Alexander disease (AxD) is a rare and severe neurodegenerative disorder caused by mutations in glial fibrillary acidic protein (GFAP). While the exact disease mechanism remains unknown, previous studies suggest that mutant GFAP influences many cellular processes, including cytoskeleton stability, mechanosensing, metabolism, and proteasome function. While most studies have primarily focused on GFAP-expressing astrocytes, GFAP is also expressed by radial glia and neural progenitor cells, prompting questions about the impact of GFAP mutations on central nervous system (CNS) development. In this study, we observed impaired differentiation of astrocytes and neurons in co-cultures of astrocytes and neurons, as well as in neural organoids, both generated from AxD patient-derived induced pluripotent stem (iPS) cells with a GFAPR239C mutation. Leveraging single-cell RNA sequencing (scRNA-seq), we identified distinct cell populations and transcriptomic differences between the mutant GFAP cultures and a corrected isogenic control. These findings were supported by results obtained with immunocytochemistry and proteomics. In co-cultures, the GFAPR239C mutation resulted in an increased abundance of immature cells, while in unguided neural organoids and cortical organoids, we observed altered lineage commitment and reduced abundance of astrocytes. Gene expression analysis revealed increased stress susceptibility, cytoskeletal abnormalities, and altered extracellular matrix and cell-cell communication patterns in the AxD cultures, which also exhibited higher cell death after stress. Overall, our results point to altered cell differentiation in AxD patient-derived iPS-cell models, opening new avenues for AxD research.
- MeSH
- Alexander Disease * genetics pathology metabolism MeSH
- Astrocytes * metabolism pathology MeSH
- Cell Differentiation * physiology MeSH
- Glial Fibrillary Acidic Protein * metabolism genetics MeSH
- Induced Pluripotent Stem Cells * metabolism MeSH
- Coculture Techniques MeSH
- Cells, Cultured MeSH
- Humans MeSH
- Mutation MeSH
- Neural Stem Cells metabolism MeSH
- Neurons metabolism pathology MeSH
- Organoids metabolism pathology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
BACKGROUND: Lipopolysaccharide (LPS)-induced inflammation of lung tissues triggers irreversible alterations in the lung parenchyma, leading to fibrosis and pulmonary dysfunction. While the molecular and cellular responses of immune and connective tissue cells in the lungs are well characterized, the specific epithelial response remains unclear due to the lack of representative cell models. Recently, we introduced human embryonic stem cell-derived expandable lung epithelial (ELEP) cells as a novel model for studying lung injury and regeneration. METHODS: ELEPs were derived from the CCTL 14 human embryonic stem cell line through activin A-mediated endoderm specification, followed by further induction toward pulmonary epithelium using FGF2 and EGF. ELEPs exhibit a high proliferation rate and express key structural and molecular markers of alveolar progenitors, such as NKX2-1. The effects of Escherichia coli LPS serotype O55:B5 on the phenotype and molecular signaling of ELEPs were analyzed using viability and migration assays, mRNA and protein levels were determined by qRT-PCR, western blotting, and immunofluorescent microscopy. RESULTS: We demonstrated that purified LPS induces features of a hybrid epithelial-to-mesenchymal transition in pluripotent stem cell-derived ELEPs, triggers the unfolded protein response, and upregulates intracellular β-catenin level through retention of E-cadherin within the endoplasmic reticulum. CONCLUSIONS: Human embryonic stem cell-derived ELEPs provide a biologically relevant, non-cancerous lung cell model to investigate molecular responses to inflammatory stimuli and address epithelial plasticity. This approach offers novel insights into the fine molecular processes underlying lung injury and repair.
