Neuronal AChE splice variants and their non-hydrolytic functions: redefining a target of AChE inhibitors?

Reactive oxygen species signalling in the deterioration of quality of mammalian oocytes cultured in vitro: Protective effect of antioxidants

The in vitro fertilization (IVF) is the first choice of infertile couples worldwide to plan for conception. Besides having a significant advancement in IVF procedure, the success rate is still poor. Although several approaches have been tested to improve IVF protocol, minor changes in culture conditions, physical factors and/or drug treatment generate reactive oxygen species (ROS) in oocytes. Due to large size and huge number of mitochondria, oocyte is more susceptible towards ROS-mediated signalling under in vitro culture conditions. Elevation of ROS levels destabilize maturation promoting factor (MPF) that results in meiotic exit from diplotene as well as metaphase-II (M-II) arrest in vitro. Once meiotic exit occurs, these oocytes get further arrested at metaphase-I (M-I) stage or metaphase-III (M-III)-like stage under in vitro culture conditions. The M-I as well as M-III arrested oocytes are not fit for fertilization and limits IVF outcome. Further, the generation of excess levels of ROS cause oxidative stress (OS) that initiate downstream signalling to initiate various death pathways such as apoptosis, autophagy, necroptosis and deteriorates oocyte quality under in vitro culture conditions. The increase of cellular enzymatic antioxidants and/or supplementation of exogenous antioxidants in culture medium protect ROS-induced deterioration of oocyte quality in vitro. Although a growing body of evidence suggests the ROS and OS-mediated deterioration of oocyte quality in vitro, their downstream signalling and related mechanisms remain poorly understood. Hence, this review article summarizes the existing evidences concerning ROS and OS-mediated downstream signalling during deterioration of oocyte quality in vitro. The use of various antioxidants against ROS and OS-mediated impairment of oocyte quality in vitro has also been explored in order to increase the success rate of IVF during assisted reproductive health management.

Preliminary study of the consciousness-promotion mechanism of electroacupuncture in comatose patients with diffuse axonal injuries

BACKGROUND

Diffuse axonal injury (DAI) accounts for 30-40% of total neurotrauma cases, and the majority among them manifest with consciousness disturbance. At present, the understanding of the treatment of coma and awakening in patients with DAIs is still limited. This study is characterized by the use of electroacupuncture along with conventional Western medicine to promote consciousness more effectively in comatose patients with DAIs, shorten their time spent in a coma, and gain time for more favorable treatments during follow-up rehabilitation in order to improve the cure rate, reduce the morbidity rate, and achieve better therapeutic effects.

METHODS

In this randomized controlled study, 145 comatose patients with DAIs (type III) were divided into the treatment group (N.=71) and control group (N.=74). The patients in the control group were treated with conventional Western medicine, while those in the treatment group were treated with both electroacupuncture and conventional treatment. The Glasgow Coma Scale (GCS) scores and consciousness-promotion rates of both groups were observed before treatment as well as 10, 20, and 30 days after treatment. Meanwhile, serum acetylcholinesterase E (AchE) concentrations in both groups were measured with ELISA, while AchE activity was determined with the rate method. Correlations between GCS score, AchE concentration, and AchE activity in the treatment group were analyzed by using the stepwise multiple regression method.

RESULTS

The GCS scores in the treatment group showed significant increases after the first, second, and third courses of treatment when compared to the pre-treatment scores (P<0.05). After 1 course of treatment, the GCS scores in the control group were not statistically significantly different compared to the pre-treatment scores (P>0.05), whereas after 2 and 3 courses of treatment, the differences were of greater statistical significance (P<0.05). Statistically significant differences between the two groups were found in GCS scores in the same course of treatment (P<0.05). The consciousness-promotion rates between the two groups after the same treatment course were statistically significantly different (P<0.05). Both the standardized regression coefficients and partial correlation coefficients showed that AchE concentration had a certain influence on GCS score (|Beta|=0.3601; r Y2.1=0.726).

CONCLUSIONS

Conventional Western medicine combined with electroacupuncture treatment may promote the consciousness of patients with DAIs and shorten the amount of time they spend comatose. Furthermore, the neurotransmitter AchE may play a role in the pathophysiological mechanism of consciousness promotion.

Combined Donepezil with Astaxanthin via Nanostructured Lipid Carriers Effective Delivery to Brain for Alzheimer's Disease in Rat Model

Introduction

Donepezil (DPL), a specific acetylcholinesterase inhibitor, is used as a first-line treatment to improve cognitive deficits in Alzheimer's disease (AD) and it might have a disease modifying effect. Astaxanthin (AST) is a natural potent antioxidant with neuroprotective, anti-amyloidogenic, anti-apoptotic, and anti-inflammatory effects. This study aimed to prepare nanostructured lipid carriers (NLCs) co-loaded with donepezil and astaxanthin (DPL/AST-NLCs) and evaluate their in vivo efficacy in an AD-like rat model 30 days after daily intranasal administration.

Methods

DPL/AST-NLCs were prepared using a hot high-shear homogenization technique, in vitro examined for their physicochemical parameters and in vivo evaluated. AD induction in rats was performed by aluminum chloride. The cortex and hippocampus were isolated from the brain of rats for biochemical testing and histopathological examination.

Results

DPL/AST-NLCs showed z-average diameter 149.9 ± 3.21 nm, polydispersity index 0.224 ± 0.017, zeta potential -33.7 ± 4.71 mV, entrapment efficiency 81.25 ±1.98% (donepezil) and 93.85 ±1.75% (astaxanthin), in vitro sustained release of both donepezil and astaxanthin for 24 h, spherical morphology by transmission electron microscopy, and they were stable at 4-8 ± 2°C for six months. Differential scanning calorimetry revealed that donepezil and astaxanthin were molecularly dispersed in the NLC matrix in an amorphous state. The DPL/AST-NLC-treated rats showed significantly lower levels of nuclear factor-kappa B, malondialdehyde, β-site amyloid precursor protein cleaving enzyme-1, caspase-3, amyloid beta (Aβ1‑42), and acetylcholinesterase, and significantly higher levels of glutathione and acetylcholine in the cortex and hippocampus than the AD-like untreated rats and that treated with donepezil-NLCs. DPL/AST-NLCs showed significantly higher anti-amyloidogenic, antioxidant, anti-acetylcholinesterase, anti-inflammatory, and anti-apoptotic effects, resulting in significant improvement in the cortical and hippocampal histopathology.

Conclusion

Nose-to-brain delivery of DPL/AST-NLCs is a promising strategy for the management of AD.

