Frontiers in Cellular Neuroscience最新文献

Variants in genes encoding for voltage-gated K⁺ (Kv) channels are frequent cause of drug-resistant pediatric epilepsies. Obtaining a molecular diagnosis gives the opportunity to assess the efficacy of pharmacological strategies based on in vitro features of mutant channels. In this retrospective observational study, we selected patients with drug-resistant pediatric epilepsies caused by variants in potassium channel encoding genes, followed at the Fondazione IRCCS Istituto Neurologico Carlo Besta of Milan, Italy. After the experimental characterization of variants' functional properties in transiently transfected Chinese Hamster Ovary (CHO) cells, we identified drugs to be used as pharmacological approaches. We recruited six patients carrying different missense variants in four Kv channels (Kv7.2, Kv7.3, Kv3.1, and K_Na1.1). In vitro experiments demonstrated that variants in Kv7 channels induced loss-of-function (LoF) effects, while those affecting Kv3.1 or K_Na1.1 led to gain-of-function (GoF). Moreover, we found that the Kv7 channels activator gabapentin was able to revert the LoF effects caused by Kv7.2/Kv7.3 variants, and the potassium channel-blocker fluoxetine counteracted the GoF effects in Kv3.1 or K_Na1.1 variants. According to experimental data, patients carrying Kv7 variants were treated with gabapentin. While this treatment resulted successful in two patients (#1, Kv7.2 G310S variant; #3, Kv7.3 V359L + Kv7.3 D542N), it resulted detrimental in the remaining case (#2, Kv7.2 D535E), requiring drug withdrawal. The application in vivo of fluoxetine to counteract GoF effects induced by Kv3.1 or K_Na1.1 variants determined a significant reduction of both seizure frequency and behavior disturbances in patient #4 (Kv3.1 V425M), and in both subjects carrying K_Na1.1 variants (#5, S937G and #6, R262Q). However, for the latter case, this drug was halted due to severe behavioral side effects. For most of the patients herein reported, pharmacological strategies, selected according to the in vitro functional properties of Kv-channels pathogenic variants, resulted in a significant improvement of both epileptic and cognitive features.

The transmembrane protein Synapse Differentiation Induced Gene 4 (SynDIG4), also known as Proline-rich transmembrane protein 1 (PRRT1), is an AMPA-type glutamate receptor (AMPAR) auxiliary factor that is necessary for maintaining extra-synaptic pools of GluA1. Loss of SynDIG4, and the subsequent decrease in extra-synaptic GluA1, has been found to significantly impact synaptic plasticity in the hippocampus. However, how SynDIG4 establishes and maintains these pools is unclear. Previous studies suggested that endocytic machinery is important for maintaining a pool of mobile surface AMPARs, and that proteins associated with such cellular machinery are critical for proper protein trafficking and internalization. Given that SynDIG4 co-localizes with GluA1 in early and recycling endosomes in cultured hippocampal neurons, we sought to identify the sorting signals that target SynDIG4 to endosomes to further elucidate the role of SynDIG4 in GluA1 trafficking. In this study, we report that SynDIG4 possesses a YxxΦ sorting motif, 178-YVPV-181, responsible for binding to the AP-2 complex cargo-sorting subunit μ2. This motif appears critical for proper SynDIG4 internalization, as SynDIG4 mutant 178-AVPA-181, which disrupts binding to μ2, induces aberrant SynDIG4 accumulation at the plasma-membrane of heterologous cells and primary rat hippocampal neurons. We also show that SynDIG4 mutants lacking an endocytic signal co-localize with GluA1 but less so with GluA2 on the surface of heterologous cells. Furthermore, we show that another family member, SynDIG1, is enriched in the trans-Golgi network (TGN) and can traffic between the TGN and plasma membrane. We have identified a non-canonical μ2 binding sequence in SynDIG1 that induces aberrant accumulation at the plasma membrane of heterologous cells and primary rat hippocampal neurons, suggesting a conserved role for μ2-mediated endocytosis within the SynDIG family. These results provide important insight into the mechanisms by which SynDIG proteins are targeted to endosomal compartments as a step in understanding SynDIG-mediated regulation of AMPAR trafficking.

Understanding cortical inhibition and its diverse roles remains a key challenge in neurophysiological research. Traditionally, inhibition has been recognized for controlling the stability and rhythmicity of network dynamics, or refining the spatiotemporal properties of cortical representations. In this perspective, we propose that specific types of interneurons may play a complementary role, by modulating the computational properties of neural networks. We review experimental and theoretical evidence, mainly from rodent sensory cortices, that supports this view. Additionally, we explore how dysfunctions in these interneurons may disrupt the network's ability to switch between computational modes, impacting the flexibility of cortical processing and potentially contributing to various neurodevelopmental and psychiatric disorders.