- MeSH
- Cell Line MeSH
- Antigens, CD metabolism MeSH
- Endoplasmic Reticulum * metabolism drug effects MeSH
- Epithelial-Mesenchymal Transition * drug effects MeSH
- Epithelial Cells * drug effects metabolism cytology MeSH
- Cadherins * metabolism MeSH
- Humans MeSH
- Human Embryonic Stem Cells * cytology MeSH
- Lipopolysaccharides * pharmacology MeSH
- Lung * cytology MeSH
- Thyroid Nuclear Factor 1 MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Background: The intermediate filament nestin was first described in stem and progenitor cells of neural and mesenchymal origin. Additionally, it is expressed in endothelial cells during wound healing and tumorigenesis. Thus, nestin is widely regarded as a marker for proliferative endothelium. However, little is known about its role in lymphatic endothelium. Methods: Here, we analyzed the expression of nestin in the endothelium of ten human haemangiomas and ten lymphangiomas in situ by immunohistochemistry. This study aimed to investigate the expression of nestin in haemangiomas and lymphangiomas to determine its potential role as a vascular marker. Specifically, we aimed to assess whether nestin expression is restricted to proliferating endothelial cells or also present in non-proliferative blood vessels. Results: Immunohistochemically, haemangiomas were positive for CD31 but negative for D2-40. The endothelial cells within these lesions showed a homogeneous expression of nestin. In contrast, the endothelium of lymphangiomas reacted positively for D2-40 and CD31 but did not show any nestin expression. Additionally, only a few endothelial cells of capillary haemangiomas showed a Ki-67 positivity. Conclusions: The differential expression of nestin in haemangiomas and lymphangiomas indicates a specificity of nestin for the endothelium of blood vessels. The Ki-67 negativity in the majority of the endothelial cells reveals the proliferative quiescence of these cells. These findings indicate that nestin could be used as a marker to differentiate between blood and lymphatic vessels.
- Publication type
- Journal Article MeSH
Medulloblastoma, the most prevalent brain tumor among children, requires a comprehensive understanding of its cellular characteristics for effective research and treatment. In this study, we focused on DAOY, a permanent cell line of medulloblastoma, and investigated the unique properties of DAOY cells when cultured as floating multicellular aggregates called spheres, as opposed to adherent monolayers. Through our comprehensive analysis, we identified distinct characteristics associated with DAOY spheres. Our findings demonstrate that DAOY spheres express markers for both neural stem cells, such as CD133 (PROM1), and differentiated neurons, exemplified by MAP2. Additionally, our investigation revealed that spheres-derived cells exhibit heightened resistance to ionizing radiation compared to adherent cells. Consequently, our results indicate that caution is advised when interpreting experimental results obtained from adherent cell cultures and extrapolating them to in vivo situations.
- Publication type
- Journal Article MeSH
Glial cells expressing neuron-glial antigen 2 (NG2), also known as oligodendrocyte progenitor cells (OPCs), play a critical role in maintaining brain health. However, their ability to differentiate after ischemic injury is poorly understood. The aim of this study was to investigate the properties and functions of NG2 glia in the ischemic brain. Using transgenic mice, we selectively labeled NG2-expressing cells and their progeny in both healthy brain and after focal cerebral ischemia (FCI). Using single-cell RNA sequencing, we classified the labeled glial cells into five distinct subpopulations based on their gene expression patterns. Additionally, we examined the membrane properties of these cells using the patch-clamp technique. Of the identified subpopulations, three were identified as OPCs, whereas the fourth subpopulation had characteristics indicative of cells likely to develop into oligodendrocytes. The fifth subpopulation of NG2 glia showed astrocytic markers and had similarities to neural progenitor cells. Interestingly, this subpopulation was present in both healthy and post-ischemic tissue; however, its gene expression profile changed after ischemia, with increased numbers of genes related to neurogenesis. Immunohistochemical analysis confirmed the temporal expression of neurogenic genes and showed an increased presence of NG2 cells positive for Purkinje cell protein-4 at the periphery of the ischemic lesion 12 days after FCI, as well as NeuN-positive NG2 cells 28 and 60 days after injury. These results suggest the potential development of neuron-like cells arising from NG2 glia in the ischemic tissue. Our study provides insights into the plasticity of NG2 glia and their capacity for neurogenesis after stroke.
- MeSH
- Antigens metabolism MeSH
- Astrocytes metabolism MeSH
- Brain Ischemia * metabolism MeSH
- Brain metabolism MeSH
- Mice, Transgenic MeSH
- Mice MeSH
- Neural Stem Cells * metabolism MeSH
- Neuroglia metabolism MeSH
- Oligodendroglia metabolism MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Previously, a new biodegradable poly(ester urethane urea) was synthesized based on polycaprolactone-diol and fish gelatin (PU-Gel). In this work, the potential of this new material for neural tissue engineering is evaluated. Membranes with randomly oriented fibers and with aligned fibers are produced using electrospinning and characterized regarding their mechanical behavior under both dry and wet conditions. Wet samples exhibit a lower Young's modulus than dry ones and aligned membranes are stiffer and more brittle than those randomly oriented. Cyclic tensile tests are conducted and high values for recovery ratio and resilience are obtained. Both membranes exhibited a hydrophobic surface, measured by the water contact angle (WCA). Human mesenchymal stem cells from umbilical cord tissue (UC-MSCs) and human neural stem cells (NSCs) are seeded on both types of membranes, which support their adhesion and proliferation. Cells stained for the cytoskeleton and nucleus in membranes with aligned fibers display an elongated morphology following the alignment direction. As the culture time increased, higher cell viability is obtained on randomfibers for UC-MSCs while no differences are observed for NSCs. The membranes support neuronal differentiation of NSCs, as evidenced by markers for a neuronal filament protein (NF70) and for a microtubule-associated protein (MAP2).
