Neuronal Health Research Articles

Nonapoptotic role of EGL-1 in exopher production and neuronal health in Caenorhabditis elegans

Nonapoptotic role of EGL-1 in exopher production and neuronal health in Caenorhabditis elegans

Autophagy intersection: Unraveling the role of the SNARE complex in lysosomal fusion in Alzheimer's disease.

Autophagy is a fundamental cellular process critical for maintaining neuronal health, particularly in the context of neurodegenerative diseases such as Alzheimer's disease (AD). This review explores the intricate role of the SNARE complex in the fusion of autophagosomes with lysosomes, a crucial step in autophagic flux. Disruptions in this fusion process, often resulting from aberrant SNARE complex function or impaired lysosomal acidification, contribute to the pathological accumulation of autophagosomes and lysosomes observed in AD. We examine the composition, regulation, and interacting molecules of the SNARE complex, emphasizing its central role in autophagosome-lysosome fusion. Furthermore, we discuss the potential impact of specific SNARE protein mutations and the broader implications for neuronal health and disease progression. By elucidating the molecular mechanisms underlying SNARE-mediated autophagic fusion, we aim to highlight therapeutic targets that could restore autophagic function and mitigate the neurodegenerative processes characteristic of AD.

RNA dysregulation in neurodegenerative diseases.

Dysregulation of RNA processing has in recent years emerged as a significant contributor to neurodegeneration. The diverse mechanisms and molecular functions underlying RNA processing underscore the essential role of RNA regulation in maintaining neuronal health and function. RNA molecules are bound by RNA-binding proteins (RBPs), and interactions between RNAs and RBPs are commonly affected in neurodegeneration. In this review, we highlight recent progress in understanding dysregulated RNA-processing pathways and the causes of RBP dysfunction across various neurodegenerative diseases. We discuss both established and emerging mechanisms of RNA-mediated neuropathogenesis in this rapidly evolving field. Furthermore, we explore the development of potential RNA-targeting therapeutic approaches for the treatment of neurodegenerative diseases.

Astragaloside IV promotes neuronal axon regeneration by inhibiting the PTEN/AKT pathway.

Neuronal survival and regeneration are critical aspects of recovery from ischemic brain injuries. Astragaloside IV (AS-IV), a saponin extracted from the traditional Chinese medicine Astragalus membranaceus, has shown promise in promoting neuronal health. This study investigates the effects of AS-IV on neuronal survival and apoptosis post-oxygen-glucose deprivation (OGD), focusing on the modulation of the PTEN/AKT signaling pathway. Rat primary neuronal cells were isolated and subjected to OGD to simulate ischemic conditions. Afterwards, cells were treated with low and high doses of AS-IV. Neuronal viability and apoptosis were assessed using MTT and flow cytometry (FCM) assays. Immunofluorescence and Western blot analyses were performed to evaluate the expression of neuronal markers and proteins involved in the PTEN/AKT pathway. Post-OGD, neuronal cells exhibited decreased viability and increased apoptosis, which were significantly mitigated by AS-IV. Immunofluorescence showed enhanced Tuj1 expression, indicating increased neuronal purity and survival, enhanced NF200 expression, indicating increased axon lengths. FCM results revealed reduced apoptosis rates, particularly with higher doses of AS-IV. Western blot analysis confirmed inhibition of PTEN and activation of AKT, facilitating enhanced neuronal survival and axona regeneration. Additionally, overexpression of PTEN negated the anti-apoptotic effects of AS-IV, underscoring the critical role of the PTEN/AKT pathway in AS-IV mediated neuroprotection. AS-IV enhances neuronal survival and axona regeneration by modulating the PTEN/AKT pathway, highlighting its potential as a therapeutic agent for ischemic brain injuries. These findings suggest that targeting this pathway could be a strategic focus for developing effective neuroprotective therapies.

Neurotrophomodulatory effect of TNF-α through NF-κB in rat cortical astrocytes.

