1
|
Wang W, Sessler CD, Wang X, Liu J. In Situ Synthesis and Assembly of Functional Materials and Devices in Living Systems. Acc Chem Res 2024. [PMID: 39007720 DOI: 10.1021/acs.accounts.4c00049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
ConspectusIntegrating functional materials and devices with living systems enables novel methods for recording, manipulating, or augmenting organisms not accessible by traditional chemical, optical, or genetic approaches. (The term "device" refers to the fundamental components of complex electronic systems, such as transistors, capacitors, conductors, and electrodes.) Typically, these advanced materials and devices are synthesized, either through chemical or physical reactions, outside the biological systems (ex situ) before they are integrated. This is due in part to the more limited repertoire of biocompatible chemical transformations available for assembling functional materials in vivo. Given that most of the assembled bulk materials are impermeable to cell membranes and cannot go through the blood-brain barrier (BBB), the external synthesis poses challenges when trying to interface these materials and devices with cells precisely and in a timely manner and at the micro- and nanoscale─a crucial requirement for modulating cellular functions. In contrast to presynthesis in a separate location, in situ assembly, wherein small molecules or building blocks are directly assembled into functional materials within a biological system at the desired site of action, has offered a potential solution for spatiotemporal and genetic control of material synthesis and assembly.In this Account, we highlight recent advances in spatially and temporally targeted functional material synthesis and assembly in living cells, tissues and animals and provide perspective on how they may enable novel probing, modulation, or augmentation of fundamental biology. We discuss several strategies, starting from the traditional nontargeted methods to targeted assembly of functional materials and devices based on the endogenous markers of the biological system. We then focus on genetically targeted assembly of functional materials, which employs enzymatic catalysis centers expressed in living systems to assemble functional materials in specific molecular-defined cell types. We introduce the recent efforts of our group to modulate membrane capacitance and neuron excitability using in situ synthesized electrically functional polymers in a genetically targetable manner. These advances demonstrate the promise of in situ synthesis and assembly of functional materials and devices, including the optogenetic polymerization developed by our lab, to interface with cells in a cellular- or subcellular-specific manner by incorporating genetic and/or optical control over material assembly. Finally, we discuss remaining challenges, areas for improvement, potential applications to other biological systems, and novel methods for the in situ synthesis of functional materials that could be elevated by incorporating genetic or material design strategies. As researchers expand the toolkit of biocompatible in situ functional material synthetic techniques, we anticipate that these advancements could potentially offer valuable tools for exploring biological systems and developing therapeutic solutions.
Collapse
Affiliation(s)
- Wenbo Wang
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, Massachusetts 02134, United States
| | - Chanan D Sessler
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, United States
| | - Xiao Wang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, United States
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, United States
| | - Jia Liu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, Massachusetts 02134, United States
| |
Collapse
|
2
|
Yang Y, Tuo J, Zhang J, Xu Z, Luo Z. Pathogenic genes implicated in sleep-related hypermotor epilepsy: a research progress update. Front Neurol 2024; 15:1416648. [PMID: 38966089 PMCID: PMC11222571 DOI: 10.3389/fneur.2024.1416648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 06/11/2024] [Indexed: 07/06/2024] Open
Abstract
Sleep-related hypermotor epilepsy (SHE) is a focal epilepsy syndrome characterized by a variable age of onset and heterogeneous etiology. Current literature suggests a prevalence rate of approximately 1.8 per 100,000 persons. The discovery of additional pathogenic genes associated with SHE in recent years has significantly expanded the knowledge and understanding of its pathophysiological mechanisms. Identified SHE pathogenic genes include those related to neuronal ligand- and ion-gated channels (CHRNA4, CHRNB2, CHRNA2, GABRG2, and KCNT1), genes upstream of the mammalian target of rapamycin complex 1 signal transduction pathway (DEPDC5, NPRL2, NPRL3, TSC1, and TSC2), and other genes (CRH, CaBP4, STX1B, and PRIMA1). These genes encode proteins associated with ion channels, neurotransmitter receptors, cell signal transduction, and synaptic transmission. Mutations in these genes can result in the dysregulation of encoded cellular functional proteins and downstream neuronal dysfunction, ultimately leading to epileptic seizures. However, the associations between most genes and the SHE phenotype remain unclear. This article presents a literature review on the research progress of SHE-related pathogenic genes to contribute evidence to genotype-phenotype correlations in SHE and establish the necessary theoretical basis for future SHE treatments.
Collapse
Affiliation(s)
- Yufang Yang
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Jinmei Tuo
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
- Department of Nursing, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Jun Zhang
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Zucai Xu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Zhong Luo
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| |
Collapse
|
3
|
Shore AN, Li K, Safari M, Qunies AM, Spitznagel BD, Weaver CD, Emmitte KA, Frankel WN, Weston MC. Heterozygous expression of a Kcnt1 gain-of-function variant has differential effects on SST- and PV-expressing cortical GABAergic neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.11.561953. [PMID: 37873369 PMCID: PMC10592778 DOI: 10.1101/2023.10.11.561953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
More than twenty recurrent missense gain-of-function (GOF) mutations have been identified in the sodium-activated potassium (KNa) channel gene KCNT1 in patients with severe developmental and epileptic encephalopathies (DEEs), most of which are resistant to current therapies. Defining the neuron types most vulnerable to KCNT1 GOF will advance our understanding of disease mechanisms and provide refined targets for precision therapy efforts. Here, we assessed the effects of heterozygous expression of a Kcnt1 GOF variant (Y777H) on KNa currents and neuronal physiology among cortical glutamatergic and GABAergic neurons in mice, including those expressing vasoactive intestinal polypeptide (VIP), somatostatin (SST), and parvalbumin (PV), to identify and model the pathogenic mechanisms of autosomal dominant KCNT1 GOF variants in DEEs. Although the Kcnt1-Y777H variant had no effects on glutamatergic or VIP neuron function, it increased subthreshold KNa currents in both SST and PV neurons but with opposite effects on neuronal output; SST neurons became hypoexcitable with a higher rheobase current and lower action potential (AP) firing frequency, whereas PV neurons became hyperexcitable with a lower rheobase current and higher AP firing frequency. Further neurophysiological and computational modeling experiments showed that the differential effects of the Y777H variant on SST and PV neurons are not likely due to inherent differences in these neuron types, but to an increased persistent sodium current in PV, but not SST, neurons. The Y777H variant also increased excitatory input onto, and chemical and electrical synaptic connectivity between, SST neurons. Together, these data suggest differential pathogenic mechanisms, both direct and compensatory, contribute to disease phenotypes, and provide a salient example of how a pathogenic ion channel variant can cause opposite functional effects in closely related neuron subtypes due to interactions with other ionic conductances.
Collapse
Affiliation(s)
- Amy N. Shore
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
- Department of Neurological Sciences, University of Vermont, Burlington, VT, USA
| | - Keyong Li
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
| | - Mona Safari
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
- Translational Biology, Medicine, and Health Graduate Program, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA
| | - Alshaima’a M. Qunies
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX, USA
- School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Brittany D. Spitznagel
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Kyle A. Emmitte
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Wayne N. Frankel
- Institute for Genomic Medicine, Columbia University, New York, NY, USA
- Department of Neurology, Columbia University, New York, NY, USA
| | - Matthew C. Weston
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
- Department of Neurological Sciences, University of Vermont, Burlington, VT, USA
- Translational Biology, Medicine, and Health Graduate Program, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA
- School of Neuroscience, Virginia Tech, Blacksburg, VA, USA
| |
Collapse
|
4
|
Qunies AM, Spitznagel BD, Du Y, Peprah PK, Mohamed YK, Weaver CD, Emmitte KA. Structure-Activity Relationship Studies in a Series of Xanthine Inhibitors of SLACK Potassium Channels. Molecules 2024; 29:2437. [PMID: 38893312 PMCID: PMC11173529 DOI: 10.3390/molecules29112437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 05/17/2024] [Accepted: 05/20/2024] [Indexed: 06/21/2024] Open
Abstract
Gain-of-function mutations in the KCNT1 gene, which encodes the sodium-activated potassium channel known as SLACK, are associated with the rare but devastating developmental and epileptic encephalopathy known as epilepsy of infancy with migrating focal seizures (EIMFS). The design of small molecule inhibitors of SLACK channels represents a potential therapeutic approach to the treatment of EIMFS, other childhood epilepsies, and developmental disorders. Herein, we describe a hit optimization effort centered on a xanthine SLACK inhibitor (8) discovered via a high-throughput screen. Across three distinct regions of the chemotype, we synthesized 58 new analogs and tested each one in a whole-cell automated patch-clamp assay to develop structure-activity relationships for inhibition of SLACK channels. We further evaluated selected analogs for their selectivity versus a variety of other ion channels and for their activity versus clinically relevant SLACK mutants. Selectivity within the series was quite good, including versus hERG. Analog 80 (VU0948578) was a potent inhibitor of WT, A934T, and G288S SLACK, with IC50 values between 0.59 and 0.71 µM across these variants. VU0948578 represents a useful in vitro tool compound from a chemotype that is distinct from previously reported small molecule inhibitors of SLACK channels.
Collapse
Affiliation(s)
- Alshaima’a M. Qunies
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | | | - Yu Du
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Paul K. Peprah
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
- School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Yasmeen K. Mohamed
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
- Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Kyle A. Emmitte
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| |
Collapse
|
5
|
Dhureja M, Chaturvedi P, Choudhary A, Kumar P, Munshi A. Molecular Insights of Drug Resistance in Epilepsy: Multi-omics Unveil. Mol Neurobiol 2024:10.1007/s12035-024-04220-6. [PMID: 38753128 DOI: 10.1007/s12035-024-04220-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 05/03/2024] [Indexed: 06/12/2024]
Abstract
Epilepsy is a devastating neurological disorder mainly associated with impaired synchronic discharge that leads to sensory, motor, and psychomotor impairments. Till now, about 30 anti-seizure medications (ASMs) have been approved for the management of epilepsy, yet one-third of individuals still have uncontrollable epilepsy and develop resistance. Drug resistance epilepsy (DRE) is defined as the condition where two ASMs fail to control the seizure in epileptic patients. The leading cause of the resistance was the extended use of ASMs. According to various studies, alterations in some genes and their expressions, along with specific metabolic impairments, are suggested to be associated with ASMs resistance and DRE pathophysiology. Several factors aid in the pathophysiology of DRE, such as alterations in protein-encoding genes such as neurotransmitter receptors, drug transporters, ion channels, and drug targets. Furthermore, the altered metabolite levels of metabolites implicated in neurotransmitter signaling, energetic pathways, oxidative stress, and neuroinflammatory signaling differentiate the epileptic patient from the DRE patient. Various DRE biomarkers can be identified using the "integrated omics approach," which includes the study of genomics, transcriptomics, and metabolomics. The current review has been compiled to understand the pathophysiological mechanisms of DRE by focusing on genomics, transcriptomics, and metabolomics. An effort has also been made to identify the therapeutic targets based on identifying significant markers by a multi-omics approach. This has the potential to develop novel therapeutic interventions in the future.
