Calcium and neurodegeneration

α-Synuclein pathology and mitochondrial dysfunction: Toxic partners in Parkinson's disease

Two major neuropathological features of Parkinson's disease (PD) are α-synuclein Lewy pathology and mitochondrial dysfunction. Although both α-synuclein pathology and mitochondrial dysfunction may independently contribute to PD pathogenesis, the interaction between these two factors is not yet fully understood. In this review, we discuss the physiological functions of α-synuclein and mitochondrial homeostasis in neurons as well as the pathological defects that ensue when these functions are disturbed in PD. Recent studies have highlighted that dysfunctional mitochondria can become sequestered within Lewy bodies, and cell biology studies have suggested that α-synuclein can directly impair mitochondrial function. There are also PD cases caused by genetic or environmental perturbation of mitochondrial homeostasis. Together, these studies suggest that mitochondrial dysfunction may be a common pathway to neurodegeneration in PD, triggered by multiple insults. We review the literature surrounding the interaction between α-synuclein and mitochondria and highlight open questions in the field that may be explored to advance our understanding of PD and develop novel, disease-modifying therapies.

Neuroimaging biomarkers of neuroprotection: Impact of voluntary versus enforced exercise in Alzheimer's disease models

Exercise is a promising strategy for preventing or delaying Alzheimer's disease (AD), yet its mechanisms remain unclear. We investigated how exercise influences brain structure, function, and behavior in a familial AD model. Mice underwent voluntary, voluntary plus enforced exercise, or remained sedentary. Neuroimaging included in vivo manganese-enhanced MRI (MEMRI). perfusion, and ex vivo diffusion MRI to assess morphometry, activity, cerebral blood flow (CBF), microstructural integrity and connectivity. Both exercise regimens induced structural and functional brain adaptations while reducing anhedonia. Voluntary exercise increased cortical and limbic volumes, particularly in the hippocampus, cingulate, and entorhinal cortex, supporting cognitive and emotional regulation. Adding enforced exercise influenced subcortical and sensory regions, including visual, motor and associative areas, supporting sensory-motor integration. MEMRI revealed increased activity in sensorimotor, limbic, and associative cortices, with voluntary exercise enhancing limbic and associative regions, and enforced exercise strengthening sensorimotor and subcortical circuits. White matter integrity improved in memory-associate pathways such as the corpus callosum, cingulum, and hippocampal commissure. Synaptic remodeling was observed in the cingulate cortex, anterior thalamic nuclei, and amygdala. Voluntary exercise enhanced CBF in the motor cortex and hippocampus, while enforced exercise limited these increases. Connectivity analyses revealed exercise-responsive networks spanning the cingulate cortex, entorhinal cortex, anterior thalamic nuclei, and basolateral amygdala, and associated tracts. Graph analyses linked running distance with increased thalamic, brainstem, and cerebellar connectivity, associating exercise intensity with plasticity. These findings highlight the ability of chronic exercise to modulate neuroimaging biomarkers through distinct but complementary pathways, reinforcing its potential as a neuroprotective intervention for AD.

Mitochondrial dysfunction in Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by progressive cognitive decline and distinct neuropathological features. The absence of a definitive cure presents a significant challenge in neurology and neuroscience. Early clinical manifestations, such as memory retrieval deficits and apathy, underscore the need for a deeper understanding of the disease's underlying mechanisms. While amyloid-β plaques and tau neurofibrillary tangles have dominated research efforts, accumulating evidence highlights mitochondrial dysfunction as a central factor in AD pathogenesis. Mitochondria, essential cellular organelles responsible for energy production necessary for neuronal function become impaired in AD, triggering several cellular consequences. Factors such as oxidative stress, disturbances in energy metabolism, failures in the mitochondrial quality control system, and dysregulation of calcium release are associated with mitochondrial dysfunction. These abnormalities are closely linked to the neurodegenerative processes driving AD development and progression. This review explores the intricate relationship between mitochondrial dysfunction and AD pathogenesis, emphasizing its role in disease onset and progression, while also considering its potential as a biomarker and a therapeutic target.

Neuroimaging Biomarkers of Neuroprotection: Impact of Voluntary versus Enforced Exercise in Alzheimer's Disease Models

Exercise is a promising strategy for preventing or delaying Alzheimer's disease (AD), yet its mechanisms remain unclear. We investigated how exercise influences brain structure, function, and behavior in a familial AD model. Mice underwent voluntary, voluntary plus enforced exercise, or remained sedentary. Neuroimaging included in vivo manganese-enhanced MRI (MEMRI). perfusion, and ex vivo diffusion MRI to assess morphometry, activity, cerebral blood flow (CBF), microstructural integrity and connectivity. Both exercise regimens induced structural and functional brain adaptations while reducing anhedonia. Voluntary exercise increased cortical and limbic volumes, particularly in the hippocampus, cingulate, and entorhinal cortex, supporting cognitive and emotional regulation. Adding enforced exercise influenced subcortical and sensory regions, including visual, motor and associative areas, supporting sensory-motor integration. MEMRI revealed increased activity in sensorimotor, limbic, and associative cortices, with voluntary exercise enhancing limbic and associative regions, and enforced exercise strengthening sensorimotor and subcortical circuits. White matter integrity improved in memory-associate pathways such as the corpus callosum, cingulum, and hippocampal commissure. Synaptic remodeling was observed in the cingulate cortex, anterior thalamic nuclei, and amygdala. Voluntary exercise enhanced CBF in the motor cortex and hippocampus, while enforced exercise limited these increases. Connectivity analyses revealed exercise-responsive networks spanning the cingulate cortex, entorhinal cortex, anterior thalamic nuclei, and basolateral amygdala, and associated tracts. Graph analyses linked running distance with increased thalamic, brainstem, and cerebellar connectivity, associating exercise intensity with plasticity. These findings highlight the ability of chronic exercise to modulate neuroimaging biomarkers through distinct but complementary pathways, reinforcing its potential as a neuroprotective intervention for AD.

Highlights

Exercise alters MRI biomarkers via distinct and partially overlapping mechanisms.Voluntary exercise boosts cortical and limbic regions for emotion and cognition.Enforced exercise strengthens subcortical and sensory areas for motor control.FA increases suggest memory tract reinforcement and grey matter remodelling.Graph analysis reveals plasticity in memory, emotion, and reward circuits.

Extracellular vesicles lay the ground for neuronal plasticity by restoring mitochondrial function, cell metabolism and immune balance

Extracellular vesicles (EVs) convey complex signals between cells that can be used to promote neuronal plasticity and neurological recovery in brain disease models. These EV signals are multimodal and context-dependent, making them unique therapeutic principles. This review analyzes how EVs released from various cell sources control neuronal metabolic function, neuronal survival and plasticity. Preferential sites of EV communication in the brain are interfaces between pre- and postsynaptic neurons at synapses, between astrocytes and neurons at plasma membranes or tripartite synapses, between oligodendrocytes and neurons at axons, between microglial cells/macrophages and neurons, and between cerebral microvascular cells and neurons. At each of these interfaces, EVs support mitochondrial function and cell metabolism under physiological conditions and orchestrate neuronal survival and plasticity in response to brain injury. In the injured brain, the promotion of neuronal survival and plasticity by EVs is tightly linked with EV actions on mitochondrial function, cell metabolism, oxidative stress and immune responses. Via the stabilization of cell metabolism and immune balance, neuronal plasticity responses are activated and functional neurological recovery is induced. As such, EV lay the ground for neuronal plasticity.

Glutathione S-transferase: A keystone in Parkinson's disease pathogenesis and therapy

Parkinson's disease is a progressive neurodegenerative disorder that predominantly affects motor function due to the loss of dopaminergic neurons in the substantia nigra. It presents significant challenges, impacting millions worldwide with symptoms such as tremors, rigidity, bradykinesia, and postural instability, leading to decreased quality of life and increased morbidity. The pathogenesis of Parkinson's disease is multifaceted, involving complex interactions between genetic susceptibility, environmental factors, and aging, with oxidative stress playing a central role in neuronal degeneration. Glutathione S-Transferase enzymes are critical in the cellular defense mechanism against oxidative stress, catalysing the conjugation of the antioxidant glutathione to various toxic compounds, thereby facilitating their detoxification. Recent research underscores the importance of Glutathione S-Transferase in the pathophysiology of Parkinson's disease, revealing that genetic polymorphisms in Glutathione S-Transferase genes influence the risk and progression of the disease. These genetic variations can affect the enzymatic activity of Glutathione S-Transferase, thereby modulating an individual's capacity to detoxify reactive oxygen species and xenobiotics, which are implicated in Parkinson's disease neuropathological processes. Moreover, biochemical studies have elucidated the role of Glutathione S-Transferase in not only maintaining cellular redox balance but also in modulating various cellular signalling pathways, highlighting its neuroprotective potential. From a therapeutic perspective, targeting Glutathione S-Transferase pathways offers promising avenues for the development of novel treatments aimed at enhancing neuroprotection and mitigating disease progression. This review explores the evident and hypothesized roles of Glutathione S-Transferase in Parkinson's disease, providing a comprehensive overview of its importance and potential as a target for therapeutic intervention.

