α-Synuclein in Parkinson's disease

Targeting the glymphatic system to promote α-synuclein clearance: a novel therapeutic strategy for Parkinson's disease

The excessive buildup of neurotoxic α-synuclein plays a pivotal role in the pathogenesis of Parkinson's disease, highlighting the urgent need for innovative therapeutic strategies to promote α-synuclein clearance, particularly given the current lack of disease-modifying treatments. The glymphatic system, a recently identified perivascular fluid transport network, is crucial for clearing neurotoxic proteins. This review aims to synthesize current knowledge on the role of the glymphatic system in α-synuclein clearance and its implications for the pathology of Parkinson's disease while emphasizing potential therapeutic strategies and areas for future research. The review begins with an overview of the glymphatic system and details its anatomical structure and physiological functions that facilitate cerebrospinal fluid circulation and waste clearance. It summarizes emerging evidence from neuroimaging and experimental studies that highlight the close correlation between the glymphatic system and clinical symptom severity in patients with Parkinson's disease, as well as the effect of glymphatic dysfunction on α-synuclein accumulation in Parkinson's disease models. Subsequently, the review summarizes the mechanisms of glymphatic system impairment in Parkinson's disease, including sleep disturbances, aquaporin-4 impairment, and mitochondrial dysfunction, all of which diminish glymphatic system efficiency. This creates a vicious cycle that exacerbates α-synuclein accumulation and worsens Parkinson's disease. The therapeutic perspectives section outlines strategies for enhancing glymphatic activity, such as improving sleep quality and pharmacologically targeting aquaporin-4 or its subcellular localization. Promising interventions include deep brain stimulation, melatonin supplementation, γ-aminobutyric acid modulation, and non-invasive methods (such as exercise and bright-light therapy), multisensory γ stimulation, and ultrasound therapy. Moreover, identifying neuroimaging biomarkers to assess glymphatic flow as an indicator of α-synuclein burden could refine Parkinson's disease diagnosis and track disease progression. In conclusion, the review highlights the critical role of the glymphatic system in α-synuclein clearance and its potential as a therapeutic target in Parkinson's disease. It advocates for further research to elucidate the specific mechanisms by which the glymphatic system clears misfolded α-synuclein and the development of imaging biomarkers to monitor glymphatic activity in patients with Parkinson's disease. Findings from this review suggest that enhancing glymphatic clearance is a promising strategy for reducing α-synuclein deposits and mitigating the progression of Parkinson's disease.

In silico screening of peptide inhibitors targeting α-synuclein for Parkinson's disease

Parkinson's disease affects cognitive, motor, and autonomic functions due to nervous system degeneration. Though no cure exists, medications and therapies can help alleviate symptoms, but their effectiveness diminishes as the disease progresses, ultimately increasing the need for alternative treatments. α-Synuclein has long been one of the main targets in addressing Parkinson's through drug design studies, but no drugs are yet approved against α-Synuclein aggregation. Therefore, this study aims to develop potential inhibitors of fibrillization by screening thousands of peptides in terms of their binding abilities via Molecular Docking and Molecular Dynamics simulations. Our results show that peptides with Lysine and Arginine at terminal groups result in higher binding affinities to the C-terminal domain. Among the heptapeptides examined, RWRRKRL shows the highest binding free energy to the protein while KKRHKWR exhibits superior stabilizing effect, interacting with both N- and C-terminal regions of α-Synuclein. The inhibitory potential of peptides on the fibrillar structure of protein varies with concentration, and RWRRKRL at 1:3 protein-peptide monomer ratio shows promise as an inhibitor by reducing the internal H-bonds of the protein and increasing RMSD values. These results reveal that short-chain peptides can be designed against α-Synuclein oligomerization offering a potential therapeutic approach for preventing Parkinson's.

Proinflammatory and GABA eating bacteria in Parkinson's disease gut microbiome from a meta-analysis prospective

Parkinson's disease (PD) is the second most common neurodegenerative disorder, characterized by motor dysfunction coupled with gastrointestinal disturbances. Recent studies implicate the gut microbiome with the development of PD, yet pinpointing the exact microbial players is still to be determined. This meta-analysis is the first to consolidate five homogenous case-control studies, covering the same variable regions of the 16S rRNA of 1007 fecal samples. Utilizing our unified pipeline, we identified several key players potentially contributing to PD. Our findings reveal higher microbial diversity characterized by elevated levels GABA consuming species particularly Evtepia gabavorous, contributing to neuronal excitability. We also report the abundance of the proinflammatory Klebsiella variicola and the H2S-producing Streptococcus anginosus bacteria, potentially promoting α-synuclein accumulation in the brain. This comprehensive analysis highlights the potential of gut microbiota as a biomarker and a therapeutic strategy to mitigate the progression of PD, possibly facilitating diagnosis and enhancing patient outcomes.

Gut neuropeptide involvement in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disorder affecting over 10 million people. A key pathological feature of PD is the accumulation of misfolded α-synuclein (aSyn) protein in the substantia nigra pars compacta. Aggregation of aSyn can form Lewy bodies that contribute to dopaminergic neuron degeneration and motor symptoms, such as tremor, rigidity, and bradykinesia. Beyond the central nervous system, aSyn aggregates have been detected in the gastrointestinal (GI) tract, suggesting a link between peripheral aSyn and nonmotor PD symptoms. GI symptoms, often preceding motor symptoms by up to 20 years, highlight the bidirectional communication between the central nervous system and the enteric nervous system (gut-brain axis) in PD. Although microbiome alterations and intestinal inflammation have been associated with PD, functional impacts on gut-brain signaling or aSyn aggregation remain unclear. Intestinal neuropeptides are key modulators of gut-brain communication, alter immune response to pathogens and environmental toxins, and may contribute to the function of the luminal gut barrier. Dysregulation of gut neuropeptide signaling, including vasoactive intestinal peptide, neuropeptide Y, calcitonin gene-related peptide, ghrelin, cholecystokinin, glucagon-like peptide 1, and substance P, have been associated with pathologic effects of PD in animal models. Despite their potential role in pathogenesis and disease modulation, gut neuropeptide roles in PD are underexplored. This article reviews current knowledge surrounding microbial metabolite and immune influences on gut neuropeptide signaling, aSyn aggregation in the enteric nervous system, and downstream neuroimmune pathway alterations within the context of PD and its mouse models.

Advancing Parkinson's diagnosis: seed amplification assay for α-synuclein detection in minimally invasive samples

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by tremor, rigidity, and bradykinesia, beginning with early loss of dopaminergic neurons in the ventrolateral substantia nigra and advancing to broader neurodegeneration in the midbrain. The clinical heterogeneity of PD and the lack of specific diagnostic tests present significant challenges, highlighting the need for reliable biomarkers for early diagnosis. Alpha-synuclein (α-Syn), a protein aggregating into Lewy bodies and neurites in PD patients, has emerged as a key biomarker due to its central role in PD pathophysiology and potential to reflect pathological processes. Additionally, α-Syn allows earlier differentiation between PD and other neurodegenerative disorders with similar symptoms. Currently, detection of α-Syn pathology in post-mortem brain tissue remains the primary means of achieving a conclusive diagnosis, often revealing significant misdiagnoses. Seed amplification assay (SAA), initially developed for prion diseases, has been adapted to detect α-Syn aggregates in cerebrospinal fluid, showing promise for early diagnosis. Recent studies have demonstrated that SAA can also detect α-Syn aggregates in peripheral samples collected via minimally invasive procedures, such as skin, olfactory mucosa, saliva, and blood. However, the lack of standardized protocols limits clinical application. Standardizing protocols is essential to improve assay reliability and enable accurate patient identification for emerging therapies. This review examines studies on SAA for detecting α-Syn aggregates in minimally invasive samples, focusing on sample collection, processing, and reaction conditions.

Unveiling the role of Na⁺/K⁺-ATPase pump: neurodegenerative mechanisms and therapeutic horizons

Sodium and potassium-activated adenosine 5'-triphosphatase (Na+/K+-ATPase) is a pivotal plasma membrane enzyme involved in neuronal activity and cellular homeostasis. The dysregulation of these enzymes has been implicated in a spectrum of neurodegenerative disorders like Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and neurodevelopmental disorders including autism spectrum disorder (ASD), psychiatric disorders such as schizophrenia, and neurological problems like epilepsy. A hallmark of these disorders is the gradual loss of neuronal integrity and function, often exacerbated by protein accumulation within brain cells. This review delves into the multifaceted role of Na+/K+-ATPase dysfunction in driving oxidative stress, excitotoxicity, and neuroinflammation, contributing to synaptic and neuronal damage. Emerging therapeutic strategies, such as gene therapy and developing isoform-specific enzyme modulators, offer promising avenues for targeted interventions. Furthermore, this review highlights innovative research directions, including the role of Na⁺/K⁺-ATPase in synaptic plasticity, the identification of endogenous regulators, and its contribution to neuroinflammatory pathways. Personalized medicine and advanced gene-editing technologies are positioned as transformative tools for crafting safer and more precise therapies tailored to individual patients. This comprehensive exploration underscores the enzyme's therapeutic potential and sets the stage for developing novel targeted strategies to mitigate the burden of Na⁺/K⁺-ATPase-linked neurological disorders.

