Search Results (118)

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disorder, yet its pathogenic mechanisms remain incompletely understood, highlighting the need for reliable experimental models. We previously developed a murine model based on inhalation of a manganese mixture (MnCl₂ and Mn(OAc)₃), which reproduces dopaminergic neuron loss in the substantia nigra pars compacta (SNc) and motor impairment. However, its capacity to mimic mitochondrial dysfunction, a key mechanism in PD, had not been explored. This study evaluated mitochondrial ultrastructure, fission and fusion proteins, and the activity of electron transport chain complexes I and IV, alongside fine motor performance. Forty male CD1 mice were divided into control (deionized water) and manganese-exposed groups (0.04 M MnCl₂ + 0.02 M Mn(OAc)₃), inhaled for 1 h twice weekly over five months. Manganese inhalation induced significant fine motor deficits, increased mitochondrial number with reduced area and circularity, and disorganized cristae. Drp1 and Fis1 levels were elevated, accompanied by decreased activity of complexes I and IV, predominantly in the SNc. These findings demonstrate that this progressive, bilateral model reproduces mitochondrial and motor alterations resembling those observed in PD, supporting its utility for testing mitochondria-targeted therapeutic strategies. Full article

Background: The mirror neuron system (MNS) has been proposed as a key neural mechanism linking action perception, motor representation, and social cognition. This framework has increasingly been applied to pain research, encompassing pain empathy, observational learning of pain, and rehabilitative interventions such as mirror therapy. However, the literature is conceptually heterogeneous, methodologically diverse, and spans experimental, social, and clinical domains. Objective: This scoping review aims to map the extent, nature, and characteristics of the available evidence on the relationship between the MNS and pain, clarifying how MNS-related mechanisms are defined, investigated, and applied across different contexts. Methods: A scoping review was conducted using the methodological framework proposed by the Joanna Briggs Institute and reported in accordance with PRISMA-ScR guidelines. We searched PubMed/MEDLINE, Scopus, Web of Science, and PsycINFO. Studies were included if they addressed MNS-related mechanisms in pain processing, pain empathy, pain modulation, or pain rehabilitation. Eligible studies were charted and synthesized descriptively and thematically. Results: Twenty-one studies met the inclusion criteria. The evidence was predominantly derived from clinical and rehabilitative settings, with most studies focusing on mirror therapy or mirror visual feedback interventions. The majority of included populations consisting of adults with chronic pain conditions, particularly phantom limb pain and complex regional pain syndrome. Pain intensity, assessed mainly through self-reported clinical scales, was the most frequently reported outcome. A smaller number of studies investigated action observation or motor imagery paradigms, primarily in chronic musculoskeletal pain, showing short-term hypoalgesic effects. Across studies, substantial heterogeneity was observed in the conceptualization of MNS-related constructs, intervention protocols, outcome measures, and follow-up duration. Conclusions: Despite extensive theoretical discussion of the MNS, empirical applications are largely confined to clinical mirror-based interventions, with limited use of direct neurophysiological or neuroimaging markers. Since crucial conceptual and methodological gaps constrain comparability and translation into clinical practice, there is a need for clearer operational definitions and more integrated experimental and clinical research approaches. Full article

Zebrafish is emerging as a model animal for phenotype-based drug screening. Drugs screened from the zebrafish platform have advanced into clinical trials, underscoring their translational potential. Amyotrophic lateral sclerosis is a progressive motor neurons (MN) degenerative disease with few approved drugs. Previously, supplementation with exogenous recombinant phosphoglycerate kinase 1 (Pgk1) was found to improve MN growth through its interaction with receptor Eno2. To bypass the high complexity and cost of full-length Pgk1 production, a short segment within Pgk1 (M08) was predicted as the key motif interacting with Eno2, and a zebrafish phenotypic screening platform was established to find the most neurotrophic compound(s) among M08 and its mutants. We first found that M08-injected zebrafish embryos significantly increased branched caudal primary MNs (CaPMNs). However, compared to M08 (59.20 ± 1.80%), M039, among 17 mutants further screened, showed even more improvement of branched CaPMNs, up to 74.54 ± 3.73%. Next, when we administered the M039 peptide to C9ORF72-knockdown ALS-like zebrafish embryos, it improved axonal growth and swimming ability. Then, we employed a cellular model as a secondary screen, and M039 exhibited improved neurite outgrowth of MN (NOMN) and reduced p-Cofilin in NSC34 neural cells grown in ALS-like condition. Therefore, by using a zebrafish MN phenotype as a primary screening platform, we identified a mutated short peptide M039 having the most pronounced positive effect on improving neurite growth among all 17 mutants in comparison to parental M08, demonstrating the feasibility of zebrafish screening as a cost-effective strategy for finding promising neuroprotective short peptides that serve as neurotherapeutic potentials. Full article

