Astrocytes derived from ASD patients alter behavior and destabilize neuronal activity through aberrant Ca2+ signaling

AbstractThe cellular mechanisms of Autism Spectrum Disorder (ASD) are poorly understood. Cumulative evidence suggests that abnormal synapse function underlies many features of this disease. Astrocytes play in several key neuronal processes, including the formation of synapses and the modulation of synaptic plasticity. Astrocyte abnormalities have also been identified in the postmortem brain tissue of ASD patients. However, it remains unclear whether astrocyte pathology plays a mechanistic role in ASD, as opposed to a compensatory response. To address this, we strategically combined stem cell culturing with transplantation techniques to determine disease specific properties inherent to patient derived astrocytes. We demonstrate that ASD astrocytes induce repetitive behavior as well as impair memory and long-term potentiation when transplanted into the healthy mouse brain. These in vivo phenotypes were accompanied by reduced neuronal network activity and spine density caused by ASD astrocytes in hippocampal neurons in vitro. Transplanted ASD astrocytes also exhibit exaggerated Ca2+ fluctuations in chimeric brains. Genetic modulation of evoked Ca2+ responses in ASD astrocytes modulates behavior and neuronal activity deficits. Thus, we determine that ASD patient astrocytes are sufficient to induce repetitive behavior as well as cognitive deficit, suggesting a previously unrecognized primary role for astrocytes in ASD.

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Aη-α and Aη-β peptides impair LTP ex vivo within the low nanomolar range and impact neuronal activity in vivo

Alzheimer s Research & Therapy ◽

10.1186/s13195-021-00860-1 ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Maria Mensch ◽

Jade Dunot ◽

Sandy M. Yishan ◽

Samuel S. Harris ◽

Aline Blistein ◽

...

Keyword(s):

Neuronal Activity ◽

Ex Vivo ◽

Long Term Potentiation ◽

Network Activity ◽

Strongly Correlated ◽

App Processing ◽

Term Potentiation ◽

Hippocampal Network

Abstract Background Amyloid precursor protein (APP) processing is central to Alzheimer’s disease (AD) etiology. As early cognitive alterations in AD are strongly correlated to abnormal information processing due to increasing synaptic impairment, it is crucial to characterize how peptides generated through APP cleavage modulate synapse function. We previously described a novel APP processing pathway producing η-secretase-derived peptides (Aη) and revealed that Aη–α, the longest form of Aη produced by η-secretase and α-secretase cleavage, impaired hippocampal long-term potentiation (LTP) ex vivo and neuronal activity in vivo. Methods With the intention of going beyond this initial observation, we performed a comprehensive analysis to further characterize the effects of both Aη-α and the shorter Aη-β peptide on hippocampus function using ex vivo field electrophysiology, in vivo multiphoton calcium imaging, and in vivo electrophysiology. Results We demonstrate that both synthetic peptides acutely impair LTP at low nanomolar concentrations ex vivo and reveal the N-terminus to be a primary site of activity. We further show that Aη-β, like Aη–α, inhibits neuronal activity in vivo and provide confirmation of LTP impairment by Aη–α in vivo. Conclusions These results provide novel insights into the functional role of the recently discovered η-secretase-derived products and suggest that Aη peptides represent important, pathophysiologically relevant, modulators of hippocampal network activity, with profound implications for APP-targeting therapeutic strategies in AD.

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Pharmacological intervention to restore connectivity deficits of neuronal networks derived from ASD patient iPSC with a TSC2 mutation

Molecular Autism ◽

10.1186/s13229-020-00391-w ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Mouhamed Alsaqati ◽

Vivi M. Heine ◽

Adrian J. Harwood

Keyword(s):

