Aberrant Neuronal Connectivity and Network Activity of Neurons Derived from Patients with Idiopathic Schizophrenia
Ontology highlight
ABSTRACT: Schizophrenia (SCZ) is a psychiatric disorder with a strong genetic determinant. A major hypothesis to explain disease aetiology comprises synaptic dysfunction associated with excitatory-inhibitory imbalance of synaptic transmission, ultimately contributing to impaired network oscillation and cognitive deficits associated with the disease. Here, we studied the morphological and functional properties of a highly defined co-culture of GABAergic and glutamatergic neurons derived from induced pluripotent stem cells (iPSC) from patients with idiopathic SCZ. Our results indicate upregulation of synaptic genes and increased excitatory synapse formation on GABAergic neurons in co-cultures. In parallel, we observed decreased lengths of axon initial segments, concordant with data from postmortem brains from patients with SCZ. Patch-clamp analyses revealed differential processing of excitatory input with markedly increased spontaneous excitatory postsynaptic currents (EPSC) recorded from GABAergic SCZ neurons and decreased spontaneous EPSC from glutamatergic SCZ neurons. Likewise, we observed decreased amplitudes of calcium signals selectively in GABAergic neurons while frequency was increased in both neuronal populations. Finally, MEA recordings from neuronal networks indicate increased synchronization of network activity. In conclusion, our results suggest selective deregulation of neuronal activity and synaptic transmission in SCZ samples, providing evidence for differential signal processing in GABAergic and glutamatergic neurons as a potential base for aberrant network synchronization.
Project description:Using CRISPR/Cas9 to generate an hiPSC line with SETD1A haploinsufficiency and differentiating it into glutamatergic and GABAergic neurons, we found that SETD1A haploinsufficiency resulted in altered neuronal network activity, which was predominantly defined by increased network burst frequency, whereas unchanged global firing activity. In individual neurons, this network phenotype was reflected functionally by increased synchronized synaptic inputs and structurally by increased somatodendritic complexity in both glutamatergic and GABAergic neurons. The transcriptome profile in SETD1A haploinsufficient neurons demonstrated perturbations in gene sets associated with schizophrenia, synaptic transmission, and glutamatergic synaptic function. In addition, transcriptomic data suggested cAMP/PKA pathway might be disturbed in SETD1A haploinsufficient networks, which was further verified by pharmacological experiments.
Project description:This is a model of one presynaptic and one postsynaptic cell, as described in the article:
Gamma oscillation by synaptic inhibition in a hippocampal interneuronal network model.
Wang XJ, Buzsáki G. J Neurosci. 1996 Oct 15;16(20):6402-13. PMID:8815919;
Abstract:
Fast neuronal oscillations (gamma, 20-80 Hz) have been observed in the neocortex and hippocampus during behavioral arousal. Using computer simulations, we investigated the hypothesis that such rhythmic activity can emerge in a random network of interconnected GABAergic fast-spiking interneurons. Specific conditions for the population synchronization, on properties of single cells and the circuit, were identified. These include the following: (1) that the amplitude of spike afterhyperpolarization be above the GABAA synaptic reversal potential; (2) that the ratio between the synaptic decay time constant and the oscillation period be sufficiently large; (3) that the effects of heterogeneities be modest because of a steep frequency-current relationship of fast-spiking neurons. Furthermore, using a population coherence measure, based on coincident firings of neural pairs, it is demonstrated that large-scale network synchronization requires a critical (minimal) average number of synaptic contacts per cell, which is not sensitive to the network size. By changing the GABAA synaptic maximal conductance, synaptic decay time constant, or the mean external excitatory drive to the network, the neuronal firing frequencies were gradually and monotonically varied. By contrast, the network synchronization was found to be high only within a frequency band coinciding with the gamma (20-80 Hz) range. We conclude that the GABAA synaptic transmission provides a suitable mechanism for synchronized gamma oscillations in a sparsely connected network of fast-spiking interneurons. In turn, the interneuronal network can presumably maintain subthreshold oscillations in principal cell populations and serve to synchronize discharges of spatially distributed neurons.
