Neuronal Expression Research Articles

The Receptor for Advanced Glycation End-products in the Mouse Anterior Cingulate Cortex is Involved in Neuron‒Astrocyte Coupling in Chronic Inflammatory Pain and Anxiety Comorbidity.

Previous studies have shown that astrocyte activation in the anterior cingulate cortex (ACC), accompanied by upregulation of the astrocyte marker S100 calcium binding protein B (S100B), contributes to comorbid anxiety in chronic inflammatory pain (CIP), but the exact downstream mechanism is still being explored. The receptor for advanced glycation end-products (RAGE) plays an important role in chronic pain and psychosis by recognizing ligands, including S100B. Therefore, we speculate that RAGE may be involved in astrocyte regulation of the comorbidity between CIP and anxiety by recognizing S100B. Here, we investigated the potential role of RAGE and the correlation between RAGE and astrocyte regulation in the ACC using a mouse model of complete Freund's adjuvant (CFA)-induced inflammatory pain. We detected substantial upregulation of RAGE expression in ACC neurons when anxiety-like behaviors occurred in CFA-treated mice. The inhibition of RAGE expression decreased the hyperexcitability of ACC neurons and alleviated both hyperalgesia and anxiety in CFA-treated mice. Furthermore, we found that the ACC astrocytic S100B level increased over a similar time course. Intra-ACC application of S100B or downregulation of ACC astrocytic S100B via suppression of astrocyte activation significantly affected RAGE levels and the relative behaviors of CFA-treated mice. Taken together, these findings suggest that the upregulation of ACC neuronal RAGE results from the activation of astrocytic S100B and leads to the maintenance of pain perception and anxiety in the late phase after CFA injection, which may partly explain the mechanism by which ACC neuron‒astrocyte coupling promotes the maintenance of CIP and anxiety comorbidity.

Reduced white matter integrity and disrupted brain network in children with type 2 and 3 spinal muscular atrophy

BackgroundSpinal muscular atrophy (SMA) is caused by reduced expression of survival motor neuron (SMN) protein. Previous studies indicated SMA causes not only lower motor neuron degeneration but also extensive brain involvement. This study aimed to investigate the changes of brain white matter and structural network using diffusion tensor imaging (DTI) in children with type 2 and 3 SMA.MethodsForty-two type 2 and 3 pediatric SMA patients and 42 age- and gender-matched healthy controls (HC) were prospectively enrolled in this study. The tract-based spatial statistics (TBSS) was used to assess white matter integrity and the structural network properties were calculated based on DTI white matter fiber tracking and the graph theory approach. A partial correlation was performed to explore the relationship between white matter parameters and clinical characteristics.ResultsIn total, 42 patients (mean age, 10.86 ± 4.07 years; 23 men) were included. TBSS analysis revealed widespread white matter changes in SMA patients. The SMA patients showed changes in multiple small-world and network efficiency parameters. Compared to the HC group, SMA showed increased characteristic path length (Lp), normalized clustering coefficient (γ), small-world characteristic (σ), and decreased global efficiency (Eglob) (all p < 0.05). In the node properties, right supramarginal gyrus, right orbital part of superior frontal gyrus, right supplementary motor area, and left median cingulate and paracingulate gyri changed in SMA patients. A decreased axial diffusivity (AD) value was associated with lower Hammersmith Functional Motor Scale-Expanded scores (r = 0.45, p = 0.02), which means that the symptoms of SMA patients are more severe.ConclusionsThis study found white matter and DTI-based brain network abnormalities in SMA patients, suggesting SMN protein deficiency may affect white matter development.

Neuronal Dual-Specificity Phosphatase 26 Inhibition via Reactive-Oxygen-Species Responsive Mesoporous-Silica-Loaded Hydrogel for Spinal Cord Injury Repair.