Computer-Aided Drug Discovery for Undruggable Targets

Undruggable targets are those of therapeutical significance but challenging for conventional drug design approaches. Such targets often exhibit unique features, including highly dynamic structures, a lack of well-defined ligand-binding pockets, the presence of highly conserved active sites, and functional modulation by protein-protein interactions. Recent advances in computational simulations and artificial intelligence have revolutionized the drug design landscape, giving rise to innovative strategies for overcoming these obstacles. In this review, we highlight the latest progress in computational approaches for drug design against undruggable targets, present several successful case studies, and discuss remaining challenges and future directions. Special emphasis is placed on four primary target categories: intrinsically disordered proteins, protein allosteric regulation, protein-protein interactions, and protein degradation, along with discussion of emerging target types. We also examine how AI-driven methodologies have transformed the field, from applications in protein-ligand complex structure prediction and virtual screening to de novo ligand generation for undruggable targets. Integration of computational methods with experimental techniques is expected to bring further breakthroughs to overcome the hurdles of undruggable targets. As the field continues to evolve, these advancements hold great promise to expand the druggable space, offering new therapeutic opportunities for previously untreatable diseases.

Alpha-Synuclein drives NURR1 and NLRP3 Inflammasome dysregulation in Parkinson's disease: From pathogenesis to potential therapeutic strategies

Parkinson's disease (PD), a progressive neurodegenerative disorder, is characterized by the loss of dopaminergic neurons and pathological aggregation of α-synuclein (α-Syn). Emerging evidence highlights the interplay between genetic susceptibility, neuroinflammation, and transcriptional dysregulation in driving PD pathogenesis. This review brings together the latest information on three important players: α-Syn, the transcription factor Orphan nuclear receptor (NURR1), and the NOD-like receptor 3 (NLRP3) inflammasome. Pathogenic α-syn aggregates cause damage to neurons by disrupting mitochondria and lysosomes and spreading in a way similar to prion proteins. They also turn on the NLRP3 inflammasome, which is a key player in neuroinflammation. NLRP3-driven release of pro-inflammatory cytokines exacerbates neurodegeneration and creates a self-sustaining inflammatory milieu. Meanwhile, reduced NURR1 activity, a pivotal modulator of dopaminergic neuron survival and development, exposes neurons to oxidative stress, neuroinflammation, and α-Syn toxicity, hence exacerbating disease progression. So, targeting this trio exhibits transformative potential against PD pathogenesis.

UPS10 inhibits the degradation of α-synuclein, a pathogenic factor associated with Parkinson's disease, by inhibiting chaperone-mediated autophagy

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by loss of dopaminergic neurons, particularly in the substantia nigra of the brain. α-Synuclein is a major causative factor in both familial and sporadic forms of PD, and its protein aggregates play critical roles in neuronal cell death and PD pathogenesis. This study explored the role of ubiquitin-specific protease 10 (USP10) in the regulation of α-synuclein in neuronal cells. Knockdown of USP10 (USP10-KD) in SH-SY5Y neuronal cells led to a reduction in α-synuclein levels, which was reversed by inhibiting chaperone-mediated autophagy (CMA) through LAMP2A depletion, a protein essential for CMA. A novel CMA reporter with a specific CMA degradation motif further demonstrated that USP10-KD activated CMA in neuronal cells. In addition, USP10 overexpression increased the levels of both wild-type and five PD-associated α-synuclein mutants, whereas a deubiquitinase-deficient USP10 mutant did not increase α-synuclein levels. This study provides new insights into the mechanisms that regulate α-synuclein proteostasis and highlights USP10 as a promising drug target for PD.

Mechanism of flavonoid myricetin modulated aggregation in α-Synuclein and its familial mutants E46K and A30P

Inhibiting the aggregation of α-Synuclein (α-Syn) and its familial mutants E46K and A30P has emerged as one of the effective therapeutic strategies against Parkinson's disease (PD). The inhibition and modulation of α-Syn/E46K/A30P fibrillation as well as disaggregation of their pre-formed fibrils by a natural flavonoid myricetin (Myr) is studied. The binding of Myr with α-Syn and its mutants with the affinity ranging 104-105 M-1. The isothermal titration calorimetry (ITC) results indicate the involvement of hydrogen binding/ionic and hydrophobic interactions in the binding process. The aggregation kinetics studies demonstrate that Myr inhibits aggregation of α-Syn/E46K/A30P in a concentration dependent manner. Seeding experiments demonstrate that the protein aggregates formed in the presence of Myr do not further instigates aggregation in healthy proteins. Myr also modulates the aggregation process of protein when added after the onset of aggregation. Circular dichroism (CD) show that Myr delays the structural transition of native α-Syn/E46K/A30P into β-sheets rich fibrillar structures. Myr also disassemble the pre-formed fibrillar structures of α-Syn its mutants. These outcomes offer profound insight into the modulatory mechanism of aggregation of α-Syn, E46K and A30P by Myr, thereby suggesting its potential role in designing combination therapies against protein fibrillation related disorders.

Morin Interacts with α-Synuclein and Retards Its Fibrillation

α-Synuclein is a small (14 kDa) intrinsically disordered water-soluble protein, and its unwanted aggregation and fibrillation are believed to play a critical role in the pathogenesis of Parkinson's disease. Our current investigation uniquely utilized intrinsic tyrosine fluorescence of α-synuclein and showed that morin hydrate (MOR), a polyhydroxyflavonol, in aqueous solution formed a 1:1 complex with a sub-micromolar range of binding affinity and stabilized the protein structure at an ambient solution condition. Steady-state fluorescence of the protein, in the presence of MOR, was quenched; however, the fluorescence lifetime (∼1.28 ns) was not significantly perturbed; it indicated formation of ground-state association of the flavonol with the protein. The estimated binding constant was ∼4.5 × 104 M-1 and indicated a weak binding interaction at room temperature (∼25 °C). However, the presence of the MOR stabilizes the protein residues in their α-helical space; circular dichroism spectroscopic analysis revealed reduction in disordered content and an elevation of the protein conformation more toward the folded structure. A tandem use of atomic force microscopy and thioflavin T-based fluorescence measurement of the incubated samples in the presence of flavonol showed retardation of aggregation and associated fibrillation. Computational analysis also showed that the presence of the molecule rendered α-synuclein to be more compacted, and a greater number of amino acid residues were found to be in α-helical conformational space. Residues Val40, Glu126, Gln134, and Tyr136 were involved mainly in hydrogen bond interaction, and residues Gly41, Lys43, and Asp135 enhanced conformational stability via water bridges. The results confirmed that the weak but ample interaction of morin hydrate provided structural stability to otherwise highly fluctuating α-synuclein via hydrophobic and hydrogen bond interaction. It caused retardation in the processes of hydrophobic zipping (among the amyloidogenic regions), which is believed to be a key event in the processes of cross-β-sheet-rich amyloid fibril formation, the event that is highly implicated in the pathology of Parkinson and other neurodegenerative diseases.

Heterotypic Droplet Formation by Pro-Inflammatory S100A9 and Neurodegenerative Disease-Related α-Synuclein

Liquid-liquid phase separation of proteins and nucleic acids is a rapidly emerging field of study, aimed at understanding the process of biomolecular condensate formation. Recently, it has been discovered that different neurodegenerative disease-related proteins, such as α-synuclein and amyloid-β are capable of forming heterotypic droplets. Other reports have also shown non-LLPS cross-interactions between various amyloidogenic proteins and the resulting influence on their amyloid fibril formation. This includes the new discovery of pro-inflammatory S100A9 affecting the aggregation of both amyloid-β, as well as α-synuclein. In this study, we explore the formation of heterotypic droplets by S100A9 and α-synuclein. We show that their mixture is capable of assembling into both homotypic and heterotypic condensates and that this cross-interaction alters the aggregation mechanism of α-synuclein. These results provide insight into the influence of S100A9 on the process of neurodegenerative disease-related protein LLPS and aggregation.

