Frontiers in Molecular Neuroscience最新文献

Introduction: While axon regeneration is very limited in the adult central nervous system (CNS) in vivo, this is not the case in the peripheral nervous system (PNS). Indeed, both CNS and PNS neurons can regenerate in vitro although to varying degrees. Given the role of microtubule stabilization in promoting regeneration, we have examined microtubule polymerization during the regeneration of two types of adult neurons in vitro, retinal ganglion cells (RGCs) from the CNS and dorsal root ganglion (DRG) neurons from the PNS.

Methods: In order to compare microtubule dynamics between these cell types, the density, polymerization rate and orientation of microtubules have been analysed during neurite regeneration in both cell types by analysing GFP-tagged Microtubule End Binding 3 (EB3) protein transfected into the neurons.

Results: The density of EB3 comets and the speed of EB3 movement was similar in both cell types, although only one subtype of RGC regenerated sufficiently long neurites for analysis. In the absence of extracellular substances that could inhibit neurite regeneration, the dynamics of the microtubules of the RGC subtype that extend long neurites are very similar to those in DRG neurons. However, some RGCs with very short neurites exhibited EB3 comets that progressed retrogradely. Additionally, live imaging of mitochondria was performed in both neuronal cultures.

Discussion: Regenerating neurites assessed in our study exhibited similar microtubule extension dynamics in both CNS- and PNS-originated neurons. Importantly, the observation that robust neurite outgrowth is restricted to RGC subtypes highlights the need to integrate molecular heterogeinity among RGCs in future studies.

Experimental advancements in neuroscience have identified cellular engrams-ensembles of neurons whose activation is necessary and sufficient for memory retrieval. Synaptic plasticity, including long-term potentiation, is fundamental to memory encoding and recall, but the relationship between learning-induced dendritic spine potentiation and neuron-wide activation remains unclear. In this study, we employed a post-synaptic translation-dependent reporter consistent with potentiation (SA-PSDΔVenus) and a neuronal activation reporter (ESARE-dTurquoise) to determine their spatiotemporal correlation in the mouse hippocampal CA1 following contextual fear conditioning (CFC). SA-PSDΔVenus+ spines were enriched in ESARE-dTurquoise+ neurons, with distribution varying across CA1 layers at different phases of memory: SA-PSDΔVenus+ were more frequent in activated neurons in stratum oriens and stratum lacunosum moleculare after CFC (encoding), while recall-activated neurons showed a larger number of SA-PSDΔVenus+ in the stratum radiatum. These findings demonstrate that the relative weight and spatial distribution of potentiated synaptic inputs to hippocampal CA1 pyramidal neurons change between the encoding and retrieval phases of memory.

Autism is a common childhood disorder, often comorbid with epilepsy. Both autism and epilepsy are highly heterogeneous in terms of disease etiology and frequently co-occur with other neuropsychiatric phenotypes. Advances in genetic sequencing technologies have significantly improved our understanding of the biological pathways involved in these disorders, particularly in genetic epilepsy (GE). One critical pathway involves gamma-aminobutyric acid (GABA), a key neurotrophic signal during early brain development. GABA plays a central role in maintaining neural excitatory-inhibitory balance, and its dysfunction has been implicated in both autism and epilepsy. GABA acts through its receptors and transporters to regulate neuronal signaling, and disruptions in this system can lead to neural circuit abnormalities. Recent studies have identified that mutations in GABA_A receptors and the GABA transporter 1(GAT-1) encoding SLC6A1 result in defective protein folding and retention in the endoplasmic reticulum (ER), leading to impaired proteostasis. This common cellular defect has been observed in a subset of patients with autism and epilepsy, suggesting a shared pathogenic mechanism. We propose that ER retention of mutated proteins and impaired trafficking contribute to disease phenotypes associated with monogenic de novo mutations. Consequently, therapeutic strategies aimed at enhancing protein folding and trafficking, such as the use of chemical or pharmacological chaperones like 4-phenylbutyrate, may provide cross-cutting benefits for both disorders. Our hypothesis highlights the potential for a unified therapeutic approach targeting cellular protein homeostasis in genetically defined subsets of autism and epilepsy.