Collapse
Affiliation(s)
- Maanvi Dhureja
- Department of Pharmacology, Central University of Punjab, Bathinda, India
| | - Pragya Chaturvedi
- Department of Human Genetics and Molecular Medicines, Central University of Punjab, Bathinda, India
| | - Anita Choudhary
- Department of Human Genetics and Molecular Medicines, Central University of Punjab, Bathinda, India
| | - Puneet Kumar
- Department of Pharmacology, Central University of Punjab, Bathinda, India.
| | - Anjana Munshi
- Department of Human Genetics and Molecular Medicines, Central University of Punjab, Bathinda, India.
| |
Collapse
|
6
|
Mosca I, Freri E, Ambrosino P, Belperio G, Granata T, Canafoglia L, Ragona F, Solazzi R, Filareto I, Castellotti B, Messina G, Gellera C, DiFrancesco JC, Soldovieri MV, Taglialatela M. Case report: Marked electroclinical improvement by fluoxetine treatment in a patient with KCNT1-related drug-resistant focal epilepsy. Front Cell Neurosci 2024; 18:1367838. [PMID: 38644974 PMCID: PMC11027738 DOI: 10.3389/fncel.2024.1367838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 03/11/2024] [Indexed: 04/23/2024] Open
Abstract
Variants in KCNT1 are associated with a wide spectrum of epileptic phenotypes, including epilepsy of infancy with migrating focal seizures (EIMFS), non-EIMFS developmental and epileptic encephalopathies, autosomal dominant or sporadic sleep-related hypermotor epilepsy, and focal epilepsy. Here, we describe a girl affected by drug-resistant focal seizures, developmental delay and behavior disorders, caused by a novel, de novo heterozygous missense KCNT1 variant (c.2809A > G, p.S937G). Functional characterization in transiently transfected Chinese Hamster Ovary (CHO) cells revealed a strong gain-of-function effect determined by the KCNT1 p.S937G variant compared to wild-type, consisting in an increased maximal current density and a hyperpolarizing shift in current activation threshold. Exposure to the antidepressant drug fluoxetine inhibited currents expressed by both wild-type and mutant KCNT1 channels. Treatment of the proband with fluoxetine led to a prolonged electroclinical amelioration, with disappearance of seizures and better EEG background organization, together with an improvement in behavior and mood. Altogether, these results suggest that, based on the proband's genetic and functional characteristics, the antidepressant drug fluoxetine may be repurposed for the treatment of focal epilepsy caused by gain-of-function variants in KCNT1. Further studies are needed to verify whether this approach could be also applied to other phenotypes of the KCNT1-related epilepsies spectrum.
Collapse
Affiliation(s)
- Ilaria Mosca
- Department of Medicine and Health Sciences “Vincenzo Tiberio”, University of Molise, Campobasso, Italy
| | - Elena Freri
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Paolo Ambrosino
- Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Giorgio Belperio
- Department of Science and Technology, University of Sannio, Benevento, Italy
| | - Tiziana Granata
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Laura Canafoglia
- Department of Diagnostic and Technology, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Francesca Ragona
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Roberta Solazzi
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Ilaria Filareto
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Barbara Castellotti
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy
| | - Giuliana Messina
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy
| | - Cinzia Gellera
- Unit of Medical Genetics and Neurogenetics, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy
| | | | - Maria Virginia Soldovieri
- Department of Medicine and Health Sciences “Vincenzo Tiberio”, University of Molise, Campobasso, Italy
| | | |
Collapse
|
7
|
Wu J, Quraishi IH, Zhang Y, Bromwich M, Kaczmarek LK. Disease-causing Slack potassium channel mutations produce opposite effects on excitability of excitatory and inhibitory neurons. Cell Rep 2024; 43:113904. [PMID: 38457342 PMCID: PMC11013952 DOI: 10.1016/j.celrep.2024.113904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 12/18/2023] [Accepted: 02/16/2024] [Indexed: 03/10/2024] Open
Abstract
The KCNT1 gene encodes the sodium-activated potassium channel Slack (KCNT1, KNa1.1), a regulator of neuronal excitability. Gain-of-function mutations in humans cause cortical network hyperexcitability, seizures, and severe intellectual disability. Using a mouse model expressing the Slack-R455H mutation, we find that Na+-dependent K+ (KNa) and voltage-dependent sodium (NaV) currents are increased in both excitatory and inhibitory cortical neurons. These increased currents, however, enhance the firing of excitability neurons but suppress that of inhibitory neurons. We further show that the expression of NaV channel subunits, particularly that of NaV1.6, is upregulated and that the length of the axon initial segment and of axonal NaV immunostaining is increased in both neuron types. Our study on the coordinate regulation of KNa currents and the expression of NaV channels may provide an avenue for understanding and treating epilepsies and other neurological disorders.
Collapse
Affiliation(s)
- Jing Wu
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Imran H Quraishi
- Department of Neurology, Yale Comprehensive Epilepsy Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Yalan Zhang
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Mark Bromwich
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Leonard K Kaczmarek
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06520, USA; Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT 06520, USA.
| |
Collapse
|
8
|
Hussain R, Lim CX, Shaukat Z, Islam A, Caseley EA, Lippiat JD, Rychkov GY, Ricos MG, Dibbens LM. Drosophila expressing mutant human KCNT1 transgenes make an effective tool for targeted drug screening in a whole animal model of KCNT1-epilepsy. Sci Rep 2024; 14:3357. [PMID: 38336906 PMCID: PMC10858247 DOI: 10.1038/s41598-024-53588-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 02/01/2024] [Indexed: 02/12/2024] Open
Abstract
Mutations in the KCNT1 potassium channel cause severe forms of epilepsy which are poorly controlled with current treatments. In vitro studies have shown that KCNT1-epilepsy mutations are gain of function, significantly increasing K+ current amplitudes. To investigate if Drosophila can be used to model human KCNT1 epilepsy, we generated Drosophila melanogaster lines carrying human KCNT1 with the patient mutation G288S, R398Q or R928C. Expression of each mutant channel in GABAergic neurons gave a seizure phenotype which responded either positively or negatively to 5 frontline epilepsy drugs most commonly administered to patients with KCNT1-epilepsy, often with little or no improvement of seizures. Cannabidiol showed the greatest reduction of the seizure phenotype while some drugs increased the seizure phenotype. Our study shows that Drosophila has the potential to model human KCNT1- epilepsy and can be used as a tool to assess new treatments for KCNT1- epilepsy.
Collapse
Affiliation(s)
- Rashid Hussain
- Epilepsy Research Group, Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA, 5000, Australia
| | - Chiao Xin Lim
- Epilepsy Research Group, Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA, 5000, Australia
- Pharmacy, School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC, 3083, Australia
| | - Zeeshan Shaukat
- Epilepsy Research Group, Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA, 5000, Australia
| | - Anowarul Islam
- Epilepsy Research Group, Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA, 5000, Australia
- College of Medicine and Public Health, Flinders University, Bedford Park, SA, 5042, Australia
| | - Emily A Caseley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Jonathan D Lippiat
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Grigori Y Rychkov
- Epilepsy Research Group, Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA, 5000, Australia
- School of Biomedicine, University of Adelaide, Adelaide, SA, 5005, Australia
- South Australian Health and Medical Research Institute, Adelaide, SA, 5005, Australia
| | - Michael G Ricos
- Epilepsy Research Group, Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA, 5000, Australia
| | - Leanne M Dibbens
- Epilepsy Research Group, Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA, 5000, Australia.
| |
Collapse
|
9
|
Liu R, Sun L, Shi X, Li C, Guo X, Wang Y, Wang X, Zhang K, Wang Y, Wang Q, Wu J. Increased Expression of K Na1.2 Channel by MAPK Pathway Regulates Neuronal Activity Following Traumatic Brain Injury. Neurochem Res 2024; 49:427-440. [PMID: 37875713 DOI: 10.1007/s11064-023-04044-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 10/02/2023] [Accepted: 10/04/2023] [Indexed: 10/26/2023]
Abstract
Recent studies have indicated that functional abnormalities in the KNa1.2 channel are linked to epileptic encephalopathies. However, the role of KNa1.2 channel in traumatic brain injury (TBI) remains limited. We collected brain tissue from the TBI mice and patients with post-traumatic epilepsy (PTE) to determine changes in KNa1.2 channel following TBI. We also investigated whether the MAPK pathway, which was activated by the released cytokines after injury, regulated KNa1.2 channel in in vitro. Finally, to elucidate the physiological significance of KNa1.2 channel in neuronal excitability, we utilized the null mutant-Kcnt2-/- mice and compared their behavior patterns, seizure susceptibility, and neuronal firing properties to wild type (WT) mice. TBI was induced in both Kcnt2-/- and WT mice to investigate any differences between the two groups under pathological condition. Our findings revealed that the expression of KNa1.2 channel was notably increased only during the acute phase following TBI, while no significant elevation was observed during the late phase. Furthermore, we identified the released cytokines and activated MAPK pathway in the neurons after TBI and confirmed that KNa1.2 channel was enhanced by the MAPK pathway via stimulation of TNF-α. Subsequently, compared to WT mice, neurons from Kcnt2-/- mice showed increased neuronal excitability and Kcnt2-/- mice displayed motor deficits and enhanced seizure susceptibility, which suggested that KNa1.2 channel may be neuroprotective. Therefore, this study suggests that enhanced KNa1.2 channel, facilitated by the inflammatory response, may exert a protective role in an acute phase of the TBI model.
Collapse
Affiliation(s)
- Ru Liu
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
| | - Lei Sun
- Department of Neurology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, 450008, Henan, China
| | - Xiaorui Shi
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
| | - Ci Li
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China
| | - Xi Guo
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
| | - Yingting Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
| | - Xiu Wang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
| | - Kai Zhang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
| | - Yongjun Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
| | - Qun Wang
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
- Beijing Institute for Brain Disorders, Beijing, 100070, China
| | - Jianping Wu
- Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China.
