Exocytosis Research Articles (Page 1)

Endogenous opioid peptides have been linked to numerous physiological functions, including pain perception and the motivational drive associated with substance use disorders, but many fundamental aspects of transmission remain ambiguous. The kinetics of endogenous opioid peptides are thought to be slower and to last longer than those of more classical small-molecule neurotransmitters, like dopamine; however, a direct comparison of the release and diffusive spread of these molecules in the brain is lacking. Here, fast-scan cyclic voltammetry was coupled with carbon microelectrodes for co-detection of dopamine and met-enkephalin at single recording sites in rat striatal slices. The measurements used a voltammetric waveform that was specifically designed to minimize sensitivity to dopamine, maximize sensitivity to enkephalin, and minimize biofouling. Both neurotransmitter (dopamine) and neuropeptide (met-enkephalin, M-ENK) release scaled with stimulation duration. Interestingly, ENK dynamics in striatum displayed a unique biphasic profile with a significant latency to peak that occurred ∼30 s after stimulation, suggesting a sphere of influence that was ∼3x larger than that of dopamine. Mathematical modeling of the evoked M-ENK concentration profile suggests that multiple forms of ENK were released at once, such that some of the five-amino-acid form of M-ENK was released in exocytosis, and some was generated in the extracellular space by enzymatic cleavage of a larger form of ENK. Finally, a series of experiments combined solid-phase extraction with liquid-chromatography mass spectrometry to independently verify ENK release. The findings provide direct evidence to support widely held assumptions regarding neuropeptide release, and they demonstrate how different classes of signaling molecules can potentially affect distinct cellular populations in striatum─even when released at the same site.

Ca²⁺ signaling is essential for neuronal development, migration, synaptic activity, spine plasticity, neurotransmitter release, membrane excitability, and long-term synaptic plasticity, as well as for the coupling between membrane depolarization and downstream signaling. Traditionally, Plasma Membrane Ca²⁺ ATPases (PMCAs) were considered high-affinity, low-capacity calcium extruders. However, recent evidence reveals that the PMCA-Neuroplastin complex facilitates ultrafast Ca²⁺ clearance at kilohertz frequencies, reshaping our understanding of calcium regulation, in particular in neurons. For bulk Ca²⁺ clearance, they are overshadowed by more powerful low-affinity/high-capacity systems on the plasma membrane. This raises key questions: what is the specific physiological and pathological role of PMCAs? Why do cells require a high-affinity/low-capacity, ATP-dependent extrusion mechanism? What is the functional meaning of the diversity of isoforms (four) and splice variants (over thirty)? And why do neurons localize distinct PMCA pumps to pre- and postsynaptic sites? The prevailing hypothesis is that PMCAs fine-tune Ca²⁺ microdomains through local regulation and interactions with specific protein partners. Finally, understanding their role in Purkinje cells (PCs) is particularly relevant, as alterations in PMCA function have been implicated in cerebellar pathology and ataxia.

Botulinum neurotoxins (BoNTs) are the bacterial proteins responsible for the flaccid paralysis and lethal effects of botulism. They act by inhibiting neurotransmitter release, primarily at peripheral cholinergic nerve terminals, and have traditionally been classified into seven serotypes, designated with letters A through G. Over a long history of investigation, scientists and physicians have learned to harness the selectivity and potency of these neurotoxins to advance therapeutic applications. These advances have come by leveraging the basic science understanding of how the BoNT's work. The BoNTs are typically produced as inactive single-chain proteins of 150kDa that can be proteolytically activated to form a 50kDa light chain (LC) and 100kDa heavy chain (HC) that remain linked by a disulfide bond. The BoNTs act through a multi-step mechanism in which the HC mediates receptor binding and translocation of the LC into the neuronal cell cytosol. The LC is a zinc endopeptidase and each BoNT serotype cleaves a unique and specific bond within the three-protein soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex. In the late 1990s, I had the opportunity to help visualize the atomic structure of this formidable molecule, a story I share to honor the legacy of Hans Bigalke, whose work set the stage for new careers and discoveries in BoNT research and medicine.

