Muscularis macrophages controlled by NLRP3 maintain the homeostasis of excitatory neurons.

Peristaltic movements in gut are essential to propel ingested materials through the gastrointestinal tract. Intestinal resident macrophages play an important role in this physiological function through protecting enteric neurons. However, it is incompletely clear how individuals maintain the homeostasis of gut motility. Here we found that NLRP3 is a critical factor in controlling loss of muscularis resident macrophages (MMs), and demonstrate that MMs are involved in the homeostasis of excitatory neurons such as choline acetyltransferase (ChAT)+ and vesicular glutamate transporter 2 (VGLUT2)+ but not inhibitory neuronal nitric oxide synthase (nNOS)+ neurons. NLRP3 knockout (KO) mice had enhanced gut motility and increased neurons, especially excitatory ChAT+ and VGLUT2+ neurons. Single cell analyses showed that there had increased resident macrophages, especially MMs in NLRP3 KO mice. The MM proportion in the resident macrophages was markedly higher than those in wild-type (WT) or caspase 1/11 KO mice. Deletion of the MMs and transplantation of the NLRP3 KO bone marrow cells showed that survival of the gut excitatory ChAT+ and VGLUT2+ neurons was dependent on the MMs. Gut microbiota metabolites ß-hydroxybutyrate (BHB) could promote gut motility through protecting MMs from pyroptosis. Thus, our data suggest that MMs regulated by NLRP3 maintain the homeostasis of excitatory neurons.

Implication of thermal signaling in neuronal differentiation revealed by manipulation and measurement of intracellular temperature.

Neuronal differentiation-the development of neurons from neural stem cells-involves neurite outgrowth and is a key process during the development and regeneration of neural functions. In addition to various chemical signaling mechanisms, it has been suggested that thermal stimuli induce neuronal differentiation. However, the function of physiological subcellular thermogenesis during neuronal differentiation remains unknown. Here we create methods to manipulate and observe local intracellular temperature, and investigate the effects of noninvasive temperature changes on neuronal differentiation using neuron-like PC12 cells. Using quantitative heating with an infrared laser, we find an increase in local temperature (especially in the nucleus) facilitates neurite outgrowth. Intracellular thermometry reveals that neuronal differentiation is accompanied by intracellular thermogenesis associated with transcription and translation. Suppression of intracellular temperature increase during neuronal differentiation inhibits neurite outgrowth. Furthermore, spontaneous intracellular temperature elevation is involved in neurite outgrowth of primary mouse cortical neurons. These results offer a model for understanding neuronal differentiation induced by intracellular thermal signaling.

Valproic Acid Treatment after Traumatic Brain Injury in Mice Alleviates Neuronal Death and Inflammation in Association with Increased Plasma Lysophosphatidylcholines.

The histone deacetylase inhibitor (HDACi) valproic acid (VPA) has neuroprotective and anti-inflammatory effects in experimental traumatic brain injury (TBI), which have been partially attributed to the epigenetic disinhibition of the transcription repressor RE1-Silencing Transcription Factor/Neuron-Restrictive Silencer Factor (REST/NRSF). Additionally, VPA changes post-traumatic brain injury (TBI) brain metabolism to create a neuroprotective environment. To address the interconnection of neuroprotection, metabolism, inflammation and REST/NRSF after TBI, we subjected C57BL/6N mice to experimental TBI and intraperitoneal VPA administration or vehicle solution at 15 min, 1, 2, and 3 days post-injury (dpi). At 7 dpi, TBI-induced an up-regulation of REST/NRSF gene expression and HDACi function of VPA on histone H3 acetylation were confirmed. Neurological deficits, brain lesion size, blood-brain barrier permeability, or astrogliosis were not affected, and REST/NRSF target genes were only marginally influenced by VPA. However, VPA attenuated structural damage in the hippocampus, microgliosis and expression of the pro-inflammatory marker genes. Analyses of plasma lipidomic and polar metabolomic patterns revealed that VPA treatment increased lysophosphatidylcholines (LPCs), which were inversely associated with interleukin 1 beta (Il1b) and tumor necrosis factor (Tnf) gene expression in the brain. The results show that VPA has mild neuroprotective and anti-inflammatory effects likely originating from favorable systemic metabolic changes resulting in increased plasma LPCs that are known to be actively taken up by the brain and function as carriers for neuroprotective polyunsaturated fatty acids.