Spinal cord injury (SCI) remains a formidable challenge in biomedical research, as the silencing of intrinsic regenerative signals in most spinal neurons results in an inability to reestablish neural circuits. In this study, we found that neurons with low axonal regeneration after SCI showed decreased extracellular signal-regulated kinase (ERK) phosphorylation levels. However, the expression of dual specificity phosphatase 26 (DUSP26)─which negatively regulates ERK phosphorylation─was reduced considerably in neurons undergoing spontaneous axonal regeneration. Therefore, we developed a system named F10@MS@UV-HG that integrated a DUSP26-specific inhibitor into reactive oxygen species-responsive nanoparticles and embedded them in photosensitive hydrogels. This system effectively downregulated DUSP26 expression in primary neurons and enhanced ERK phosphorylation, ultimately promoting axonal outgrowth. When transplanted into an SCI mouse model, the system achieved sustained drug release, specifically targeting the DUSP26/ERK/ELK1 pathway in the spinal neurons and facilitating short-term axonal regeneration. Additionally, long-term repair effects─including improved myelination and enhanced motor function─were evident in the SCI mice transplanted with F10@MS@UV-HG. The results suggested that activating ERK signaling by modulating DUSP26 expression in neurons after SCI could effectively promote axonal regeneration and functional recovery. Thus, the developed F10@MS@UV-HG system exhibits enormous potential as a therapeutic approach for patients with SCI.

Neonatal but not Juvenile Gene Therapy Reduces Seizures and Prolongs Lifespan in SCN1B-Dravet Syndrome Mice.

Dravet syndrome (DS) is a developmental and epileptic encephalopathy (DEE) that begins in the first year of life. While most cases of DS are caused by variants in SCN1A, variants in SCN1B, encoding voltage-gated sodium channel β1 subunits, are also linked to DS or to the more severe early infantile DEE. Both disorders fall under the OMIM term DEE52. Scn1b null mice model DEE52, with spontaneous generalized seizures and death in 100% of animals in the third postnatal week. Scn1b null cortical parvalbumin-positive interneurons and pyramidal neurons are hypoexcitable. The goal of this study was to develop a proof-of-principle gene replacement strategy for DEE52. We tested an adeno-associated viral vector encoding β1 subunit cDNA (AAV-Navβ1) in Scn1b null mice. We demonstrated that AAV-Navβ1 drives β1 protein expression in excitatory and inhibitory neurons in mouse brain. Bilateral intracerebroventricular administration of AAV-Navβ1 in Scn1b null mice at postnatal day (P) 2, but not at P10, reduced spontaneous seizure severity and duration, prolonged life span, prevented hyperthermia-induced seizures, and restored cortical neuron excitability. AAV-Navβ1 administration to WT mice resulted in β1 overexpression in brain but no obvious adverse effects. This work lays the foundation for future development of a gene therapeutic strategy for SCN1B-linked DEE patients. .

DOP068 Vedolizumab counteracts Parkinson’s disease-related brain pathology driven by gut-primed IBD T cells

