Similar Datasets
Project description:Copy number variations (CNVs) at 7q11.23 cause Williams-Beuren (WBS) and 7q microduplication syndromes (7Dup). Both neurodevelopmental disorders (NDDs) feature mild to moderate intellectual disability, accompanied by symmetrically opposite neurocognitive and behavioral features. Although significant progress has been made in understanding the molecular mechanisms underlying 7q11.23-related pathophysiologies, the interplay between different layers of gene expression and the propagation of opposite symmetry arising from CNV remains elusive. Here, we uncovered 7q11.23 dosage-dependent symmetrically opposite dynamics in neuronal differentiation and intrinsic excitability. By integrating transcriptomics, translatomics and proteomics of patient-derived and isogenic induced neurons, we found that genes related to neuronal transmission follow 7q11.23 dosage and are transcriptionally controlled, while translational factors and ribosomal genes are post-transcriptionally buffered. Consistently, we found a deregulated mTOR pathway, with phospho-S6 (pS6) being downregulated in WBS and upregulated in 7Dup. Surprisingly phospho-4E-BP (p4E-BP) was going in the opposite direction, reflecting the total 4E-BP levels, thus highlighting the different roles of pS6 and p4E-BP during neurogenesis. Therefore, our work emphasizes the importance of multilayer research when investigating complex NDDs, highlighting ribosomal biogenesis and paving the way for novel treatments by uncoupling the role of pS6 and p4E-BPs in NDDs.
2024-03-20 | GSE261691 | GEO
Project description:Copy number variations (CNVs) at 7q11.23 cause Williams-Beuren (WBS) and 7q microduplication syndromes (7Dup). Both neurodevelopmental disorders (NDDs) feature mild to moderate intellectual disability, accompanied by symmetrically opposite neurocognitive and behavioral features. Although significant progress has been made in understanding the molecular mechanisms underlying 7q11.23-related pathophysiologies, the interplay between different layers of gene expression and the propagation of opposite symmetry arising from CNV remains elusive. Here, we uncovered 7q11.23 dosage-dependent symmetrically opposite dynamics in neuronal differentiation and intrinsic excitability. By integrating transcriptomics, translatomics and proteomics of patient-derived and isogenic induced neurons, we found that genes related to neuronal transmission follow 7q11.23 dosage and are transcriptionally controlled, while translational factors and ribosomal genes are post-transcriptionally buffered. Consistently, we found a deregulated mTOR pathway, with phospho-S6 (pS6) being downregulated in WBS and upregulated in 7Dup. Surprisingly phospho-4E-BP (p4E-BP) was going in the opposite direction, reflecting the total 4E-BP levels, thus highlighting the different roles of pS6 and p4E-BP during neurogenesis. Therefore, our work emphasizes the importance of multilayer research when investigating complex NDDs, highlighting ribosomal biogenesis and paving the way for novel treatments by uncoupling the role of pS6 and p4E-BPs in NDDs.
2024-03-20 | GSE261690 | GEO
Project description:Epigenetic modifications, such as DNA cytosine methylation, contribute to the mechanisms underlying learning and memory by coordinating adaptive gene expression and neuronal plasticity. Transcription-dependent plasticity regulated by DNA methylation includes synaptic plasticity and homeostatic synaptic scaling. Memory-related plasticity also includes alterations in intrinsic membrane excitability mediated by changes in the abundance or activity of ion channels in the plasma membrane, which sets the threshold for action potential generation. We found that prolonged inhibition of DNA methyltransferase (DNMT) activity increased intrinsic membrane excitability of cultured cortical pyramidal neurons. Knockdown of the cytosine demethylase TET1 or inhibition of RNA polymerase blocked the increased membrane excitability caused by DNMT inhibition, suggesting that this effect was mediated by subsequent cytosine demethylation and de novo transcription. Prolonged DNMT inhibition blunted the medium component of the after-hyperpolarization potential, an effect that would increase neuronal excitability, and was associated with reduced expression of the genes encoding small-conductance Ca(2+)-activated K(+) (SK) channels. Furthermore, the specific SK channel blocker apamin increased neuronal excitability but was ineffective after DNMT inhibition. Our results suggested that DNMT inhibition enables transcriptional changes that culminate in decreased expression of SK channel-encoding genes and decreased activity of SK channels, thus providing a mechanism for the regulation of neuronal intrinsic membrane excitability by dynamic DNA cytosine methylation. This study has implications for human neurological and psychiatric diseases associated with dysregulated intrinsic excitability.