Neuregulins (NRGs) are ligands of tyrosine kinase receptors from the ErbB family and play multiple developmental roles. NRG1–ErbB signaling regulates myelination and has been associated with amyotrophic lateral sclerosis (ALS) pathology. Given the potential therapeutic relevance of this pathway for motor neuron (MN) diseases, we employed a transgenic (TG) mouse with persistent neuronal overexpression of neuregulin type III (NRG1-III) to investigate its impact on the neuromuscular system. We performed an analysis of phenotypic changes in this TG model, including motor behavior, neuropathological evaluation by immunocytochemistry and ultrastructural examination of the spinal cord, peripheral nerves, and neuromuscular junctions (NMJs). Calcium dynamics in cultured MNs were also examined. We found that cholinergic C-boutons on TG MNs, where NRG1-III typically accumulates, exhibited upregulation of C-bouton-associated proteins and expansion of the subsynaptic cistern (SSC)-associated endoplasmic reticulum. Calcium imaging revealed altered homeostasis in TG MNs, accompanied by the upregulation of molecules linked to axonal plasticity. At NMJs, regressive changes involving autophagic dysregulation were observed. These alterations were accompanied by increased motor activity in behavioral tests. Overall, our findings indicate that persistently elevated NRG1-III signaling compromises MN connectivity and long-term health, a factor to consider when developing therapeutic strategies for neurodegenerative diseases such as ALS. Full article

5q-associated Spinal Muscular Atrophy (SMA) is a hereditary neuromuscular disorder caused by mutations in the survival of motor neuron 1 (SMN1) gene, leading to progressive muscle weakness, and atrophy. While traditionally viewed as a motor neuron (MN)-specific disease, emerging evidence highlights the critical role of astrocytes, particularly in regulating extracellular glutamate and mitigating MN toxicity. Here, we investigated astrocytic gap junctions with a focus on connexin 43 (Cx43). Using in vivo and in vitro approaches—including a late-onset SMA mouse model, human-derived astrocytes, and murine astrocyte cultures—we analyzed Cx43 expression and localization via genetic modification, immunostaining, Western blotting, and quantitative PCR. Functional consequences were assessed using ex vivo spinal cord slice cultures, Ca²⁺-imaging, and glutamate release assays. We found significant Cx43 upregulation in late-onset SMA mice, as well as in SMN-deficient murine and human-derived astrocytes. Increased Cx43 expression correlated with elevated astrocytic glutamate release and MN toxicity. Ca²⁺-imaging indicated Cx43-dependent mechanisms underlying this enhanced release. Pharmacological Cx43 inhibition with Gap27 reduced glutamate release and MN Ca²⁺ responses. These findings identify astrocytic Cx43 as a contributor to glutamate-mediated MN toxicity in late-onset SMA and support growing recognition of non-neuronal mechanisms in SMA pathology. Full article

Mutations in the gene encoding the p150 subunit of the dynactin complex (DCTN1) are linked to amyotrophic lateral sclerosis, spinal and bulbar muscular atrophy, and Perry syndrome. These neurodegenerative diseases can cause muscle weakness and atrophy, parkinsonian-like symptoms, and paralysis. To examine the evolution of neuropathology caused by a mutation in DCTN1 and cellular mechanisms of disease for therapeutic discovery, we characterized mice expressing either human wildtype or mutant (G59S) DCTN1. Neuron-specific expression of mutant, but not wildtype, DCTN1 caused fatal age-related paralytic disease and motor neuron (MN) degeneration in the spinal cord with axonopathy and chromatolysis without apoptotic morphology. MNs became positive for cleaved caspase-3, cleaved caspase-8, and nitrated Hsp90. Mitochondria accumulated and appeared fragmented and dysmorphic and then were lost. This pathology was accompanied by invasion of CD95- and CD8-positive mononuclear T cells into the ventral horn and accumulation of TNFα and IL9. Administration of the mitochondrial division inhibitor-1 (Mdivi-1) protected MNs and extended the lifespan of G59S-DCTN1 mice. A mitochondrial permeability transition pore inhibitor also extended lifespan. Thus, mutant DCTN1 causes degeneration of MNs associated with axonopathy, mitochondriopathy, nitrative stress, and caspase activation. It appears as retrograde neurodegeneration and inflammatory T-cell-like cytolysis. Mitochondria are possible therapeutic targets in DCTN1-linked neurodegenerative disorders. Full article

