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Found: 5 465
Page 157 of 547-
Synaptic ribbons in pinealocytes of castrated rats and rats treated with estradiol.
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Studies of the respiration of synaptosomes.
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Transcriptomic Landscape and Functional Characterization of Induced Pluripotent Stem Cell-Derived Cerebral Organoids in Schizophrenia.
IMPORTANCE: Three-dimensional cerebral organoids generated from patient-derived induced pluripotent stem cells (iPSCs) may be used to interrogate cellular-molecular underpinnings of schizophrenia. OBJECTIVE: To determine transcriptomic profiles and functional characteristics of cerebral organoids from patients with schizophrenia using gene expression studies, complemented with investigations of mitochondrial function through measurement of real-time oxygen consumption rate, and functional studies of neuronal firing with microelectrode arrays. DESIGN, SETTING, AND PARTICIPANTS: This case-control study was conducted at Massachusetts General Hospital between 2017 and 2019. Transcriptomic profiling of iPSC-derived cerebral organoids from 8 patients with schizophrenia and 8 healthy control individuals was undertaken to identify cellular pathways that are aberrant in schizophrenia. Induced pluripotent stem cells and cerebral organoids were generated from patients who had been diagnosed as having schizophrenia and from heathy control individuals. MAIN OUTCOMES AND MEASURES: Transcriptomic analysis of iPSC-derived cerebral organoids from patients with schizophrenia show differences in expression of genes involved in synaptic biology and neurodevelopment and are enriched for genes implicated in schizophrenia genome-wide association studies (GWAS). RESULTS: The study included iPSC lines generated from 11 male and 5 female white participants, with a mean age of 38.8 years. RNA sequencing data from iPSC-derived cerebral organoids in schizophrenia showed differential expression of genes involved in synapses, in nervous system development, and in antigen processing. The differentially expressed genes were enriched for genes implicated in schizophrenia, with 23% of GWAS genes showing differential expression in schizophrenia and control organoids: 10 GWAS genes were upregulated in schizophrenia organoids while 15 GWAS genes were downregulated. Analysis of the gene expression profiles suggested dysregulation of genes involved in mitochondrial function and those involved in modulation of excitatory and inhibitory pathways. Studies of mitochondrial respiration showed lower basal consumption rate, adenosine triphosphate production, proton leak, and nonmitochondrial oxygen consumption in schizophrenia cerebral organoids, without any differences in the extracellular acidification rate. Microelectrode array studies of cerebral organoids showed no differences in baseline electrical activity in schizophrenia but revealed a diminished response to stimulation and depolarization. CONCLUSIONS AND RELEVANCE: Investigations of patient-derived cerebral organoids in schizophrenia revealed gene expression patterns suggesting dysregulation of a number of pathways in schizophrenia, delineated differences in mitochondrial function, and showed deficits in response to stimulation and depolarization in schizophrenia.
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Genetic models of Cushing's disease : From cells, in vivo transgenic models to human pituitary organoids.
Cushing's disease (CD) is caused by pituitary tumors that overproduce adrenocorticotropic hormone (ACTH); however, effective medical treatments remain limited, significantly impairing patients' quality of life and prognosis. Despite extensive molecular analyses, the pathogenesis of CD remains unclear. Although previous molecular studies have relied heavily on rodent-derived cells and rodent transgenic models, significant species differences exist in the tumorigenesis of CD between humans and rodents. To date, an established human CD cell model is lacking, as human CD cells are limited in availability and sustainability over time. Additionally, the gene modifications used in transgenic models do not necessarily reflect the causative genes in CD. CD tumors exhibit wide phenotypic heterogeneity, which further complicates the development of an ideal genetic model. In this review, we provide an analysis of 11 genetic models used to study CD, outlining their historical development, strengths, and limitations. Additionally, we discuss the ongoing development of human induced pluripotent stem cell (iPSC)-derived pituitary organoids and further describe various models of pituitary organoids as an emerging novel approach to studying CD. By comparing all these models, we highlight the necessity of advancing genetic models to improve our understanding and treatment of CD.
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Protocol for generating human assembloids to investigate thalamocortical and corticothalamic synaptic transmission and plasticity.
Human induced pluripotent stem cells (hiPSCs) can be used to generate assembloids that recreate thalamocortical circuitry displaying short-term and long-term synaptic plasticity. Here, we describe a protocol for differentiating hiPSCs into thalamic and cortical organoids and then fusing them to generate thalamocortical assembloids. We detail the steps for using whole-cell patch-clamp electrophysiology to investigate the properties of synaptic transmission and synaptic plasticity in this model system. For complete details on the use and execution of this protocol, please refer to Patton et al.1.
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Ethanol exposure impaired mitotic division in apical radial glial cells and disrupted early cortical development in human forebrain organoids: Implications for ethanol-induced microcephaly.
Maternal alcohol exposure can severely disrupt the differentiation of neural stem/progenitor cells, leading to a reduced number of neurons and decreased volume and thickness of the cortical layers, a hallmark feature commonly associated with microcephaly. Recent studies from our laboratory have demonstrated that ethanol exposure interfered with the formation of radial glial processes and impaired the generation and migration of outer radial glial cells in human forebrain organoids. However, the precise mechanisms by which ethanol affects the production of outer radial glial cells remain unclear. In this study, human forebrain organoids were used to investigate the effects of ethanol exposure on the mitotic divisions of radial glial cells and cortical development. Our findings revealed that ethanol exposure significantly reduced mitotic cell division in apical radial glial cells. Exposure to ethanol also significantly decreased symmetric cell division while increasing asymmetrical cell division in these cells. Additionally, ethanol exposure reduced the number of outer radial glial cells in forebrain organoids, suggesting that ethanol exposure impaired the production of outer radial glial cells by disrupting the mitotic division of apical radial glial cells. Our findings also revealed that ethanol-induced disruptions in mitotic cell division in apical radial cells and the subsequent reduction in outer radial glial cells contributed to the reduced thickness of the developing cortical wall and resulted in smaller forebrain organoids. This study significantly advances our understanding of the cellular mechanisms underlying ethanol-induced microcephaly and provides potential avenues for developing novel interventions to prevent or mitigate the neurodevelopmental deficits associated with prenatal alcohol exposure, including ethanol-induced microcephaly.