Neuronal Network ◽

Electrode Array ◽

Network Connectivity ◽

Autism Spectrum ◽

Network Activity ◽

Inhibitory Synapses ◽

Pharmacological Intervention ◽

Spatial Connectivity ◽

Neuronal Network Activity

Abstract Background Tuberous sclerosis complex (TSC) is a rare genetic multisystemic disorder resulting from autosomal dominant mutations in the TSC1 or TSC2 genes. It is characterised by hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) pathway and has severe neurodevelopmental and neurological components including autism, intellectual disability and epilepsy. In human and rodent models, loss of the TSC proteins causes neuronal hyperexcitability and synaptic dysfunction, although the consequences of these changes for the developing central nervous system are currently unclear. Methods Here we apply multi-electrode array-based assays to study the effects of TSC2 loss on neuronal network activity using autism spectrum disorder (ASD) patient-derived iPSCs. We examine both temporal synchronisation of neuronal bursting and spatial connectivity between electrodes across the network. Results We find that ASD patient-derived neurons with a functional loss of TSC2, in addition to possessing neuronal hyperactivity, develop a dysfunctional neuronal network with reduced synchronisation of neuronal bursting and lower spatial connectivity. These deficits of network function are associated with elevated expression of genes for inhibitory GABA signalling and glutamate signalling, indicating a potential abnormality of synaptic inhibitory–excitatory signalling. mTORC1 activity functions within a homeostatic triad of protein kinases, mTOR, AMP-dependent protein Kinase 1 (AMPK) and Unc-51 like Autophagy Activating Kinase 1 (ULK1) that orchestrate the interplay of anabolic cell growth and catabolic autophagy while balancing energy and nutrient homeostasis. The mTOR inhibitor rapamycin suppresses neuronal hyperactivity, but does not increase synchronised network activity, whereas activation of AMPK restores some aspects of network activity. In contrast, the ULK1 activator, LYN-1604, increases the network behaviour, shortens the network burst lengths and reduces the number of uncorrelated spikes. Limitations Although a robust and consistent phenotype is observed across multiple independent iPSC cultures, the results are based on one patient. There may be more subtle differences between patients with different TSC2 mutations or differences of polygenic background within their genomes. This may affect the severity of the network deficit or the pharmacological response between TSC2 patients. Conclusions Our observations suggest that there is a reduction in the network connectivity of the in vitro neuronal network associated with ASD patients with TSC2 mutation, which may arise via an excitatory/inhibitory imbalance due to increased GABA-signalling at inhibitory synapses. This abnormality can be effectively suppressed via activation of ULK1.

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Adaptor protein APPL1 links neuronal activity to chromatin remodeling in cultured hippocampal neurons

Journal of Molecular Cell Biology ◽

10.1093/jmcb/mjaa058 ◽

2020 ◽

Author(s):

Yu Wu ◽

Xinyou Lv ◽

Haiting Wang ◽

Kai Qian ◽

Jinjun Ding ◽

...

Keyword(s):

Chromatin Remodeling ◽

Neuronal Activity ◽

Hippocampal Neurons ◽

Late Phase ◽

Adaptor Protein ◽

Long Term Potentiation ◽

Nuclear Accumulation ◽

Transcriptional Responses ◽

Axon Terminals ◽

Term Potentiation

Abstract Local signaling events at synapses or axon terminals are communicated to the nucleus to elicit transcriptional responses, and thereby translate information about the external environment into internal neuronal representations. This retrograde signaling is critical to dendritic growth, synapse development, and neuronal plasticity. Here, we demonstrate that neuronal activity induces retrograde translocation and nuclear accumulation of endosomal adaptor APPL1. Disrupting the interaction of APPL1 with Importin α1 abolishes nuclear accumulation of APPL1, which in turn decreases the levels of histone acetylation. We further demonstrate that retrograde translocation of APPL1 is required for the regulation of gene transcription and then maintenance of hippocampal late-phase long-term potentiation. Thus, these results illustrate an APPL1-mediated pathway that contributes to the modulation of synaptic plasticity via coupling neuronal activity with chromatin remodeling.

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Pharmacological intervention to restore connectivity deficits of neuronal networks derived from ASD patient iPSCs with a TSC2 mutation

10.21203/rs.3.rs-35221/v2 ◽

2020 ◽

Author(s):

Mouhamed Alsaqati ◽

Vivi M Heine ◽

Adrian J. Harwood

Keyword(s):