Probabilistic Mapping and Automated Segmentation of Human Brainstem White Matter Bundles

Brainstem white matter bundles are essential conduits for neural signaling involved in modulation of vital functions ranging from homeostasis to human consciousness. Their architecture forms the anatomic basis for brainstem connectomics, subcortical mesoscale circuit models, and deep brain navigation tools. However, their small size and complex morphology compared to cerebral white matter structures makes mapping and segmentation challenging in neuroimaging. This results in a near absence of automated brainstem white matter tracing methods. We leverage diffusion MRI tractography to create BrainStem Bundle Tool (BSBT), which segments eight key white matter bundles in the rostral brainstem. BSBT performs automated segmentation on a custom probabilistic fiber map generated from tractography with a convolutional neural network architecture tailored for detection of small structures. We demonstrate BSBTs robustness across diffusion MRI acquisition protocols through validation on healthy subject in vivo scans and ex vivo scans of brain specimens with corresponding histology. Using BSBT, we reveal distinct brainstem white matter bundle alterations in Alzheimer's disease, Parkinson's disease, and acute traumatic brain injury cohorts through tract-based analysis and classification tasks. Finally, we provide proof-of-principle evidence supporting the prognostic utility of BSBT in a longitudinal analysis of coma recovery. BSBT creates opportunities to automatically map brainstem white matter in large imaging cohorts and investigate its role in a broad spectrum of neurological disorders.

The modifying effect of mutant LRRK2 on mutant GBA1-associated Parkinson disease

Parkinson disease (PD) is the second most common neurodegenerative disease. While most cases are sporadic, in ~ 5%-10% of PD patients the disease is caused by mutations in several genes, among them GBA1 (glucocerebrosidase beta 1) and LRRK2 (leucine-rich repeat kinase 2), both prevalent among the Ashkenazi Jewish population. LRRK2-associated PD tends to be milder than GBA1-associated PD. Several recent clinical studies have suggested that carriers of both GBA1 and LRRK2 mutations develop milder PD compared to that observed among GBA1 carriers. These findings strongly suggested an interplay between the two genes in the development and progression of PD. In the present study Drosophila was employed as a model to investigate the impact of mutations in the LRRK2 gene on mutant GBA1-associated PD. Our results strongly indicated that flies expressing both mutant genes exhibited milder parkinsonian signs compared to the disease developed in flies expressing only a GBA1 mutation. This was corroborated by a decrease in the ER stress response, increase in the number of dopaminergic cells, elevated levels of tyrosine hydroxylase, reduced neuroinflammation, improved locomotion and extended survival. Furthermore, a significant decrease in the steady-state levels of mutant GBA1-encoded GCase was observed in the presence of mutant LRRK2, strongly implying a role for mutant LRRK2 in degradation of mutant GCase.

Mechanistic insights into Alpha-Synuclein binding to P2RX7: A molecular dynamic and docking study

Alpha-synucleinopathies, characterized by extracellular alpha-synuclein (αSyn or SNCA) accumulation and aggregation, have been linked to neurological disorders including Parkinson's disease and multiple system atrophy. P2RX7 is a non-selective cationic transmembrane purinergic receptor activated by elevated levels of extracellular ATP, which typically occurs during inflammatory conditions. Activation of P2RX7 by αSyn is implicated in neuronal degeneration, potentially causing pore dilation and increased inflammation. By integrating the data curation, molecular docking, and molecular dynamics (MD) simulations, along with structural analyses, we attempted to elucidate the molecular mechanisms and binding sites for P2RX7-αSyn interaction. We elucidated interactions between P2RX7 and the N-terminal domain (NTD) of αSyn. Utilizing cryo-EM structures of P2RX7 in ATP-bound and unbound states, we assessed αSyn's effect on P2RX7 structural and functional dynamics. Initially, the analyses revealed that αSyn interactomes are mainly involved in mitochondrial functions, while P2RX7 interactors are linked to receptor internalization and calcium transport. Molecular docking with six tools identified that αSyn-NTD fragments preferentially bind to the proximal region of P2RX7's transmembrane domain. Microsecond all atom MD simulations in a POPS lipid bilayer showed significant atomic fluctuations, particularly in the head region, lower body, and large loop of P2RX7's cytoplasmic domain. Secondary structure analysis indicated unfolding in regions related to pore dilation and receptor desensitization. Further by contact-based and solvent accessibility analyses, along with protein structure network (PSN) studies, we identified crucial residues involved in αSyn-P2RX7 interactions. This understanding enhances the knowledge of how αSyn and P2RX7 interactions take place, potentially contributing to neurodegenerative diseases, and could be instrumental in developing future preventive and therapeutic approaches.

Microglia-driven inflammation induces progressive tauopathies and synucleinopathies

Alzheimer's disease and Parkinson's disease are characterized by distinct types of abnormal protein aggregates within neurons. These aggregates are known as neurofibrillary tangles and Lewy bodies, which consist of tau and α-synuclein, respectively. As the diseases progress, these aggregates spread from one cell to another, causing protein pathology to affect broader regions of the brain. Another notable characteristic of these diseases is neuroinflammation, which occurs when microglia become activated. Recent studies have suggested that inflammation may contribute to the formation and propagation of protein aggregates. However, it remains unclear whether microglia-driven inflammation can initiate and propagate different proteinopathies and associated neuropathology in neurodegenerative diseases. Here, using single-cell RNA sequencing, we observed that microglia exposed to α-synuclein or tau underwent changes in their characteristics and displayed distinct types of inflammatory response. The naive mice that received these microglial cell transplants developed both tauopathy and synucleinopathy, along with gliosis and inflammation. Importantly, these pathological features were not limited to the injection sites but also spread to other regions of the brain, including the opposite hemisphere. In conjunction with these pathological changes, the mice experienced progressive motor and cognitive deficits. These findings conclusively demonstrate that microglia-driven inflammation alone can trigger the full range of pathological features observed in neurodegenerative diseases, and that inflammation-induced local neuropathology can spread to larger brain regions. Consequently, these results suggest that microglia-driven inflammation plays an early and pivotal role in the development of neurodegenerative diseases. The transplantation of microglia activated by αSyn or tau proteins into the brains of naive mice resulted in the formation of synucleinopathy, tauopathy, gliosis, neuroinflammation and behavioral abnormalities. Activated microglia displayed alterations in subclusters as well as the corresponding feature genes.

Redefining Non-Motor Symptoms in Parkinson's Disease

Parkinson's disease involves widespread neurodegeneration that extends far beyond the basal ganglia, giving rise to a diverse range of non-motor symptoms that frequently emerge before motor onset. These include autonomic dysfunction, cognitive decline, neuropsychiatric disturbances, sleep-related disorders, and sensory deficits. Here, we synthesize current evidence on the anatomical, neurochemical, and network-level mechanisms that drive these symptoms, and we examine how they shape disease progression and clinical heterogeneity. We highlight the limitations of dopamine-centric models and advocate for a framework that treats non-motor symptoms as the disorder's primary, mechanistically distinct features. We also discuss how emerging technologies-such as multi-omic profiling, artificial intelligence, and network neuroscience-enable earlier identification, stratification of non-motor phenotypes, and the development of precision-based therapeutic strategies. Recognizing non-motor symptoms as central to Parkinson's disease redefines how the disorder should be diagnosed, studied, and treated.

Effects of herbaceous bioflavonoid herbacetin on oxidative stress, and alpha-synuclein regulation, programmed cell death in a Parkinson illness

BACKGROUND

Herbacetin, a flavonoid present in many types of herbs, which include linaceae, ephedraceae, and crassulaceae, exhibits a range of medicinal properties. 1-methyl-4-phenylpyridinium (MPP+) is one of the neurotoxins used in cell-based Parkinson's disease (PI) models. Whereas the precise chemical mechanism of iron association with free radical cell damage and apoptosis is yet unknown, intracellular irons are a key factor for MPP+-derived apoptosis.

METHODS

We examine whether the antiapoptotic properties of flaxseed bioflavonoid herbacetin (HB) are associated with the stimulation of the intrinsic caspase-dependent pathway and exposing of MPP+ caused neuronal death in the human dopaminergic neuroblastoma cells. Four groups were created out of the cells. Groups I, II, III, and IV are the control, HB+MPP+, MPP+, and HB, respectively. Following a 24-hour incubation period, the cells were subjected to several parameters.

RESULTS

We discovered in neuroblastoma cells that HB dramatically reduced the cell death induced by MPP+. Additionally, HB significantly reduced the formation of ROS and counteracted the reduction in MMP resulting from MPP+ treatment. HB reduces the stimulation of the intrinsic caspase-dependent apoptotic mechanism and suppresses the MPP+-mediated apoptotic signalling pathway. Furthermore, HB predicted a better binding interaction with alpha-synuclein and drastically decreased alpha-synuclein expression and accumulation in neuroblastoma cells.

CONCLUSION

Consequently, our findings imply that HB shields neurons by reducing oxidative stress, alpha-synuclein misfolding in neuroblastoma, and apoptosis prompts the death of neuroblastoma cells.

