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At least 19 recordsLinked to original sources

Optimizing NGN2 Dosage Enhances the Neuronal Enrichment of iPSC-Derived Neuronal Cultures.

Proteomic analysis of highly neuron-enriched iPSC-derived cultures can provide valuable insights into the pathogenesis of neurological disease by minimizing confounding signals from non-neuronal populations. However, single-cell iPSC clones with stable NGN2 integration at the AAVS1 locus exhibit spontaneous loss of the mCherry reporter. In addition, following NGN2 induction, cultures frequently contain proliferative progenitor cells that compromise neuronal physical integrity. Here, we show that increased DNA methylation of the EF1-α promoter is associated with mCherry silencing. Importantly, reporter silencing does not affect iNeuron derivation, as evidenced by two lines of evidence. First, single-cell proteomic analysis indicated that mCherry silencing does not drive detectable proteomic divergence in undifferentiated iPSCs. Second, bulk proteomics and immunofluorescence analyses indicated that iPSC-derived neuronal cultures, whether expressing or lacking mCherry, resemble cortical glutamatergic neurons. Instead, the primary confounding factor in iNeuron generation was suboptimal neuronal conversion, which led to cell aggregates comprised of actively proliferating progenitor cells and astrocytes as the culture developed. We found that a 4-day period of NGN2 induction substantially increases neuronal maturation and the expression of neuronal-specific markers. Moreover, transient inhibition of Notch signaling is consistent with a reduction in progenitor cells. Finally, we observed that monoallelic NGN2 integration, rather than biallelic integration, preferentially increases expression of the CNS neuronal marker GPM6A over PNS markers (PRPH, POU4F1, ILS1).

Basic Helix-Loop-Helix Proteins↗

Fetal signatures in the 3D genome of iPSC-derived neurons and their implications for disease modeling.

Induced pluripotent stem cells (iPSCs) have revolutionized neuroscience, providing an approach to generate patient-specific neurons for modeling of neurological diseases. However, it remains unclear how closely iPSC-derived neurons replicate the chromatin architecture of authentic brain neurons. Here, we uniformly processed newly generated Hi-C data from iPSC-derived neurons and neurons isolated from the human postmortem brain, together with previously published data sets comprising 228 human and 89 mouse Hi-C and snm3C-seq samples from different cell subtypes. These data were merged into 96 high-coverage contact maps used to examine chromatin features ranging from chromatin compartments and topologically associating domains (TADs) to chromatin loops, Polycomb-mediated contacts, and frequently interacting regions (FIREs). We find that iPSC-derived neurons largely retain the chromatin state of undifferentiated cells and resemble fetal rather than mature neurons. iPSC-derived neurons exhibit unusually strong compartmentalization, an enrichment of developmental genes at TAD borders, and a marked reduction of long-range repressive Polycomb-mediated contacts that typically silence early fetal programs. Although immature, iPSC-derived neurons offer advantages for modeling interactions between disease-associated SNPs and target genes, as many psychiatric disorders have neurodevelopmental origins. Integrating iPSC-derived and postmortem neuronal data sets therefore provides complementary insights into the chromatin landscape underlying disease-associated interactions. Our study offers a valuable Hi-C resource for the community and provides a detailed comparison of chromatin architecture throughout neuronal maturation, underscoring its importance for validating neuronal models and providing a robust framework for future studies.

Journal Article↗

Time-dependent effects of rapid-acting antidepressants in iPSC-derived neurons from treatment-resistant depression and healthy volunteers.

