Molecular Brain最新文献

Mapping the neural circuit of a specific neuronal subclass is central to understanding the working mechanism of the brain. Currently, numerous types of transgenic mice expressing Cre recombinase have been engineered and widely used in neuroscience. To map the multilevel inputs into the neural circuit of a specific neuronal subpopulation, a Cre-dependent retrograde trans-multisynaptic tracer must be developed. The vaccine strain of Pseudorabies virus (PRV, Bartha strain) can infect neurons and spread in a retrograde manner in the neural circuit. In this study, we engineered the genome of PRV Bartha strain to prepare two new tracers, PRV676 and PRV829, by replacing the TK gene of PRV with the Cre-dependent expression cassette of the fluorescent protein gene and the TK gene. These two tracers can separately and Cre-dependently express EGFP and mRuby3 and produce progeny viruses in vitro and in vivo, which can help to map the multilevel inputs of a specific neuronal subpopulation expressing Cre. Collectively, our work provides two new tools for neuroscience research.

Elevated plasma homocysteine (Hcy) levels lead to hyperhomocysteinemia, a condition associated with various neurological disorders affecting multiple brain regions, including the hippocampus. In this study, we investigated the effects of exposing cultured rat hippocampal neurons to Hcy concentrations corresponding to mild, moderate, and severe hyperhomocysteinemia. A short 24-hour exposure had minimal effects, whereas prolonged exposure up to 14 days moderately enhanced hippocampal excitability without altering the gene expression of voltage-dependent calcium, sodium, or potassium channels or intracellular calcium levels. These findings suggest that Hcy-induced changes in neuronal excitability may contribute to neuropathologies associated with hyperhomocysteinemia.

Selection of appropriate food is an ability that allows animals to make optimal foraging choices. However, the neural mechanisms that control this food selection remain unclear. The purpose of this study was to investigate the connection between memory and the feeding behavior of Drosophila melanogaster when two sucrose solutions with different concentrations are available. We placed flies into plates with 150 mM and 100 mM sucrose solutions and measured the preference for the 150 mM one. Flies preferred the 150 mM solution over the 100 mM when all 60 wells of the plate were filled with both solutions; this preference decreased when there were only 8 wells with food. Remarkably, prior exposure to a plate with all 60 wells filled with both solutions enhanced the preference for the 150 mM, even when there were only 8 wells with food. We found that the memory-related gene rut and the dopamine D1 receptor on the mushroom body were required to enhance the preference after the prior exposure. These findings show that memory acquired through experiencing both solutions is stored in the mushroom body optimizing the food selection process.

Fear extinction training in rodents decreases fear responses, providing a model for the development of post-traumatic stress disorder therapeutics. Fear memory recall reactivates the consolidated fear memory trace across multiple brain regions, and several studies have suggested that these recall-activated neurons are re-engaged during extinction. However, the molecular mechanisms linking this reactivation to extinction remain largely elusive. Here, we investigated the role of N-Methyl-D-Aspartate receptors (NMDARs) in remote memory recall-activated neurons within the basolateral amygdala and the medial prefrontal cortex during extinction training in mice. We found that Grin1 knockdown in these specific ensembles impaired extinction of remote fear memory, but did not reduce their reactivation during retrieval of the extinguished memory. These data suggest that while reactivation of these neuronal populations persists, their NMDARs are crucial for driving the synaptic plasticity needed to extinguish remote fear memories.

Background: Parkinson's disease (PD), a globally prevalent neurodegenerative disorder, has been implicated with oxidative stress (OS) as a central pathomechanism. Excessive reactive oxygen species (ROS) trigger neuronal damage and may induce disulfidptosis-a novel cell death modality not yet characterized in PD pathogenesis.