The human acetylcholinesterase C-terminal T30 peptide activates neuronal growth through alpha 7 nicotinic acetylcholine receptors and the mTOR pathway

Acetylcholinesterase (AChE) is a highly conserved enzyme responsible for the regulation of acetylcholine signaling within the brain and periphery. AChE has also been shown to participate in non-enzymatic activity and contribute to cellular development and aging. In particular, enzymatic cleavage of the synaptic AChE isoform, AChE-T, is shown to generate a bioactive T30 peptide that binds to the ⍺7 nicotinic acetylcholine receptor (nAChR) at synapses. Here, we explore intracellular mechanisms of T30 signaling within the human cholinergic neural cell line SH-SY5Y using high performance liquid chromatography (HPLC) coupled to electrospray ionization mass spectrometry (ESI-MS/MS). Proteomic analysis of cells exposed to (100 nM) T30 for 3-days reveals significant changes within proteins important for cell growth. Specifically, bioinformatic analysis identifies proteins that converge onto the mammalian target of rapamycin (mTOR) pathway signaling. Functional experiments confirm that T30 regulates neural cell growth via mTOR signaling and ⍺7 nAChR activation. T30 was found promote mTORC1 pro-growth signaling through an increase in phosphorylated elF4E and S6K1, and a decrease in the autophagy LC3B-II protein. These findings are corroborated in hippocampal neurons and show that T30 promotes dendritic arborization. Taken together, our findings define mTOR as a novel pathway activated by T30 interaction with the nAChR and suggest a role for this process in human disease.

Beyond apoptosis: evidence of other regulated cell death pathways in the ovary throughout development and life

BACKGROUND

Regulated cell death is a fundamental component of numerous physiological processes; spanning from organogenesis in utero, to normal cell turnover during adulthood, as well as the elimination of infected or damaged cells throughout life. Quality control through regulation of cell death pathways is particularly important in the germline, which is responsible for the generation of offspring. Women are born with their entire supply of germ cells, housed in functional units known as follicles. Follicles contain an oocyte, as well as specialized somatic granulosa cells essential for oocyte survival. Follicle loss-via regulated cell death-occurs throughout follicle development and life, and can be accelerated following exposure to various environmental and lifestyle factors. It is thought that the elimination of damaged follicles is necessary to ensure that only the best quality oocytes are available for reproduction.

OBJECTIVE AND RATIONALE

Understanding the precise factors involved in triggering and executing follicle death is crucial to uncovering how follicle endowment is initially determined, as well as how follicle number is maintained throughout puberty, reproductive life, and ovarian ageing in women. Apoptosis is established as essential for ovarian homeostasis at all stages of development and life. However, involvement of other cell death pathways in the ovary is less established. This review aims to summarize the most recent literature on cell death regulators in the ovary, with a particular focus on non-apoptotic pathways and their functions throughout the discrete stages of ovarian development and reproductive life.

SEARCH METHODS

Comprehensive literature searches were carried out using PubMed and Google Scholar for human, animal, and cellular studies published until August 2022 using the following search terms: oogenesis, follicle formation, follicle atresia, oocyte loss, oocyte apoptosis, regulated cell death in the ovary, non-apoptotic cell death in the ovary, premature ovarian insufficiency, primordial follicles, oocyte quality control, granulosa cell death, autophagy in the ovary, autophagy in oocytes, necroptosis in the ovary, necroptosis in oocytes, pyroptosis in the ovary, pyroptosis in oocytes, parthanatos in the ovary, and parthanatos in oocytes.

OUTCOMES

Numerous regulated cell death pathways operate in mammalian cells, including apoptosis, autophagic cell death, necroptosis, and pyroptosis. However, our understanding of the distinct cell death mediators in each ovarian cell type and follicle class across the different stages of life remains the source of ongoing investigation. Here, we highlight recent evidence for the contribution of non-apoptotic pathways to ovarian development and function. In particular, we discuss the involvement of autophagy during follicle formation and the role of autophagic cell death, necroptosis, pyroptosis, and parthanatos during follicle atresia, particularly in response to physiological stressors (e.g. oxidative stress).

WIDER IMPLICATIONS

Improved knowledge of the roles of each regulated cell death pathway in the ovary is vital for understanding ovarian development, as well as maintenance of ovarian function throughout the lifespan. This information is pertinent not only to our understanding of endocrine health, reproductive health, and fertility in women but also to enable identification of novel fertility preservation targets.

Immunohistochemistry for acetylcholinesterase and butyrylcholinesterase in the dorsal motor nucleus of the vagus (DMNV) of formalin-fixed, paraffin-embedded tissue: comparison with reported literature

The majority of research regarding the expression of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in the brain has been conducted using histochemistry to identify enzymatic activity in frozen fixed tissue. However, retrospective human neurochemistry studies are generally restricted to formalin-fixed, paraffin-embedded (FFPE) tissues that are not suitable for histochemical procedures. The availability of commercially available antibody formulations provides the means to study such tissues by immunohistochemistry (IHC). In this study, we optimised IHC conditions for evaluating the expression of AChE and BuChE in the brainstem, focusing on the dorsal motor nucleus of the vagus, in human and piglet FFPE tissues, using commercially available antibodies. Our results were compared to published reports of histochemically determined AChE and BuChE expression. We varied antibody concentrations and antigen retrieval methods, and evaluated different detection systems, with the overall aim to optimise immunohistochemical staining. The primary findings, consistent across both species, are: (1) AChE and BuChE expression dominated in the neuronal somata, specifically in the neuronal cytoplasm; and (2) no change in the protocol resulted in axonal/neuropil expression of AChE. These results indicate that IHC is a suitable tool to detect AChE and BuChE in FFPE tissue using commercial antibodies, albeit the staining patterns obtained differed from those using histochemistry in frozen tissue. The underlying cause(s) for these differences are discussed in detail and may be associated with the principal components of the staining method, the antibody protein target and/or limitations to the detection of epitopes by tissue fixation.

Potential bioactive compounds and mechanisms of Fibraurea recisa Pierre for the treatment of Alzheimer's disease analyzed by network pharmacology and molecular docking prediction

Introduction

Heat-clearing and detoxifying Chinese medicines have been documented to have anti-Alzheimer's disease (AD) activities according to the accumulated clinical experience and pharmacological research results in recent decades. In this study, Fibraurea recisa Pierre (FRP), the classic type of Heat-clearing and detoxifying Chinese medicine, was selected as the object of research.

Methods

12 components with anti-AD activities were identified in FRP by a variety of methods, including silica gel column chromatography, multiple databases, and literature searches. Then, network pharmacology and molecular docking were adopted to systematically study the potential anti-AD mechanism of these compounds. Consequently, it was found that these 12 compounds could act on 235 anti-AD targets, of which AKT and other targets were the core targets. Meanwhile, among these 235 targets, 71 targets were identified to be significantly correlated with the pathology of amyloid beta (Aβ) and Tau.

Results and discussion

In view of the analysis results of the network of active ingredients and targets, it was observed that palmatine, berberine, and other alkaloids in FRP were the key active ingredients for the treatment of AD. Further, Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis revealed that the neuroactive ligand-receptor interaction pathway and PI3K-Akt signaling pathway were the most significant signaling pathways for FRP to play an anti-AD role. Findings in our study suggest that multiple primary active ingredients in FRP can play a multitarget anti-AD effect by regulating key physiological processes such as neurotransmitter transmission and anti-inflammation. Besides, key ingredients such as palmatine and berberine in FRP are expected to be excellent leading compounds of multitarget anti-AD drugs.