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China.
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China.
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070, Hubei, China.
| |
Collapse
|
10
|
Martini L, Amprimo G, Di Carlo S, Olmo G, Ferraris C, Savino A, Bardini R. Neuronal Spike Shapes (NSS): A straightforward approach to investigate heterogeneity in neuronal excitability states. Comput Biol Med 2024; 168:107783. [PMID: 38056213 DOI: 10.1016/j.compbiomed.2023.107783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 10/23/2023] [Accepted: 11/28/2023] [Indexed: 12/08/2023]
Abstract
The mammalian brain exhibits a remarkable diversity of neurons, contributing to its intricate architecture and functional complexity. The analysis of multimodal single-cell datasets enables the investigation of cell types and states heterogeneity. In this study, we introduce the Neuronal Spike Shapes (NSS), a straightforward approach for the exploration of excitability states of neurons based on their Action Potential (AP) waveforms. The NSS method describes the AP waveform based on a triangular representation complemented by a set of derived electrophysiological (EP) features. To support this hypothesis, we validate the proposed approach on two datasets of murine cortical neurons, focusing it on GABAergic neurons. The validation process involves a combination of NSS-based clustering analysis, features exploration, Differential Expression (DE), and Gene Ontology (GO) enrichment analysis. Results show that the NSS-based analysis captures neuronal excitability states that possess biological relevance independently of cell subtype. In particular, Neuronal Spike Shapes (NSS) captures, among others, a well-characterized fast-spiking excitability state, supported by both electrophysiological and transcriptomic validation. Gene Ontology Enrichment Analysis reveals voltage-gated potassium (K+) channels as specific markers of the identified NSS partitions. This finding strongly corroborates the biological relevance of NSS partitions as excitability states, as the expression of voltage-gated K+ channels regulates the hyperpolarization phase of the AP, being directly implicated in the regulation of neuronal excitability.
Collapse
Affiliation(s)
- Lorenzo Martini
- Politecnico di Torino - Control and Computer Engineering Department, Corso Duca degli Abruzzi, 24, Turin, 10129, Italy.
| | - Gianluca Amprimo
- Politecnico di Torino - Control and Computer Engineering Department, Corso Duca degli Abruzzi, 24, Turin, 10129, Italy; Institute of Electronics, Information Engineering and Telecommunications, National Research Council, Corso Duca degli Abruzzi, 24, Turin, 10029, Italy.
| | - Stefano Di Carlo
- Politecnico di Torino - Control and Computer Engineering Department, Corso Duca degli Abruzzi, 24, Turin, 10129, Italy. https://www.smilies.polito.it
| | - Gabriella Olmo
- Politecnico di Torino - Control and Computer Engineering Department, Corso Duca degli Abruzzi, 24, Turin, 10129, Italy. https://www.sysbio.polito.it/analytics-technologies-health/
| | - Claudia Ferraris
- Institute of Electronics, Information Engineering and Telecommunications, National Research Council, Corso Duca degli Abruzzi, 24, Turin, 10029, Italy. https://www.ieiit.cnr.it/people/Ferraris-Claudia
| | - Alessandro Savino
- Politecnico di Torino - Control and Computer Engineering Department, Corso Duca degli Abruzzi, 24, Turin, 10129, Italy. https://www.smilies.polito.it
| | - Roberta Bardini
- Politecnico di Torino - Control and Computer Engineering Department, Corso Duca degli Abruzzi, 24, Turin, 10129, Italy.
| |
Collapse
|
11
|
Sands TT, Gelinas JN. Epilepsy and Encephalopathy. Pediatr Neurol 2024; 150:24-31. [PMID: 37948790 DOI: 10.1016/j.pediatrneurol.2023.09.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 09/14/2023] [Accepted: 09/24/2023] [Indexed: 11/12/2023]
Abstract
BACKGROUND Epilepsy encompasses more than the predisposition to unprovoked seizures. In children, epileptic activity during (ictal) and between (interictal) seizures has the potential to disrupt normal brain development. The term "epileptic encephalopathy (EE)" refers to the concept that such abnormal activity may contribute to cognitive and behavioral impairments beyond that expected from the underlying cause of the epileptic activity. METHODS In this review, we survey the concept of EE across a diverse selection of syndromes to illustrate its broad applicability in pediatric epilepsy. We review experimental evidence that provides mechanistic insights into how epileptic activity has the potential to impact normal brain processes and the development of neural networks. We then discuss opportunities to improve developmental outcomes in epilepsy now and in the future. RESULTS Epileptic activity in the brain poses a threat to normal physiology and brain development. CONCLUSION Until we have treatments that reliably target and effectively treat the underlying causes of epilepsy, a major goal of management is to prevent epileptic activity from worsening developmental outcomes.
Collapse
Affiliation(s)
- Tristan T Sands
- Center for Translational Research in Neurodevelopmental Disease, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; Departments of Neurology and Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York.
| | - Jennifer N Gelinas
- Center for Translational Research in Neurodevelopmental Disease, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; Departments of Neurology and Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York
| |
Collapse
|
12
|
Kulkarni S, Saha M, Slosberg J, Singh A, Nagaraj S, Becker L, Zhang C, Bukowski A, Wang Z, Liu G, Leser JM, Kumar M, Bakhshi S, Anderson MJ, Lewandoski M, Vincent E, Goff LA, Pasricha PJ. Age-associated changes in lineage composition of the enteric nervous system regulate gut health and disease. eLife 2023; 12:RP88051. [PMID: 38108810 PMCID: PMC10727506 DOI: 10.7554/elife.88051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023] Open
Abstract
The enteric nervous system (ENS), a collection of neural cells contained in the wall of the gut, is of fundamental importance to gastrointestinal and systemic health. According to the prevailing paradigm, the ENS arises from progenitor cells migrating from the neural crest and remains largely unchanged thereafter. Here, we show that the lineage composition of maturing ENS changes with time, with a decline in the canonical lineage of neural-crest derived neurons and their replacement by a newly identified lineage of mesoderm-derived neurons. Single cell transcriptomics and immunochemical approaches establish a distinct expression profile of mesoderm-derived neurons. The dynamic balance between the proportions of neurons from these two different lineages in the post-natal gut is dependent on the availability of their respective trophic signals, GDNF-RET and HGF-MET. With increasing age, the mesoderm-derived neurons become the dominant form of neurons in the ENS, a change associated with significant functional effects on intestinal motility which can be reversed by GDNF supplementation. Transcriptomic analyses of human gut tissues show reduced GDNF-RET signaling in patients with intestinal dysmotility which is associated with reduction in neural crest-derived neuronal markers and concomitant increase in transcriptional patterns specific to mesoderm-derived neurons. Normal intestinal function in the adult gastrointestinal tract therefore appears to require an optimal balance between these two distinct lineages within the ENS.
Collapse
Affiliation(s)
- Subhash Kulkarni
- Division of Gastroenterology, Dept of Medicine, Beth Israel Deaconess Medical CenterBostonUnited States
- Division of Medical Sciences, Harvard Medical SchoolBostonUnited States
| | - Monalee Saha
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Jared Slosberg
- Department of Genetic Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Alpana Singh
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Sushma Nagaraj
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Laren Becker
- Division of Gastroenterology, Stanford University – School of MedicineStanfordUnited States
| | - Chengxiu Zhang
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Alicia Bukowski
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Zhuolun Wang
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Guosheng Liu
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Jenna M Leser
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Mithra Kumar
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Shriya Bakhshi
- Center for Neurogastroenterology, Department of Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Matthew J Anderson
- Center for Cancer Research, National Cancer InstituteFrederickUnited States
| | - Mark Lewandoski
- Center for Cancer Research, National Cancer InstituteFrederickUnited States
| | - Elizabeth Vincent
- Department of Genetic Medicine, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | - Loyal A Goff
- Department of Neuroscience, Johns Hopkins University – School of MedicineBaltimoreUnited States
- Kavli Neurodiscovery Institute, Johns Hopkins University – School of MedicineBaltimoreUnited States
| | | |
Collapse
|
13
|
Manning A, Han V, Stephens A, Wang R, Bush N, Bard M, Ramirez JM, Kalume F. Elevated susceptibility to exogenous seizure triggers and impaired interneuron excitability in a mouse model of Leigh syndrome epilepsy. Neurobiol Dis 2023; 187:106288. [PMID: 37704057 PMCID: PMC10621616 DOI: 10.1016/j.nbd.2023.106288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 08/12/2023] [Accepted: 09/10/2023] [Indexed: 09/15/2023] Open
Abstract
Mutations in the NADH dehydrogenase (ubiquinone reductase) iron‑sulfur protein 4 (NDUFS4) gene, which encodes for a key structural subunit of the OXFOS complex I (CI), lead to the most common form of mitochondrial disease in children known as Leigh syndrome (LS). As in other mitochondrial diseases, epileptic seizures constitute one of the most significant clinical features of LS. These seizures are often very difficult to treat and are a sign of poor disease prognosis. Mice with whole-body Ndufs4 KO are a well-validated model of LS; they exhibit epilepsy and several other clinical features of LS. We have previously shown that mice with Ndufs4 KO in only GABAergic interneurons (Gad2-Ndufs4-KO) reproduce the severe epilepsy phenotype observed in the global KO mice. This observation indicated that these mice represent an excellent model of LS epilepsy isolated from other clinical manifestations of the disease. To further characterize this epilepsy phenotype, we investigated seizure susceptibility to selected exogenous seizure triggers in Gad2-Ndufs4-KO mice. Then, using electrophysiology, imaging, and immunohistochemistry, we studied the cellular, physiological, and neuroanatomical consequences of Ndufs4 KO in GABAergic interneurons. Homozygous KO of Ndufs4 in GABAergic interneurons leads to a prominent susceptibility to exogenous seizure triggers, impaired interneuron excitability and interneuron loss. Finally, we found that the hippocampus and cortex participate in the generation of seizure activity in Gad2-Ndufs4-KO mice. These findings further define the LS epilepsy phenotype and provide important insights into the cellular mechanisms underlying epilepsy in LS and other mitochondrial diseases.