Differential neuronal vulnerability to C9orf72 repeat expansion driven by Xbp1-induced endoplasmic reticulum-associated degradation

Neurodegenerative diseases are characterized by the localized loss of neurons. Why cell death is triggered only in specific neuronal populations and whether it is the response to toxic insults or the initial cellular state that determines their vulnerability is unknown. To understand individual cell responses to disease, we profiled their transcriptional signatures throughout disease development in a Drosophila model of C9orf72 (G4C2) repeat expansion (C9), the most common genetic cause of frontotemporal dementia and amyotrophic lateral sclerosis. We identified neuronal populations specifically vulnerable or resistant to C9 expression and found an upregulation of protein homeostasis pathways in resistant neurons at baseline. Overexpression of Xbp1s, a key regulator of the unfolded protein response and a central node in the resistance network, rescues C9 toxicity. This study shows that neuronal vulnerability depends on the intrinsic transcriptional state of neurons and that leveraging resistant neurons' properties can boost resistance in vulnerable neurons.

Strategies for Acid and Amine Cross-linking and Labeling for Protein Structural Characterization Using Mass Spectrometry

Cross-linking and covalent labeling are common tools for protein structural elucidation by mass spectrometry. However, despite the importance of electrostatic interactions in proteins, there are not many tools for probing both acids and amines. Therefore, we introduce novel solution-phase amine-to-acid cross-linkers and single reagent amine and acid covalent labels utilizing carbodiimide chemistry. Cross-linking and labeling sites were determined using top-down and enzymatic digestion approaches. Ubiquitin was chosen as a model protein for isotopically labeled 13C-15N-glycine cross-linking/covalent labeling and glycyl-l-proline cross-linking/covalent labeling with top-down mass spectrometry as a proof of concept. Alpha synuclein, an intrinsically disordered protein that plays a role in multiple neurological disorders, was also cross-linked/covalent labeled with these methods/reagents. We expect that these structural characterization techniques will play a role in gaining insight into functionally and pathologically important structural tendencies of disordered proteins.

Malondialdehyde Mediated Alpha-Synuclein Aggregation: A Plausible Etiology of Parkinson's Disease in Oxidative Stress

Malondialdehyde (MDA), a major reactive byproduct of lipid peroxidation, has been implicated in numerous pathological conditions as a result of altering the structure and function of crucial proteins. One such protein is α-synuclein (α-Syn), which plays a vital role in the pathogenesis of Parkinson's disease (PD). This study investigates the hypothesis that MDA causes structural alterations in α-Syn, promoting its aggregation and exacerbating its toxicological effects. In vivo experiments were conducted where MDA and MDA-modified α-Syn were injected to the brain of mice. Behavioral assessments were performed to evaluate motor function changes, while immunohistochemistry was employed to examine the extent of α-Syn aggregation in brain tissues. An extraction protocol was also developed exquisitely, enabling quantification of modified α-Syn from brain tissue. Moreover, 15Nitrogen-labeled α-Syn was employed to establish an absolute quantification method on nLC-HRMS/MS. Our findings demonstrate that MDA-induced modifications in α-Syn alter its structural properties and also significantly enhance its aggregation propensity, potentially contributing to the neurodegenerative processes observed in PD. The developed model displayed a nonreversible decline in motor function, neurodegeneration, and aggregation of proteins in the brain mimicking the PD conditions. This research provides valuable insights into the molecular mechanisms of PD, emphasizing the role of MDA-modified proteins in the etiology of PD.

Caffeine and Nicotine with N-Substituted Diazirine Photoaffinity Labels Form Adducts at Tyrosine-39 of α-Synuclein

Aggregates of the protein α-synuclein are found in Lewy bodies in the brains of Parkinson's disease (PD) patients. Small molecules that can attenuate or halt α-synuclein aggregation have been studied as potential therapeutics for PD. However, we have a limited understanding of how these molecules bind to α-synuclein. We previously identified that caffeine, nicotine, and 1-aminoindan all bind to both the N- and C-terminus of α-synuclein, although the binding location remains unknown. In an effort to identify these binding regions on α-synuclein, we synthesized diazirine photoaffinity probes attached to caffeine (C-Dz), nicotine (N-Dz), and 1-aminoindan (I-Dz) and allowed each to react with α-synuclein in vitro. We then treated the incubation mixture with trypsin and employed time-of-flight mass spectrometry to analyze the resulting peptides. Our findings reveal a distinctive binding pattern among the probes: C-Dz forms covalent bonds with Tyr-39 and Glu-20, while N-Dz selectively forms a covalent bond with Tyr-39. Intriguingly, we could not detect the labeling of I-Dz to any specific amino acids. All of the diazirine-bound peptides were found near the N-terminus. Our results suggest that the N-terminal region near Tyr-39 bears further study to elucidate the binding interactions of small molecules with α-synuclein and may be a target for anti-PD agents.

Unravelling the Proteinopathic Engagement of α-Synuclein, Tau, and Amyloid Beta in Parkinson's Disease: Mitochondrial Collapse as a Pivotal Driver of Neurodegeneration

Parkinson's disease is a complex neurological ailment manifested by dopaminergic neurodegeneration in the substantia nigra of the brain. This study investigates the molecular tripartite interaction between Lewy bodies, amyloid beta, and tau protein in the pathogenesis of Parkinson's disease. Lewy bodies which have been found as the important pathological hallmark in the degenerative neurons of Parkinson's patients, are mainly composed of α-synuclein. The accumulation of α-synuclein has been directly and indirectly linked to the severity and degree of progression of the disease. In addition, approximately 50% of Parkinson's disease cases are also described by hyperphosphorylation of tau protein indicating its significant involvement in the disease. The study further explains how α-synuclein, tau and amyloid beta can spread via cross-seeding mechanisms and accelerate each other's aggregation leading to neuronal death. Both GSK-3β and CDK5 are involved in phosphorylation which among other effects contributes to the misfolding of both α-synuclein and tau proteins that lead to neurodegeneration in Alzheimer's disease. Several mediators, that contribute to mitochondrial damage through elevated oxidative stress pathology are clearly described. Because of the increase in the incidence of Parkinson's disease, as predicted to be 17 million when the study was being conducted, studying these pathological mechanisms is very important in trying to establish treatments. This work contributes a path to finding a multi-target treatment regimen to alleviate the burden of this devastating disease.

Repurposing major metabolites of lamiaceae family as potential inhibitors of α-synuclein aggregation to alleviate neurodegenerative diseases: an in silico approach

Neurodegenerative disorders (NDs) are typically characterized by progressive loss of neuronal function and the deposition of misfolded proteins in the brain and peripheral organs. They are molecularly classified based on the specific proteins involved, underscoring the critical role of protein-processing systems in their pathogenesis. Alpha-synuclein (α-syn) is a neural protein that is crucial in initiating and progressing various NDs by directly or indirectly regulating other ND-associated proteins. Therefore, reducing the α-syn aggregation can be an excellent option for combating ND initiation and progression. This study presents an in silico phytochemical-based approach for discovering novel neuroprotective agents from bioactive compounds of the Lamiaceae family, highlighting the potential of computational methods such as functional networking, pathway enrichment analysis, molecular docking, and simulation in therapeutic discovery. Functional network and enrichment pathway analysis established the direct or indirect involvement of α-syn in various NDs. Furthermore, molecular docking interaction and simulation studies were conducted to screen 85 major bioactive compounds of the Lamiaceae family against the α-syn aggregation. The results showed that five compounds (α-copaene, γ-eudesmol, carnosol, cedryl acetate, and spathulenol) had a high binding affinity towards α-syn with potential inhibitory activity towards its aggregation. MD simulations validated the stability of the molecular interactions determined by molecular docking. In addition, in silico pharmacokinetic analysis underscores their potential as promising drug candidates, demonstrating excellent blood-brain barrier (BBB) permeability, bioactivity, and reduced toxicity. In summary, this study identifies the most suitable compounds for targeting the α-syn aggregation and recommends these compounds as potential therapeutic agents against various NDs, pending further in vitro and in vivo validation.

Potential therapeutic effects of curcumin, with or without L-DOPA, on motor and cognitive functions and hippocampal changes in rotenone-treated rats

The neurodegenerative condition known as Parkinson's disease (PD) is a long-term condition that causes both motor and non-motor symptoms. It is known that curcumin has a strong neuroprotective potential. This experimental study was designed to examine the anti-inflammatory, anti-apoptotic and neuroprotective effects of curcumin administered alone and in combination with L-DOPA in the hippocampus as well as behavioral symptoms in rotenone-induced PD model. Forty-two 4-month-old adult male Wistar rats were randomly divided into six groups as follows: Control, Curcumin, Rotenone, Rotenone plus curcumin, Rotenone plus L-DOPA and Rotenone plus curcumin plus L-DOPA. Control group received vehicles, curcumin group received curcumin (200 mg kg-1, daily for 35 days), rotenone group received rotenone (2 mg kg-1, daily for 35 days), and test groups received curcumin or L-DOPA (10 mg kg-1, daily for the last 15 days) or their combination in addition the rotenone. Pole, sucrose preference, open field, elevated plus maze, and Morris water maze tests were performed after treatment. Molecular and biochemical analyses were performed in the hippocampus tissue and serum samples. Rotenone injection caused impairments in motor activity, depressive-like behavior, and learning and memory functions. Rotenone also increased the expressions of α-synuclein, caspase 3, NF-κB, and decreased the expressions of parkin and BDNF in the hippocampus. However, especially curcumin and L-DOPA combined treatment normalized all these impaired molecular and behavioral variables. In conclusion, curcumin may exert beneficial effects in treatment strategies for PD-related hippocampal effects, especially when added to L-DOPA therapy.

