1
|
Yu W, Hill SF, Huang Y, Zhu L, Demetriou Y, Ziobro J, Reger F, Jia X, Mattis J, Meisler MH. Allele-Specific Editing of a Dominant SCN8A Epilepsy Variant Protects against Seizures and Lethality in a Murine Model. Ann Neurol 2024. [PMID: 39158034 DOI: 10.1002/ana.27053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 06/18/2024] [Accepted: 07/26/2024] [Indexed: 08/20/2024]
Abstract
OBJECTIVE Developmental and epileptic encephalopathies (DEEs) can result from dominant, gain of function variants of neuronal ion channels. More than 450 de novo missense variants of the sodium channel gene SCN8A have been identified in individuals with DEE. METHODS We studied a mouse model carrying the patient Scn8a variant p.Asn1768Asp. An AAV-PHP.eB virus carrying an allele-specific single guide RNA (sgRNA) was administered by intracerebroventricular injection. Cas9 was provided by an inherited transgene. RESULTS Allele-specific disruption of the reading frame of the pathogenic transcript generated out-of-frame indels in 1/4 to 1/3 of transcripts throughout the brain. This editing efficiency was sufficient to rescue lethality and seizures. Neuronal hyperexcitability was reduced in cells expressing the virus. INTERPRETATION The data demonstrate efficient allele-specific editing of a dominant missense variant and support the feasibility of allele-specific therapy for DEE epilepsy. ANN NEUROL 2024.
Collapse
Affiliation(s)
- Wenxi Yu
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - Sophie F Hill
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI
| | - Yumei Huang
- Center for Genomic Technologies, Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, Guangzhou, China
| | - Limei Zhu
- Department of Neurology, University of Michigan, Ann Arbor, MI
| | | | - Julie Ziobro
- Department of Pediatrics, University of Michigan, Ann Arbor, MI
| | - Faith Reger
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - Xiaoyan Jia
- Center for Genomic Technologies, Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, Guangzhou, China
| | - Joanna Mattis
- Department of Neurology, University of Michigan, Ann Arbor, MI
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI
| |
Collapse
|
2
|
Tamura T, Shimojima Yamamoto K, Tohyama J, Morioka I, Kanno H, Yamamoto T. Reciprocal chromosome translocation t(3;4)(q27;q31.2) with deletion of 3q27 and reduced FBXW7 expression in a patient with developmental delay, hypotonia, and seizures. J Hum Genet 2024:10.1038/s10038-024-01286-x. [PMID: 39123068 DOI: 10.1038/s10038-024-01286-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 07/26/2024] [Accepted: 08/01/2024] [Indexed: 08/12/2024]
Abstract
Reciprocal chromosomal translocation is one of genomic variations. When cytogenetically de novo reciprocal translocations are identified in patients with some clinical manifestations, the genes in the breakpoints are considered to be related to the clinical features. In this study, we encountered a patient with severe developmental delay, intractable epilepsy, growth failure, distinctive features, and skeletal manifestations. Conventional karyotyping revealed a de novo translocation described as 46,XY,t(3;4)(q27;q31.2). Chromosomal microarray testing detected a 1.25-Mb microdeletion at 3q27.3q28. Although the skeletal manifestations may have been affected by this deletion, the neurological features of this patient were severe and could not be fully explained by this deletion. Since no genomic copy number aberration was detected on chromosome 4, long-read whole-genome sequencing analysis was performed and a precise breakpoint was confirmed. A 460-bp deletion was detected between the two breakpoints; however, no gene was disrupted. FBXW7, the gene responsible for developmental delay, hypotonia, and impaired language, is in the 0.5-Mb telomeric region. Most of the patient's clinical features were considered consistent with symptoms of FBXW7-related disorders, but were more severe. FBXW7 expression in the immortalized lymphoblasts of the patient was reduced compared to that in controls. Based on these findings, we suspect that FBXW7 is affected by downstream position effects of chromosomal translocations. The severe neurological features of the patient may have been affected not only by the 3q27-q28 deletion but also by impaired expression of FBXW7 derived from the breakage of chromosome 4.