Activity-Based Protein Profiling of Human and Plasmodium Serine Hydrolases and Interrogation of Potential Antimalarial Targets

Malaria remains a global health issue requiring the identification of novel therapeutic targets to combat drug resistance. Metabolic serine hydrolases are druggable enzymes playing essential roles in lipid metabolism. However, very few have been investigated in malaria-causing parasites. Here, we used fluorophosphonate broad-spectrum activity-based probes and quantitative chemical proteomics to annotate and profile the activity of more than half of predicted serine hydrolases in P. falciparum across the erythrocytic cycle. Using conditional genetics, we demonstrate that the activities of four serine hydrolases, previously annotated as essential (or important) in genetic screens, are actually dispensable for parasite replication. Of importance, we also identified eight human serine hydrolases that are specifically activated at different developmental stages. Chemical inhibition of two of them blocks parasite replication. This strongly suggests that parasites co-opt the activity of host enzymes and that this opens a new drug development strategy against which the parasites are less likely to develop resistance.

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P. falciparum has 48 predicted metabolic SHs. Many react with the ABP, FP-N₃

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The activity of 25 PfSHs and 8 HsSHs was profiled throughout the asexual life cycle

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Catalytic mutants of 4 PfSHs (formerly held essential) had no parasite growth effect

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Selective inhibitors for 2 HsSHs (APEH and LPLA2) affected parasite growth

Bisphenol A single and repeated treatment increases HDAC2, leading to cholinergic neurotransmission dysfunction and SN56 cholinergic apoptotic cell death through AChE variants overexpression and NGF/TrkA/P75NTR signaling disruption

Bisphenol-A (BPA), a widely used plasticizer, induces cognitive dysfunctions following single and repeated exposure. Several studies, developed in hippocampus and cortex, tried to find the mechanisms that trigger and mediate these dysfunctions, but those are still not well known. Basal forebrain cholinergic neurons (BFCN) innervate hippocampus and cortex, regulating cognitive function, and their loss or the induction of cholinergic neurotransmission dysfunction leads to cognitive disabilities. However, no studies were performed in BFCN. We treated wild type or histone deacetylase (HDAC2), P75^NTR or acetylcholinesterase (AChE) silenced SN56 cholinergic cells from BF with BPA (0.001 μM-100 μM) with or without recombinant nerve growth factor (NGF) and with or without acetylcholine (ACh) for one- and fourteen days in order to elucidate the mechanisms underlying these effects. BPA induced cholinergic neurotransmission disruption through reduction of ChAT activity, and produced apoptotic cell death, mediated partially through AChE-S overexpression and NGF/TrkA/P75^NTR signaling dysfunction, independently of cholinergic neurotransmission disruption, following one- and fourteen days of treatment. BPA mediates these alterations, in part, through HDAC2 overexpression. These data are relevant since they may help to elucidate the neurotoxic mechanisms that trigger the cognitive disabilities induced by BPA exposure, providing a new therapeutic approach.

Strategic approaches to target the enzymes using natural compounds for the management of Alzheimer's disease: A review

Alzheimer's disease (AD) is a chronic neurodegenerative disease. It is clinically characterized by memory loss and intellectual decrease, among other neurological deficits. The etiology of AD is not completely understood but includes amyloid plaques and intracellular helical filaments as well as neurofibrillary tangles with hyperphosphorylated tau protein. AD is also associated with alterations in amyloid processing genes, such as PSEN1 or PSEN2 and APP. The modulation immune system, cholesterol metabolism, and synaptic vesicle endocytosis have all been shown to remediate AD. In this review, enzymes such as AChE, BuChE, β-secretase, γ-secretase, MAO, and RAGE are discussed as potential targets for AD treatment. The aim of this review was to addresses the molecular mechanisms as well as various genetic factors in AD etiology. The use of natural compounds against these targets might be beneficial for the management of AD.

Significant effects of cholinesterase inhibitors on tau pathology in the Alzheimer's disease continuum: An in vivo positron emission tomography study

OBJECTIVES

No prior study has assessed the effects of cholinesterase inhibitors (ChEIs) on tau pathology in the brains of patients with Alzheimer's disease (AD). Using positron emission tomography, this study aimed to investigate whether ChEIs reduce tau aggregation in amyloid-positive participants.

METHODS

We analyzed datasets from the Alzheimer's Disease Neuroimaging Initiative and included amyloid-positive participants who had undergone baseline and 1- or 2-year follow-up AV-1451 positron emission tomography scans. We included participants treated with and without ChEIs (ChEIs group: n = 15, No-ChEIs group, n = 45). The annual change in tau aggregation was calculated as the difference in AV-1451- standardized uptake value ratio (SUVR) between the two scans divided by the time between scans. Group differences in annual AV-1451-SUVR change were examined.

RESULTS

We found a significantly lower annual change in AV-1451-SUVR in the Braak 1/2 regions (entorhinal cortex and hippocampus) of participants taking ChEIs. Increased AV-1451-SUVR between the first and second examinations were observed in 22 of 45 participants not taking ChEIs and 2 of 15 participants taking ChEIs. Fisher's exact test showed a significant difference in the ratio of participants with increased AV-1451-SUVR between the groups.

CONCLUSIONS

The findings of this positron emission tomography study suggest that the administration of ChEIs has some neuroprotective effects in patients of the AD continuum, at least in the early stage of the disease progression. This in vivo effect may be mediated via tau, preventing amyloid β-induced neurotoxicity.

Timing and localization of myasthenia gravis-related gene expression

Myasthenia gravis (MG) is an acquired autoimmune disorder caused by autoantibodies binding acetylcholine receptors (AChR), muscle‐specific kinase (MuSK), agrin or low‐density lipoprotein receptor‐related protein 4 (Lrp4). These autoantibodies inhibit neuromuscular transmission by blocking the function of these proteins and thereby cause fluctuating skeletal muscle weakness. Several reports suggest that these autoantibodies might also affect the central nervous system (CNS) in MG patients. A comprehensive overview of the timing and localization of the expression of MG‐related antigens in other organs is currently lacking. To investigate the spatio‐temporal expression of MG‐related genes outside skeletal muscle, we used in silico tools to assess public expression databases. Acetylcholine esterase, nicotinic AChR α1 subunit, agrin, collagen Q, downstream of kinase‐7, Lrp4, MuSK and rapsyn were included as MG‐related genes because of their well‐known involvement in either congenital or autoimmune MG. We investigated expression of MG‐related genes in (1) all human tissues using GTEx data, (2) specific brain regions, (3) neurodevelopmental stages, and (4) cell types using datasets from the Allen Institute for Brain Sciences. MG‐related genes show heterogenous spatio‐temporal expression patterns in the human body as well as in the CNS. For each of these genes, several (new) tissues, brain areas and cortical cell types with (relatively) high expression were identified suggesting a potential role for these genes outside skeletal muscle. The possible presence of MG‐related antigens outside skeletal muscle suggests that autoimmune MG, congenital MG or treatments targeting the same proteins may affect MG‐related protein function in other organs.