| S-EPMC5709999 | biostudies-literature
Project description:Emerging data suggest an important relationship between sleep and Alzheimer's disease (AD), but how poor sleep promotes the development of AD remains unclear.Here, using a Drosophila model of AD, we provide evidence suggesting that changes in neuronal excitability underlie the effects of sleep loss on AD pathogenesis. ?-amyloid (A?) accumulation leads to reduced and fragmented sleep, while chronic sleep deprivation increases A? burden. Moreover, enhancing sleep reduces A? deposition. Increasing neuronal excitability phenocopies the effects of reducing sleep on A?, and decreasing neuronal activity blocks the elevated A? accumulation induced by sleep deprivation. At the single neuron level, we find that chronic sleep deprivation, as well as A? expression, enhances intrinsic neuronal excitability. Importantly, these data reveal that sleep loss exacerbates A?-induced hyperexcitability and suggest that defects in specific K(+) currents underlie the hyperexcitability caused by sleep loss and A? expression. Finally, we show that feeding levetiracetam, an anti-epileptic medication, to A?-expressing flies suppresses neuronal excitability and significantly prolongs their lifespan.Our findings directly link sleep loss to changes in neuronal excitability and A? accumulation and further suggest that neuronal hyperexcitability is an important mediator of A? toxicity. Taken together, these data provide a mechanistic framework for a positive feedback loop, whereby sleep loss and neuronal excitation accelerate the accumulation of A?, a key pathogenic step in the development of AD.
| S-EPMC4366315 | biostudies-literature
Project description:Genetically encoded pH-sensors are widely used in studying cell membrane trafficking and membrane protein turnover because they render exo-/endocytosis-associated pH changes to fluorescent signals. For imaging and analysis purposes, high concentration ammonium chloride is routinely used to alkalize intracellular membrane compartments under the assumption that it does not cause long-term effects on cellular processes being studied like neurotransmission. However, pathological studies about hyperammonemia have shown that ammonium is toxic to brain cells especially astrocytes and neurons. Here, we focus on ammonium's physiological impacts on neurons including membrane potential, cytosolic Ca2+ and synaptic vesicles. We have found that extracellularly applied ammonium chloride as low as 5 mM causes intracellular Ca2+-increase and a reduction of vesicle release even after washout. The often-used 50 mM ammonium chloride causes more extensive and persistent changes, including membrane depolarization, prolonged elevation of intracellular Ca2+ and diminution of releasable synaptic vesicles. Our findings not only help to bridge the discrepancies in previous studies about synaptic vesicle release using those pH-sensors or other vesicle specific reporters, but also suggest an intriguing relationship between intracellular pH and neurotransmission.
| S-EPMC5505971 | biostudies-literature
Project description:The basal ganglia are a group of subcortical nuclei that contribute to action selection and reinforcement learning. The principal neurons of the striatum, spiny projection neurons of the direct (dSPN) and indirect (iSPN) pathways, maintain low intrinsic excitability, requiring convergent excitatory inputs to fire. Here, we examined the role of autophagy in mouse SPN physiology and animal behavior by generating conditional knockouts of Atg7 in either dSPNs or iSPNs. Loss of autophagy in either SPN population led to changes in motor learning but distinct effects on cellular physiology. dSPNs, but not iSPNs, required autophagy for normal dendritic structure and synaptic input. In contrast, iSPNs, but not dSPNs, were intrinsically hyperexcitable due to reduced function of the inwardly rectifying potassium channel, Kir2. These findings define a novel mechanism by which autophagy regulates neuronal activity: control of intrinsic excitability via the regulation of potassium channel function.
| S-EPMC6984822 | biostudies-literature
Project description:Sensorineural hearing loss during early childhood alters auditory cortical evoked potentials in humans and profoundly changes auditory processing in hearing-impaired animals. Multiple mechanisms underlie the early postnatal establishment of cortical circuits, but one important set of developmental mechanisms relies on the neuromodulator serotonin (5-hydroxytryptamine [5-HT]). On the other hand, early sensory activity may also regulate the establishment of adultlike 5-HT receptor expression and function. We examined the role of 5-HT in auditory cortex by first investigating how 5-HT neurotransmission and 5-HT(2) receptors influence the intrinsic excitability of layer II/III pyramidal neurons in brain slices of primary auditory cortex (A1). A brief application of 5-HT (50 ?M) transiently and reversibly decreased firing rates, input resistance, and spike rate adaptation in normal postnatal day 12 (P12) to P21 rats. Compared with sham-operated animals, cochlear ablation increased excitability at P12-P21, but all the effects of 5-HT, except for the decrease in adaptation, were eliminated in both sham-operated and cochlear-ablated rats. At P30-P35, cochlear ablation did not increase intrinsic excitability compared with shams, but it did prevent a pronounced decrease in excitability that appeared 10 min after 5-HT application. We also tested whether the effects on excitability were mediated by 5-HT(2) receptors. In the presence of the 5-HT(2)-receptor antagonist, ketanserin, 5-HT significantly decreased excitability compared with 5-HT or ketanserin alone in both sham-operated and cochlear-ablated P12-P21 rats. However, at P30-P35, ketanserin had no effect in sham-operated and only a modest effect cochlear-ablated animals. The 5-HT(2)-specific agonist 5-methoxy-N,N-dimethyltryptamine also had no effect at P12-P21. These results suggest that 5-HT likely regulates pyramidal cell excitability via multiple receptor subtypes with opposing effects. These data also show that early sensorineural hearing loss affects the ability of 5-HT receptor activation to modulate A1 pyramidal cell excitability.