Collapse
Affiliation(s)
- Takeaki Tamura
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
- Division of Gene Medicine, Graduate School of Medical Science, Tokyo Women's Medical University, Tokyo, Japan
- Department of Transfusion Medicine and Cell Processing, Tokyo Women's Medical University, Tokyo, Japan
| | - Keiko Shimojima Yamamoto
- Department of Transfusion Medicine and Cell Processing, Tokyo Women's Medical University, Tokyo, Japan
- Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan
| | - Jun Tohyama
- Department of Child Neurology, National Hospital Organization Nishiniigata Chuo Hospital, Niigata, Japan
| | - Ichiro Morioka
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Hitoshi Kanno
- Department of Transfusion Medicine and Cell Processing, Tokyo Women's Medical University, Tokyo, Japan
| | - Toshiyuki Yamamoto
- Division of Gene Medicine, Graduate School of Medical Science, Tokyo Women's Medical University, Tokyo, Japan.
- Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan.
| |
Collapse
|
3
|
Quinn S, Zhang N, Fenton TA, Brusel M, Muruganandam P, Peleg Y, Giladi M, Haitin Y, Lerche H, Bassan H, Liu Y, Ben-Shalom R, Rubinstein M. Complex biophysical changes and reduced neuronal firing in an SCN8A variant associated with developmental delay and epilepsy. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167127. [PMID: 38519006 DOI: 10.1016/j.bbadis.2024.167127] [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: 12/17/2023] [Revised: 03/07/2024] [Accepted: 03/12/2024] [Indexed: 03/24/2024]
Abstract
Mutations in the SCN8A gene, encoding the voltage-gated sodium channel NaV1.6, are associated with a range of neurodevelopmental syndromes. The p.(Gly1625Arg) (G1625R) mutation was identified in a patient diagnosed with developmental epileptic encephalopathy (DEE). While most of the characterized DEE-associated SCN8A mutations were shown to cause a gain-of-channel function, we show that the G1625R variant, positioned within the S4 segment of domain IV, results in complex effects. Voltage-clamp analyses of NaV1.6G1625R demonstrated a mixture of gain- and loss-of-function properties, including reduced current amplitudes, increased time constant of fast voltage-dependent inactivation, a depolarizing shift in the voltage dependence of activation and inactivation, and increased channel availability with high-frequency repeated depolarization. Current-clamp analyses in transfected cultured neurons revealed that these biophysical properties caused a marked reduction in the number of action potentials when firing was driven by the transfected mutant NaV1.6. Accordingly, computational modeling of mature cortical neurons demonstrated a mild decrease in neuronal firing when mimicking the patients' heterozygous SCN8A expression. Structural modeling of NaV1.6G1625R suggested the formation of a cation-π interaction between R1625 and F1588 within domain IV. Double-mutant cycle analysis revealed that this interaction affects the voltage dependence of inactivation in NaV1.6G1625R. Together, our studies demonstrate that the G1625R variant leads to a complex combination of gain and loss of function biophysical changes that result in an overall mild reduction in neuronal firing, related to the perturbed interaction network within the voltage sensor domain, necessitating personalized multi-tiered analysis for SCN8A mutations for optimal treatment selection.
Collapse
Affiliation(s)
- Shir Quinn
- Goldschleger Eye Research Institute, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Nan Zhang
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Tuebingen, Germany
| | - Timothy A Fenton
- Neurology Department, MIND Institute, University of California, Davis, Sacramento, CA, United States
| | - Marina Brusel
- Goldschleger Eye Research Institute, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Preethi Muruganandam
- Neurology Department, MIND Institute, University of California, Davis, Sacramento, CA, United States
| | - Yoav Peleg
- Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Moshe Giladi
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Yoni Haitin
- Department of Physiology and Pharmacology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Tuebingen, Germany
| | - Haim Bassan
- Pediatric Neurology and Development Center, Shamir Medical Center (Assaf Harofeh), Zerifin, Israel; Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yuanyuan Liu
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Tuebingen, Germany.