Acetylcholinesterase and human cancers

The enzyme acetylcholinesterase (AChE) is a serine hydrolase whose primary function is to degrade acetylcholine (ACh) and terminate neurotransmission. Apart from its role in synaptic transmission, AChE has several "non-classical" functions in non-neuronal cells. AChE is involved in cellular growth, apoptosis, drug resistance pathways, response to stress signals and inflammation. The observation that the functional activity of AChE is altered in human tumors (relative to adjacent matched normal tissue) has raised several intriguing questions about its role in the pathophysiology of human cancers. Published reports show that AChE is a vital regulator of oncogenic signaling pathways involving proliferation, differentiation, cell-cell adhesion, migration, invasion and metastasis of primary tumors. The objective of this book chapter is to provide a comprehensive overview of the contributions of the AChE-signaling pathway in the growth of progression of human cancers. The AChE isoforms, AChE-T, AChE-R and AChE-S are robustly expressed in human cancer cell lines as well in human tumors (isolated from patients). Traditionally, AChE-modulators have been used in the clinic for treatment of neurodegenerative disorders. Emerging studies reveal that these drugs could be repurposed for the treatment of human cancers. The discovery of potent, selective AChE ligands will provide new knowledge about AChE-regulatory pathways in human cancers and foster the hope of novel therapies for this disease.

Bradycardia Due to Donepezil in Adults: Systematic Analysis of FDA Adverse Event Reporting System

Background: Bradycardia is a physiological condition characterized by a decrease in heart rate and is a side effect of many drug classes. Bradycardia has been reported as an adverse event for patients receiving donepezil for Alzheimer’s disease (AD) treatment. Objective: The purpose of the paper is to systematically investigate the association between the occurrence of bradycardia in adults and the usage of donepezil using clinical data derived from the FDA Adverse Event Reporting System (FAERS) database. Methods: The risk of bradycardia in patients who only took donepezil was compared with those of patients who only took over-the-counter medications, multiple arrhythmia drugs, or other medications for AD treatment. In addition, this study sought to determine if this heightened bradycardia risk was influenced by sex, age, and dosage. Results: The results indicated that there was a significant greater likelihood of reporting bradycardia in patients administered donepezil than most of the drugs investigated. There was no significant association between age or the dosage of donepezil and the likelihood of reporting bradycardia. However, males were found to be more likely than females to report bradycardia as an adverse event. Tumor necrosis factor inhibition and the stimulation of endothelial nitric oxide synthase were proposed to be the primary mechanism of actions which confer elevated bradycardia risk when using donepezil. Conclusion: These findings identified strong association between the usage of donepezil and bradycardia in adults as well as provided insight into the underlying molecular mechanisms that induce bradycardia by donepezil.

Characterization of the rat Acetylcholinesterase readthrough (AChE-R) splice variant: Implications for toxicological studies

Exposure to chemicals and other environmental stressors can differentially impact the expression of Acetylcholinesterase (AChE) splice variants. Surprisingly, despite the widespread use of the rat model in toxicological studies and the wealth of literature on this important biomarker of neurotoxicity, AChE coding exons and splice variants are not yet fully annotated in this species. To address this knowledge gap, a short problematic region of the rat AChE genomic DNA present in GenBank was first re-sequenced. This revised genomic sequence was then aligned to rat AChE RefSeq mRNA and compared to orthologous mammalian sequences, in order to map the coding exon and intron boundaries of the rat AChE gene. Based on these bioinformatics analyses, a sequence was predicted for the yet-unannotated rat Acetylcholinesterase readthrough (AChE-R) splice variant. PCR primers designed to specifically amplify rat AChE-R were used to confirm its expression in rat PC12 cells. Compared to the canonical AChE-S splice variant, AChE-R was expressed at much lower levels but presented distinct regulation patterns in PC12 cells and rat primary cerebral granule cells (CGCs) following exposure to Chlorpyrifos (a well-known neurotoxic organophosphate pesticide). Taken together, these observations point to the evolutionary conservation of the AChE-R splicing event between rodents and human and to the distinct regulation of AChE splice variants in response to toxicological challenges.

Reconsideration of Anticholinesterase Therapeutic Strategies against Alzheimer's Disease

Alzheimer's disease (AD) is well-known as a severe neurodegeneration disease involving complicated etiologies, and cholinesterase inhibition remain the prevailing mode of clinical intervention in AD management. Although most clinically applied cholinesterase inhibitors (ChEIs) achieve limited clinical outcomes, research on the central cholinergic system is still thriving. Recently, an impressive amount of knowledge regarding novel acetylcholinesterase functions, as well as the close association between the central cholinergic system and other key elements for AD pathogenesis, has accumulated, highlighting that this field still has great potential for future drug development. In contrast to the overwhelmingly disappointing clinical therapeutic effects of various disease-modifying drug candidates, interesting evidence has continued to emerge over the past 20 years from the wealth of preclinical and clinical data on the usage of ChEIs, indicating underestimated clinical benefits due to physician ambivalence, a lack of persistent treatment, and inappropriate medication times or doses. Here we pinpoint several topics fit for future attention, focusing on the updated cholinergic hypothesis, especially the pleiotropic relationships with key pathogenetic signaling pathways and functions in AD, as well as possible novel therapeutic strategies, including novel ChEIs and cholinesterase inhibition-based innovative multifunctional therapeutic candidates. We intend to strengthen the future value of the precise application of cholinergic drugs, especially novel ChEIs, as a cornerstone pharmacological approach to AD treatment, either alone or in combination with other targets, to relieve symptoms and to modify disease progression.

Manganese induced ROS and AChE variants alteration leads to SN56 basal forebrain cholinergic neuronal loss after acute and long-term treatment

Manganese (Mn) induces cognitive disorders and basal forebrain (BF) cholinergic neuronal loss, involved on learning and memory regulation, which could be the cause of such cognitive disorders. However, the mechanisms through which it induces these effects are unknown. We hypothesized that Mn could induce BF cholinergic neuronal loss through oxidative stress generation, cholinergic transmission and AChE variants alteration that could explain Mn cognitive disorders. This study shows that Mn impaired cholinergic transmission in SN56 cholinergic neurons from BF through alteration of AChE and ChAT activity and CHT expression. Moreover, Mn induces, after acute and long-term exposure, AChE variants alteration and oxidative stress generation that leaded to lipid peroxidation and protein oxidation. Finally, Mn induces cell death on SN56 cholinergic neurons and this effect is independent of cholinergic transmission alteration, but was mediated partially by oxidative stress generation and AChE variants alteration. Our results provide new understanding of the mechanisms contributing to the harmful effects of Mn on cholinergic neurons and their possible involvement in cognitive disorders induced by Mn.