Antiviral, anti-inflammatory and antioxidant effects of curcumin and curcuminoids in SH-SY5Y cells infected by SARS-CoV-2.

COVID-19, caused by SARS-CoV-2, affects neuronal cells, causing several symptoms such as memory loss, anosmia and brain inflammation. Curcuminoids (Me08 e Me23) and curcumin (CUR) are derived from Curcuma Longa extract (EXT). Many therapeutic actions have been linked to these compounds, including antiviral action. Given the severe implications of COVID-19, especially within the central nervous system, our study aims to shed light on the therapeutic potential of curcuminoids against SARS-CoV-2 infection, particularly in neuronal cells. Here, we investigated the effects of CUR, EXT, Me08 and Me23 in human neuroblastoma SH-SY5Y. We observed that Me23 significantly decreased the expression of plasma membrane-associated transmembrane protease serine 2 (TMPRSS2) and TMPRSS11D, consequently mitigating the elevated ROS levels induced by SARS-CoV-2. Furthermore, Me23 exhibited antioxidative properties by increasing NRF2 gene expression and restoring NQO1 activity following SARS-CoV-2 infection. Both Me08 and Me23 effectively reduced SARS-CoV-2 replication in SH-SY5Y cells overexpressing ACE2 (SH-ACE2). Additionally, all of these compounds demonstrated the ability to decrease proinflammatory cytokines such as IL-6, TNF-α, and IL-17, while Me08 specifically reduced INF-γ levels. Our findings suggest that curcuminoid Me23 could serve as a potential agent for mitigating the impact of COVID-19, particularly within the context of central nervous system involvement.

Exploring the neuroprotective role of artesunate in mouse models of anti-NMDAR encephalitis: insights from molecular mechanisms and transmission electron microscopy.

BACKGROUND: The pathway involving PTEN-induced putative kinase 1 (PINK1) and PARKIN plays a crucial role in mitophagy, a process activated by artesunate (ART). We propose that patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis exhibit insufficient mitophagy, and ART enhances mitophagy via the PINK1/PARKIN pathway, thereby providing neuroprotection. METHODS: Adult female mice aged 8-10 weeks were selected to create a passive transfer model of anti-NMDAR encephalitis. We conducted behavioral tests on these mice within a set timeframe. Techniques such as immunohistochemistry, immunofluorescence, and western blotting were employed to assess markers including PINK1, PARKIN, LC3B, p62, caspase3, and cleaved caspase3. The TUNEL assay was utilized to detect neuronal apoptosis, while transmission electron microscopy (TEM) was used to examine mitochondrial autophagosomes. Primary hippocampal neurons were cultured, treated, and then analyzed through immunofluorescence for mtDNA, mtROS, TMRM. RESULTS: In comparison to the control group, mitophagy levels in the experimental group were not significantly altered, yet there was a notable increase in apoptotic neurons. Furthermore, markers indicative of mitochondrial leakage and damage were found to be elevated in the experimental group compared to the control group, but these markers showed improvement following ART treatment. ART was effective in activating the PINK1/PARKIN pathway, enhancing mitophagy, and diminishing neuronal apoptosis. Behavioral assessments revealed that ART ameliorated symptoms in mice with anti-NMDAR encephalitis in the passive transfer model (PTM). The knockdown of PINK1 led to a reduction in mitophagy levels, and subsequent ART intervention did not alleviate symptoms in the anti-NMDAR encephalitis PTM mice, indicating that ART's therapeutic efficacy is mediated through the activation of the PINK1/PARKIN pathway. CONCLUSIONS: At the onset of anti-NMDAR encephalitis, mitochondrial damage is observed; however, this damage is mitigated by the activation of mitophagy via the PINK1/PARKIN pathway. This regulatory feedback mechanism facilitates the removal of damaged mitochondria, prevents neuronal apoptosis, and consequently safeguards neural tissue. ART activates the PINK1/PARKIN pathway to enhance mitophagy, thereby exerting neuroprotective effects and may achieve therapeutic goals in treating anti-NMDAR encephalitis.

