease: genome-wide transcriptomic profiling and bioinformatics data mining

2016 ◽  
Vol 6 (10) ◽  
pp. e909-e909 ◽  
Author(s):  
A Hadar ◽  
E Milanesi ◽  
A Squassina ◽  
P Niola ◽  
C Chillotti ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Data Mining ◽  
Alzheimer's Disease ◽  
G Protein ◽  
Amyloid Β ◽  
Healthy Individuals ◽  
Transcriptomic Profiling ◽  
Expression Levels ◽  
Genome Wide ◽  
Lower Expression

Abstract Alzheimer's disease (AD) is the most frequent cause of dementia. Misfolded protein pathological hallmarks of AD are brain deposits of amyloid-β (Aβ) plaques and phosphorylated tau neurofibrillary tangles. However, doubts about the role of Aβ in AD pathology have been raised as Aβ is a common component of extracellular brain deposits found, also by in vivo imaging, in non-demented aged individuals. It has been suggested that some individuals are more prone to Aβ neurotoxicity and hence more likely to develop AD when aging brains start accumulating Aβ plaques. Here, we applied genome-wide transcriptomic profiling of lymphoblastoid cells lines (LCLs) from healthy individuals and AD patients for identifying genes that predict sensitivity to Aβ. Real-time PCR validation identified 3.78-fold lower expression of RGS2 (regulator of G-protein signaling 2; P=0.0085) in LCLs from healthy individuals exhibiting high vs low Aβ sensitivity. Furthermore, RGS2 showed 3.3-fold lower expression (P=0.0008) in AD LCLs compared with controls. Notably, RGS2 expression in AD LCLs correlated with the patients’ cognitive function. Lower RGS2 expression levels were also discovered in published expression data sets from postmortem AD brain tissues as well as in mild cognitive impairment and AD blood samples compared with controls. In conclusion, Aβ sensitivity phenotyping followed by transcriptomic profiling and published patient data mining identified reduced peripheral and brain expression levels of RGS2, a key regulator of G-protein-coupled receptor signaling and neuronal plasticity. RGS2 is suggested as a novel AD biomarker (alongside other genes) toward early AD detection and future disease modifying therapeutics.

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