The presynaptic and postsynaptic cell have identical parameters and the variables in each cell are identified by using _pre or _post as a postfix to their names. The presynaptic cell influences the postsynaptic one via the synapse (variables and parameters: I_syn, E_syn, g_syn, F, theta_syn, alpha, beta). The applied current to the presynaptic cell, I_app_pre, is set to 2 microA/cm2 for 10 ms as in figure 1C of the article. The dependence of the postsynaptic cell on directly applied current can be investigated in isolation by setting I_app_pre to 0 and altering I_app_post.
Originally created by libAntimony v1.4 (using libSBML 3.4.1)
Project description:The K+-Cl- co-transporter KCC2, encoded by the Slc12a5 gene, is a neuron-specific chloride extruder that tunes the strength and polarity of GABAA receptor-mediated transmission. Besides its canonical ion-transport function, KCC2 also regulates spinogenesis and excitatory synaptic function through interaction with a variety of molecular partners. KCC2 is enriched in the vicinity of both glutamatergic and GABAergic synapses, the activity of which in turn regulates its membrane stability and function. KCC2 interaction with submembrane actin cytoskeleton via 4.1N is known to control its anchoring in the vicinity of glutamatergic synapses on dendritic spines. However, the molecular determinants of KCC2 clustering near GABAergic synapses remain unknown. Here, we use proteomics to identify novel KCC2 interacting proteins in adult rat cortex. We identify both known and novel candidate KCC2 partners, including some involved in neuronal development and synaptic transmission. These include gephyrin, the main scaffolding molecule at GABAergic synapses. Gephyrin interaction with endogenous KCC2 was confirmed by immunoprecipitation from rat brain extracts. We show that gephyrin stabilizes plasmalemmal KCC2 and promotes its clustering, notably but not exclusively near GABAergic synapses, thereby controlling KCC2-mediated chloride extrusion. This study identifies gephyrin as a novel KCC2 anchoring molecule that regulates its membrane expression and function in cortical neurons.
Project description:Our work describes novel roles for EZH2 in the specification of cortical neurons. Previous reports established the current model of EZH2-mediated control of neuronal progenitors differentiation through the regulation of their proliferation and developmental transitions. We built on these findings and studied the role of EZH2 in post-mitotic glutamatergic neurons differentiated from embryonic stem cells, a particularly relevant cell type where the impact of its regulation has thus far remained elusive. Briefly, our key results can be summarized as follows: 1. The conditional deletion of EZH2 at the moment of cell cycle exit in neural progenitors allowed us to study the role of EZH2 selectively in post-mitotic glutamatergic neurons. 2. Time course transcriptomic and epigenomic analyses of H3K27me3 in absence of EZH2 revealed a significant dysregulation of transcriptional networks affecting synaptic plasticity, in particular long term depression. 3. These analyses also revealed potential novel roles of EZH2 in controlling the regulation between the glutamatergic signature and the GABAergic one, suggesting a mechanism entailing failure of Prdm13 repression, a histone methyltransferase with a known role in determining GABAergic neurons specification.
Project description:Our work describes novel roles for EZH2 in the specification of cortical neurons. Previous reports established the current model of EZH2-mediated control of neuronal progenitors differentiation through the regulation of their proliferation and developmental transitions. We built on these findings and studied the role of EZH2 in post-mitotic glutamatergic neurons differentiated from embryonic stem cells, a particularly relevant cell type where the impact of its regulation has thus far remained elusive. Briefly, our key results can be summarized as follows: 1. The conditional deletion of EZH2 at the moment of cell cycle exit in neural progenitors allowed us to study the role of EZH2 selectively in post-mitotic glutamatergic neurons. 2. Time course transcriptomic and epigenomic analyses of H3K27me3 in absence of EZH2 revealed a significant dysregulation of transcriptional networks affecting synaptic plasticity, in particular long term depression. 3. These analyses also revealed potential novel roles of EZH2 in controlling the regulation between the glutamatergic signature and the GABAergic one, suggesting a mechanism entailing failure of Prdm13 repression, a histone methyltransferase with a known role in determining GABAergic neurons specification.
Project description:We optimized Voltage-Seq which combines, all-optical physiology, spatial mapping, on-site classification, and RNA-transcriptomics to robustly increase the throughput of synaptic connectivity testing and targeted molecular classification of postsynaptic neurons. Single-cell RNA-sequencing was performed on spatial- and voltage-recorded neurons in the mouse PAG. Uniform Manifold Approximation and Projection (UMAP) clustered cells as excitatory or inhibitory, and further differential expression analyses highlighted putative marker genes of GABAergic neurons. These sequencing results were in agreement with in-situ hybridization (ISH) and neuronal activity recordings.