Tumor necrosis factor alpha (TNF-α) is a well-known pro-inflammatory cytokine originally recognized for its ability to induce apoptosis and cell death. However, recent research has revealed that TNF-α also plays a crucial role as a mediator of cell survival, influencing a wide range of cellular functions. The signaling of TNF-α is mediated through two distinct receptors, TNFR1 and TNFR2, which trigger various intracellular pathways, including NF-κB, JNK, and caspase signaling cascades. Both TNFR1 and TNFR2 are expressed in astrocytes, which are specialized glial cells essential for maintaining the structural and functional integrity of the central nervous system (CNS). Astrocytes support neuronal function by regulating brain homeostasis, maintaining synaptic function, and supplying metabolic substrates. In addition, astrocytes are known to secrete a variety of growth factors and neurotrophins, such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and NT-4/5. These neurotrophins play a critical role in supporting neuronal survival, synaptic plasticity, and myelination within the brain. The present study focuses on the role of TNF-α in modulating neurotrophin expression and secretion in rat cortical astrocytes. We demonstrate that TNF-α induces the upregulation of neurotrophins, particularly NGF and BDNF, in cultured astrocytes. This effect is accompanied by an increase in the expression of their respective receptors (TrkA & TrkB), further suggesting a functional modulation of neurotrophic signaling pathways. Notably, we show that the modulation of neurotrophin expression by TNF-α is mediated via the NF-κB signaling pathway. Additionally, we observed that TNF-α also regulates the secretion levels of NGF and BDNF into the culture media of astrocytes in a dose-dependent manner, indicating that TNF-α can modulate both the production and release of these growth factors. Taken together, our findings highlight a previously underexplored neuroprotective role of TNF-α in astrocytes. Specifically, we propose that TNF-α, through the upregulation of neurotrophins, may contribute to maintaining neuronal health and supporting neuroprotection under disease conditions.

Microfluidic Cultures of Basal Forebrain Cholinergic Neurons for Assessing Retrograde Cell Death by Live Imaging.

Neurons are highly polarized cells, with axons that may innervate distant target regions. In the brain, basal forebrain cholinergic neurons (BFCNs) possess extensive axons that project to several target regions such as the cortex, hippocampus, and amygdala, and may be exposed to a specific microenvironment in their axon targets that may have retrograde effects on neuronal health. Interestingly, BFCNs express the pan-neurotrophin receptor p75NTR throughout life while also concomitantly co-expressing all Trk receptors, making them capable of responding to both mature and precursor neurotrophins to promote survival or apoptosis, respectively. Levels of these trophic factors may be modulated in the BFCN axon or soma microenvironment under neurodegenerative conditions such as seizure and brain injury. In this protocol, BFCNs are established in microfluidic devices for compartmental culture, with the aim of studying the effects of axon- or soma-specific stimulation of BFCNs for an in vitro representation of distal axon vs. soma environments as seen in vivo. This study further establishes a novel method of tracing and imaging live BFCNs exposed to stimuli in their distal axons with the aim of assessing retrograde cell death. The in vitro compartmental culture system of BFCNs that allows live imaging may be applied to investigate various effects of axon- or soma-specific stimuli that affect BFCN health, maintenance, and death, to model events that occur in the context of brain injury and neurodegenerative disorders. Key features • Separation of axons and soma of basal forebrain primary neurons in vitro using microfluidic chambers. • Compartmental/localized treatment of axons or somas of BFCNs. • Live imaging of retrogradely labeled BFCNs to assess cell death.

Altered lipid profile and reduced neuronal support in human induced pluripotent stem cell-derived astrocytes from adrenoleukodystrophy patients.

X-linked adrenoleukodystrophy (ALD) is a peroxisomal disorder resulting from pathogenic variants in the ABCD1 gene that primarily affects the nervous system and is characterized by progressive axonal degeneration in the spinal cord and peripheral nerves and leukodystrophy. Dysfunction of peroxisomal very long-chain fatty acid (VLCFA) degradation has been implicated in ALD pathology, but the impact on astrocytes, which critically support neuronal function, remains poorly understood. Fibroblasts from four ALD patients were reprogrammed to generate human-induced pluripotent stem cells (hiPSC). hiPSC-derived astrocytes were generated to study the impact of ALD on astrocytic fatty acid homeostasis. Our study reveals significant changes in the lipidome of ALD hiPSC-derived astrocytes, characterized by an enrichment of VLCFAs across multiple lipid classes, including triacylglycerols, cholesteryl esters, and phosphatidylcholines. Importantly, ALD hiPSC-derived astrocytes not only exhibit intrinsic lipid dysregulation but also affect the dendritic tree complexity of neurons in co-culture systems. These findings highlight the cell-autonomous effects of pathogenic variants in the ABCD1 protein on astrocytes and their microenvironment, shed light on potential mechanisms underlying ALD neuropathology, and underscore the critical role of astrocytes in neuronal health.