Collapse
Affiliation(s)
- Arena Manning
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States of America; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America
| | - Victor Han
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America
| | - Alexa Stephens
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America
| | - Rose Wang
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America
| | - Nicholas Bush
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America
| | - Michelle Bard
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America
| | - Jan M Ramirez
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States of America; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America; Department of Neurological Surgery, University of Washington, Seattle, WA, United States of America
| | - Franck Kalume
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, United States of America; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States of America; Department of Neurological Surgery, University of Washington, Seattle, WA, United States of America.
| |
Collapse
|
14
|
Hill SF, Jafar-Nejad P, Rigo F, Meisler MH. Reduction of Kcnt1 is therapeutic in mouse models of SCN1A and SCN8A epilepsy. Front Neurosci 2023; 17:1282201. [PMID: 37901435 PMCID: PMC10603267 DOI: 10.3389/fnins.2023.1282201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 09/25/2023] [Indexed: 10/31/2023] Open
Abstract
Developmental and epileptic encephalopathies (DEEs) are severe seizure disorders with inadequate treatment options. Gain- or loss-of-function mutations of neuronal ion channel genes, including potassium channels and voltage-gated sodium channels, are common causes of DEE. We previously demonstrated that reduced expression of the sodium channel gene Scn8a is therapeutic in mouse models of sodium and potassium channel mutations. In the current study, we tested whether reducing expression of the potassium channel gene Kcnt1 would be therapeutic in mice with mutation of the sodium channel genes Scn1a or Scn8a. A Kcnt1 antisense oligonucleotide (ASO) prolonged survival of both Scn1a and Scn8a mutant mice, suggesting a modulatory effect for KCNT1 on the balance between excitation and inhibition. The cation channel blocker quinidine was not effective in prolonging survival of the Scn8a mutant. Our results implicate KCNT1 as a therapeutic target for treatment of SCN1A and SCN8A epilepsy.
Collapse
Affiliation(s)
- Sophie F. Hill
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, United States
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States
| | | | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, CA, United States
| | - Miriam H. Meisler
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, United States
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| |
Collapse
|
15
|
Skrabak D, Bischof H, Pham T, Ruth P, Ehinger R, Matt L, Lukowski R. Slack K + channels limit kainic acid-induced seizure severity in mice by modulating neuronal excitability and firing. Commun Biol 2023; 6:1029. [PMID: 37821582 PMCID: PMC10567740 DOI: 10.1038/s42003-023-05387-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 09/25/2023] [Indexed: 10/13/2023] Open
Abstract
Mutations of the Na+-activated K+ channel Slack (KCNT1) are associated with terrible epilepsy syndromes that already begin in infancy. Here we report increased severity of acute kainic acid-induced seizures in adult and juvenile Slack knockout mice (Slack-/-) in vivo. Fittingly, we find exacerbation of cell death following kainic acid exposure in organotypic hippocampal slices as well as dissociated hippocampal cultures from Slack-/- in vitro. Furthermore, in cultured Slack-/- neurons, kainic acid-triggered Ca2+ influx and K+ efflux as well as depolarization-induced tetrodotoxin-sensitive inward currents are higher compared to the respective controls. This apparent changes in ion homeostasis could possibly explain altered action potential kinetics of Slack-/- neurons: steeper rise slope, decreased threshold, and duration of afterhyperpolarization, which ultimately lead to higher action potential frequencies during kainic acid application or injection of depolarizing currents. Based on our data, we propose Slack as crucial gatekeeper of neuronal excitability to acutely limit seizure severity.
Collapse
Affiliation(s)
- David Skrabak
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Helmut Bischof
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Thomas Pham
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Peter Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Rebekka Ehinger
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Lucas Matt
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Robert Lukowski
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany.
| |
Collapse
|
16
|
Hinckley CA, Zhu Z, Chu JH, Gubbels C, Danker T, Cherry JJ, Whelan CD, Engle SJ, Nguyen V. Functional evaluation of epilepsy-associated KCNT1 variants in multiple cellular systems reveals a predominant gain of function impact on channel properties. Epilepsia 2023; 64:2126-2136. [PMID: 37177976 DOI: 10.1111/epi.17648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/11/2023] [Accepted: 05/11/2023] [Indexed: 05/15/2023]
Abstract
OBJECTIVE Gain of function variants in the sodium-activated potassium channel KCNT1 have been associated with pediatric epilepsy disorders. Here, we systematically examine a spectrum of KCNT1 variants and establish their impact on channel function in multiple cellular systems. METHODS KCNT1 variants identified from published reports and genetic screening of pediatric epilepsy patients were expressed in Xenopus oocytes and HEK cell lines. Variant impact on current magnitude, current-voltage relationships, and sodium ion modulation were examined. RESULTS We determined basic properties of KCNT1 in Xenopus oocyte and HEK systems, including the role of extra- and intracellular sodium in regulating KCNT1 activity. The most common six KCNT1 variants demonstrated strong gain of function (GOF) effects on one or more channel properties. Analysis of 36 total variants identified phenotypic heterogeneity but a strong tendency for pathogenic variants to exert GOF effects on channel properties. By controlling intracellular sodium, we demonstrate that multiple pathogenic KCNT1 variants modulate channel voltage dependence by altering the sensitivity to sodium ions. SIGNIFICANCE This study represents the largest systematic functional examination of KCNT1 variants to date. We both confirm previously reported GOF channel phenotypes and expand the number of variants with in vitro GOF effects. Our data provide further evidence that novel KCNT1 variants identified in epilepsy patients lead to disease through generalizable GOF mechanisms including increases in current magnitude and/or current-voltage relationships.
Collapse
Affiliation(s)
| | | | | | | | - Timm Danker
- NMI Technologietransfer GmbH, Reutlingen, Germany
| | | | | | | | | |
Collapse
|
17
|
Tobin WF, Weston MC. Distinct Features of Interictal Activity Predict Seizure Localization and Burden in a Mouse Model of Childhood Epilepsy. J Neurosci 2023; 43:5076-5091. [PMID: 37290938 PMCID: PMC10324994 DOI: 10.1523/jneurosci.2205-22.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 05/24/2023] [Accepted: 06/05/2023] [Indexed: 06/10/2023] Open
Abstract
The epileptic brain is distinguished by spontaneous seizures and interictal epileptiform discharges (IEDs). Basic patterns of mesoscale brain activity outside of seizures and IEDs are also frequently disrupted in the epileptic brain and likely influence disease symptoms, but are poorly understood. We aimed to quantify how interictal brain activity differs from that in healthy individuals, and identify what features of interictal activity influence seizure occurrence in a genetic mouse model of childhood epilepsy. Neural activity across the majority of the dorsal cortex was monitored with widefield Ca2+ imaging in mice of both sexes expressing a human Kcnt1 variant (Kcnt1m/m ) and wild-type controls (WT). Ca2+ signals during seizures and interictal periods were classified according to their spatiotemporal features. We identified 52 spontaneous seizures, which emerged and propagated within a consistent set of susceptible cortical areas, and were predicted by a concentration of total cortical activity within the emergence zone. Outside of seizures and IEDs, similar events were detected in Kcnt1m/m and WT mice, suggesting that the spatial structure of interictal activity is similar. However, the rate of events whose spatial profile overlapped with where seizures and IEDs emerged was increased, and the characteristic global intensity of cortical activity in individual Kcnt1m/m mice predicted their epileptic activity burden. This suggests that cortical areas with excessive interictal activity are vulnerable to seizures, but epilepsy is not an inevitable outcome. Global scaling of the intensity of cortical activity below levels found in the healthy brain may provide a natural mechanism of seizure protection.SIGNIFICANCE STATEMENT Defining the scope and structure of an epilepsy-causing gene variant's effects on mesoscale brain activity constitutes a major contribution to our understanding of how epileptic brains differ from healthy brains, and informs the development of precision epilepsy therapies. We provide a clear roadmap for measuring how severely brain activity deviates from normal, not only in pathologically active areas, but across large portions of the brain and outside of epileptic activity. This will indicate where and how activity needs to be modulated to holistically restore normal function. It also has the potential to reveal unintended off-target treatment effects and facilitate therapy optimization to deliver maximal benefit with minimal side-effect potential.
Collapse
Affiliation(s)
- William F Tobin
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405
| | - Matthew C Weston
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405
- Fralin Biomedical Research Institute and School of Neuroscience, Virginia Polytechnic and State University, Roanoke, VA 24016
| |
Collapse
|
18
|
Liu R, Sun L, Wang Y, Wang Q, Wu J. New use for an old drug: quinidine in KCNT1-related epilepsy therapy. Neurol Sci 2023; 44:1201-1206. [PMID: 36437393 DOI: 10.1007/s10072-022-06521-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 11/18/2022] [Indexed: 11/29/2022]
Abstract
KCNT1 has been known to encode a subunit of the tetrameric sodium activated potassium channel (KNa1.1). Pathogenic variants of KCNT1, especially gain-of-function (GOF) variants, are associated with multiple epileptic disorders which are often refractory to conventional anti-seizure medications and summarized as KCNT1-related epilepsy. Although the detailed pathogenic mechanisms of KCNT1-related epilepsy remain unknown, increasing studies attempt to find effective medications for those patients by utilizing quinidine to inhibit hyperexcitable KNa1.1. However, it has been shown that controversial outcomes among studies and partial success in some individuals may be due to multiple factors, such as poor blood-brain barrier (BBB) penetration, mutation-dependent manner, phenotype-genotype associations, and rational therapeutic schedule. In recent years, with higher resolution of KNa1.1 structure in different activation states and advanced synthetic techniques, it improves the process performance of therapy targeting at KNa1.1 channel to achieve more effective outcomes. Here, we systematically reviewed the study history of quinidine on KCNT1-related epilepsy and its corresponding therapeutic effects. Then, we analyzed and summarized the possible causes behind the different outcomes of the application of quinidine. Finally, we outlooked the recent advances in precision medicine treatment for KCNT1-related epilepsy.
Collapse
Affiliation(s)
- Ru Liu
- Hubei Key Laboratory of Nanomedicine for Neurodegenerative Diseases, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Loushi Rd, Wuhan, 430070, China
- Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
| | - Lei Sun
- Department of Neurology, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Henan University People's Hospital, Zhengzhou, 450008, Henan, China
| | - Yunfu Wang
- Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan, 442000, China
| | - Qun Wang
- Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China
| | - Jianping Wu
- Hubei Key Laboratory of Nanomedicine for Neurodegenerative Diseases, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Loushi Rd, Wuhan, 430070, China.
- Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China.
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China.
