The emerging role of Wnt signaling dysregulation in the understanding and modification of age-associated diseases

High-intensity interval training stimulates remyelination via the Wnt/β-catenin pathway in cuprizone-induced demyelination mouse model

OBJECTIVES

This study aims to investigate the role of high-intensity interval training (HIIT) in promoting myelin sheath recovery during the remyelination phase in cuprizone (CPZ)-induced demyelination mice and elucidate the mechanisms involving the Wnt/β-catenin pathway.

METHODS

After 5 weeks of a 0.2% CPZ diet to induce demyelination, a 4-week recovery phase with a normal diet was followed by HIIT intervention. Mice body weight was monitored. Morris water maze (MWM) gauged spatial cognition and memory, while the open field test (OFT) assessed anxiety levels. Luxol fast blue (LFB) staining measured demyelination, and immunofluorescence examined myelin basic protein (MBP) and platelet-derived growth factor receptor-alpha (PDGFR-α). Western blotting analyzed protein expression, including MBP, PDGFR-α, glycogen synthase kinase-3β (GSK3β), β-catenin, and p-β-catenin. Real-time PCR detected mRNA expression levels of CGT and CST.

RESULTS

HIIT promoted remyelination in demyelinating mice, enhancing spatial cognition, memory, and reducing anxiety. LFB staining indicated decreased demyelination in HIIT-treated mice. Immunofluorescence demonstrated increased MBP fluorescence intensity and PDGFR-α+ cell numbers with HIIT. Western blotting revealed HIIT reduced β-catenin levels while increasing p-β-catenin and GSK3β levels. Real-time PCR demonstrated that HIIT promoted the generation of new myelin sheaths. Additionally, the Wnt/β-catenin pathway agonist, SKL2001, decreased MBP expression but increased PDGFR-α expression.

DISCUSSION

HIIT promotes remyelination by inhibiting the Wnt/β-catenin pathway and is a promising rehabilitation training for demyelinating diseases. It provides a new theoretical basis for clinical rehabilitation and care programs.

Age- and Sex-Associated Wnt Signaling Dysregulation is Exacerbated from the Early Stages of Neuropathology in an Alzheimer's Disease Model

Emerging studies suggest that Wnt signaling is dysregulated in the brains of AD patients, suggesting that this pathway may also contribute to disease progression. However, it remains to be determined whether alterations in the Wnt pathway are the cause or consequence of this disease and which elements of Wnt signaling mainly contribute to the appearance of AD histopathological markers early in disease compared to what occurs during normal aging. The present study aimed to describe the status of several canonical Wnt pathway components and the expression of the AD marker p-tau in the hippocampi of female and male 3xTg-AD mice during disease progression compared to those during normal aging. We analyzed the levels of the canonical Wnt components Wnt7a, Dkk-1, LRP6 and GSK3β as well as the levels of p-tau and BDNF at 3, 6, 9-12 and 18 months of age. We found a gradual increase in Dkk-1 levels during aging prior to Wnt7a and LRP5/6 depletion, which was strongly exacerbated in 3xTg-AD mice even at young ages and correlated with GSK3β activation and p-tau-S202/Thr205 expression. Dkk-1 upregulation, as well as the level of p-tau, was significantly greater in females than in males. Our results suggest that Dkk-1 upregulation is involved in the expression of several features of AD at early stages, which supports the possibility of positively modulating the canonical Wnt pathway as a therapeutic tool to delay this disease at early stages.

Exploring complexities of Alzheimer's disease: New insights into molecular and cellular mechanisms of neurodegeneration and targeted therapeutic interventions

Alzheimer's disease (AD), the common form of dementia globally, is a complex condition including neurodegeneration; shares incompletely known pathogenesis. Signal transduction and biological activities, including cell metabolism, growth, and death are regulated by different signaling pathways including AKT/MAPK, Wnt, Leptin, mTOR, ubiquitin, Sirt1, and insulin. Absolute evidence linking specific molecular pathways with the genesis and/or progression of AD is still lacking. Changes in gut microbiota and blood-brain barrier also cause amyloid β aggregation in AD. The current review reports significant characteristics of various signaling pathways, their relationship with each other, and how they interact in disease genesis and/or progression. Nevertheless, due to the enormous complexity of the brain and numerous chemical linkages between these pathways, the use of signaling pathways as possible targets for drug development against AD is minimal. Currently, there is no permanent cure for AD, and there is no way to stop brain cell loss. This review also aimed to draw attention to the role of a novel group of signaling pathways, which can be collectively dubbed "anti-AD pathways", in multi-target therapy for AD, where cellular metabolic functions are severely impaired. Thus, different hypotheses have been formulated and elaborated to explain the genesis of AD, which can be further explored for drug development too.

Implementing losartan potassium-laden pegylated nanocubic vesicles as a novel nanoplatform to alleviate cisplatin-induced nephrotoxicity via blocking apoptosis and activating the wnt/β-catenin/TCF-4 pathway

AIMS

Losartan potassium-laden pegylated nanocubic vesicles (LP-NCVs-PEG) have an intriguing kidney-targeted nanoplatform for acute renal injury via blocking apoptosis and activating wnt/β-catenin pathway.

MAIN METHODS

Utilizing a thin-film hydration methodology established on 42 full factorial design to produce LP loaded nanocubic formulations (LP-NCVs) which composed mainly from L-α-phosphatidylcholine and poloxamer. The optimization process was designed to select the formulation with maximum entrapment efficiency (EE %), maximum in-vitro drug release (Q8h), and minimum vesicle size (VS). The optimum formulation was then pegylated to obtain LP-NCVs-PEG formulation that shields NCVs from the harsh ecosystem of the stomach, improves their oral drug delivery performance and targets the proximal renal tubules with no systemic toxicity. Male albino rats were injected with Cisplatin (6 mg/kg, i.p.) alone or with LP-formulations (5 mg/kg/day). Kidney injury markers, inflammatory markers, apoptotic markers. Besides renal tissue expression of Wnt, β-Catenin, GSK-3β, renal RNA gene expression of TCF-4, LEF-1 and histopathology were also analyzed to display pharmacological study.

KEY FINDINGS

The pharmacokinetics studies demonstrated that LP-NCVs-PEG boosted LP bioavailability approximately 3.61 times compared to LP oral solution. Besides LP-NCVs-PEG may have an intriguing kidney-targeted nanoplatform for acute renal injury via decreased renal toxicity markers, renal expression of LEF-1, GSK3-β, caspase, TNF-α, NF-κB and TUNEL expression. Alternatively, increased renal tissue level of Bcl-2, wnt, β-catenin and TCF-4.

SIGNIFICANCE

LP-NCVs-PEG improved LP pharmacokinetics targeting the kidney and improved injury by activating wnt/β-catenin/TCF-4 pathway, blocking apoptosis, inflammation and renal toxicity markers suggesting it might be successful nephroprotective adjuvant therapy.

Mind Gaps and Bone Snaps: Exploring the Connection Between Alzheimer's Disease and Osteoporosis

PURPOSE OF REVIEW

This comprehensive review discusses the complex relationship between Alzheimer's disease (AD) and osteoporosis, two conditions that are prevalent in the aging population and result in adverse complications on quality of life. The purpose of this review is to succinctly elucidate the many commonalities between the two conditions, including shared pathways, inflammatory and oxidative mechanisms, and hormonal deficiencies.