- MeSH
- Biocompatible Materials chemistry pharmacology MeSH
- Cell Adhesion drug effects MeSH
- Cell Differentiation drug effects MeSH
- Cells, Cultured MeSH
- Humans MeSH
- Mesenchymal Stem Cells * cytology drug effects metabolism MeSH
- Neural Stem Cells * cytology drug effects metabolism MeSH
- Tensile Strength MeSH
- Polyesters * chemistry pharmacology MeSH
- Polyurethanes * chemistry pharmacology MeSH
- Cell Proliferation drug effects MeSH
- Materials Testing MeSH
- Tissue Engineering * methods MeSH
- Tissue Scaffolds chemistry MeSH
- Cell Survival drug effects MeSH
- Gelatin * chemistry MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
INTRODUCTION: Neural stem cells (NSCs) are essential for both embryonic development and adult neurogenesis, and their dysregulation causes a number of neurodevelopmental disorders, such as epilepsy and autism spectrum disorders. NSC proliferation and differentiation in the developing brain is a complex process controlled by various intrinsic and extrinsic stimuli. The mammalian target of rapamycin (mTOR) regulates proliferation and differentiation, among other cellular functions, and disruption in the mTOR pathway can lead to severe nervous system development deficits. In this study, we investigated the effect of inhibition of the mTOR pathway by rapamycin (Rapa) on NSC proliferation and differentiation. METHODS: The NSC cultures were treated with Rapa for 1, 2, 6, 24, and 48 h. The effect on cellular functions was assessed by immunofluorescence staining, western blotting, and proliferation/metabolic assays. RESULTS: mTOR inhibition suppressed NSC proliferation/metabolic activity as well as S-Phase entry by as early as 1 h of Rapa treatment and this effect persisted up to 48 h of Rapa treatment. In a separate experiment, NSCs were differentiated for 2 weeks after treatment with Rapa for 24 or 48 h. Regarding the effect on neuronal and glial differentiation (2 weeks post-treatment), this was suppressed in NSCs deficient in mTOR signaling, as evidenced by downregulated expression of NeuN, MAP2, and GFAP. We assume that the prolonged effect of mTOR inhibition is realized due to the effect on cytoskeletal proteins. DISCUSSION: Here, we demonstrate for the first time that the mTOR pathway not only regulates NSC proliferation but also plays an important role in NSC differentiation into both neuronal and glial lineages.
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- Journal Article MeSH
Human cellular models of neurodegeneration require reproducibility and longevity, which is necessary for simulating age-dependent diseases. Such systems are particularly needed for TDP-43 proteinopathies1, which involve human-specific mechanisms2-5 that cannot be directly studied in animal models. Here, to explore the emergence and consequences of TDP-43 pathologies, we generated induced pluripotent stem cell-derived, colony morphology neural stem cells (iCoMoNSCs) via manual selection of neural precursors6. Single-cell transcriptomics and comparison to independent neural stem cells7 showed that iCoMoNSCs are uniquely homogenous and self-renewing. Differentiated iCoMoNSCs formed a self-organized multicellular system consisting of synaptically connected and electrophysiologically active neurons, which matured into long-lived functional networks (which we designate iNets). Neuronal and glial maturation in iNets was similar to that of cortical organoids8. Overexpression of wild-type TDP-43 in a minority of neurons within iNets led to progressive fragmentation and aggregation of the protein, resulting in a partial loss of function and neurotoxicity. Single-cell transcriptomics revealed a novel set of misregulated RNA targets in TDP-43-overexpressing neurons and in patients with TDP-43 proteinopathies exhibiting a loss of nuclear TDP-43. The strongest misregulated target encoded the synaptic protein NPTX2, the levels of which are controlled by TDP-43 binding on its 3' untranslated region. When NPTX2 was overexpressed in iNets, it exhibited neurotoxicity, whereas correcting NPTX2 misregulation partially rescued neurons from TDP-43-induced neurodegeneration. Notably, NPTX2 was consistently misaccumulated in neurons from patients with amyotrophic lateral sclerosis and frontotemporal lobar degeneration with TDP-43 pathology. Our work directly links TDP-43 misregulation and NPTX2 accumulation, thereby revealing a TDP-43-dependent pathway of neurotoxicity.
