Molecular Brain最新文献

Mitochondrial dysfunction and abnormalities in mitochondrial quality control contribute to the development of neurodegenerative diseases. Parkinson's disease is a neurodegenerative disease that causes motor problems mainly due to the loss of dopaminergic neurons in the substantia nigra pars compacta. Axonal mitochondria in neurons reportedly differ in properties and morphologies from mitochondria in somata or dendrites. However, the function and morphology of axonal mitochondria in human dopaminergic neurons remain poorly understood. To define the function and morphology of axonal mitochondria in human dopaminergic neurons, we newly generated tyrosine hydroxylase (TH) reporter (TH-GFP) induced pluripotent stem cell (iPSC) lines from one control and one PRKN-mutant patient iPSC lines and differentiated these iPSC lines into dopaminergic neurons in two-dimensional monolayer cultures or three-dimensional midbrain organoids. Immunostainings with antibodies against axonal and dendritic markers showed that axons could be better distinguished from dendrites of dopaminergic neurons in the peripheral area of three-dimensional midbrain organoids than in two-dimensional monolayers. Live-cell imaging and correlative light-electron microscopy in peripheral areas of midbrain organoids derived from control TH-GFP iPSCs demonstrated that axonal mitochondria in dopaminergic neurons had lower membrane potential and were shorter in length than those in non-dopaminergic neurons. Although the mitochondrial membrane potential did not significantly differ between dopaminergic and non-dopaminergic neurons derived from PRKN-mutant patient lines, these differences tended to be similar to those in control lines. These results were also largely consistent with those of our previous study on somatic mitochondria. The findings of the present study indicate that midbrain organoids are an effective tool to distinguish axonal from dendritic mitochondria in dopaminergic neurons. This may facilitate the analysis of axonal mitochondria to provide further insights into the mechanisms of dopaminergic neuron degeneration in patients with Parkinson's disease.

Sleep is essential for strengthening memory and consolidation. Emerging evidence supports its role in cognitive processes such as rule abstraction and inference. However, how sleep influences logical nongambling probabilistic decision-making has yet to be discovered. We developed a reward-based logical decision task that requires rule use and allows scope for reasoning. The mice were able to discriminate between two contexts with different outcomes. This behavior paradigm teaches mice to make free choices between an option to obtain a high-value probabilistic reward in specific entries and a guaranteed safe, low-value option. This knowledge was acquired through six forced entries to each side in training sessions, and they were then tested on subsequent days. As a hidden rule, they may extend their knowledge during these testing sessions by being allowed to take extra entries. We found that extended sleep deprivation disrupted their logical decisions. Sleep-deprived mice were unable to maintain their previous logical performance, resulting in a significant reduction in the rewards they earned. Rule switching in an updated version of the task eliminated gambling-like behavioral dependence in this novel task. These results suggest that adequate sleep is necessary for applying learned knowledge and engaging in complex cognitive functions, such as reasoning.

Ischemic stroke (IS) is an acute cerebrovascular disease characterized by high incidence and mortality. The mechanism of microglia in the pathogenesis of IS remains unclear. This study aimed to explore the key genes related to microglia in IS and their molecular mechanisms in the pathogenesis. In this study, the transcriptome data of IS were retrieved from public databases. Subsequently, candidate genes were identified through the intersection of microglia-related genes (MGGs) obtained via single-cell annotation and high-dimensional weighted gene co-expression network analysis (hdWGCNA) with differentially expressed genes (DEGs). Next, key genes were determined through protein-protein interaction (PPI) analysis and verification of expression levels. Afterwards, enrichment analysis, variation analysis, construction of regulatory networks, drug prediction, and molecular docking were performed to evaluate the role of key genes in the pathogenesis of IS. Ultimately, the quantitative real-time PCR (qRT-PCR) was applied to confirm the expression levels of DEGs in brain tissues between sham and transient middle cerebral artery occlusion (tMCAO) mice. A total of 1407 DEGs intersected with 100 MGGs, yielding 51 candidate genes. Subsequently, 3 key genes (Cd14, Csf1, and Tlr2) were successfully obtained. The study revealed that these 3 key genes were co-enriched in 4 pathways, such as leishmania infection and ribosomal, and there were differences in the enriched pathways among groups. Notably, the expression of the 3 key genes was regulated by multiple factors, including 32 microRNAs (miRNAs), such as mmu-miR-3072-5p and mmu-miR-3970, and 7 transcription factors (TFs), such as Sp1 and Nfkb1. Meanwhile, these 3 key genes predicted 8 common drugs. Interestingly, Tlr2 and Adapalene exhibited a strong binding affinity (- 9.73 kcal/mol). qRT-PCR analysis revealed significantly elevated mRNA expression levels of Cd14, Csf1, and Tlr2 in tMCAO mice compared to sham-operated controls (p < 0.01). This study identified and validated 3 key genes (Cd14, Csf1, and Tlr2) associated with IS, which may serve as novel targets for IS diagnosis and treatment strategies.