The pharmacodynamics-based prophylactic benefits of GLP-1 receptor agonists and SGLT2 inhibitors on neurodegenerative diseases: evidence from a network meta-analysis

BACKGROUND

Glucagon-like peptide-1 (GLP-1) receptor agonists and sodium-glucose cotransporter 2 (SGLT2) inhibitors represent a new generation of antihyperglycemic agents that operate through mechanisms distinct from conventional diabetes treatments. Beyond their metabolic effects, these medications have demonstrated neuroprotective properties in preclinical studies. While clinical trials have explored their therapeutic potential in established neurodegenerative conditions, their role in disease prevention remains unclear. We conducted a network meta-analysis (NMA) to comprehensively evaluate the prophylactic benefits of these agents across multiple neurodegenerative diseases and identify the most promising preventive strategies.

METHODS

We systematically searched PubMed, Embase, ClinicalKey, Cochrane CENTRAL, ProQuest, ScienceDirect, Web of Science, and ClinicalTrials.gov through October 24th, 2024, for randomized controlled trials (RCTs) of GLP-1 receptor agonists or SGLT2 inhibitors. Our primary outcome was the incidence of seven major neurodegenerative diseases: Parkinson's disease, Alzheimer's disease, Lewy body dementia, multiple sclerosis, amyotrophic lateral sclerosis, frontotemporal dementia, and Huntington's disease. Secondary outcomes included safety profiles assessed through dropout rates. We performed a frequentist-based NMA and evaluated risk of bias with Risk of Bias tool. The main result of the primary outcome in the current study would be re-affirmed via sensitivity test with Bayesian-based NMA.

RESULTS

Our analysis encompassed 22 RCTs involving 138,282 participants (mean age 64.8 years, 36.4% female). Among all investigated medications, only dapagliflozin demonstrated significant prophylactic benefits, specifically in preventing Parkinson's disease (odds ratio = 0.28, 95% confidence intervals = 0.09 to 0.93) compared to controls. Neither GLP-1 receptor agonists nor other SGLT2 inhibitors showed significant preventive effects for any of the investigated neurodegenerative conditions. Drop-out rates were comparable across all treatments.

CONCLUSIONS

This comprehensive NMA reveals a novel and specific prophylactic effect of dapagliflozin against Parkinson's disease, representing a potential breakthrough in preventive neurology. The specificity of dapagliflozin's protective effect to Parkinson's disease might rely on its highly selective inhibition to SGLT2. These findings provide important direction for future research and could inform preventive strategies for populations at risk of Parkinson's disease.

TRIAL REGISTRATION

PROSPERO CRD42021252381.

Nanopore sensing of protein and peptide conformation for point-of-care applications

The global population's aging and growth will likely result in an increase in chronic aging-related diseases. Early diagnosis could improve the medical care and quality of life. Many diseases are linked to misfolding or conformational changes in biomarker peptides and proteins, which affect their function and binding properties. Current clinical methods struggle to detect and quantify these changes. Therefore, there is a need for sensitive conformational sensors that can detect low-concentration analytes in biofluids. Nanopore electrical detection has shown potential in sensing subtle protein and peptide conformation changes. This technique can detect single molecules label-free while distinguishing shape or physicochemical property changes. Its proven sensitivity makes nanopore sensing technology promising for ultra-sensitive, personalized point-of-care devices. We focus on the capability of nanopore sensing for detecting and quantifying conformational modifications and enantiomers in biomarker proteins and peptides and discuss this technology as a solution to future societal health challenges.

Meta-analysis of the make-up and properties of in vitro models of the healthy and diseased blood-brain barrier

In vitro models of the human blood-brain barrier (BBB) are increasingly used to develop therapeutics that can cross the BBB for treating diseases of the central nervous system. Here we report a meta-analysis of the make-up and properties of transwell and microfluidic models of the healthy BBB and of BBBs in glioblastoma, Alzheimer's disease, Parkinson's disease and inflammatory diseases. We found that the type of model, the culture method (static or dynamic), the cell types and cell ratios, and the biomaterials employed as extracellular matrix are all crucial to recapitulate the low permeability and high expression of tight-junction proteins of the BBB, and to obtain high trans-endothelial electrical resistance. Specifically, for models of the healthy BBB, the inclusion of endothelial cells and pericytes as well as physiological shear stresses (~10-20 dyne cm-2) are necessary, and when astrocytes are added, astrocytes or pericytes should outnumber endothelial cells. We expect this meta-analysis to facilitate the design of increasingly physiological models of the BBB.

PET tracer development for imaging α-synucleinopathies

Abnormal α-synuclein aggregation is a key neuropathological hallmark of α-synucleinopathies, such as Parkinson's disease (PD), multiple system atrophy (MSA), and several other neurological disorders, and closely contributes to pathogenesis. The primary characteristics of α-synucleinopathies are selective targeted neurodegeneration and the accumulation of Lewy pathologies. Specifically, α-synuclein positron emission tomography (PET) radiotracers target the fibrillar forms of the protein, thus enhancing early diagnosis and the evaluation of treatment effectiveness for various α-synucleinopathies. Therefore, in vivo detection of α-synuclein aggregates using targeted radiolabeled probes would aid in drug development, early diagnosis, and ongoing disease monitoring. As such, no promising α-synuclein biomarkers suitable for clinical applications have been reported. PET is a valuable non-invasive technique for imaging drug distribution in tissues and receptor occupancy at target sites in living animals and humans. Advances in PET biomarkers have significantly enhanced our understanding of the mechanisms underlying PD. This review summarizes recent ongoing efforts in the development of selective PET tracers for α-synuclein and discusses future perspectives.

Parkinson's Disease Modeling Using Directly Converted 3D Induced Dopaminergic Neuron Organoids and Assembloids

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons and the accumulation of α-synuclein aggregates, yet current models inadequately mimic the complex human brain environment. Recent advances in brain organoid models offer a more physiologically relevant platform for studying PD, however, iPSC-derived brain organoids require long maturation times and may not accurately represent the aged brain's epigenetics and cellular contexts, limiting their applicability for modeling late-onset diseases like PD. In this study, a novel approach for generating 3D-induced dopaminergic (iDA) neuron organoids directly from human fibroblasts is presented. It is confirmed that these 3D iDA organoids more closely resemble the aged human brain and accurately replicate PD pathologies. Furthermore, this model is extended by incorporating astrocytes to create 3D iDA neuron-astrocyte assembloids, recognizing the critical role of glial cells in neurodegenerative processes. It is identified that PD assembloids incorporating control astrocytes with A53T mutant iDAs demonstrated the neuroprotective effects of healthy astrocytes. In contrast, A53T mutant astrocytes progressively contributed to neuronal degeneration and synucleinopathy in 3D-iDA assembloids. These findings suggest that directly converted 3D-iDA organoids and assembloids provide a robust and physiologically relevant model for studying PD pathogenesis and evaluating therapeutic interventions.

Criterion for Assessing Accumulated Neurotoxicity of Alpha-Synuclein Oligomers in Parkinson's Disease

The paper introduces a parameter called "accumulated neurotoxicity" of α-syn oligomers, which measures the cumulative damage these toxic species inflict on neurons over time, given the years it typically takes for such damage to manifest. A threshold value for accumulated neurotoxicity is estimated, beyond which neuron death is likely. Numerical results suggest that rapid deposition of α-syn oligomers into fibrils minimizes neurotoxicity, indicating that the formation of Lewy bodies might play a neuroprotective role. Strategies such as reducing α-syn monomer production or enhancing degradation can decrease accumulated neurotoxicity. In contrast, slower degradation (reflected by longer half-lives of monomers and free aggregates) increases neurotoxicity, supporting the idea that impaired protein degradation may contribute to Parkinson's disease progression. Accumulated neurotoxicity is highly sensitive to the half-deposition time of free α-syn aggregates into fibrils, exhibiting a sharp increase as it transitions from negligible to elevated levels, indicative of neural damage.