Necroptosis in stressed ovary

Stress is deeply rooted in the modern society due to limited resources and large competition to achieve the desired goal. Women are more frequently exposed to several stressors during their reproductive age that trigger generation of reactive oxygen species (ROS). Accumulation of ROS in the body causes oxidative stress (OS) and adversely affects ovarian functions. The increased OS triggers various cell death pathways in the ovary. Beside apoptosis and autophagy, OS trigger necroptosis in granulosa cell as well as in follicular oocyte. The OS could activate receptor interacting protein kinase-1(RIPK1), receptor interacting protein kinase-3 (RIPK3) and mixed lineage kinase domain-like protein (MLKL) to trigger necroptosis in mammalian ovary. The granulosa cell necroptosis may deprive follicular oocyte from nutrients, growth factors and survival factors. Under these conditions, oocyte becomes more susceptible towards OS-mediated necroptosis in the follicular oocytes. Induction of necroptosis in encircling granulosa cell and oocyte may lead to follicular atresia. Indeed, follicular atresia is one of the major events responsible for the elimination of majority of germ cells from cohort of ovary. Thus, the inhibition of necroptosis could prevent precautious germ cell depletion from ovary that may cause reproductive senescence and early menopause in several mammalian species including human.

Identification of the neurotransmitter profile of AmFoxP expressing neurons in the honeybee brain using double-label in situ hybridization

BACKGROUND

FoxP transcription factors play crucial roles for the development and function of vertebrate brains. In humans the neurally expressed FOXPs, FOXP1, FOXP2, and FOXP4 are implicated in cognition, including language. Neural FoxP expression is specific to particular brain regions but FoxP1, FoxP2 and FoxP4 are not limited to a particular neuron or neurotransmitter type. Motor- or sensory activity can regulate FoxP2 expression, e.g. in the striatal nucleus Area X of songbirds and in the auditory thalamus of mice. The DNA-binding domain of FoxP proteins is highly conserved within metazoa, raising the possibility that cellular functions were preserved across deep evolutionary time. We have previously shown in bee brains that FoxP is expressed in eleven specific neuron populations, seven tightly packed clusters and four loosely arranged groups.

RESULTS

The present study examined the co-expression of honeybee FoxP (AmFoxP) with markers for glutamatergic, GABAergic, cholinergic and monoaminergic transmission. We found that AmFoxP could co-occur with any one of those markers. Interestingly, AmFoxP clusters and AmFoxP groups differed with respect to homogeneity of marker co-expression; within a cluster, all neurons co-expressed the same neurotransmitter marker, within a group co-expression varied. We also assessed qualitatively whether age or housing conditions providing different sensory and motor experiences affected the AmFoxP neuron populations, but found no differences.

CONCLUSIONS

Based on the neurotransmitter homogeneity we conclude that AmFoxP neurons within the clusters might have a common projection and function whereas the AmFoxP groups are more diverse and could be further sub-divided. The obtained information about the neurotransmitters co-expressed in the AmFoxP neuron populations facilitated the search of similar neurons described in the literature. These comparisons revealed e.g. a possible function of AmFoxP neurons in the central complex. Our findings provide opportunities to focus future functional studies on invertebrate FoxP expressing neurons. In a broader context, our data will contribute to the ongoing efforts to discern in which cases relationships between molecular and phenotypic signatures are linked evolutionary.

Necrosis and necroptosis in germ cell depletion from mammalian ovary

The maximum number of germ cells is present during the fetal life in mammals. Follicular atresia results in rapid depletion of germ cells from the cohort of the ovary. At the time of puberty, only a few hundred (<1%) germ cells are either culminated into oocytes or further get eliminated during the reproductive life. Although apoptosis plays a major role, necrosis as well as necroptosis, might also be involved in germ cell elimination from the mammalian ovary. Both necrosis and necroptosis show similar morphological features and are characterized by an increase in cell volume, cell membrane permeabilization, and rupture that lead to cellular demise. Necroptosis is initiated by tumor necrosis factor and operated through receptor interacting protein kinase as well as mixed lineage kinase domain-like protein. The acetylcholinesterase, cytokines, starvation, and oxidative stress play important roles in necroptosis-mediated granulosa cell death. The granulosa cell necroptosis directly or indirectly induces susceptibility toward necroptotic or apoptotic cell death in oocytes. Indeed, prevention of necrosis and necroptosis pathways using their specific inhibitors could enhance growth/differentiation factor-9 expression, improve survivability as well as the meiotic competency of oocytes, and prevent decline of reproductive potential in several mammalian species and early onset of menopause in women. This study updates the information and focuses on the possible involvement of necrosis and necroptosis in germ cell depletion from the mammalian ovary.

Acetylcholine signaling system in progression of lung cancers

The neurotransmitter acetylcholine (ACh) acts as an autocrine growth factor for human lung cancer. Several lines of evidence show that lung cancer cells express all of the proteins required for the uptake of choline (choline transporter 1, choline transporter-like proteins) synthesis of ACh (choline acetyltransferase, carnitine acetyltransferase), transport of ACh (vesicular acetylcholine transport, OCTs, OCTNs) and degradation of ACh (acetylcholinesterase, butyrylcholinesterase). The released ACh binds back to nicotinic (nAChRs) and muscarinic receptors on lung cancer cells to accelerate their proliferation, migration and invasion. Out of all components of the cholinergic pathway, the nAChR-signaling has been studied the most intensely. The reason for this trend is due to genome-wide data studies showing that nicotinic receptor subtypes are involved in lung cancer risk, the relationship between cigarette smoke and lung cancer risk as well as the rising popularity of electronic cigarettes considered by many as a "safe" alternative to smoking. There are a small number of articles which review the contribution of the other cholinergic proteins in the pathophysiology of lung cancer. The primary objective of this review article is to discuss the function of the acetylcholine-signaling proteins in the progression of lung cancer. The investigation of the role of cholinergic network in lung cancer will pave the way to novel molecular targets and drugs in this lethal malignancy.

Neuropeptide and steroid hormone mediators of neuroendocrine regulation

To maintain the health and well-being of all mammals, numerous aspects of physiology are controlled by neuroendocrine mechanisms. These mechanisms ultimately enable communication between neurones and glands throughout the body and are centrally mediated by neuropeptides and/or steroid hormones. A recent session at the International Workshop in Neuroendocrinology highlighted the essential roles of some of these neuropeptide and steroid hormone mediators in the neuroendocrine regulation of stress-, reproduction- and behaviour-related processes. Accordingly, the present review highlights topics presented in this session, including the role of the neuropeptides corticotrophin-releasing factor and gonadotrophin-releasing hormone in stress and reproductive physiology, respectively. Additionally, it details an important role for gonadal sex steroids in the development of behavioural sex preference.

