NPTX2, Homeostatic Scaling, and Schizophrenia
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ABSTRACT:
PROVIDER: PRJNA633132 | ENA |
REPOSITORIES: ENA
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Project description:Schizophrenia is a complex genetic and developmental disorder. We present a model of disease resulting from disruption of a specific stage of homeostatic scaling (HS). HS modifies synapses and circuits in response to changes in neuronal activity and underlies cortical development and memory consolidation. Neuronal pentraxin 2 (NPTX2) plays a critical role in HS and its homeostatic action requires exocytosis at excitatory synapses on parvalbumin interneurons (PV) whereupon a portion is later shed into the CSF. CSF NPTX2 is reduced in two independent cohorts of patients with schizophrenia. To understand the relationship of this biomarker to disease we confirmed that in normal volunteers CSF NPTX2 increases rapidly with sleep deprivation consistent with behavior-linked exocytosis/shedding. In mouse neocortex NPTX2 exocytosis/shedding are activity-dependent and coupled to circadian behavioral. By contrast, in mouse genetic models that interrupt early events in HS NPTX2 exocytosis/shedding are erratic and not linked to behavior. The vital contribution of NPTX2 to homeostasis is revealed in Nptx2-/- mice, which exhibit sensitivity to social isolation stress and multiple schizophrenia-domain phenotypes. NPTX2 is not implicated by human genome studies; rather we propose that diverse mutations linked to schizophrenia disrupt activity-dependent mechanisms required for NPTX2 function. The ability to monitor NPTX2 in human subjects provides an opportunity to translate fundamental neuroscience to human neuropsychiatric disease.
2021-05-15 | GSE150671 | GEO
Project description:Neuronal networks are subject to fluctuations in both the magnitude and frequency of inputs, requiring plasticity mechanisms to stabilize network activity. Homeostatic synaptic scaling is a form of synaptic plasticity that adjusts the strength of neuronal connections up or down in response to large changes in input. Although homeostatic plasticity requires changes in gene expression, there is only limited data describing the molecular changes associated with homeostatic scaling, focusing mostly on the expression mechanisms involving glutamate receptors. The fact that neuronal networks can be scaled up (in response to reduced activity) or down (in response to enhanced activity) provides a unique opportunity to examine the molecular and proteomic response to opposite ends of the phenotypic spectrum of synaptic plasticity. Here we first demonstrate that homeostatic scaling required protein synthesis. We then examined the plasticity-induced changes in the newly-synthesized neuronal proteome of neurons to identify the landscape of proteomic changes that contribute to opposing forms of homeostatic plasticity. Cultured rat hippocampal neurons (21 DIV) underwent homeostatic upscaling or downscaling (treatments with TTX and Bicucculine, respectively). We used BONCAT (BioOrthogonal Non-Canonical Amino acid Tagging) to metabolically label, capture and identify newly-synthesized proteins, detecting and analysing 5940 newly-synthesized proteins using liquid chromatography-coupled tandem mass spectrometry and label-free quantitation. Neither up- or down-scaling produced changes in the number of different proteins translated. Rather, our findings indicate that synaptic up- and down-scaling elicit opposing translational regulation of several molecular pathways, producing targeted adjustments in the neuronal proteome. We detected ~ 300 differentially regulated proteins involved in neurite outgrowth, reorganization of nerve terminals, axon guidance and targeting, neurotransmitter transport, filopodia assembly, excitatory synapses and glutamate receptor complexes. These proteins include well-characterized mediators of synaptic plasticity, e.g. the ionotropic glutamate receptor complex that is down-regulated during down-scaling and coordinately upregulated during upscaling. We also identified differentially regulated proteins that in addition to their regulation in homeostatic plasticity, are also associated with multiple diseases and disorders, including intellectual disability, schizophrenia, epilepsy, and Parkinson’s disease.