Project description:We describe the first human single-nuclei transcriptomic atlas for substantia nigra (SN), generated by sequencing ~ 17,000 nuclei from matched cortical and SN samples. We show that common genetic risk for Parkinson’s disease (PD) is associated with dopaminergic neuron (DaN)-specific gene expression including mitochondrial functioning, protein folding and ubiquitination pathways. We also identified a distinct cell-type association between PD risk and oligodendrocyte-specific expression implicating metabolic and gene expression regulation networks. Beyond PD, we find SN DaNs and GABAergic neurons to be associated with different neuropsychiatric disorders, particularly schizophrenia (SCZ) and bipolar disorder (BP). We identified distinct cortex/SN associations with SCZ genetic risk for both excitatory (synaptic functioning) and dopaminergic neurons (mitochondrial functioning and synaptic signalling). Conditional analyses shows that independent sets of loci associate distinct neuropsychiatric disorders with the same neuronal types. This atlas guides our aetiological understanding by associating SN cell-type expression profiles with specific disease risk.
Project description:Genome-wide association studies (GWAS) have identified many risk genes for neuropsychiatric disorders (NPD) such as schizophrenia (SCZ). However, functional interpretation of these GWAS findings remains challenging; a major hurdle is that polygenic risk may manifest its effect conditionally upon neural activation, i.e., context-dependent. Human induced pluripotent stem cell (hiPSC)-derived neurons are a tractable cellular model for ascertaining context-dependent polygenic effects, e.g., neural activation that may mimic the physiological effects of environmental stimuli. Here, we modelled neural activation by depolarisation using high potassium chloride (KCl) in co-cultured excitatory/inhibitory neurons of 100 hiPSC lines (28 from SCZ donors), followed by assaying single-cell multiomes (scRNA/ATAC-seq) of over 700,000 nuclei from neurons at 0 hr (unstimulated), 1 hr (early response), and 6 hr (later response) of high KCI exposure. We linked genes with open chromatin peaks for each main neural subtype (GABAergic inhibitory, NEFM+ or NEFM-excitatory neurons) and confirmed a significant correlation between peak accessibility and target gene expression. Compared to static genes/peaks, dynamic ones, specifically those activity-upregulated, were more enriched for NPD GWAS risk, with the most robust enrichment for SCZ. Based on the dynamic gene expression pattern across the three time points, we found NPD risk genes tend to be continuously upregulated (i.e., with up-up dynamics). We further analysed context-specific SCZ-associated differentially expressed genes (DEGs) using MAST for single neurons of 28 SCZ cases and 72 controls. We found that 3-5%, 4-6%, and 15-23% of genes were SCZ-associated DEGs in NEFM+ excitatory, NEFM- excitatory, and GABAergic neurons, respectively, most of which were cell activity-specific. Notably, we found that SCZ-associated DEGs in high-activity neurons were more enriched for synapse-related GO terms and NPD risk genes. Interestingly, upstream regulatory sequences of the stimulation-specific SCZ-associated DEGs were enriched for binding sites of TCF4, which is a strong GWAS risk gene and was considered the master regulator of other SCZ-related genes. Moreover, the upregulated genes in SCZ cases in the stimulated (only at 6hr) NEFM+ excitatory neurons showed strong enrichment for GO terms related to cholesterol synthesis. Single-neuron DEG analysis for 28 SCZ cases and 28 matched controls gave similar results. Our study suggests that many NPD genes may only elicit disease-relevant effects upon neuronal activation, providing novel insights into how polygenic risk factors interact with environmental stimuli for NPD.