| | - Roy Ben-Shalom
- Neurology Department, MIND Institute, University of California, Davis, Sacramento, CA, United States.
| | - Moran Rubinstein
- Goldschleger Eye Research Institute, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Human Molecular Genetics and Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
| |
Collapse
|
4
|
Qu G, Merchant JP, Clatot J, DeFlitch LM, Frederick DJ, Tang S, Salvatore M, Zhang X, Li J, Anderson SA, Goldberg EM. Targeted blockade of aberrant sodium current in a stem cell-derived neuron model of SCN3A encephalopathy. Brain 2024; 147:1247-1263. [PMID: 37935051 PMCID: PMC10994535 DOI: 10.1093/brain/awad376] [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: 06/28/2023] [Revised: 09/30/2023] [Accepted: 10/20/2023] [Indexed: 11/09/2023] Open
Abstract
Missense variants in SCN3A encoding the voltage-gated sodium (Na+) channel α subunit Nav1.3 are associated with SCN3A-related neurodevelopmental disorder (SCN3A-NDD), a spectrum of disease that includes epilepsy and malformation of cortical development. How genetic variation in SCN3A leads to pathology remains unclear, as prior electrophysiological work on disease-associated variants has been performed exclusively in heterologous cell systems. To further investigate the mechanisms of SCN3A-NDD pathogenesis, we used CRISPR/Cas9 gene editing to modify a control human induced pluripotent stem cell (iPSC) line to express the recurrent de novo missense variant SCN3A c.2624T>C (p.Ile875Thr). With the established Ngn2 rapid induction protocol, we generated glutamatergic forebrain-like neurons (iNeurons), which we showed to express SCN3A mRNA and Nav1.3-mediated Na+ currents. We performed detailed whole-cell patch clamp recordings to determine the effect of the SCN3A-p.Ile875Thr variant on endogenous Na+ currents in, and intrinsic excitability of, human neurons. Compared to control iNeurons, variant-expressing iNeurons exhibit markedly increased slowly-inactivating/persistent Na+ current, abnormal firing patterns with paroxysmal bursting and plateau-like potentials with action potential failure, and a hyperpolarized voltage threshold for action potential generation. We then validated these findings using a separate iPSC line generated from a patient harbouring the SCN3A-p.Ile875Thr variant compared to a corresponding CRISPR-corrected isogenic control line. Finally, we found that application of the Nav1.3-selective blocker ICA-121431 normalizes action potential threshold and aberrant firing patterns in SCN3A-p.Ile1875Thr iNeurons; in contrast, consistent with action as a Na+ channel blocker, ICA-121431 decreases excitability of control iNeurons. Our findings demonstrate that iNeurons can model the effects of genetic variation in SCN3A yet reveal a complex relationship between gain-of-function at the level of the ion channel versus impact on neuronal excitability. Given the transient expression of SCN3A in the developing human nervous system, selective blockade or suppression of Nav1.3-containing Na+ channels could represent a therapeutic approach towards SCN3A-NDD.
