Frontiers in Cellular Neuroscience最新文献

Introduction: Astrocytes are parenchymal cells widely distributed throughout the brain. Beyond their essential functions in healthy tissue, astrocytes exhibit an evolutionarily conserved response to all forms of brain injury, termed astrocytic reactivity. Nevertheless, conceptual understanding of what astrocytic reactivity encompasses and its functional roles remains incomplete and occasionally contentious. Lipopolysaccharide (LPS) is widely used to induce neuroinflammation. In the current study, Histone deacetylase 7 (HDAC7) has been shown to ameliorate LPS-induced neuroinflammation and mitigate astrocytic reactivity.

Methods: We overexpressed HDAC7 using viral vectors and generated primary astrocytes from Hdac7 ^flox/flox mice to achieve astrocyte-specific HDAC7 knockout. Subsequently, we assessed astrocytic reactivity and detected the expression of the Interferon regulatory factor 3 (IRF3)/cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway.

Results: HDAC7 has been implicated in inflammatory regulation, but its role in astrocyte reactivity and the underlying mechanisms remain unclear. Here, we demonstrate that HDAC7 deficiency attenuates LPS-induced astrogliosis by suppressing the cGAS/STING signaling axis. LPS stimulation induced robust upregulation of glial fibrillary acidic protein (GFAP), complement component 3 (C3), and pro-inflammatory cytokines (TNF-α, IL-6) in WT astrocytes, which was significantly blunted in HDAC7 knockout astrocytes. Conversely, lentiviral overexpression of HDAC7 in WT astrocytes exacerbated IRF3/cGAS/STING pathway activation, as validated by Western blot analysis showing upregulated cGAS, STING and IRF3 expression. Pharmacological activation of the STING pathway in astrocytes restored pro-inflammatory cytokine expression and reactive marker levels, indicating pathway dependence.

Discussion: Our results delineate a novel HDAC7/IRF3/cGAS/STING signaling axis that governs astrocyte reactivity. This discovery provides a crucial cellular neurophysiological mechanism by which astrocytes integrate inflammatory signals and subsequently modulate the central nervous system microenvironment. Targeting HDAC7, therefore, represents a therapeutic strategy to mitigate neuroinflammation by specifically correcting this aberrant cell-physiological state of astrocytes, ultimately preserving neural circuit function.

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition with unknown etiology. Currently, the role of post-transcriptional mechanisms in ASD remains unclear. microRNAs (miRNAs) are small non-coding regulatory RNAs that mediate mRNA destabilization and/or translational repression. To investigate the potential role of miRNAs in ASD, we performed miRNA expression profiling in the hippocampus of the BTBR ASD mouse model and age-matched C57BL/6 J mice. Alongside, we analyzed the BTBR hippocampal transcriptomic profile to identify differentially expressed transcripts (DETs). By integrating differentially expressed miRNA (DEmiRNA) and DET lists, we discovered mRNA transcripts that are putative targets of BTBR DEmiRNAs and exhibit an anti-correlated differential expression in the BTBR hippocampus. These interactions suggest potential regulatory networks related to gene transcription regulation, and synaptic structure and function relevant for ASD. These include miR-200 family members, miR-200a-3p, miR-200b-3p, miR-200c-3p, and miR-429, and the experimentally validated target, the transcription factor Zeb2. Moreover, we identified a set of non-canonical interactions characterized by extensive pairing between BTBR DEmiRNAs and DETs, potentially triggering target-directed miRNA degradation (TDMD). Our findings support a role for miRNA dysregulation in the pathophysiology of ASD.