Modulatory Effects of a Novel Cyclized Peptide in Reducing the Expression of Markers Linked to Alzheimer's Disease

Despite many studies attempt to identify the primary mechanisms underlying neurodegeneration in Alzheimer's disease (AD), the key events still remain elusive. We have previously shown that a peptide cleaved from the acetylcholinesterase (AChE) C-terminus (T14) can play a pivotal role as a signaling molecule in neurodegeneration, via its interaction with the α7 nicotinic acetylcholine receptor. The main goal of this study is to determine whether a cyclized variant (NBP14) of the toxic AChE-derived peptide can antagonize the effects of its linear counterpart, T14, in modulating well-known markers linked to neurodegeneration. We investigate this hypothesis applying NBP14 on ex-vivo rat brain slices containing the basal forebrain. Western blot analysis revealed an inhibitory action of NBP14 on naturally occurring T14 peptide, as well as on endogenous amyloid beta, whereas the expression of the nicotinic receptor and phosphorylated Tau was relatively unaffected. These results further confirm the neurotoxic properties of the AChE-peptide and show for the first time in an ex-vivo preparation the possible neuroprotective activity of NBP14, over a protracted period of hours, indicating that T14 pathway may offer a new prospect for therapeutic intervention in AD pathobiology.

Acetylcholine and necroptosis are players in follicular development in primates

Acetylcholine (ACh) in the ovary and its actions were linked to survival of human granulosa cells in vitro and improved fertility of rats in vivo. These effects were observed upon experimental blockage of the ACh-degrading enzyme (ACH esterase; ACHE), by Huperzine A. We now studied actions of Huperzine A in a three-dimensional culture of macaque follicles. Because a form of programmed necrotic cell death, necroptosis, was previously identified in human granulosa cells in vitro, we also studied actions of necrostatin-1 (necroptosis inhibitor). Blocking the breakdown of ACh by inhibiting ACHE, or interfering with necroptosis, did not improve the overall follicle survival, but promoted the growth of macaque follicles from the secondary to the small antral stage in vitro, which was correlated with oocyte development. The results from this translational model imply that ovarian function and fertility in primates may be improved by pharmacological interference with ACHE actions and necroptosis.

A second wind for the cholinergic system in Alzheimer's therapy

Notwithstanding tremendous research efforts, the cause of Alzheimer's disease (AD) remains elusive and there is no curative treatment. The cholinergic hypothesis presented 35 years ago was the first major evidence-based hypothesis on the etiology of AD. It proposed that the depletion of brain acetylcholine was a primary cause of cognitive decline in advanced age and AD. It relied on a series of observations obtained in aged animals, elderly, and AD patients that pointed to dysfunctions of cholinergic basal forebrain, similarities between cognitive impairments induced by anticholinergic drugs and those found in advanced age and AD, and beneficial effects of drugs stimulating cholinergic activity. This review revisits these major results to show how this hypothesis provided the drive for the development of anticholinesterase inhibitor-based therapies of AD, the almost exclusively approved treatment in use despite transient and modest efficacy. New ideas for improving cholinergic therapies are also compared and discussed in light of the current revival of the cholinergic hypothesis on the basis of two sets of evidence from new animal models and refined imagery techniques in humans. First, human and animal studies agree in detecting signs of cholinergic dysfunctions much earlier than initially believed. Second, alterations of the cholinergic system are deeply intertwined with its reactive responses, providing the brain with efficient compensatory mechanisms to delay the conversion into AD. Active research in this field should provide new insight into development of multitherapies incorporating cholinergic manipulation, as well as early biomarkers of AD enabling earlier diagnostics. This is of prime importance to counteract a disease that is now recognized to start early in adult life.

Beyond symptomatic effects: potential of donepezil as a neuroprotective agent and disease modifier in Alzheimer's disease

Alzheimer's disease (AD) is associated with neurodegenerative changes resulting clinically in progressive cognitive and functional deficits. The only therapies are the cholinesterase inhibitors donepezil, galantamine and rivastigmine and the N-methyl-D-aspartate-receptor antagonist memantine. Donepezil acts primarily on the cholinergic system as a symptomatic treatment, but it also has potential for disease modification and may reduce the rate of progression of AD. This review explores the potential for disease modifying effects of donepezil. Several neuroprotective mechanisms that are independent of cholinesterase inhibition, are suggested. Donepezil has demonstrated a range of effects, including protecting against amyloid β, ischaemia and glutamate toxicity; slowing of progression of hippocampal atrophy; and up-regulation of nicotinic acetylcholine receptors. Clinically, early and continuous treatment with donepezil is considered to preserve cognitive function more effectively than delayed treatment. The possible neuroprotective effects of donepezil and the potential for disease pathway modification highlight the importance of early diagnosis and treatment initiation in AD.

Primary hippocampal neuronal cell death induction after acute and repeated paraquat exposures mediated by AChE variants alteration and cholinergic and glutamatergic transmission disruption

Paraquat (PQ) is a widely used non-selective contact herbicide shown to produce memory and learning deficits after acute and repeated exposure similar to those induced in Alzheimer's disease (AD). However, the complete mechanisms through which it induces these effects are unknown. On the other hand, cholinergic and glutamatergic systems, mainly in the hippocampus, are involved on learning, memory and cell viability regulation. An alteration of hippocampal cholinergic or glutamatergic transmissions or neuronal cell loss may induce these effects. In this regard, it has been suggested that PQ may induce cell death and affect cholinergic and glutamatergic transmission, which alteration could produce neuronal loss. According to these data, we hypothesized that PQ could induce hippocampal neuronal loss through cholinergic and glutamatergic transmissions alteration. To prove this hypothesis, we evaluated in hippocampal primary cell culture, the PQ toxic effects after 24h and 14 consecutive days exposure on neuronal viability and the cholinergic and glutamatergic mechanisms related to it. This study shows that PQ impaired acetylcholine levels and induced AChE inhibition and increased CHT expression only after 14days exposure, which suggests that acetylcholine levels alteration could be mediated by these actions. PQ also disrupted glutamate levels through induction of glutaminase activity. In addition, PQ induced, after 24h and 14days exposure, cell death on hippocampal neurons that was partially mediated by AChE variants alteration and cholinergic and gultamatergic transmissions disruption. Our present results provide new view of the mechanisms contributing to PQ neurotoxicity and may explain cognitive dysfunctions observed after PQ exposure.