Background/Objectives: Approximately 20% of familial ALS (fALS) cases are linked to mutations in Cu/Zn superoxide dismutase (SOD1). Through a gain function, SOD1 misfolding exerts a toxic effect on motor neurons, leading to their degradation and ALS symptomology in both fALS cases and sporadic ALS (sALS) cases with no known genetic cause. To further our understanding of SOD1-ALS etiology, identifying motor neuron-specific SOD1 post-translational modifications (PTMs) and studying their structural influence is necessary. To this end, we have conducted a study on the influence of the deamidation of Asn53, a PTM proximal to key stabilizing motifs in SOD1, which has scarcely been addressed in the literature to date. Methods: Deamidation to N53 was identified by tandem mass spectrometry of SOD1 immunoprecipitated from motor neuron (MN) cultures derived from wild-type (WT) human induced pluripotent stem cells (iPSCs). WT SOD1 and N53D SOD1, a mutant mimicking the deamidation, were expressed in Escherichia coli and purified for in vitro analyses. Differences between species were measured by experiments probing metal cofactors, relative monomer populations, and aggregation propensity. Furthermore, molecular dynamics experiments were conducted to model and determine the influence of the PTM on SOD1 structure. Results: In contrast to WT, N53D SOD1 showed non-native incorporation of metal cofactors, coordinating more Zn²⁺ cofactors than total Zn-binding sites, and more readily adopted monomeric forms, unfolded, and aggregated with heating, possibly while releasing coordinated metals. Conclusions: Deamidation to N53 in SOD1 encourages the adoption of non-native conformers, and its detection in WT MN cultures suggests relevance to sALS pathophysiology. Full article

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder characterized by motor neuron (MN) degeneration, frequently overlapping with frontotemporal dementia (FTD). Protein aggregation is a hallmark of these disorders, yet the role of aggregates in ALS pathogenesis remains unclear. Previously, stomatin-like protein 2 (SLP2) and prohibitin (PHB) aggregates were identified in a model of CHCHD10-related ALS (Chchd10^S59L/+ mice). This study raises the question of the presence and possible involvement of these aggregates in ALS beyond CHCHD10-associated motor neuron disease (MND). Using immunohistofluorescence, we analyzed SLP2/PHB expression in the spinal MNs and hippocampus of two ALS mouse models: Fus^ΔNLS and Sod1^G86R. Additionally, post-mortem spinal cord tissues from 27 ALS and ALS-FTD patients were analyzed. SLP2/PHB aggregates were identified in spinal MNs and the hippocampus of Fus^ΔNLS mice but not in Sod1^G86R mice. In ALS patients, SLP2/PHB aggregation was observed in four cases, including two with C9ORF72 mutations. Interestingly, aggregates were absent in SOD1-associated ALS patients. These findings suggest that SLP2/PHB aggregation is not specific to CHCHD10 variants but may contribute to the pathogenesis of ALS from different origins. The age-related accumulation of these aggregates highlights their potential role in disease progression and as therapeutic targets. Future studies should investigate their mechanistic contributions across different ALS subtypes. Full article

Background/Objectives: Empathy is essential for successful social functioning, mediating different aspects of social cognition in everyday life. An intriguing aspect is the involvement of empathy even in basic neural mechanisms of action perception, thanks to its association with the Mirror Neuron System (MNS). The present retrospective study explores whether individual differences in cognitive and affective empathy, measured by the Interpersonal Reactivity Index (IRI) questionnaire, can predict motor resonance—the enhancement of motor cortex reactivity during the observation of biological movements—during transitive and intransitive action observation. Methods: Data from 160 healthy subjects who participated in transcranial magnetic stimulation (TMS) experiments assessing corticospinal excitability during action observation were retrospectively analyzed using multiple linear regression models. Participants filled the IRI and observed intransitive single-digit finger movements (n = 80) or grasping actions directed at different targets (intransitive, object-directed, social-directed; n = 80) synchronized with TMS over the primary motor cortex, allowing the investigation of how action features modulate the relationship between participants’ empathic traits and motor resonance magnitude. Results: Results show that empathic traits do not affect motor resonance during intransitive movements, whereas they do when motor resonance is measured during the observation of transitive actions. Cognitive empathy, particularly the perspective-taking scale, significantly predicts motor resonance magnitude when observing goal-directed actions. Meanwhile, affective empathy, specifically the empathic concern scale, predicts motor resonance while observing social action. Conclusions: These findings highlight that different facets of empathy are significantly related to humans’ ability to understand others’ actions through inner simulation mechanisms, particularly concerning action goals and social relevance. Full article