Exposure to traumatic stress can lead to psychopathology, including post-traumatic stress disorder (PTSD), but may also cause inflammation and cardiovascular dysfunction. Clinical evidence suggests that exposure to traumatic stress, independent of psychopathology development, may be sufficient to induce pathophysiological sequelae, but this has not been thoroughly investigated. Using a novel model of repeated social defeat stress (RSDS) that allows for both sexes, we explored links between the behavioral and physiological consequences of this paradigm. RSDS was sufficiently able to elevate systemic inflammation in both male and female mice, with no observed sex differences. RSDS also induced a heightened blood pressure sensitization response to low dose exogenous angiotensin II (AngII), suggesting the model was also sufficient in generating cardiovascular pathology. Interestingly, the RSDS-induced sensitization to AngII was completely abrogated in mice lacking T-lymphocytes (i.e., Rag2^-/- mice). Of note, Rag2^-/- mice demonstrated similar pro-social and anxiety-like behavior to wild-type mice, inferring that (1) differences in these behavioral outcomes do not explain the loss of RSDS-induced AngII sensitization in Rag2^-/- mice and (2) T-lymphocytes do not appear to impact these specific RSDS-induced behaviors. Indeed, intra-animal correlations demonstrate a tight association between the inflammatory and cardiovascular consequences post-RSDS, but no associations between these parameters with behavior. Together, our data suggest that exposure to traumatic stress, independent of psychopathology, is sufficient to induce pathophysiology. These findings have significant clinical implications, specifically for individuals who have experienced traumatic stress without the development of psychopathology, as this overlooked population may have similar risks of developing somatic diseases.

Early-life stress (ELS) and enrichment often have opposing effects on long-term cognitive abilities. Deprivation, such as institutionalized care during early childhood neurodevelopmental periods, results in lifelong working memory and recall deficits. In contrast, enrichment facilitates new learning and slows cognitive decline due to aging and neurodegenerative diseases. Similarly, in rodent models, enrichment facilitates learning whereas ELS induces prominent spatial memory deficits. Environmental enrichment (EE) and ELS can cause opposing changes in hippocampal structure (e.g., shifts in synaptic density) that largely depend on experimental conditions. However, it remains untested whether EE can rescue the behavioral disruptions caused by ELS and how this would impact the hippocampus at advanced ages. To address this, we conducted a longitudinal study on ELS mice, extensively training them on a cognitive enrichment track (ET) or an exercise alone control track (CT). After this, the mice underwent repeated memory testing followed by brain extraction for anatomical analysis of their hippocampus. We found that ET reversed spatial memory deficits at 6, 13, and 20 months and reduced the number of dentate gyrus (DG) to CA3 synapses. Surprisingly, this reduction occurred at excitatory MF synapses surrounding CA3 somas in the stratum pyramidale-a layer not typically associated with MF terminals. Collectively, these findings suggest that cognitive enrichment during early adulthood may reverse ELS-induced spatial memory deficits by adjusting synaptic connectivity between the DG and CA3.

Neurodegenerative diseases such as Alzheimer's, Parkinson's, Huntington's, ALS, and spinocerebellar ataxia are becoming more prevalent as populations age, posing major global health challenges. Despite decades of research, effective treatments that halt or reverse these conditions remain elusive. Aging is the most significant risk factor in the development of these diseases, intertwining with molecular processes like DNA damage, mitochondrial dysfunction, and protein aggregation. Recent advances in gene-editing technologies, particularly CRISPR-Cas9, are beginning to shift the therapeutic landscape. This revolutionary tool allows for precise correction of genetic mutations associated with neurodegeneration, offering the potential for disease modification rather than symptom management alone. In this review, we explore how CRISPR-Cas9 is being leveraged to target key genes implicated in various neurodegenerative conditions and how it may overcome barriers posed by aging biology. We also examine the delivery systems and safety challenges that must be addressed before clinical application. With continued progress, CRISPR-Cas9 could mark a turning point in our ability to treat or even prevent age-related neurological decline.