2016-12-22 | PXD004889 | Pride
Project description:Homeostatic scaling adjusts synaptic strength in response to persistent changes in neuronal network activity. This compensatory mechanism requires proteome remodeling accomplished via regulation of protein synthesis as well as degradation, but the global patterns of proteome remodeling and the underlying dynamics of individual proteins remain elusive. Here we used dynamic SILAC labeling in cultured hippocampal cells to identify proteins involved in homeostatic up- or down-scaling and to quantify their changes in synthesis and degradation as well as resulting changes in protein abundance or turnover. Our data demonstrate that a large fraction of the neuronal proteome is remodeled during homeostatic scaling. Most proteins were down-regulated by decreased synthesis or up-regulated by decreased degradation. Comparably fewer proteins showed increased synthesis or degradation rates. More than half of the quantified synaptic proteins were regulated, including pre- as well as postsynaptic proteins with diverse molecular functions.
2020-03-31 | PXD016004 | Pride
Project description:Homeostatic plasticity, a form of synaptic plasticity, maintains the fine balance between overall excitation and inhibition in developing and mature neuronal networks. Although the synaptic mechanisms of homeostatic plasticity are well characterized, the associated transcriptional program remains poorly understood. We show that the Kleefstra syndrome-associated protein, EHMT1, plays a critical and cell-autonomous role in synaptic scaling by responding to attenuated neuronal firing or sensory drive. Chronic activity deprivation increased the amount of neuronal dimethylated H3 at lysine 9 (H3K9me2), the catalytic product of EHMT1 and an epigenetic marker for gene repression. Genetic knockdown and pharmacological blockade of EHMT1 or EHMT2 prevented the increase of H3K9me2 and synaptic scaling up. Furthermore, BDNF repression was preceded by EHMT1/2-mediated H3K9me2 deposition at the Bdnf promoter during synaptic scaling up, both in vivo or in vivo. These findings suggest that changes in chromatin state through H3K9me2 governs a repressive program to achieve synaptic scaling. 12 samples (4 conditions in biological triplicate), 3 wt, 3 wt tetradotoxin treated, 3 k.d., 3 k.d. tetradotoxin treated
2016-06-30 | E-GEOD-68960 | biostudies-arrayexpress
Project description:Homeostatic scaling is a global form of synaptic plasticity used by neurons to adjust overall synaptic weight and maintain neuronal firing rates while protecting information coding. While homeostatic scaling has been demonstrated in vitro, a clear physiological function of this plasticity type has not been defined. Sleep is an essential process that modifies synapses to support cognitive functions such as learning and memory. Evidence suggests that information coding during wake drives synapse strengthening which is offset by weakening of synapses during sleep .Here we use biochemical fractionation, proteomics and in vivo two-photon imaging to characterize wide-spread changes in synapse composition in mice through the wake/sleep cycle. We find that during the sleep phase, synapses are weakened through dephosphorylation and removal of synaptic AMPA-type glutamate receptors (AMPARs) driven by the immediate early gene Homer1a and signaling from group I metabotropic glutamate receptors (mGluR1/5), consistent with known mechanisms of homeostatic scaling-down in vitro. Further, we find that these changes are important in the consolidation of contextual memories. While Homer1a gene expression is driven by neuronal activity during wake, Homer1a protein targeting to synapses serves as an integrator of arousal and sleep need through signaling by the wake-promoting neuromodulator noradrenaline (NA) and sleep-promoting modulator adenosine. During sleep or periods of increased sleep need Homer1a enters synapses where it remodels mGluR1/5 signaling complexes to promote AMPAR removal. Thus, we have characterized widespread changes occurring at synapses through the wake/sleep cycle and demonstrated that known mechanisms of homeostatic scaling-down previously demonstrated only in vitro are active in the brain during sleep to remodel synapses, contributing to memory consolidation.