Interleukin-9 protects from microglia- and TNF-mediated synaptotoxicity in experimental multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a progressive neurodegenerative disease of the central nervous system characterized by inflammation-driven synaptic abnormalities. Interleukin-9 (IL-9) is emerging as a pleiotropic cytokine involved in MS pathophysiology. METHODS: Through biochemical, immunohistochemical, and electrophysiological experiments, we investigated the effects of both peripheral and central administration of IL-9 on C57/BL6 female mice with experimental autoimmune encephalomyelitis (EAE), a model of MS. RESULTS: We demonstrated that both systemic and local administration of IL-9 significantly improved clinical disability, reduced neuroinflammation, and mitigated synaptic damage in EAE. The results unveil an unrecognized central effect of IL-9 against microglia- and TNF-mediated neuronal excitotoxicity. Two main mechanisms emerged: first, IL-9 modulated microglial inflammatory activity by enhancing the expression of the triggering receptor expressed on myeloid cells-2 (TREM2) and reducing TNF release. Second, IL-9 suppressed neuronal TNF signaling, thereby blocking its synaptotoxic effects. CONCLUSIONS: The data presented in this work highlight IL-9 as a critical neuroprotective molecule capable of interfering with inflammatory synaptopathy in EAE. These findings open new avenues for treatments targeting the neurodegenerative damage associated with MS, as well as other inflammatory and neurodegenerative disorders of the central nervous system.

Dynamin1 long- and short-tail isoforms exploit distinct recruitment and spatial patterns to form endocytic nanoclusters.

Endocytosis requires a coordinated framework of molecular interactions that ultimately lead to the fission of nascent endocytic structures. How cytosolic proteins such as dynamin concentrate at discrete sites that are sparsely distributed across the plasma membrane remains poorly understood. Two dynamin-1 major splice variants differ by the length of their C-terminal proline-rich region (short-tail and long-tail). Using sptPALM in PC12 cells, neurons and MEF cells, we demonstrate that short-tail dynamin-1 isoforms ab and bb display an activity-dependent recruitment to the membrane, promptly followed by their concentration into nanoclusters. These nanoclusters are sensitive to both Calcineurin and dynamin GTPase inhibitors, and are larger, denser, and more numerous than that of long-tail isoform aa. Spatiotemporal modelling confirms that dynamin-1 isoforms perform distinct search patterns and undergo dimensional reduction to generate endocytic nanoclusters, with short-tail isoforms more robustly exploiting lateral trapping in the generation of nanoclusters compared to the long-tail isoform.

DNA origami scaffold promoting nerve guidance and regeneration.

Self-assembly of biological elements into biomimetic cargo carriers for targeting and delivery is a promising approach. However, it still holds practical challenges. We developed a functionalization approach of DNA origami (DO) nanostructures with neuronal growth factor (NGF) for manipulating neuronal systems. NGF bioactivity and its interactions with the neuronal system were demonstrated in vitro and in vivo models. The DO elements fabricated by molecular self-assembly have manipulated the surrounding environment through static spatially and temporally controlled presentation of ligands to the cell surface receptors. Our data showed effective bioactivity in differentiating PC12 cells in vitro. Furthermore, the DNA origami NGF (DON) affected the growth directionality and spatial capabilities of dorsal root ganglion neurons in culture by introducing a chemotaxis effect along a gradient of functionalized DO structures. Finally, we showed that these elements provide enhanced axonal regeneration in a rat sciatic nerve injury model in vivo. This study is a proof of principle for the functionality of DO in neuronal manipulation and regeneration. The approach proposed here, of an engineered platform formed out of programmable nanoscale elements constructed of DO, could be extended beyond the nervous system and revolutionize the fields of regenerative medicine, tissue engineering, and cell biology.

Neurons upregulate PD-L1 via IFN/STAT1/IRF1 to alleviate damage by CD8+ T cells in cerebral malaria.