Collapse
Affiliation(s)
- Guojie Qu
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Julie P Merchant
- Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Jérôme Clatot
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- The Epilepsy NeuroGenetics Initiative, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Leah M DeFlitch
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Danny J Frederick
- Department of Child and Adolescent Psychiatry, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Sheng Tang
- Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Madeleine Salvatore
- Department of Child and Adolescent Psychiatry, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Xiaohong Zhang
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Jianping Li
- Department of Child and Adolescent Psychiatry, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Stewart A Anderson
- The Epilepsy NeuroGenetics Initiative, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Child and Adolescent Psychiatry, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Ethan M Goldberg
- Division of Neurology, Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Neuroscience, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
- The Epilepsy NeuroGenetics Initiative, The Children’s Hospital of Philadelphia, Philadelphia, PA, 19104, USA
- Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
| |
Collapse
|
5
|
Hill SF, Yu W, Ziobro J, Chalasani S, Reger F, Meisler MH. Long-Term Downregulation of the Sodium Channel Gene Scn8a Is Therapeutic in Mouse Models of SCN8A Epilepsy. Ann Neurol 2024; 95:754-759. [PMID: 38113311 PMCID: PMC11170564 DOI: 10.1002/ana.26861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 11/06/2023] [Accepted: 12/14/2023] [Indexed: 12/21/2023]
Abstract
OBJECTIVE De novo mutations of the voltage-gated sodium channel gene SCN8A cause developmental and epileptic encephalopathy (DEE). Most pathogenic variants result in gain-of-function changes in activity of the sodium channel Nav1.6, poorly controlled seizures, and significant comorbidities. In previous work, an antisense oligonucleotide (ASO) reduced Scn8a transcripts and increased lifespan after neonatal administration to a mouse model. Here, we tested long-term ASO treatment initiated after seizure onset, as required for clinical application. METHODS ASO treatment was initiated after observation of a convulsive seizure and repeated at 4 to 6 week intervals for 1 year. We also tested the long-term efficacy of an AAV10-short hairpin RNA (shRNA) virus administered on P1. RESULTS Repeated treatment with the Scn8a ASO initiated after seizure onset provided long-term survival and reduced seizure frequency during a 12 month observation period. A single treatment with viral shRNA was also protective during 12 months of observation. INTERPRETATION Downregulation of Scn8a expression that is initiated after the onset of seizures is effective for long-term treatment in a model of SCN8A-DEE. Repeated ASO administration or a single dose of viral shRNA prevented seizures and extended survival through 12 months of observation. ANN NEUROL 2024;95:754-759.
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
| | - Wenxi Yu
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - Julie Ziobro
- Department of Pediatrics, University of Michigan, Ann Arbor, MI
| | - Sanjna Chalasani
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - Faith Reger
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - Miriam H Meisler
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, United States
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
- Department of Neurology, University of Michigan, Ann Arbor, MI
| |
Collapse
|
6
|
Miralles RM, Boscia AR, Kittur S, Vundela SR, Wengert ER, Patel MK. Parvalbumin Interneuron Impairment Leads to Synaptic Transmission Deficits and Seizures in SCN8A Epileptic Encephalopathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.09.579511. [PMID: 38464208 PMCID: PMC10925130 DOI: 10.1101/2024.02.09.579511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
SCN8A epileptic encephalopathy (EE) is a severe epilepsy syndrome resulting from de novo mutations in the voltage-gated sodium channel Na v 1.6, encoded by the gene SCN8A . Na v 1.6 is expressed in both excitatory and inhibitory neurons, yet previous studies have primarily focused on the impact SCN8A mutations have on excitatory neuron function, with limited studies on the importance of inhibitory interneurons to seizure onset and progression. Inhibitory interneurons are critical in balancing network excitability and are known to contribute to the pathophysiology of other epilepsies. Parvalbumin (PV) interneurons are the most prominent inhibitory neuron subtype in the brain, making up about 40% of inhibitory interneurons. Notably, PV interneurons express high levels of Na v 1.6. To assess the role of PV interneurons within SCN8A EE, we used two mouse models harboring patient-derived SCN8A gain-of-function mutations, Scn8a D/+ , where the SCN8A mutation N1768D is expressed globally, and Scn8a W/+ -PV, where the SCN8A mutation R1872W is selectively expressed in PV interneurons. Expression of the R1872W SCN8A mutation selectively in PV interneurons led to the development of spontaneous seizures in Scn8a W/+ -PV mice and seizure-induced death, decreasing survival compared to wild-type. Electrophysiology studies showed that PV interneurons in Scn8a D/+ and Scn8a W/+ -PV mice were susceptible to depolarization block, a state of action potential failure. Scn8a D/+ and Scn8a W/+ -PV interneurons also exhibited increased persistent sodium current, a hallmark of SCN8A gain-of-function mutations that contributes to depolarization block. Evaluation of synaptic connections between PV interneurons and pyramidal cells showed an increase in synaptic transmission failure at high frequencies (80-120Hz) as well as an increase in synaptic latency in Scn8a D/+ and Scn8a W/+ -PV interneurons. These data indicate a distinct impairment of synaptic transmission in SCN8A EE, potentially decreasing overall cortical network inhibition. Together, our novel findings indicate that failure of PV interneuron spiking via depolarization block along with frequency-dependent inhibitory synaptic impairment likely elicits an overall reduction in the inhibitory drive in SCN8A EE, leading to unchecked excitation and ultimately resulting in seizures and seizure-induced death.