Rapid-acting antidepressants like ketamine and serotonergic psychedelics show promise for treatment-resistant depression (TRD), but the molecular mechanisms that contribute to their therapeutic effects remain unclear. Induced pluripotent stem cells (iPSCs) offer a platform to model human cortical neurons and investigate drug effects in a human-relevant system. Here, iPSCs from individuals with TRD and healthy volunteers (HVs) were differentiated into mature cortical-like neurons and treated for six and 24 h with agents being investigated as rapid-acting antidepressants, including (2 R,6 R)-hydroxynorketamine (HNK), psilocybin, lysergic acid diethylamide (LSD), and 2,5-Dimethoxy-4-iodoamphetamine (DOI). Bulk and single-cell RNA sequencing assessed global and cell-type-specific transcriptomic responses. Synaptic proteins were evaluated via Western blotting and immunocytochemistry. To validate translational relevance, transcriptomic results were compared to CSF proteomics from ketamine-treated HVs. Despite differing initial pharmacological targets, overall gene expression across all compounds was highly correlated at matched timepoints compared to vehicle control, suggesting shared downstream effects. Both glutamatergic and serotonergic drugs converged on pathways involving inflammation, mTORC1 signaling, and cellular growth. At the single-cell level, (2 R,6 R)-HNK showed distinct cell-type specific alterations: upregulation in excitatory neurons and concomitant downregulation of inhibitory neuron populations. Differentially expressed genes from (2 R,6 R)-HNK-treated neurons also overlapped with CSF proteomic signatures from ketamine-treated individuals, supporting the model's translational relevance. This study is the first to assess multiple putative rapid-acting antidepressants in parallel using an iPSC-derived neuron model. Both convergent and drug-specific changes in gene expression and pathway enrichment were observed across diverse compounds, supporting the use of human iPSC-derived neurons in antidepressant drug discovery. Clinical Trial Registry: www.clinical trials.gov, NCT02484456.

Journal Article↗

Time-Dependent Effects of Rapid-Acting Antidepressants in iPSC-Derived Neurons from Treatment-Resistant Depression and Healthy Volunteers.

UNLABELLED: Rapid-acting antidepressants like ketamine and serotonergic psychedelics show promise for treatment-resistant depression (TRD), but the molecular mechanisms that contribute to their therapeutic effects remain unclear. Induced pluripotent stem cells (iPSCs) offer a platform to model human cortical neurons and investigate drug effects in a human-relevant system. Here, iPSCs from individuals with TRD and healthy volunteers (HVs) were differentiated into mature cortical-like neurons and treated for six and 24 hours with agents being investigated as rapid-acting antidepressants, including (2R,6R)-hydroxynorketamine (HNK), psilocybin, lysergic acid diethylamide (LSD), and 2,5-Dimethoxy-4-iodoamphetamine (DOI). Bulk and single-cell RNA sequencing assessed global and cell-type-specific transcriptomic responses. Synaptic proteins were evaluated via Western blotting and immunocytochemistry. To validate translational relevance, transcriptomic results were compared to CSF proteomics from ketamine-treated HVs. Despite differing initial pharmacological targets, overall gene expression across all compounds was highly correlated at matched timepoints compared to vehicle control, suggesting shared downstream effects. Both glutamatergic and serotonergic drugs converged on pathways involving inflammation, mTORC1 signaling, and cellular growth. At the single-cell level, HNK showed distinct cell-type specific alterations: upregulation in excitatory neurons and concomitant downregulation of inhibitory neuron populations. Differentially expressed genes from HNK-treated neurons also overlapped with CSF proteomic signatures from ketamine-treated individuals, supporting the model's translational relevance. This study is the first to assess multiple putative rapid-acting antidepressants in parallel using an iPSC-derived neuron model. Both convergent and drug-specific changes in gene expression and pathway enrichment were observed across diverse compounds, supporting the use of human iPSC-derived neurons in antidepressant drug discovery. CLINICAL TRIAL REGISTRY: www.clinicaltrials.gov, NCT02484456.

Journal Article↗

Multi-omic phenotyping of iPSC-derived neurons harboring the MAPT V337M mutation reveals tau hypophosphorylation and perturbed axon morphology pathways.