Early Alterations in De Novo Parkinson's Disease Revealed by Diffusion Tensor Imaging: Preliminary Study

Background/Objectives: Parkinson's disease (PD) is characterized by progressive neurodegeneration affecting both motor and non-motor functions. Identifying early alterations in PD patients before the onset of dopaminergic therapy is crucial for understanding disease progression and developing targeted interventions. This study aimed to investigate early changes in the putamen and thalamus in de novo PD patients using diffusion tensor imaging (DTI) compared to healthy controls. Methods: Thirty-one de novo PD patients and thirty-three healthy controls underwent DTI scanning. Tract-based spatial statistics were used to compare fractional anisotropy (FA) values between groups. Results: De novo PD patients exhibited significantly lower FA values in the right thalamus compared to controls, suggesting alterations in neuronal integrity or fiber degeneration in the early stages of the disease. However, no significant differences were demonstrated for FA values in the putamen between groups. Conclusions: We demonstrated that the FA value in the right thalamus was lower in PD compared with healthy controls. These findings highlight the potential of DTI as a non-invasive tool for detecting early neural changes in PD patients. Further studies would be helpful to assess the clinical utility of serial FA measurements of the subcortical gray matter in objective quantification of disease progression and monitoring of the therapeutic response.

Harnessing the Potential of Walnut Leaves from Nerpio: Unveiling Extraction Techniques and Bioactivity Through Caenorhabditis elegans Studies

This study used Juglans regia leaves from the Gran Jefe variety; this indigenous cultivar from Nerpio is highly valued for its quality and distinct characteristics. This type of walnut is traditionally cultivated in the region and is noted for its organoleptic properties and adaptation to local climatic conditions. Two solvents were tested to determine the optimal extraction conditions for phenolic compounds: 80% ethanol and water. Direct homogenization with an Ultra-Turrax, direct ultrasound, and indirect ultrasound treatments were compared for ethanol extraction. Water extractions were conducted using direct and indirect ultrasound, infusion, and decoction. Compared to water extraction, 80% ethanol proved to be more efficient. Extracting phenolic compounds from 'Gran Jefe' walnut leaves was most effective when using direct extraction methods without either ultrasound assistance or indirect ultrasound treatment. The main compounds identified were trans-3-caffeoylquinic acid and quercetin-3-hexoside isomer 1. The ethanolic extract obtained through direct extraction was selected to study further the bioactivities of 'Gran Jefe' walnut leaves using C. elegans as an in vivo model. Results indicated that the leaf extract enhanced thermal and oxidative stress resistance, promoted fertility, and exhibited neuroprotective effects in models of Alzheimer's and Parkinson's diseases. The observed bioactivities were attributed to the free phenolics present in the ethanolic extract.

New Insights on the Potential Role of Pyroptosis in Parkinson's Neuropathology and Therapeutic Targeting of NLRP3 Inflammasome with Recent Advances in Nanoparticle-Based miRNA Therapeutics

Parkinson's disease (PD) is a widespread neurodegenerative disorder characterized by the gradual degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNc). This review aims to summarize the recent advancements in the pathophysiological mechanisms of pyroptosis, mediated by NLRP3 inflammasome, in advancing PD and the anti-pyroptotic agents that target NLRP3 inflammatory pathways and miRNA. PD pathophysiology is primarily linked to the aggregation of α-synuclein, the overproduction of reactive oxygen species (ROS), and the development of neuroinflammation due to microglial activation. Prior research indicated that a significant quantity of microglia is activated in both PD patients and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse models, triggering neuroinflammation and resulting in a cascade of cellular death. Microglia possess an inflammatory complex pathway termed the nucleotide-binding oligomerization domain-, leucine-rich repeat, and pyrin domain-containing 3 (NLRP3) inflammasome. Activation of the NLRP-3 inflammasome results in innate cytokines maturation, including IL-18 and IL-1β, which initiates the neuroinflammatory signal and induces a type of inflammatory cell death known as pyroptosis. Upon neuronal damage, intracellular levels of damage-associated molecular patterns (DAMPs), including reactive oxygen species (ROS), would build. DAMPs induce unregulated cell death and subsequent release of oxidative intermediates and pro-inflammatory cytokines, leading to the progression of PD. Thus, targeting of neuroinflammation using antipyroptotic medications can be efficiently achieved by blocking NLRP3 and obstructing IL-1β signaling and release. Furthermore, many research studies showed that miRNAs have been identified as regulators of the NLRP3 inflammasome and Nrf2 signal, which subsequently modulate the NLRP3-Nrf2 axis in PD. Nanotechnology promises potential for the advancement of miRNA-based therapies. Nanoparticles that ensure miRNA stability, traverse the blood-brain barrier (BBB) and distribute miRNA targeting regions needed to be created. In conclusion, targeting the pyroptosis pathway via NLRP3 or miRNA may serve as a prospective therapeutic strategy for PD in the future.

Alpha synuclein co-pathology is associated with accelerated amyloid-driven tau accumulation in Alzheimer's disease

BACKGROUND

Aggregated alpha-Synuclein (αSyn) is a hallmark pathology in Parkinson's disease but also one of the most common co-pathologies in Alzheimer's disease (AD). Preclinical studies suggest that αSyn can exacerbate tau aggregation, implying that αSyn co-pathology may specifically contribute to the Aβ-induced aggregation of tau that drives neurodegeneration and cognitive decline in AD. To investigate this, we combined a novel CSF-based seed-amplification assay (SAA) to determine αSyn positivity with amyloid- and tau-PET neuroimaging in a large cohort ranging from cognitively normal individuals to those with dementia, examining whether αSyn co-pathology accelerates Aβ-driven tau accumulation and cognitive decline.

METHODS

In 284 Aβ-positive and 308 Aβ-negative subjects, we employed amyloid-PET, Flortaucipir tau-PET, and a CSF-based αSyn seed-amplification assay (SAA) to detect in vivo αSyn aggregation. CSF p-tau181 measures were available for 384 subjects to assess earliest tau abnormalities. A subset of 155 Aβ-positive and 135 Aβ-negative subjects underwent longitudinal tau-PET over approximately 2.5 years. Using linear regression models, we analyzed whether αSyn SAA positivity was linked to stronger Aβ-related increases in baseline fluid and PET tau biomarkers, faster Aβ-driven tau-PET increase, and more rapid cognitive decline.

RESULTS

αSyn SAA positivity was more common in Aβ + vs. Aβ- subjects and increased with clinical severity (p < 0.001). Most importantly, αSyn positivity was also associated with greater amyloid-associated CSF p-tau181 increases (p = 0.005) and higher tau-PET levels in AD-typical brain regions (p = 0.006). Longitudinal analyses confirmed further that αSyn positivity was associated with faster amyloid-related tau accumulation (p = 0.029) and accelerated amyloid-related cognitive decline, potentially driven driven by stronger tau pathology.

CONCLUSIONS

Our findings suggest that αSyn co-pathology, detectable via CSF-based SAAs, is more prevalent in advanced AD and contributes to the development of aggregated tau pathology thereby driving faster cognitive decline. This highlights that a-Syn co-pathology may specifically accelerate amyloid-driven tau pathophysiology in AD, underscoring the need to consider αSyn in AD research and treatment strategies.

A Focus on the Link Between Metal Dyshomeostasis, Norepinephrine, and Protein Aggregation

Neurodegenerative disorders are one of the main public health problems worldwide and, for this reason, they have attracted the attention of several researchers who aim to better understand the molecular processes linked to the etiology of these disorders, including Alzheimer's and Parkinson's diseases. In this review, we describe both the beneficial and toxic effect of norepinephrine (NE) and its connected ROS/metal-mediated pathways, which end in neuromelanin (NM) formation and protein aggregation. In particular, we emphasize the importance of stabilizing the delicate homeostatic balance that regulates (i) the metal/ROS-promoted oxidation of catecholamines, as NE, and (ii) the generation of oxidative by-products capable of covalently and non-covalently modifying neuroproteins, thus altering their stability and their oligomerization; these processes may end in (iii) the incorporation of protein conjugates into vesicles, which then evolve into neuromelanin (NM) organelles. In general, we aim to provide an up-to-date overview of the challenges and controversies emerging from the current literature to delineate a direction for future research.

The Effects of Air Pollution on Neurological Diseases: A Narrative Review on Causes and Mechanisms

Air pollution has well-documented adverse effects on human health; however, its impact on neurological diseases remains underrecognized. The mechanisms by which various components of air pollutants contribute to neurological disorders are not yet fully understood. This review focuses on key air pollutants, including particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and diesel exhaust particles (DEPs). This paper summarizes key findings on the effects of air pollution on neurological disorders, including autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), Alzheimer's disease (AD), and Parkinson's disease (PD). Although the precise biological mechanisms remain to be fully elucidated, evidence suggests that multiple pathways are involved, including blood-brain barrier disruption, oxidative stress, inflammation, and the activation of microglia and astrocytes. This review underscores the role of environmental pollutants as significant risk factors for various neurological diseases and explores their mechanisms of action. By advancing our understanding of these interactions, this work aims to inform new insights for mitigating the adverse effects of air pollution on neurological diseases, ultimately contributing to the establishment of a cleaner and healthier environment for future generations.