Amyloid-β (Aβ) is recognized as a pathological hallmark of Alzheimer's disease, but accumulating evidence suggests that it also serves physiological roles in the healthy brain. Notably, Aβ secretion is tightly linked to neuronal activity and wakefulness, and its clearance is facilitated by sleep, raising the possibility that Aβ regulates sleep homeostasis. We propose that Aβ functions as a cytokine-like somnogen: a molecule whose accumulation during wakefulness promotes sleep onset and maintenance via synaptic and immune mechanisms. This framework reframes Aβ not as a toxic byproduct but as a key intermediary between neural activity and restorative sleep processes. We synthesize findings from molecular biology, electrophysiology, animal models, and human sleep studies, including research on AβPP processing, activity-dependent Aβ release, oligomeric signaling, and the effects of anti-amyloid therapies on sleep. Particular emphasis is placed on evidence that Aβ modulates synaptic excitability, engages glial immune pathways, and fulfills formal criteria for cytokine classification. Across multiple systems, Aβ exhibits properties consistent with homeostatic downscaling: it dampens neurotransmitter release, suppresses excitatory receptor trafficking, and activates sleep-promoting neuronal populations. Disruption of endogenous AβPP cleavage impairs sleep consolidation, while depletion of Aβ can lead to network hyperexcitability and disturbed sleep. Post-marketing reports of insomnia and abnormal dreams with plaque-clearing agents further support a physiological role. Recognizing Aβ as a somnogen offers a unifying model for sleep disruption in AD and raises caution about therapies that neutralize Aβ indiscriminately. Future interventions may benefit from preserving Aβ's homeostatic roles while mitigating its pathological aggregation.

Background: Hyperactivity of sympathetic neurons in the stellate ganglia (SG) contributes to ventricular arrhythmias (VAs) and remodeling post-myocardial infarction (MI). However, the role of satellite glial cells (SGCs) surrounding the neurons in this process remains unknown. Methods: SGC-specific chemogenetic manipulation was locally applied to modulate SG-SGC activity dual-directionally in the rats with naïve or infarcted hearts. Subsequently, cardiac sympathetic neural activity, ventricular electrophysiological stability in response to stimulation were evaluated, as well as cardiac neural and structural remodeling post-MI. SG bulk RNA sequencing and the interaction between SGCs and sympathetic neurons isolated from SG were employed to explore the underpinning mechanisms. Results: SG-SGC excitation increased SG neural activity and ventricular electrophysiological instability in rats with naïve hearts whereas its inhibition influenced none of the above under physiological condition. Of note, 2h-MI provoked SG-SGC activation that positively correlated to cardiac sympathetic neurotransmitter (norepinephrine) release. Accordingly, SGC activation in the SG enhanced cardiac sympathetic hyperactivity 2h post-MI while SG-SGC inhibition suppressed MI-induced cardiac sympathetic hyperexcitability. Moreover, the persistent inhibition of SG-SGCs improved ventricular arrhythmogenesis, remodeling and dysfunction, alleviated SG and ventricular sympathetic nerve sprouting 7d post-MI. In addition, the bulk RNA sequencing with SG and pharmacological purinergic receptor P2Y1 (P2Y1R) blockage indicated that P2Y1R/insulin like growth factor binding protein 2 (IGFBP2) signaling might mediate the effects of SG-SGC activation on cardiac sympathetic hyperexcitability post-MI. Conclusions: SGC inhibition in SG rectifies cardiac sympathetic hyperactivity, stabilizes ventricular electrophysiological properties and alleviates cardiac structural and neural remodeling post-MI, and resultantly preventing VAs and cardiac dysfunction. Neuromodulation targeting SG-SGCs exhibits a safe and fruitful strategy for the treatment of MI.