Ferroptosis and cognitive impairment: Unraveling the link and potential therapeutic targets

Neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases, share key characteristics, notably cognitive impairment and significant cell death in specific brain regions. Cognition, a complex mental process allowing individuals to perceive time and place, is disrupted in these conditions. This consistent disruption suggests the possibility of a shared underlying mechanism across all neurodegenerative diseases. One potential common factor is the activation of pathways leading to cell death. Despite significant progress in understanding cell death pathways, no definitive treatments have emerged. This has shifted focus towards less-explored mechanisms like ferroptosis, which holds potential due to its involvement in oxidative stress and iron metabolism. Unlike apoptosis or necrosis, ferroptosis offers a novel therapeutic avenue due to its distinct biochemical and genetic underpinnings, making it a promising target in neurodegenerative disease treatment. Ferroptosis is distinguished from other cellular death mechanisms, by distinctive characteristics such as an imbalance of iron hemostasis, peroxidation of lipids in the plasma membrane, and dysregulated glutathione metabolism. In this review, we discuss the potential role of ferroptosis in cognitive impairment. We then summarize the evidence linking ferroptosis biomarkers to cognitive impairment brought on by neurodegeneration while highlighting recent advancements in our understanding of the molecular and genetic mechanisms behind the condition. Finally, we discuss the prospective therapeutic implications of targeting ferroptosis for the treatment of cognitive abnormalities associated with neurodegeneration, including natural and synthetic substances that suppress ferroptosis via a variety of mechanisms. Promising therapeutic candidates, including antioxidants and iron chelators, are being explored to inhibit ferroptosis and mitigate cognitive decline.

The etiology and prevention of early-stage tau pathology in higher cortical circuits: Insights from aging rhesus macaques

Aging rhesus macaques provide a unique model for learning how age and inflammation drive early-stage pathology in sporadic Alzheimer's disease, and for testing potential therapeutics. Unlike mice, aging macaques have extensive association cortices and inflammatory signaling similar to humans, are apolipoprotein E ε4 homozygotes, and naturally develop tau and amyloid pathology with marked cognitive deficits. Importantly, monkeys provide the unique opportunity to study early-stage, soluble hyperphosphorylated tau (p-tau), including p-tau217. As soluble p-tau is rapidly dephosphorylated post mortem, it is not captured in human brains except with biopsy material. However, new macaque data show that soluble p-tau is toxic to neurons and capable of seeding across cortical circuits. Extensive evidence indicates that age-related inflammatory signaling contributes to calcium dysregulation, which drives tau hyperphosphorylation and amyloid beta generation. Pharmacological studies in aged macaques suggest that inhibiting inflammation and restoring calcium regulation can reduce tau hyperphosphorylation with minimal side effects, appropriate for potential preventive therapeutics. HIGHLIGHTS: Aging monkeys provide a unique window into early stage, soluble phosphorylated tau (p-tau). Inflammation with advancing age leads to calcium dysregulation, p-tau, and amyloid beta (Aβ). Macaque research shows p-tau undergoes transsynaptic seeding early in the cortex. p-tau traps amyloid precursor protein-containing endosomes, which may increase Aβ and drive vicious cycles. Restoring calcium regulation in cortex reduced p-tau217 levels in aged macaques.

An overview of the genes and biomarkers in Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia and neurodegenerative disease characterized by neurofibrillary tangles (NFTs) and amyloid plaque. Familial AD is caused by mutations in the APP, PSEN1, and PSEN2 genes and these mutations result in the early onset of the disease. Sporadic AD usually affects older adults over the age of 65 years and is, therefore classified as late-onset AD (LOAD). Several risk factors associated with LOAD including the APOE gene have been identified. Moreover, GWAS studies have identified a wide array of genes and polymorphisms that are associated with LOAD risk. Currently, the diagnosis of AD involves the evaluation of memory and personality changes, cognitive impairment, and medical and family history to rule out other diseases. Laboratory tests to assess the biomarkers in the body fluids as well as MRI, CT, and PET scans to analyze the presence of plaques and NFTs are also included in the diagnosis of AD. It is important to diagnose AD before the onset of clinical symptoms, i.e. during the preclinical stage, to delay the progression and for better management of the disease. Research has been conducted to identify biomarkers of AD in the CSF, serum, saliva, and urine during the preclinical stage. Current research has identified several biomarkers and potential biomarkers in the body fluids that enhance diagnostic accuracy. Aside from genetics, other factors such as diet, physical activity, and lifestyle factors may influence the risk of developing AD. Clinical trials are underway to find potential biomarkers, diagnostic measures, and treatments for AD mainly in the preclinical stage. This review provides an overview of the genes and biomarkers of AD.

Metal Ion Signaling in Biomedicine

Complex multicellular organisms are composed of distinct tissues involving specialized cells that can perform specific functions, making such life forms possible. Species are defined by their genomes, and differences between individuals within a given species directly result from variations in their genetic codes. While genetic alterations can give rise to disease-causing acquisitions of distinct cell identities, it is now well-established that biochemical imbalances within a cell can also lead to cellular dysfunction and diseases. Specifically, nongenetic chemical events orchestrate cell metabolism and transcriptional programs that govern functional cell identity. Thus, imbalances in cell signaling, which broadly defines the conversion of extracellular signals into intracellular biochemical changes, can also contribute to the acquisition of diseased cell states. Metal ions exhibit unique chemical properties that can be exploited by the cell. For instance, metal ions maintain the ionic balance within the cell, coordinate amino acid residues or nucleobases altering folding and function of biomolecules, or directly catalyze specific chemical reactions. Thus, metals are essential cell signaling effectors in normal physiology and disease. Deciphering metal ion signaling is a challenging endeavor that can illuminate pathways to be targeted for therapeutic intervention. Here, we review key cellular processes where metal ions play essential roles and describe how targeting metal ion signaling pathways has been instrumental to dissecting the biochemistry of the cell and how this has led to the development of effective therapeutic strategies.

Mitochondria as a Therapeutic Target: Focusing on Traumatic Brain Injury

Mitochondria are organelles of eukaryotic cells delimited by two membranes and cristae that consume oxygen to produce adenosine triphosphate (ATP), and are involved in the synthesis of vital metabolites, calcium homeostasis, and cell death mechanisms. Strikingly, normal mitochondria function as an integration center between multiple conditions that determine neural cell homeostasis, whereas lesions that lead to mitochondrial dysfunction can desynchronize cellular functions, thus contributing to the pathophysiology of traumatic brain injury (TBI). In addition, TBI leads to impaired coupling of the mitochondrial electron transport system with oxidative phosphorylation that provides most of the energy needed to maintain vital functions, ionic homeostasis, and membrane potentials. Furthermore, mitochondrial metabolism produces signaling molecules such as reactive oxygen species (ROS), regulating calcium levels and controlling the expression profile of intrinsic pro-apoptotic effectors influenced by TBI. Hence, the set of these functions is widely referred to as 'mitochondrial function', although the complexity of the relationship between such components limits such a definition. In this review, we present mitochondria as a therapeutic target, focus on TBI, and discuss aspects of mitochondrial structure and function.

Dietary Intake, Mediterranean and Nordic Diet Adherence in Alzheimer's Disease and Dementia: A Systematic Review

BACKGROUND/OBJECTIVES

Dementia is not a single disease but an umbrella term that encompasses a range of symptoms, such as memory loss and cognitive impairments, which are severe enough to disrupt daily life. One of the most common forms of dementia is Alzheimer's Disease (AD), a complex neurodegenerative condition influenced by both genetic and environmental factors. Recent research has highlighted diet as a potential modifiable risk factor for AD. Decades of research have explored the role of dietary patterns, including the Mediterranean Diet (MD) and its components, in neuroprotection and cognitive health. Systematic review examines studies investigating the impact of the Mediterranean Diet, Mediterranean-like diets, the Nordic Diet (ND), dietary intake patterns, and specific components such as extra virgin olive oil and rapeseed oil on cognitive function, disease onset, and progression in AD and dementia.

METHODS

A comprehensive search of PubMed, the Directory of Open Access Journals, and the Social Science Research Network was conducted independently by two reviewers using predefined search terms. The search period included studies from 2006 to 2024. Eligible studies meeting the inclusion criteria were systematically reviewed, yielding 88 studies: 85 focused on the MD and its relationship to AD and dementia, while only 3 investigated the ND.