Neuroprotective Efficacy and Complementary Treatment with Medicinal Herbs: A Comprehensive Review of Recent Therapeutic Approaches in Epilepsy Management.

Central Nervous System (CNS) disorders affect millions of people worldwide, with a significant proportion experiencing drug-resistant forms where conventional medications fail to provide adequate seizure control. This abstract delves into recent advancements and innovative therapies aimed at addressing the complex challenge of CNS-related drug-resistant epilepsy (DRE) management. The idea of precision medicine has opened up new avenues for epilepsy treatment. Herbs such as curcumin, ginkgo biloba, panax ginseng, bacopa monnieri, ashwagandha, and rhodiola rosea influence the BDNF pathway through various mechanisms. These include the activation of CREB, inhibition of NF-κB, modulation of neurotransmitters, reduction of oxidative stress, and anti- inflammatory effects. By promoting BDNF expression and activity, these herbs support neuroplasticity, cognitive function, and overall neuronal health. Novel antiepileptic drugs (AEDs) with distinct mechanisms of action demonstrate efficacy in refractory cases where traditional medications falter. Additionally, repurposing existing drugs for antiepileptic purposes presents a cost-effective strategy to broaden therapeutic choices. Cannabidiol (CBD), derived from cannabis herbs, has garnered attention for its anticonvulsant properties, offering a potential adjunctive therapy for refractory seizures. In conclusion, recent advances and innovative therapies represent a multifaceted approach to managing drug-resistant epilepsy. Leveraging precision medicine, neurostimulation technologies, novel pharmaceuticals, and complementary therapies, clinicians can optimize treatment outcomes and improve the life expectancy of patients living with refractory seizures. Genetic testing and biomarker identification now allow for personalized therapeutic approaches tailored to individual patient profiles. Utilizing next-generation sequencing techniques, researchers have elucidated genetic mutations.

Effects of Age and Atomoxetine on Olfactory Perception and Learning and Underlying Plasticity Mechanisms in Rats.

The locus coeruleus (LC) plays a vital role in cognitive function through norepinephrine release. Impaired LC neuronal health and function is linked to cognitive decline during ageing and Alzheimer's disease. This study investigates age-related alterations in olfactory detection and discrimination learning, along with its reversal, in Long-Evans rats, and examines the effects of atomoxetine (ATM), a norepinephrine uptake inhibitor, on these processes. Adult (6-9 months) and aged (22-24 months) Long-Evans rats underwent odour detection threshold experiments with saline and two doses of ATM (0.3 and 1 mg/kg). Reward-based odour discrimination learning included simple, difficult and reversal learning tasks. LC neuron density, dopamine beta-hydroxylase and norepinephrine transporter expression in the piriform cortex (PC) and orbitofrontal cortex were measured. Reversal learning and olfactory threat extinction were used to measure behavioural flexibility. Immunohistochemistry and western blotting were used to analyse phosphorylated cAMP response element binding protein (pCREB) and cFos expression and exvivo electrophysiology assessed long-term depression (LTD) in the PC. Whereas adult and aged cohorts showed similar odour detection and discrimination learning, fewer aged rats acquired reversal learning successfully. ATM improved reward-based odour discrimination in adults but hindered learning reversal. A delayed CREB phosphorylation in the posterior PC associated with atomoxetine administration possibly underlies learning enhancement. ATM resulted in less freezing behaviour in a threat conditioning and extinction paradigm at moderate, but not at higher doses. ATM administration exvivo prevented PC LTD. These findings highlight the intricate effects of atomoxetine, influenced by target structures, and suggest potential interactions with other neurotransmitters. Our results contribute to understanding the impact of ageing and norepinephrine enhancers on cognitive processes.