BACKGROUND: Cerebral malaria (CM) is the most lethal complication of malaria, and survivors usually endure neurological sequelae. Notably, the cytotoxic effect of infiltrating Plasmodium-activated CD8+ T cells on cerebral microvasculature endothelial cells is a prominent feature of the experimental CM (ECM) model with blood-brain barrier disruption. However, the damage effect of CD8+ T cells infiltrating the brain parenchyma on neurons remains unclear. Based on the immunosuppressive effect of the PD-1/PD-L1 pathway on T cells, our previous study demonstrated that the systemic upregulation of PD-L1 to inhibit CD8+ T cell function could effectively alleviate the symptoms of ECM mice. However, it has not been reported whether neurons can suppress the pathogenic effect of CD8+ T cells through the PD-1/PD-L1 negative immunomodulatory pathway. As the important inflammatory factor of CM, interferons can induce the expression of PD-L1 via different molecular mechanisms according to the neuro-immune microenvironment. Therefore, this study aimed to investigate the direct interaction between CD8+ T cells and neurons, as well as the mechanism of neurons to alleviate the pathogenic effect of CD8+ T cells through up-regulating PD-L1 induced by IFNs. METHODS: Using the ECM model of C57BL/6J mice infected with Plasmodium berghei ANKA (PbA), morphological observations were conducted in vivo by electron microscope and IF staining. The interaction between the ECM CD8+ T cells (immune magnetic bead sorting from spleen of ECM mice) and primary cultured cortical neurons in vitro was observed by IF staining and time-lapse photography. RNA-seq was performed to analyze the signaling pathway of PD-L1 upregulation in neurons induced by IFNß or IFNγ, and verified through q-PCR, WB, IF staining, and flow cytometry both in vitro and in vivo using IFNAR or IFNGR gene knockout mice. The protective effect of adenovirus-mediated PD-L1 IgGFc fusion protein expression was verified in ECM mice with brain stereotaxic injection in vivo and in primary cultured neurons via viral infection in vitro. RESULTS: In vivo, ECM mice showed infiltration of activated CD8+ T cells and neuronal injury in the brain parenchyma. In vitro, ECM CD8+ T cells were in direct contact with neurons and induced axonal damage, as an active behavior. The PD-L1 protein level was elevated in neurons of ECM mice and in primary cultured neurons induced by IFNß, IFNγ, or ECM CD8+ T cells in vitro. Furthermore, the IFNß or IFNγ induced neuronal expression of PD-L1 was mediated by increasing STAT1/IRF1 pathway via IFN receptors. The increase of PD-L1 expression in neurons during PbA infection was weakened after deleting the IFNAR or IFNGR. Increased PD-L1 expression by adenovirus partially protected neurons from CD8+ T cell-mediated damage both in vitro and in vivo. CONCLUSION: Our study demonstrates that both type I and type II IFNs can induce neurons to upregulate PD-L1 via the STAT1/IRF1 pathway mediated by IFN receptors to protect against activated CD8+ T cell-mediated damage, providing a targeted pathway to alleviate neuroinflammation during ECM.

Spiking Neural Membrane Systems with Adaptive Synaptic Time Delay.

Spiking neural membrane systems (or spiking neural P systems, SNP systems) are a new type of computation model which have attracted the attention of plentiful scholars for parallelism, time encoding, interpretability and extensibility. The original SNP systems only consider the time delay caused by the execution of rules within neurons, but not caused by the transmission of spikes via synapses between neurons and its adaptive adjustment. In view of the importance of time delay for SNP systems, which are a time encoding computation model, this study proposes SNP systems with adaptive synaptic time delay (ADSNP systems) based on the dynamic regulation mechanism of synaptic transmission delay in neural systems. In ADSNP systems, besides neurons, astrocytes that can generate adenosine triphosphate (ATP) are introduced. After receiving spikes, astrocytes convert spikes into ATP and send ATP to the synapses controlled by them to change the synaptic time delays. The Turing universality of ADSNP systems in number generating and accepting modes is proved. In addition, a small universal ADSNP system using 93 neurons and astrocytes is given. The superiority of the ADSNP system is demonstrated by comparison with the six variants. Finally, an ADSNP system is constructed for credit card fraud detection, which verifies the feasibility of the ADSNP system for solving real-world problems. By considering the adaptive synaptic delay, ADSNP systems better restore the process of information transmission in biological neural networks, and enhance the adaptability of SNP systems, making the control of time more accurate.