Introduction: Melanin-concentrating hormone (MCH) neurons are essential regulators of energy and glucose homeostasis, sleep-wake behaviors, motivation, learning and memory. These neurons are anatomically distributed across the medial (MH) and lateral hypothalamus (LH), and the adjacent zona incerta (ZI), which may represent functional subgroups with distinct connectivity with different brain regions. Furthermore, MCH neurons can be classified according to co-expression of neuropeptides, such as cocaine and amphetamine- regulated transcript (CART).

Methods: To identify functional similarities and differences of MCH subpopulations, we characterized their intrinsic electrophysiological properties using whole cell current clamp recording on acute brain slices from male and female mice.

Results: MCH neurons were classified into subgroups according to their anatomical localization in three MCH-rich brain areas: MH, LH and ZI. Among the three brain regions, ZI MCH neurons were the least excitable while LH MCH neurons were the most excitable. Furthermore, grouping MCH neurons according to CART co-expression revealed that MCH/CART- cells are uniquely depolarized and excitable, and display H-currents. These MCH/CART- cells were mainly found in the LH, which may in part explain why LH MCH neurons are more excitable. While some sex differences were found, the majority of parameters investigated were not different.

Discussion: Our results suggest that MCH/CART- cells are electrophysiologically distinct, whereas MCH/CART+ cells are largely similar despite their diffuse distribution in the hypothalamus. It is therefore a combination of intrinsic electrophysiological properties and neurochemical identities, in addition to anatomy and connectivity that are likely to be critical in defining functional subpopulations of MCH neurons.

Stargazin, a transmembrane AMPAR regulatory protein (TARP), plays a crucial role in facilitating the transport of AMPA receptors to the cell surface, stabilising their localisation at synapses and influencing their gating properties. The primary objective of this study was to investigate the effect of the V143L mutation in stargazin, previously linked to intellectual disability, on the interaction between stargazin and AMPA receptors. To achieve this, we conducted a thorough examination of eight distinct molecular dynamics simulations of AMPA receptor-stargazin complexes, each associated with different conductance levels. Through extensive analysis of complex interface structures and dynamics, we revealed that the stargazin V143L mutation had a more pronounced destabilising effect on complexes with lower conductance levels than on the conductive states of the receptor, suggesting a potential association with impaired synaptic transmission in individuals with this mutation.

Objective: Depression is a mental disorder that significantly impairs both physical and mental health. Recent studies have shown that reactive astrogliosis have gained significant attention for their involvement in the pathophysiology of depression. However, there is no bibliometric analysis in this research field. This study aims to provide a comprehensive overview of the knowledge structure and research hotspots regarding the role of astrocytes in the mechanisms and treatment of depression through bibliometric analysis. The scope of the literature review encompasses both basic and clinical research.

Methods: Publications related to astrocytes in depression and treatment from 2014 to 2023 were searched in the Web of Science Core Collection (WoSCC) database. VOSviewer, CiteSpace, and the R package "bibliometrix" were used to conduct this bibliometric analysis.

Results: From 2014 to 2023, a total of 1,502 documents from 78 countries on astrocytes in depression and treatment were analyzed from 169 journals, with the most co-cited journals being the Journal of Neuroscience and PNAS. China Medical University was the most productive institution. The analysis identified key authors like Verkhratsky Alexei and Baoman Li, and major co-cited references by Rajkowska and Liddelow. Keywords such as "synaptic plasticity," "astrocytes," and "neuroinflammation" revealed research trends focusing on molecular mechanisms, gut microbiota, and inflammation.

Conclusion: This is the first bibliometric study to comprehensively summarize the research trends and advancements regarding astrocytes in depression and its treatment. Through this bibliometric analysis, we aim to enhance the understanding of the significance of astrocytes in depression research and provide new perspectives and insights for future investigations. We hope that this study will facilitate a broader integration of basic and clinical research, offering novel approaches for the treatment of depression.