Collapse
|
7
|
Xiao W, Li P, Kong F, Kong J, Pan A, Long L, Yan X, Xiao B, Gong J, Wan L. Unraveling the Neural Circuits: Techniques, Opportunities and Challenges in Epilepsy Research. Cell Mol Neurobiol 2024; 44:27. [PMID: 38443733 PMCID: PMC10914928 DOI: 10.1007/s10571-024-01458-5] [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: 12/25/2023] [Accepted: 01/24/2024] [Indexed: 03/07/2024]
Abstract
Epilepsy, a prevalent neurological disorder characterized by high morbidity, frequent recurrence, and potential drug resistance, profoundly affects millions of people globally. Understanding the microscopic mechanisms underlying seizures is crucial for effective epilepsy treatment, and a thorough understanding of the intricate neural circuits underlying epilepsy is vital for the development of targeted therapies and the enhancement of clinical outcomes. This review begins with an exploration of the historical evolution of techniques used in studying neural circuits related to epilepsy. It then provides an extensive overview of diverse techniques employed in this domain, discussing their fundamental principles, strengths, limitations, as well as their application. Additionally, the synthesis of multiple techniques to unveil the complexity of neural circuits is summarized. Finally, this review also presents targeted drug therapies associated with epileptic neural circuits. By providing a critical assessment of methodologies used in the study of epileptic neural circuits, this review seeks to enhance the understanding of these techniques, stimulate innovative approaches for unraveling epilepsy's complexities, and ultimately facilitate improved treatment and clinical translation for epilepsy.
Collapse
Affiliation(s)
- Wenjie Xiao
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
| | - Peile Li
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
| | - Fujiao Kong
- Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha, Hunan Province, China
| | - Jingyi Kong
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
| | - Aihua Pan
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
| | - Lili Long
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Xiaoxin Yan
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Jiaoe Gong
- Department of Neurology, Hunan Children's Hospital, Changsha, Hunan Province, China.
| | - Lily Wan
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha, Hunan Province, China.
| |
Collapse
|
8
|
Bahramnejad E, Barney ER, Lester S, Hurtado A, Thompson T, Watkins JC, Hammer MF. Greater female than male resilience to mortality and morbidity in the Scn8a mouse model of pediatric epilepsy. Int J Neurosci 2023:1-13. [PMID: 37929583 DOI: 10.1080/00207454.2023.2279497] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 10/31/2023] [Indexed: 11/07/2023]
Abstract
AIMS Females and males of all ages are affected by epilepsy; however, unlike many clinical studies, most preclinical research has focused on males. Genetic variants in the voltage-gated sodium channel gene, SCN8A, are associated with a broad spectrum of neurological and epileptic syndromes. Here we investigate sex differences in the natural history of the Scn8a-N1768D knockin mouse model of pediatric epilepsy. METHODS We utilize 24/7 video to monitor juveniles and adults of both sexes to investigate variability in seizure activity (e.g. onset and frequency), mortality and morbidity, response to cannabinoids, and mode of death. We also monitor sleep architecture using a noninvasive piezoelectric method in order to identify factors that influence seizure severity and outcome. RESULTS Both sexes had nearly 100% penetrance in seizure onset and early mortality. However, adult heterozygous (D/+) females were more resilient as exhibited by the ability to tolerate more seizures over a longer lifespan. Homozygous (D/D) juveniles did not exhibit a sex difference in overall survival. Female estrus cycle was disrupted before seizure onset, while sleep was disrupted in both sexes in association with seizure onset. Females typically died while in convulsive status epilepticus; however, a high proportion of males died while not experiencing behavioral seizures. Only juvenile and adult males benefited from cannabinoid administration. CONCLUSIONS These results support the hypothesis that factors associated with sexual differentiation play a role in the neurobiology of epilepsy and point to the importance of including both sexes in the design of studies to identify new epilepsy therapies.