Abstract Background The gut-brain axis has been increasingly recognized as a critical pathway linking Inflammatory Bowel Diseases (IBD) with neurodegenerative diseases. Chronic inflammation resulting from IBD can extend beyond the gut, and epidemiological data have also linked to the increased prevalence of neurodegenerative conditions like Parkinson’s disease (PD). However, the exact mechanisms underlying this interconnection are largely unclear. We therefore investigated how gut-primed T cells from IBD patients may drive neurodegenerative processes seen in PD. Methods Peripheral blood T cells from IBD patients were analyzed for co-expression of gut-homing integrin α4β7 and brain-homing integrin β1. Using gut-specific photoconversion in a Kaede T cell Transfer Colitis mouse model, we assessed the infiltration of gut-primed T cells into the brain tissue. To model and elucidate the interplay of T cells with the brain tissue ex vivo, we developed an innovative three-dimensional co-culture system involving human stem cell-derived Brain Organoids (hBrO) and peripheral blood T cells from IBD patients and controls. Vedolizumab, an anti-α4β7 integrin antibody, was used to assess its potential in blocking T cell accumulation and subsequent neurotoxicity in hBrO cultures. Results Gut-primed T cells from IBD patients co-expressed brain-homing integrins, suggesting that they are able to enter brain tissue. Clear evidence of gut-to-brain T cell trafficking was obtained in the Kaede T cell Transfer Colitis mouse model, confirming the capacity of gut-primed T cells to migrate across the blood-brain barrier under conditions of chronic intestinal inflammation. In the hBrO co-culture model, neurons expressed MAdCAM-1, and MAdCAM-1 expression in neurons was also found in single cell RNA sequencing of postmortem brain tissue. Consistently, α4β7+ IBD T cells accumulated specifically in the vicinity of neurons, leading to neuronal cell death and aSyn aggregation (a hallmark of PD) in hBrO. In line, Vedolizumab treatment reduced IBD T cell accumulation in hBrO and preserved neural cell integrity. Conclusion Our data, for the first time, show a T cell trafficking-driven axis of gut-to-brain communication with pathogenic potential for the central nervous system in the context of IBD. Moreover, our findings suggest that neurotoxic T cell-neuron interaction is mediated by MADCAM1 and α4β7 integrin. Thus, our study reveals a novel pathway, by which IBD T cells may contribute to neurodegeneration, linking chronic gut inflammation to brain tissue pathology and synucleinopathy. Blocking α4β7-mediated T cell-induced neurotoxicity and aSyn pathology presents a potential therapeutic approach for IBD patients at risk of neurodegenerative diseases such as PD.

Characterization of Chitinase 3-like protein 1 spatiotemporal distribution in human post-traumatic brain contusions and other neuropathological scenarios.

Chitinase 3-like protein 1 (CHI3L1) is emerging as a promising biomarker for assessing intracranial lesion burden and predicting prognosis in traumatic brain injury (TBI) patients. Following experimental TBI, Chi3l1 transcripts were detected in reactive astrocytes located within the pericontusional cortex. However, the cellular sources of CHI3L1 in response to hemorrhagic contusions in human brain remain unidentified. Hence, we examined a comprehensive collection of histologically defined acute and subacute human cerebral contusions with various surgical intervals using immunohistochemistry, validated through double immunofluorescence for markers such as GFAP, NeuN, MBP, and Iba-1, along with Fluoro-Jade C histofluorescence staining. CHI3L1 was found at meningeal interfaces, showing significant thickening of subpial glial plate. Paradoxically, CHI3L1-positive astrocytes were identified in neuroanatomical locations distant from hemorrhagic foci, where numerous eosinophilic ischemic neurons also exhibited CHI3L1 immunoreactivity. CHI3L1 immunostaining extended into white matter tracts and highlighted various phagocytic or activated microglia forms after delayed surgical decompressions. Given these findings, we advise against using CHI3L1 as a reactive astrogliosis marker due to its expression in multiple cell types, including astrocytes, neurons, oligodendrocytes, ependymocytes, leptomeningeal cells, microglia, and blood vessels. This non-selective response underscores the potential for CHI3L1 elevation patterns in biofluids to reflect the overall lesion burden extent.

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

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

Cross-species single-cell transcriptomics reveals neuronal similarities and heterogeneity in amniote pallium.