Ethyl Acetate Extract Components of Bushen-Yizhi Formula Provides Neuroprotection against Scopolamine-induced Cognitive Impairment

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder and there is no effective cure for this devastating disease to date. Bushen Yizhi Formula (BSYZ-F), a Chinese herbal compound, has proved to be effective for AD. In this study, we further investigate the effective part of BSYZ-F, ethyl acetate extract components of BSYZ-F (BSYZ-E), protects scopolamine (SCOP)-induced cognitive impairment, which shows a similar effect to BSYZ-F. We also find that BSYZ-E could protect against SCOP-induced cholinergic system dysfunction. In neuron function level, BSYZ-E remarkably elevates protein levels of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). BSYZ-E also significantly mitigates SCOP-induced apoptosis, oxidative stress and nitrosative stress. Conclusively, BSYZ-E, the effective part of BSYZ-F, can provide neuroprotection against SCOP-induced cognitive impairment through a multifunctional strategy. These findings suggest that BSYZ-E might be developed as a therapeutic drug for AD by targeting multiple pathways of the pathogenesis.

From dual binding site acetylcholinesterase inhibitors to allosteric modulators: A new avenue for disease-modifying drugs in Alzheimer's disease

The lack of an effective treatment for Alzheimer' disease (AD), an increasing prevalence and severe neurodegenerative pathology boost medicinal chemists to look for new drugs. Currently, only acethylcholinesterase (AChE) inhibitors and glutamate antagonist have been approved to the palliative treatment of AD. Although they have a short-term symptomatic benefits, their clinical use have revealed important non-cholinergic functions for AChE such its chaperone role in beta-amyloid toxicity. We propose here the design, synthesis and evaluation of non-toxic dual binding site AChEIs by hybridization of indanone and quinoline heterocyclic scaffolds. Unexpectely, we have found a potent allosteric modulator of AChE able to target cholinergic and non-cholinergic functions by fixing a specific AChE conformation, confirmed by STD-NMR and molecular modeling studies. Furthermore the promising biological data obtained on human neuroblastoma SH-SY5Y cell assays for the new allosteric hybrid 14, led us to propose it as a valuable pharmacological tool for the study of non-cholinergic functions of AChE, and as a new important lead for novel disease modifying agents against AD.

Brain region-specific effects of immobilization stress on cholinesterases in mice

Brain acetylcholinesterase (AChE) variant AChE_R expression increases with acute stress, and this persists for an extended period, although the timing, strain and laterality differences, have not been explored previously. Acute stress transiently increases acetylcholine release, which in turn may increase activity of cholinesterases. Also the AChE gene contains a glucocorticoid response element (GRE), and stress-inducible AChE transcription and activity changes are linked to increased glucocorticoid levels. Corticotropin-releasing hormone knockout (CRH-KO) mice have basal glucocorticoid levels similar to wild type (WT) mice, but much lower levels during stress. Hence we hypothesized that CRH is important for the cholinesterase stress responses, including butyrylcholinesterase (BChE). We used immobilization stress, acute (30 or 120 min) and repeated (120 min daily × 7) in 48 male mice (24 WT and 24 CRH-KO) and determined AChE_R, AChE and BChE mRNA expression and AChE and BChE activities in left and right brain areas (as cholinergic signaling shows laterality). Immobilization decreased BChE mRNA expression (right amygdala, to 0.5, 0.3 and 0.4, × control respectively) and AChE_R mRNA expression (to 0.5, 0.4 and 0.4, × control respectively). AChE mRNA expression increased (1.3, 1.4 and 1.8-fold, respectively) in the left striatum (Str). The AChE activity increased in left Str (after 30 min, 1.2-fold), decreased in right parietal cortex with repeated stress (to 0.5 × control). BChE activity decreased after 30 min in the right CA3 region (to 0.4 × control) but increased (3.8-fold) after 120 min in the left CA3 region. The pattern of changes in CRH-KO differed from that in WT mice.

AChE Inhibition-based Multi-target-directed Ligands, a Novel Pharmacological Approach for the Symptomatic and Disease-modifying Therapy of Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia in elder people, characterised by a progressive decline in memory as a result of an impairment of cholinergic neurotransmission. To date acetylcholinesterase inhibitors (AChEIs) have become the most prescribed drugs for the symptomatic treatment of mild to moderate AD. However, the traditional “one molecule-one target” paradigm is not sufficient and appropriate to yield the desired therapeutic efficacy since multiple factors, such as amyloid-β (Aβ) deposits, neuroinflammation, oxidative stress, and decreased levels of acetylcholine (ACh) have been thought to play significant roles in the AD pathogenesis. New generation of multi-target drugs is earnestly demanded not only for ameliorating symptoms but also for modifying the disease. Herein, we delineated the catalytic and non-catalytic functions of AChE, and summarized the works of our group and others in research and development of novel AChEI-based multi-target-directed ligands (MTDLs), such as dual binding site AChEIs and multi-target AChEIs inhibiting Aβ aggregation, regulating Aβ procession, antagonizing platelet-activating factor (PAF) receptor, scavenging oxygen radical, chelating metal ions, inhibiting monoamine oxidase B (MAO-B), blocking N-methyl-D-aspartic acid (NMDA) receptor and others.

Primary Investigation for the Mechanism of Biatractylolide from Atractylodis Macrocephalae Rhizoma as an Acetylcholinesterase Inhibitor

Biatractylolide was isolated from ethyl acetate extract of dried Atractylodis Macrocephalae Rhizoma root by multistep chromatographic processing. Structure of biatractylolide was confirmed by (1)H-NMR and (13)C-NMR. The IC50 on acetylcholinesterase (AChE) activity was 6.5458 μg/mL when the control IC50 value of huperzine A was 0.0192 μg/mL. Molecular Docking Software (MOE) was used to discover molecular sites of action between biatractylolide and AChE protein by regular molecular docking approaches. Moreover, biatractylolide downregulated the expression of AChE of MEF and 293T cells in a dose-dependent manner. These results demonstrated that the molecular mechanisms of inhibitory activities of biatractylolide on AChE are not only through binding to AChE, but also via reducing AChE expression by inhibiting the activity of GSK3β.

Age-dependent modulation of fasting and long-term dietary restriction on acetylcholinesterase in non-neuronal tissues of mice

Dietary restriction (DR) without malnutrition is a robust intervention that extends lifespan and slows the onset of nervous system deficit and age-related diseases in diverse organisms. Acetylcholinesterase (AChE), a thoroughly studied enzyme better known for hydrolyzing acetylcholine (ACh) in neuronal tissues, has recently been linked with multiple unrelated biological functions in different non-neuronal tissues. In the present study, the activity and protein expression level of AChE in liver, heart, and kidney of young (1 month), adult (6 month), and aged (18 month) mice were investigated. We also studied age- and tissue-specific changes in AChE activity and protein expression level after the mice were subjected to 24-h fasting and long-term DR. Our results showed that AChE activity and protein expression in kidney and heart of aged mice decreased significantly in comparison with young mice. On the contrary, long-term DR decreases the AChE activity and the protein expression level in all tissues irrespective of ages studied. We summarized that changes in AChE with age in different tissues studied reflects its different roles at different phases of an organism's life. Conversely, the cumulative modulation manifested in the form of lowering AChE by long-term DR may prevent the futile synthesis and accumulation of unwanted AChE besides the added compensatory benefit of enhanced ACh availability needed during the period of starvation. This, in turn, may help in preventing the declining homeostatic roles of this important neurotransmitter in different tissues.