2017-02-13 | PXD004537 | Pride
Project description:Homeostatic plasticity, a form of synaptic plasticity, maintains the fine balance between overall excitation and inhibition in developing and mature neuronal networks. Although the synaptic mechanisms of homeostatic plasticity are well characterized, the associated transcriptional program remains poorly understood. We show that the Kleefstra syndrome-associated protein, EHMT1, plays a critical and cell-autonomous role in synaptic scaling by responding to attenuated neuronal firing or sensory drive. Chronic activity deprivation increased the amount of neuronal dimethylated H3 at lysine 9 (H3K9me2), the catalytic product of EHMT1 and an epigenetic marker for gene repression. Genetic knockdown and pharmacological blockade of EHMT1 or EHMT2 prevented the increase of H3K9me2 and synaptic scaling up. Furthermore, BDNF repression was preceded by EHMT1/2-mediated H3K9me2 deposition at the Bdnf promoter during synaptic scaling up, both in vivo or in vivo. These findings suggest that changes in chromatin state through H3K9me2 governs a repressive program to achieve synaptic scaling.
2016-06-30 | GSE68960 | GEO
Project description:Synaptic scaling is a form of homeostatic plasticity which allows neurons to reduce their action potential firing rate in response to chronic alterations in neural activity. Synaptic scaling requires profound changes in gene expression, but the relative contribution of local and cell-wide mechanisms to synaptic scaling is controversial. Here we performed a comprehensive multi-omics characterization of the somatic and process compartments of primary rat hippocampal neurons during synaptic scaling. Thereby, we uncovered highly compartment-specific and correlated changes in the neuronal transcriptome and proteome. Specifically, we identified highly compartment-specific downregulation of crucial regulators of neuronal excitability and excitatory synapse structure. Motif analysis further suggests an important role for trans-acting post-transcriptional regulators, including RNA-binding proteins and microRNAs, in the local regulation of the corresponding mRNAs. Altogether, our study indicates that compartmentalized gene expression changes are widespread in synaptic scaling and might co-exist with neuron-wide mechanism to allow synaptic computation and homeostasis.
2021-07-06 | GSE155540 | GEO
Project description:In homeostatic scaling, the cellular mechanisms that detect the offset from the set-point, the duration of the offset and implement a cellular response are not well-understood. To understand the time-dependent dynamics,we manipulated activity for 2 hrs to induce the process of up or down-scaling and metabolically labelled nascent proteins using BONCAT. We analyzed the newly synthesized proteins that exhibited significant increases or decreases in expression in response to activity manipulations and identified 168 proteins. Then, to obtain a temporal trajectory of the cellular response, we compared the proteins synthesized within 2 and 24 hrs of an activity manipulation. Surprisingly, there was little overlap in the significantly regulated newly synthesized proteins identified in the early- and late-response datasets. There was, however, overlap in the functional categories that are modulated early and late, indicating that within protein function groups, different proteomic choices can be made to effect early and late homeostatic responses.
2018-02-16 | PXD008271 | Pride
Project description:Compartment-specific regulation of gene expression orchestrates homeostatic synaptic scaling
| PRJNA650210 | ENA
Project description:Synaptic scaling is a form of homeostatic plasticity which allows neurons to adjust their action potential firing rate in response to chronic alterations in neural activity. Synaptic scaling requires profound changes in gene expression, but the relative contribution of local and cell-wide mechanisms is controversial. Here we performed a comprehensive multi-omics characterization of the somatic and process compartments of primary rat hippocampal neurons during synaptic scaling. Thereby, we uncovered highly compartment-specific and correlated changes in the neuronal transcriptome and proteome. Specifically, we identified highly compartment-specific downregulation of crucial regulators of neuronal excitability and excitatory synapse structure. Motif analysis further suggests an important role for trans-acting post-transcriptional regulators, including RNA-binding proteins and microRNAs, in the local regulation of the corresponding mRNAs. Altogether, our study indicates that compartmentalized gene expression changes are widespread in synaptic scaling and might co-exist with neuron-wide mechanisms to allow synaptic computation and homeostasis
2021-07-09 | PXD020745 | Pride