The amniote pallium, a vital component of the forebrain, exhibits considerable evolutionary divergence across species and mediates diverse functions, including sensory processing, memory formation, and learning. However, the relationships among pallial subregions in different species remain poorly characterized, particularly regarding the identification of homologous neurons and their transcriptional signatures. In this study, we utilized single-nucleus RNA sequencing to examine over 130 000 nuclei from the macaque ( Macaca fascicularis) neocortex, complemented by datasets from humans ( Homo sapiens), mice ( Mus musculus), zebra finches ( Taeniopygia guttata), turtles ( Chrysemys picta bellii), and lizards ( Pogona vitticeps), enabling comprehensive cross-species comparison. Results revealed transcriptomic conservation and species-specific distinctions within the amniote pallium. Notable similarities were observed among cell subtypes, particularly within PVALB + inhibitory neurons, which exhibited species-preferred subtypes. Furthermore, correlations between pallial subregions and several transcription factor candidates were identified, including RARB, DLX2, STAT6, NR3C1, and THRB, with potential regulatory roles in gene expression in mammalian pallial neurons compared to their avian and reptilian counterparts. These results highlight the conserved nature of inhibitory neurons, remarkable regional divergence of excitatory neurons, and species-specific gene expression and regulation in amniote pallial neurons. Collectively, these findings provide valuable insights into the evolutionary dynamics of the amniote pallium.

Syngap1 promotes cognitive function through regulation of cortical sensorimotor dynamics

Perception, a cognitive construct, emerges through sensorimotor integration (SMI). The genetic mechanisms that shape SMI required for perception are unknown. Here, we demonstrate in mice that expression of the autism/intellectual disability gene, Syngap1, in cortical excitatory neurons is required for the formation of somatomotor networks that promote SMI-mediated perception. Cortical Syngap1 expression was necessary and sufficient for setting tactile sensitivity, sustaining tactile object exploration, and promoting tactile learning. Mice with deficient Syngap1 expression exhibited impaired neural dynamics induced by exploratory touches within a cortical-thalamic network that promotes attention and perception. Disrupted neuronal dynamics were associated with circuit-specific long-range synaptic connectivity abnormalities. Our data support a model where autonomous Syngap1 expression in cortical excitatory neurons promotes cognitive abilities through the assembly of long-range circuits that integrate temporally-overlapping sensory and motor signals, a process that promotes perception and attention. These data provide systems-level insights into the robust association between Syngap1 expression and cognitive ability.

Rare Variant Analyses in Ancestrally Diverse Cohorts Reveal Novel ADHD Risk Genes.

Attention-deficit/hyperactivity disorder (ADHD) is a highly heritable neurodevelopmental disorder, but its genetic architecture remains incompletely characterized. Rare coding variants, which can profoundly impact gene function, represent an underexplored dimension of ADHD risk. In this study, we analyzed large-scale DNA sequencing datasets from ancestrally diverse cohorts and observed significant enrichment of rare protein-truncating and deleterious missense variants in highly evolutionarily constrained genes. This analysis identified 15 high-confidence ADHD risk genes, including the previously implicated KDM5B . Integrating these findings with genome-wide association study (GWAS) data revealed nine enriched pathways, with strong involvement in synapse organization, neuronal development, and chromatin regulation. Protein-protein interaction analyses identified chromatin regulators as central network hubs, and single-cell transcriptomic profiling confirmed their expression in neurons and glial cells, with distinct patterns in oligodendrocyte subtypes. These findings advance our understanding of the genetic architecture of ADHD, uncover core molecular mechanisms, and provide promising directions for future therapeutic development.

Histone Methyltransferase G9a in Primary Sensory Neurons Promotes Inflammatory Pain and Transcription of Trpa1 and Trpv1 via Bivalent Histone Modifications.

Transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) channels are crucial for detecting and transmitting nociceptive stimuli. Inflammatory pain is associated with sustained increases in TRPA1 and TRPV1 expression in primary sensory neurons. However, the epigenetic mechanisms driving this upregulation remain unknown. G9a (encoded by Ehmt2) catalyzes H3K9me2 and generally represses gene transcription. In this study, we found that intrathecal administration of UNC0638, a specific G9a inhibitor, or G9a-specific siRNA, substantially reduced complete Freund's adjuvant (CFA)-induced pain hypersensitivity. Remarkably, CFA treatment did not induce persistent pain hypersensitivity in male and female mice with conditional Ehmt2 knockout in dorsal root ganglion (DRG) neurons. RNA sequencing and quantitative PCR analyses showed that CFA treatment caused a sustained increase in mRNA levels of Trpa1 and Trpv1 in the DRG. Ehmt2 knockout in DRG neurons elevated baseline Trpa1 and Trpv1 mRNA levels but notably reversed CFA-induced increases in their expression. Chromatin immunoprecipitation revealed that CFA treatment reduced G9a and H3K9me2 levels while increasing H3K9ac and H3K4me3-activating histone marks-at Trpa1 and Trpv1 promoters in the DRG. Strikingly, conditional Ehmt2 knockout in DRG neurons not only diminished H3K9me2 but also reversed CFA-induced increases in H3K9ac and H3K4me3 at Trpa1 and Trpv1 promoters. Our findings suggest that G9a in primary sensory neurons constitutively represses Trpa1 and Trpv1 transcription under normal conditions but paradoxically enhances their transcription during tissue inflammation. This latter action accounts for inflammation-induced TRPA1 and TRPV1 upregulation in the DRG. Thus, G9a could be targeted for alleviating persistent inflammatory pain.Significance statement This study demonstrates for the first time that G9a, a histone methyltransferase, in sensory neurons is crucial for the persistent pain development following inflammation. Inhibiting or knockdown of G9a at the spinal cord level reduced inflammation-induced pain hypersensitivity. Remarkably, mice lacking G9a in sensory neurons failed to develop persistent pain hypersensitivity after inflammation. Ablating G9a in sensory neurons increased baseline expression of the TRPA1 and TRPV1 ion channels but reversed their upregulation induced by inflammation. Additionally, G9a deletion blocked the inflammation-driven enrichment of activating histone marks at Trpa1 and Trpv1 promoters. These findings highlight a dual role of G9a in sensory neurons: suppressing Trpa1 and Trpv1 transcription under normal conditions while promoting their transcription during inflammation through bivalent histone modifications.

Multilayer regulation underlies the functional precision and evolvability of the olfactory system.

Sensory neurons must be reproducibly specified to permit accurate neural representation of external signals but also able to change during evolution. We studied this paradox in the Drosophila olfactory system by establishing a single-cell transcriptomic atlas of all developing antennal sensory lineages, including latent neural populations that normally undergo programmed cell death (PCD). This atlas reveals that transcriptional control is robust, but imperfect, in defining selective sensory receptor expression. A second layer of precision is afforded by the intersection of expression of functionally-interacting receptor subunits. A third layer is defined by stereotyped PCD patterning, which masks promiscuous receptor expression in neurons fated to die and removes "empty" neurons lacking receptors. Like receptor choice, PCD is under lineage-specific transcriptional control; promiscuity in this regulation leads to previously-unappreciated heterogeneity in neuronal numbers. Thus functional precision in the mature olfactory system belies developmental noise that might facilitate the evolution of sensory pathways.

Janus Kinase 2/Signal Transducer and Activator of Transcription 3/Cyclooxygenase 2 Signaling Pathway Mediates the Effect of Central Angiotensin II on the Elevation of Rostral Ventrolateral Medulla Prostaglandin E2-Induced Oxidative Stress in Hypertension.