Tau aggregation is a hallmark of several neurodegenerative diseases, including Alzheimer's disease and frontotemporal dementia. There are disease-causing variants of the tau-encoding gene, MAPT, and the presence of tau aggregates is highly correlated with disease progression. However, the molecular mechanisms linking pathological tau to neuronal dysfunction are not well understood. This is in part due to an incomplete understanding of the normal functions of tau in development and aging, and how the associated molecular and cellular processes change in the context of causal disease variants of tau. To address these questions in an unbiased manner, we conducted multi-omic characterization of iPSC-derived neurons harboring the MAPT V337M mutation or MAPT knockdown. RNA-seq and phosphoproteomics revealed that both V337M mutation and tau knockdown perturbed levels of transcripts and phosphorylation of proteins related to axonogenesis or axon morphology. Surprisingly, we found that neurons with V337M tau had much lower tau phosphorylation than neurons with WT tau. Functional genomics screens uncovered regulators of tau phosphorylation in neurons and found that factors involved in axonogenesis modified tau phosphorylation in both MAPT WT and MAPT V337M neurons. Intriguingly, the p38 MAPK pathway specifically modified tau phosphorylation in MAPT V337M neurons. We propose that V337M tau perturbs tau phosphorylation and axon morphology pathways that are relevant to the normal function of tau, which could contribute to previously reported cognitive changes in preclinical MAPT variant carriers.

Journal Article↗

STX1B variant-specific synaptic dysfunction is associated with network hyperexcitability in human iPSC-derived neurons.

BACKGROUND: Variants in STX1B/syntaxin-1B are linked to a spectrum of fever-associated epilepsy syndromes. While studies in murine models have provided mechanistic insights, their relevance to human disease in a heterozygous context may be limited. METHODS: We investigated two pathogenic STX1B variants using isolated single neurons and neuronal network cultures derived from patient-specific induced pluripotent stem cells. These carried either a de novo p.G226R variant, associated with severe developmental epilepsy, or an InDel variant (p.K45delinsRCMIE/p.L46M) linked to a transient familial seizure syndrome. Synaptic function and network excitability were assessed using patch-clamp and multi-electrode array recordings, alongside morphological and transcriptomic profiling. FINDINGS: G226R exhibited both gain- and loss-of-function characteristics, with increased miniature excitatory postsynaptic current frequency in networks but not in autapses, and synaptic failure during sustained high-frequency stimulation. For the InDel variant, the predicted loss-of-function phenotype based on reduced syntaxin-1B levels was not detectable at the single-cell level, likely masked by compensatory synaptic upregulation. At the network level, however, both variants were associated with neuronal hyperexcitability, characterised by more frequent and prolonged bursting activity, with a much stronger phenotype in G226R-containing networks. Transcriptomic profiling revealed a differential dysregulation of synaptic and other neuronal genes. INTERPRETATION: The divergence between morphological, electrophysiological and transcriptomic findings suggests that compensatory mechanisms may contribute to network hyperexcitability. Initially engaged to maintain homoeostasis, they may ultimately contribute to a pathological network state. The graded severity of network alterations across STX1B variants correlates with the clinical phenotypes. FUNDING: BMBF (Treat ION-01GM2210A, SNAREopathies-01EW1809A), 2023 FEBS Summer Fellowship, Fortüne programme (2610-0-0), EKFS college precise.net, Open Access Publishing Fund of University of Tübingen.

Humans↗

Antisense oligonucleotide-mediated MSH3 suppression reduces somatic CAG repeat expansion in Huntington's disease iPSC-derived striatal neurons.

Expanded CAG alleles in the huntingtin (HTT) gene that cause the neurodegenerative disorder Huntington's disease (HD) are genetically unstable and continue to expand somatically throughout life, driving HD onset and progression. MSH3, a DNA mismatch repair protein, modifies HD onset and progression by driving this somatic CAG repeat expansion process. MSH3 is relatively tolerant of loss-of-function variation in humans, making it a potential therapeutic target. Here, we show that an MSH3-targeting antisense oligonucleotide (ASO) effectively engaged with its RNA target in induced pluripotent stem cell (iPSC)-derived striatal neurons obtained from a patient with HD carrying 125 HTT CAG repeats (the 125 CAG iPSC line). ASO treatment led to a dose-dependent reduction of MSH3 and subsequent stalling of CAG repeat expansion in these striatal neurons. Bulk RNA sequencing revealed a safe profile for MSH3 reduction, even when reduced by >95%. Maximal knockdown of MSH3 also effectively slowed CAG repeat expansion in striatal neurons with an otherwise accelerated expansion rate, derived from the 125 CAG iPSC line where FAN1 was knocked out by CRISPR-Cas9 editing. Last, we created a knock-in mouse model expressing the human MSH3 gene and demonstrated effective in vivo reduction in human MSH3 after ASO treatment. Our study shows that ASO-mediated MSH3 reduction can prevent HTT CAG repeat expansion in HD 125 CAG iPSC-derived striatal neurons, highlighting the therapeutic potential of this approach.

