Project description:To identify the activity-induced gene expression programs in inhibitory and excitatory neurons, we analyzed RNA extracted from cultured E14 mouse MGE- and CTX-derived neurons (DIV 10) after these cultures were membrane-depolarized for 0, 1 and 6 hrs with 55mM extracellular KCl. To identify the gene programs regulated in these cells by the activity-induced early-response transcription factor Npas4, we repeated the same experiment in the MGE- and CTX-cultures lacking Npas4 (Npas4-KO). Littermate mouse E14 MGE- or CTX-derived neurons (WT or KO for Npas4) were cultured for 9 days, quieted overnight with TTX and AP-5 and then membrane-depolarized for 0, 1 or 6 hours by raising the extracellular KCl-concentration to 55mM. RNA was then extracted and analyzed using Affymetrix GeneChip Mouse Expression Set 430 2.0 microarray platform.
Project description:To identify the activity-induced gene expression programs in inhibitory and excitatory neurons, we analyzed RNA extracted from cultured E14 mouse MGE- and CTX-derived neurons (DIV 10) after these cultures were membrane-depolarized for 0, 1 and 6 hrs with 55mM extracellular KCl. To identify the gene programs regulated in these cells by the activity-induced early-response transcription factor Npas4, we repeated the same experiment in the MGE- and CTX-cultures lacking Npas4 (Npas4-KO).
Project description:we used DNA microarray analysis to identify genes that are induced by neuronal activity in excitatory neurons at the time when inhibitory synapses are forming and maturing on them. Experiment Overall Design: We cultured cortical neurons for 7 DIV until the process of inhibitory synapse development was underway, and then depolarized the neurons with 50 mM of KCl to activate L-type voltage-sensitive calcium channels (L-VSCCs) for 0, 1 or 6 hours, the cells were lysed, mRNA isolated and hybridized to Affymetrix arrays. Data were collected from 3 independent experiments.
Project description:This SuperSeries is composed of the following subset Series:; GSE11256: KCl depolarization-regulated genes in mouse cortical neurons; GSE11258: Npas4-regulated genes in mouse hippocampal neurons Experiment Overall Design: Refer to individual Series
Project description:Neuronal activity induces topoisomerase IIb (TOP2B) to form DNA double strand breaks (DSBs) within the promoters of specific early response genes (ERGs), such as Fos, FosB, and Npas4, and these DSBs facilitate rapid ERG transcription. Yet how activity-induced DSBs are repaired and the significance of such mechanisms for neuronal function remain unclear. Here we show that the proteasome and the enzyme, tyrosyl-DNA phosphodiesterase 2 (TDP2), catalyze the initial processing of TOP2B-mediated DSBs in neurons. Knockdown of Tdp2 delayed the repair of neuronal activity-induced DSBs and prolonged the expression of ERGs in primary mouse cortical neurons, indicating that TDP2-mediated DNA repair is essential for the temporal control of ERG transcription. Deletion of Tdp2 in excitatory forebrain neurons caused DSB accrual and ERG overexpression, and these changes were associated with increased excitatory synaptic transmission and cortical circuit dysfunction. Mutations in TDP2 cause the disease, SCAR23 (spinocerebellar ataxia, autosomal recessive 23), which manifests predominantly with neurological abnormalities. We show that whereas proliferating cells possess redundant pathways to process TOP2B-mediated DSBs, these pathways are relatively inactive in postmitotic neurons. Together, these results underscore the neuroprotective roles of TDP2 and suggest that activity-induced DSBs could be relevant sources of DNA lesions for neurodegeneration.
Project description:The development of cortical circuits, made up of excitatory neurons and inhibitory interneurons, is a fine-tuned and vital process during brain development. Aberrations affecting the establishment of these circuits are implicated in several neuropsychiatric and neurological disorders. While excitatory neurons originate in cortical proliferative zones, inhibitory interneurons migrate from the basal telencephalon into the cortex. This migration is regulated by intrinsic genetic programs and extrinsic cues. Here, we aimed to identify the role of the DNA methyltransferase 1 (DNMT1) in controlling the expression of key genes implicated in the development and migration of post-mitotic somatostatin-positive interneurons as well as its impact on the rest of the cortical population.
Project description:The cerebral cortex comprises diverse excitatory and inhibitory neuron subtypes, each with distinct laminar positions and connectivity patterns. Yet, the molecular logic underlying their precise wiring remains poorly understood. To identify ligand–receptor (LR) interactions involved in cortical circuit assembly, we tracked gene expression dynamics across major neuronal populations at 17 developmental stages using single-cell transcriptomics. This generated a comprehensive atlas of LR-mediated communication between excitatory and inhibitory neuron subtypes, capturing known and novel interactions. Notably, we identify neogenin-1 as the principal receptor for Cbln4 during the perinatal period, mediating synapse formation between somatostatin-expressing interneurons and glutamatergic neurons. We also identify cadherin superfamily members as candidate regulators of perisomatic inhibition onto deep and superficial excitatory neurons by parvalbumin-expressing basket cells, with opposing effects on synapse formation. These findings suggest a context-dependent role for cadherins in synaptic specificity and underscore the power of single-cell transcriptomics for decoding molecular mechanisms of cortical wiring.
Project description:The cerebral cortex comprises diverse excitatory and inhibitory neuron subtypes, each with distinct laminar positions and connectivity patterns. Yet, the molecular logic underlying their precise wiring remains poorly understood. To identify ligand–receptor (LR) interactions involved in cortical circuit assembly, we tracked gene expression dynamics across major neuronal populations at 17 developmental stages using single-cell transcriptomics. This generated a comprehensive atlas of LR-mediated communication between excitatory and inhibitory neuron subtypes, capturing known and novel interactions. Notably, we identify neogenin-1 as the principal receptor for Cbln4 during the perinatal period, mediating synapse formation between somatostatin-expressing interneurons and glutamatergic neurons. We also identify cadherin superfamily members as candidate regulators of perisomatic inhibition onto deep and superficial excitatory neurons by parvalbumin-expressing basket cells, with opposing effects on synapse formation. These findings suggest a context-dependent role for cadherins in synaptic specificity and underscore the power of single-cell transcriptomics for decoding molecular mechanisms of cortical wiring.