Error-prone protein synthesis recapitulates early symptoms of Alzheimer disease in aging mice
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE193459 | GEO | 2022/09/19
REPOSITORIES: GEO
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Project description:Network hyperexcitability is manifested as frequent ictal discharges, often caused by unbalanced neurotransmission. We assessed synaptic changes in the hyperexcitable visual cortex of tetanus neurotoxin-injected mice (TeNT). A proteomics analysis of synaptic content revealed Carboxypeptidase E (CPE) up-regulation following TeNT injection. To quantify CPE effect on vesicle clustering, we used an ultrastructural measure of synaptic activity to investigate functional differences at excitatory and inhibitory synapses. We found homeostatic changes in hyperexcitable networks expressed as an early onset lengthening of active zones at inhibitory synapses followed by spatial reorganization at excitatory synapses. Moreover, inhibition of CPE decreases ictal discharges in vivo. This study reveals a complex landscape of homeostatic changes affecting the synaptic release machinery , differentially at inhibitory and excitatory terminals. We propose a novel homeostatic presynaptic mechanism which may impact release timing rather than synaptic strength.
2021-09-09 | PXD022270 | Pride
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.
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2011-01-24 | BIOMD0000000302 | BioModels
Project description:Studies have shown that HIV-infected patients develop neurocognitive disorders characterized by neuronal dysfunction. The lack of productive infection of neurons by HIV suggests that viral and cellular proteins, with neurotoxic activities, released from HIV-1-infected target cells can cause this neuronal deregulation. The viral protein R (Vpr), a protein encoded by HIV-1, has been shown to alter the expression of various important cytokines and inflammatory proteins in infected and uninfected cells; however the mechanisms involved remain unclear. Using a human neuronal cell line, we found that Vpr can be taken up by neurons causing: (i) deregulation of calcium homeostasis, (ii) endoplasmic reticulum-calcium release, (iii) activation of the oxidative stress pathway, (iv) mitochondrial dysfunction and v- synaptic retraction. In search for the cellular factors involved, we performed microRNAs and gene array assays using human neurons (primary cultures or cell line, SH-SY5Y) that we treated with recombinant Vpr proteins. Interestingly, Vpr deregulates the levels of several microRNAs (e.g. miR-34a) and their target genes (e.g. CREB), which could lead to neuronal dysfunctions. Therefore, we conclude that Vpr plays a major role in neuronal dysfunction through deregulating microRNAs and their target genes, a phenomenon that could lead to the development of neurocognitive disorders. Using primary cultures and neuronal cell lines, we examined the impact of a viral protein (HIV-1 Vpr) on the expression of miRNAs and mRNAs.
2013-02-12 | E-GEOD-44266 | biostudies-arrayexpress
Project description:Evidence suggests that impaired synaptic and firing homeostasis represents a driving force of early Alzheimer’s disease (AD) progression. Here, we examine synaptic and sleep homeostasis in a Drosophila model by overexpressing human amyloid precursor protein (APP), whose duplication and mutations cause familial early-onset AD. We find that APP overexpression induces synaptic hyperexcitability. RNA-seq data indicate exaggerated expression of Ca2+ related signaling genes in APP mutants, including genes encoding Dmca1D, calcineurin (CaN) complex, and IP3R, but not in hyperexcitable mutants caused by TrpA1 or Shal/Kv4. We further demonstrate that increased CaN activity triggers transcriptional activation of Itpr (IP3R) through activating nuclear factor of activated T cells (NFAT). Strikingly, APP overexpression causes defects in both synaptic downscaling and sleep deprivation induced sleep rebound, and both defects could be restored by inhibiting IP3R. Our findings uncover IP3R as a shared signaling molecular in synaptic downscaling and sleep homeostasis, and its dysregulation may lead to synaptic hyperexcitability and AD progression at early stage.
2022-02-18 | GSE196770 | GEO
Project description:Studies have shown that HIV-infected patients develop neurocognitive disorders characterized by neuronal dysfunction. The lack of productive infection of neurons by HIV suggests that viral and cellular proteins, with neurotoxic activities, released from HIV-1-infected target cells can cause this neuronal deregulation. The viral protein R (Vpr), a protein encoded by HIV-1, has been shown to alter the expression of various important cytokines and inflammatory proteins in infected and uninfected cells; however the mechanisms involved remain unclear. Using a human neuronal cell line, we found that Vpr can be taken up by neurons causing: (i) deregulation of calcium homeostasis, (ii) endoplasmic reticulum-calcium release, (iii) activation of the oxidative stress pathway, (iv) mitochondrial dysfunction and v- synaptic retraction. In search for the cellular factors involved, we performed microRNAs and gene array assays using human neurons (primary cultures or cell line, SH-SY5Y) that we treated with recombinant Vpr proteins. Interestingly, Vpr deregulates the levels of several microRNAs (e.g. miR-34a) and their target genes (e.g. CREB), which could lead to neuronal dysfunctions. Therefore, we conclude that Vpr plays a major role in neuronal dysfunction through deregulating microRNAs and their target genes, a phenomenon that could lead to the development of neurocognitive disorders. Human fetal neurons were chosen to examine the impact of HIV-1 Vpr protein on gene expression
2012-12-07 | E-GEOD-42424 | biostudies-arrayexpress