Huntington Disease↗

A massively parallel CRISPR-based screening platform for modifiers of neuronal depolarization.

Understanding the complex interplay between gene expression and neuronal activity is crucial for unraveling the molecular mechanisms underlying cognitive function and neurological disorders. Here, we developed pooled screens using CRISPR interference (CRISPRi) and the fluorescent calcium integrator CaMPARI2 to evaluate genetic modifiers of neuronal depolarization. Using this screening method, we evaluated 1343 genes for their effect on depolarization in a human iPSC-derived neuron model, revealing potential links to neurodegenerative and neurodevelopmental disorders. These genes include known regulators of neuronal excitability, such as TARPs and ion channels, as well as genes associated with autism spectrum disorder and Alzheimer's disease not previously described to affect neuronal depolarization. This CRISPRi-based screening platform offers a versatile tool to uncover molecular mechanisms controlling neuronal function in health and disease.

Humans↗

A Massively Parallel CRISPR-Based Screening Platform for Modifiers of Neuronal Activity.

Understanding the complex interplay between gene expression and neuronal activity is crucial for unraveling the molecular mechanisms underlying cognitive function and neurological disorders. Here, we developed pooled screens for neuronal activity, using CRISPR interference (CRISPRi) and the fluorescent calcium integrator CaMPARI2. Using this screening method, we evaluated 1343 genes for their effect on excitability in human iPSC-derived neurons, revealing potential links to neurodegenerative and neurodevelopmental disorders. These genes include known regulators of neuronal excitability, such as TARPs and ion channels, as well as genes associated with autism spectrum disorder and Alzheimer's disease not previously described to affect neuronal excitability. This CRISPRi-based screening platform offers a versatile tool to uncover molecular mechanisms controlling neuronal activity in health and disease.

Journal Article↗

Mapping key mitochondrial genes in Alzheimer's disease through human tissue and iPSC derived neurons.

Alzheimer's disease (AD) is a progressive neurodegenerative condition that has become a global health challenge due to an aging world population and no available effective treatment. Mitochondrial dysfunction plays a crucial role in the development of AD due to its critical role in neuronal survival and function. However, the specific mitochondrial genes and pathways involved in AD pathogenesis remain poorly defined. In this study, we incorporated seven AD human postmortem and three AD iPSC-derived neurons (iNs) gene expression datasets to identify mitochondria-related Differentially Expressed Genes (mitoDEGs) between AD and control. The Gene Ontology (GO) analysis is conducted to investigate the AD biological mechanisms, and a random forest model is developed to assess how well the key mitoDEGs differentiate AD and control groups. Through our analysis, we identified fourteen key mitochondria related genes that show significant dysregulation in both postmortem brain tissues and iNs derived from AD patients. These genes have strong connections to oxidative stress, indicating mitochondrial dysfunction plays a crucial role in Alzheimer's disease pathology. Our study identified the key genes and pathways as promising targets for future research and therapeutic interventions, highlighting the importance of mitigating oxidative stress and restoring mitochondrial function in AD.

Humans↗

Proteome Dynamics in iPSC-Derived Human Dopaminergic Neurons.