Synucleinopathies are age-related neurological disorders which include dementia with Lewy bodies (DLB), Parkinson's disease (PD), and multiple system atrophy (MSA). A hallmark of these diseases is the pathological accumulation of α-synuclein aggregates, along with sustained neuroinflammatory responses. Recent studies have demonstrated the existence of structurally distinct α-synuclein aggregates in this group of the diseases. While the correlation between specific forms of α-synuclein and distinct pathological characteristics has been extensively studied, their relationship to neuroinflammation remains elusive. Here, we examined the effects of structurally distinct α-synuclein polymorphs on microglial neuroinflammation. Human induced pluripotent stem cells (iPSCs)-derived microglia (iMicroglia, iMG) were treated with α-synuclein polymorphs including EGCG stabilized α-synuclein oligomers (EO), kinetically stable α-synuclein oligomers (KSO), dopamine stabilized α-synuclein oligomers (DO), α-synuclein preformed fibrils (PFF), sonicated α-synuclein preformed fibrils (sPFF), and matured α-synuclein fibrils (Fib). Microglial gene expressions were accessed by transcriptome analysis and Toll-like receptor agonist activities were determined by HEK-Blue TLR reporter assay. Exposures to kinetically stable α-synuclein oligomers and matured α-synuclein fibrils induced the expression of microglial cytokines and chemokines, while other species did not. Microglial transcriptome analysis yielded that all polymorphs commonly induce toll-like receptor (TLR) signaling cascade despite differential transcriptomic phenotypes. Among structurally distinct α-synuclein polymorphs, live cell TLR reporter assay showed that kinetically stable α-synuclein oligomers induce the activities of TLR2 and 4, and sonicated α-synuclein preformed fibril TLR4, relative to the control. These results suggest that structurally distinct α-synuclein polymorphs have likewise distinct neuroinflammatory properties.

The glymphatic system plays a key role in brain waste clearance, but its genetic regulation remains poorly understood. Diffusion Tensor Image Analysis along the Perivascular Space (DTI-ALPS) index is a non-invasive imaging biomarker to asses glymphatic system activity. We integrated mean DTI-ALPS genome-wide association study (GWAS) data from 31,021 individuals of European ancestry with GTEx v8 multi-tissue eQTL data to perform transcriptome-wide association studies (TWAS) using Unified Test for Molecular Signature (UTMOST) and Functional Summary-based Imputation (FUSION). Gene-level associations were further validated by Multi-marker Analysis of Genomic Annotation (MAGMA). Causal inference was conducted using cis-Mendelian randomization (cis-MR) and summary-data-based Mendelian randomization (SMR), while colocalization was applied to provide evidence of strong associations between two traits within a single genetic region, thereby ensuring the stability of the MR conclusions. TWAS identified 17 candidate genes (AGBL5-IT1, CENPA, CGREF1, DNAJC5G, EMILIN1, GCAT, KHK, MAPRE3, OTOF, PLCL1, PREB, RBM43, RFTN2, SERPIND1, SNAP29, TRIOBP, and UCN), among which six protein-coding genes (TRIOBP, MAPRE3, EMILIN1, KHK, GCAT, and CGREF1) were further validated by MAGMA. Cis-MR provided evidence for the causal effects of these six genes, while colocalization supported that the MR conclusions were stable for four of them (TRIOBP, MAPRE3, EMILIN1, and GCAT). Finally, SMR identified three genes (TRIOBP, GCAT, and MAPRE3) that showed consistent and robust associations with DTI-ALPS across multiple tissues. These findings provide statistical evidence for genetic regulation of glymphatic function.

Astrocytes, the most abundant glial cell type in the central nervous system (CNS), are essential for maintaining neural homeostasis, forming gliovascular unit, and modulating synaptic function. However, commonly used astrocytic markers often display regional variability or lack strict specificity, limiting their reliability for consistently identifying astrocytes across brain regions. To address this limitation, we generated a novel transgenic mouse line (AldoC BAC-GFP) that expresses green fluorescent protein (GFP) under the control of the aldolase C (AldoC) promoter using modified bacterial artificial chromosome (BAC) technology. AldoC is an enzyme abundantly expressed in astrocytes. We confirmed that GFP-expressing cells in these mice co-express endogenous AldoC and are co-labeled with established astrocytic markers, thereby validating their astrocytic identity. Importantly, GFP expression was largely restricted to astrocytes throughout diverse brain regions. Moreover, GFP-positive astrocytes in brain slices exhibited the characteristic linear-shaped passive conductance of mature astrocytes. Collectively, these findings demonstrate that AldoC BAC-GFP transgenic mice represent a reliable and broadly applicable model for functional studies of astrocytes in the CNS.