Abstract Background Only a few studies have investigated the association of environmental factors with DNA methylation in schizophrenia (SZ). Our study sought to investigate differentially methylated positions (DMPs) and differentially methylated regions (DMRs) between patients with psychosis and healthy controls (HCs) and to explore associations of aberrant methylation levels with the Korea-Polyenvironmental Risk Score-I (K-PERS-I), a comprehensive tool measuring polyenvironmental risk factors for psychosis. Study Design Blood-based methylome-wide association study (MWAS) was conducted in patients with psychosis (n=414) and HCs (n=225). For MWAS, a new cutting-edge technique, Methyl-Seq was employed. Using the K-PERS-I, polyenvironmental risk factors were assessed. Psychosis-associated DMPs and DMRs were identified via beta-binomial regression, and their associations with K-PERS-I scores were examined. Study Results We identified 1,138 DMPs and 1,611 DMRs associated with psychosis. In the correlation analysis, 12 DMPs-annotated genes and 11 DMRs-annotated genes were associated with childhood adversity. These genes were mainly implicated in neuronal development, neurotransmitter release, synaptic plasticity, immune response and oxidative stress. For obstetric complications, most of top 5 DMPs-annotated genes were implicated in placenta function, embryonic development or gestation. For recent adult life events, top 5 DMPs- and DMRs-annotated genes were related to neurotransmitter production/release, oxidative stress and stress regulation. Conclusions We identified new psychosis-associated DMPs and DMRs. More importantly, we demonstrated how environmental factors can be biologically embedded in DNA methylation of certain genes in patients with psychosis. Ultimately, establishing causal pathways between these risk factors and DNA methylation could lead to the discovery of novel therapeutic targets.

General stress-response of vertebrates to fluctuations of environmental conditions are conservative, and includes rapid release of neurotransmitters into blood. In amphibians, physiological effects of catecholamines (CA) on red blood cell (RBC) functions have been studied fragmentally despite the presence of adrenoreceptors on RBC membranes. In the present work the influence of epinephrine on RBC stability to hypoosmotic stress as well as intracellular reactive oxygen species (ROS) production levels and mitochondrial membrane potential have been studied on RBCs of marsh frogs Pelophylax ridibundus (in vitro). Additionally, the involvement of cAMP/Adenylate cyclase/protein kinase A (cAMP/AC/PKA) pathway in regulation of these processes have been evaluated. We showed that increase of RBC stability to hypoosmotic shock is mediated by activation of β-adrenoreceptors and independent from cAMP/PKA pathway. Lysis of RBCs treated with epinephrine occurred at lower osmolarities compared to non-stimulated cells and changes in RBC membrane properties were rapid (after 5 min incubation) and stable (following 60 min incubation). Addition of epinephrine to RBC suspensions or activation of cAMP/AC/PKA pathway (forskolin and cBIMPS) was associated with a reduction of ROS concentration in cytoplasm and enhanced mitochondrial membrane potential. The results of the present work provide novel insights into the cellular mechanisms of adrenergic RBC stimulation and pathways involved into signal transduction within the context of environmental stress. Stimulating effects of epinephrine on RBC membrane stability and mitochondrial activity is probably important for adaptation of frogs to unfavorable habitat conditions, seasonal activity and other stress factors.

The synaptic vesicle cycle is a critical process that ensures efficient neurotransmission across synaptic junctions, facilitating proper communication within the neuronal circuits. This cycle comprises several tightly regulated steps, including vesicle biogenesis, fusion with the presynaptic membrane, recycling, and degradation, all of which are essential for maintaining synaptic function. Specialized proteins orchestrate the molecular machinery responsible for coordinating vesicle trafficking throughout each stage of the cycle. In recent years, research has highlighted the emerging role of epigenetic regulation in modulating the synaptic vesicle cycle. Epigenetic modifications, such as DNA methylation, histone acetylation, and microRNA expression, regulate vesicle dynamics by modulating key stages of the vesicle trafficking cycle, that in turn affects neurotransmitter release and synaptic plasticity. These regulatory mechanisms ensure synaptic health and proper neuronal communication, while their disruption has been linked to synaptopathies, including autism, schizophrenia, Parkinson's, and Alzheimer's diseases. By examining both molecular and epigenetic factors, this review provides valuable insights into how gene expression and protein function are intricately involved in the regulation of the synaptic vesicle cycle. It highlights the importance of key events in regulating the synaptic vesicle cycle, their potential epigenetic drivers, and their relevance to addressing synaptic dysfunctions in various neurological disorders.