Project description:Genome-wide association studies (GWAS) have identified many risk genes for neuropsychiatric disorders (NPD) such as schizophrenia (SCZ). However, functional interpretation of these GWAS findings remains challenging; a major hurdle is that polygenic risk may manifest its effect conditionally upon neural activation, i.e., context-dependent. Human induced pluripotent stem cell (hiPSC)-derived neurons are a tractable cellular model for ascertaining context-dependent polygenic effects, e.g., neural activation that may mimic the physiological effects of environmental stimuli. Here, we modelled neural activation by depolarisation using high potassium chloride (KCl) in co-cultured excitatory/inhibitory neurons of 100 hiPSC lines (28 from SCZ donors), followed by assaying single-cell multiomes (scRNA/ATAC-seq) of over 700,000 nuclei from neurons at 0 hr (unstimulated), 1 hr (early response), and 6 hr (later response) of high KCI exposure. We linked genes with open chromatin peaks for each main neural subtype (GABAergic inhibitory, NEFM+ or NEFM-excitatory neurons) and confirmed a significant correlation between peak accessibility and target gene expression. Compared to static genes/peaks, dynamic ones, specifically those activity-upregulated, were more enriched for NPD GWAS risk, with the most robust enrichment for SCZ. Based on the dynamic gene expression pattern across the three time points, we found NPD risk genes tend to be continuously upregulated (i.e., with up-up dynamics). We further analysed context-specific SCZ-associated differentially expressed genes (DEGs) using MAST for single neurons of 28 SCZ cases and 72 controls. We found that 3-5%, 4-6%, and 15-23% of genes were SCZ-associated DEGs in NEFM+ excitatory, NEFM- excitatory, and GABAergic neurons, respectively, most of which were cell activity-specific. Notably, we found that SCZ-associated DEGs in high-activity neurons were more enriched for synapse-related GO terms and NPD risk genes. Interestingly, upstream regulatory sequences of the stimulation-specific SCZ-associated DEGs were enriched for binding sites of TCF4, which is a strong GWAS risk gene and was considered the master regulator of other SCZ-related genes. Moreover, the upregulated genes in SCZ cases in the stimulated (only at 6hr) NEFM+ excitatory neurons showed strong enrichment for GO terms related to cholesterol synthesis. Single-neuron DEG analysis for 28 SCZ cases and 28 matched controls gave similar results. Our study suggests that many NPD genes may only elicit disease-relevant effects upon neuronal activation, providing novel insights into how polygenic risk factors interact with environmental stimuli for NPD.
Project description:Genome-wide association studies (GWAS) have identified many risk genes for neuropsychiatric disorders (NPD) such as schizophrenia (SCZ). However, functional interpretation of these GWAS findings remains challenging; a major hurdle is that polygenic risk may manifest its effect conditionally upon neural activation, i.e., context-dependent. Human induced pluripotent stem cell (hiPSC)-derived neurons are a tractable cellular model for ascertaining context-dependent polygenic effects, e.g., neural activation that may mimic the physiological effects of environmental stimuli. Here, we modelled neural activation by depolarisation using high potassium chloride (KCl) in co-cultured excitatory/inhibitory neurons of 100 hiPSC lines (28 from SCZ donors), followed by assaying single-cell multiomes (scRNA/ATAC-seq) of over 700,000 nuclei from neurons at 0 hr (unstimulated), 1 hr (early response), and 6 hr (later response) of high KCI exposure. We linked genes with open chromatin peaks for each main neural subtype (GABAergic inhibitory, NEFM+ or NEFM-excitatory neurons) and confirmed a significant correlation between peak accessibility and target gene expression. Compared to static genes/peaks, dynamic ones, specifically those activity-upregulated, were more enriched for NPD GWAS risk, with the most robust enrichment for SCZ. Based on the dynamic gene expression pattern across the three time points, we found NPD risk genes tend to be continuously upregulated (i.e., with up-up dynamics). We further analysed context-specific SCZ-associated differentially expressed genes (DEGs) using MAST for single neurons of 28 SCZ cases and 72 controls. We found that 3-5%, 4-6%, and 15-23% of genes were SCZ-associated DEGs in NEFM+ excitatory, NEFM- excitatory, and GABAergic neurons, respectively, most of which were cell activity-specific. Notably, we found that SCZ-associated DEGs in high-activity neurons were more enriched for synapse-related GO terms and NPD risk genes. Interestingly, upstream regulatory sequences of the stimulation-specific SCZ-associated DEGs were enriched for binding sites of TCF4, which is a strong GWAS risk gene and was considered the master regulator of other SCZ-related genes. Moreover, the upregulated genes in SCZ cases in the stimulated (only at 6hr) NEFM+ excitatory neurons showed strong enrichment for GO terms related to cholesterol synthesis. Single-neuron DEG analysis for 28 SCZ cases and 28 matched controls gave similar results. Our study suggests that many NPD genes may only elicit disease-relevant effects upon neuronal activation, providing novel insights into how polygenic risk factors interact with environmental stimuli for NPD.