RECENT FINDINGS

AD and osteoporosis share many aspects of their respective disease-defining pathophysiology. These commonalities include amyloid beta deposition, the Wnt/β-catenin signaling pathway, and estrogen deficiency. The shared mechanisms and risk factors associated with AD and osteoporosis result in a large percentage of patients that develop both diseases. Previous literature has established that the progression of AD increases the risk of sustaining a fracture. Recent findings demonstrate that the reverse may also be true, suggesting that a fracture early in the life course can predispose one to developing AD due to the activation of these shared mechanisms. The discovery of these commonalities further guides the development of novel therapeutics in which both conditions are targeted. This detailed review delves into the commonalities between AD and osteoporosis to uncover the shared players that bring these two seemingly unrelated conditions together. The discussion throughout this review ultimately posits that the occurrence of fractures and the mechanism behind fracture healing can predispose one to developing AD later on in life, similar to how AD patients are at an increased risk of developing fractures. By focusing on the shared mechanisms between AD and osteoporosis, one can better understand the conditions individually and as a unit, thus informing therapeutic approaches and further research. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

ERRα and ERRγ coordinate expression of genes associated with Alzheimer's disease, inhibiting DKK1 to suppress tau phosphorylation

Alzheimer's disease (AD) is a prevalent neurodegenerative disease characterized by cognitive decline and learning/memory impairment associated with neuronal cell loss. Estrogen-related receptor α (ERRα) and ERRγ, which are highly expressed in the brain, have emerged as potential AD regulators, with unelucidated underlying mechanisms. Here, we identified genome-wide binding sites for ERRα and ERRγ in human neuronal cells. They commonly target a subset of genes associated with neurodegenerative diseases, including AD. Notably, Dickkopf-1 (DKK1), a Wnt signaling pathway antagonist, was transcriptionally repressed by both ERRα and ERRγ in human neuronal cells and brain. ERRα and ERRγ repress RNA polymerase II (RNAP II) accessibility at the DKK1 promoter by modulating a specific active histone modification, histone H3 lysine acetylation (H3K9ac), with the potential contribution of their corepressor. This transcriptional repression maintains Wnt signaling activity, preventing tau phosphorylation and promoting a healthy neuronal state in the context of AD.

Differential changes in Wnt7 and Dkk1 levels in astrocytes exposed to glutamate or TNFα

Wnt signaling plays an important role in adult brain function, and its dysregulation has been implicated in the loss of neuronal homeostasis. Despite the existence of many studies on the participation of the Wnt pathway in adult neurons, its regulation in astrocytes has been scarcely explored. Several reports point to the presence of Wnt ligands in astrocytes and their possible impact on neuronal plasticity or neuronal death. We aimed to analyze the effect of the neurotransmitter glutamate and the inflammatory cytokine TNFα on the mRNA and protein levels of the canonical Wnt agonist Wnt7a and the antagonist Dkk1 in cultured astrocytes. Primary astrocyte cultures from rat cerebral cortices were exposed to glutamate or TNFα. Wnt7a and Dkk1 expression was analyzed by RT-qPCR and its protein abundance and distribution was assessed by immunofluorescence. We found high basal expression and protein levels of Wnt7a and Dkk1 in unstimulated astrocytes and overproduction of Dkk1 mRNA induced by the two stimuli. These results reveal the astrocytic source of the canonical Wnt ligands Wnt7a and Dkk1, whose levels are differentially regulated by glutamate and TNFα. Astrocytes are a significant source of Wnt ligands, the production of which can be differentially regulated under excitatory or proinflammatory conditions, thereby impacting neuronal function.

An exploration of causal relationships between nine neurological diseases and the risk of breast cancer: a Mendelian randomization study

BACKGROUND

Some preceding researches have observed that certain neurological disorders, such as Alzheimer's disease and multiple sclerosis, may affect breast cancer risk. However, whether there are causal relationships between these neurological conditions and breast cancer is inconclusive. This study was designed to explore whether neurological disorders affected the risks of breast cancer overall and of the two subtypes (ER+ and ER-).

METHODS

In the course of this study, genome-wide association study (GWAS) data for nine neurological diseases (Alzheimer's disease, multiple sclerosis, Parkinson's disease, myasthenia gravis, generalized epilepsy, intracerebral haemorrhage, cerebral atherosclerosis, brain glioblastoma, and benign meningeal tumour) were collected from the Complex Trait Genetics lab and the MRC Integrative Epidemiology Unit, and single-nucleotide polymorphisms (SNPs) extensively associated with these neurological ailments had been recognized as instrumental variables (IVs). GWAS data on breast cancer were collected from the Breast Cancer Association Consortium (BCAC). Two-sample Mendelian randomization (MR) analyses as well as multivariable MR analyses were performed to determine whether these SNPs contributed to breast cancer risk. Additionally, the accuracy of the results was evaluated using the false discovery rate (FDR) multiple correction method. Both heterogeneity and pleiotropy were evaluated by analyzing sensitivities.

RESULTS

According to the results of two-sample MR analyses, Alzheimer's disease significantly reduced the risks of overall (OR 0.925, 95% CI [0.871-0.982], P = 0.011) and ER+ (OR 0.912, 95% CI [0.853-0.975], P = 0.007) breast cancer, but there was a negative result in ER- breast cancer. However, after multiple FDR corrections, the effect of Alzheimer's disease on overall breast cancer was not statistically significant. In contrast, multiple sclerosis significantly increased ER+ breast cancer risk (OR 1.007, 95% CI [1.003-1.011], P = 0.001). In addition, the multivariable MR analyses showed that Alzheimer's disease significantly reduced the risk of ER+ breast cancer (IVW: OR 0.929, 95% CI [0.864-0.999], P=0.047; MR-Egger: OR 0.916, 95% CI [0.846-0.992], P=0.031); however, multiple sclerosis significantly increased the risk of ER+ breast cancer (IVW: OR 1.008, 95% CI [1.003-1.012], P=4.35×10-4; MR-Egger: OR 1.008, 95% CI [1.003-1.012], P=5.96×10-4). There were no significant associations between the remainder of the neurological diseases and breast cancer.

CONCLUSIONS

This study found the trends towards a decreased risk of ER+ breast cancer in patients with Alzheimer's disease and an increased risk in patients with multiple sclerosis. However, due to the limitations of Mendelian randomization, we cannot determine whether there are definite causal relationships between neurological diseases and breast cancer risk. For conclusive evidences, more prospective randomized controlled trials will be needed in the future.

Inference of drug off-target effects on cellular signaling using interactome-based deep learning

Many diseases emerge from dysregulated cellular signaling, and drugs are often designed to target specific signaling proteins. Off-target effects are, however, common and may ultimately result in failed clinical trials. Here we develop a computer model of the cell's transcriptional response to drugs for improved understanding of their mechanisms of action. The model is based on ensembles of artificial neural networks and simultaneously infers drug-target interactions and their downstream effects on intracellular signaling. With this, it predicts transcription factors' activities, while recovering known drug-target interactions and inferring many new ones, which we validate with an independent dataset. As a case study, we analyze the effects of the drug Lestaurtinib on downstream signaling. Alongside its intended target, FLT3, the model predicts an inhibition of CDK2 that enhances the downregulation of the cell cycle-critical transcription factor FOXM1. Our approach can therefore enhance our understanding of drug signaling for therapeutic design.

Lipoteichoic acid restrains macrophage senescence via β-catenin/FOXO1/REDD1 pathway in age-related osteoporosis

Osteoporosis and its related fractures are common causes of morbidity and mortality in older adults, but its underlying molecular and cellular mechanisms remain largely unknown. In this study, we found that lipoteichoic acid (LTA) treatment could ameliorate age-related bone degeneration and attenuate intramedullary macrophage senescence. FOXO1 signaling, which was downregulated and deactivated in aging macrophages, played a key role in the process. Blocking FOXO1 signaling caused decreased REDD1 expression and increased phosphorylation level of mTOR, a major driver of aging, as well as aggravated bone loss and deteriorated macrophage senescence. Moreover, LTA elevated FOXO1 signaling through β-catenin pathway while β-catenin inhibition significantly suppressed FOXO1 signaling, promoted senescence-related protein expression, and accelerated bone degeneration and macrophage senescence. Our findings indicated that β-catenin/FOXO1/REDD1 signaling plays a physiologically significant role that protecting macrophages from senescence during aging.