Method: Integrated bioinformatics analyses were conducted using GEO datasets to identify PD-associated differentially expressed genes (DEGs). These datasets were subjected to: immune infiltration analysis, gene set enrichment analysis (GSEA), weighted gene co-expression network analysis (WGCNA), intersection analysis of oxidative stress-related genes (ORGs) and disulfidptosis-related genes (DRGs) for functional enrichment annotation. Following hub gene identification, diagnostic performance was validated using independent cohorts. LASSO regression was applied for feature selection, with subsequent experimental validation in MPTP-induced PD mouse models. Single-cell transcriptomic profiling and molecular docking studies were performed to map target gene expression and assess drug-target interactions.

Result: A total of 1615 PD DEGs and 200 WGCNA DEGs were obtained, and the intersection with ORGs and DRGs resulted in 202 DEORGs, 11 DEDRGs, and 5 DED-ORGs (NDUFS2, LRPPRC, NDUFS1, GLUD1, and MYH6). These genes are mainly associated with oxidative stress, the respiratory electron transport chain, the ATP metabolic process, oxidative phosphorylation, mitochondrial respiration, and the TCA cycle. 10 hub genes have good diagnostic value, including in the validation dataset (AUC ≥ 0.507). LASSO analysis of hub genes yielded a total of 6 target genes, ACO2, CYCS, HSPA9, SNCA, SDHA, and VDAC1. In the MPTP-induced PD mice model, the expression of ACO2, HSPA9, and SDHA was decreased while the expression of CYCS, SNCA, and VDAC1 was increased, and the expression of the 5 DED-ORGs was decreased. Additionally, it was discovered that N-Acetylcysteine (NAC) could inhibit the occurrence of disulfidptosis in the MPTP-induced PD model. Subsequently, the distribution of target genes with AUC > 0.7 in different cell types of the brain was analyzed. Finally, molecular docking was performed between the anti-PD drugs entering clinical phase IV and the target genes. LRPPRC has low binding energy and strong affinity with duloxetine and donepezil, with binding energies of -7.6 kcal/mol and - 8.7 kcal/mol, respectively.

Conclusion: This study elucidates the pathogenic role of OS-induced disulfidptosis in PD progression. By identifying novel diagnostic biomarkers (e.g., DED-ORGs) and therapeutic targets (e.g., LRPPRC), our findings provide a mechanistic framework for PD management and lay the groundwork for future therapeutic development.

In mammalian brains, astroglia presence near glutamatergic excitatory synapses has generated the term "tripartite" junctions, based on the close association of astrocytic processes near the active zone formed by presynaptic axonal terminal and postsynaptic dendritic spines. One major function of these astrocytic processes is to take up glutamate that spill out of the synaptic cleft during activity, via glutamate transporters located on astroglial plasma membrane. Comapred to other regions of the brain, the cerebellar Purkinje spines in the molecular layer are virtually completely ensheathed by Bergman glia, a special type of astrocyte, unique to cerebellum. The present electron microscopy study classifies these peri-synaptic astrocytic processes (PAP) ensheathing the Purkinje spine synapses into three types based on structural criteria: (1) Type 1- astrocytic process is situated at the edge of the synaptic cleft immediately next to the synaptic active zone. Under fast perfusion fixation conditions where synapses were under resting states, ~ 58% of the PAP's were scored as Type 1. The occurrence frequency of Type 1 PAP significantly decreased to 25% upon a 5-8 min delay in perfusion fixation, where synapses were under stimulated states. (2) Type 2- astrocytic process covers part of the postsynaptic membrane containing the postsynaptic density (PSD), so that this part of the PSD is separated from its presynaptic terminal. Occurrence frequency of Type 2 PAP's significantly increased from ~ 14% under fast perfusion fixation to 31% upon delayed perfusion fixation, and the average length of the PSD edge covered by astroglia increased from 41 nm to 57 nm upon delayed perfusion fixation. (3) Type 3- astrocytic process is situated some distance away from the active zone, while the presynaptic axon terminal extends to enwrap the spine beyond the active zone. Occurrence frequency of Type 3 PAP's increased from 28 to 43% upon delayed perfusion fixation, and the average length between apposed axon terminal and spine beyond the synaptic cleft significantly increased from 98 to 209 nm upon delayed perfusion fixation. Thus, upon stimulation, the tripartite synaptic junctions undergo dynamic structural changes with the astrocytic processes moving into the open cleft to cover the exposed postsynaptic membrane containing PSD, the presynaptic axon terminals extending to wrap the postsynaptic spine beyond the synaptic cleft. Both structural changes may facilitate glutamate uptake to clear the transmitter spilled out from the synaptic cleft during intense activity and prevent damage from overstimulation.