Project description:Studies have shown that HIV-infected patients develop neurocognitive disorders characterized by neuronal dysfunction. The lack of productive infection of neurons by HIV suggests that viral and cellular proteins, with neurotoxic activities, released from HIV-1-infected target cells can cause this neuronal deregulation. The viral protein R (Vpr), a protein encoded by HIV-1, has been shown to alter the expression of various important cytokines and inflammatory proteins in infected and uninfected cells; however the mechanisms involved remain unclear. Using a human neuronal cell line, we found that Vpr can be taken up by neurons causing: (i) deregulation of calcium homeostasis, (ii) endoplasmic reticulum-calcium release, (iii) activation of the oxidative stress pathway, (iv) mitochondrial dysfunction and v- synaptic retraction. In search for the cellular factors involved, we performed microRNAs and gene array assays using human neurons (primary cultures or cell line, SH-SY5Y) that we treated with recombinant Vpr proteins. Interestingly, Vpr deregulates the levels of several microRNAs (e.g. miR-34a) and their target genes (e.g. CREB), which could lead to neuronal dysfunctions. Therefore, we conclude that Vpr plays a major role in neuronal dysfunction through deregulating microRNAs and their target genes, a phenomenon that could lead to the development of neurocognitive disorders. Human neurons SH-SY5Y were chosen to examine the impact of HIV-1 Vpr protein on gene expression
2013-01-17 | E-GEOD-43535 | biostudies-arrayexpress
Project description:Sepsis-associated encephalopathy (SAE) is a major and frequent complication in patients with sepsis resulting in delirium and premature death. Sepsis survivors commonly suffer from long-term cognitive impairment causing immense burden on patients, caregivers, and economic health systems. Underlying pathophysiology of SAE related cognitive deficits is largely unresolved, Thus treatment options are missing. We report that experimental polymicrobial sepsis in mice induces synaptic pathology in the central nervous system underlying defective long-term potentiation and cognitive dysfunction. Analysis of differentially expressed genes revealed severely affected downregulation of genes related to neuronal and synaptic signaling in the brain, e.g. of the activity-regulated cytoskeleton-associated protein (Arc ), of the transcription-regulatory EGR family, and of the dual-specificity phosphatase 6 (Dusp6). On the protein level, ARC expression and mitogen-activated protein (MAP) kinase signaling in the brain was disturbed during SAE. For targeted rescue of dysregulated synaptic signaling and plasticity, we overexpressed ARC in the hippocampus by bilateral in-vivo stereotactic microinjection of an adeno-associated virus containing a neuron-specific plasmid of the Arc transgene. Hereby, defective synaptic plasticity and signaling in the hippocampus were restored and memory function improved. Accordingly, synaptic plasticity, neuronal spine pathology, and memory dysfunction also improved when post-septic mice were subjected to enriched environment demonstrating the potential for activity-induced recovery of long-term cognitive dysfunction. Together, we identified synaptic pathology of neurocognitive dysfunction after severe systemic infection and provide a proof-of-concept approach to interfere with SAE pathomechanisms leading to cognitive improvement.
2021-02-27 | GSE167610 | GEO
Project description:Angelman syndrome (AS) is a neurogenetic developmental disorder that results from the loss of E3 ubiquitin ligase UBE3A due to mutations in or deletions of the maternally inherited UBE3A allele. While mouse models of AS have implicated abnormal synaptic signaling and plasticity underlying behavioral dysfunction, how the loss of UBE3A contributes to hyperactivity of neuronal networks seen in AS patients remains unclear. Here, by utilizing human induced neurons and 3D cortical organoids derived from AS patient iPSCs and CRISPR-Cas9 mediated UBE3A KO hESCs, we uncovered a novel role of UBE3A in suppressing neuronal hyperexcitability via ubiquitin-mediated degradation of BK channels. More importantly, augmented BK channel activity in neurons manifested as increased intrinsic excitability of neurons and network level bursting and synchronization, which can be pharmacologically normalized by BK antagonists. Our study has illustrated the utility of modeling neurological diseases with human neural cells, and our results have provided new insights into underlying pathophysiological mechanisms and potential therapeutic strategy in Angelman syndrome.
2020-08-18 | GSE120225 | GEO
Project description:Several proteins have been linked to neurodegenerative disorders (NDDs), but their molecular function is not completely understood. Here, we used quantitative interaction proteomics to identify binding partners of Amyloid beta precursor protein (APP) and Presenilin-1 (PSEN1) for Alzheimer’s disease (AD), Huntingtin (HTT) for Huntington’s disease, Parkin-2 (PARK-2) for Parkinson’s disease and Ataxin-1 (ATXN-1) for spinocerebellar ataxia type 1. Our network reveals common signatures of protein degradation and misfolding and recapitulates known biology. Toxicity modifier screens and comparison to genome-wide association studies show that interaction partners are significantly linked to disease phenotypes in vivo. Direct comparison of wild-type proteins and disease-associated variants identified binders involved in pathogenesis, highlighting the value of differential interactome mapping. Finally, we show that the mitochondrial protein LRPPRC interacts preferentially with an early onset AD variant of APP. This interaction appears to induce mitochondrial dysfunction, which is an early phenotype of AD.
2015-09-22 | PXD001942 | Pride
Project description:Neurodevelopmental disorders (NDDs) are genetically heterogeneous, yet often share certain features such as intellectual disability or motor incoordination. MeCP2 dysfunction is associated with MECP2 duplication syndrome and Rett syndrome (RTT), the phenotypes of which overlap with other NDDs, yet the precise molecular pathogenesis remains unclear. Using proximity-dependent biotinylation (BioID), we identified a novel TCF20 complex that interacts with MeCP2 through its subunit PHF14. TCF20 regulates the expression of key neuronal genes, many of which are co-regulated by MeCP2. Reducing Tcf20 partially rescued the behavioral deficits caused by MECP2 overexpression, underscoring a functional relationship between MeCP2 and TCF20 in NDD pathogenesis. We identified a patient with a missense mutation in PHF14 that abolishes the MeCP2-PHF14-TCF20 interaction who exhibits neurological features seen in RTT. These data demonstrate the critical role of MeCP2-TCF20 complex interaction for brain function.
2022-01-24 | GSE179229 | GEO