A common molecular and cellular pathway in developing Alzheimer and cancer

Globally cancer and Alzheimer's disease (AD) are two major diseases and still, there is no clearly defined molecular mechanism. There is an opposite relation between cancer and AD which are the proportion of emerging cancer was importantly slower in AD patients, whereas slow emerging AD in patients with cancer. In cancer, regulation of cell mechanisms is interrupted by an increase in cell survival and proliferation, while on the contrary, AD is related to augmented neuronal death, that may be either produced by or associated with amyloid-β (Aβ) and tau deposition. Stated that the probability that disruption of mechanisms takes part in the regulation of cell survival/death and might be implicated in both diseases. The mechanism of actions such as DNA-methylation, genetic polymorphisms, or another mechanism of actions that induce alteration in the action of drugs with significant roles in resolving the finding to repair and live or die might take part in the pathogenesis of these two ailments. The functions of miRNA, p53, Pin1, the Wnt signaling pathway, PI3 KINASE/Akt/mTOR signaling pathway GRK2 signaling pathway, and the pathophysiological role of oxidative stress are presented in this review as potential candidates which hypothetically describe inverse relations between cancer and AD. Innovative materials almost mutual mechanisms in the aetiology of cancer and AD advocates novel treatment approaches. Among these treatment strategies, the most promising use treatment such as tyrosine kinase inhibitor, nilotinib, protein kinase C, and bexarotene.

Consequences of Aging on Bone

With the aging of the global population, the incidence of musculoskeletal diseases has been increasing, seriously affecting people's health. As people age, the microenvironment within skeleton favors bone resorption and inhibits bone formation, accompanied by bone marrow fat accumulation and multiple cellular senescence. Specifically, skeletal stem/stromal cells (SSCs) during aging tend to undergo adipogenesis rather than osteogenesis. Meanwhile, osteoblasts, as well as osteocytes, showed increased apoptosis, decreased quantity, and multiple functional limitations including impaired mechanical sensing, intercellular modulation, and exosome secretion. Also, the bone resorption function of macrophage-lineage cells (including osteoclasts and preosteoclasts) was significantly enhanced, as well as impaired vascularization and innervation. In this study, we systematically reviewed the effect of aging on bone and the within microenvironment (including skeletal cells as well as their intracellular structure variations, vascular structures, innervation, marrow fat distribution, and lymphatic system) caused by aging, and mechanisms of osteoimmune regulation of the bone environment in the aging state, and the causal relationship with multiple musculoskeletal diseases in addition with their potential therapeutic strategy.

Comparative computational analysis to distinguish mesenchymal stem cells from fibroblasts

Introduction

Mesenchymal stem cells (MSCs) are considered to be the most promising stem cell type for cell-based therapies in regenerative medicine. Based on their potential to home to diseased body sites following a therapeutically application, these cells could (i) differentiate then into organ-specific cell types to locally restore injured cells or, most prominently, (ii) foster tissue regeneration including immune modulations more indirectly by secretion of protective growth factors and cytokines. As tissue-resident stem cells of mesenchymal origin, these cells are morphologically and even molecularly- at least concerning the classical marker genes- indistinguishable from similar lineage cells, particularly fibroblasts.

Methods

Here we used microarray-based gene expression and global DNA methylation analyses as well as accompanying computational tools in order to specify differences between MSCs and fibroblasts, to further unravel potential identity genes and to highlight MSC signaling pathways with regard to their trophic and immunosuppressive action.

Results

We identified 1352 differentially expressed genes, of which in the MSCs there is a strong signature for e.g., KRAS signaling, known to play essential role in stemness maintenance, regulation of coagulation and complement being decisive for resolving inflammatory processes, as well as of wound healing particularly important for their regenerative capacity. Genes upregulated in fibroblasts addressed predominately transcription and biosynthetic processes and mapped morphological features of the tissue. Concerning the cellular identity, we specified the already known HOX code for MSCs, established a potential HOX code for fibroblasts, and linked certain HOX genes to functional cell-type-specific properties. Accompanied methylation profiles revealed numerous regions, especially in HOX genes, being differentially methylated, which might provide additional biomarker potential.

Discussion

Conclusively, transcriptomic together with epigenetic signatures can be successfully be used for the definition (cellular identity) of MSCs versus fibroblasts as well as for the determination of the superior functional properties of MSCs, such as their immunomodulatory potential.

WNT-β Catenin Signaling as a Potential Therapeutic Target for Neurodegenerative Diseases: Current Status and Future Perspective

Wnt/β-catenin (WβC) signaling pathway is an important signaling pathway for the maintenance of cellular homeostasis from the embryonic developmental stages to adulthood. The canonical pathway of WβC signaling is essential for neurogenesis, cell proliferation, and neurogenesis, whereas the noncanonical pathway (WNT/Ca²⁺ and WNT/PCP) is responsible for cell polarity, calcium maintenance, and cell migration. Abnormal regulation of WβC signaling is involved in the pathogenesis of several neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and spinal muscular atrophy (SMA). Hence, the alteration of WβC signaling is considered a potential therapeutic target for the treatment of neurodegenerative disease. In the present review, we have used the bibliographical information from PubMed, Google Scholar, and Scopus to address the current prospects of WβC signaling role in the abovementioned neurodegenerative diseases.

Gut brain interaction theory reveals gut microbiota mediated neurogenesis and traditional Chinese medicine research strategies

Adult neurogenesis is the process of differentiation of neural stem cells (NSCs) into neurons and glial cells in certain areas of the adult brain. Defects in neurogenesis can lead to neurodegenerative diseases, mental disorders, and other maladies. This process is directionally regulated by transcription factors, the Wnt and Notch pathway, the extracellular matrix, and various growth factors. External factors like stress, physical exercise, diet, medications, etc., affect neurogenesis and the gut microbiota. The gut microbiota may affect NSCs through vagal, immune and chemical pathways, and other pathways. Traditional Chinese medicine (TCM) has been proven to affect NSCs proliferation and differentiation and can regulate the abundance and metabolites produced by intestinal microorganisms. However, the underlying mechanisms by which these factors regulate neurogenesis through the gut microbiota are not fully understood. In this review, we describe the recent evidence on the role of the gut microbiota in neurogenesis. Moreover, we hypothesize on the characteristics of the microbiota-gut-brain axis based on bacterial phyla, including microbiota's metabolites, and neuronal and immune pathways while providing an outlook on TCM's potential effects on adult neurogenesis by regulating gut microbiota.

Arterial Stiffness and the Canonical WNT/β-catenin Pathway

PURPOSE OF REVIEW

Arterial stiffness (AS) was mainly associated with cardiovascular morbidity and mortality in a hypertensive patient. Some risk factors contribute to the development of AS, such as aging, high blood pressure, vascular calcification, inflammation, and diabetes mellitus. The WNT/β-catenin pathway is implicated in numerous signaling and regulating pathways, including embryogenesis, cell proliferation, migration and polarity, apoptosis, and organogenesis. The activation of the WNT/β-catenin pathway is associated with the development of these risk factors.

RECENT FINDINGS

Aortic pulse wave velocity (PWV) is measured to determine AS, and in peripheral artery disease patients, PWV is higher than controls. An augmentation in PWV by 1 m/s has been shown to increase the risk of cardiovascular events by 14%. AS measured by PWV is characterized by the deregulation of the WNT/β-catenin pathway by the inactivation of its two inhibitors, i.e., DKK1 and sclerostin. Thus, this review focuses on the role of the WNT/β-catenin pathway which contributes to the development of arterial stiffness.