Alternative splicing of a chromatin modifier alters the transcriptional regulatory programs of stem cell maintenance and neuronal differentiation.

Development of embryonic stem cells (ESCs) into neurons requires intricate regulation of transcription, splicing, and translation, but how these processes interconnect is not understood. We found that polypyrimidine tract binding protein 1 (PTBP1) controls splicing of DPF2, a subunit of BRG1/BRM-associated factor (BAF) chromatin remodeling complexes. Dpf2 exon 7 splicing is inhibited by PTBP1 to produce the DPF2-S isoform early in development. During neuronal differentiation, loss of PTBP1 allows exon 7 inclusion and DPF2-L expression. Different cellular phenotypes and gene expression programs were induced by these alternative DPF2 isoforms. We identified chromatin binding sites enriched for each DPF2 isoform, as well as sites bound by both. In ESC, DPF2-S preferential sites were bound by pluripotency factors. In neuronal progenitors, DPF2-S sites were bound by nuclear factor I (NFI), while DPF2-L sites were bound by CCCTC-binding factor (CTCF). DPF2-S sites exhibited enhancer modifications, while DPF2-L sites showed promoter modifications. Thus, alternative splicing redirects BAF complex targeting to impact chromatin organization during neuronal development.

BAP1 is required prenatally for differentiation and maintenance of postnatal murine enteric nervous system.

Epigenetic regulatory mechanisms are underappreciated, yet are critical for enteric nervous system (ENS) development and maintenance. We discovered that fetal loss of the epigenetic regulator Bap1 in the ENS lineage caused severe postnatal bowel dysfunction and early death in Tyrosinase-Cre Bap1fl/fl mice. Bap1-depleted ENS appeared normal in neonates; however, by P15, Bap1-deficient enteric neurons were largely absent from the small and large intestine of Tyrosinase-Cre Bap1fl/fl mice. Bowel motility became markedly abnormal with disproportionate loss of cholinergic neurons. Single-cell RNA sequencing at P5 showed that fetal Bap1 loss in Tyrosinase-Cre Bap1fl/fl mice markedly altered the composition and relative proportions of enteric neuron subtypes. In contrast, postnatal deletion of Bap1 did not cause enteric neuron loss or impaired bowel motility. These findings suggest that BAP1 is critical for postnatal enteric neuron differentiation and for early enteric neuron survival, a finding that may be relevant to the recently described human BAP1-associated neurodevelopmental disorder.

Modeling the effect of magnetoelectric nanoparticles on neuronal electrical activity: An analog circuit approach.

This paper introduces a physical neuron model that incorporates magnetoelectric nanoparticles (MENPs) as an essential electrical circuit component to wirelessly control local neural activity. Availability of such a model is important as MENPs, due to their magnetoelectric effect, can wirelessly and noninvasively modulate neural activity, which, in turn, has implications for both finding cures for neurological diseases and creating a wireless noninvasive high-resolution brain-machine interface. When placed on a neuronal membrane, MENPs act as magnetic-field-controlled finite-size electric dipoles that generate local electric fields across the membrane in response to magnetic fields, thus allowing to controllably activate local ion channels and locally initiate an action potential. Herein, the neuronal electrical characteristic description is based on ion channel activation and inhibition mechanisms. A MENP-based memristive Hodgkin-Huxley circuit model is extracted by combining the Hodgkin-Huxley model and an equivalent circuit model for a single MENP. In this model, each MENP becomes an integral part of the neuron, thus enabling wireless local control of the neuron's electric circuit itself. Furthermore, the model is expanded to include multiple MENPs to describe collective effects in neural systems.

The HSV-1 pUL37 protein promotes cell invasion by regulating the kinesin-1 motor.

