Chronic modulation of cAMP signaling elicits synaptic scaling irrespective of activity
Ontology highlight
ABSTRACT:
SUBMITTER: Bagatelas E
PROVIDER: S-EPMC11233962 | biostudies-literature | 2024 Jun
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Homeostatic scaling allows neurons to maintain stable activity patterns by globally altering their synaptic strength in response to changing activity levels. Suppression of activity by blocking action potentials increases synaptic strength through an upregulation of surface AMPA receptors. Although this synaptic up-scaling was shown to require transcription, the molecular nature of the intrinsic transcription program underlying this process and its functional significance have been unclear. Using RNA-seq, we identified 73 genes that were specifically upregulated in response to activity suppression. In particular, Neuronal pentraxin-1 (Nptx1) increased within 6 h of activity blockade, and knockdown of this gene blocked the increase in synaptic strength. Notably, Nptx1 induction is mediated by calcium influx through the T-type Voltage-Gated Calcium Channel, as well as two transcription factors, SRF and ELK1. Taken together, these results uncover a transcriptional program that specifically operates when neuronal activity is suppressed, to globally coordinate the increase in synaptic strength.
2017-02-07 | GSE90988 | GEO
Project description:The influence of neural activity on astrocytes and their reciprocal interactions with neurons has emerged as an important modulator of synapse function. Astrocytes exhibit activity-dependent changes in gene expression, yet the molecular mechanisms by which they accomplish this have remained largely unknown. The molecular signaling pathway, Sonic hedgehog (Shh), mediates neuron-astrocyte communication and regulates the organization of cortical synapses. Here, we demonstrate that neural activity stimulates Shh signaling in cortical astrocytes and upregulates expression of Hevin and SPARC, astrocyte derived molecules that modify synapses. Whisker stimulation and chemogenetic activation both increase Shh activity in deep layers of the somatosensory cortex, where neuron-astrocyte Shh signaling is predominantly found. Experience-dependent Hevin and SPARC require intact Shh signaling and selective loss of pathway activity in astrocytes occludes experience-dependent structural plasticity. Taken together, these data identify Shh signaling as an activity-dependent, neuronal derived cue that stimulates astrocyte interactions with synapses and promotes synaptic plasticity.
| S-EPMC11195099 | biostudies-literature
Project description:Neurons adapt to long-lasting changes in network activity, both in vivo and in vitro, by adjusting their synaptic strengths to stabilize firing rates. We found that homeostatic scaling of excitatory synapses was impaired in hippocampal neurons derived from mice lacking presenilin 1 (Psen1(-/-) mice) or expressing a familial Alzheimer's disease-linked Psen1 mutation (Psen1(M146V)). These findings suggest that deficits in synaptic homeostasis may contribute to brain dysfunction in Alzheimer's disease.
| S-EPMC3164917 | biostudies-literature
Project description:Long-lasting forms of synaptic plasticity such as synaptic scaling are critically dependent on transcription. Activity-dependent transcriptional dynamics in neurons, however, remain incompletely characterized because most previous efforts relied on measurement of steady-state mRNAs. Here, we use nascent RNA sequencing to profile transcriptional dynamics of primary neuron cultures undergoing network activity shifts. We find pervasive transcriptional changes, in which ∼45% of expressed genes respond to network activity shifts. We further link retinoic acid-induced 1 (RAI1), the Smith-Magenis syndrome gene, to the transcriptional program driven by reduced network activity. Remarkable agreement among nascent transcriptomes, dynamic chromatin occupancy of RAI1, and electrophysiological properties of Rai1-deficient neurons demonstrates the essential roles of RAI1 in suppressing synaptic upscaling in the naive network, while promoting upscaling triggered by activity silencing. These results highlight the utility of bona fide transcription profiling to discover mechanisms of activity-dependent chromatin remodeling that underlie normal and pathological synaptic plasticity.
| S-EPMC7418709 | biostudies-literature
Project description:The physiological mechanisms driving synapse formation are elusive. Although numerous signals are known to regulate synapses, it remains unclear which signaling mechanisms organize initial synapse assembly. Here, we describe new tools, referred to as "SynTAMs" for synaptic targeting molecules, that enable localized perturbations of cAMP signaling in developing postsynaptic specializations. We show that locally restricted suppression of postsynaptic cAMP levels or of cAMP-dependent protein-kinase activity severely impairs excitatory synapse formation without affecting neuronal maturation, dendritic arborization, or inhibitory synapse formation. In vivo, suppression of postsynaptic cAMP signaling in CA1 neurons prevented formation of both Schaffer-collateral and entorhinal-CA1/temporoammonic-path synapses, suggesting a general principle. Retrograde trans-synaptic rabies virus tracing revealed that postsynaptic cAMP signaling is required for continuous replacement of synapses throughout life. Given that postsynaptic latrophilin adhesion-GPCRs drive synapse formation and produce cAMP, we suggest that spatially restricted postsynaptic cAMP signals organize assembly of postsynaptic specializations during synapse formation.