Astrocytic Gap Junctions protein Cx43/Cx30 modulate EAAT1 and glutamate to mediate cerebral ischemia–reperfusion injury

The gap connexins of astrocytes play a crucial role in facilitating neuronal coordination and maintaining the homeostasis of the central nervous system. Cx30/Cx43 are the main proteins constituting these gap junctions, and the glutamate transporter EAAT1 associates with nerve injury. However, the role and mechanism underlying the changes of astrocytic connexins and EAAT1 during cerebral ischemia–reperfusion injury remain unclear. In this study, we investigated the expressions of Cx30, Cx43, and EAAT1 in OGD/R-treated astrocytes and in a MCAO/R animal model using gap junction inhibitors and siRNAs targeting Cx43 and Cx30. The differences of cell viability, malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), reactive oxygen species (ROS) and glutamate in cells and tissues were detected. Our results indicate that OGD/R exposure leads to the decline of astrocyte activity, which, in turn, adversely affects neuronal health. Ischemia-reperfusion induced increasing Cx43 and EAAT1 expression and decreasing Cx30 expression in astrocytes and animal brain tissue. Moreover, ischemia–reperfusion resulted in heightened MDA and ROS levels and reduced CAT and SOD activities in both astrocytes and the surrounding brain tissue. The release of glutamate from astrocytes and its concentration in animal brain tissue significantly increased following ischemia–reperfusion. Inhibition Cx43 expression through Gap26 or siRNA effectively mitigated the increase in EAAT1 and glutamate levels, as well as the oxidative stress changes induced by ischemia–reperfusion. Therefore, Brain astrocytes may mediate the effects of cerebral ischemia–reperfusion injury by influencing glutamate transporters and glutamate dynamics in response to oxidative stress through Cx30/Cx43.

Disruptions in cellular communication: Molecular interplay between glutamate/NMDA signalling and MAPK pathways in neurological disorders.

Neurological disorders significantly impact the central nervous system, contributing to a growing public health crisis globally. The spectrum of these disorders includes neurodevelopmental and neurodegenerative diseases. This manuscript reviews the crucial roles of cellular signalling pathways in the pathophysiology of these conditions, focusing primarily on glutaminase/glutamate/NMDA receptor signalling, alongside the mitogen-activated protein kinase (MAPK) pathways-ERK1/2, C-JNK, and P38 MAPK. Activation of these pathways is often correlated with neuronal excitotoxicity, apoptosis, and inflammation, leading to many other pathological conditions such as traumatic brain injury, stroke, and brain tumor. The interplay between glutamate overstimulation and MAPK signalling exacerbates neurodegenerative processes, underscoring the complexity of cellular communication in maintaining neuronal health. Dysfunctional signalling alters synaptic plasticity and neuronal survival, contributing to cognitive impairments in various neurological diseases. The manuscript emphasizes the potential of targeting these signalling pathways for therapeutic interventions, promoting neuroprotection and reducing neuroinflammation. Incorporating insights from precision medicine and innovative drug delivery systems could enhance treatment efficacy. Overall, understanding the intricate mechanisms of these pathways is essential for developing effective strategies to mitigate the impact of neurological disorders and improve patient outcomes. This review highlights the necessity for further exploration into these signalling cascades to facilitate advancements in therapeutic approaches, ensuring better prognoses for individuals affected by neurological conditions.

Epidermal Collagen Reduction Drives Selective Aspects of Aging in Sensory Neurons.

Despite advances in understanding molecular and cellular changes in the aging nervous system, the upstream drivers of these changes remain poorly defined. Here, we investigate the roles of non-neural tissues in neuronal aging, using the cutaneous PVD polymodal sensory neuron in Caenorhabditis elegans as a model. We demonstrate that during normal aging, PVD neurons progressively develop excessive dendritic branching, functionally correlated with age-related proprioceptive deficits. Our study reveals that decreased collagen expression, a common age-related phenomenon across species, triggers this process. Specifically, loss-of-function in dpy-5 or col-120, genes encoding cuticular collagens secreted to the epidermal apical surface, induces early-onset excessive dendritic branching and proprioceptive deficits. Adulthood-specific overexpression of dpy-5 or col-120 mitigates excessive branching in aged animals without extending lifespan, highlighting their specific roles in promoting neuronal health span. Notably, collagen reduction specifically drives excessive branching in select sensory neuron subclasses but does not contribute to PVD dendritic beading, another aging-associated neurodegenerative phenotype associated with distinct mechanosensitive dysfunction. Lastly, we identify that rig-3, an immunoglobulin superfamily member expressed in interneurons, acts upstream of collagen genes to maintain PVD dendritic homeostasis during aging, with collagen's regulatory role requiring daf-16/FOXO. These findings reveal that age-related collagen reduction cues neuronal aging independently of collagen's traditional structural support function, possibly involving bi-directional communication processes between neurons and non-neuronal cells. Our study also offers new insights into understanding selective neuron vulnerability in aging, emphasizing the importance of multi-tissue strategies to address the complexities of neuronal aging.