Retinoic acid (RA) binds RA (RAR) and Retinoid X (RXR) receptors to elicit biological effects by regulating transcription. RA is also known to have non-canonical activities mediated, primarily, by cellular retinoic acid-binding protein 1 (CRABP1) which forms protein complexes named “CRABP1 signalosomes” to regulate cytosolic signaling independent of RARs/RXRs. This review focuses on therapeutic applications in neurodegeneration by targeting CRABP1 signalosomes including CRABP1–MAPK, CRABP1–CaMKII, CRABP1–eIF2α, and others recently identified from our proteomic studies. The mouse Crabp1 gene is regulated by various epigenetic factors and is important for the health of multiple cell types including motor neurons (MNs). In humans, CRABP1 gene expression is reduced in ALS- and SMA-patient MNs. RA is a therapeutic agent for leukemias and dermatological disorders and is being investigated for managing neurodegenerative diseases, but its therapeutic effects are accompanied by RAR-mediated toxic effects. We have uncovered a novel class of synthetic retinoids that bind CRABP1 without acting on RARs, circumventing RAR-mediated toxic effects. These first-generation CRABP1-selective compounds C3, C4, and C32 target CRABP1–MAPK and/or CRABP1–CaMKII signalosomes. This knowledge, together with emerging structural information, sheds lights on the strategies in designing next-generation CRABP1-signalosome-selective retinoids for the management of neurodegenerative diseases. Full article

Amyotrophic lateral sclerosis (ALS) is a fatal type of neurodegenerative disease marked by progressive and selective degeneration of motor neurons (MNs) present in the spinal cord, brain stem and motor cortex. However, the intricate molecular mechanisms underlying primary cell death pathways, including ferroptosis-related genes (FRGs) mediating MN dysfunction in ALS, remain elusive. Ferroptosis, a novel type of iron-dependent cell death with the accumulation of lipid peroxidation products, stands distinct from apoptotic-related stress and other cell death mechanisms. Although growing advances have highlighted the role of iron deposition, apoptosis and alteration of antioxidant systems in ALS pathogenesis, there is little data at the systems biology level. Therefore, we performed a comprehensive bioinformatic analysis of bulk RNA-sequencing (RNA-seq) data by systematically comparing the gene expression profiles from iPSC-derived MNs of ALS patients and healthy controls using our datasets as well as from the GEO database to reveal the role of ferroptosis-related gene alterations in ALS, especially in selective MN vulnerability of FUSED IN SARCOMA (FUS) mutations. In this study, we first identified differentially expressed genes (DEGs) between FUS mutant and healthy controls. Subsequently, the crossover genes between DEGs and FRGs were selected as differentially expressed ferroptosis-related genes (DEFRGs). Functional enrichment and protein–protein interaction (PPI) analysis of DEFRGs identified that DNA damage, stress response and extra cellular matrix (ECM) were the most significantly dysregulated functions/pathways in FUS-ALS causing mutations compared to healthy controls. While GSEA analysis showed enrichment of genes associated with apoptosis, the degree of ferroptosis and iron ion homeostasis/response to iron of FUS MNs was lower. Altogether, our findings may contribute to a better understanding of the relevant role of cell death pathways underlying selective vulnerability of MNs to neurodegeneration in FUS-ALS pathophysiology. Full article

Metal exposure is a potential risk factor for amyotrophic lateral sclerosis (ALS). Increasing evidence suggests that elevated levels of DNA damage are present in both familial (fALS) and sporadic (sALS) forms of ALS, characterized by the selective loss of motor neurons in the brain, brainstem, and spinal cord. However, identifying and differentiating initial biomarkers of DNA damage response (DDR) in both forms of ALS remains unclear. The toxicological profiles from the Agency for Toxic Substances and Disease Registry (ATSDR) and our previous studies have demonstrated the influence of metal exposure-induced genotoxicity and neurodegeneration. A comprehensive overview of the ATSDR’s toxicological profiles and the available literature identified 15 metals (aluminum (Al), arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni), selenium (Se), uranium (U), vanadium (V), and zinc (Zn)) showing exposure-induced genotoxicity indicators associated with ALS pathogenesis. Genetic factors including mutations seen in ALS types and with concomitant metal exposure were distinguished, showing that heavy metal exposure can exacerbate the downstream effect of existing genetic mutations in fALS and may contribute to motor neuron degeneration in sALS. Substantial evidence associates heavy metal exposure to genotoxic endpoints in both forms of ALS; however, a data gap has been observed for several of these endpoints. This review aims to (1) provide a comprehensive overview of metal exposure-induced genotoxicity in ALS patients and experimental models, and its potential role in disease risk, (2) summarize the evidence for DNA damage and associated biomarkers in ALS pathogenesis, (3) discuss possible mechanisms for metal exposure-induced genotoxic contributions to ALS pathogenesis, and (4) explore the potential distinction of genotoxic biomarkers in both forms of ALS. Our findings support the association between metal exposure and ALS, highlighting under or unexplored genotoxic endpoints, signaling key data gaps. Given the high prevalence of sALS and studies showing associations with environmental exposures, understanding the mechanisms and identifying early biomarkers is vital for developing preventative therapies and early interventions. Limitations include variability in exposure assessment and the complexity of gene–environment interactions. Studies focusing on longitudinal exposure assessments, mechanistic studies, and biomarker identification to inform preventative and therapeutic strategies for ALS is warranted. Full article