Sphingomyelin regulates astrocyte activity by regulating NF-κB signaling via HDAC1/3 expression.

Precise fabrication of spatially engineered brochosomes for in-situ investigation of cellular ROS secretion.

The force-sensing GPCR LPHN2 is indispensable for normal auditory function.

Development of a microelectrode array system for simultaneous measurement of field potential and glutamate release in brain slices.

The role of glia cell in the neural mechanism of memory formation, storage, and motor control: A review.

Pudendal neuropathy is a cause of pelvic pain, specifically pudendal neuralgia. The pudendal nerve is related to sensory, motor, and autonomic functions. We present the case of a 41-year-old man who suffered from chronic pelvic pain. In detail, the patient described stinging burning pain in the glans penis, proctalgia, lower urinary tract symptoms, sensation of "muscle tension" and squeezing pain. He was diagnosed with prostatitis and, following, pudendal neuralgia. Our patient was treated with antibiotics and analgesics, without improvement of symptoms. He was then submitted to decompression surgery of the pudendal nerve, with partial improvement. The patient started a rehabilitation program and was treated with OnabotulinumtoxinA (BoNT-A) injections into the piriformis muscle with benefit. BoNT-A positive effects on pain relief may corroborate piriformis muscle compression of the pudendal nerve. BoNT-A may also reduce the release of neurotransmitters from the pain pathways. Early identification of pudendal neuralgia could have prevented the progression to chronic pain. There is still not an established role for BoNT-A in post-operative pudendal nerve decompression patients. Our case corroborates that more studies should be performed to explore BoNT-A administration in these patients.

From synaptic dynamics to cognitive decline: Molecular insights into neuroplasticity.

α7 nicotinic acetylcholine receptor and depression: Mechanistic insights and therapeutic prospects.

In addition to their role in canonical autophagy, autophagy proteins (ATG) contribute to various cellular processes, including phagocytosis, membrane remodeling, and vesicle secretion. Several viruses also exploit components of the autophagy pathway for their own replication. Here, we explore the role of ATG proteins in HIV-1 assembly. Postulating that host proteins crucial for virion assembly are present at the assembly site and can be incorporated within virions, we analyze the proteome of HIV-1 preparations using mass spectrometry. We identify an enrichment of macroautophagy-related terms, notably 3 of the 6 ATG8 (LC3/GABARAP) proteins. Functional studies reveal that GABARAP proteins are critical for the production of infectious virions. Knockout of GABARAP proteins reduces the packaging of viral genomic RNA (gRNA) into particles, impairing virion infectivity. GABARAPL1 associates with gRNA and interacts with Gag in an RNA-dependent manner. Additionally, GABARAP knockout increases cellular Gag:gRNA complexes and decreases gRNA association with membranes, suggesting that GABARAP proteins regulate gRNA fate during HIV-1 assembly by facilitating its packaging. This study uncovers a novel role for GABARAP proteins in HIV-1 genome packaging.

Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins drive synaptic transmission in a temporally and spatially precise manner. Recent studies have identified several disease-causing SNARE variants that give rise to developmental and epileptic encephalopathies, defined as SNAREopathies. Here, we investigated nine synaptobrevin-2 (VAMP2) disease-causing variants and uncovered their specific SNARE complex affinity, stability, and conformational deficits that drive dysregulated neurotransmission. The neurotransmission deficits we observed parallel the symptomatic heterogeneity of the patients, with some variants displaying a disproportionate augmentation of spontaneous neurotransmitter release. When we examined the spatial organization of this excessive spontaneous release at nanoscale, we found that SNARE complexes composed of these variants formed exclusively outside of RIM scaffolding, revealing a preserved exclusion zone sparing evoked release from pathophysiology. Taken together with the phenotypes of previously reported disease-causing SNARE variants, these findings reveal shared patterns of aberrant neurotransmission across different SNAREs, highlighting the necessity for a functional classification of SNAREopathies to develop therapeutic interventions. The use of clinically relevant genetic manipulations to challenge the synapse provides mechanistic insight into rare diseases while simultaneously revealing fundamental aspects of synaptic physiology.