Astrocytes contribute to toll-like receptor 2-mediated neurodegeneration and alpha-synuclein pathology in a human midbrain Parkinson’s model

BackgroundParkinson’s disease (PD) is characterised by degeneration of ventral midbrain dopaminergic (DA) neurons and abnormal deposition of α-synuclein (α-syn) in neurons. Activation of the innate immune pathogen recognition receptor toll-like receptor 2 (TLR2) is associated with exacerbation of α-syn pathology. TLR2 is increased on neurons in the PD brain, and its activation results in the accumulation and propagation of α-syn through autophagy inhibition in neurons. In addition to the aggregation and propagation of pathological α-syn, dysfunction of astrocytes may contribute to DA neuronal death and subsequent clinical progression of PD. However, the role of astrocytes in TLR2-mediated PD pathology is less explored but important to address, given that TLR2 is a potential therapeutic target for PD.MethodsInduced pluripotent stem cells from three controls and three PD patients were differentiated into a midbrain model comprised of neurons (including DA neurons) and astrocytes. Cells were treated with or without the TLR2 agonist Pam3CSK4, and α-syn pathology was seeded using pre-formed fibrils. Confocal imaging was used to assess lysosomal function and α-syn pathology in the different cell types, as well as DA neuron health and astrocyte activation.ResultsTLR2 activation acutely impaired the autophagy lysosomal pathway, and potentiated α-syn pathology seeded by pre-formed fibrils in PD neurons and astrocytes, leading to degeneration and loss of DA neurons. The astrocytes displayed impaired chaperone-mediated autophagy reducing their ability to clear accumulated α-syn, and increases of A1 neurotoxic phenotypic proteins SerpinG1, complement C3, PSMB8 and GBP2. Moreover, the phenotypic changes in astrocytes correlated with a specific loss of DA neurons.ConclusionsTaken together, these results support a role for astrocyte dysfunction in α-syn accumulation and DA neuronal loss following TLR2 activation in PD.

Centella asiatica Promotes Antioxidant Gene Expression and Mitochondrial Oxidative Respiration in Experimental Autoimmune Encephalomyelitis.

Background/Objectives:Centella asiatica (L.) Urban (family Apiaceae) (C. asiatica) is a traditional botanical medicine used in aging and dementia. Water extracts of C. asiatica (CAW) have been used to treat neuropsychiatric symptoms in related animal models and are associated with increases in antioxidant response element (ARE) genes and improvements in mitochondrial respiratory function and neuronal health. Because multiple sclerosis (MS) shares its neurogenerative pathology of oxidative stress and mitochondrial dysfunction with aging and dementia, neuropsychiatric symptoms in MS may also benefit from C. asiatica. To determine whether CAW similarly benefits neuropsychiatric symptoms, ARE gene expression, and mitochondrial respiration in inflammatory models of MS, and to determine the effects of CAW on clinical disability and inflammation, we tested CAW using experimental autoimmune encephalomyelitis (EAE). Methods: C57BL/6J mice induced with EAE were treated with CAW or a placebo for 2 weeks. The outcomes were clinical disability, signs of anxiety (open field test), ARE gene expression, mitochondrial respiration, and inflammation and demyelination. Results: At the dosing schedule and concentrations tested, CAW-treated mice with EAE demonstrated increased ARE gene expression and mitochondrial respiratory activity compared to those of placebo-treated mice with EAE. CAW was also associated with reduced inflammatory infiltrates in the spinal cord, but the differences between the populations of activated versus quiescent microglia were equivocal. CAW did not improve behavioral performance, EAE motor disability, or demyelination. Conclusions: In the inflammatory EAE model of MS, CAW demonstrates similar neuroprotective effects to those it exhibits in aging and dementia mouse models. These benefits, along with the anti-inflammatory effects of CAW, support further investigation of its neuropsychiatric effects in people with MS.

Microglia balances hypermyelination and demyelination in the brain.

Myelin is crucial for neuron health and central nervous system (CNS) function. Recent research by McNamara etal. highlighted microglia's essential role in compacting the myelin sheath during development and their absence leads to aberrant oligodendrocyte clusters and subsequent cognitive impairment. The study revealed that the critical involvement of the TGFβ1-TGFβR1 axis in microglia-oligodendrocyte communication could influence the oligodendrocyte lipid metabolism and thereby regulate myelin integrity. Further exploration is needed to fully elucidate the dual impact of microglia on myelination, and interactions with other glial cells, holding promise for discovering new targets in myelin-related neurodegenerative and CNS disorders.