Prostaglandin E2 (PGE2) in the rostral ventrolateral medulla (RVLM) has been recognized as a pivotal pressor substance in hypertension, yet understanding of its effects and origins in the RVLM remains largely elusive. This study aimed to elucidate the pivotal enzymes and molecular mechanisms underlying PGE2 synthesis induced by central Ang II (angiotensin II) and its implications in the heightened oxidative stress and sympathetic outflow in hypertension. RVLM microinjections of PGE2 and Tempol were administered in Wistar-Kyoto rats. Intracisternal drug delivery and adeno-associated viral vectors microinjection were used in both Wistar-Kyoto rats and spontaneous hypertensive rats to modulate the function of Ang II, PGE2 receptor 3, and expression of COX2 (cyclooxygenase 2). Microinjection of PGE2 into the RVLM significantly augmented sympathetic activity (25.380±1.566%) and oxidative stress level, whereas intracisternal infusion of a prostaglandin E receptor 3 antagonist attenuated sympathetic activity in both spontaneous hypertensive rats and Ang II-induced hypertensive rats. Furthermore, Ang II treatment upregulated COX2 expression in RVLM neurons (1.000±0.112 versus 1.506±0.370 fold change), with no significant effect on other enzymes involved in PGE2 synthesis. Additionally, inhibition of the JAK2/STAT3 (Janus kinase 2/signal transducer and activator of transcription 3) signaling pathway nullified Ang II-mediated elevation of COX2 expression, as evidenced by phosphorylated STAT3 binding to the COX2 sequence in PC12 cells. Central Ang II induces the accumulation of RVLM PGE2 through the neuronal AT1R (angiotensin type 1 receptor)/JAK2/STAT3/COX2 pathway, thereby promoting oxidative stress, augmenting sympathetic outflow, and contributing to essential hypertension.

Neuroanatomical and functional substrates of the short video addiction and its association with brain transcriptomic and cellular architecture.

Short video addiction (SVA) has emerged as a growing behavioral and social issue, driven by the widespread use of digital platforms that provide highly engaging, personalized, and brief video content. We investigated the neuroanatomical and functional substrates of SVA symptoms, alongside brain transcriptomic and cellular characteristics, using Inter-Subject Representational Similarity Analysis (IS-RSA) and transcriptomic approaches. Behaviorally, we found that dispositional envy was associated with SVA. Structurally, SVA was positively correlated with increased morphological volumes in the orbitofrontal cortex (OFC) and bilateral cerebellum. Functionally, the dorsolateral prefrontal cortex (DLPFC), posterior cingulate cortex (PCC), cerebellum, and temporal pole (TP) exhibited heightened spontaneous activity, which was positively correlated with SVA severity. Transcriptomic and cellular analyses also showed specific genes linked to gray matter volume (GMV) associated with SVA, with predominant expression in excitatory and inhibitory neurons. These genes showed distinct spatiotemporal expression patterns in the cerebellum during adolescence. This study offers a comprehensive framework integrating structural, functional, and neurochemical evidence to highlight the neural-transcriptomic underpinnings of SVA symptoms in a non-clinical population.

The chromatin remodeler ADNP regulates neurodevelopmental disorder risk genes and neocortical neurogenesis

Although chromatin remodelers are among the most important risk genes associated with neurodevelopmental disorders (NDDs), the roles of these complexes during brain development are in many cases unclear. Here, we focused on the recently discovered ChAHP chromatin remodeling complex. The zinc finger and homeodomain transcription factor ADNP is a core subunit of this complex, and de novo ADNP mutations lead to intellectual disability and autism spectrum disorder. However, germline Adnp knockout mice were previously shown to exhibit early embryonic lethality, obscuring subsequent roles for the ChAHP complex in neurogenesis. To circumvent this early developmental arrest, we generated a conditional Adnp mutant allele. Using single-cell transcriptomics, cut&run-seq, and histological approaches, we show that during neocortical development, Adnp orchestrates the production of late-born, upper-layer neurons through a two-step process. First, Adnp is required to sustain progenitor proliferation specifically during the developmental window for upper-layer cortical neurogenesis. Accordingly, we found that Adnp recruits the ChAHP subunit Chd4 to genes associated with progenitor proliferation. Second, in postmitotic differentiated neurons, we define a network of risk genes linked to NDDs that are regulated by Adnp and Chd4. Taken together, these data demonstrate that ChAHP is critical for driving the expansion of upper-layer cortical neurons and for regulating neuronal gene expression programs, suggesting that these processes may potentially contribute to NDD etiology.

Maternal obesity alters histone modifications mediated by the interaction between Ezh2 and Ampk, impairing neural differentiation in the developing embryonic brain cortex.