Neurotropic alphaherpesviruses, including herpes simplex virus type 1 (HSV-1), recruit microtubule motor proteins to invade cells. The incoming viral particle traffics to nuclei in a two-step process. First, the particle uses the dynein-dynactin motor to sustain transport to the centrosome. In neurons, this step is responsible for long-distance retrograde axonal transport and is an important component of the neuroinvasive property shared by these viruses. Second, a kinesin-dependent mechanism redirects the particle from the centrosome to the nucleus. We have reported that the kinesin motor used during the second step of invasion is assimilated into nascent virions during the previous round of infection. Here, we report that the HSV-1 pUL37 tegument protein suppresses the assimilated kinesin-1 motor during retrograde axonal transport. Region 2 (R2) of pUL37 was required for suppression and functioned independently of the autoinhibitory mechanism native to kinesin-1. Furthermore, the motor domain and proximal coiled coil of kinesin-1 were sufficient for HSV-1 assimilation, pUL37 suppression, and nuclear trafficking. pUL37 localized to the centrosome, the site of assimilated kinesin-1 activation during infection, when expressed in cells in the absence of other viral proteins; however, pUL37 did not suppress kinesin-1 in this context. These results indicate that the pUL37 tegument protein spatially and temporally regulates kinesin-1 via the amino-terminal motor region in the context of the incoming viral particle.

Correlation between desynchrony of hippocampal neural activity and hyperlocomotion in the model mice of schizophrenia and therapeutic effects of aripiprazole.

AIMS: The hippocampus has been reported to be morphologically and neurochemically altered in schizophrenia (SZ). Hyperlocomotion is a characteristic SZ-associated behavioral phenotype, which is associated with dysregulated dopamine system function induced by hippocampal hyperactivity. However, the neural mechanism of hippocampus underlying hyperlocomotion remains largely unclear. METHODS: Mouse pups were injected with N-methyl-D-aspartate receptor antagonist (MK-801) or vehicle twice daily on postnatal days (PND) 7-11. In the adulthood phase, one cohort of mice underwent electrode implantation in field CA1 of the hippocampus for the recording local field potentials and spike activity. A separate cohort of mice underwent surgery to allow for calcium imaging of the hippocampus while monitoring the locomotion. Lastly, the effects of atypical antipsychotic (aripiprazole, ARI) were evaluated on hippocampal neural activity. RESULTS: We found that the hippocampal theta oscillations were enhanced in MK-801-treated mice, but the correlation coefficient between the hippocampal spiking activity and theta oscillation was reduced. Consistently, although the rate and amplitude of calcium transients of hippocampal neurons were increased, their synchrony and correlation to locomotion speed were disrupted. ARI ameliorated perturbations produced by the postnatal MK-801 treatment. CONCLUSIONS: These results suggest that the disruption of neural coordination may underly the neuropathological mechanism for hyperlocomotion of SZ.

Melatonin Enhances Neural Differentiation of Adipose-Derived Mesenchymal Stem Cells.

Adipose-derived mesenchymal stem cells (ASCs) are adult multipotent stem cells, able to differentiate toward neural elements other than cells of mesodermal lineage. The aim of this research was to test ASC neural differentiation using melatonin combined with conditioned media (CM) from glial cells. Isolated from the lipoaspirate of healthy donors, ASCs were expanded in a basal growth medium before undergoing neural differentiation procedures. For this purpose, CM obtained from olfactory ensheathing cells and from Schwann cells were used. In some samples, 1 µM of melatonin was added. After 1 and 7 days of culture, cells were studied using immunocytochemistry and flow cytometry to evaluate neural marker expression (Nestin, MAP2, Synapsin I, GFAP) under different conditions. The results confirmed that a successful neural differentiation was achieved by glial CM, whereas the addition of melatonin alone did not induce appreciable changes. When melatonin was combined with CM, ASC neural differentiation was enhanced, as demonstrated by a further improvement of neuronal marker expression, whereas glial differentiation was attenuated. A dynamic modulation was also observed, testing the expression of melatonin receptors. In conclusion, our data suggest that melatonin's neurogenic differentiation ability can be usefully exploited to obtain neuronal-like differentiated ASCs for potential therapeutic strategies.

Glucosamine Enhancement of Learning and Memory Functions by Promoting Fibroblast Growth Factor 21 Production.