Aging the brain: multi-region methylation principal component based clock in the context of Alzheimer's disease

Alzheimer's disease (AD) risk increases exponentially with age and is associated with multiple molecular hallmarks of aging, one of which is epigenetic alterations. Epigenetic age predictors based on 5' cytosine methylation (DNAm), or epigenetic clocks, have previously suggested that epigenetic age acceleration may occur in AD brain tissue. Epigenetic clocks are promising tools for the quantification of biological aging, yet we hypothesize that investigation of brain aging in AD will be assisted by the development of brain-specific epigenetic clocks. Therefore, we generated a novel age predictor termed PCBrainAge that was trained solely in cortical samples. This predictor utilizes a combination of principal components analysis and regularized regression, which reduces technical noise and greatly improves test-retest reliability. To characterize the scope of PCBrainAge's utility, we generated DNAm data from multiple brain regions in a sample from the Religious Orders Study and Rush Memory and Aging Project. PCBrainAge captures meaningful heterogeneity of aging: Its acceleration demonstrates stronger associations with clinical AD dementia, pathologic AD, and APOE ε4 carrier status compared to extant epigenetic age predictors. It further does so across multiple cortical and subcortical regions. Overall, PCBrainAge's increased reliability and specificity makes it a particularly promising tool for investigating heterogeneity in brain aging, as well as epigenetic alterations underlying AD risk and resilience.

Age- and Sex-Associated Glucose Metabolism Decline in a Mouse Model of Alzheimer’s Disease

Background: Alzheimer’s disease (AD) is characterized by a high etiological and clinical heterogeneity, which has obscured the diagnostic and treatment efficacy, as well as limited the development of potential drugs. Sex differences are among the risk factors that contribute to the variability of disease manifestation. Unlike men, women are at greater risk of developing AD and suffer from higher cognitive deterioration, together with important changes in pathological features. Alterations in glucose metabolism are emerging as a key player in the pathogenesis of AD, which appear even decades before the presence of clinical symptoms. Objective: We aimed to study whether AD-related sex differences influence glucose metabolism. Methods: We used male and female APPswe/PS1dE9 (APP/PS1) transgenic mice of different ages to examine glucose metabolism effects on AD development. Results: Our analysis suggests an age-dependent decline of metabolic responses, cognitive functions, and brain energy homeostasis, together with an increase of Aβ levels in both males and females APP/PS1 mice. The administration of Andrographolide (Andro), an anti-inflammatory and anti-diabetic compound, was able to restore several metabolic disturbances, including the glycolytic and the pentose phosphate pathway fluxes, ATP levels, AMPKα activity, and Glut3 expression in 8-month-old mice, independent of the sex, while rescuing these abnormalities only in older females. Similarly, Andro also prevented Aβ accumulation and cognitive decline in all but old males. Conclusion: Our study provides insight into the heterogeneity of the disease and supports the use of Andro as a potential drug to promote personalized medicine in AD.

"Reframing" dopamine signaling at the intersection of glial networks in the aged Parkinsonian brain as innate Nrf2/Wnt driver: Therapeutical implications

Dopamine (DA) signaling via G protein-coupled receptors is a multifunctional neurotransmitter and neuroendocrine-immune modulator. The DA nigrostriatal pathway, which controls the motor coordination, progressively degenerates in Parkinson's disease (PD), a most common neurodegenerative disorder (ND) characterized by a selective, age-dependent loss of substantia nigra pars compacta (SNpc) neurons, where DA itself is a primary source of oxidative stress and mitochondrial impairment, intersecting astrocyte and microglial inflammatory networks. Importantly, glia acts as a preferential neuroendocrine-immune DA target, in turn, counter-modulating inflammatory processes. With a major focus on DA intersection within the astrocyte-microglial inflammatory network in PD vulnerability, we herein first summarize the characteristics of DA signaling systems, the propensity of DA neurons to oxidative stress, and glial inflammatory triggers dictating the vulnerability to PD. Reciprocally, DA modulation of astrocytes and microglial reactivity, coupled to the synergic impact of gene-environment interactions, then constitute a further level of control regulating midbrain DA neuron (mDAn) survival/death. Not surprisingly, within this circuitry, DA converges to modulate nuclear factor erythroid 2-like 2 (Nrf2), the master regulator of cellular defense against oxidative stress and inflammation, and Wingless (Wnt)/β-catenin signaling, a key pathway for mDAn neurogenesis, neuroprotection, and immunomodulation, adding to the already complex "signaling puzzle," a novel actor in mDAn-glial regulatory machinery. Here, we propose an autoregulatory feedback system allowing DA to act as an endogenous Nrf2/Wnt innate modulator and trace the importance of DA receptor agonists applied to the clinic as immune modifiers.

Inverse Correlation Between Alzheimer's Disease and Cancer: Short Overview

The negative association between Alzheimer's disease (AD) and cancer suggests that susceptibility to one disease may protect against the other. When biological mechanisms of AD and cancer and relationship between them are understood, the unsolved problem of both diseases which still touches the growing human population could be overcome. Actual information about biological mechanisms and common risk factors such as chronic inflammation, age-related metabolic deregulation, and family history is presented here. Common signaling pathways, e.g., p53, Wnt, role of Pin1, and microRNA, are discussed as well. Much attention is also paid to the potential impact of chronic viral, bacterial, and fungal infections that are responsible for the inflammatory pathway in AD and also play a key role to cancer development. New data about common mechanisms in etiopathology of cancer and neurological diseases suggests new therapeutic strategies. Among them, the use of nilotinib, tyrosine kinase inhibitor, protein kinase C, and bexarotene is the most promising.

Attenuative Effects of Fluoxetine and Triticum aestivum against Aluminum-Induced Alzheimer's Disease in Rats: The Possible Consequences on Hepatotoxicity and Nephrotoxicity

BACKGROUND

Alzheimer's disease (AD) is a chronic neurological illness that causes considerable cognitive impairment. Hepatic and renal dysfunction may worsen AD by disrupting β-amyloid homeostasis at the periphery and by causing metabolic dysfunction. Wheatgrass (Triticum aestivum) has been shown to have antioxidant and anti-inflammatory properties. This work aims to study the effect of aluminum on neuronal cells, its consequences on the liver and kidneys, and the possible role of fluoxetine and wheatgrass juice in attenuating these pathological conditions.

METHOD

Rats were divided into five groups. Control, AD (AlCl₃), Fluoxetine (Fluoxetine and AlCl₃), Wheatgrass (Wheatgrass and AlCl₃), and combination group (fluoxetine, wheatgrass, and AlCl₃). All groups were assigned daily to different treatments for five weeks.

CONCLUSIONS

AlCl₃ elevated liver and kidney enzymes, over-production of oxidative stress, and inflammatory markers. Besides, accumulation of tau protein and Aβ, the elevation of ACHE and GSK-3β, down-regulation of BDNF, and β-catenin expression in the brain. Histopathological examinations of the liver, kidney, and brain confirmed this toxicity, while treating AD groups with fluoxetine, wheatgrass, or a combination alleviates toxic insults.

CONCLUSION

Fluoxetine and wheatgrass combination demonstrated a more significant neuroprotective impact in treating AD than fluoxetine alone and has protective effects on liver and kidney tissues.

Targeting Wnt signaling pathway by polyphenols: implication for aging and age-related diseases

Age is an important risk factor for different diseases. The same mechanisms that promote aging are involved in the development and progression of age-associated diseases. Polyphenols are organic compounds found in fruits and vegetables. Due to their beneficial properties (e.g. antioxidant and anti-inflammatory), polyphenols have been extensively used for treating chronic diseases. To exert their functions, polyphenols target various molecular mechanisms and signaling pathways, such as mTOR, NF-κB, and Wnt/β-catenin. Wnt signaling is a critical pathway for developmental processes. Besides, dysregulation of this signaling pathway has been observed in various diseases. Several investigations have been conducted on Wnt inhibitors at pre-clinical stages, showing promising results. Herein, we review the studies dealing with the role of polyphenols in targeting the Wnt signaling pathways in aging processes and age-associated diseases, including cancer, diabetes, Alzheimer's disease, osteoporosis, and Parkinson's disease.