Clearing Amyloid-Beta by Astrocytes: The Role of Rho GTPases Signaling Pathways as Potential Therapeutic Targets.

Astrocytes, vital support cells in the central nervous system (CNS), are crucial for maintaining neuronal health. In neurodegenerative diseases such as Alzheimer's disease (AD), astrocytes play a key role in clearing toxic amyloid-β (Aβ) peptides. Aβ, a potent neuroinflammatory trigger, stimulates astrocytes to release excessive glutamate and inflammatory factors, exacerbating neuronal dysfunction and death. Recent studies underscore the role of Rho GTPases-particularly RhoA, Rac1, and Cdc42-in regulating Aβ clearance and neuroinflammation. These key regulators of cytoskeletal dynamics and intracellular signaling pathways function independently through distinct mechanisms but may converge to modulate inflammatory responses. Their influence on astrocyte structure and function extends to regulating endothelin-converting enzyme (ECE) activity, which modulates vasoactive peptides such as endothelin-1 (ET-1). Through these processes, Rho GTPases impact vascular permeability and neuroinflammation, contributing to AD pathogenesis by affecting both Aβ clearance and cerebrovascular interactions. Understanding the interplay between Rho GTPases and the cerebrovascular system provides fresh insights into AD pathogenesis. Targeting Rho GTPase signaling pathways in astrocytes could offer a promising therapeutic approach to mitigate neuroinflammation, enhance Aβ clearance, and slow disease progression, ultimately improving cognitive outcomes in AD patients.

Caliber of sensory axons in vivo varies spatially and temporally and is influenced by the cellular microenvironment.

Axon caliber directly influences how quickly neurons send messages to other cells and likely plays a role in the overall health of neurons. In the peripheral nervous system, where neurons cover particularly long distances, cell shape can determine whether an animal successfully executes behaviors such as an escape response. We found that axon caliber can vary between locations within the same cell, and that it is highly dynamic. Taking these variations into account may allow neuroscientists to better estimate transmission speeds for cells in neural circuits. Additionally, we found that axon caliber is distorted when nearby cells change their shape. Thus, the cellular microenvironment is one of potentially many contributors to caliber dynamics, broadening our view of axon caliber determinants.

Dysregulation of protein degradation and alteration of secretome in α-synuclein-exposed astrocytes: implications for dopaminergic neuronal dysfunction

BackgroundA key factor in the propagation of α-synuclein pathology is the compromised protein quality control system. Variations in membrane association and astrocytic uptake between different α-synuclein forms suggest differences in exocytosis or membrane cleavage, potentially impacting the secretome's influence on dopaminergic neurons. We aimed to understand differences in protein degradation mechanisms of astrocytes for both wild-type (WT) and mutant forms of α-synuclein, specifically during periods of reduced degradation efficiency. We also investigated α-synuclein release into the secretome and its effects on healthy dopaminergic neurons.MethodsCellular models used were rat primary astrocytes alongside hiPSC-derived astrocytes, whose impact on rat primary dopaminergic neurons and the human SH-SY5Y cell line was investigated. We examined the release and accumulation of α-synuclein resulting from impaired degradatory pathways, including matrix metalloprotease-MMP9, the ubiquitin proteasomal pathway-UPS, and the autophagy-lysosomal pathway-ALP, using immunocytochemical analysis and flow cytometry. Additionally, we explored the effect of astrocytic secretome on dopaminergic-neuronal survival, neurite collapse and function.ResultsAt early stages, astrocytes were able to deal efficiently with monomeric α-synuclein (via UPS), and larger aggregates (through MMP9 and autophagy), clearing extracellular α-synuclein and maintaining neuronal health. However, extended exposure to extracellular monomeric and aggregated α-synuclein compromised their proteasomal activity, inhibiting MMP9 and destabilizing autophagy, transforming astrocytes from protectors to promoters of neurodegeneration. This study is the first to elucidate the astrocytes' preferred degradation pathways for both monomeric and aggregated forms of α-synuclein, along with the subsequent effects of these payloads on the cellular degradation machinery. The astrocytic transformation is characterized by α-synuclein expulsion, increased release of inflammatory cytokines, and diminished secretion of growth factors leading to dopaminergic neuronal apoptosis and dysfunction, particularly neurite collapse, intracellular Ca2+ response and vesicular dopamine release. The presence of phosphorylated and nitrated α-synuclein species in astrocytes also suggests their potential involvement in modifying both forms of the protein.ConclusionThe initial protective action of astrocytes in clearing and degrading extracellular α-synuclein is severely compromised at latter stages, leading to astrocytic dysfunction and impairing neuron-glia cross-talk. This study underscores the criticality of integrating astrocytes into treatment paradigms in synucleinopathies.