Collapse
Affiliation(s)
- Erfan Bahramnejad
- Graduate Program in Pharmacology, University of Arizona, Tucson Arizona, AZ, USA
| | - Emily R Barney
- BIO5 Institute, University of Arizona, Tucson Arizona, AZ, USA
| | - Sarah Lester
- BIO5 Institute, University of Arizona, Tucson Arizona, AZ, USA
| | - Aurora Hurtado
- BIO5 Institute, University of Arizona, Tucson Arizona, AZ, USA
| | | | - Joseph C Watkins
- Department of Mathematics, University of Arizona, Tucson Arizona, AZ, USA
| | - Michael F Hammer
- BIO5 Institute, University of Arizona, Tucson Arizona, AZ, USA
- Department of Neurology, University of Arizona, Tucson Arizona, AZ, USA
| |
Collapse
|
9
|
Hostetler RE, Hu H, Agmon A. Genetically Defined Subtypes of Somatostatin-Containing Cortical Interneurons. eNeuro 2023; 10:ENEURO.0204-23.2023. [PMID: 37463742 PMCID: PMC10414551 DOI: 10.1523/eneuro.0204-23.2023] [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: 06/14/2023] [Accepted: 06/30/2023] [Indexed: 07/20/2023] Open
Abstract
Inhibitory interneurons play a crucial role in proper development and function of the mammalian cerebral cortex. Of the different inhibitory subclasses, dendritic-targeting, somatostatin-containing (SOM) interneurons may be the most diverse. Earlier studies used GFP-expressing and recombinase-expressing mouse lines to characterize genetically defined subtypes of SOM interneurons by morphologic, electrophysiological, and neurochemical properties. More recently, large-scale studies classified SOM interneurons into 13 morpho-electric transcriptomic (MET) types. It remains unclear, however, how these various classification schemes relate to each other, and experimental access to MET types has been limited by the scarcity of specific mouse driver lines. To address these issues, we crossed Flp and Cre driver lines with a dual-color intersectional reporter, allowing experimental access to several combinatorially defined SOM subsets. Brains from adult mice of both sexes were retrogradely dye labeled from the pial surface to identify layer 1-projecting neurons and immunostained against several marker proteins, revealing correlations between genetic label, axonal target, and marker protein expression in the same neurons. Lastly, using whole-cell recordings ex vivo, we analyzed and compared electrophysiological properties between different intersectional subsets. We identified two layer 1-targeting subtypes with nonoverlapping marker protein expression and electrophysiological properties, which, together with a previously characterized layer 4-targeting subtype, account for >50% of all layer 5 SOM cells and >40% of all SOM cells, and appear to map onto 5 of the 13 MET types. Genetic access to these subtypes will allow researchers to determine their synaptic inputs and outputs and uncover their roles in cortical computations and animal behavior.