- China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China.
| |
Collapse
|
19
|
Wu J, Quraishi IH, Zhang Y, Bromwich M, Kaczmarek LK. Disease-causing Slack potassium channel mutations produce opposite effects on excitability of excitatory and inhibitory neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.14.528229. [PMID: 36824888 PMCID: PMC9948954 DOI: 10.1101/2023.02.14.528229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
KCNT1 encodes the sodium-activated potassium channel Slack (KCNT1, K Na 1.1), an important mediator of neuronal membrane excitability. Gain-of-function (GOF) mutations in humans lead cortical network hyperexcitability and seizures, as well as very severe intellectual disability. Using a mouse model of Slack GOF-associated epilepsy, we found that both excitatory and inhibitory neurons of the cerebral cortex have increased Na + -dependent K + (K Na ) currents and voltage-dependent sodium (Na V ) currents. The characteristics of the increased K Na currents were, however, different in the two cell types such that the intrinsic excitability of excitatory neurons was enhanced but that of inhibitory neurons was suppressed. We further showed that the expression of Na V channel subunits, particularly that of Na V 1.6, is upregulated and that the length of the axon initial segment (AIS) and of axonal Na V immunostaining is increased in both neuron types. We found that the proximity of the AIS to the soma is shorter in excitatory neurons than in inhibitory neurons of the mutant animals, potentially contributing to the different effects on membrane excitability. Our study on the coordinate regulation of K Na currents and the expression of Na V channels may provide a new avenue for understanding and treating epilepsies and other neurological disorders. In brief In a genetic mouse model of Na + -activated K + potassium channel gene Slack -related childhood epilepsy, Wu et al . show that a disease-causing gain-of-function (GOF) mutation R455H in Slack channel causes opposite effects on excitability of cortical excitatory and inhibitory neurons. In contrast to heterologous expression systems, they find that the increase in potassium current substantially alters the expression of sodium channel subunits, resulting in increased lengths of axonal initial segments. Highlights GOF mutations in Slack potassium channel cause elevated outward K + currents and inward voltage-dependent Na + (Na V ) currents in cortical neurons Slack GOF does not alter the expression of Slack channel but upregulates the expression of Na V channel Slack GOF enhances the excitability of excitatory neurons but suppresses the firing of inhibitory interneuronsSlack GOF alters the length of AIS in both excitatory and inhibitory neuronsProximity of AIS to the soma is different between excitatory neuron and inhibitory neuron.
Collapse
|
20
|
Rychkov GY, Shaukat Z, Lim CX, Hussain R, Roberts BJ, Bonardi CM, Rubboli G, Meaney BF, Whitney R, Møller RS, Ricos MG, Dibbens LM. Functional Effects of Epilepsy Associated KCNT1 Mutations Suggest Pathogenesis via Aberrant Inhibitory Neuronal Activity. Int J Mol Sci 2022; 23:ijms232315133. [PMID: 36499459 PMCID: PMC9740882 DOI: 10.3390/ijms232315133] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 11/28/2022] [Accepted: 11/29/2022] [Indexed: 12/05/2022] Open
Abstract
KCNT1 (K+ channel subfamily T member 1) is a sodium-activated potassium channel highly expressed in the nervous system which regulates neuronal excitability by contributing to the resting membrane potential and hyperpolarisation following a train of action potentials. Gain of function mutations in the KCNT1 gene are the cause of neurological disorders associated with different forms of epilepsy. To gain insights into the underlying pathobiology we investigated the functional effects of 9 recently published KCNT1 mutations, 4 previously studied KCNT1 mutations, and one previously unpublished KCNT1 variant of unknown significance. We analysed the properties of KCNT1 potassium currents and attempted to find a correlation between the changes in KCNT1 characteristics due to the mutations and severity of the neurological disorder they cause. KCNT1 mutations identified in patients with epilepsy were introduced into the full length human KCNT1 cDNA using quick-change site-directed mutagenesis protocol. Electrophysiological properties of different KCNT1 constructs were investigated using a heterologous expression system (HEK293T cells) and patch clamping. All mutations studied, except T314A, increased the amplitude of KCNT1 currents, and some mutations shifted the voltage dependence of KCNT1 open probability, increasing the proportion of channels open at the resting membrane potential. The T314A mutation did not affect KCNT1 current amplitude but abolished its voltage dependence. We observed a positive correlation between the severity of the neurological disorder and the KCNT1 channel open probability at resting membrane potential. This suggests that gain of function KCNT1 mutations cause epilepsy by increasing resting potassium conductance and suppressing the activity of inhibitory neurons. A reduction in action potential firing in inhibitory neurons due to excessively high resting potassium conductance leads to disinhibition of neural circuits, hyperexcitability and seizures.
Collapse
Affiliation(s)
- Grigori Y. Rychkov
- Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA 5000, Australia
- School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia
- South Australian Health and Medical Research Institute, Adelaide, SA 5005, Australia
- Correspondence:
| | - Zeeshan Shaukat
- Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA 5000, Australia
| | - Chiao Xin Lim
- Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA 5000, Australia
| | - Rashid Hussain
- Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA 5000, Australia
| | - Ben J. Roberts
- Clinical and Health Sciences, Health and Biomedical Innovation, University of South Australia, Adelaide, SA 5000, Australia
| | - Claudia M. Bonardi
- Department of Woman’s and Child’s Health, Padua University Hospital, 35128 Padua, Italy
- The Danish Epilepsy Centre, 4293 Dianalund, Denmark
| | - Guido Rubboli
- Denmark Department of Clinical Medicine, Copenhagen University Hospital, 2200 Copenhagen, Denmark
| | - Brandon F. Meaney
- Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON 8SL 4L8, Canada
| | - Robyn Whitney
- Division of Neurology, Department of Paediatrics, McMaster University, Hamilton, ON 8SL 4L8, Canada
| | - Rikke S. Møller
- Department of Epilepsy Genetics and Personalized Treatment, Member of the ERN EpiCARE, The Danish Epilepsy Centre, 4293 Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, 5000 Odense, Denmark
| | - Michael G. Ricos
- Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA 5000, Australia
| | - Leanne M. Dibbens
- Clinical and Health Sciences, Australian Centre for Precision Health, University of South Australia, Adelaide, SA 5000, Australia
| |
Collapse
|
21
|
Miziak B, Czuczwar SJ. Approaches for the discovery of drugs that target K Na 1.1 channels in KCNT1-associated epilepsy. Expert Opin Drug Discov 2022; 17:1313-1328. [PMID: 36408599 DOI: 10.1080/17460441.2023.2150164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
INTRODUCTION There are approximately 70 million people with epilepsy and about 30% of patients are not satisfactorily treated. A link between gene mutations and epilepsy is well documented. A number of pathological variants of KCNT1 gene (encoding the weakly voltage-dependent sodium-activated potassium channel - KNa 1.1) mutations has been found. For instance, epilepsy of infancy with migrating focal seizures, autosomal sleep-related hypermotor epilepsy or Ohtahara syndrome have been associated with KCNT1 gene mutations. AREAS COVERED Several methods for studies on KNa 1.1 channels have been reviewed - patch clamp analysis, Förster resonance energy transfer spectroscopy and whole-exome sequencing. The authors also review available drugs for the management of KCNT1 epilepsies. EXPERT OPINION The current methods enable deeper insights into electrophysiology of KNa 1.1 channels or its functioning in different activation states. It is also possible to identify a given KCNT1 mutation. Quinidine and cannabidiol show variable efficacy as add-on to baseline antiepileptic drugs so more effective treatments are required. A combined approach with the methods shown above, in silico methods and the animal model of KCNT1 epilepsies seems likely to create personalized treatment of patients with KCNT1 gene mutations.
Collapse
Affiliation(s)
- Barbara Miziak
- Department of Pathophysiology, Medical University of Lublin, Lublin, Poland
| | | |
Collapse
|
22
|
Li X, Zhou L, Zhang X, Jin Y, Zhao B, Zhang D, Xi C, Ruan J, Zhu Z, Jia JM. Proteins secreted by brain arteriolar smooth muscle cells are instructive for neural development. Mol Brain 2022; 15:97. [PMID: 36451193 PMCID: PMC9710182 DOI: 10.1186/s13041-022-00983-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 11/17/2022] [Indexed: 12/12/2022] Open
Abstract
Intercellular communication between vascular and nerve cells mediated by diffusible proteins has recently emerged as a critical intrinsic program for neural development. However, whether the vascular smooth muscle cell (VSMC) secretome regulates the connectivity of neural circuits remains unknown. Here, we show that conditioned medium from brain VSMC cultures enhances multiple neuronal functions, such as neuritogenesis, neuronal maturation, and survival, thereby improving circuit connectivity. However, protein denaturation by heating compromised these effects. Combined omics analyses of donor VSMC secretomes and recipient neuron transcriptomes revealed that overlapping pathways of extracellular matrix receptor signaling and adhesion molecule integrin binding mediate VSMC-dependent neuronal development. Furthermore, we found that human arterial VSMCs promote neuronal development in multiple ways, including expanding the time window for nascent neurite initiation, increasing neuronal density, and promoting synchronized firing, whereas human umbilical vein VSMCs lack this capability. These in vitro data indicate that brain arteriolar VSMCs may carry direct instructive information for neural development through intercellular communication in vivo.