WNT10A induces apoptosis of senescent synovial resident stem cells through Wnt/calcium pathway-mediated HDAC5 phosphorylation in OA joints

Recently, the accumulation of senescent cells (SnCs) within joints was found to promote osteoarthritis (OA) progression. Our previous study found that Wnt proteins, especially Wnt10a, have marked effects on cellular senescence and joint health. However, the effect of WNT10A on SnCs in OA joints remains unknown. In this study, we confirmed that the synovium was the first and most marked site of SnC accumulation in the OA joint, and synovial resident mesenchymal stem cells (SMSCs) seemed to be the main source of these SnCs. In synovium samples from OA patients, WNT10A level inversely correlated with the extent of SnCs accumulation. Therefore, we further explored the possible regulatory role and mechanism of WNT10A in intraarticular senescent SMSCs. In brief, we confirmed that WNT10A could specifically clear these senescent OA-SMSCs in vitro experiments and naturally occurring OA models via proapoptotic effects. Mechanistically, WNT10A activated noncanonical Wnt/calcium signaling in senescent OA-SMSCs, which in turn induced histone deacetylase 5 (HDAC5) phosphorylation and nuclear export via its downstream Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) to regulate cell fate. The regulation of this pathway significantly improved the regenerative microenvironment of OA, exhibiting its potential as a novel clinical disease-modifying OA drugs (DMOADs) target.

LncRNA-HAGLR motivates triple negative breast cancer progression by regulation of WNT2 via sponging miR-335-3p

Background: Triple negative breast cancer (TNBC) is a group of highly heterogeneous mixed breast cancer at the level of gene expression profile. Therefore, it is of great clinical significance to explore the molecular mechanism of TNBC and find a targeted therapeutic approach from the molecular level.

Methods: Long non-coding RNA (lncRNA) HAGLR expression level was measured by and qRT-PCR in TNBC tissues and cell lines. EdU, MTT, wound healing and Transwell assays were performed to explore the role of HAGLR on the malignancy of TNBC cells. Luciferase assay was used to clarify the binding between miR-335-3p with HAGLR and WNT2. The tumor formation experiment in nude mice was used to explore the function of HAGLR in vivo.

Results: HAGLR was increased in TNBC tissues and cell lines. Silencing of HAGLR inhibited viability, proliferation, migration, and invasion of BT549 cells. Furthermore, HAGLR acted as a sponge of miR-335-3p and inhibited its expression. And miR-335-3p directly targeted WNT2. Functionally, forced expression of miR-335-3p or knockdown of WNT2 removed the promoted effects of lncRNA HAGLR on TNBC development. In vivo tumorigenesis experiments indicated HAGLR accelerated tumor growth via miR-335-3p/WNT2 axis.

Conclusion: Our study revealed that HAGLR promoted the growth of TNBC, which was mediated by miR-335-3p/WNT2 axis.

The transcriptional landscape of Alzheimer's disease and its association with Wnt signaling pathway

Alzheimer's disease (AD) is a neurological disorder primarily affecting the elderly. The disease manifests as progressive deterioration in cognitive functions, leading to a loss of autonomy. The identification of transcriptional changes in susceptible signaling pathways has provided clues to the origin and progression of AD and has pinpointed synapse loss as the prominent event in early stages of the disease. Synapse failure represents a key pathological correlate of cognitive decline in patients. Genetics and transcriptomics studies have also identified novel genes, processes, and pathways associated with AD. This evidence suggests that a deficiency in Wnt signaling pathway contributes to AD pathogenesis by inducing synaptic dysfunction and neuronal degeneration. In the adult nervous system, Wnt signaling plays a crucial role in synaptic physiology, modulating the synaptic vesicle cycle, trafficking neurotransmitter receptors, and modulating the expression of different genes associated with these processes. In this review, we describe the general transcriptional landscape associated with AD, specifically transcriptional changes associated with the Wnt signaling pathway and their effects in the context of disease.

WNT Signaling Is a Key Player in Alzheimer's Disease

The cellular processes regulated by WNT signaling have been mainly studied during embryonic development and cancer. In the last two decades, the role of WNT in the adult central nervous system has been the focus of interest in our laboratory. In this chapter, we will be summarized β-catenin-dependent and -independent WNT pathways, then we will be revised WNT signaling function at the pre- and post-synaptic level. Concerning Alzheimer's disease (AD) initially, we found that WNT/β-catenin signaling activation exerts a neuroprotective mechanism against the amyloid β (Αβ) peptide toxicity. Later, we found that WNT/β-catenin participates in Tau phosphorylation and in learning and memory. In the last years, we demonstrated that WNT/β-catenin signaling is instrumental in the amyloid precursor protein (APP) processing and that WNT/β-catenin dysfunction results in Aβ production and aggregation. We highlight the importance of WNT/β-catenin signaling dysfunction in the onset of AD and propose that the loss of WNT/β-catenin signaling is a triggering factor of AD. The WNT pathway is therefore positioned as a therapeutic target for AD and could be a valid concept for improving AD therapy. We think that metabolism and inflammation will be relevant when defining future research in the context of WNT signaling and the neurodegeneration associated with AD.

Dysregulated Wnt Signalling in the Alzheimer's Brain

The Wnt signalling system is essential for both the developing and adult central nervous system. It regulates numerous cellular functions ranging from neurogenesis to blood brain barrier biology. Dysregulated Wnt signalling can thus have significant consequences for normal brain function, which is becoming increasingly clear in Alzheimer's disease (AD), an age-related neurodegenerative disorder that is the most prevalent form of dementia. AD exhibits a range of pathophysiological manifestations including aberrant amyloid precursor protein processing, tau pathology, synapse loss, neuroinflammation and blood brain barrier breakdown, which have been associated to a greater or lesser degree with abnormal Wnt signalling. Here we provide a comprehensive overview of the role of Wnt signalling in the CNS, and the research that implicates dysregulated Wnt signalling in the ageing brain and in AD pathogenesis. We also discuss the opportunities for therapeutic intervention in AD via modulation of the Wnt signalling pathway, and highlight some of the challenges and the gaps in our current understanding that need to be met to enable that goal.

Nrf2/Wnt resilience orchestrates rejuvenation of glia-neuron dialogue in Parkinson's disease

Oxidative stress and inflammation have long been recognized to contribute to Parkinson's disease (PD), a common movement disorder characterized by the selective loss of midbrain dopaminergic neurons (mDAn) of the substantia nigra pars compacta (SNpc). The causes and mechanisms still remain elusive, but a complex interplay between several genes and a number of interconnected environmental factors, are chiefly involved in mDAn demise, as they intersect the key cellular functions affected in PD, such as the inflammatory response, mitochondrial, lysosomal, proteosomal and autophagic functions. Nuclear factor erythroid 2 -like 2 (NFE2L2/Nrf2), the master regulator of cellular defense against oxidative stress and inflammation, and Wingless (Wnt)/β-catenin signaling cascade, a vital pathway for mDAn neurogenesis and neuroprotection, emerge as critical intertwinned actors in mDAn physiopathology, as a decline of an Nrf2/Wnt/β-catenin prosurvival axis with age underlying PD mutations and a variety of noxious environmental exposures drive PD neurodegeneration. Unexpectedly, astrocytes, the so-called "star-shaped" cells, harbouring an arsenal of "beneficial" and "harmful" molecules represent the turning point in the physiopathological and therapeutical scenario of PD. Fascinatingly, "astrocyte's fil rouge" brings back to Nrf2/Wnt resilience, as boosting the Nrf2/Wnt resilience program rejuvenates astrocytes, in turn (i) mitigating nigrostriatal degeneration of aged mice, (ii) reactivating neural stem progenitor cell proliferation and neuron differentiation in the brain and (iii) promoting a beneficial immunomodulation via bidirectional communication with mDAns. Then, through resilience of Nrf2/Wnt/β-catenin anti-ageing, prosurvival and proregenerative molecular programs, it seems possible to boost the inherent endogenous self-repair mechanisms. Here, the cellular and molecular aspects as well as the therapeutical options for rejuvenating glia-neuron dialogue will be discussed together with major glial-derived mechanisms and therapies that will be fundamental to the identification of novel diagnostic tools and treatments for neurodegenerative diseases (NDs), to fight ageing and nigrostriatal DAergic degeneration and promote functional recovery.