Neurodevelopmental disorders have complex origins that manifest early during embryonic growth and are associated with intricate gene regulation dynamics. A perturbed metabolic environment such as hyperglycemia or dyslipidemia, particularly due to maternal obesity, poses a threat to the optimal development of the embryonic central nervous system. Accumulating evidence suggests that these metabolic irregularities during pregnancy may alter neurogenesis pathways, thereby predisposing the developing fetus to neurodevelopmental disorders. One primary mechanism through which such disruptions may occur involves changes in histone modifications resulting from fluctuations in the expression of histone-modifying enzymes or the availability of their substrates. Herein, we have used a rat model of maternal obesity induced by a high-fat diet (HFD) before and during gestation to investigate the cellular and molecular repercussions of maternal obesity on embryonic cortical neurogenesis. Maternal obesity impairs neurogenesis by reducing cell proliferation, increasing neuronal marker expression, and shifting development toward astrogliogenesis. Differentially expressed genes (DEGs) revealed disruptions in key developmental signaling pathways and reduced Akt phosphorylation, particularly at E14.5. These changes were associated with epigenetic alterations, mainly the differential expression and phosphorylation of Ezh2 and subsequent changes in global histone modifications. ChIP-seq revealed reduced H3K27me3 at genes upregulated due to maternal obesity, which could have resulted from reduced expression and increased phosphorylation of Ezh2 at Thr311. Interestingly, Ezh2 also showed increased O-GlcNAcylation in HFD embryos along with increased association with Ampk-Thr172 in accordance with previous studies showing that Ampk catalyzes Ezh2-Thr311p. These results suggest that an epigenetic gene regulatory mechanism mediated by Ampk and Ezh2 interactions resulted in reduced H3K27me3 and de-repression of key developmental genes, which could have led to cell fate changes observed in the developing embryo brain cortex due to maternal obesity.

Microglia depletion reduces neurodegeneration and remodels extracellular matrix in a mouse Parkinson’s disease model triggered by α-synuclein overexpression

Chronic neuroinflammation with sustained microglial activation occurs in Parkinson’s disease (PD), yet the mechanisms and exact contribution of these cells to the neurodegeneration remains poorly understood. In this study, we induced progressive dopaminergic neuron loss in mice via rAAV-hSYN injection to cause the neuronal expression of α-synuclein, which produced neuroinflammation and behavioral alterations. We administered PLX5622, a colony-stimulating factor 1 receptor inhibitor, for 3 weeks prior to rAAV-hSYN injection, maintaining it for 8 weeks to eliminate microglia. This chronic treatment paradigm prevented the development of motor deficits and concomitantly preserved dopaminergic neuron cell and weakened α-synuclein phosphorylation. Gene expression profiles related to extracellular matrix (ECM) remodeling were increased after microglia depletion in PD mice, which were further validated on protein level. We demonstrated that microglia exert adverse effects during α-synuclein-overexpression-induced neuronal lesion formation, and their depletion remodels ECM and aids recovery following insult.

Amyloid-β-driven synaptic deficits are mediated by synaptic removal of GluA3-containing AMPA-receptors.

