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

Spatial Connectivity ◽

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.

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 ◽

Spatial Connectivity ◽

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.

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

10.21203/rs.3.rs-35221/v3 ◽

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 ◽

Spatial Connectivity ◽

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.Methods Here 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.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.

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

10.21203/rs.3.rs-35221/v1 ◽

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 ◽

Spatial Connectivity ◽

Abstract BackgroundTuberous 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.ResultsWe find that TSC2 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 decreased expression of those for glutamate signalling, indicating an imbalance of synaptic inhibitory-excitatory signalling. mTORC1 activity functions within a homeostatic triad of protein kinases, AMP-dependent protein Kinase 1 (AMPK), mTORC1 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 mTORC1 inhibitor rapamycin suppresses neuronal hyperactivity, but does not increase network activity, whereas activation of AMPK restores network activity without affecting the network burst length or regularity. 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 clones, the results are based on iPSC from 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 deficit can be effectively suppressed via activation of ULK1.

Extracellular matrix supports excitation-inhibition balance in neuronal networks by stabilizing inhibitory synapses

10.1101/2020.07.13.200113 ◽

2020 ◽

Author(s):

Egor Dzyubenko ◽

Michael Fleischer ◽

Daniel Manrique-Castano ◽

Mina Borbor ◽

Christoph Kleinschnitz ◽

...

Keyword(s):

Extracellular Matrix ◽

Neuronal Network ◽

Neuronal Plasticity ◽

Neuronal Networks ◽

Network Activity ◽

Inhibitory Synapses ◽

Neuronal Network Activity ◽

The Brain

AbstractMaintaining the balance between excitation and inhibition is essential for the appropriate control of neuronal network activity. Sustained excitation-inhibition (E-I) balance relies on the orchestrated adjustment of synaptic strength, neuronal activity and network circuitry. While growing evidence indicates that extracellular matrix (ECM) of the brain is a crucial regulator of neuronal excitability and synaptic plasticity, it remains unclear whether and how ECM contributes to neuronal circuit stability. Here we demonstrate that the integrity of ECM supports the maintenance of E-I balance by retaining inhibitory connectivity. Depletion of ECM in mature neuronal networks preferentially decreases the density of inhibitory synapses and the size of individual inhibitory postsynaptic scaffolds. After ECM depletion, inhibitory synapse strength homeostatically increases via the reduction of presynaptic GABAB receptors. However, the inhibitory connectivity reduces to an extent that inhibitory synapse scaling is no longer efficient in controlling neuronal network activity. Our results indicate that the brain ECM preserves the balanced network state by stabilizing inhibitory synapses.Significance statementThe question how the brain’s extracellular matrix (ECM) controls neuronal plasticity and network activity is key for an appropriate understanding of brain functioning. In this study, we demonstrate that ECM depletion much more strongly affects the integrity of inhibitory than excitatory synapses in vitro and in vivo. We revealed that by retaining inhibitory connectivity, ECM ensures the efficiency of inhibitory control over neuronal network activity. Our work significantly expands our current state of knowledge about the mechanisms of neuronal network activity regulation. Our findings are similarly relevant for researchers working on the physiological regulation of neuronal plasticity in vitro and in vivo and for researchers studying the remodeling of neuronal networks upon brain injury, where prominent ECM alterations occur.

Essential role for InSyn1 in dystroglycan complex integrity and cognitive behaviors in mice

eLife ◽

10.7554/elife.50712 ◽

2019 ◽

Vol 8 ◽

Author(s):

Akiyoshi Uezu ◽

Erin Hisey ◽

Yoshihiko Kobayashi ◽

Yudong Gao ◽

Tyler WA Bradshaw ◽

...

Keyword(s):

Neuronal Network ◽

Neuronal Firing ◽

Network Activity ◽

Inhibitory Synapses ◽

Molecular Architecture ◽

Synaptic Organization ◽

Cognitive Behaviors ◽

Human mutations in the dystroglycan complex (DGC) result in not only muscular dystrophy but also cognitive impairments. However, the molecular architecture critical for the synaptic organization of the DGC in neurons remains elusive. Here, we report Inhibitory Synaptic protein 1 (InSyn1) is a critical component of the DGC whose loss alters the composition of the GABAergic synapses, excitatory/inhibitory balance in vitro and in vivo, and cognitive behavior. Association of InSyn1 with DGC subunits is required for InSyn1 synaptic localization. InSyn1 null neurons also show a significant reduction in DGC and GABA receptor distribution as well as abnormal neuronal network activity. Moreover, InSyn1 null mice exhibit elevated neuronal firing patterns in the hippocampus and deficits in fear conditioning memory. Our results support the dysregulation of the DGC at inhibitory synapses and altered neuronal network activity and specific cognitive tasks via loss of a novel component, InSyn1.

Dementia with Lewy bodies—associated ß-synuclein mutations V70M and P123H cause mutation-specific neuropathological lesions

Human Molecular Genetics ◽

10.1093/hmg/ddab036 ◽

2021 ◽

Author(s):

Maryna Psol ◽

Sofia Guerin Darvas ◽

Kristian Leite ◽

Sameehan U Mahajani ◽

Mathias Bähr ◽

...

Keyword(s):

Neuronal Network ◽

Dementia With Lewy Bodies ◽

Lewy Bodies ◽

Sporadic Case ◽

Network Activity ◽

Proteinase K ◽

Neuronal Network Activity ◽

Distinct Disease

Abstract ß-Synuclein (ß-Syn) has long been considered to be an attenuator for the neuropathological effects caused by the Parkinson’s disease-related α-Synuclein (α-Syn) protein. However, recent studies demonstrated that overabundant ß-Syn can form aggregates and induce neurodegeneration in CNS neurons in vitro and in vivo, albeit at a slower pace as compared to α-Syn. Here we demonstrate that ß-Syn mutants V70M, detected in a sporadic case of Dementia with Lewy Bodies (DLB), and P123H, detected in a familial case of DLB, robustly aggravate the neurotoxic potential of ß-Syn. Intriguingly, the two mutations trigger mutually exclusive pathways. ß-Syn V70M enhances morphological mitochondrial deterioration and degeneration of dopaminergic and non-dopaminergic neurons, but has no influence on neuronal network activity. Conversely, ß-Syn P123H silences neuronal network activity, but does not aggravate neurodegeneration. ß-Syn WT, V70M and P123H formed proteinase K (PK) resistant intracellular fibrils within neurons, albeit with less stable C-termini as compared to α-Syn. Under cell free conditions, ß-Syn V70M demonstrated a much slower pace of fibril formation as compared to WT ß-Syn, and P123H fibrils present with a unique phenotype characterized by large numbers of short, truncated fibrils. Thus, it is possible that V70M and P123H cause structural alterations in ß-Syn, that are linked to their distinct neuropathological profiles. The extent of the lesions caused by these neuropathological profiles is almost identical to that of overabundant α-Syn, and thus likely to be directly involved into etiology of DLB. Over all, this study provides insights into distinct disease mechanisms caused by mutations of ß-Syn.