Peripheral nervous system (PNS) neurons, including motor neurons (MNs), possess a remarkable ability to regenerate and reinnervate target muscles following nerve injury. This process is orchestrated by a combination of intrinsic neuronal properties and extrinsic factors, with Schwann cells (SCs) playing a central role. Upon injury, SCs transition into a repair phenotype that allows axonal regeneration through molecular signaling and structural guidance. However, the identity of the SCs’ reprogramming factors is only partially known. We previously identified hydrogen peroxide (H₂O₂) as an early and key driver of nerve repair, inducing gene expression rewiring in SCs to support nerve re-growth. In this study, we quantitatively assessed the role of H₂O₂ in the activation of key pro-regenerative signaling pathways in SCs following sciatic nerve compression, specifically the extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun, which are essential for functional nerve recovery. Notably, we found that H₂O₂ neutralization does not impact degeneration, but it significantly affects the regenerative response. Collectively, our findings establish H₂O₂ as a promising regulator of the Schwann cell injury response at the injury site, linking oxidative signaling to the molecular mechanisms governing nerve regeneration. Full article

Neuroinflammation is an inflammatory response occurring within the central nervous system (CNS). The process is marked by the production of pro-inflammatory cytokines, chemokines, small-molecule messengers, and reactive oxygen species. Microglia and astrocytes are primarily involved in this process, while endothelial cells and infiltrating blood cells contribute to neuroinflammation when the blood–brain barrier (BBB) is damaged. Neuroinflammation is increasingly recognized as a pathological hallmark of several neurological diseases, including amyotrophic lateral sclerosis (ALS), and is closely linked to neurodegeneration, another key feature of ALS. In fact, neurodegeneration is a pathological trigger for inflammation, and neuroinflammation, in turn, contributes to motor neuron (MN) degeneration through the induction of synaptic dysfunction, neuronal death, and inhibition of neurogenesis. Importantly, resolution of acute inflammation is crucial for avoiding chronic inflammation and tissue destruction. Inflammatory processes are mediated by soluble factors known as cytokines, which are involved in both promoting and inhibiting inflammation. Cytokines with anti-inflammatory properties may exert protective roles in neuroinflammatory diseases, including ALS. In particular, interleukin (IL)-10, transforming growth factor (TGF)-β, IL-4, IL-13, and IL-9 have been shown to exert an anti-inflammatory role in the CNS. Other recently emerging immune regulatory cytokines in the CNS include IL-35, IL-25, IL-37, and IL-27. This review describes the current understanding of neuroinflammation in ALS and highlights recent advances in the role of anti-inflammatory cytokines within CNS with a particular focus on their potential therapeutic applications in ALS. Furthermore, we discuss current therapeutic strategies aimed at enhancing the anti-inflammatory response to modulate neuroinflammation in this disease. Full article

The pathogenesis of neurodegenerative diseases results from the interplay between genetic and environmental factors. Aging and chronic oxidative stress are critical contributors to neurodegeneration. UBQLN2, a ubiquitin-related protein, aids in protein degradation and protects against oxidative stress. In ALS neurons harboring UBQLN2 mutations, oxidative stress accelerates pathological changes, yet the precise mechanisms remain unclear. Using induced motor neurons (iMNs) derived from UBQLN2 P497H iPSCs, we observed ALS-like phenotypes, including TDP-43 mislocalization, increased cell death, and reduced viability. Sodium arsenite (SA)-induced oxidative stress triggered stress granule formation, while autophagy dysfunction exacerbated neuronal degeneration. CHX and bosutinib treatments reduced ubiquitinated protein accumulation and alleviated degeneration, highlighting potential therapeutic pathways. These findings emphasize the role of chronic oxidative stress and stress granule formation in UBQLN2 ALS, offering insights into novel therapeutic targets. Full article