RESULTS

The findings suggest that adherence to the Mediterranean and Nordic diets is generally associated with improved cognitive function and delayed cognitive decline and that adherence to both these diets can improve cognitive function. Some studies identified that higher legume consumption decreased dementia incidence, while fruits and vegetables, carbohydrates, and eggs lowered dementia prevalence. Most studies demonstrated that high MD or ND adherence was associated with better cognitive function and a lower risk of poor cognition in comparison to individuals with lower MD or ND adherence. However, some studies reported no significant benefits of the MD on cognitive outcomes, while two studies indicated that higher red meat consumption was linked to better cognitive function.

CONCLUSION

Despite promising trends, the evidence remains varying across studies, underscoring the need for further research to establish definitive associations between diet and cognitive function. These findings highlight the essential role of dietary interventions in the prevention and management of dementia and AD, therefore offering critical insights into the underlying mechanisms by which the diet may impact brain health.

High-frequency MHz-order vibration enables cell membrane remodeling and lipid microdomain manipulation

We elucidate the mechanism underpinning a recently discovered phenomenon in which cells respond to MHz-order mechanostimuli. Deformations induced along the plasma membrane under these external mechanical cues are observed to decrease the membrane tension, which, in turn, drives transient and reversible remodeling of its lipid structure. In particular, the increase and consequent coalescence of ordered lipid microdomains leads to closer proximity to mechanosensitive ion channels-Piezo1, in particular-that, due to crowding, results in their activation to mobilize influx of calcium (Ca2+) ions into the cell. It is the modulation of this second messenger that is responsible for the downstream signaling and cell fates that ensue. In addition, we show that such spatiotemporal control over the membrane microdomains in cells-without necessitating biochemical factors-facilitates aggregation and association of intrinsically disordered tau proteins in neuroblastoma cells, and their transformation to pathological conditions implicated in neurodegenerative diseases, thereby paving the way for the development of therapeutic intervention strategies.

Mitochondrial dysfunction as a therapeutic strategy for neurodegenerative diseases: Current insights and future directions

Neurodegenerative diseases, as common diseases in the elderly, tend to become younger due to environmental changes, social development and other factors. They are mainly characterized by progressive loss or dysfunction of neurons in the central or peripheral nervous system, and common diseases include Parkinson's disease, Alzheimer's disease, Huntington's disease and so on. Mitochondria are important organelles for adenosine triphosphate (ATP) production in the brain. In recent years, a large amount of evidence has shown that mitochondrial dysfunction plays a direct role in neurodegenerative diseases, which is expected to provide new ideas for the treatment of related diseases. This review will summarize the main mechanisms of mitochondrial dysfunction in neurodegenerative diseases, as well as collating recent advances in the study of mitochondrial disorders and new therapies.

Liquid-liquid phase separation and conformational strains of α-Synuclein: implications for Parkinson's disease pathogenesis

Parkinson's disease (PD) and other synucleinopathies are characterized by the aggregation and deposition of alpha-synuclein (α-syn) in brain cells, forming insoluble inclusions such as Lewy bodies (LBs) and Lewy neurites (LNs). The aggregation of α-syn is a complex process involving the structural conversion from its native random coil to well-defined secondary structures rich in β-sheets, forming amyloid-like fibrils. Evidence suggests that intermediate species of α-syn aggregates formed during this conversion are responsible for cell death. However, the molecular events involved in α-syn aggregation and its relationship with disease onset and progression remain not fully elucidated. Additionally, the clinical and pathological heterogeneity observed in various synucleinopathies has been highlighted. Liquid-liquid phase separation (LLPS) and condensate formation have been proposed as alternative mechanisms that could underpin α-syn pathology and contribute to the heterogeneity seen in synucleinopathies. This review focuses on the role of the cellular environment in α-syn conformational rearrangement, which may lead to pathology and the existence of different α-syn conformational strains with varying toxicity patterns. The discussion will include cellular stress, abnormal LLPS formation, and the potential role of LLPS in α-syn pathology.

Recent Advances and Therapeutic Benefits of Glucagon-Like Peptide-1 (GLP-1) Agonists in the Management of Type 2 Diabetes and Associated Metabolic Disorders

Glucagon-like peptide-1 (GLP-1) agonists have emerged as a groundbreaking class of medications for managing type 2 diabetes and associated metabolic disorders. These agents not only improve glycemic control by increasing insulin secretion and reducing glucagon levels but also promote significant weight loss, enhance cardiovascular and renal health, and offer potential neuroprotective benefits. Their multifaceted mechanisms include appetite suppression, increased energy expenditure, and direct neuroprotective effects. GLP-1 agonists have shown recent benefits in Obstructive Sleep Apnea, and the treatment of neurodegenerative diseases such as Alzheimer's and Parkinson's, as well as reducing the risk of stroke. This review highlights the therapeutic potential of GLP-1 agonists in diabetes management and beyond, advocating for continued research to optimize their clinical use and explore new therapeutic avenues.

Stable potassium isotope ratios in human blood serum towards biomarker development in Alzheimer's disease

The Alzheimer's disease (AD)-affected brain purges K with concurrently increasing serum K, suggesting brain-blood K transferal. Here, natural stable K isotope ratios-δ41K-of human serum samples were characterized in an AD biomarker pilot study (plus two paired Li-heparin and potassium ethylenediaminetetraacetic acid [K-EDTA] plasma samples). AD serum was found to have a significantly lower mean δ41K relative to controls. To mechanistically explore this change, novel ab initio calculations (density functional theory) of relative K isotope compositions between hydrated K+ and organically bound K were performed, identifying hydrated K+ as isotopically light (lower δ41K) compared to organically bound K. Taken together with literature, serum δ41K and density functional theory results are consistent with efflux of hydrated K+ from the brain to the bloodstream, manifesting a measurable decrease in serum δ41K. These data introduce serum δ41K for further investigation as a minimally invasive AD biomarker, with cost, scalability, and stability advantages over current techniques.

Recent advances in Alzheimer's disease: Mechanisms, clinical trials and new drug development strategies

Alzheimer's disease (AD) stands as the predominant form of dementia, presenting significant and escalating global challenges. Its etiology is intricate and diverse, stemming from a combination of factors such as aging, genetics, and environment. Our current understanding of AD pathologies involves various hypotheses, such as the cholinergic, amyloid, tau protein, inflammatory, oxidative stress, metal ion, glutamate excitotoxicity, microbiota-gut-brain axis, and abnormal autophagy. Nonetheless, unraveling the interplay among these pathological aspects and pinpointing the primary initiators of AD require further elucidation and validation. In the past decades, most clinical drugs have been discontinued due to limited effectiveness or adverse effects. Presently, available drugs primarily offer symptomatic relief and often accompanied by undesirable side effects. However, recent approvals of aducanumab (1) and lecanemab (2) by the Food and Drug Administration (FDA) present the potential in disrease-modifying effects. Nevertheless, the long-term efficacy and safety of these drugs need further validation. Consequently, the quest for safer and more effective AD drugs persists as a formidable and pressing task. This review discusses the current understanding of AD pathogenesis, advances in diagnostic biomarkers, the latest updates of clinical trials, and emerging technologies for AD drug development. We highlight recent progress in the discovery of selective inhibitors, dual-target inhibitors, allosteric modulators, covalent inhibitors, proteolysis-targeting chimeras (PROTACs), and protein-protein interaction (PPI) modulators. Our goal is to provide insights into the prospective development and clinical application of novel AD drugs.

Vicious cycle of oxidative stress and neuroinflammation in pathophysiology of chronic vascular encephalopathy

Chronic vascular encephalopathy (CVE) is a frequent cause of vascular mild cognitive impairment and dementia, which significantly worsens the quality of life, especially in the elderly population. CVE is a result of chronic cerebral hypoperfusion, characterized by prolonged limited blood flow to the brain. This causes insufficient oxygenation of the brain leading to hypoxia. The latter can trigger a series of events associated with the development of oxidative/reductive stresses and neuroinflammation. Addressing the gap in knowledge regarding oxidative and reductive stresses in the development of vascular disorders and neuroinflammation can give a start to new directions of research in the context of CVE. In this review, we consider the hypoxia-induced molecular challenges involved in the pathophysiology of CVE, focusing on oxidative stress and neuroinflammation, which are combined in a vicious cycle of neurodegeneration. We also briefly describe therapeutic approaches to the treatment of CVE and outline the prospects for the use of sulforaphane, an isothiocyanate common in cruciferous plants, and vitamin D to break the vicious cycle and alleviate the cognitive impairments characteristic of patients with CVE.

Modeling Alzheimer's disease using human cell derived brain organoids and 3D models

Age-related neurodegenerative diseases, like Alzheimer's disease (AD), are challenging diseases for those affected with no cure and limited treatment options. Functional, human derived brain tissues that represent the diverse genetic background and cellular subtypes contributing to sporadic AD (sAD) are limited. Human stem cell derived brain organoids recapitulate some features of human brain cytoarchitecture and AD-like pathology, providing a tool for illuminating the relationship between AD pathology and neural cell dysregulation leading to cognitive decline. In this review, we explore current strategies for implementing brain organoids in the study of AD as well as the challenges associated with investigating age-related brain diseases using organoid models.