Dopaminergic neurons participate in fundamental physiological processes and are the cell type primarily affected in Parkinson's disease. Their analysis is challenging due to the intricate nature of their function, involvement in diverse neurological processes, and heterogeneity and localization in deep brain regions. Consequently, most of the research on the protein dynamics of dopaminergic neurons has been performed in animal cells ex vivo. Here we use iPSC-derived human mid-brain-specific dopaminergic neurons to study general features of their proteome biology and provide datasets for protein turnover and dynamics, including a human axonal translatome. We cover the proteome to a depth of 9409 proteins and use dynamic SILAC to measure the half-life of more than 4300 proteins. We report uniform turnover rates of conserved cytosolic protein complexes such as the proteasome and map the variable rates of turnover of the respiratory chain complexes in these cells. We use differential dynamic SILAC labeling in combination with microfluidic devices to analyze local protein synthesis and transport between axons and soma. We report 105 potentially novel axonal markers and detect translocation of 269 proteins between axons and the soma in the time frame of our analysis (120 h). Importantly, we provide evidence for local synthesis of 154 proteins in the axon and their retrograde transport to the soma, among them several proteins involved in RNA editing such as ADAR1 and the RNA helicase DHX30, involved in the assembly of mitochondrial ribosomes. Our study provides a workflow and resource for the future applications of quantitative proteomics in iPSC-derived human neurons.

Humans↗

Integrative multi-omics identifies DOC2A as a novel pharmacological target for bipolar disorder.

BACKGROUND: Current bipolar disorder (BD) therapies suffer from limited efficacy and adverse effects, necessitating mechanistically grounded targets. METHODS: We integrated BD genome-wide association study data (158,036 cases; 2,796,499 controls) with brain proteomics (ROSMAP and Banner dorsolateral prefrontal cortex, n&#xa0;=&#xa0;376 and 152) to perform proteome-wide association studies (PWAS). Bayesian colocalization and summary-data-based Mendelian randomization (SMR) prioritized causal genes. Cell-type-specific transcriptomics validated dysregulation in iPSC-derived neurons, astrocytes, and postmortem hippocampus/prefrontal cortex. Weighted gene co-expression networks (WGCNAs), functional enrichment, and molecular docking assessed functional pathways and druggability. RESULTS: PWAS identified eight BD-associated genes (false discovery rate&#xa0;<&#xa0;0.05), with DOC2A emerging as the top candidate. Colocalization (H4&#xa0;>&#xa0;0.8) and SMR supported a causal association of DOC2A with BD, with no pleiotropy (heterogeneity in dependent instruments P&#xa0;>&#xa0;0.01); DOC2A expression decreased in BD across neurons (P&#xa0;=&#xa0;4.26&#xa0;&#xd7;&#xa0;10-2), astrocytes (P&#xa0;=&#xa0;2.09&#xa0;&#xd7;&#xa0;10-2), hippocampus (P&#xa0;=&#xa0;9.80&#xa0;&#xd7;&#xa0;10-3, t&#xa0;=&#xa0;-2.738), and prefrontal cortex (P&#xa0;=&#xa0;1.44&#xa0;&#xd7;&#xa0;10-2, t&#xa0;=&#xa0;-2.580); WGCNA positioned DOC2A as a key regulator (module membership/gene significance P&#xa0;<&#xa0;0.05) of co-expression networks enriched for BD-associated processes including neurotransmitter secretion and postsynaptic actin cytoskeleton organization (P&#xa0;<&#xa0;0.05); molecular docking revealed favorable-affinity binding (&#x394;G&#xa0;<&#xa0;-4&#xa0;kcal/mol) between DOC2A and BD-related drugs and neuroprotective compounds. CONCLUSIONS: Our convergent multi-omics framework highlights DOC2A dysregulation as a key contributor to synaptic dysfunction in BD and nominates it as a promising therapeutic target. The demonstrated interaction with existing neuroactive compounds provides immediate translational avenues.

Bipolar Disorder↗

A novel iPSC model of Bryant-Li-Bhoj neurodevelopmental/neurodegenerative syndrome demonstrates the role of histone H3.3 in chromatin dynamics, neuronal differentiation, and maturation.