- MeSH
- Amyotrophic Lateral Sclerosis * metabolism pathology MeSH
- C-Reactive Protein * metabolism MeSH
- DNA-Binding Proteins * deficiency metabolism MeSH
- Frontotemporal Lobar Degeneration * metabolism pathology MeSH
- Humans MeSH
- Nerve Net * metabolism pathology MeSH
- Neural Stem Cells cytology MeSH
- Neuroglia cytology MeSH
- Neurons * cytology metabolism MeSH
- Nerve Tissue Proteins * metabolism MeSH
- Reproducibility of Results MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Alpers' syndrome is an early-onset neurodegenerative disorder usually caused by biallelic pathogenic variants in the gene encoding the catalytic subunit of polymerase-gamma (POLG), which is essential for mitochondrial DNA (mtDNA) replication. The disease is progressive, incurable, and inevitably it leads to death from drug-resistant status epilepticus. The neurological features of Alpers' syndrome are intractable epilepsy and developmental regression, with no effective treatment; the underlying mechanisms are still elusive, partially due to lack of good experimental models. Here, we generated the patient derived induced pluripotent stem cells (iPSCs) from one Alpers' patient carrying the compound heterozygous mutations of A467T (c.1399G>A) and P589L (c.1766C>T), and further differentiated them into cortical organoids and neural stem cells (NSCs) for mechanistic studies of neural dysfunction in Alpers' syndrome. Patient cortical organoids exhibited a phenotype that faithfully replicated the molecular changes found in patient postmortem brain tissue, as evidenced by cortical neuronal loss and depletion of mtDNA and complex I (CI). Patient NSCs showed mitochondrial dysfunction leading to ROS overproduction and downregulation of the NADH pathway. More importantly, the NAD+ precursor nicotinamide riboside (NR) significantly ameliorated mitochondrial defects in patient brain organoids. Our findings demonstrate that the iPSC model and brain organoids are good in vitro models of Alpers' disease; this first-in-its-kind stem cell platform for Alpers' syndrome enables therapeutic exploration and has identified NR as a viable drug candidate for Alpers' disease and, potentially, other mitochondrial diseases with similar causes.
- MeSH
- DNA Polymerase gamma MeSH
- Induced Pluripotent Stem Cells * MeSH
- Humans MeSH
- DNA, Mitochondrial genetics MeSH
- Mitochondrial Diseases * MeSH
- Mutation MeSH
- NAD genetics MeSH
- Niacinamide analogs & derivatives MeSH
- Pyridinium Compounds * MeSH
- Diffuse Cerebral Sclerosis of Schilder * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Pre-mRNA splicing is a highly coordinated process. While its dysregulation has been linked to neurological deficits, our understanding of the underlying molecular and cellular mechanisms remains limited. We implicated pathogenic variants in U2AF2 and PRPF19, encoding spliceosome subunits in neurodevelopmental disorders (NDDs), by identifying 46 unrelated individuals with 23 de novo U2AF2 missense variants (including 7 recurrent variants in 30 individuals) and 6 individuals with de novo PRPF19 variants. Eight U2AF2 variants dysregulated splicing of a model substrate. Neuritogenesis was reduced in human neurons differentiated from human pluripotent stem cells carrying two U2AF2 hyper-recurrent variants. Neural loss of function (LoF) of the Drosophila orthologs U2af50 and Prp19 led to lethality, abnormal mushroom body (MB) patterning, and social deficits, which were differentially rescued by wild-type and mutant U2AF2 or PRPF19. Transcriptome profiling revealed splicing substrates or effectors (including Rbfox1, a third splicing factor), which rescued MB defects in U2af50-deficient flies. Upon reanalysis of negative clinical exomes followed by data sharing, we further identified 6 patients with NDD who carried RBFOX1 missense variants which, by in vitro testing, showed LoF. Our study implicates 3 splicing factors as NDD-causative genes and establishes a genetic network with hierarchy underlying human brain development and function.
- MeSH
- DNA Repair Enzymes genetics MeSH
- Gene Regulatory Networks MeSH
- Nuclear Proteins genetics MeSH
- Humans MeSH
- Mutation, Missense MeSH
- Neurodevelopmental Disorders * genetics MeSH
- RNA Splicing MeSH
- RNA Splicing Factors genetics MeSH
- Spliceosomes * genetics MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