PIEZO1 as a new target for hyperglycemic stress-induced neuropathic injury: The potential therapeutic role of bezafibrate

Hyperglycemic stress can directly lead to neuronal damage. The mechanosensitive ion channel PIEZO1 can be activated in response to hyperglycemia, but its role in hyperglycemic neurotoxicity is unclear. The role of PIEZO1 in hyperglycemic neurotoxicity was explored by constructing a hyperglycemic mouse model and a high-glucose HT22 cell model. The results showed that PIEZO1 was significantly upregulated in response to high glucose stress. In vitro experiments have shown that high glucose stress induces changes in neuronal cell morphology and membrane tension, a key mechanism for PIEZO1 activation. In addition, high glucose stress upregulates serum/glucocorticoid-regulated kinase-1 (SGK1) and activates PIEZO1 through the Ca2+ pool and store-operated calcium entry (SOCE). PIEZO1-mediated Ca2+ influx further enhances SGK1 and SOCE, inducing intracellular Ca2+ peaks in neurons. PIEZO1 mediated intracellular Ca2+ elevation leads to calcium/calmodulin-dependent protein kinase 2α (CaMK2α) overactivation, which promotes oxidative stress and apoptosis signalling through p-CaMK2α/ERK/CREB and ox-CaMK2α/MAPK p38/NFκB p65 pathways, subsequently inducing synaptic damage and cognitive impairment in mice. The intron miR-107 of pantothenic kinase 1 (PANK1) is highly expressed in the brain and has been found to target PIEZO1 and SGK1. The PANK1 receptor is activated by peroxisome proliferator-activated receptor α (PPARα), an activator known to upregulate miR-107 levels in the brain. The clinically used lipid-lowering drug bezafibrate, a known PPARα activator, may upregulate miR-107 through the PPARɑ/PANK1 pathway, thereby inhibiting PIEZO1 and improving hyperglycemia-induced neuronal cell damage. This study provides a new idea for the pathogenesis and drug treatment of hyperglycemic neurotoxicity and diabetes-related cognitive dysfunction.

Sink or swim: Does a worm paralysis phenotype hold clues to neurodegenerative disease?

Receiving a neurodegenerative disease (NDD) diagnosis, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, or amyotrophic lateral sclerosis, is devastating, particularly given the limited options for treatment. Advances in genetic technologies have allowed for efficient modeling of NDDs in animals and brought hope for new disease-modifying medications. The complexity of the mammalian brain and the costs and time needed to identify and develop therapeutic leads limits progress. Modeling NDDs in invertebrates, such as the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans, offers orders of magnitude increases in speed of genetic analysis and manipulation, and can be pursued at substantially reduced cost, providing an important, platform complement and inform research with mammalian NDD models. In this review, we describe how our efforts to exploit C. elegans for the study of neural signaling and health led to the discovery of a paralytic phenotype (swimming-induced paralysis) associated with altered dopamine signaling and, surprisingly, to the discovery of a novel gene and pathway whose dysfunction in glial cells triggers neurodegeneration. Research to date on swip-10 and its putative mammalian ortholog MBLAC1, suggests that a tandem analysis will offer insights into NDD mechanisms and insights into novel, disease-modifying therapeutics.

Glutamic Acid Modified Gold Nanorod Sensor for the Detection of Calcium ions in Neuronal Cells

Calcium (Ca2+) ions play a crucial role in the functioning of neurons, governing various aspects of neuronal activity such as rapid modulation and alterations in gene expression. Ca2+ signaling has a significant impact on the development of diseases and the impairment of neuronal functions. Herein, the study reports a Ca2+ ion sensor in neuronal cells using a gold nanorod. The gold nanorod (GA-GNR) conjugated glutamic acid developed in the study was used as a nano-bio probe for the experimental and in vitro detection of calcium. The nanosensor is colloidally stable, preserves plasmonic properties, and shows good viability in neuronal cells, as well as promoting neuron cell line growth. The cytotoxicity and cell penetration of the nanosensor are studied using Raman spectroscopy, brightfield and darkfield microscopy imaging, and MTT assays. The quantification of Ca2+ ions in neuronal cells is determined by monitoring the surface plasmon resonance (SPR) of the GA-GNR. The change in the intensity profile in the presence of Ca2+ incubated neurons was effectively used to develop a portable prototype of an optical Ca2+ sensor, proposing it as a tool for neurodegenerative disease diagnosis and neuromodulation evaluation.

Identification of compounds that cause axonal dieback without cytotoxicity in dorsal root ganglia explants and intervertebral disc cells with potential to treat pain via denervation

Low back pain, knee osteoarthritis, and cancer patients suffer from chronic pain. Aberrant nerve growth into intervertebral disc, knee, and tumors, are common pathologies that lead to these chronic pain conditions. Axonal dieback induced by capsaicin (Caps) denervation has been FDA-approved to treat painful neuropathies and knee osteoarthritis but with short-term efficacy and discomfort. Herein, we propose to evaluate pyridoxine (Pyr), vincristine sulfate (Vcr) and ionomycin (Imy) as axonal dieback compounds for denervation with potential to alleviate pain. Previous literature suggests Pyr, Vcr, and Imy can cause undesired axonal degeneration, but no previous work has evaluated axonal dieback and cytotoxicity on adult rat dorsal root ganglia (DRG) explants. Thus, we performed axonal dieback screening using adult rat DRG explants in vitro with Caps as a positive control and assessed cytotoxicity. Imy inhibited axonal outgrowth and slowed axonal dieback, while Pyr and Vcr at high concentrations produced significant reduction in axon length and robust axonal dieback within three days. DRGs treated with Caps, Vcr, or Imy had increased DRG cytotoxicity compared to matched controls, but overall cytotoxicity was minimal and at least 88% lower compared to lysed DRGs. Pyr did not lead to any DRG cytotoxicity. Further, neither Pyr nor Vcr triggered intervertebral disc cell death or affected cellular metabolic activity after three days of incubation in vitro. Overall, our findings suggest Pyr and Vcr are not toxic to DRGs and intervertebral disc cells, and there is potential for repurposing these compounds for axonal dieback compounds to cause local denervation and alleviate pain.

Beneficial versus Detrimental Effects of Complement-Microglial Interactions in Alzheimer's Disease

Research indicates that brain-region-specific synapse loss and dysfunction are early hallmarks and stronger neurobiological correlates of cognitive decline in Alzheimer's disease (AD) than amyloid plaque and neurofibrillary tangle counts or neuronal loss. Even though the precise mechanisms underlying increased synaptic pruning in AD are still unknown, it has been confirmed that dysregulation of the balance between complement activation and inhibition is a crucial driver of its pathology. The complement includes three distinct activation mechanisms, with the activation products C3a and C5a, potent inflammatory effectors, and a membrane attack complex (MAC) leading to cell lysis. Besides pro-inflammatory cytokines, the dysregulated complement proteins released by activated microglia bind to amyloid β at the synaptic regions and cause the microglia to engulf the synapses. Additionally, research indicating that microglia-removed synapses are not always degenerating and that suppression of synaptic engulfment can repair cognitive deficits points to an essential opportunity for intervention that can prevent the loss of intact synapses. In this study, we focus on the latest research on the role and mechanisms of complement-mediated microglial synaptic pruning at different stages of AD to find the right targets that could interfere with complement dysregulation and be relevant for therapeutic intervention at the early stages of the disease.

Epigallocatechin gallate improves neuronal damage in animal model of ischemic stroke and glutamate-exposed neurons via modulation of hippocalcin expression

Epigallocatechin gallate (EGCG) is a polyphenolic component of green tea that has anti-oxidative and anti-inflammatory effects in neurons. Ischemic stroke is a major neurological disease that causes irreversible brain disorders. It increases the intracellular calcium concentration and induces apoptosis. The regulation of intracellular calcium concentration is important to maintain the function of the nervous system. Hippocalcin is a neuronal calcium sensor protein that controls intracellular calcium concentration. We investigated whether EGCG treatment regulates the expression of hippocalcin in stroke animal model and glutamate-induced neuronal damage. We performed middle cerebral artery occlusion (MCAO) to induce cerebral ischemia. EGCG (50 mg/kg) or phosphate buffered saline was injected into the abdominal cavity just before MCAO surgery. The neurobehavioral tests were performed 24 h after MCAO surgery and cerebral cortex tissue was collected. MCAO damage induced severe neurobehavioral disorders, increased infarct volume, and decreased the expression of hippocalcin in the cerebral cortex. However, EGCG treatment improved these deficits and alleviated the decrease in hippocalcin expression in cerebral cortex. In addition, EGCG dose-dependently alleviated neuronal cell death and intracellular calcium overload in glutamate-exposed neurons. Glutamate exposure reduced hippocalcin expression, decreased Bcl-2 expression, and increased Bax expression. However, EGCG treatment mitigated these changes caused by glutamate toxicity. EGCG also attenuated the increase in caspase-3 and cleaved caspase-3 expressions caused by glutamate exposure. The effect of EGCG was more pronounced in non-transfected cells than in hippocalcin siRNA-transfected cells. These findings demonstrate that EGCG protects neurons against glutamate toxicity through the regulation of Bcl-2 family proteins and caspase-3. It is known that hippocalcin exerts anti-apoptotic effect through the modulation of apoptotic pathway. Thus, we can suggest evidence that EGCG has a neuroprotective effect by regulating hippocalcin expression in ischemic brain damage and glutamate-exposed cells.