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SARS-CoV-2 Infection Induces Dopaminergic Neuronal Loss in Midbrain Organoids.
COVID-19 is mainly associated with respiratory symptoms, although several reports show that SARS-CoV-2 affects the nervous system. We evaluated the effects of SARS-CoV-2 infection on human derived midbrain organoids by exposing them to the virus (multiplicity of infection 0.05, 16-h exposure) and analyzing cellular and molecular changes at 4 and 28 days post-infection using immunofluorescence microscopy and RNA sequencing. SARS-CoV-2 nucleocapsid protein preferentially colocalized with tyrosine hydroxylase-positive (TH+) dopaminergic neurons, inducing neurite fragmentation and cellular stress. Transcriptomic analysis revealed dysregulation of pathways related to cell stress and death, DNA damage response, neurodevelopment, and neuronal survival at both timepoints. Persistent alterations in vesicle trafficking, Notch signaling, and mitochondrial function were observed at 28 days post-infection. Analysis of non-coding RNA expression highlighted dysregulated genomic regions associated with viral replication and neurite growth. These findings demonstrate selective vulnerability of dopaminergic neurons to SARS-CoV-2 infection with persistent molecular alterations, providing mechanistic insights into potential neurological consequences of COVID-19.
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Exploring the Expanded Role of Astrocytes in Primate Brain Evolution via Changes in Gene Expression.
BACKGROUND: Astrocytes are a subtype of glial cells, which are non-neuronal cells that do not produce action potentials. Rather, astrocytes are involved in various functions vital to a functioning brain including nutrient supply to neuronal cells, blood-brain barrier maintenance, regulation of synaptic transmission, and repair following CNS injury. SUMMARY: While astrocytes have been examined extensively in rodents, it is now clear that there is a large amount of astrocyte heterogeneity and increased complexity in mammals and primates. Astrocytes have expanded in the human lineage with respect to density, soma volume, and the ratio of astrocytes to total glial cells. The human prefrontal cortex also possesses an overall increased glia:neuron ratio relative to other primates, coinciding with allometric expectations based on overall brain size. KEY MESSAGES: What are the underlying changes in astrocytes in primate evolution? For this review, we will focus on the evolution of gene expression and gene regulation in astrocytes as a read out of the phenotypic changes seen in cellular morphology. This is an exciting time to understand this cell type in a more dynamic and complex way with new technologies such as induced pluripotent stem cells and single-cell RNA sequencing. Furthermore, understanding the evolution of astrocytes across primates will help explain their role in neurological disease as alterations in astrocyte function are implicated in many neurodegenerative states such as Alzheimer's disease and Parkinson's disease.
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Adducins regulate morphology and fate of neural progenitors during neocortical neurogenesis.
The evolutionary expansion of the mammalian neocortex is driven by increased proliferative capacity of neural progenitor cells. However, the molecular machinery controlling the proliferation of apical and basal progenitors during neocortical development remains poorly understood. Here, we show that the three actin-associated morpho-regulatory adducins (ADD1-3) underlie the abundance of basal progenitors in the developing ferret and mouse neocortex in vivo and in human cortical organoids. Overexpression of adducins in the embryonic mouse neocortex enhances the number of basal progenitor protrusions, resulting in increased proliferative capacity and neuronal output. Conversely, knockout of ADD1 in human cortical organoids, which also leads to downregulation of other adducins, results in reduced progenitor abundance and aberrant neurogenesis. Hence, our findings establish adducins as critical regulators of neural progenitor proliferation and fate, key cellular features underlying the progression of mammalian neurogenesis.
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Modeling Friedreich's ataxia with Bergmann glia-enriched human cerebellar organoids.
The human cerebellum is implicated in various neurological and psychiatric diseases, but its complex development and cellular diversity have posed challenges for in vitro modeling. Here, we report the generation of human induced pluripotent stem cell (iPSC)-derived cerebellar organoids (hCBOs) that are characterized by induction of rhombomere 1 (R1) cellular identity and followed by derivation of typical neuronal and glial cell types of the cerebellum. In contrast to forebrain organoids with multiple neural rosettes and inside-out neuronal migration, hCBOs develop a germinal zone on the outermost surface of the organoids with outside-in neuronal migration. These hCBOs produce various neuronal cell types resembling granule neurons, Purkinje cells, Golgi neurons, and deep cerebellar nuclei. By using a glial induction strategy, we generate Bergmann glial cells (BGCs) that serve as scaffolds for migratory granule cells and enhance electrophysiological activity of the hCBOs. Furthermore, by generating hCBOs from patients with Friedreich's ataxia (FRDA), we reveal disease-specific phenotypes that can be reversed by histone deacetylase (HDAC) inhibitors and gene editing by CRISPR-Cas9. Taken together, our advanced hCBO model provides new opportunities to investigate the mechanisms of cerebellar ontogenesis and utilize patient-derived iPSCs for translational research.