Neuronal Network ◽

Electrode Array ◽

Network Connectivity ◽

Autism Spectrum ◽

Network Activity ◽

Inhibitory Synapses ◽

Pharmacological Intervention ◽

Spatial Connectivity ◽

Neuronal Network Activity

Abstract Background Tuberous sclerosis complex (TSC) is a rare genetic multisystemic disorder resulting from autosomal dominant mutations in the TSC1 or TSC2 genes. It is characterised by hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) pathway and has severe neurodevelopmental and neurological components including autism, intellectual disability and epilepsy. In human and rodent models, loss of the TSC proteins causes neuronal hyperexcitability and synaptic dysfunction, although the consequences of these changes for the developing central nervous system is currently unclear.MethodsHere we apply Multi-electrode array (MEA)-based assays to study the effects of TSC2 loss on neuronal network activity using Autism Spectrum Disorder (ASD) patient-derived iPSCs. We examine both temporal synchronisation of neuronal bursting, and spatial connectivity between electrodes across the network. Results We find that ASD patient-derived neurons with a functional loss of TSC2, in addition to possessing neuronal hyperactivity, develop a dysfunctional neuronal network with reduced synchronisation of neuronal bursting and lower spatial connectivity. These deficits of network function are associated with elevated expression of genes for inhibitory GABA signalling and glutamate signalling, indicating a potential abnormality of synaptic inhibitory-excitatory signalling. mTORC1 activity functions within a homeostatic triad of protein kinases, mTOR, AMP-dependent protein Kinase 1 (AMPK), and Unc-51 like Autophagy Activating Kinase 1 (ULK1) that orchestrate the interplay of anabolic cell growth and catabolic autophagy while balancing energy and nutrient homeostasis. The mTOR inhibitor rapamycin suppresses neuronal hyperactivity, but does not increase synchronised network activity, whereas activation of AMPK restores some aspects of network activity. In contrast, the ULK1 activator, LYN-1604 increases the network behaviour, shortens the network burst lengths, and reduces the number of uncorrelated spikes.LimitationsAlthough a robust and consistent phenotype is observed across multiple independent iPSC cultures, the results are based on one patient. There may be more subtle differences between patients with different TSC2 mutations or differences of polygenic background within their genomes. This may affect the severity of the network deficit or the pharmacological response between TSC2 patients.ConclusionsOur observations suggest that there is a reduction in the network connectivity of the in vitro neuronal network associated with ASD patients with TSC2 mutation, which may arise via an excitatory/inhibitory imbalance due to increased GABA-signalling at inhibitory synapses. This abnormality can be effectively suppressed via activation of ULK1.

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Respiration competes with theta for modulating parietal cortex neurons

10.1101/707331 ◽

2019 ◽

Author(s):

Felix Jung ◽

Yevgenij Yanovsky ◽

Jurij Brankačk ◽

Adriano BL Tort ◽

Andreas Draguhn

Keyword(s):

Neuronal Activity ◽

Parietal Cortex ◽

Field Potential ◽

Anterior Cingulate ◽

Theta Oscillations ◽

Network Activity ◽

Coupled Oscillations ◽

Neuronal Network Activity ◽

Posterior Parietal ◽

The Brain

AbstractRecent work has shown that nasal respiration entrains local field potential (LFP) and neuronal activity in widespread regions of the brain. This includes non-olfactory regions where respiration-coupled oscillations have been described in different mammals, such as rodents, cats and humans. They may, thus, constitute a global signal aiding interregional communication. Nevertheless, the brain produces other widespread slow rhythms, such as theta oscillations, which also mediate long-range synchronization of neuronal activity. It is completely unknown how these different signals interact to control neuronal network activity. In this work, we characterized respiration- and theta-coupled activity in the posterior parietal cortex of mice. Our results show that respiration-coupled and theta oscillations have different laminar profiles, in which respiration preferentially entrains LFPs and units in more superficial layers, whereas theta modulation does not differ across the parietal cortex. Interestingly, we find that the percentage of theta-modulated units increases in the absence of respiration-coupled oscillations, suggesting that both rhythms compete for modulating parietal cortex neurons. We further show through intracellular recordings that synaptic inhibition is likely to play a role in generating respiration-coupled oscillations at the membrane potential level. Finally, we provide anatomical and electrophysiological evidence of reciprocal monosynaptic connections between the anterior cingulate and posterior parietal cortices, suggesting a possible source of respiration-coupled activity in the parietal cortex.

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Tonic GABAA conductance favors temporal over rate coding in the rat hippocampus

10.1101/738369 ◽

2019 ◽

Author(s):

Yulia Dembitskaya ◽

Yu-Wei Wu ◽

Alexey Semyanov

Keyword(s):