Collapse
Affiliation(s)
- Xuzhao Li
- grid.8547.e0000 0001 0125 2443Fudan University, Shanghai, 200433 China ,grid.494629.40000 0004 8008 9315Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Laboratory of Neurovascular Biology, Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, 310024 China
| | - Lili Zhou
- grid.494629.40000 0004 8008 9315Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Laboratory of Neurovascular Biology, Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, 310024 China ,grid.13402.340000 0004 1759 700XZhejiang University School of Medicine, Hangzhou, 310058 China
| | - Xiaoxuan Zhang
- grid.8547.e0000 0001 0125 2443Fudan University, Shanghai, 200433 China ,grid.494629.40000 0004 8008 9315Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Laboratory of Neurovascular Biology, Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, 310024 China
| | - Yuxiao Jin
- grid.8547.e0000 0001 0125 2443School of Life Sciences, Fudan University, Shanghai, 200438 China
| | - Bingrui Zhao
- grid.494629.40000 0004 8008 9315Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Laboratory of Neurovascular Biology, Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, 310024 China
| | - Dongdong Zhang
- grid.494629.40000 0004 8008 9315Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Laboratory of Neurovascular Biology, Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, 310024 China
| | - Chengjie Xi
- grid.40263.330000 0004 1936 9094Biotechnology Master’s Program, Brown University, Providence, USA
| | - Jiayu Ruan
- grid.494629.40000 0004 8008 9315Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Laboratory of Neurovascular Biology, Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, 310024 China
| | - Zhu Zhu
- grid.494629.40000 0004 8008 9315Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Laboratory of Neurovascular Biology, Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, 310024 China
| | - Jie-Min Jia
- grid.494629.40000 0004 8008 9315Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, 310024 China ,grid.494629.40000 0004 8008 9315Laboratory of Neurovascular Biology, Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, 310024 China
| |
Collapse
|
23
|
Liu R, Sun L, Wang Y, Jia M, Wang Q, Cai X, Wu J. Double-edged Role of K Na Channels in Brain Tuning: Identifying Epileptogenic Network Micro-Macro Disconnection. Curr Neuropharmacol 2022; 20:916-928. [PMID: 34911427 PMCID: PMC9881102 DOI: 10.2174/1570159x19666211215104829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/09/2021] [Accepted: 12/10/2021] [Indexed: 11/22/2022] Open
Abstract
Epilepsy is commonly recognized as a disease driven by generalized hyperexcited and hypersynchronous neural activity. Sodium-activated potassium channels (KNa channels), which are encoded by the Slo 2.2 and Slo 2.1 genes, are widely expressed in the central nervous system and considered as "brakes" to adjust neuronal adaptation through regulating action potential threshold or after-hyperpolarization under physiological condition. However, the variants in KNa channels, especially gain-of-function variants, have been found in several childhood epileptic conditions. Most previous studies focused on mapping the epileptic network on the macroscopic scale while ignoring the value of microscopic changes. Notably, paradoxical role of KNa channels working on individual neuron/microcircuit and the macroscopic epileptic expression highlights the importance of understanding epileptogenic network through combining microscopic and macroscopic methods. Here, we first illustrated the molecular and physiological function of KNa channels on preclinical seizure models and patients with epilepsy. Next, we summarized current hypothesis on the potential role of KNa channels during seizures to provide essential insight into what emerged as a micro-macro disconnection at different levels. Additionally, we highlighted the potential utility of KNa channels as therapeutic targets for developing innovative anti-seizure medications.
Collapse
Affiliation(s)
- Ru Liu
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Lei Sun
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China
| | | | - Meng Jia
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Qun Wang
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China
| | - Xiang Cai
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,Address correspondence to these authors at the Beijing Tiantan Hospital, Capital Medical University, Beijing, China; Tel: +0086-18062552085; E-mail: Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China; Tel: +0086-13319285082; E-mail:
| | - Jianping Wu
- Beijing Tiantan Hospital, Capital Medical University, Beijing, China;,Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China;,China National Clinical Research Center for Neurological Diseases, Beijing, China;,Address correspondence to these authors at the Beijing Tiantan Hospital, Capital Medical University, Beijing, China; Tel: +0086-18062552085; E-mail: Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China; Tel: +0086-13319285082; E-mail:
| |
Collapse
|
24
|
Gertler TS, Cherian S, DeKeyser JM, Kearney JA, George AL. K Na1.1 gain-of-function preferentially dampens excitability of murine parvalbumin-positive interneurons. Neurobiol Dis 2022; 168:105713. [PMID: 35346832 PMCID: PMC9169414 DOI: 10.1016/j.nbd.2022.105713] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/07/2022] [Accepted: 03/24/2022] [Indexed: 10/25/2022] Open
Abstract
KCNT1 encodes the sodium-activated potassium channel KNa1.1, expressed preferentially in the frontal cortex, hippocampus, cerebellum, and brainstem. Pathogenic missense variants in KCNT1 are associated with intractable epilepsy, namely epilepsy of infancy with migrating focal seizures (EIMFS), and sleep-related hypermotor epilepsy (SHE). In vitro studies of pathogenic KCNT1 variants support predominantly a gain-of-function molecular mechanism, yet how these variants behave in a neuron or ultimately drive formation of an epileptogenic circuit is an important and timely question. Using CRISPR/Cas9 gene editing, we introduced a gain-of-function variant into the endogenous mouse Kcnt1 gene. Compared to wild-type (WT) littermates, heterozygous and homozygous knock-in mice displayed greater seizure susceptibility to the chemoconvulsants kainate and pentylenetetrazole (PTZ), but not to flurothyl. Using acute slice electrophysiology in heterozygous and homozygous Kcnt1 knock-in and WT littermates, we demonstrated that CA1 hippocampal pyramidal neurons exhibit greater amplitude of miniature inhibitory postsynaptic currents in mutant mice with no difference in frequency, suggesting greater inhibitory tone associated with the Kcnt1 mutation. To address alterations in GABAergic signaling, we bred Kcnt1 knock-in mice to a parvalbumin-tdTomato reporter line, and found that parvalbumin-expressing (PV+) interneurons failed to fire repetitively with large amplitude current injections and were more prone to depolarization block. These alterations in firing can be recapitulated by direct application of the KNa1.1 channel activator loxapine in WT but are occluded in knock-in littermates, supporting a direct channel gain-of-function mechanism. Taken together, these results suggest that KNa1.1 gain-of-function dampens interneuron excitability to a greater extent than it impacts pyramidal neuron excitability, driving seizure susceptibility in a mouse model of KCNT1-associated epilepsy.
Collapse
Affiliation(s)
- Tracy S Gertler
- Division of Pediatric Neurology, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL 60611, United States of America; Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, United States of America.
| | - Suraj Cherian
- Division of Pediatric Neurology, Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL 60611, United States of America; Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, United States of America
| | - Jean-Marc DeKeyser
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, United States of America
| | - Jennifer A Kearney
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, United States of America
| | - Alfred L George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, United States of America.
| |
Collapse
|
25
|
Encephalopathy-causing mutations in Gβ 1 ( GNB1) alter regulation of neuronal GIRK channels. iScience 2021; 24:103018. [PMID: 34522861 PMCID: PMC8426278 DOI: 10.1016/j.isci.2021.103018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/04/2021] [Accepted: 08/18/2021] [Indexed: 11/24/2022] Open
Abstract
Mutations in the GNB1 gene, encoding the Gβ1 subunit of heterotrimeric G proteins, cause GNB1 Encephalopathy. Patients experience seizures, pointing to abnormal activity of ion channels or neurotransmitter receptors. We studied three Gβ1 mutations (K78R, I80N and I80T) using computational and functional approaches. In heterologous expression models, these mutations did not alter the coupling between G protein-coupled receptors to Gi/o, or the Gβγ regulation of the neuronal voltage-gated Ca2+ channel CaV2.2. However, the mutations profoundly affected the Gβγ regulation of the G protein-gated inwardly rectifying potassium channels (GIRK, or Kir3). Changes were observed in Gβ1 protein expression levels, Gβγ binding to cytosolic segments of GIRK subunits, and in Gβγ function, and included gain-of-function for K78R or loss-of-function for I80T/N, which were GIRK subunit-specific. Our findings offer new insights into subunit-dependent gating of GIRKs by Gβγ, and indicate diverse etiology of GNB1 Encephalopathy cases, bearing a potential for personalized treatment. GIRK channels are key players affected by GNB1 mutations under study (K78R and I80N/T) Effects of mutations (LoF or GoF) are channel subunit composition-specific The findings help to understand the GNB1 encephalopathy and to devise treatments The results yield new insights into mechanisms of Gβγ regulation of GIRKs
Collapse
|
26
|
A Novel KCNA2 Variant in a Patient with Non-Progressive Congenital Ataxia and Epilepsy: Functional Characterization and Sensitivity to 4-Aminopyridine. Int J Mol Sci 2021; 22:ijms22189913. [PMID: 34576077 PMCID: PMC8469797 DOI: 10.3390/ijms22189913] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/02/2021] [Accepted: 09/08/2021] [Indexed: 12/26/2022] Open
Abstract
Kv1.2 channels, encoded by the KCNA2 gene, are localized in the central and peripheral nervous system, where they regulate neuronal excitability. Recently, heterozygous mutations in KCNA2 have been associated with a spectrum of symptoms extending from epileptic encephalopathy, intellectual disability, and cerebellar ataxia. Patients are treated with a combination of antiepileptic drugs and 4-aminopyridine (4-AP) has been recently trialed in specific cases. We identified a novel variant in KCNA2, E236K, in a Serbian proband with non-progressive congenital ataxia and early onset epilepsy, treated with sodium valproate. To ascertain the pathogenicity of E236K mutation and to verify its sensitivity to 4-AP, we transfected HEK 293 cells with Kv1.2 WT or E236K cDNAs and recorded potassium currents through the whole-cell patch-clamp. In silico analysis supported the electrophysiological data. E236K channels showed voltage-dependent activation shifted towards negative potentials and slower kinetics of deactivation and activation compared with Kv1.2 WT. Heteromeric Kv1.2 WT+E236K channels, resembling the condition of the heterozygous patient, confirmed a mixed gain- and loss-of-function (GoF/LoF) biophysical phenotype. 4-AP inhibited both Kv1.2 and E236K channels with similar potency. Homology modeling studies of mutant channels suggested a reduced interaction between the residue K236 in the S2 segment and the gating charges at S4. Overall, the biophysical phenotype of E236K channels correlates with the mild end of the clinical spectrum reported in patients with GoF/LoF defects. The response to 4-AP corroborates existing evidence that KCNA2-disorders could benefit from variant-tailored therapeutic approaches, based on functional studies.
Collapse
|
27
|
Perszyk RE, Kristensen AS, Lyuboslavsky P, Traynelis SF. Three-dimensional missense tolerance ratio analysis. Genome Res 2021; 31:1447-1461. [PMID: 34301626 PMCID: PMC8327912 DOI: 10.1101/gr.275528.121] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 06/15/2021] [Indexed: 12/11/2022]
Abstract
A wealth of genetic information is available describing single-nucleotide variants in the human population that appear to be well-tolerated and in and of themselves do not confer disease. These variant data sets contain signatures about the protein structure-function relationships and provide an unbiased view of various protein functions in the context of human health. This information can be used to determine regional intolerance to variation, defined as the missense tolerance ratio (MTR), which is an indicator of stretches of the polypeptide chain that can tolerate changes without compromising protein function in a manner that impacts human health. This approach circumvents the lack of comprehensive data by averaging the data from adjacent residues on the polypeptide chain. We reasoned that many motifs in proteins consist of nonadjacent residues, but together function as a unit. We therefore developed an approach to analyze nearest neighbors in three-dimensional space as determined by crystallography rather than on the polypeptide chain. We used members of the GRIN gene family that encode subunits of NMDA-type ionotropic glutamate receptors (iGluRs) to exemplify the differences between these methods. Our method, 3DMTR, provides new information about regions of intolerance within iGluRs, allows consideration of protein-protein interfaces in multimeric proteins, and moves this important research tool from one-dimensional analysis to a structurally relevant tool. We validate the improved 3DMTR score by showing that it more accurately classifies the functional consequences of a set of newly measured and published point mutations of Grin family genes than existing methods.