| S-EPMC2997032 | biostudies-literature
Project description:New neurons are added to the adult brain throughout life, but only half ultimately integrate into existing circuits. Sensory experience is an important regulator of the selection of new neurons but it remains unknown whether experience provides specific patterns of synaptic input or simply a minimum level of overall membrane depolarization critical for integration. To investigate this issue, we genetically modified intrinsic electrical properties of adult-generated neurons in the mammalian olfactory bulb. First, we observed that suppressing levels of cell-intrinsic neuronal activity via expression of ESKir2.1 potassium channels decreases, whereas enhancing activity via expression of NaChBac sodium channels increases survival of new neurons. Neither of these modulations affects synaptic formation. Furthermore, even when neurons are induced to fire dramatically altered patterns of action potentials, increased levels of cell-intrinsic activity completely blocks cell death triggered by NMDA receptor deletion. These findings demonstrate that overall levels of cell-intrinsic activity govern survival of new neurons and precise firing patterns are not essential for neuronal integration into existing brain circuits.
| S-EPMC2822732 | biostudies-literature
Project description:Kainic acid-induced status epilepticus (KA-SE) in mature rats results in the development of spontaneous recurrent seizures and a pattern of cell death resembling hippocampal sclerosis in patients with temporal lobe epilepsy. In contrast, KA-SE in young animals before postnatal day (P) 18 is less likely to cause cell death or epilepsy. To investigate whether changes in neuronal excitability occur in the subiculum after KA-SE, we examined the age-dependent effects of SE on the bursting neurons of subiculum, the major output region of the hippocampus. Patch-clamp recordings were used to monitor bursting in pyramidal neurons in the subiculum of rat hippocampal slices. Neurons were studied either one or 2-3 weeks following injection of KA or saline (control) in immature (P15) or more mature (P30) rats, which differ in their sensitivity to KA as well as the long-term sequelae of the KA-SE. A significantly greater proportion of subicular pyramidal neurons from P15 rats were strong-bursting neurons and showed increased frequency-dependent bursting compared to P30 animals. Frequency-dependent burst firing was enhanced in P30, but not in P15 rats following KA-SE. The enhancement of bursting induced by KA-SE in more mature rats suggests that the frequency-dependent limitation of repetitive burst firing, which normally occurs in the subiculum, is compromised following SE. These changes could facilitate the initiation of spontaneous recurrent seizures or their spread from the hippocampus to other parts of the brain.
| S-EPMC4361192 | biostudies-literature
Project description:Maturation of neuronal and synaptic functions during early life is essential for the development of neuronal circuits and behaviors. In newborns synaptic transmission at excitatory synapses is primarily mediated by N-methyl-D-aspartate receptors (NMDARs), and NMDAR-mediated signaling plays an important role in synaptic maturation. Concomitant with synapse development, the intrinsic properties of neurons undergo dramatic changes during early life. However, little is known about the role of NMDARs in the development of intrinsic excitability. By using mosaic deletion of the obligatory GluN1 subunit of NMDARs in the thalamus of newborn mice, we showed that NMDARs regulate neuronal excitability during postnatal development. Compared with neighboring control neurons, neurons lacking NMDARs exhibit hyperexcitability and this effect is present throughout early life. Morphological analyses show that thalamic neurons without NMDARs have smaller soma size and fewer dendritic branches. Deletion of NMDARs causes a reduction of hyperpolarization-activated cation (HCN) channel function in thalamic neurons, and pharmacologically blocking HCN channels in wild type neurons mimics the effects of GluN1 deletion on intrinsic excitability. Deletion of GluN1 down-regulated mechanistic target of rapamycin (mTOR) signaling in thalamic neurons, and mosaic deletion of mTOR recapitulated the effects of GluN1 deletion. Our results demonstrate that NMDARs regulate intrinsic excitability and morphology of thalamic neurons through cell autonomous mechanisms that implicate mTOR signaling.
| S-EPMC5674002 | biostudies-literature