Enzymes within the cholesterol biosynthesis pathway, particularly those in post-squalene biosynthesis, have been linked to abnormal neurodevelopment. Alterations of individual enzymes manifest unique brain phenotypes, suggesting each enzyme has distinct roles within the mammalian neural cell. However, a comprehensive characterization of cholesterol biosynthesis enzymes to understand these differences has yet to be fully obtained. Therefore, this study aimed to contribute to this growing body of knowledge by characterizing the subcellular localization of the cholesterol biosynthesis enzyme Hydroxysteroid-17-beta7 (Hsd17b7) within a mammalian neural cell line. Using mouse Neuro2a cells, we compared expression patterns between both endogenous Hsd17b7 and GFP-tagged constructs. Using confocal microscopy, we noted Hsd17b7 absence in the Golgi and lysosomes while confirming its presence in the endoplasmic reticulum. Of interest, we also observed co-localization with the nuclear membrane, which had not been established. Upon 24-hour serum deprivation, patterns of Hsd17b7-GFP in differentiated cells were still observed in the cell body, as seen in the undifferentiated cells. However, we also observed evidence of GFP-positive protein localization within MAP2-positive neurites. Co-staining with Hsd17b7 antibody and conjugated Phalloidin further supported the localization of Hsd17b7 within developing neurites. Together, this suggests a potential role for Hsd17b7 within early axons and dendrites, however, further investigation is needed to determine potential implications on neural differentiation.

Parkinson's disease (PD) symptom onset is typically unilateral, which may be related to molecular differences underlying hemispheric vulnerability. Here we sampled prefrontal cortex bilaterally from people with PD and healthy controls and performed RNA-seq on neuronal nuclei to determine hemispheric and disease-related differences. Brain hemispheres were categorized based on whether they corresponded to the side of symptom onset (severe) or the opposite side (moderate) and compared for differences in gene expression. We employed two a priori approaches; first we identified genes differentially expressed between PD and controls and between PD brain hemispheres. Second, we examined the presence of, and correlates to, variations in the asymmetry for some differentially expressed genes. We found large variation among individuals with PD, and so PD stratification by gene expression signature was required for patterns of genetic asymmetry to emerge. For a subset of PD brains, hemispherical variation of CCT gene levels correlated with the side of PD symptom onset. In a mouse model of PD, neurons with α-synuclein inclusions had decreased Cct expression. These results suggest that CCT expression plays a protective role in PD.

Introduction: Chronic inflammatory demyelinating polyneuropathy (CIDP) remains diagnostically challenging, with limited biological markers to aid phenotyping and differential diagnosis, particularly at the CIDP-diabetes mellitus (DM) interface.

Methods: We investigated inflammatory genetic and metabolic readouts in CIDP by integrating interleukin 18 (IL-18) promoter variation with cytokines and short-chain fatty acids (SCFAs). 32 untreated CIDP patients and 15 controls underwent clinical scoring, nerve-conduction studies (NCS), IL-18 genotyping (rs187238, rs1946518, rs1946519), serum cytokine profiling (IL-2, tumor necrosis factor α (TNF-α), IL-18), and SCFA quantification in stool, serum, and cerebrospinal fluid (CSF).

Results: No group-level differences emerged for IL-2, TNF-α, or IL-18 in serum or CSF, and CIDP subgroups (DM+ vs DM-; classical vs atypical) did not differ in NCS severity or electromyography (EMG) denervation. In contrast, IL18 promoter variation showed various associations: rs1946518 G allele correlated with peroneal nerve shorter compound motor action potential (CMAP) distal latency and lower ulnar nerve sensory nerve action potential (SNAP) amplitude. Additionally, carriers of the rs187238 C allele showed significantly higher CSF protein concentrations, whereas the rs1946518 G allele was associated with a trend toward lower CSF protein levels. Moreover, the rs187238 C and rs1946518 T alleles were associated with lower CSF butyrate levels. A haplotype analysis indicated that GGG (rs187238, rs1946518, rs1946519) aligned with shorter peroneal nerve CMAP distal latency, lower disability (INCAT), and a lower CSF protein, whereas CTT associated with higher CSF protein and lower CSF butyrate concentrations. We confirmed the presence of acetate, propionate, and butyrate in human CSF and demonstrated serum-CSF equivalence for these SCFAs, while stool concentrations were higher, as expected.