Collapse
Affiliation(s)
- Riley E Perszyk
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Anders S Kristensen
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Polina Lyuboslavsky
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
| | - Stephen F Traynelis
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Center for Functional Evaluation of Rare Variants (CFERV), Emory University School of Medicine, Atlanta, Georgia 30322, USA
| |
Collapse
|
28
|
Zhang Y, Ali SR, Nabbout R, Barcia G, Kaczmarek LK. A KCNC1 mutation in epilepsy of infancy with focal migrating seizures produces functional channels that fail to be regulated by PKC phosphorylation. J Neurophysiol 2021; 126:532-539. [PMID: 34232791 DOI: 10.1152/jn.00257.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Channelopathies caused by mutations in genes encoding ion channels generally produce a clear change in channel function. Accordingly, mutations in KCNC1, which encodes the voltage-dependent Kv3.1 potassium channel, result in progressive myoclonus epilepsy as well as other developmental and epileptic encephalopathies, and these have been shown to reduce or fully abolish current amplitude. One exception to this is the mutation A513V Kv3.1b, located in the cytoplasmic C-terminal domain of the channel protein. This de novo variant was detected in a patient with epilepsy of infancy with focal migrating seizures (EIFMS), but no difference could be detected between A513V Kv3.1 current and that of wild-type Kv3.1. Using both biochemical and electrophysiological approaches, we have now confirmed that this variant produces functional channels but find that the A513V mutation renders the channel completely insensitive to regulation by phosphorylation at S503, a nearby regulatory site in the C-terminus. In this respect, the mutation resembles those in another channel, KCNT1, which are the major cause of EIFMS. Because the amplitude of Kv3.1 current is constantly adjusted by phosphorylation in vivo, our findings suggest that loss of such regulation contributes to EIFMS phenotype and emphasize the role of channel modulation for normal neuronal function.NEW & NOTEWORTHY Ion channel mutations that cause serious human diseases generally alter the biophysical properties or expression of the channel. We describe a de novo mutation in the Kv3.1 potassium channel that causes severe intellectual disability with early-onset epilepsy. The properties of this channel appear identical to those of wild-type channels, but the mutation prevents phosphorylation of the channel by protein kinase C. Our findings emphasize the role of channel modulation in normal brain function.
Collapse
Affiliation(s)
- Yalan Zhang
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut
| | - Syed R Ali
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut
| | - Rima Nabbout
- Department of Pediatric Neurology, Necker-Enfants Malades Hospital, Centre de Référence Épilepsies Rares, Member of ERN EPICARE, Institut Imagine, Université de Paris, Paris, France
| | - Giulia Barcia
- Department of Pediatric Neurology, Necker-Enfants Malades Hospital, Centre de Référence Épilepsies Rares, Member of ERN EPICARE, Institut Imagine, Université de Paris, Paris, France.,Department of Medical Genetics, Necker-Enfants Malades Hospital, Université de Paris, Paris, France
| | - Leonard K Kaczmarek
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut.,Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| |
Collapse
|
29
|
Abstract
Genetic testing has yielded major advances in our understanding of the causes of epilepsy. Seizures remain resistant to treatment in a significant proportion of cases, particularly in severe, childhood-onset epilepsy, the patient population in which an underlying causative genetic variant is most likely to be identified. A genetic diagnosis can be explanatory as to etiology, and, in some cases, might suggest a therapeutic approach; yet, a clear path from genetic diagnosis to treatment remains unclear in most cases. Here, we discuss theoretical considerations behind the attempted use of small molecules for the treatment of genetic epilepsies, which is but one among various approaches currently under development. We explore a few salient examples and consider the future of the small molecule approach for genetic epilepsies. We conclude that significant additional work is required to understand how genetic variation leads to dysfunction of epilepsy-associated protein targets, and how this impacts the function of diverse subtypes of neurons embedded within distributed brain circuits to yield epilepsy and epilepsy-associated comorbidities. A syndrome- or even variant-specific approach may be required to achieve progress. Advances in the field will require improved methods for large-scale target validation, compound identification and optimization, and the development of accurate model systems that reflect the core features of human epilepsy syndromes, as well as novel approaches towards clinical trials of such compounds in small rare disease cohorts.
Collapse
Affiliation(s)
- Ethan M Goldberg
- Department of Pediatrics, Division of Neurology, Abramson Research Center, The Epilepsy Neurogenetics Initiative, The Children's Hospital of Philadelphia, Abramson Research Center Room 502A, 19104, Philadelphia, PA, USA.
- Departments of Neurology and Neuroscience, The University of Pennsylvania Perelman School of Medicine, 19104, Philadelphia, PA, USA.
| |
Collapse
|
30
|
Cole BA, Clapcote SJ, Muench SP, Lippiat JD. Targeting K Na1.1 channels in KCNT1-associated epilepsy. Trends Pharmacol Sci 2021; 42:700-713. [PMID: 34074526 DOI: 10.1016/j.tips.2021.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 12/19/2022]
Abstract
Gain-of-function (GOF) pathogenic variants of KCNT1, the gene encoding the largest known potassium channel subunit, KNa1.1, are associated with developmental and epileptic encephalopathies accompanied by severe psychomotor and intellectual disabilities. Blocking hyperexcitable KNa1.1 channels with quinidine, a class I antiarrhythmic drug, has shown variable success in patients in part because of dose-limiting off-target effects, poor blood-brain barrier (BBB) penetration, and low potency. In recent years, high-resolution cryogenic electron microscopy (cryo-EM) structures of the chicken KNa1.1 channel in different activation states have been determined, and animal models of the diseases have been generated. Alongside increasing information about the functional effects of GOF pathogenic variants on KNa1.1 channel behaviour and how they lead to hyperexcitability, these tools will facilitate the development of more effective treatment strategies. We review the range of KCNT1 variants and their functional effects, the challenges posed by current treatment strategies, and recent advances in finding more potent and selective therapeutic interventions for KCNT1-related epilepsies.
Collapse
Affiliation(s)
- Bethan A Cole
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Steven J Clapcote
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Stephen P Muench
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | | |
Collapse
|
31
|
Cho JD, Kim YA, Rafikian EE, Yang M, Santa-Maria I. Marked Mild Cognitive Deficits in Humanized Mouse Model of Alzheimer's-Type Tau Pathology. Front Behav Neurosci 2021; 15:634157. [PMID: 34093145 PMCID: PMC8175658 DOI: 10.3389/fnbeh.2021.634157] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 04/21/2021] [Indexed: 01/23/2023] Open
Abstract
Hyperphosphorylation and the subsequent aggregation of tau protein into neurofibrillary tangles (NFTs) are well-established neuropathological hallmarks of Alzheimer’s disease (AD) and associated tauopathies. To further examine the impact and progression of human tau pathology in neurodegenerative contexts, the humanized tau (htau) mouse model was originally created. Despite AD-like tau pathological features recapitulated in the htau mouse model, robustness of behavioral phenotypes has not been fully established. With the ultimate goal of evaluating the htau mouse model as a candidate for testing AD therapeutics, we set out to verify, in-house, the presence of robust, replicable cognitive deficits in the htau mice. The present study shows behavioral data collected from a carefully curated battery of learning and memory tests. Here we report a significant short-term spatial memory deficit in aged htau mice, representing a novel finding in this model. However, we did not find salient impairments in long-term learning and memory previously reported in this mouse model. Here, we attempted to understand the discrepancies in the literature by highlighting the necessity of scrutinizing key procedural differences across studies. Reported cognitive deficits in the htau model may depend on task difficulty and other procedural details. While the htau mouse remains a unique and valuable animal model for replicating late onset AD-like human tau pathology, its cognitive deficits are modest under standard testing conditions. The overarching message is that before using any AD mouse model to evaluate treatment efficacies, it is imperative to first characterize and verify the presence of behavioral deficits in-house.
Collapse
Affiliation(s)
- Joshua D Cho
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, United States.,Department of Pathology & Cell Biology, Columbia University, New York, NY, United States
| | - Yoon A Kim
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, United States.,Department of Pathology & Cell Biology, Columbia University, New York, NY, United States
| | - Elizabeth E Rafikian
- The Mouse NeuroBehavior Core, Institute for Genomic Medicine, Columbia University, New York, NY, United States
| | - Mu Yang
- The Mouse NeuroBehavior Core, Institute for Genomic Medicine, Columbia University, New York, NY, United States
| | - Ismael Santa-Maria
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, United States.,Department of Pathology & Cell Biology, Columbia University, New York, NY, United States
| |
Collapse
|
32
|
Griffin AM, Kahlig KM, Hatch RJ, Hughes ZA, Chapman ML, Antonio B, Marron BE, Wittmann M, Martinez-Botella G. Discovery of the First Orally Available, Selective K Na1.1 Inhibitor: In Vitro and In Vivo Activity of an Oxadiazole Series. ACS Med Chem Lett 2021; 12:593-602. [PMID: 33859800 PMCID: PMC8040054 DOI: 10.1021/acsmedchemlett.0c00675] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/01/2021] [Indexed: 12/15/2022] Open
Abstract
The gene KCNT1 encodes the sodium-activated potassium channel KNa1.1 (Slack, Slo2.2). Variants in the KCNT1 gene induce a gain-of-function (GoF) phenotype in ionic currents and cause a spectrum of intractable neurological disorders in infants and children, including epilepsy of infancy with migrating focal seizures (EIMFS) and autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Effective treatment options for KCNT1-related disease are absent, and novel therapies are urgently required. We describe the development of a novel class of oxadiazole KNa1.1 inhibitors, leading to the discovery of compound 31 that reduced seizures and interictal spikes in a mouse model of KCNT1 GoF.