Tau-S214 Phosphorylation Inhibits Fyn Kinase Interaction and Increases the Decay Time of NMDAR-mediated Current

Fyn kinase SH3 domain interaction with PXXP motif in the Tau protein is implicated in AD pathology and is central to NMDAR function. Among seven PXXP motifs localized in proline-rich domain of Tau protein, tandem 5th and 6th PXXP motifs are critical to Fyn-SH3 domain interaction. Here, we report the crystal structure of Fyn-SH3 -Tau (207-221) peptide consisting of 5th and 6th PXXP motif complex to 1.01 Å resolution. Among five AD-specific phosphorylation sites encompassing the 5th and 6th PXXP motifs, only S214 residue showed interaction with SH3 domain. Biophysical studies showed that Tau (207-221) with S214-phosphorylation (pS214) inhibits its interaction with Fyn-SH3 domain. The individual administration of Tau (207-221) with/without pS214 peptides to a single neuron increased the decay time of evoked NMDA current response. Recordings of spontaneous NMDA EPSCs at +40 mV indicate an increase in frequency and amplitude of events for the Tau (207-221) peptide. Conversely, the Tau (207-221) with pS214 peptide exhibited a noteworthy amplitude increase alongside a prolonged decay time. These outcomes underscore the distinctive modalities of action associated with each peptide in the study. Overall, this study provides insights into how Tau (207-221) with/without pS214 affects the molecular framework of NMDAR signaling, indicating its involvement in Tau-related pathogenesis.

Neuroprotective Effects of Cannabispirenone A against NMDA-Induced Excitotoxicity in Differentiated N2a Cells

The endocannabinoid system is found throughout the central nervous system, and its cannabinoids receptor 1 is critical in preventing neurotoxicity caused by N-methyl-D-aspartate receptor activation (NMDARs). The activity of NMDARs places demands on endogenous cannabinoids to regulate their calcium currents. Endocannabinoids keep NMDAR activity within safe limits, protecting neural cells from excitotoxicity. Cannabinoids are remembered to deliver this outcome by repressing presynaptic glutamate discharge or obstructing postsynaptic NMDAR-managed flagging pathways. The endocannabinoid system must exert a negative influence proportional to the strength of NMDAR signaling for such control to be effective. The goal of this paper is to draw the attention towards the neuroprotective mechanism of constituents of Cannabis sativa against NMDA-induced excitotoxic result. Phytochemical investigation of the cannabis flowers led to the isolation of nine secondary metabolites. A spiro-compound, Cannabispirenone A, which on treatment of the cells prior to NMDA exposure significantly increases cell survival while decreasing ROS production, lipid peroxidation, and intracellular calcium. Our findings showed that this compound showed neuroprotection against NMDA-induced excitotoxic insult, has antioxidative properties, and increased cannabinoid receptor 1 expression, which may be involved in the signaling pathway for this neuroprotection.

43Ca MAS-DNP NMR of Frozen Solutions for the Investigation of Calcium Ion Complexation

Calcium ion complexation in aqueous solutions is of paramount importance in biology as it is related to cell signaling, muscle contraction, or biomineralization. However, Ca2+-complexes are dynamic soluble entities challenging to describe at the molecular level. Nuclear magnetic resonance appears as a method of choice to probe Ca2+-complexes. However, 43Ca NMR exhibits severe limitations arising from the low natural abundance coupled to the low gyromagnetic ratio and the quadrupolar nature of 43Ca, which overall make it a very unreceptive nucleus. Here, we show that 43Ca dynamic nuclear polarization (DNP) NMR of 43Ca-labeled frozen solutions is an efficient approach to enhance the NMR receptivity of 43Ca and to obtain structural insights about calcium ions complexed with representative ligands including water molecules, ethylenediaminetetraacetic acid (EDTA), and l-aspartic acid (l-Asp). In these conditions and in combination with numerical simulations and calculations, we show that 43Ca nuclei belonging to Ca2+ complexed to the investigated ligands exhibit rather low quadrupolar couplings (with CQ typically ranging from 0.6 to 1 MHz) due to high symmetrical environments and potential residual dynamics in vitrified solutions at a temperature of 100 K. As a consequence, when 1H→43Ca cross-polarization (CP) is used to observe 43Ca central transition, "high-power" νRF(43Ca) conditions, typically used to detect spin 1/2 nuclei, provide ∼120 times larger sensitivity than "low-power" conditions usually employed for detection of quadrupolar nuclei. These "high-power" CPMAS conditions allow two-dimensional (2D) 1H-43Ca HetCor spectra to be readily recorded, highlighting various Ca2+-ligand interactions in solution. This significant increase in 43Ca NMR sensitivity results from the combination of distinct advantages: (i) an efficient 1H-mediated polarization transfer from DNP, resembling the case of low-natural-abundance spin 1/2 nuclei, (ii) a reduced dynamics, allowing the use of CP as a sensitivity enhancement technique, and (iii) the presence of a relatively highly symmetrical Ca environment, which, combined to residual dynamics, leads to the averaging of the quadrupolar interaction and hence to efficient high-power CP conditions. Interestingly, these results indicate that the use of high-power CP conditions is an effective way of selecting symmetrical and/or dynamic 43Ca environments of calcium-containing frozen solution, capable of filtering out more rigid and/or anisotropic 43Ca sites characterized by larger quadrupolar constants. This approach could open the way to the atomic-level investigation of calcium environments in more complex, heterogeneous frozen solutions, such as those encountered at the early stages of calcium phosphate or calcium carbonate biomineralization events.

Kinase signalling adaptation supports dysfunctional mitochondria in disease

Mitochondria form a critical control nexus which are essential for maintaining correct tissue homeostasis. An increasing number of studies have identified dysregulation of mitochondria as a driver in cancer. However, which pathways support and promote this adapted mitochondrial function? A key hallmark of cancer is perturbation of kinase signalling pathways. These pathways include mitogen activated protein kinases (MAPK), lipid secondary messenger networks, cyclic-AMP-activated (cAMP)/AMP-activated kinases (AMPK), and Ca2+/calmodulin-dependent protein kinase (CaMK) networks. These signalling pathways have multiple substrates which support initiation and persistence of cancer. Many of these are involved in the regulation of mitochondrial morphology, mitochondrial apoptosis, mitochondrial calcium homeostasis, mitochondrial associated membranes (MAMs), and retrograde ROS signalling. This review will aim to both explore how kinase signalling integrates with these critical mitochondrial pathways and highlight how these systems can be usurped to support the development of disease. In addition, we will identify areas which require further investigation to fully understand the complexities of these regulatory interactions. Overall, this review will emphasize how studying the interaction between kinase signalling and mitochondria improves our understanding of mitochondrial homeostasis and can yield novel therapeutic targets to treat disease.

Motor neuron activity enhances the proteomic stress caused by autophagy defects in the target muscle

Several lines of evidence demonstrate that increased neuronal excitability can enhance proteomic stress. For example, epilepsy can enhance the proteomic stress caused by the expression of certain aggregation-prone proteins implicated in neurodegeneration. However, unanswered questions remain concerning the mechanisms by which increased neuronal excitability accomplishes this enhancement. Here we test whether increasing neuronal excitability at a particular identified glutamatergic synapse, the Drosophila larval neuromuscular junction, can enhance the proteomic stress caused by mutations in the ER fusion/GTPase gene atlastin (atl). It was previously shown that larval muscle from the atl2 null mutant is defective in autophagy and accumulates protein aggregates containing ubiquitin (poly-UB aggregates). To determine if increased neuronal excitability might enhance the increased proteomic stress caused by atl2, we activated the TrpA1-encoded excitability channel within neurons. We found that TrpA1 activation had no effect on poly-UB aggregate accumulation in wildtype muscle, but significantly increased poly-UB aggregate number in atl2 muscle. Previous work has shown that atl loss from either neuron or muscle increases muscle poly-UB aggregate number. We found that neuronal TrpA1 activation enhanced poly-UB aggregate number when atl was removed from muscle, but not from neuron. Neuronal TrpA1 activation enhanced other phenotypes conferred by muscle atl loss, such as decreased pupal size and decreased viability. Taken together, these results indicate that the proteomic stress caused by muscle atl loss is enhanced by increasing neuronal excitability.