Discussion: Collectively, IL18 polymorphisms and SCFAs readouts emerge as biologically grounded candidates for patient stratification in CIDP; these findings warrant validation in larger, multicenter cohorts integrating electrophysiology with CSF/serum biomarkers and microbiome profiling.

Arterial hypertension is considered a main risk factor for cognitive impairment and stroke. Although chronic hypertension leads to adaptive changes in the lager cerebral blood vessels which should protect the downstream microvessels, profound changes in the structure and function of cerebral microcirculation were reported in this disease. The structural changes lead to dysregulation of the neurovascular unit and manifest themselves in particular as endothelial dysfunction, disruption of the blood-brain barrier and impairment of neurovascular coupling. The impairment of neurovascular coupling results in inadequate functional hyperemia, which in turn may lead to cognitive decline and dementia. In this review the effects of chronic arterial hypertension on the essential components of neurovascular unit involved in neurovascular coupling such as endothelial cells, astrocytes and pericytes are discussed.

Introduction: Oxidative stress is a central driver of brain aging, impairing cellular function and increasing susceptibility to neurodegenerative diseases. Recent studies suggest that the RNA demethylase FTO regulates N6-methyladenosine (m6A) RNA modification, a key pathway in modulating oxidative stress in the brain. However, the precise mechanisms underlying FTO's role remain unclear. This study examines the neuroprotective potential of MO-I-500, a small-molecule FTO inhibitor, against oxidative stress induced by tert-butyl hydroperoxide (TBHP) in neuron-like SH-SY5Y cells differentiated with retinoic acid and BDNF (dSH-SY5Y).

Methods: dSH-SY5Y cells were treated with MO-I-500 alone for 72 h or with TBHP alone for 24 h. Alternatively, cells were pretreated with 1 μM MO-I-500 for 48 h, followed by co-treatment with MO-I-500 and 25 or 50 μM TBHP for an additional 24 h, for a total treatment duration of 72 h. Cellular metabolism was assessed using a Seahorse XF MitoStress assay, and oxidative stress markers, including ROS and superoxide levels, were quantified with DCFDA and MitoSOX probes. ATP content was measured using a bioluminescence assay.

Results: FTO inhibition by MO-I-500 induced a metabolic shift toward an energy-efficient state, enhancing cellular resilience to oxidative stress. Pretreatment significantly reduced TBHP-induced oxidative damage, lowering intracellular ROS levels and preserving ATP content.

Conclusion: Together with our previous findings demonstrating the protective effects of MO-I-500 in astrocytes and recent studies supporting the importance of astrocyte function in neurodegeneration, these results suggest a dual protective role of MO-I-500 in neurons and astrocytes. This dual action positions MO-I-500 as a promising therapeutic strategy to mitigate oxidative damage and reduce the risk of neurodegenerative diseases, including Alzheimer's disease.

Mutations in α-synuclein (α-syn) and LRRK2 cause familial Parkinson's disease (fPD), yet how these proteins functionally interact remain ambiguous. We previously showed that α-syn undergoes bi-directional transport within axons and influences mitochondrial health, while other studies suggested that LRRK2-G2019S disrupts the axonal transport of autophagic vesicles and mitochondria. Here we tested the hypothesis that α-syn and LRRK2 are functionally linked during axonal transport. Expression of human LRRK2-WT in Drosophila larval nerves caused modest CSP-containing axonal blockages whereas no defects were seen in LRRK2 loss of function mutants in contrast to other proteins directly involved in axonal transport. Surprisingly, fPD mutations in the GTPase (LRRK2-Y1699C) and WD40 (LRRK2-G2385R) domains suppressed axonal blocks compared to LRRK2-WT, while kinase-domain mutant G2019S enhanced them. Reducing kinesin-1 had no effect with LRRK2-WT, but increased axonal transport defects with LRRK2-G2385R suggesting a functional interaction between the LRRK2 WD40 domain and the anterograde transport machinery. Further, co-expression of α-syn with either the GTPase domain or WD40 domain LRRK2 fPD mutants significantly suppressed α-syn-mediated axonal transport defects, decreased stalled α-syn-vesicles, but did not alter α-syn-mediated neuronal cell death. Taken together, these results suggest that while LRRK2 itself may not play an independent role in axonal transport, its GTPase and WD40 domains likely associate functionally with α-syn during transport within axons.