Klotho, a well-known aging suppressor protein, has been implicated in neuroprotection and the regulation of neuronal senescence. While previous studies have demonstrated its anti-aging properties in human brain organoids, its potential to mitigate neurodegenerative processes triggered by β-amyloid remains underexplored. In this study, we utilised human induced pluripotent stem cells (iPSCs) engineered with a doxycycline-inducible system to overexpress KLOTHO and generated 2D cortical neuron cultures from these cells. These neurons were next exposed to pre-aggregated β-amyloid 1-42 oligomers to model the neurotoxicity associated with Alzheimer's disease. Our data reveal that upregulation of KLOTHO significantly reduced β-amyloid-induced neuronal degeneration and apoptosis, as evidenced by decreased cleaved caspase-3 expression and preservation of axonal integrity. Additionally, KLOTHO overexpression prevented the loss of dendritic branching and mitigated reductions in axonal diameter, hallmark features of neurodegenerative pathology. These results highlight Klotho's protective role against β-amyloid-induced neurotoxicity in human cortical neurons and suggest that its age-related decline may contribute to neurodegenerative diseases such as Alzheimer's disease. Our findings underscore the therapeutic potential of Klotho-based interventions in mitigating age-associated neurodegenerative processes.

Mutations in CACNA1C, the gene encoding Ca_v1.2 voltage-gated calcium channels, are associated with a spectrum of disorders, including Timothy syndrome and other neurodevelopmental and cardiac conditions. In this study, we report a child with a de novo heterozygous missense variant (c.1973T > C; L658P) in CACNA1C, presenting with refractory epilepsy, global developmental delay, hypotonia, and multiple systemic abnormalities, but without overt cardiac dysfunction. Electrophysiological analysis of the recombinant Ca_v1.2 L658P variant revealed profound gating alterations, most notably a significant hyperpolarizing shift in the voltage dependence of activation and inactivation. Additionally, molecular modeling suggested that the L658P mutation disrupts interactions within the IIS5 transmembrane segment, reducing the energy barrier for state transitions and facilitating channel opening at more negative voltages. These findings establish L658P as a pathogenic CACNA1C variant primarily associated with severe neurological dysfunction and expands the phenotypic spectrum of CACNA1C-related disorders.

Adult hippocampal neurogenesis is inhibited by chronic psychological stress and impaired neurogenesis underlies stress-related psychological disorders. We previously reported that chronic restraint stress (CRS) evokes autophagic death of adult hippocampal neural stem cells (NSCs) while NSC-specific deletion of Atg7 prevents death of NSCs. Examination of cognitive ability and mood regulation next day of the termination of stress showed normal hippocampal function in mice deficient of Atg7. However, it was not investigated whether the preservation of NSC pool alleviates hippocampal neuronal alterations. Here, we show that CRS increased c-Fos-positive, activated neurons in the granule cell layer and decreased spine density of CA3 neurons in the hippocampus, and these hippocampal neuronal deficits were prevented by NSC-specific deletion of Atg7. Of note, our observation was conducted right after the termination of CRS. Therefore, our results suggest that the detrimental effects of stress on hippocampal neurons can be buffered by NSCs independent of neurogenesis and NSCs are essential to the hippocampal function both through the neurogenesis-dependent developmental process and by direct regulation of neural activation.