A surge of cytosolic calcium dysregulates lysosomal function and impairs autophagy flux during cupric chloride-induced neuronal death

Autophagy is a degradative pathway that plays an important role in maintaining cellular homeostasis. Dysfunction of autophagy is associated with the progression of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Although one of the typical features of brain aging is an accumulation of redox-active metals that eventually lead to neurodegeneration, a plausible link between trace metal-induced neurodegeneration and dysregulated autophagy has not been clearly determined. Here, we used a cupric chloride-induced neurodegeneration model in MN9D dopaminergic neuronal cells along with ultrastructural and biochemical analyses to demonstrate impaired autophagic flux with accompanying lysosomal dysfunction. We found that a surge of cytosolic calcium was involved in cupric chloride-induced dysregulated autophagy. Consequently, buffering of cytosolic calcium by calbindin-D28K overexpression or co-treatment with the calcium chelator BAPTA attenuated the cupric chloride-induced impairment in autophagic flux by ameliorating dysregulation of lysosomal function. Thus, these events allowed the rescue of cells from cupric chloride-induced neuronal death. These phenomena were largely confirmed in cupric chloride-treated primary cultures of cortical neurons. Taken together, these results suggest that abnormal accumulation of trace metal elements and a resultant surge of cytosolic calcium leads to neuronal death by impairing autophagic flux at the lysosomal level.

Computer simulations predict the impact of neuronal atrophy on the calcium dynamics in Huntington's disease

One of the early hallmarks of Huntington's disease (HD) is neuronal cell atrophy, especially in the striatum, underlying motor dysfunction in HD. Here using a computer model, we have predicted the impact of cell shrinkage on calcium dynamics at the cellular level. Our model indicates that as cytosolic volume decreases, the amplitude of calcium transients increases and the endoplasmic reticulum (ER) becomes more leaky due to calcium-induced calcium release and a "toxic" positive feedback mechanism mediated by ryanodine receptors that greatly increases calcium release into the cytosol. The excessive calcium release from ER saturates the calcium buffering capacity of calbindin and forces further accumulation of free calcium in the cytosol and cellular compartments including mitochondria. This leads to imbalance of calcium in both cytosol and ER regions. Excessive calcium accumulation in the cytosol can damage the mitochondria resulting in metabolic dysfunction in the cell consistent with the pathology of HD. Our computational model points toward potential drug targets and can accelerate and greatly help the experimental studies of HD paving the way for treatments of patients suffering from HD.

Targeting calcium homeostasis and impaired inter-organelle crosstalk as a potential therapeutic approach in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor symptoms such as tremors, rigidity, and bradykinesia. Current therapeutic strategies for PD are limited and mainly involve symptomatic relief, with no available treatment for the underlying causes of the disease. Therefore, there is a need for new therapeutic approaches that target the underlying pathophysiological mechanisms of PD. Calcium homeostasis is an essential process for maintaining proper cellular function and survival, including neuronal cells. Calcium dysregulation is also observed in various organelles, including the endoplasmic reticulum (ER), mitochondria, and lysosomes, resulting in organelle dysfunction and impaired inter-organelle communication. The ER, as the primary calcium reservoir, is responsible for folding proteins and maintaining calcium homeostasis, and its dysregulation can lead to protein misfolding and neurodegeneration. The crosstalk between ER and mitochondrial calcium signaling is disrupted in PD, leading to neuronal dysfunction and death. In addition, a lethal network of calcium cytotoxicity utilizes mitochondria, ER and lysosome to destroy neurons. This review article focused on the complex role of calcium dysregulation and its role in aggravating functioning of organelles in PD so as to provide new insight into therapeutic strategies for treating this disease. Targeting dysfunctional organelles, such as the ER and mitochondria and lysosomes and whole network of calcium dyshomeostasis can restore proper calcium homeostasis and improve neuronal function. Additionally targeting calcium dyshomeostasis that arises from miscommunication between several organelles can be targeted so that therapeutic effects of calcium are realised in whole cellular territory.

Cytosolic calcium: Judge, jury and executioner of neurodegeneration in Alzheimer's disease and beyond

This review discusses the driving principles that may underlie neurodegeneration in dementia, represented most dominantly by Alzheimer's disease (AD). While a myriad of different disease risk factors contribute to AD, these ultimately converge to a common disease outcome. Based on decades of research, a picture emerges where upstream risk factors combine in a feedforward pathophysiological cycle, culminating in a rise of cytosolic calcium concentration ([Ca2+ ]c ) that triggers neurodegeneration. In this framework, positive AD risk factors entail conditions, characteristics, or lifestyles that initiate or accelerate self-reinforcing cycles of pathophysiology, whereas negative risk factors or therapeutic interventions, particularly those mitigating elevated [Ca2+ ]c , oppose these effects and therefore have neuroprotective potential.

Hyperactivity of medial prefrontal cortex pyramidal neurons occurs in a mouse model of early-stage Alzheimer's disease without β-amyloid accumulation

The normal function of the medial prefrontal cortex (mPFC) is essential for regulating neurocognition, but it is disrupted in the early stages of Alzheimer's disease (AD) before the accumulation of Aβ and the appearance of symptoms. Despite this, little is known about how the functional activity of medial prefrontal cortex pyramidal neurons changes as Alzheimer's disease progresses during aging. We used electrophysiological techniques (patch-clamping) to assess the functional activity of medial prefrontal cortex pyramidal neurons in the brain of 3xTg-Alzheimer's disease mice modeling early-stage Alzheimer's disease without Aβ accumulation. Our results indicate that firing rate and the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) were significantly increased in medial prefrontal cortex neurons from young Alzheimer's disease mice (4-5-month, equivalent of <30-year-old humans) compared to age-matched control mice. Blocking ionotropic glutamatergic NMDA receptors, which regulate neuronal excitability and Ca2+ homeostasis, abolished this neuronal hyperactivity. There were no changes in Ca2+ influx through the voltage-gated Ca2+ channels (VGCCs) or inhibitory postsynaptic activity in medial prefrontal cortex neurons from young Alzheimer's disease mice compared to controls. Additionally, acute exposure to Aβ42 potentiated medial prefrontal cortex neuronal hyperactivity in young Alzheimer's disease mice but had no effects on controls. These findings indicate that the hyperactivity of medial prefrontal cortex pyramidal neurons at early-stage Alzheimer's disease is induced by an abnormal increase in presynaptic glutamate release and postsynaptic NMDA receptor activity, which initiates neuronal Ca2+ dyshomeostasis. Additionally, because accumulated Aβ forms unconventional but functional Ca2+ channels in medial prefrontal cortex neurons in the late stage of Alzheimer's disease, our study also suggests an exacerbated Ca2+ dyshomeostasis in medial prefrontal cortex pyramidal neurons following overactivation of such VGCCs.

To study the effect of ER flux with buffer on the neuronal calcium

Calcium signaling is decisive for cellular functions. This calcium random walk stipulates neuronal functions. Calcium concentration could provoke gene transcription, apoptosis, neuronal plasticity, etc. A malformation in calcium could change the neuron's intracellular behavior. Calcium concentration balancing is a complex cellular mechanism. This occurrence can be handled with the Caputo fractional reaction-diffusion equation. In this mathematical modeling, we have included the STIM-Orai mechanism and Endoplasmic Reticulum (ER) flux, Inositol Triphosphate Receptor (IPR), SERCA, plasma membrane flux, voltage-gated calcium entry, and different buffer interactions. A hybrid integral transform and Green's function approach were taken to solve the initial boundary problem. A closed-form solution of a Mittag-Leffler family function plotted using MATLAB software. Different parameters impact changes in the spatiotemporal behavior of the calcium concentration. Specific roles of organelles involved in Alzheimer's disease-affected neurons are computed. Ethylene glycol tetraacetic acid (EGTA), 1,2-bis(o-aminophenoxy)ethane N,N,N,N-tetraacetic acid (BAPTA), and S100B protein effects are also observed. In all simulations, we can say S100B and the STIM-Orai effect cannot be neglected. This model lights up the different approaches for calcium signaling pathway simulation. As a consequence, we determine that a generalized reaction-diffusion approach is a better fit realistic model.