Synaptic Plasticity ◽

Long Term Potentiation ◽

Spike Timing ◽

Network Activity ◽

Neuronal Network Activity ◽

Term Potentiation ◽

Rate Coding ◽

Ambient Gaba ◽

Theta Burst

AbstractSynaptic plasticity is triggered by different patterns of neuronal network activity. Network activity leads to an increase in ambient GABA concentration and tonic activation of GABAA receptors. How tonic GABAA conductance affects synaptic plasticity during temporal and rate-based coding is poorly understood. Here, we show that tonic GABAA conductance differently affects long-term potentiation (LTP) induced by different stimulation patterns. The LTP based on a temporal spike - EPSP order (spike-timing-dependent [st] LTP) was not affected by exogenous GABA application. Backpropagating action potential, which enables Ca2+ entry through N-methyl-D-aspartate receptors (NMDARs) during stLTP induction, was only slightly reduced by the tonic conductance. In contrast, GABA application impeded LTP dependent on spiking rate (theta-burst-induced [tb] LTP) by reducing the EPSP bust response and, hence, NMDAR-mediated Ca2+ entry during tbLTP induction. Our results may explain the changes in different forms of memory under physiological and pathological conditions that affect tonic GABAA conductance.

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The K63 deubiquitinase CYLD modulates autism-like behaviors and hippocampal plasticity by regulating autophagy and mTOR signaling

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2110755118 ◽

2021 ◽

Vol 118 (47) ◽

pp. e2110755118

Author(s):

Elisa Colombo ◽

Guilherme Horta ◽

Mona K. Roesler ◽

Natascha Ihbe ◽

Stuti Chhabra ◽

...

Keyword(s):

Repetitive Behavior ◽

Long Term Potentiation ◽

Autism Spectrum ◽

Synaptic Function ◽

Mtor Signaling ◽

Behavioral Profile ◽

Term Potentiation ◽

Hippocampal Network ◽

Deficient Mice

Nondegradative ubiquitin chains attached to specific targets via Lysine 63 (K63) residues have emerged to play a fundamental role in synaptic function. The K63-specific deubiquitinase CYLD has been widely studied in immune cells and lately also in neurons. To better understand if CYLD plays a role in brain and synapse homeostasis, we analyzed the behavioral profile of CYLD-deficient mice. We found that the loss of CYLD results in major autism-like phenotypes including impaired social communication, increased repetitive behavior, and cognitive dysfunction. Furthermore, the absence of CYLD leads to a reduction in hippocampal network excitability, long-term potentiation, and pyramidal neuron spine numbers. By providing evidence that CYLD can modulate mechanistic target of rapamycin (mTOR) signaling and autophagy at the synapse, we propose that synaptic K63-linked ubiquitination processes could be fundamental in understanding the pathomechanisms underlying autism spectrum disorder.

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Involvement of p75NTR in the alteration of neuronal network activity by Aβ

10.21203/rs.2.15701/v1 ◽

2019 ◽

Author(s):

hucheng zhao

Keyword(s):

Neuronal Network ◽

Hippocampal Neurons ◽

Neuronal Cell Death ◽

Neuronal Cell ◽

Network Activity ◽

Neurotrophin Receptor ◽

P75 Neurotrophin Receptor ◽

Neuronal Viability ◽

Neuronal Network Activity ◽

Low Concentrations

Abstract Background：The aberrant accumulation of amyloid-beta (Aβ) in the neocortex and hippocampus is one of the initial causes of Alzheimer's disease (AD). The p75 neurotrophin receptor (p75NTR) has been proposed to mediate Aβ-induced neuronal cell death. Whether p75NTR is required for the effects of Aβ on neuronal network activity，remains unclear. Results: Our results show that low concentrations of Aβ42 did not affect neuronal viability and synapse number. However, the Aβ42 treatment decreased the neuronal network activity of cultured wild-type hippocampal neurons, including a significant decrease of Ca2+ oscillations, spontaneous postsynaptic activity and synaptic connectivity. Moreover, the Aβ42 treatment did not affect the neuronal network activity of Tg2576/p75NTR+/− and p75NTR+/− hippocampal neurons. Conclusion: These studies will shed new light on the pathogenesis of AD and aid the development of related drugs.