Sustained synaptic transmission requires the continuous replenishment of released synaptic vesicles (SVs). This process is particularly critical in neuronal circuits that operate at high rates and with high temporal precision, such as those in the auditory brainstem. Here, we investigated the effect of SV (re-)filling on inhibitory synapses between the medial nucleus of the trapezoid body (MNTB) and the lateral superior olive (LSO). These synapses transmit information with high speed and fidelity, properties essential for auditory computations such as sound localization. We specifically examined the role of the vacuolar ATPase (V-ATPase), a proton pump that acidifies the SV lumen to enable neurotransmitter loading. Using patch-clamp recordings in acute mouse slices, we assessed synaptic function under control conditions and during continuous V-ATPase inhibition with bafilomycin or folimycin. Contrary to our initial hypothesis, pharmacological inhibition caused only moderate impairment of sustained transmission. Even under high drug concentrations and intense stimulation (e.g., 100 Hz for 4 min), steady-state responses declined only to ~33% of control. Similar reductions were observed in the replenishment rate, the size of the readily releasable pool, and the cumulative eIPSC amplitude. Quantal size decreased gradually, reaching ~70% of control. Recovery from synaptic depression persisted in the presence of V-ATPase blockade, although it was less efficient. Together, these findings indicate that MNTB-LSO synapses are relatively resistant to V-ATPase inhibition, suggesting that SV replenishment does not rely solely on V-ATPase activity. Alternative acidification mechanisms may contribute, and among potential candidates, the Na⁺/H⁺ exchanger isoform NHE6 showed strong immunoreactivity in glycinergic MNTB axon terminals contacting LSO somata. This identifies NHE6 as a promising target for future investigation.

Occupational noise-induced hearing loss (NIHL) is linked to the overproduction of mitochondrial reactive oxygen species after noise exposure. This cross-sectional study investigated the relationship between mitochondrial DNA (mtDNA) D-loop region methylation and oxidative stress in 150 participants divided into three age and sex matched groups: a control group (n = 50, workers without noise exposure and with normal hearing), an exposed group (n = 50, workers with significant noise exposure but normal hearing), and a case group (n = 50, workers diagnosed with NIHL). The subjects among groups were matched for sex and age to control confounding factors. Methylation levels of the mtDNA D-loop region were determined by the quantitative PCR following bisulfite conversion, while mitochondrial DNA copy number (mtDNA-CN) was assessed using the real-time PCR. Oxidative stress markers-including superoxide dismutase (SOD), glutathione peroxidase (GPX), total antioxidant status (TAS), and malondialdehyde (MDA)-were quantified via substrate-specific assays, ultraviolet enzymatic methods, and colorimetric techniques. Results showed the case group (141.6 ± 46.80 U/mL) showed lower SOD than the control (159.5 ± 18.68 U/mL, p < 0.05) and exposed groups (164.0 ± 15.44 U/mL, p < 0.01), MDA was higher in the case group (232.8 ± 134.5 nmol/mL) than in the control (193.5 ± 84.13 nmol/mL) and exposed groups (187.3 ± 60.76 nmol/mL), with a significant overall difference (F = 3.162, p < 0.05). The case group showed lower methylation [1.205 (0.595, 2.748) %] than both the control [1.710 (0.912, 3.225) %] and exposed groups [1.850 (0.987, 4.093) %] (H = 7.492, p < 0.05). The case group exhibited higher mtDNA-CN levels [397.7 (205.9, 532.1)] compared to both the blank control group [317.4 (234.6, 549.6)] and the exposed group [225.1 (125.3, 445.0)] (H = 9.213, p < 0.05). Methylation levels of the D-loop region were positively correlated with SOD and negatively correlated with MDA. Mediation analysis indicated that SOD may mediate the relationship between D-loop methylation and bilateral high-frequency hearing thresholds, suggesting an indirect epigenetic regulatory mechanism. These findings imply that noise-induced oxidative imbalance, reflected by reduced SOD, may lead to D-loop hypomethylation, contributing to the development of NIHL. These methylation sites may serve as preliminary biomarkers for further research on preventive strategies.