Wnt Signaling Pathway Dysregulation in the Aging Brain: Lessons From the Octodon degus

Wnt signaling constitutes a fundamental cellular and molecular pathway, necessary from proper embryogenesis to function-maintenance of fully developed complex organisms. In this regard, Wnt pathway plays a crucial role in both the development of the central nervous system and in maintaining the structure and function of the neuronal circuits, and it has been suggested that its dysregulation is critical in the onset of several pathologies including cancer and neurodegenerative disorders, such as Alzheimer's disease (AD). Due to its relevance in the maintenance of the neuronal activity and its involvement in the outbreak of devastating diseases, we explored the age-related changes in the expression of Wnt key components in the cortex and hippocampus of 7 to 72-months-old Octodon degus (O. degus), a Chilean long-living endemic rodent that has been proposed and used as a natural model for AD. We found a down-regulation in the expression of different Wnt ligands (Wnt3a, Wnt7a, and Wnt5a), as well as in the Wnt co-receptor LRP6. We also observed an increase in the activity of GSK-3β related to the down-regulation of Wnt activity, a fact that was confirmed by a decreased expression of Wnt target genes. Relevantly, an important increase was found in secreted endogenous Wnt inhibitors, including the secreted-frizzled-related protein 1 and 2 (SFRP-1 and SFRP-2) and Dickkopf-1 (Dkk-1), all them antagonists at the cell surface. Furthermore, treatment with Andrographolide, a labdane diterpene obtained from Andrographis paniculata, prevents Wnt signaling loss in aging degus. Taken together, these results suggest that during the aging process Wnt signaling activity decreases in the brain of O. degus.

Effect of Active Ingredients of Chinese Herbal Medicine on the Rejuvenation of Healthy Aging: Focus on Stem Cells

Stem cells (SCs) are special types of cells with the ability of self-renewal and multidirectional differentiation. As the organism ages, the ability to maintain homeostasis and regeneration deteriorates and the number and activity of stem cells decline. Theoretically, the restoration of stem cells might reverse aging. However, due to their own aging, donor-derived immune rejection, and difficulties in stem cell differentiation control, a series of problems need to be solved to realize the potential for clinical application of stem cells. Chinese herbal medicine is a nature drug library which is suitable for the long-term treatment of aging-related diseases. Modern pharmacological studies have revealed that many active ingredients of Chinese herbal medicines with the effect of promoting stem cells growth and differentiation mainly belong to “reinforcing herbs.” In recent years, exploration of natural active ingredients from Chinese herbal medicines for delaying aging, improving the stem cell microenvironment, and promoting the proliferation and differentiation of endogenous stem cells has attracted substantial attention. This article will focus on active ingredients from Chinese herbs-mediated differentiation of stem cells into particular cell type, like neural cells, endothelial cells, cardiomyocytes, and osteoblasts. We will also discuss the effects of these small molecules on Wnt, Sonic Hedgehog, Notch, eNOS-cGMP, and MAP kinase signal transduction pathways, as well as reveal the role of estrogen receptor α and PPAR γ on selectively promoting or inhibiting stem cells differentiation. This review will provide new insights into the health aging strategies of active ingredients in Chinese herbal medicine in regenerative medicine.

Boosting Antioxidant Self-defenses by Grafting Astrocytes Rejuvenates the Aged Microenvironment and Mitigates Nigrostriatal Toxicity in Parkinsonian Brain via an Nrf2-Driven Wnt/β-Catenin Prosurvival Axis

Astrocyte (As) bidirectional dialog with neurons plays a fundamental role in major homeostatic brain functions, particularly providing metabolic support and antioxidant self-defense against reactive oxygen (ROS) and nitrogen species (RNS) via the activation of NF-E2-related factor 2 (Nrf2), a master regulator of oxidative stress. Disruption of As-neuron crosstalk is chiefly involved in neuronal degeneration observed in Parkinson's disease (PD), the most common movement disorder characterized by the selective degeneration of dopaminergic (DAergic) cell bodies of the substantia nigra (SN) pars compacta (SNpc). Ventral midbrain (VM)-As are recognized to exert an important role in DAergic neuroprotection via the expression of a variety of factors, including wingless-related MMTV integration site 1 (Wnt1), a principal player in DAergic neurogenesis. However, whether As, by themselves, might fulfill the role of chief players in DAergic neurorestoration of aged PD mice is presently unresolved. Here, we used primary postnatal mouse VM-As as a graft source for unilateral transplantation above the SN of aged 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mice after the onset of motor symptoms. Spatio-temporal analyses documented that the engrafted cells promoted: (i) a time-dependent nigrostriatal rescue along with increased high-affinity synaptosomal DA uptake and counteraction of motor deficit, as compared to mock-grafted counterparts; and (ii) a restoration of the impaired microenvironment via upregulation of As antioxidant self-defense through the activation of Nrf2/Wnt/β-catenin signaling, suggesting that grafting As has the potential to switch the SN neurorescue-unfriendly environment to a beneficial antioxidant/anti-inflammatory prosurvival milieu. These findings highlight As-derived factors/mechanisms as the crucial key for successful therapeutic outcomes in PD.

Parkinson's disease, aging and adult neurogenesis: Wnt/β-catenin signalling as the key to unlock the mystery of endogenous brain repair

A common hallmark of age-dependent neurodegenerative diseases is an impairment of adult neurogenesis. Wingless-type mouse mammary tumor virus integration site (Wnt)/β-catenin (WβC) signalling is a vital pathway for dopaminergic (DAergic) neurogenesis and an essential signalling system during embryonic development and aging, the most critical risk factor for Parkinson's disease (PD). To date, there is no known cause or cure for PD. Here we focus on the potential to reawaken the impaired neurogenic niches to rejuvenate and repair the aged PD brain. Specifically, we highlight WβC-signalling in the plasticity of the subventricular zone (SVZ), the largest germinal region in the mature brain innervated by nigrostriatal DAergic terminals, and the mesencephalic aqueduct-periventricular region (Aq-PVR) Wnt-sensitive niche, which is in proximity to the SNpc and harbors neural stem progenitor cells (NSCs) with DAergic potential. The hallmark of the WβC pathway is the cytosolic accumulation of β-catenin, which enters the nucleus and associates with T cell factor/lymphoid enhancer binding factor (TCF/LEF) transcription factors, leading to the transcription of Wnt target genes. Here, we underscore the dynamic interplay between DAergic innervation and astroglial-derived factors regulating WβC-dependent transcription of key genes orchestrating NSC proliferation, survival, migration and differentiation. Aging, inflammation and oxidative stress synergize with neurotoxin exposure in "turning off" the WβC neurogenic switch via down-regulation of the nuclear factor erythroid-2-related factor 2/Wnt-regulated signalosome, a key player in the maintenance of antioxidant self-defense mechanisms and NSC homeostasis. Harnessing WβC-signalling in the aged PD brain can thus restore neurogenesis, rejuvenate the microenvironment, and promote neurorescue and regeneration.