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L-type calcium channel contributions to intrinsic excitability and synaptic activity during basolateral amygdala postnatal development

Journal of Neurophysiology ◽

10.1152/jn.00606.2019 ◽

2020 ◽

Vol 123 (3) ◽

pp. 1216-1235

Author(s):

Yiming Zhang ◽

Esperanza Garcia ◽

Anne-Sophie Sack ◽

Terrance P. Snutch

Keyword(s):

Calcium Channels ◽

Neurological Disorders ◽

Basolateral Amygdala ◽

Autism Spectrum ◽

Bay K 8644 ◽

Synaptic Activity ◽

Network Activity ◽

Intrinsic Excitability ◽

Synaptic Currents ◽

Neuronal Network Activity

The amygdala contributes toward emotional processes such as fear, anxiety, and social cognition. Furthermore, evidence suggests that increased excitability of basolateral amygdala (BLA) principal neurons underlie certain neuropsychiatric disorders. Gain-of-function mutations in neuronal L-type calcium channels (LTCCs) are linked to neurodevelopmental diseases, including autism spectrum disorders (ASDs). While LTCCs are expressed throughout the BLA, direct evidence for increased LTCC activity affecting BLA excitability and potentially contributing to disease pathophysiology is lacking. In this study, we utilized a pharmacological approach to examine the contributions of LTCCs to BLA principal cell excitability and synaptic activity at immature (postnatal day 7, P7) and juvenile (P21) developmental stages. Acute upregulation of LTCC activity in brain slices by application of the agonist ( S)-Bay K 8644 resulted in increased intrinsic excitability properties including firing frequency response, plateau potential, and spike-frequency adaptation selectively in P7 neurons. Contrastingly, for P21 neurons, the main effect of ( S)-Bay K 8644 was to enhance burst firing. ( S)-Bay K 8644 increased spontaneous inhibitory synaptic currents at both P7 and P21 but did not affect evoked synaptic currents at either stage. ( S)-Bay K 8644 did not alter P7 spontaneous excitatory synaptic currents, although it increased current amplitude in P21 neurons. Overall, the results provide support for the notion that alteration of LTCC activity at specific periods of early brain development may lead to functional alterations to neuronal network activity and subsequently contribute to underlying mechanisms of amygdala-related neurological disorders. NEW & NOTEWORTHY The role of L-type calcium channels (LTCCs) in regulating neuronal electrophysiological properties during development remains unclear. We show that in basolateral amygdala principal neurons, an increase of LTCC activity alters both neuronal excitability and synaptic activity. The results also provide evidence for the distinct contributions of LTCCs at different stages of neurodevelopment and shed insight into our understanding of LTCC dysfunction in amygdala-related neurological disorders.

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Modulating effects of FGF12 variants on NaV1.2 and NaV1.6 associated with Developmental and Epileptic Encephalopathy and Autism Spectrum Disorder

10.1101/2021.12.03.471090 ◽

2021 ◽

Author(s):

Simone Seiffert ◽

Manuela Pendziwiat ◽

Tatjana Bierhals ◽

Himanshu Goel ◽

Niklas Schwarz ◽

...

Keyword(s):

Autism Spectrum Disorder ◽

Sodium Channel ◽

Neuronal Network ◽

Case Reports ◽

Autism Spectrum ◽

Epileptic Encephalopathy ◽

Spectrum Disorder ◽

Network Activity ◽

Channel Blockers ◽

Neuronal Network Activity

AbstractObjectiveFibroblast growth factor 12 (FGF12) may represent an important modulator of neuronal network activity and has been associated with developmental and epileptic encephalopathy (DEE). We sought to identify the underlying pathomechanism of FGF12-related disorders.MethodsPatients with pathogenic variants in FGF12 were identified through published case reports, GeneMatcher and whole exome sequencing of own case collections. The functional consequences of two missense variants and two copy number variants (CNVs) were studied by co-expression of wild-type and mutant FGF12 in neuronal-like cells (ND7/23) with the sodium channels NaV1.2 or NaV1.6, including their functional active beta-1 and beta-2 sodium channel subunits (SCN1B and SCN2B).ResultsFour variants in FGF12 were identified for functional analysis: one novel FGF12 variant in a patient with autism spectrum disorder and three variants from previously published patients affected by developmental and epileptic encephalopathy (DEE). We demonstrate the differential regulating effects of wildtype and mutant FGF12 on NaV1.2 and NaV1.6 channels. Here, FGF12 variants lead to a complex kinetic influence on Nav1.2 and Nav 1.6, including loss- as well as gain-of function changes in fast inactivation as well as loss-of function changes in slow inactivation.InterpretationFor the first time, we could demonstrate the detailed regulating effect of FGF12 on NaV1.2 and NaV1.6 and confirmed the complex effect of FGF12 on neuronal network activity. Our findings expand the phenotypic spectrum related to FGF12 variants and elucidate the underlying pathomechanism. Specific variants in FGF12-associated disorders may be amenable to precision treatment with sodium channel blockers.

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