Autism spectrum disorder (ASD) is characterized by social deficits and restricted behaviors, with developmental defects in GABAergic circuits proposed as a key underlying etiology. Here, we introduce the V-Y assay, a novel space preference test in which one arm of the Y-maze is initially hidden and later revealed as a novel space. Using an ASD mouse model with FOXG1 haploinsufficiency, which exhibits ASD-like social impairments that can be either exacerbated or ameliorated by GABAergic circuit manipulations, we observed impaired novel space preference and exploratory behavior in the V-Y assay. Interestingly, unlike social phenotypes, novel space preference was initially established by 3 weeks of age but regressed by 6 weeks. Furthermore, alterations in GABAergic signaling via Gad2 mutation did not affect novel space preference, in contrast to their impact on social behaviors. These findings reveal that the regression of novel space preference in ASD follows a distinct developmental trajectory from GABA-driven social impairments, providing new insights into the mechanisms underlying ASD.

Infections impacting the central nervous system (CNS) constitute a substantial predisposing factor for the emergence of epileptic seizures. Given that epilepsy conventionally correlates with hippocampal sclerosis and neuronal degeneration, a potentially innovative avenue for therapeutic intervention involves fostering adult neurogenesis, a process primarily occurring within the subgranular zone of the dentate gyrus (DG) through the differentiation of neural stem cells (NSC). While experimental seizures induced by chemoconvulsants or electrical stimulation transiently enhance neurogenesis, the effects of encephalitis and the resultant virus-induced seizures remain inadequately understood. Thus, this study employed the Theiler's Murine Encephalomyelitis Virus (TMEV) model of virus-induced seizures in adult C57BL/6J mice to investigate the impact of infection-induced seizures on neurogenesis at three distinct time points [3, 7, and 14 days post-infection (dpi)]. Immunohistochemical analysis revealed a reduction in the overall number of proliferating cells post-infection. More notably, the specific cell types exhibiting proliferation diverged between TMEV and control (CTR) mice: (1) Neuronal progenitors (doublecortin, DCX⁺) were almost entirely absent at 3 dpi in the dorsal DG. They resumed proliferation at 14 dpi, but, did not recover to CTR levels, and displayed aberrant migration patterns. (2) The number of proliferating NSCs significantly decreased within the dorsal DG of TMEV mice at 14 dpi compared to CTR, while (3) a heightened population of proliferating astrocytes was observed. Most observed changes were not different between seizing and non-seizing infected mice. In summary, our findings demonstrate that viral infection rapidly depletes neuronal progenitor cells and causes aberrant migration of the remaining ones, potentially contributing to hyperexcitability. Additionally, the increased differentiation toward glial cell fates in infected mice emerges as a possible additional pro-epileptogenic mechanism.

Protein lactylation is a new form of post-translational modification that has recently been proposed. Lactoyl groups, derived mainly from the glycolytic product lactate, have been linked to protein lactylation in brain tissue, which has been shown to correlate with increased neuronal excitability. Ischemic stroke may promote neuronal glycolysis, leading to lactate accumulation in brain tissue. This accumulation of lactate accumulation may heighten neuronal excitability by upregulating protein lactylation levels, potentially triggering post-stroke epilepsy. Although current clinical treatments for seizures have advanced significantly, approximately 30% of patients with epilepsy remain unresponsive to medication, and the prevalence of epilepsy continues to rise. This study explores the mechanisms of epilepsy-associated neuronal death mediated by lactate metabolism and protein lactylation. This study also examines the potential for histone deacetylase inhibitors to alleviate seizures by modifying lactylation levels, thereby offering fresh perspectives for future research into the pathogenesis and clinical treatment of epilepsy.

Introduction: In vitro, primary rat oligodendrocytes (OLs) are widely used for research on OL development, physiology, and pathophysiology in demyelinating diseases such as multiple sclerosis. Primary culture methods for OLs from rats have been developed and improved over time, but there are still multiple aspects in which efficiency can be boosted.

Methods: To make use of excess oligodendrocyte progenitor cells (OPCs) from primary cultures, a cryopreservation process utilizing a commercially available serum-free cryopreservation medium was established to passage and freeze OPCs at -80°C for later use.

Results: Cryopreserved OPCs stored for up to 6 months were viable, and retained their OL lineage purity of ~98%. While OPCs cryopreserved for 3-6 months showed a decrease in cell density after two days of proliferation, ~17% of cryopreserved OPCs maintained the potential for proliferation comparable to control OPCs that had not frozen. After induction of differentiation for four days, ~43% of both control and cryopreserved OPCs differentiated into mature OLs, and when differentiation was induced on aligned nanofibers mimicking axonal structure, myelin sheath-like structures indicative of in vitro myelination was observed in all experimental groups.

Conclusion: The validation of cryopreserved primary OLs as a functionally robust in vitro model can help improve the efficiency of primary OL culture, expand its applications, and reduce the inevitable sacrifice of animals.