Dysregulation of the Wnt Signaling Pathway and Synovial Stem Cell Dysfunction in Osteoarthritis Development

Stem cell dysfunction and failure have been found in joints afflicted by osteoarthritis (OA). However, the exact factors in the OA microenvironment that impair stem cell functions and the role of stem cell dysfunction in OA development have not been fully clarified. In this study, we evaluated the functional status of synovial mesenchymal stem cells (SMSCs) from OA patients and explored the influence of OA-SMSCs on cartilage degradation in a rat model. We then screened 138 Wnt signaling-related genes in the synovium of OA patients, focusing on the effects of five WNT ligands on SMSC functions. The OA synovium showed mild hyperplasia, and we found a large number of CD90⁺/CD105⁺ stem cells in synovial hyperplasia. The OA-SMSCs revealed a cellular senescence phenotype, with decreased proliferation and chondrogenic capacity, accompanied by enhanced migration, proinflammatory and matrix degradation activities. The intra-articular transplantation of these OA-SMSCs significantly aggravated the degradation and destruction of the articular cartilage. Of 138 Wnt signaling genes, the expression of 86 genes was consistently altered in the OA synovium, among which the increased expression of DVL2, WNT10A, and DKK3 was the most marked. In general, we found that canonical Wnt/β-catenin pathways were inhibited in the OA synovium, whereas noncanonical PCP and Wnt/Ca2⁺ pathways were activated. In vitro, WNT10A had an obvious antisenescence effect on SMSCs. WNT5B significantly inhibited the chondrogenic differentiation of SMSCs, and WNT10A and WNT5A increased the expression of inflammatory cytokines in SMSCs. In a rat model, WNT5A significantly aggravated joint degeneration, whereas WNT10A had a mild protective effect on cartilage integrity. In conclusion, stem cells in the OA synovium were functionally abnormal and promoted the development of OA, whereas dysregulation of the Wnt signaling pathway revealed a comprehensive influence on SMSC functions and cartilage degradation.

Restoring Wnt/β-catenin signaling is a promising therapeutic strategy for Alzheimer's disease

Alzheimer’s disease (AD) is an aging-related neurological disorder characterized by synaptic loss and dementia. Wnt/β-catenin signaling is an essential signal transduction pathway that regulates numerous cellular processes including cell survival. In brain, Wnt/β-catenin signaling is not only crucial for neuronal survival and neurogenesis, but it plays important roles in regulating synaptic plasticity and blood-brain barrier integrity and function. Moreover, activation of Wnt/β-catenin signaling inhibits amyloid-β production and tau protein hyperphosphorylation in the brain. Critically, Wnt/β-catenin signaling is greatly suppressed in AD brain via multiple pathogenic mechanisms. As such, restoring Wnt/β-catenin signaling represents a unique opportunity for the rational design of novel AD therapies.

Glioblastoma cells vampirize WNT from neurons and trigger a JNK/MMP signaling loop that enhances glioblastoma progression and neurodegeneration

Glioblastoma (GB) is the most lethal brain tumor, and Wingless (Wg)-related integration site (WNT) pathway activation in these tumors is associated with a poor prognosis. Clinically, the disease is characterized by progressive neurological deficits. However, whether these symptoms result from direct or indirect damage to neurons is still unresolved. Using Drosophila and primary xenografts as models of human GB, we describe, here, a mechanism that leads to activation of WNT signaling (Wg in Drosophila) in tumor cells. GB cells display a network of tumor microtubes (TMs) that enwrap neurons, accumulate Wg receptor Frizzled1 (Fz1), and, thereby, deplete Wg from neurons, causing neurodegeneration. We have defined this process as "vampirization." Furthermore, GB cells establish a positive feedback loop to promote their expansion, in which the Wg pathway activates cJun N-terminal kinase (JNK) in GB cells, and, in turn, JNK signaling leads to the post-transcriptional up-regulation and accumulation of matrix metalloproteinases (MMPs), which facilitate TMs' infiltration throughout the brain, TMs' network expansion, and further Wg depletion from neurons. Consequently, GB cells proliferate because of the activation of the Wg signaling target, β-catenin, and neurons degenerate because of Wg signaling extinction. Our findings reveal a molecular mechanism for TM production, infiltration, and maintenance that can explain both neuron-dependent tumor progression and also the neural decay associated with GB.

Cav 1.2 regulates osteogenesis of bone marrow-derived mesenchymal stem cells via canonical Wnt pathway in age-related osteoporosis

Aims

Age‐related bone mass loss is one of the most prevalent diseases that afflict the elderly population. The decline in the osteogenic differentiation capacity of bone marrow‐derived mesenchymal stem cells (BMMSCs) is regarded as one of the central mediators. Voltage‐gated Ca²⁺ channels (VGCCs) play an important role in the regulation of various cell biological functions, and disruption of VGCCs is associated with several age‐related cellular characteristics and systemic symptoms. However, whether and how VGCCs cause the decreased osteogenic differentiation abilities of BMMSCs have not been fully elucidated.

Methods

Voltage‐gated Ca²⁺ channels related genes were screened, and the candidate gene was determined in several aging models. Functional role of determined channel on osteogenic differentiation of BMMSCs was investigated through gain and loss of function experiments. Molecular mechanism was explored, and intervention experiments in vivo and in vitro were performed.

Results

We found that Ca_v1.2 was downregulated in these aging models, and downregulation of Ca_v1.2 in Zmpste24−/− BMMSCs contributed to compromised osteogenic capacity. Mechanistically, Ca_v1.2 regulated the osteogenesis of BMMSCs through canonical Wnt/β‐catenin pathway. Moreover, upregulating the activity of Ca_v1.2 mitigated osteoporosis symptom in Zmpste24−/− mice.

Conclusion

Impaired osteogenic differentiation of Zmpste24−/− BMMSCs can be partly attributed to the decreased Ca_v1.2 expression, which leads to the inhibition of canonical Wnt pathway. Bay K8644 treatment could be an applicable approach for treating age‐related bone loss by ameliorating compromised osteogenic differentiation capacity through targeting Ca_v1.2 channel.

Wnt Signaling Deregulation in the Aging and Alzheimer's Brain

Growing evidence suggests that synaptic signaling is compromised in the aging brain and in Alzheimer’s disease (AD), contributing to synaptic decline. Wnt signaling is a prominent pathway at the synapse and is required for synaptic plasticity and maintenance in the adult brain. In this review, we summarize the current knowledge on deregulation of Wnt signaling in the context of aging and AD. Emerging studies suggest that enhancing Wnt signaling could boost synaptic function during aging, and ameliorate synaptic pathology in AD. Although further research is needed to determine the precise contribution of deficient Wnt signaling to AD pathogenesis, targeting Wnt signaling components may provide novel therapeutic avenues for synapse protection or restoration in the brain.

Conditional Haploinsufficiency of β-Catenin Aggravates Neuronal Damage in a Paraquat-Based Mouse Model of Parkinson Disease

The canonical Wnt pathway is critical for both the development and adulthood survival and homeostatic maintenance of the midbrain dopaminergic (DA) neurons. Expanding evidence has demonstrated that genetic factors associated with familial Parkinson disease (PD) deregulate this important pathway, suggesting that a disturbed canonical Wnt pathway is likely involved in PD pathogenesis; yet, the specific role of this pathway in sporadic PD remains unclear. In this study, we aimed to determine the effects of specific inhibition of the canonical pathway by hemizygous knockout of β-catenin, the obligatory component of the canonical Wnt pathway, on paraquat (PQ)-induced DA neuronal degeneration in the substantia nigra in vivo. We found that while hemizygous conditional knockout of β-catenin in DA neurons did not cause any significant TH+ neuronal loss in the substantia nigra at basal level, it triggered elevated oxidative stress at basal level and further enhanced PQ-induced oxidative damage and loss of TH+ neurons in the substantia nigra and axonal termini in the striatum that manifested as exacerbated motor deficits. These data support the notion that reduced Wnt/β-catenin signaling in sporadic PD likely contributes to DA neuronal loss through an enhanced oxidative stress-response pathway.

Deficient Wnt Signaling and Synaptic Vulnerability in Alzheimer's Disease: Emerging Roles for the LRP6 Receptor

Synapse dysfunction and loss represent critical early events in the pathophysiology of Alzheimer’s disease (AD). While extensive research has elucidated the direct synaptotoxic effects of Amyloid-β (Aβ) oligomers, less is known about how signaling pathways at the synapse are affected by Aβ. A better understanding of the cellular and molecular mechanisms underlying synaptic vulnerability in AD is key to illuminating the determinants of AD susceptibility and will unveil novel therapeutic avenues. Canonical Wnt signaling through the Wnt co-receptor LRP6 has a critical role in maintaining the structural and functional integrity of synaptic connections in the adult brain. Accumulating evidence suggests that deficient Wnt signaling may contribute to AD pathology. In particular, LRP6 deficiency compromises synaptic function and stability, and contributes to Aß production and plaque formation. Here, we review the role of Wnt signaling for synaptic maintenance in the adult brain and the contribution of aberrant Wnt signaling to synaptic degeneration in AD. We place a focus on emerging evidence implicating the LRP6 receptor as an important modulator of AD risk and pathology.