Unraveling the Role of SSH1 in Chronic Neuropathic Pain: A Focus on LIMK1 and Cofilin Dephosphorylation in the Prefrontal Cortex.

Neuropathic pain, a debilitating condition stemming from nervous system injuries, has profound impacts on quality of life. The medial prefrontal cortex (mPFC) plays a crucial role in the modulation of pain perception and emotional response. This study explores the involvement of Slingshot Homolog 1 (SSH1) protein in neuropathic pain and related emotional and cognitive dysfunctions in a mouse model of spared nerve injury (SNI). SNI was induced in C57BL/6J mice. SSH1's role was investigated via its overexpression and knockdown using lentiviral vectors in the mPFC. Behavioral assays (thermal and mechanical allodynia, open field test, elevated plus maze, tail suspension test, Y-maze, and novel object recognition were conducted to assess pain sensitivity, anxiety, depression, and cognitive function. Tissue samples underwent Hematoxylin and Eosin staining, Western blotting, immunofluorescence, co-immunoprecipitation, and enzyme-linked immunosorbent assay for inflammatory markers. SNI mice displayed significant reductions in neuronal density and dendritic integrity in the mPFC, alongside heightened pain perception and emotional disturbances, as compared to sham controls. Overexpression of SSH1 ameliorated these alterations, improving mechanical and thermal thresholds, reducing anxiety and depressive behaviors, and enhancing cognitive performance. Conversely, SSH1 knockdown exacerbated these phenotypes. Molecular investigations revealed that SSH1 modulates pain processing and neuronal health in the mPFC partially through the dephosphorylation of Cofilin and LIM domain kinase 1 (LIMK1), as evidenced by changes in their phosphorylation states and interaction patterns. SSH1 plays a pivotal role in the modulation of neuropathic pain and associated neuropsychological disturbances in the mPFC of mice. Manipulating SSH1 expression can potentially reverse the neurophysiological and behavioral abnormalities induced by SNI, highlighting a promising therapeutic target for treating neuropathic pain and its complex comorbidities.

Mitochondrial replenishment as a treatment for Alzheimer’s Disease

AbstractBackgroundFindings have demonstrated that mitochondrial dysfunction is vital to Alzheimer’s Disease (AD) pathogenesis and progression. This study explored an innovative treatment strategy involving transfer of polymer‐functionalized, healthy mitochondria to AD neurons. We hypothesized that this organelle transplantation approach would restore mitochondrial function and bioenergetics, preventing aberrant neuronal dynamics associated with AD.MethodNeuronal cells (SH‐SY5Y) were stimulated with amyloid‐β (Aβ1‐42). Mitochondria were functionalized with dextran‐triphenylphosphonium (Dex‐TPP/Mt) and administered to neurons. Internalization of Dex‐TPP/Mt was assessed, as was the effect of mitochondrial transfer on Aβ‐treated SH‐SY5Y cell ROS levels, mitochondrial membrane potential, mitochondrial dynamics, ATP levels, and apoptosis.ResultDex‐TPP/Mt underwent efficient internalization into Aβ‐treated SH‐SY5Y cells. The treatment reduced intracellular ROS levels and restored mitochondrial membrane potential. Mitochondrial quality control was also re‐established, as mitochondrial fusion and fission processes were balanced and mitophagy reduced. Dex‐TPP/Mt treated neurons also increased ATP levels. Notably, mitochondrial transfer modulated the Bax/Bcl‐2 ratio, inhibited caspase‐3 activation, and suppressed the pJNK pathway, highlighting reduced neuronal apoptosis that was confirmed by Annexin V assay.ConclusionMitochondrial transfer has potential as a therapeutic approach for AD. The treatment highlighted herein effectively mitigated the impact of Aβ on neuronal health by targeting mitochondrial dysfunction and oxidative stress. This opens several avenues for similar strategies aimed at addressing dysregulated bioenergetics and mitochondrial dynamics in AD.