BLTP1 (Bridge-Like Lipid Transfer Protein Family Member 1), previously known as Tweek, Kiaa1109, FSA, or 4932438A13Rik, is a nonvesicular lipid transport protein linked to Alkuraya-Kučinskas syndrome (AKS), an autosomal recessive disorder with severe brain malformations and arthrogryposis in humans. Although BLTP1 is known to be involved in the transfer of phospholipids between organellar membranes at membrane contact sites, its specific role during mammalian development remains poorly defined. Here we characterized the development of the neuromuscular junction (NMJ) in Bltp1 knock-out (Bltp1-/- ) mice of either sex. These mutant mice die perinatally, exhibiting reduced growth of intramuscular motor nerves and a reduction in the size of the NMJ, compared with littermate controls. Electrophysiological analysis of the diaphragm muscle in Bltp1 -/- embryos reveals defects in synaptic transmission at the NMJ. Notably, the frequency of spontaneous neurotransmitter release is markedly increased, whereas evoked neurotransmitter release and quantal content are reduced. In addition, neuromuscular synapses in Bltp1 -/- mice fail to respond to a repetitive stimulation. Remarkably, the impairment of intramuscular nerve growth in Bltp1-/- embryos is restored by supplementing pregnant dams with lecithin, a mixture of unsaturated phospholipids naturally present in foods, although lecithin supplement does not improve the overall survival of these mutant mice. Together, these results demonstrate that BLTP1 plays important roles during development for proper intramuscular nerve growth and neuromuscular synaptic function and suggest that AKS patients may benefit from phospholipid supplementation such as lecithin.

Background: Neonatal hypoxic ischemia (HI) injury results in neuronal cell death, which remains clinically challenging to mitigate. Omega-3 polyunsaturated fatty acids (PUFAs) are known for their antioxidative and anti-inflammatory effects. Folic acid (FA) correlates with apoptosis in neural stem cells and neurons. Objectives: This study aimed to evaluate whether combined PUFA and FA supplementation mitigates neonatal HI brain injury by reducing apoptosis, inflammation, neurotransmitter imbalance, and electrophysiological dysfunction, thereby offering enhanced neuroprotection and functional recovery. Methods: Brain tissue damage, orthodromic population spike (OPS), and hypoxic injury potential (HIP) were measured. Amino acid neurotransmitter concentration in the hippocampus sections was measured. Markers of inflammation and apoptosis were assayed from HI-induced rat brains and lipopolysaccharide (LPS)-induced microglia BV-2 cells. Results: The HI caused severe damage to brain tissues that were potentially prevented by PUFA-FA by reducing the infarct size by 88%. The PUFA-FA treatment decreased the latency time (51 and 43 s) and increased swimming velocity (152 and 170 mm/s) on training days 3 and 5. The PUFA-FA showed an improved OPS decay time of 327 s, OPS recovery rate (62 s), and recovery amplitude (58 s). Whereas it caused an average 57% HIP incidence with a notably delayed onset (564 s) and duration (182 s). The PUFA-FA treatment also decreased the HI-induced release of amino acid neurotransmitters (Asp, Glu, and Gly) and GABA. The PUFA-FA suppressed the levels of proinflammatory cytokines and chemokines (iNOS, COX-2, TNF-α, IL-1β, and IL-6) and might mediate the inhibition of the NF-κB signaling pathway. The PUFA-FA reduced apoptosis as evidenced by lowered expression of AIF, caspase-3, and PARP genes. Conclusions: The PUFA and FA reduced HI-induced brain infarct size, with the combination showing greater protection compared to individual effects. Both improved cognitive performances, decreasing latency times and enhancing swimming velocity. The PUFA-FA supplementation synergistically restored memory, learning, and motor functions, highlighting strong neuroprotective effects against HI-induced neuronal degeneration and cognitive impairments.