Regulatory Mechanisms of the Wnt/β-Catenin Pathway in Diabetic Cutaneous Ulcers

Skin ulcers are a serious complication of diabetes. Diabetic patients suffer from vascular lesions and complications such as peripheral neuritis, peripheral vascular lesions, and collagen abnormalities, which result in skin wounds that are refractory and often develop into chronic ulcers. The healing of skin ulcers requires an inflammatory reaction, wound proliferation, remodeling regulation, and control of stem cells. Studies investigating diabetic cutaneous ulcers have focused on cellular and molecular levels. Diabetes can cause nerve and blood vessel damage, and persistent high blood sugar levels can cause systemic multisite nerve damage based on peripheral neuropathy. The long-term hyperglycemia state enables the polyol glucose metabolism pathway to be activated, increasing the accumulation of toxic substances in the vascular injured nerve tissue cells. Sustained hyperglycemia leads to dysfunction of epithelial cells, leading to a decrease in pro-angiogenic signaling and nitric oxide production. In addition, due to impaired leukocyte function in hyperglycemia, immune function is impaired and the immune response at relevant sites is insufficient, making diabetic foot more difficult to heal. The Wnt/β-catenin pathway is a highly conserved signal transduction pathway involved in a variety of biological processes, such as cell proliferation, apoptosis, and differentiation. It is considered an important pathway involved in the healing of skin wounds. This article summarizes the mechanism of action of the Wnt/β-catenin pathway involved in the inflammatory responses to diabetic ulcers, wound proliferation, wound remodeling, and stem cells. The interactions between the Wnt signal pathway and other metabolic pathways are also discussed.

Wnt signaling in bone, kidney, intestine, and adipose tissue and interorgan interaction in aging

Over the last two decades, it has become increasingly apparent that Wnt signaling plays a critical role in development and adult tissue homeostasis in multiple organs and in the pathogenesis of many diseases. In particular, a crucial role for Wnt signaling in bone development and bone tissue homeostasis has been well recognized. Numerous genome-wide association studies confirmed the importance of Wnt signaling in controlling bone mass. Moreover, ample evidence suggests that Wnt signaling is essential for kidney, intestine, and adipose tissue development and homeostasis. Recent emerging evidence demonstrates that Wnt signaling may play a fundamental role in the aging process of those organs. New discoveries show that bone is not only the major reservoir for calcium and phosphate storage, but also the largest organ with multiple functions, including mineral and energy metabolism. The interactions among bone, kidney, intestine, and adipose tissue are controlled and regulated by several endocrine signals, including FGF23, klotho, sclerostin, osteocalcin, vitamin D, and leptin. Since the aging process is characterized by structural and functional decline in almost all tissues and organs, understanding the Wnt signaling-related interactions among bone, kidney, intestine, and adipose tissue in aging may shed light on the pathogenesis of age-related diseases.

Analysis of gene expression profiles of CR80, a neuroprotective 1,8-Naphthyridine

Aim: The 1,8-naphthyridine CR80 (ethyl 5-amino-2-methyl-6,7,8,9-tetrahydrobenzo[b] [1,8]naphthyridine-3-carboxylate) has shown interesting neuroprotective properties in in vitro and in vivo models of neurodegeneration. In spite of these promising outcomes, the molecular and cellular mechanisms underlying CR80 actions need to be further explored. Materials & methods: We herein report the signal transduction pathways involved in developmental, neuroprotective and stress-activated processes, as well as the gene expression regulation by CR80 in SH-SY5Y neuroblastoma cells. Results: The CR80 exposure upregulated several antioxidant enzymes (HO-1, GSR, SQSTM1, and TRXR1) and anti-apoptotic proteins (Bcl-xL, Bcl-2, P21, and Wnt6). Conclusion: The observed changes in gene expression would afford new insights on the neuroprotective profile of CR80.

Impaired Wnt Signaling in the Prefrontal Cortex of Alzheimer's Disease

Wnt pathway is involved in synaptic plasticity and neuronal survival, and alterations in Wnt signaling have previously been reported both in aging and neurodegenerative diseases, including Alzheimer's disease (AD). This study sought to evaluate Wnt signaling pathway interplay integrity across prefrontal lobe structures in AD patients compared to normal aging. Using the open-access BrainCloud™ database, 84 gene expression profiles and clustering effect were analyzed in the dorsomedial prefrontal cortex (PFC) across a time span of 21-78 years of age. Next, expression levels of the selected genes were investigated in post-mortem brain tissue from 30 AD patients and 30 age-matched controls in three interdependent brain areas of the PFC. Results were assessed in relation to Braak stage and cognitive impairment of the patients. We found a general age-related factor in Wnt pathway genes with a group of genes being closely interrelated in their expression across the time span investigated in healthy individuals. This interrelation was altered in the AD brains studied, as several genes presented aberrant transcription, even though not always being altered at protein levels. Noteworthy, beta(β)-catenin and glycogen synthase kinase 3-beta (GSK3β) showed a dynamic switch in protein levels and activity, especially in the orbitofrontal cortex and the medial frontal gyrus. A significant decrease in β-catenin protein levels were inversely associated with increased GSK3β tyrosine activating phosphorylation, in addition to downstream effects associated with disease progression and cognitive decline. This study is the first that comprehensively evaluates Wnt signaling pathway in the prefrontal cortical lobe structures of AD brains, in relation to age-related coordinated Wnt signaling changes. Our findings further support that increased kinase activity of GSK3β is associated with AD pathology in the PFC.

Targeting the Dvl-1/β-arrestin2/JNK3 interaction disrupts Wnt5a-JNK3 signaling and protects hippocampal CA1 neurons during cerebral ischemia reperfusion

It is well known that Wnt5a activation plays a pivotal role in brain injury and β-arrestin2 induces c-Jun N-terminal kinase (JNK3) activation is involved in neuronal cell death. Nonetheless, the relationship between Wnt5a and JNK3 remains unexplored during cerebral ischemia/reperfusion (I/R). In the present study, we tested the hypothesis that Wnt5a-mediated JNK3 activation via the Wnt5a-Dvl-1-β-arrestin2-JNK3 signaling pathway was correlated with I/R brain injury. We found that cerebral I/R could enhance the assembly of the Dvl-1-β-arrestin2-JNK3 signaling module, Dvl-1 phosphorylation and JNK3 activation. Activated JNK3 could phosphorylate the transcription factor c-Jun, prompt caspase-3 activation and ultimately lead to neuronal cell death. To further explore specifically Wnt5a mediated JNK3 pathway activation in neuronal injury, we used Foxy-5 (a peptide that mimics the effects of Wnt5a) and Box5 (a Wnt5a antagonist) both in vitro and in vivo. AS-β-arrestin2 (an antisense oligonucleotide against β-arrestin2) and RRSLHL (a small peptide that competes with β-arrestin2 for binding to JNK3) were applied to confirm the positive signal transduction effect of the Dvl-1-β-arrestin2-JNK3 signaling module during cerebral I/R. Furthermore, Box5 and the RRSLHL peptide were found to play protective roles in neuronal death both in vivo global and focal cerebral I/R rat models and in vitro oxygen glucose deprivation (OGD) neural cells. In summary, our results indicate that Wnt5a-mediated JNK3 activation participates in I/R brain injury by targeting the Dvl-1-β-arrestin2/JNK3 interaction. Our results also point to the possibility that disrupting Wnt5a-JNK3 signaling pathway may provide a new approach for stroke therapy.