BACKGROUND: Bryant-Li-Bhoj neurodevelopmental syndrome (BLBS) is neurogenetic disorder caused by variants in H3-3A and H3-3B, the two genes that encode histone H3.3. Ninety-nine percent of individuals with BLBS show developmental delay/intellectual disability, but the mechanism by which variants in H3.3 result in these phenotypes is not yet understood, limiting the therapeutic interventions available to individuals living with BLBS. METHODS: Here, we investigate how one BLBS-causative variant, H3-3B p.Leu48Arg (L48R), affects neurodevelopment using an induced pluripotent stem cell model differentiated to 2D neural progenitor cells (NPCs), 2D forebrain neurons (FBNs), and 3D dorsal forebrain organoids (DFBOs). We employ a multi-omic approach in the 2D models to quantify the resulting changes in gene expression and chromatin accessibility. We used immunofluorescence (IF) staining to define the identities of cells in the 3D DFBOs and whole-cell patch clamp to investigate the electrophysiological properties of neurons in DFBOs. RESULTS: In the 2D systems, we found dysregulated gene expression and chromatin accessibility affecting neuronal fate, adhesion, neurotransmission, and excitatory/inhibitory balance. Immunofluorescence of DFBOs corroborated altered proportions of radial glia and mature neuronal populations. Patch clamp recordings revealed decreased electrical activity in neurons from L48R DFBOs compared to control DFBOs. CONCLUSIONS: These data provide the first mechanistic insights into the pathogenesis of BLBS from a human-derived model of neurodevelopment, which suggest that H3.3 L48R increases H3-3B expression, resulting in the hyper-deposition of H3.3 into the nucleosome, which underlies changes in gene expression and chromatin accessibility. Functionally, this causes dysregulation of cell adhesion, neurotransmission, and the balance between excitatory and inhibitory signaling. These results are a crucial step towards preclinical development and testing of targeted therapies for this and related disorders.

Histones↗

Telomeric DNA damage response mediates neurotoxicity of A&#x3b2;42 oligomers in Alzheimer's disease.

Ageing is the major risk factor for Alzheimer's disease (AD), the most common neurodegenerative disorder. DNA damage is a hallmark of ageing, particularly when occurring at telomeres, genomic regions vulnerable to oxidative damage and often challenging for the cell to repair. Here, we show that brains of 3xTg-AD mice, an established AD model characterized by amyloid-&#x3b2; (A&#x3b2;)-induced pathology, exhibit increased activation of DNA damage response (DDR) pathways at telomeres. Exposure of mouse primary hippocampal neurons to 42-residue A&#x3b2; (A&#x3b2;42) oligomers, a significant pathogenetic contributor to AD, triggers telomeric DDR by increasing the levels of reactive oxygen species caused by calcium imbalance. Antisense oligonucleotides targeting non-coding RNAs generated at damaged telomeres in vivo (in 3xTg-AD mice) and in vitro reduce neurotoxicity in iPSC-derived human cortical neurons and mouse primary neurons while inhibiting A&#x3b2;42-induced telomeric DDR, and restore transcriptional pathways altered by A&#x3b2; and found dysregulated in AD patients. These results unveil an unexpected&#xa0;role of telomeric DNA damage responses in Alzheimer's disease pathogenesis, and suggest a novel target for the development of RNA-based therapies.

Alzheimer Disease↗

Evaluation of a biomarker for amyotrophic lateral sclerosis derived from a hypomethylated DNA signature of human motor neurons.

Amyotrophic lateral sclerosis (ALS) lacks a specific biomarker, but is defined by relatively selective toxicity to motor neurons (MN). As others have highlighted, this offers an opportunity to develop a sensitive and specific biomarker based on detection of DNA released from dying MN within accessible biofluids. Here we have performed whole genome bisulfite sequencing (WGBS) of iPSC-derived MN from neurologically normal individuals. By comparing MN methylation with an atlas of tissue methylation we have derived a MN-specific signature of hypomethylated genomic regions, which accords with genes important for MN function. Through simulation we have optimised the selection of regions for biomarker detection in plasma and CSF cell-free DNA (cfDNA). However, we show that MN-derived DNA is not detectable via WGBS in plasma cfDNA. In support of our experimental finding, we show theoretically that the relative sparsity of lower MN sets a limit on the proportion of plasma cfDNA derived from MN which is below the threshold for detection via WGBS. Our findings are important for the ongoing development of ALS biomarkers. The MN-specific hypomethylated genomic regions we have derived could be usefully combined with more sensitive detection methods and perhaps with study of CSF instead of plasma. Indeed we demonstrate that neuronal-derived DNA is detectable in CSF. Our work is relevant for all diseases featuring death of rare cell-types.