Parkinson's disease and metabolic disorders, understanding their shared co-morbidity through the autonomic nervous system

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor and nonmotor dysfunctions. Its pathological hallmark is the aggregation of ɑ-synuclein in the central nervous system (CNS), leading to widespread loss of dopaminergic neurons in the substantia nigra (SN). Interestingly, metabolic disorders localized in the periphery, such as diabetes mellitus, frequently co-occur with PD. Emerging evidence highlights a bidirectional relationship: metabolic diseases may accelerate PD progression, while PD can exacerbate metabolic dysfunction. Beyond these associations, a growing body of research suggests that dysfunction in the peripheral nervous system, the primary communication bridge between the brain and peripheral organs, plays a critical role in these comorbidities. Autonomic nerve perturbation may accelerate dopaminergic neuronal loss in the SN and exacerbate metabolic dysregulation. This chapter synthesizes current evidence linking autonomic dysfunction with the progression of PD and related metabolic disorders, and it explores innovative therapeutic strategies leveraging this bidirectional relationship to address PD progression.

Alterations in non-REM sleep and EEG spectra precede REM-sleep deficits in a model of synucleinopathy

BackgroundSleep disturbances often precede motor symptoms in neurodegenerative diseases like Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Neuroinflammation is implicated in PD pathophysiology and may contribute to non-motor symptoms such as sleep disturbances. The Thy1-αSyn mouse model, overexpressing human alpha-synuclein (αSyn), mimics key aspects of PD and DLB, making it valuable for studying related sleep disturbances and neuroinflammatory changes.ObjectiveTo investigate early-stage alterations in sleep architecture, electroencephalographic (EEG) patterns, and neuroinflammation in Thy1-αSyn mice.MethodsWe used telemetric EEG/electromyography (EMG) with video surveillance to compare sleep patterns and EEG spectral power between 2.5- and 4.5-month-old male Thy1-αSyn transgenic mice and wild-type littermates. Neuroinflammation was assessed by examining microglial (Iba1) and astrocytic (GFAP) activation in key sleep-regulating brain regions.ResultsThy1-αSyn mice showed decreased resting wake time and increased non-REM sleep, with altered sleep bout frequency and length, indicating significant sleep architecture changes. Spectral analysis revealed a shift from higher to lower frequency bands, suggesting early neural circuitry disruptions due to αSyn overexpression. Significant microglial activation was observed at 3 months, with astrogliosis progressing by 5 months in key sleep-regulating regions, indicating that neuroinflammation may contribute to the observed sleep disturbances.ConclusionsEarly-stage Thy1-αSyn mice exhibit significant sleep architecture changes, EEG spectral shifts, and neuroinflammatory alterations. These findings suggest that neuroinflammation may play a role in the initial pathophysiological changes in PD and related synucleinopathies. Sleep, EEG, and neuroinflammatory changes could serve as early biomarkers for these diseases.

Does drug repurposing bridge the gaps in management of Parkinson's disease? Unravelling the facts and fallacies

Repurposing the existing drugs for the management of both common and rare diseases is increasingly appealing due to challenges such as high attrition rates, the economy, and the slow pace of discovering new drugs. Drug repurposing involves the utilization of existing medications to treat diseases for which they were not originally intended. Despite encountering scientific and economic challenges, the pharmaceutical industry is intrigued by the potential to uncover new indications for medications. Medication repurposing is applicable across different stages of drug development, with the greatest potential observed when the drug has undergone prior safety testing. In this review, strategies for repurposing drugs for Parkinson's disease (PD) are outlined, a neurodegenerative disorder predominantly impacting dopaminergic neurons in the substantia nigra pars compacta region. PD is a debilitating neurodegenerative condition marked by an amalgam of motor and non-motor symptoms. Despite the availability of certain symptomatic treatments, particularly targeting motor symptoms, there remains a lack of established drugs capable of modifying the clinical course of PD, leading to its unchecked progression. Although standard drug discovery initiatives focusing on treatments that relieve diseases have yielded valuable understanding into the underlying mechanisms of PD, none of the numerous promising candidates identified in preclinical studies have successfully transitioned into clinically effective medications. Due to the substantial expenses associated with drug discovery endeavors, it is understandable that there has been a notable shift towards drug reprofiling strategies. Assessing the efficacy of an existing medication offers the additional advantage of circumventing the requirement for preclinical safety assessments and formulation enhancements, consequently streamlining the process and reducing both the duration of time and financial investments involved in bringing a treatment to clinical fruition. Furthermore, repurposed drugs may benefit from lower rates of failure, presenting an additional potential advantage. Various strategies for repurposing drugs are available to researchers in the field of PD. Some of these strategies have demonstrated effectiveness in identifying appropriate drugs for clinical trials, thereby providing validation for such strategies. This review provides an overview of the diverse strategies employed for drug reprofiling from approaches that place emphasis on single-gene transcriptional investigations to comprehensive epidemiological correlation analysis. Additionally, instances of previous or current research endeavors employing each strategy have been discussed. For the strategies that have not been yet implemented in PD research, their strategic efficacy is demonstrated using examples involving other disorders. In this review, we assess the safety and efficacy potential of prominent candidates repurposed as potential treatments for modifying the course of PD undergoing advanced clinical trials.

Presynaptic terminal integrity is associated with glucose metabolism in Parkinson's disease

OBJECTIVE

To investigate the relationship of synaptic loss with glucose metabolism and dopaminergic transporters in Parkinson's disease (PD) patients.

METHODS

A total of 16 patients with PD and 11 age-matched healthy controls underwent positron emission tomography (PET) with the tracers [18F]SynVesT-1, a ligand for the presynaptic terminal marker synaptic vesicle protein 2 A (SV2A), and FDG. PD patients also underwent PET with the dopamine transporter (DAT) ligand [18F]FP-CIT. The difference in synaptic density between PD patients and age-matched normal controls(NCs) was determined in the selected regions of interest, and the correlations of the [18F]SynVesT-1 PET SUVRs with [18F]FP-CIT PET SUVRs and [18F]FDG PET SUVRs were evaluated.

RESULTS

Compared with that in the NC group, the synaptic density in the caudate region was significantly lower in the PD group (SUVR: 2.51 ± 0.36 vs. 3.18 ± 0.32, p < 0.001), especially in the pre-commissural caudate and post-commissural caudate (SUVR: 2.42 ± 0.29 vs. 2.63 ± 0.32, p < 0.01; 0.76 ± 0.31 vs. 0.97 ± 0.33, p < 0.001). A reduced synaptic density was significantly correlated with DAT (r = 0.61, p < 0.001) and glucose metabolism (r = 0.73, p < 0.001) in the post-commissural caudate. In the post-commissural regions of the caudate, there was a partial mediating effect of synaptic density on the relationship between glucose metabolism and DAT availability (indirect effect: β4 = 0.039, p = 0.024).

CONCLUSION

[18F]SynVesT-1 binds specifically to SV2A, reflecting synaptic density, and there is a positive correlation metabolic pattern related to the changes reflected by [18F]SynVesT-1 and [18F]FDG.

Comprehensive mapping of mutations in TDP-43 and α-Synuclein that affect stability and binding

Abnormal aggregation and amyloid inclusions of TAR DNA-binding protein 43 (TDP-43) and α-Synuclein (α-Syn) are frequently co-observed in amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease. Several reports showed TDP-43 C-terminal domain (CTD) and α-Syn interact with each other and the aggregates of these two proteins colocalized together in different cellular and animal models. Molecular dynamics simulation was conducted to elucidate the stability of the TDP-43 and Syn complex structure. The interfacial mutations in protein complexes changes the stability and binding affinity of the protein that may cause diseases. Here, we have utilized the computational saturation mutagenesis approach including structure-based stability and binding energy calculations to compute the systemic effects of missense mutations of TDP-43 CTD and α-Syn on protein stability and binding affinity. Most of the interfacial mutations of CTD and α-Syn were found to destabilize the protein and reduced the protein binding affinity. The results thus shed light on the functional consequences of missense mutations observed in TDP-43 associated proteinopathies and may provide the mechanisms of co-morbidities involving these two proteins.Communicated by Ramaswamy H. Sarma.

Biology, Pathology, and Targeted Therapy of Exosomal Cargoes in Parkinson's Disease: Advances and Challenges

Parkinson's disease (PD) involves the loss of dopamine neurons and accumulation of alpha-synuclein (α-syn), leading to Lewy bodies. While α-syn-targeting immunotherapies show promise, clinical application is challenging. Emerging strategies include nano-platforms for targeted delivery and imaging, and cell-based therapies with patient-specific dopaminergic neurons, aiming to enhance treatment effectiveness despite challenges. Exosome-based methodologies are emerging as a promising area of research in PD due to their role in the spread of α-syn pathology. Exosomes are small extracellular vesicles that can carry misfolded α-syn and transfer it between cells, contributing to the progression of PD. They can be isolated from biological fluids such as blood and cerebrospinal fluid, making them valuable biomarkers for the disease. Additionally, engineering exosomes to deliver therapeutic agents, including small molecules, RNA, or proteins, offers a novel approach for targeted therapy, capitalizing on their natural ability to cross the blood-brain barrier (BBB). Ongoing studies are evaluating the safety and efficacy of these engineered exosomes in clinical settings. This review explores the role of exosomes in PD, focusing on their potential for diagnosis, treatment, and understanding of pathology. It highlights advancements and future directions in using exosomes as biomarkers and therapeutic tools.