The detrimental effects of oligomeric amyloid-β (Aβ) on synapses are considered the leading cause for cognitive deficits in Alzheimer's disease. However, through which mechanism Aβ oligomers impair synaptic structure and function remains unknown. Here, we used electrophysiology and AMPA-receptor (AMPAR) imaging on mice and rat neurons to demonstrate that GluA3 expression in neurons lacking GluA3 is sufficient to re-sensitize their synapses to the damaging effects of Aβ, indicating that GluA3-containing AMPARs at synapses are necessary and sufficient for Aβ to induce synaptic deficits. We found that Aβ-oligomers trigger the endocytosis of GluA3 and promote its translocation towards endo-lysosomal compartments for degradation. Mechanistically, these Aβ-driven effects critically depend on the PDZ-binding motif of GluA3. A single point mutation in the GluA3 PDZ-binding motif prevented Aβ-driven effects and rendered synapses fully resistant to the effects of Aβ. Correspondingly, proteomics on synaptosome fractions from APP/PS1-transgenic mice revealed a selective reduction of GluA3 at an early age. These findings support a model where the endocytosis and lysosomal degradation of GluA3-containing AMPARs is a critical early step in the cascade of events through which Aβ accumulation causes a loss of synapses.Significance statement Early cognitive symptoms in Alzheimer's disease are considered to be driven by dysfunctional synapses. Studies in animal models for Alzheimer's disease have demonstrated that the preservation of synapses alleviates cognitive symptoms. However, a clinically viable approach to preserve synapses requires a mechanistic understanding of how synaptic function is perturbed. Our study reveals that synapse impairments in Alzheimer models require the synaptic removal and subsequent lysosomal degradation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors that contain subunit GluA3. Preventing this aberrant trafficking of GluA3 leads to the preservation of synapses. This study identifies that the presence of GluA3 determines whether synapses are vulnerable to Alzheimer pathology, thereby deepening our understanding of how synapses are affected in Alzheimer's disease.

Enhanced yield and subtype identity of hPSC-derived midbrain dopamine neuron by modulation of WNT and FGF18 signaling.

While clinical trials are ongoing using human pluripotent stem cell-derived midbrain dopamine (mDA) neuron precursor grafts in Parkinson's disease (PD), current protocols to derive mDA neurons remain suboptimal. In particular, the yield of TH+ mDA neurons after in vivo grafting and the expression of some mDA neuron and subtype-specific markers can be further improved. For example, characterization of mDA grafts by single cell transcriptomics has yielded only a small proportion of mDA neurons and a considerable fraction of contaminating cell populations. Here we present an optimized mDA neuron differentiation strategy that builds on our clinical grade ("Boost") protocol but includes the addition of FGF18 and IWP2 treatment ("Boost+") at the mDA neurogenesis stage. We demonstrate that Boost+ mDA neurons show higher expression of EN1, PITX3 and ALDH1A1. Improvements in both mDA neurons yield and transcriptional similarity to primary mDA neurons is observed both in vitro and in grafts. Furthermore, grafts are enriched in authentic A9 mDA neurons by single nucSeq. Functional studies in vitro demonstrate increased dopamine production and release and improved electrophysiological properties. In vivo analyses show increased percentages of TH+ mDA neurons resulting in efficient rescue of amphetamine induced rotation behavior in the 6-OHDA rat model and rescue of some motor deficits in non-drug induced assays, including the ladder rung assay that is not improved by Boost mDA neurons. The Boost+ conditions present an optimized protocol with advantages for disease modeling and mDA neuron grafting paradigms.

DNA methylation, histone acetylation in the regulation of memory and its modulation during aging.

Memory formation is associated with constant modifications of neuronal networks and synaptic plasticity gene expression in response to different environmental stimuli and experiences. Dysregulation of synaptic plasticity gene expression affects memory during aging and neurodegenerative diseases. Covalent modifications such as methylation on DNA and acetylation on histones regulate the transcription of synaptic plasticity genes. Changes in these epigenetic marks correlated with alteration of synaptic plasticity gene expression and memory formation during aging. These epigenetic modifications, in turn, are regulated by physiology and metabolism. Steroid hormone estrogen and metabolites such as S-adenosyl methionine and acetyl CoA directly impact DNA and histones' methylation and acetylation levels. Thus, the decline of estrogen levels or imbalance of these metabolites affects gene expression and underlying brain functions. In the present review, we discussed the importance of DNA methylation and histone acetylation on chromatin modifications, regulation of synaptic plasticity gene expression and memory consolidation, and modulation of these epigenetic marks by epigenetic modifiers such as phytochemicals and vitamins. Further, understanding the molecular mechanisms that modulate these epigenetic modifications will help develop recovery approaches.