Collapse
Affiliation(s)
- Andrew M Griffin
- Praxis Precision Medicines, Research Innovation, Cambridge, Massachusetts 02142, United States
| | - Kristopher M Kahlig
- Praxis Precision Medicines, Research Innovation, Cambridge, Massachusetts 02142, United States
| | - Robert John Hatch
- Praxis Precision Medicines, Research Innovation, Cambridge, Massachusetts 02142, United States
- The Florey Institute of Neuroscience and Mental Health, Melbourne, VIC 3052, Australia
| | - Zoë A Hughes
- Praxis Precision Medicines, Research Innovation, Cambridge, Massachusetts 02142, United States
| | | | | | - Brian E Marron
- Praxis Precision Medicines, Research Innovation, Cambridge, Massachusetts 02142, United States
| | - Marion Wittmann
- Praxis Precision Medicines, Research Innovation, Cambridge, Massachusetts 02142, United States
| | | |
Collapse
|
33
|
Refining Genotypes and Phenotypes in KCNA2-Related Neurological Disorders. Int J Mol Sci 2021; 22:ijms22062824. [PMID: 33802230 PMCID: PMC7999221 DOI: 10.3390/ijms22062824] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 02/06/2023] Open
Abstract
Pathogenic variants in KCNA2, encoding for the voltage-gated potassium channel Kv1.2, have been identified as the cause for an evolving spectrum of neurological disorders. Affected individuals show early-onset developmental and epileptic encephalopathy, intellectual disability, and movement disorders resulting from cerebellar dysfunction. In addition, individuals with a milder course of epilepsy, complicated hereditary spastic paraplegia, and episodic ataxia have been reported. By analyzing phenotypic, functional, and genetic data from published reports and novel cases, we refine and further delineate phenotypic as well as functional subgroups of KCNA2-associated disorders. Carriers of variants, leading to complex and mixed channel dysfunction that are associated with a gain- and loss-of-potassium conductance, more often show early developmental abnormalities and an earlier onset of epilepsy compared to individuals with variants resulting in loss- or gain-of-function. We describe seven additional individuals harboring three known and the novel KCNA2 variants p.(Pro407Ala) and p.(Tyr417Cys). The location of variants reported here highlights the importance of the proline(405)–valine(406)–proline(407) (PVP) motif in transmembrane domain S6 as a mutational hotspot. A novel case of self-limited infantile seizures suggests a continuous clinical spectrum of KCNA2-related disorders. Our study provides further insights into the clinical spectrum, genotype–phenotype correlation, variability, and predicted functional impact of KCNA2 variants.
Collapse
|
34
|
Altered Fast Synaptic Transmission in a Mouse Model of DNM1-Associated Developmental Epileptic Encephalopathy. eNeuro 2021; 8:ENEURO.0269-20.2020. [PMID: 33372033 PMCID: PMC7986544 DOI: 10.1523/eneuro.0269-20.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 12/01/2020] [Accepted: 12/07/2020] [Indexed: 12/05/2022] Open
Abstract
Developmental epileptic encephalopathies (DEEs) are severe seizure disorders that occur in infants and young children, characterized by developmental delay, cognitive decline, and early mortality. Recent efforts have identified a wide variety of genetic variants that cause DEEs. Among these, variants in the DNM1 gene have emerged as definitive causes of DEEs, including infantile spasms and Lennox–Gastaut syndrome. A mouse model of Dnm1-associated DEE, known as “Fitful” (Dnm1Ftfl), recapitulates key features of the disease, including spontaneous seizures, early lethality, and neuronal degeneration. Previous work showed that DNM1 is a key regulator of synaptic vesicle (SV) endocytosis and synaptic transmission and suggested that inhibitory neurotransmission may be more reliant on DNM1 function than excitatory transmission. The Dnm1Ftfl variant is thought to encode a dominant negative DNM1 protein; however, the effects of the Dnm1Ftfl variant on synaptic transmission are largely unknown. To understand these synaptic effects, we recorded from pairs of cultured mouse cortical neurons and characterized all four major connection types [excitation of excitation (E-E), inhibition of inhibition (I-I), E-I, I-E]. Miniature and spontaneous EPSCs and IPSCs were larger, but less frequent, at all Dnm1Ftfl synaptic types, and Dnm1Ftfl neurons had reduced expression of excitatory and inhibitory SV markers. Baseline evoked transmission, however, was reduced only at inhibitory synapses onto excitatory neurons, because of a smaller pool of releasable SVs. In addition to these synaptic alterations, Dnm1Ftfl neurons degenerated later in development, although their activity levels were reduced, suggesting that Dnm1Ftfl may impair synaptic transmission and neuronal health through distinct mechanisms.
Collapse
|
35
|
Maguire JL. Same Channel, Different Tune. Epilepsy Curr 2021; 21:111-113. [PMID: 34025287 PMCID: PMC8010877 DOI: 10.1177/1535759720986837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Reduced GABAergic Neuron Excitability, Altered Synaptic Connectivity, and Seizures in a KCNT1 Gain-of-Function Mouse Model of Childhood Epilepsy Shore AN, Colombo S, Tobin WF, et al. Cell Rep . 2020;33(4):108303.doi:10.1016/j.celrep.2020.108303 Gain-of-function (GOF) variants in K+ channels cause severe childhood epilepsies, but there are no mechanisms to explain how increased K+ currents lead to network hyperexcitability. Here, we introduce a human Na+-activated K+ (KNa) channel variant (KCNT1-Y796H) into mice, and using a multiplatform approach, find motor cortex hyperexcitability and early-onset seizures, phenotypes strikingly similar to those of human patients. Although the variant increases KNa currents in cortical excitatory and inhibitory neurons, there is an increase in the KNa current across subthreshold voltages only in inhibitory neurons, particularly in those with non-fast-spiking properties, resulting in inhibitory neuron-specific impairments in excitability and action potential generation. We further observe evidence of synaptic rewiring, including increases in homotypic synaptic connectivity, accompanied by network hyperexcitability and hypersynchronicity. These findings support inhibitory neuron-specific mechanisms in mediating the epileptogenic effects of KCNT1 channel GOF, offering cell type–specific currents and effects as promising targets for therapeutic intervention.
Collapse
|
36
|
Kuchenbuch M, Nabbout R, Yochum M, Sauleau P, Modolo J, Wendling F, Benquet P. In silico model reveals the key role of GABA in KCNT1-epilepsy in infancy with migrating focal seizures. Epilepsia 2021; 62:683-697. [PMID: 33617692 DOI: 10.1111/epi.16834] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 12/08/2020] [Accepted: 01/18/2021] [Indexed: 02/06/2023]
Abstract
OBJECTIVE This study was undertaken to investigate how gain of function (GOF) of slack channel due to a KCNT1 pathogenic variant induces abnormal neuronal cortical network activity and generates specific electroencephalographic (EEG) patterns of epilepsy in infancy with migrating focal seizures. METHODS We used detailed microscopic computational models of neurons to explore the impact of GOF of slack channel (explicitly coded) on each subtype of neurons and on a cortical micronetwork. Then, we adapted a thalamocortical macroscopic model considering results obtained in detailed models and immature properties related to epileptic brain in infancy. Finally, we compared simulated EEGs resulting from the macroscopic model with interictal and ictal patterns of affected individuals using our previously reported EEG markers. RESULTS The pathogenic variants of KCNT1 strongly decreased the firing rate properties of γ-aminobutyric acidergic (GABAergic) interneurons and, to a lesser extent, those of pyramidal cells. This change led to hyperexcitability with increased synchronization in a cortical micronetwork. At the macroscopic scale, introducing slack GOF effect resulted in epilepsy of infancy with migrating focal seizures (EIMFS) EEG interictal patterns. Increased excitation-to-inhibition ratio triggered seizure, but we had to add dynamic depolarizing GABA between somatostatin-positive interneurons and pyramidal cells to obtain migrating seizure. The simulated migrating seizures were close to EIMFS seizures, with similar values regarding the delay between the different ictal activities (one of the specific EEG markers of migrating focal seizures due to KCNT1 pathogenic variants). SIGNIFICANCE This study illustrates the interest of biomathematical models to explore pathophysiological mechanisms bridging the gap between the functional effect of gene pathogenic variants and specific EEG phenotype. Such models can be complementary to in vitro cellular and animal models. This multiscale approach provides an in silico framework that can be further used to identify candidate innovative therapies.
Collapse
Affiliation(s)
- Mathieu Kuchenbuch
- LTSI-U1099, Université de Rennes 1, INSERM, Rennes, France.,Department of Pediatric Neurology, Reference Center for Rare Epilepsies, Hôpital Necker-Enfants malades, member of European Network EPICARE, Paris, France.,Laboratory of Translational Research for Neurological Disorders (UMR 1163), IHU Imagine Institute of Genetic Diseases, INSERM, University of Paris, Paris, France
| | - Rima Nabbout
- Department of Pediatric Neurology, Reference Center for Rare Epilepsies, Hôpital Necker-Enfants malades, member of European Network EPICARE, Paris, France.,Laboratory of Translational Research for Neurological Disorders (UMR 1163), IHU Imagine Institute of Genetic Diseases, INSERM, University of Paris, Paris, France
| | - Maxime Yochum
- LTSI-U1099, Université de Rennes 1, INSERM, Rennes, France
| | - Paul Sauleau
- CHU de Rennes (Department of Neurophysiology), "Behavior and Basal Ganglia" Research Unit (EA4712), University of Rennes, Rennes, France
| | - Julien Modolo
- LTSI-U1099, Université de Rennes 1, INSERM, Rennes, France
| | | | - Pascal Benquet
- LTSI-U1099, Université de Rennes 1, INSERM, Rennes, France
| |
Collapse
|
37
|
Wang W, Frankel WN. Overlaps, gaps, and complexities of mouse models of Developmental and Epileptic Encephalopathy. Neurobiol Dis 2021; 148:105220. [PMID: 33301879 PMCID: PMC8547712 DOI: 10.1016/j.nbd.2020.105220] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/17/2020] [Accepted: 12/04/2020] [Indexed: 11/28/2022] Open
Abstract
Mouse models have made innumerable contributions to understanding the genetic basis of neurological disease and pathogenic mechanisms and to therapy development. Here we consider the current state of mouse genetic models of Developmental and Epileptic Encephalopathy (DEE), representing a set of rare but devastating and largely intractable childhood epilepsies. By examining the range of mouse lines available in this rapidly moving field and by detailing both expected and unusual features in representative examples, we highlight lessons learned in an effort to maximize the full potential of this powerful resource for preclinical studies.
Collapse
Affiliation(s)
- Wanqi Wang
- Department of Genetics & Development, Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America.
| | - Wayne N Frankel
- Department of Genetics & Development, Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States of America.
| |
Collapse
|