| S-EPMC8685283 | biostudies-literature
Project description:Neural systems use homeostatic plasticity to maintain normal brain functions and to prevent abnormal activity. Surprisingly, homeostatic mechanisms that regulate circuit output have mainly been demonstrated during artificial and/or pathological perturbations. Natural, physiological scenarios that activate these stabilizing mechanisms in neural networks of mature animals remain elusive. To establish the extent to which a naturally inactive circuit engages mechanisms of homeostatic plasticity, we utilized the respiratory motor circuit in bullfrogs that normally remains inactive for several months during the winter. We found that inactive respiratory motoneurons exhibit a classic form of homeostatic plasticity, up-scaling of AMPA-glutamate receptors. Up-scaling increased the synaptic strength of respiratory motoneurons and acted to boost motor amplitude from the respiratory network following months of inactivity. Our results show that synaptic scaling sustains strength of the respiratory motor output following months of inactivity, thereby supporting a major neuroscience hypothesis in a normal context for an adult animal.
| S-EPMC5636609 | biostudies-literature
Project description:Homeostatic scaling allows neurons to maintain stable activity patterns by globally altering their synaptic strength in response to changing activity levels. Suppression of activity by the blocking of action potentials increases synaptic strength through an upregulation of surface α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Although this synaptic upscaling was shown to require transcription, the molecular nature of the intrinsic transcription program underlying this process and its functional significance have been unclear. Using RNA-seq, we identified 73 genes that were specifically upregulated in response to activity suppression. In particular, Neuronal pentraxin-1 (Nptx1) increased within 6 hr of activity blockade, and knockdown of this gene blocked the increase in synaptic strength. Nptx1 induction is mediated by calcium influx through the T-type voltage-gated calcium channel, as well as two transcription factors, SRF and ELK1. Altogether, these results uncover a transcriptional program that specifically operates when neuronal activity is suppressed to globally coordinate the increase in synaptic strength.
| S-EPMC5524384 | biostudies-literature
Project description:Neural circuits utilize a host of homeostatic plasticity mechanisms, including synaptic scaling, to maintain stability in circuits undergoing experience-dependent remodeling necessary for information processing. During synaptic scaling, compensatory adaptations in synaptic strength are induced after chronic manipulations in neuronal firing, but our understanding of this process is largely limited to its initial induction. How these homeostatic synaptic adaptations evolve when activity renormalizes and their impact on subsequent homeostatic compensation are both poorly understood. To examine these issues, we investigated whether a previous history of homeostatic scaling in networks of cultured hippocampal neurons altered their subsequent homeostatic responses to chronic activity manipulations. Unexpectedly, we found that a history of synaptic scaling strongly suppressed future scaling to the same, and even opposite, activity challenges. This history-dependent suppression was specific for future homeostatic compensation, as networks with a prior scaling history showed no deficits in the chemical induction of long-term potentiation (cLTP), a Hebbian form of synaptic plasticity. Hippocampal neurons with a prior scaling history exhibited normal engagement of activity-dependent signaling during subsequent activity challenges (as assessed by examination of the ERK/MAPK pathway) but demonstrated widespread alterations in activity-dependent transcriptional
2024-09-01 | GSE180993 | GEO
Project description:The regulation of neurons by circadian clock genes is thought to contribute to the maintenance of neuronal functions that ultimately underlie animal behavior. However, the impact of specific circadian genes on cellular and molecular mechanisms controlling synaptic plasticity and cognitive function remains elusive. Here, we show that the expression of the circadian protein TIMELESS displays circadian rhythmicity in the mammalian hippocampus. We identify TIMELESS as a chromatin-bound protein that targets synaptic-plasticity-related genes such as phosphodiesterase 4B (Pde4b). By promoting Pde4b transcription, TIMELESS negatively regulates cAMP signaling to modulate AMPA receptor GluA1 function and influence synaptic plasticity. Conditional deletion of Timeless in the adult forebrain impairs working and contextual fear memory in mice. These cognitive phenotypes were accompanied by attenuation of hippocampal Schaffer-collateral synapse long-term potentiation. Together, these data establish a neuron-specific function of mammalian TIMELESS by defining a mechanism that regulates synaptic plasticity and cognitive function.
| S-EPMC10564971 | biostudies-literature
Project description:AimsSigma-1 receptors are involved in the pathophysiological process of several neuropsychiatric diseases such as epilepsy, depression. Allosteric modulation represents an important mechanism for receptor functional regulation. In this study, we examined antidepressant activity of the latest identified novel and selective allosteric modulator of sigma-1 receptor 3-methyl-phenyl-2, 3, 4, 5-tetrahydro-1H-benzo[d]azepin-7-ol (SOMCL-668).Methods and resultsA single administration of SOMCL-668 decreased the immobility time in the forced swimming test (FST) and tailing suspended test in mice, which were abolished by pretreatment of sigma-1 receptor antagonist BD1047. In the chronic unpredicted mild stress (CUMS) model, chronic application of SOMCL-668 rapidly ameliorated anhedonia-like behavior (within a week), accompanying with the enhanced expression of brain-derived neurotrophic factor (BDNF) and phosphorylation of glycogen synthase kinase 3β (GSK3β) (Ser-9) in the hippocampus. SOMCL-668 also rapidly promoted the phosphorylation of GSK3β (Ser-9) in an allosteric manner in vitro. In the cultured primary neurons, SOMCL-668 enhanced the sigma-1 receptor agonist-induced neurite outgrowth and the secretion of BDNF.ConclusionSOMCL-668, a novel allosteric modulator of sigma-1 receptors, elicits a potent and rapid acting antidepressant effect. The present data provide the first evidence that allosteric modulation of sigma-1 receptors may represent a new approach for antidepressant drug discovery.
| S-EPMC6492821 | biostudies-literature