MRNA Levels of ACh-Related Enzymes in the Hippocampus of THY-Tau22 Mouse: A Model of Human Tauopathy with No Signs of Motor Disturbance

The microtubule-associated protein Tau tends to form aggregates in neurodegenerative disorders referred to as tauopathies. The tauopathy model transgenic (Tg) THY-Tau22 (Tau22) mouse shows disturbed septo-hippocampal transmission, memory deficits and no signs of motor dysfunction. The reports showing a hippocampal downregulation of choline acetyltransferase (ChAT) in SAMP8 mice, a model of aging, and an upregulation of acetylcholinesterase (AChE) in Tg-VLW mice, a model of FTDP17 tauopathy, may lead to think that the supply of ACh to the hippocampus can be threatened as aging or Tau pathology progress. The above was tested by comparing the mRNA levels for ACh-related enzymes in hippocampi of wild-type (wt) and Tau22 mice at ages when the neuropathological signs are debuting (3-4 months), moderate (6-7 months) and extensive (>9 months). Age-matched Tau22 and wt mice hippocampi displayed similar ChAT, AChE-T, butyrylcholinesterase (BChE) and a proline-rich membrane anchor (PRiMA) mRNA levels, any change most likely arising from ACh homeostasis. The unchanged hippocampal levels of AChE-T mRNA and enzyme activity observed in Tau22 mice, expressing G272V-P301S hTau, differed from the increase in AChE-T mRNA and activity observed in Tg-VLW mice, expressing G272V-P301L-R406W hTau. The difference supports the idea that AChE upregulation may proceed or not depending on the particular Tau mutation, which would dictate Tau folding, the accessibility/affinity to kinases and phosphatases, and P-Tau aggregation with itself and protein partners, transcription factors included.

Donepezil prevents RANK-induced bone loss via inhibition of osteoclast differentiation by downregulating acetylcholinesterase

Objective

Donepezil, an inhibitor of acetylcholinesterase (AChE) targeting the brain, is a common medication for Alzheimer's disease. Interestingly, a recent clinical study found that administration of this agent is associated with lower risk of hip fracture independently of falling, suggesting its direct effect on bone tissues as well. AChE has been reported to be involved in osteoblast function, but the role of AChE on osteoclastogenesis still remains unclear. We analyzed the effect of AChE and donepezil on osteoclastogenesis in vivo and in vitro.

Methods

Cell-based assays were conducted using osteoclasts generated in cultures of murine bone marrow macrophages (BMMs) with receptor activator of nuclear factor-kappa B ligand (RANKL). The effect of donepezil was also determined in vivo using a mouse model of RANKL-induced bone loss.

Results

Recombinant AChE in BMMs cultured with RANKL further promoted RANKL-induced tartrate-resistant acid phosphatase (TRAP)-positive osteoclast differentiation. RANKL also upregulated AChE expression in BMMs. RNA interference-mediated knockdown of AChE significantly inhibited RANKL-induced osteoclast differentiation and suppressed gene expression specific for osteoclasts. AChE upregulated expression of RANK, the receptor of RANKL, in BMMs. Donepezil decreased cathepsin K expression in BMMs and the resorptive function of osteoclasts on dentine slices. Donepezil decreased RANK expression in BMMs, resulting in the inhibition of osteoclast differentiation with downregulation of c-Fos and upregulation of Id2. Moreover, administration of donepezil prevented RANKL-induced bone loss in vivo, which was associated with the inhibition of bone resorption by osteoclasts.

Conclusions

AChE promotes osteoclast differentiation in vitro. Donepezil inhibits osteoclast function in vitro and prevents bone loss by suppressing bone resorption in vivo, suggesting the possibility that donepezil reduces fracture risk in patients with Alzheimer's disease.

Readthrough acetylcholinesterase (AChE-R) and regulated necrosis: pharmacological targets for the regulation of ovarian functions?

Proliferation, differentiation and death of ovarian cells ensure orderly functioning of the female gonad during the reproductive phase, which ultimately ends with menopause in women. These processes are regulated by several mechanisms, including local signaling via neurotransmitters. Previous studies showed that ovarian non-neuronal endocrine cells produce acetylcholine (ACh), which likely acts as a trophic factor within the ovarian follicle and the corpus luteum via muscarinic ACh receptors. How its actions are restricted was unknown. We identified enzymatically active acetylcholinesterase (AChE) in human ovarian follicular fluid as a product of human granulosa cells. AChE breaks down ACh and thereby attenuates its trophic functions. Blockage of AChE by huperzine A increased the trophic actions as seen in granulosa cells studies. Among ovarian AChE variants, the readthrough isoform AChE-R was identified, which has further, non-enzymatic roles. AChE-R was found in follicular fluid, granulosa and theca cells, as well as luteal cells, implying that such functions occur in vivo. A synthetic AChE-R peptide (ARP) was used to explore such actions and induced in primary, cultured human granulosa cells a caspase-independent form of cell death with a distinct balloon-like morphology and the release of lactate dehydrogenase. The RIPK1 inhibitor necrostatin-1 and the MLKL-blocker necrosulfonamide significantly reduced this form of cell death. Thus a novel non-enzymatic function of AChE-R is to stimulate RIPK1/MLKL-dependent regulated necrosis (necroptosis). The latter complements a cholinergic system in the ovary, which determines life and death of ovarian cells. Necroptosis likely occurs in the primate ovary, as granulosa and luteal cells were immunopositive for phospho-MLKL, and hence necroptosis may contribute to follicular atresia and luteolysis. The results suggest that interference with the enzymatic activities of AChE and/or interference with necroptosis may be novel approaches to influence ovarian functions.

Wrecked regulation of intrinsically disordered proteins in diseases: pathogenicity of deregulated regulators

Biologically active proteins without stable tertiary structure are common in all known proteomes. Functions of these intrinsically disordered proteins (IDPs) are typically related to regulation, signaling, and control. Cellular levels of these important regulators are tightly regulated by a variety mechanisms ranging from firmly controlled expression to precisely targeted degradation. Functions of IDPs are controlled by binding to specific partners, alternative splicing, and posttranslational modifications among other means. In the norm, right amounts of precisely activated IDPs have to be present in right time at right places. Wrecked regulation brings havoc to the ordered world of disordered proteins, leading to protein misfolding, misidentification, and missignaling that give rise to numerous human diseases, such as cancer, cardiovascular disease, neurodegenerative diseases, and diabetes. Among factors inducing pathogenic transformations of IDPs are various cellular mechanisms, such as chromosomal translocations, damaged splicing, altered expression, frustrated posttranslational modifications, aberrant proteolytic degradation, and defective trafficking. This review presents some of the aspects of deregulated regulation of IDPs leading to human diseases.