Redox states in the endoplasmic reticulum directly regulate the activity of calcium channel, inositol 1,4,5-trisphosphate receptors

Inositol 1,4,5-trisphosphate receptors (IP3Rs) are one of the two types of tetrameric ion channels that release calcium ion (Ca2+) from the endoplasmic reticulum (ER) into the cytosol. Ca2+ released via IP3Rs is a fundamental second messenger for numerous cell functions. Disturbances in the intracellular redox environment resulting from various diseases and aging interfere with proper calcium signaling, however, the details are unclear. Here, we elucidated the regulatory mechanisms of IP3Rs by protein disulfide isomerase family proteins localized in the ER by focusing on four cysteine residues residing in the ER lumen of IP3Rs. First, we revealed that two of the cysteine residues are essential for functional tetramer formation of IP3Rs. Two other cysteine residues, on the contrary, were revealed to be involved in the regulation of IP3Rs activity; its oxidation by ERp46 and the reduction by ERdj5 caused the activation and the inactivation of IP3Rs activity, respectively. We previously reported that ERdj5 can activate the sarco/endoplasmic reticulum Ca2+-ATPase isoform 2b (SERCA2b) using its reducing activity [Ushioda et al., Proc. Natl. Acad. Sci. U.S.A. 113, E6055-E6063 (2016)]. Thus, we here established that ERdj5 exerts the reciprocal regulatory function for IP3Rs and SERCA2b by sensing the ER luminal Ca2+ concentration, which contributes to the calcium homeostasis in the ER.

Stress granules sequester Alzheimer's disease-associated gene transcripts and regulate disease-related neuronal proteostasis

Environmental and physiological stresses can accelerate Alzheimer's disease (AD) pathogenesis. Under stress, a cytoplasmic membraneless structure termed a stress granule (SG) is formed and is associated with various neurodegenerative disorders, including AD. SGs contain translationally arrested mRNAs, suggesting that impaired RNA metabolism in neurons causes AD progression; however, the underlying mechanism remains unclear. Here, we identified numerous mRNAs and long non-coding RNAs that are directly targeted by the SG core proteins G3BP1 and G3BP2. They redundantly target RNAs before and after stress conditions. We further identified RNAs within SGs, wherein AD-associated gene transcripts accumulated, suggesting that SGs can directly regulate AD development. Furthermore, gene-network analysis revealed a possible link between the sequestration of RNAs by SGs and the impairment of protein neurohomeostasis in AD brains. Together, our study provides a comprehensive RNA regulatory mechanism involving SGs, which could be targeted therapeutically to slow AD progression mediated by SGs.

The Mitochondrial Permeability Transition Pore-Current Knowledge of Its Structure, Function, and Regulation, and Optimized Methods for Evaluating Its Functional State

The mitochondrial permeability transition pore (MPTP) is a calcium-dependent, ion non-selective membrane pore with a wide range of functions. Although the MPTP has been studied for more than 50 years, its molecular structure remains unclear. Short-term (reversible) opening of the MPTP protects cells from oxidative damage and enables the efflux of Ca2+ ions from the mitochondrial matrix and cell signaling. However, long-term (irreversible) opening induces processes leading to cell death. Ca2+ ions, reactive oxygen species, and changes in mitochondrial membrane potential regulate pore opening. The sensitivity of the pore to Ca2+ ions changes as an organism ages, and MPTP opening plays a key role in the pathogenesis of many diseases. Most studies of the MPTP have focused on elucidating its molecular structure. However, understanding the mechanisms that will inhibit the MPTP may improve the treatment of diseases associated with its opening. To evaluate the functional state of the MPTP and its inhibitors, it is therefore necessary to use appropriate methods that provide reproducible results across laboratories. This review summarizes our current knowledge of the function and regulation of the MPTP. The latter part of the review introduces two optimized methods for evaluating the functional state of the pore under standardized conditions.

Cordyceps cicadae NTTU 868 Mycelia Fermented with Deep Ocean Water Minerals Prevents D-Galactose-Induced Memory Deficits by Inhibiting Oxidative Inflammatory Factors and Aging-Related Risk Factors

Cordyceps cicadae, a medicinal fungus that is abundant in bioactive compounds such as N6-(2-hydroxyethyl)-adenosine (HEA) and polysaccharides, possesses remarkable anti-inflammatory, antioxidant, and nerve damage recovery properties. Deep ocean water (DOW) contains minerals that can be absorbed and transformed into organic forms by fungi fermentation. Recent studies have shown that culturing C. cicadae in DOW can enhance its therapeutic benefits by increasing the levels of bioactive compounds and minerals' bioavailibility. In this study, we investigated the effects of DOW-cultured C. cicadae (DCC) on brain damage and memory impairment induced by D-galactose in rats. Our results indicate that DCC and its metabolite HEA can improve memory ability and exhibit potent antioxidant activity and free radical scavenging in D-galactose-induced aging rats (p < 0.05). Additionally, DCC can mitigate the expression of inflammatory factors, such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS), thereby preventing brain aging. Furthermore, DCC showed a significant decrease in the expression of the aging-related proteins glial fibrillary acidic protein (GFAP) and presenilin 1 (PS1). By reducing brain oxidation and aging-related factors, DOW-cultured C. cicadae demonstrate enhanced anti-inflammatory, antioxidant, and neuroprotective effects, making it a promising therapeutic agent for preventing and treating age-related brain damage and cognitive impairment.

Acai Berry (Euterpe sp.) Extracts Are Neuroprotective against L-Glutamate-Induced Toxicity by Limiting Mitochondrial Dysfunction and Cellular Redox Stress

Aberrant accumulation of the neurotransmitter L-glutamate (L-Glu) has been implicated as a mechanism of neurodegeneration, and the release of L-Glu after stroke onset leads to a toxicity cascade that results in neuronal death. The acai berry (Euterpe oleracea) is a potential dietary nutraceutical. The aim of this research was to investigate the neuroprotective effects of acai berry aqueous and ethanolic extracts to reduce the neurotoxicity to neuronal cells triggered by L-Glu application. L-Glu and acai berry effects on cell viability were quantified using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays, and effects on cellular bioenergetics were assessed via quantitation of the levels of cellular ATP, mitochondrial membrane potential (MMP), and production of reactive oxygen species (ROS) in neuroblastoma cells. Cell viability was also evaluated in human cortical neuronal progenitor cell culture after L-Glu or/and acai berry application. In isolated cells, activated currents using patch-clamping were employed to determine whether L-Glu neurotoxicity was mediated by ionotropic L-Glu-receptors (iGluRs). L-Glu caused a significant reduction in cell viability, ATP, and MMP levels and increased ROS production. The co-application of both acai berry extracts with L-Glu provided neuroprotection against L-Glu with sustained cell viability, decreased LDH production, restored ATP and MMP levels, and reduced ROS levels. Whole-cell patch-clamp recordings showed that L-Glu toxicity is not mediated by the activation of iGluRs in neuroblastoma cells. Fractionation and analysis of acai berry extracts with liquid chromatography-mass spectrometry identified several phytochemical antioxidants that may have provided neuroprotective effects. In summary, the acai berry contains nutraceuticals with antioxidant activity that may be a beneficial dietary component to limit pathological deficits triggered by excessive L-Glu accumulations.

MicroRNA-593-5p contributes to cell death following exposure to 1-methyl-4-phenylpyridinium (MPP+) by targeting PTEN-induced putative kinase 1 (PINK1)

Neurodegenerative diseases are characterized by a decline in neuronal function and structure, leading to neuronal death. Understanding the molecular mechanisms of neuronal death is crucial for developing therapeutics. MicroRNAs (miRs) are small non-coding RNAs that regulate gene expression by degrading target mRNAs or inhibiting translation. MiR dysregulation has been linked to many neurodegenerative diseases, but the underlying mechanisms are not well understood. As mitochondrial dysfunction is one of the common molecular mechanisms leading to neuronal death in many neurodegenerative diseases, here we studied miRs that modulate neuronal death caused by 1-methyl-4-phenylpyridinium (MPP+), an inhibitor of complex I in mitochondria. We identified miR-593-5p, levels of which were increased in SH-SY5Y human neuronal cells, after exposure to MPP⁺. We found that intracellular Ca²⁺, but not of reactive oxygen species (ROS), mediated this miR-593-5p increase. Furthermore, we found the increase in miR-593-5p was due to enhanced stability, not increased transcription or miR processing. Importantly, we show the increase in miR-593-5p contributed to MPP⁺-induced cell death. Our data revealed that miR-593-5p inhibits a signaling pathway involving PTEN-induced putative kinase 1 (PINK1) and Parkin, two proteins responsible for the removal of damaged mitochondria from cells, by targeting the coding sequence of PINK1 mRNA. Our findings suggest that miR-593-5p contributes to neuronal death resulting from MPP⁺ toxicity, in part, by impeding the PINK1/Parkin-mediated pathway that facilitates the clearance of damaged mitochondria. Taken together, our observations highlight the potential significance of inhibiting miR-593-5p as a therapeutic approach for neurodegenerative diseases.