Long-lasting synaptic changes enable memory storage and regulate recall in the brain. Our previous work established that generation of multi-innervated dendritic spines (MISs), spines with typically two excitatory presynaptic inputs, underlies hippocampal memory formation in aged, but not young mice. The identification of MIS generation was done by ultrastructural analysis in hippocampal CA1 stratum radiatum 24 h after contextual fear conditioning (CFC). However, our analysis did not consider multi-spine boutons (MSBs), which were recently shown to increase in complexity (complex MSBs are pre-synaptic boutons connecting with more than two post-synapses) at a later time point after CFC in young age. Therefore, we re-analyzed our three-dimensional electron microscopy images and show that, unexpectedly, MSB complexity, decreases in CA1 stratum radiatum 24 h after CFC. The decrease in MSB complexity occurred both in young and aged mice, indicating that aging has no impact on this synaptic change. Considering that complex MSBs link the activity of multiple postsynaptic neurons, we suggest that after CFC a decrease in MSB complexity may be required for specific memory recall.

Parkinson's disease (PD) is a progressive neurodegenerative disorder marked by the loss of dopaminergic neurons and widespread transcriptomic dysregulation across disease stages. Patients commonly exhibit motor symptoms such as tremors, rigidity, and bradykinesia, alongside non-motor symptoms including depression and cognitive decline. While previous research has largely focused on protein-coding genes, growing attention is being directed toward the regulatory roles of non-coding RNAs in PD pathogenesis-particularly the interplay between circular RNAs (circRNAs) and microRNAs (miRNAs). Emerging evidence indicates that circRNAs can act as competing endogenous RNAs (ceRNAs), modulating gene expression by sequestering miRNAs and thereby mitigating miRNA-mediated repression of target mRNAs. In this study, we performed a dynamic transcriptomic analysis across four PD stages using RNA-seq data to identify differentially expressed circRNA-miRNA-mRNA networks. We constructed stage-specific ceRNA networks by selecting positively co-regulated circRNAs and linear transcripts that were co-expressed exclusively within the same disease stage. Among the upregulated circRNAs with predicted ceRNA activity, circPRDM2 and circHSH2D were identified as uniquely expressed in PD patients. Additionally, we assessed the coding potential of the predicted target genes to further elucidate the regulatory impact of circRNAs on mRNA expression. Our findings provide new insights into the post-transcriptional regulatory mechanisms involved in PD and highlight candidate stage-specific ceRNA axes that may serve as potential biomarkers or therapeutic targets.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by memory loss, cognitive decline, and neuroinflammation, primarily mediated by microglia. In this study, we investigate the role of adenylate kinase 5 (AK5) in microglial function and its association with AD-related pathology. Analysis of brain tissues from AD patients and AD model mice revealed a significant reduction in AK5 expression. In vitro knockdown of AK5 in microglial cells attenuated lipopolysaccharide-induced pro-inflammatory responses, including decreased nitric oxide and tumor necrosis factor-alpha production, while enhancing phagocytic activity. Moreover, AK5 silencing induced metabolic reprogramming, evidenced by reduced lipid droplet accumulation and adipose triglyceride lipase mRNA levels, alongside increased farnesoid X receptor mRNA expression. Genome-wide association studies further identified two AK5 single nucleotide polymorphisms (SNPs), rs59556669 and rs75224576, significantly associated with hippocampal and amygdala atrophy as well as increased AD risk. Notably, these SNPs were not in linkage disequilibrium with the apolipoprotein E (APOE) locus, suggesting that AK5 may represent an independent genetic risk factor for AD. Collectively, our findings identify AK5 as a key regulator of microglial immune and metabolic function. The presence of AK5 variants may contribute to AD susceptibility, and AK5 expression or genetic status could serve as a potential biomarker for early risk assessment. Further exploration of AK5-targeted interventions may provide new therapeutic avenues for AD prevention or treatment.

Alzheimer's disease (AD) originates from both central and peripheral pathways. The gut microbiota is a clear risk factor. In AD, microbiota imbalances drive immune system activation, disrupt protective barriers, and alter neuromodulatory signaling. Additionally, gut microbiota dysbiosis has been identified as a risk factor for AD. Recent research indicates that dysbiosis of the microbiota in AD is linked to immune activation, barrier dysfunction, and neuromodulatory signaling. Studies of AD pathology reveal that short-chain fatty acids, indole derivatives, and bile acids can have both protective and harmful effects. New strategies, such as probiotics, dietary changes, and fecal microbiota transplantation, may influence disease progression in AD. However, conflicting methods, unaccountable motives, and ethical concerns surrounding microbiome interventions pose significant hurdles. To translate findings related to the gut-brain axis into effective solutions, we need standardized multi-omics approaches, personalized therapies, and oversight from regulatory authorities. Ultimately, leveraging insights from the gut microbiome holds great promise for transforming how we diagnose, prevent, and treat AD.