Humans↗

Base editing rescues a hereditary motor neuron disease in mouse and patient-derived iPSC organoid models.

In hereditary motor neuron diseases (MNDs), including forms of amyotrophic lateral sclerosis (ALS) caused by single-nucleotide variants, effective therapeutic strategies need to address both gain- and loss-of-function mechanisms. Genome editing-based gene therapy represents a promising approach for simultaneously targeting these mechanisms. To establish proof-of-concept for base editing in a hereditary MND, we targeted the P285L variant in the TRK-fused gene (TFG), which causes hereditary motor and sensory neuropathy with proximal dominant involvement (HMSN-P), a disorder that shares clinical and histopathological features with ALS. We identified the optimal adenine base editor by comparing candidate editors in HMSN-P patient-derived induced pluripotent stem cells (iPSCs). We then generated a transgenic mouse model expressing human TFG P285L and evaluated the selected editor by subpial delivery of adeno-associated virus (AAV) vectors to the spinal cord. AAV-mediated base editing prolonged survival, preserved motor neurons, and attenuated axon loss in ventral nerve roots. Treatment with the selected base editing vector reduced TFG aggregation and suppressed neuronal death in HMSN-P iPSC-derived neuromuscular organoids. Collectively, these findings support the therapeutic potential of base editing for hereditary MNDs.

AAV↗

Cholesterol dysregulation in APOE4 astrocytes promotes &#x3b1;-synuclein pathology in miBrains.

The pathological hallmarks of neurodegeneration are the aberrant post-translational modification and aggregation of proteins. Genetic factors, like APOE4, increase the prevalence and severity of tau, amyloid, and &#x3b1;-synuclein pathologies. However, the human brain is largely inaccessible during this process, limiting mechanistic understanding. Here, we developed an iPSC-based 3D model that integrates neurons, glia, myelin, and cerebrovascular cells into a human brain-like tissue ("miBrain"). Single-nucleus RNA sequencing of miBrains confirmed the presence of diverse cell populations and revealed transcriptional responses to &#x3b1;-synuclein pathology. Like the human brain, pathogenic &#x3b1;-synuclein is increased in APOE4/4 miBrains. Combinatorial experiments revealed that endolysosomal dysfunction caused by cholesterol accumulation in APOE4/4 astrocytes impairs the degradation of soluble &#x3b1;-synuclein leading to a pathogenic transformation that seeds &#x3b1;-synuclein inclusions in neurons. Collectively, this study establishes a robust model for investigating protein inclusions in human iPSC-derived brain tissue and highlights the role of astrocytes and cholesterol in APOE4-mediated pathologies.

alpha-Synuclein↗

ARID5A RNA-binding coordinates microglial defense and ferroptosis in iPSC-derived models.

RNA-binding proteins (RBPs) are key regulators of gene expression that shape cellular function in health and disease. However, the roles of RBPs in immune cells within the central nervous system (CNS) remain poorly understood. Here, we identify ARID5A as an RBP highly expressed in microglia and uncover its RNA-mediated regulatory functions using integrated multi-omics analyses of its RNA, DNA, and protein interactions. ARID5A regulates the splicing and translation of its RNA targets, many of which are integral to lysosomal, immune, and iron metabolism pathways. We confirm the functional relevance of this ARID5A-dependent RNA regulatory network by demonstrating that ARID5A modulates lysosomal activity, cytokine secretion, iron accumulation, and ferroptosis in iPSC-derived microglia. We further demonstrate that knockdown of microglial ARID5A reduces neuronal ferroptosis in co-cultures, underscoring the interconnected nature of these pathways. Moreover, in microglia harboring the TREM2-T66M mutation, ARID5A depletion restores dysregulated lysosomal and metabolic functions. Our results highlight the importance of protein-RNA interactions in regulating microglial cell biology.

Microglia↗