Fibroblast growth factor 21 (FGF21) plays a crucial role in metabolism and brain function. Glucosamine (GLN) has been recognized for its diverse beneficial effects. This study aimed to elucidate the modulation of FGF21 production by GLN and its impact on learning and memory functions. Using both in vivo and in vitro models, we investigated the effects of GLN on mice fed with a normal diet or high-fat diet and on mouse HT22 hippocampal cells, STHdhQ7/Q7 striatal cells, and rat primary cortical neurons challenged with GLN. Our results indicated that GLN promotes learning and memory functions in mice and upregulates FGF21 expression in the hippocampus, cortex, and striatum, as well as in HT22 cells, STHdhQ7/Q7 cells, and cortical neurons. In animals receiving GLN together with an FGF21 receptor FGFR1 inhibitor (PD173074), the GLN-enhanced learning and memory functions and induction of FGF21 production in the hippocampus were significantly attenuated. While exploring the underlying molecular mechanisms, the potential involvement of NF-κB, Akt, p38, JNK, PKA, and PPARα in HT22 and NF-κB, Akt, p38, and PPARα in STHdhQ7/Q7 were noted; GLN was able to mediate the activation of p65, Akt, p38, and CREB in HT22 and p65, Akt, and p38 in STHdhQ7/Q7 cells. Our accumulated findings suggest that GLN may increase learning and memory functions by inducing FGF21 production in the brain. This induction appears to be mediated, at least in part, through GLN's activation of the NF-κB, Akt, p38, and PKA/CREB pathways.

Nanoscale detection of carbon dots-induced changes in actin skeleton of neural cells.

Understanding the cytotoxicity of fluorescent carbon dots (CDs) is crucial for their applications, and various biochemical assays have been used to study the effects of CDs on cells. Knowledge on the effects of CDs from a biophysical perspective is integral to the recognition of their cytotoxicity, however the related information is very limited. Here, we report that atomic force microscopy (AFM) can be used as an effective tool for studying the effects of CDs on cells from the biophysical perspective. We achieve this by integrating AFM-based nanomechanics with AFM-based imaging. We demonstrate the performance of this method by measuring the influence of CDs on living human neuroblastoma (SH-SY5Y) cells at the single-cell level. We find that high-dose CDs can mechanically induce elevated normalized hysteresis (energy dissipation during the cell deformation) and structurally impair actin skeleton. The nanomechanical change highly correlates with the alteration of actin filaments, indicating that CDs-induced changes in SH-SY5Y cells are revealed in-depth from the AFM-based biophysical aspect. We validate the reliability of the biophysical observations using conventional biological methods including cell viability test, fluorescent microscopy, and western blot assay. Our work contributes new and significant information on the cytotoxicity of CDs from the biophysical perspective.

Neuronal innervation regulates the secretion of neurotrophic myokines and exosomes from skeletal muscle.

Myokines and exosomes, originating from skeletal muscle, are shown to play a significant role in maintaining brain homeostasis. While exercise has been reported to promote muscle secretion, little is known about the effects of neuronal innervation and activity on the yield and molecular composition of biologically active molecules from muscle. As neuromuscular diseases and disabilities associated with denervation impact muscle metabolism, we hypothesize that neuronal innervation and firing may play a pivotal role in regulating secretion activities of skeletal muscles. We examined this hypothesis using an engineered neuromuscular tissue model consisting of skeletal muscles innervated by motor neurons. The innervated muscles displayed elevated expression of mRNAs encoding neurotrophic myokines, such as interleukin-6, brain-derived neurotrophic factor, and FDNC5, as well as the mRNA of peroxisome-proliferator-activated receptor γ coactivator 1α, a key regulator of muscle metabolism. Upon glutamate stimulation, the innervated muscles secreted higher levels of irisin and exosomes containing more diverse neurotrophic microRNAs than neuron-free muscles. Consequently, biological factors secreted by innervated muscles enhanced branching, axonal transport, and, ultimately, spontaneous network activities of primary hippocampal neurons in vitro. Overall, these results reveal the importance of neuronal innervation in modulating muscle-derived factors that promote neuronal function and suggest that the engineered neuromuscular tissue model holds significant promise as a platform for producing neurotrophic molecules.