SENP2-based N-terminal truncation of α-synuclein in Lewy pathology propagation

α-Synuclein (αSyn) is a major component of Lewy bodies (LBs) and Lewy neurites (LNs), which are pathological features of Parkinson's disease (PD) and dementia with Lewy bodies. In the PD brain, with disease progression, LB/LN formation is propagated from the lower brainstem to the cerebral cortex. Prion-like cell-to-cell seed transmission has been implicated as an underlying mechanism for Lewy-pathology propagation. However, the biochemical properties and production mechanism of those pathogenic seeds are unelucidated. In this study, we ascertained that the seeds released from pathological neurons that harbor LB/LN-like aggregates have the N-terminally truncated form of αSyn. This N-terminal truncation is directly catalyzed by SENP2, which is a well-known deSUMOylation enzyme. After SENP2 processing of recombinant αSyn, the SDS-resistant high-molecular oligomer formation was promoted in vitro. Inhibition of SENP2 activity suppressed aggregate formation and propagation in cultured neurons and mouse brains. Thus, SENP2 might be a therapeutic target in LB diseases.

Microglia-derived exosomal ciRS-7 mediates IL-17A effect of promoting neurodegeneration via miR-7 and SNCA targets in an experimental Parkinson's disease

Parkinson' s disease (PD) is a chronic neurodegenerative disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra (SN). Our research has demonstrated that the levels of interleukin (IL)-17A are elevated in the SN of rodent models of PD, and that IL-17A accelerates neurodegeneration in PD depending on microglial activation. Furthermore, existing studies indicate that exosomes released by activated microglia may play a significant role as mediators of neurodegeneration in PD. Herein, we demonstrated that BV-2-derived exosomes were taken up by ventral mesencephalic (VM) dopaminergic neurons, and mediated IL-17A effect of promoting dopaminergic neuronal injury. IL-17A-treated BV-2-derived exosomes altered neuronal miR-7 and SNCA expression and promoted dopaminergic neuronal injury in vitro. Inhibiting BV-2 exosome formation and secretion by GW4869 alleviated dopaminergic neuronal injury. Silencing ciRS-7 in BV-2 altered neuronal miR-7 and SNCA expression and mitigated dopaminergic neuronal injury. Overexpression of ciRS-7 in VM neurons altered neuronal miR-7 and SNCA expression and promoted dopaminergic neuronal injury. Injection with exosomes derived from IL-17A-treated BV-2 altered ciRS-7, miR-7 and SNCA expression in SN in MPTP-intoxicated mice and promoted nigrostriatal dopaminergic neurodegeneration and motor impairment. However, injection with exosomes derived from IL-17A and ciRS-7-shRNA treated BV-2 attenuates the manifestations mentioned above. These findings suggest that microglia-derived exosomal ciRS-7 mediates IL-17A effect of promoting neurodegeneration via miR-7 and SNCA targets and may provide a new paradigm to study the pathology of PD.

Exploring novel and potent glycogen synthase kinase-3β inhibitors through systematic drug designing approach

Significant implications of glycogen synthase kinase-3β (GSK-3β) have been reported in various neuronal disorders and malignant cancers. GSK-3β modulates diverse protein targets through phosphorylation, and its aberrant activity leads to neurological complications as well as tumour onset. Therefore, inhibiting GSK-3β activity through active-site fitting molecules may offer a favourable strategy for intercepting these disorders. This comprehensive study used multiple assays in tandem in order to explore the most potent GSK-3β inhibitor. Following structural similarity screening, 135 molecular docking and 135 standard MM-GBSA experiments were performed using AZD1080, a known inhibitor as standard. Among the 32 molecules demonstrating a stronger binding affinity than reference, only the two most potent molecules were chosen and their binding free energy was compared to AZD1080 using the Desmond trajectory clustering and eventual MM-GBSA. Additionally, the interaction status of these molecules and AZD1080 with GSK-3β was explored post-molecular dynamics. The stability of the strongest molecule (most potent) was evaluated in the active site of the above-mentioned kinase keeping its apo-form as reference. Notably, the e-Pharmacophores mapping was performed to address the level of complementarity of the most potent molecule and AZD1080 with the functional site of GSK-3β. Using various techniques, we identified the molecule with PubChem CID: 11167509 as the strongest molecule for obstructing GSK-3β, which may serve as a promising therapeutic after the meticulous evaluation on diverse models.

Neuronal constitutive endolysosomal perforations enable α-synuclein aggregation by internalized PFFs

Endocytosis, required for the uptake of receptors and their ligands, can also introduce pathological aggregates such as α-synuclein (α-syn) in Parkinson's Disease. We show here the unexpected presence of intrinsically perforated endolysosomes in neurons, suggesting involvement in the genesis of toxic α-syn aggregates induced by internalized preformed fibrils (PFFs). Aggregation of endogenous α-syn in late endosomes and lysosomes of human iPSC-derived neurons (iNs), seeded by internalized α-syn PFFs, caused the death of the iNs but not of the parental iPSCs and non-neuronal cells. Live-cell imaging of iNs showed constitutive perforations in ∼5% of their endolysosomes. These perforations, identified by 3D electron microscopy in iNs and CA1 pyramidal neurons and absent in non-neuronal cells, may facilitate cytosolic access of endogenous α-syn to PFFs in the lumen of endolysosomes, triggering aggregation. Inhibiting the PIKfyve phosphoinositol kinase reduced α-syn aggregation and associated iN death, even with ongoing PFF endolysosomal entry, suggesting that maintaining endolysosomal integrity might afford a therapeutic strategy to counteract synucleinopathies.

Investigating the protective properties of Panax ginseng and its constituents against biotoxins and metal toxicity: a mechanistic review

Natural toxins are toxic substances produced by living microorganisms and cause harmful effects to other creatures, but not the organisms themselves. Based on the sources, they are classified into fungal, microbial, herbal, algae, and animal biotoxins. Metals, the oldest toxicants, are not created or destroyed by human industry as elements, just concentrated in the biosphere. An antidote can counteract the toxic effects of a drug or toxin or mitigate the adverse effects of a harmful substance. The potential antidote effects of Panax ginseng in organ toxicity have been proved by many scientific research projects. Herein, we are going to gather a comprehensive mechanistic review of the antidotal effects of ginseng and its main constituents against natural toxins and metal toxicity. In this regard, a literate search has been done in PubMed/Medline, Science Direct, and Scopus from 2000 until 2024. The gathered data showed the protective impacts of this golden plant and its secondary metabolites against aflatoxin, deoxynivalenol, three-nitro propionic acid, ochratoxin A, lipopolysaccharide, nicotine, aconite, domoic acid, α-synuclein, amyloid β, and glutamate as well as aluminum, cadmium, chrome, copper, iron, and lead. These antidotal effects occur by multi-functional mechanisms. It may be attributed to antioxidant, anti-inflammatory, and anti-apoptotic effects. Future research directions on the antidotal effects of ginseng against natural toxins and metal toxicity involve broadening the scope of studies to include a wider range of toxins and metals, exploring synergistic interactions with other natural compounds, and conducting more human clinical trials to validate the efficacy and safety of ginseng-based treatments.

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.

mRNA Transcript Variants Expressed in Mammalian Cells

Gene expression or gene regulation studies often assume one gene expresses one mRNA. However, contrary to the conventional idea, a single gene in mammalian cells can express multiple transcript variants translated into several different proteins. The transcript variants are generated through transcription from alternative start sites and alternative post-transcriptional processing of the precursor mRNA (pre-mRNA). In addition, gene mutations and RNA editing further enhance the diversity of the transcript variants. The transcript variants can encode proteins with various domains, expanding the functional repertoire of a single gene. Some transcript variants may not encode proteins but function as non-coding RNAs and regulate gene expression. The expression level of the transcript variants may vary between cell types or within the same cells under different biological conditions. Transcript variants are characteristic of cell differentiation in a particular tissue, and the variants may play a key role in normal development and aging. Studies also reported that some transcript variants may have roles in disease pathogenesis. The biological significances urge studying the complexity of gene expression at the transcript level. This article updates the molecular basis of transcript variants in mammalian cells, including the formation mechanisms and potential roles in host biology. Gaining insight into the transcript variants will not only identify novel mechanisms of gene regulation but also unravel the role of the variants in health and disease.