TRPM2 Channel Inhibition Attenuates Amyloid β42-Induced Apoptosis and Oxidative Stress in the Hippocampus of Mice

Alzheimer's disease (AD) is characterized by the increase of hippocampal Ca2+ influx-induced apoptosis and mitochondrial oxidative stress (OS). The OS is a stimulator of TRPM2, although N-(p-amylcinnamoyl)anthranilic acid (ACA), 2-aminoethyl diphenylborinate (2/APB), and glutathione (GSH) are non-specific antagonists of TRPM2. In the present study, we investigated the protective roles of GSH and TRPM2 antagonist treatments on the amyloid β42 peptide (Aβ)-caused oxidative neurotoxicity and apoptosis in the hippocampus of mice with AD model. After the isolation of hippocampal neurons from the newborn mice, they were divided into five incubation groups as follows: control, ACA, Aβ, Aβ+ACA, and Aβ+GSH. The levels of apoptosis, hippocampus death, cytosolic ROS, cytosolic Zn2+, mitochondrial ROS, caspase-3, caspase-9, lipid peroxidation, and cytosolic Ca2+ were increased in the primary hippocampus cultures by treatments of Aβ, although their levels were decreased in the neurons by the treatments of GSH, PARP-1 inhibitors (PJ34 and DPQ), and TRPM2 blockers (ACA and 2/APB). The Aβ-induced decreases of cell viability, cytosolic GSH, reduced GSH, and GSH peroxidase levels were also increased in the groups of Aβ+ACA and Aβ+GSH by the treatments of ACA and GSH. However, the Aβ-caused changes were not observed in the hippocampus of TRPM2-knockout mice. In conclusion, the present data demonstrate that maintaining the activation of TRPM2 is not only important for the quenching OS and neurotoxicity in the hippocampal neurons of mice with experimental AD but also equally critical to the modulation of Aβ-induced apoptosis. The possible positive effects of GSH and TRPM2 antagonist treatments on the amyloid-beta (Aβ)-induced oxidative toxicity in the hippocampus of mice. The ADP-ribose (ADPR) is produced via the stimulation of PARP-1 in the nucleus of neurons. The NUT9 in the C terminus of TRPM2 channel acts as a key role for the activation of TRPM2. The antagonists of TRPM2 are glutathione (GSH), ACA, and 2/APB in the hippocampus. The Aβ incubation-mediated TRPM2 stimulation increases the concentration of cytosolic-free Ca2+ and Zn2+ in the hippocampus. In turn, the increased concentration causes the increase of mitochondrial membrane potential (ΔΨm), which causes the excessive generations of mitochondria ROS and the decrease of cytosolic GSH and GSH peroxidase (GSH-Px). The ROS production and GSH depletion are two main causes in the neurobiology of Alzheimer's disease. However, the effect of Aβ was not shown in the hippocampus of TRPM2-knockout mice. The Aβ and TRPM2 stimulation-caused overload Ca2+ entry cause apoptosis and cell death via the activations of caspase-3 (Casp/3) and caspase-9 (Casp/9) in the hippocampus. The actions of Aβ-induced oxidative toxicity were modulated in the primary hippocampus by the incubations of ACA, GSH, 2/APB, and PARP-1 inhibitors (PJ34 and DPQ). (↑) Increase. (↓) Decrease.

Exposure to 6-PPD Quinone at Environmentally Relevant Concentrations Causes Abnormal Locomotion Behaviors and Neurodegeneration in Caenorhabditis elegans

6-PPD quinone (6-PPDQ) can be transformed from 6-PPD through ozonation. Nevertheless, the potential neurotoxicity of 6-PPDQ after long-term exposure and the underlying mechanism are largely unclear. In Caenorhabditis elegans, we here observed that 0.1-10 μg/L of 6-PPDQ caused several forms of abnormal locomotion behaviors. Meanwhile, the neurodegeneration of D-type motor neurons was observed in 10 μg/L of 6-PPDQ-exposed nematodes. The observed neurodegeneration was associated with the activation of the Ca²⁺ channel DEG-3-mediated signaling cascade. In this signaling cascade, expressions of deg-3, unc-68, itr-1, crt-1, clp-1, and tra-3 were increased by 10 μg/L of 6-PPDQ. Moreover, among genes encoding neuronal signals required for the control of stress response, expressions of jnk-1 and dbl-1 were decreased by 0.1-10 μg/L of 6-PPDQ, and expressions of daf-7 and glb-10 were decreased by 10 μg/L of 6-PPDQ. RNAi of jnk-1, dbl-1, daf-7, and glb-10 resulted in the susceptibility to 6-PPDQ toxicity in decreasing locomotory ability and in inducing neurodegeneration, suggesting that JNK-1, DBL-1, DAF-7, and GLB-10 were also required for the induction of 6-PPDQ neurotoxicity. Molecular docking analysis further demonstrated the binding potential of 6-PPDQ to DEG-3, JNK-1, DBL-1, DAF-7, and GLB-10. Together, our data suggested the exposure risk of 6-PPDQ at environmentally relevant concentrations in causing neurotoxicity in organisms.

Molecular Mechanisms and Pathophysiological Significance of Eryptosis

Despite lacking the central apoptotic machinery, senescent or damaged RBCs can undergo an unusual apoptosis-like cell death, termed eryptosis. This premature death can be caused by, or a symptom of, a wide range of diseases. However, various adverse conditions, xenobiotics, and endogenous mediators have also been recognized as triggers and inhibitors of eryptosis. Eukaryotic RBCs are unique among their cell membrane distribution of phospholipids. The change in the RBC membrane composition of the outer leaflet occurs in a variety of diseases, including sickle cell disease, renal diseases, leukemia, Parkinson’s disease, and diabetes. Eryptotic erythrocytes exhibit various morphological alterations such as shrinkage, swelling, and increased granulation. Biochemical changes include cytosolic Ca2+ increase, oxidative stress, stimulation of caspases, metabolic exhaustion, and ceramide accumulation. Eryptosis is an effective mechanism for the elimination of dysfunctional erythrocytes due to senescence, infection, or injury to prevent hemolysis. Nevertheless, excessive eryptosis is associated with multiple pathologies, most notably anemia, abnormal microcirculation, and prothrombotic risk; all of which contribute to the pathogenesis of several diseases. In this review, we provide an overview of the molecular mechanisms, physiological and pathophysiological relevance of eryptosis, as well as the potential role of natural and synthetic compounds in modulating RBC survival and death.

Taking Charge: Metal Ions Accelerate Amyloid Aggregation in Sequence Variants of α-Synuclein

Αlpha-synuclein (αS) is an intrinsically disordered protein which exhibits a high degree of conformational heterogeneity. In vivo, αS experiences various environments which cause adaptation of its structural ensemble. Divalent metal ions are prominent in synaptic terminals where αS is located and are thought to bind to the αS C-terminal region. Herein, we used native nanoelectrospray ionization ion mobility-mass spectrometry to investigate changes in the charge state distribution and collision cross sections of wild-type N-terminally acetylated (NTA) αS, along with a deletion variant (ΔΔNTA) which inhibits amyloid formation and a C-terminal truncated variant (119NTA) which increases the rate of amyloid formation. We also examine the effect of the addition of divalent metal ions, Ca²⁺, Mn²⁺, and Zn²⁺, and correlate the conformational properties of the αS monomer with the ability to aggregate into amyloid, measured using Thioflavin T fluorescence and negative stain transmission electron microscopy. We find a correlation between the population of species with a low collision cross section and accelerated amyloid assembly kinetics, with the presence of metal ions resulting in protein compaction and causing ΔΔ to regain its ability to form an amyloid. The results portray how the αS conformational ensemble is governed by specific intramolecular interactions that influence its amyloidogenic behavior.

The interactions of amyloid β aggregates with phospholipid membranes and the implications for neurodegeneration

Misfolding, aggregation and accumulation of Amyloid-β peptides (Aβ) in neuronal tissue and extracellular matrix are hallmark features of Alzheimer's disease (AD) pathology. Soluble Aβ oligomers are involved in neuronal toxicity by interacting with the lipid membrane, compromising its integrity, and affecting the function of receptors. These facts indicate that the interaction between Aβ oligomers and cell membranes may be one of the central molecular level factors responsible for the onset of neurodegeneration. The present review provides a structural understanding of Aβ neurotoxicity via membrane interactions and contributes to understanding early events in Alzheimer's disease.

Hallmarks of neurodegenerative diseases

Decades of research have identified genetic factors and biochemical pathways involved in neurodegenerative diseases (NDDs). We present evidence for the following eight hallmarks of NDD: pathological protein aggregation, synaptic and neuronal network dysfunction, aberrant proteostasis, cytoskeletal abnormalities, altered energy homeostasis, DNA and RNA defects, inflammation, and neuronal cell death. We describe the hallmarks, their biomarkers, and their interactions as a framework to study NDDs using a holistic approach. The framework can serve as a basis for defining pathogenic mechanisms, categorizing different NDDs based on their primary hallmarks, stratifying patients within a specific NDD, and designing multi-targeted, personalized therapies to effectively halt NDDs.