Collapse
Affiliation(s)
- Rachel E Hostetler
- Department of Neuroscience, West Virginia University Rockefeller Neuroscience Institute, Morgantown, WV 26506
| | - Hang Hu
- Department of Neuroscience, West Virginia University Rockefeller Neuroscience Institute, Morgantown, WV 26506
| | - Ariel Agmon
- Department of Neuroscience, West Virginia University Rockefeller Neuroscience Institute, Morgantown, WV 26506
| |
Collapse
|
10
|
Huang TH, Lin YS, Hsiao CW, Wang LY, Ajibola MI, Abdulmajeed WI, Lin YL, Li YJ, Chen CY, Lien CC, Chiu CD, Cheng IHJ. Differential expression of GABA A receptor subunits δ and α6 mediates tonic inhibition in parvalbumin and somatostatin interneurons in the mouse hippocampus. Front Cell Neurosci 2023; 17:1146278. [PMID: 37545878 PMCID: PMC10397515 DOI: 10.3389/fncel.2023.1146278] [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: 01/17/2023] [Accepted: 06/14/2023] [Indexed: 08/08/2023] Open
Abstract
Inhibitory γ-aminobutyric acid (GABA)-ergic interneurons mediate inhibition in neuronal circuitry and support normal brain function. Consequently, dysregulation of inhibition is implicated in various brain disorders. Parvalbumin (PV) and somatostatin (SST) interneurons, the two major types of GABAergic inhibitory interneurons in the hippocampus, exhibit distinct morpho-physiological properties and coordinate information processing and memory formation. However, the molecular mechanisms underlying the specialized properties of PV and SST interneurons remain unclear. This study aimed to compare the transcriptomic differences between these two classes of interneurons in the hippocampus using the ribosome tagging approach. The results revealed distinct expressions of genes such as voltage-gated ion channels and GABAA receptor subunits between PV and SST interneurons. Gabrd and Gabra6 were identified as contributors to the contrasting tonic GABAergic inhibition observed in PV and SST interneurons. Moreover, some of the differentially expressed genes were associated with schizophrenia and epilepsy. In conclusion, our results provide molecular insights into the distinct roles of PV and SST interneurons in health and disease.
Collapse
Affiliation(s)
- Tzu-Hsuan Huang
- Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yi-Sian Lin
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Program in Genetics and Genomics, Baylor College of Medicine, Houston, TX, United States
| | - Chiao-Wan Hsiao
- Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
| | - Liang-Yun Wang
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Musa Iyiola Ajibola
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Taiwan International Graduate Program in Interdisciplinary Neuroscience, College of Life Sciences, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
| | - Wahab Imam Abdulmajeed
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Taiwan International Graduate Program in Interdisciplinary Neuroscience, College of Life Sciences, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Department of Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, University of Ilorin, Ilorin, Nigeria
| | - Yu-Ling Lin
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yu-Jui Li
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Cho-Yi Chen
- Institute of Biomedical Informatics, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Cheng-Chang Lien
- Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Institute of Neuroscience, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Taiwan International Graduate Program in Interdisciplinary Neuroscience, College of Life Sciences, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Cheng-Di Chiu
- Department of Neurosurgery, China Medical University Hospital, Taichung, Taiwan
- Spine Center, China Medical University Hospital, Taichung, Taiwan
- Graduate Institute of Biomedical Science, China Medical University, Taichung, Taiwan
- School of Medicine, China Medical University, Taichung, Taiwan
| | - Irene Han-Juo Cheng
- Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| |
Collapse
|
11
|
Wenker IC, Boscia AR, Lewis C, Tariq A, Miralles R, Hanflink JC, Saraf P, Patel MK. Forebrain epileptiform activity is not required for seizure-induced apnea in a mouse model of Scn8a epilepsy. Front Neural Circuits 2022; 16:1002013. [PMID: 36160949 PMCID: PMC9490431 DOI: 10.3389/fncir.2022.1002013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 08/19/2022] [Indexed: 11/24/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) accounts for the deaths of 8-17% of patients with epilepsy. Although the mechanisms of SUDEP are essentially unknown, one proposed mechanism is respiratory arrest initiated by a convulsive seizure. In mice, we have previously observed that extended apnea occurs during the tonic phase of seizures. Although often survived, tonic seizures became fatal when breathing did not immediately recover postictally. We also found that respiratory muscles were tonically contracted during the apnea, suggesting that muscle contraction could be the cause of apnea. In the present study, we tested the hypothesis that pyramidal neurons of the motor cortex drive motor units during the tonic phase, which produces apnea. Mice harboring the patient-derived N1768D point mutation of an Scn8a allele were crossed with transgenic mice such that inhibitory Designer Receptors Exclusively Activated by Designer Drugs (DREADD) receptors were selectively expressed in excitatory forebrain neurons. We then triggered audiogenic and hippocampal (HC) stimulated seizures under control conditions and when excitatory forebrain neurons were inhibited with the synthetic ligand Clozapine-N-Oxide (CNO). We found that inhibition with CNO was sufficient to increase seizure threshold of HC stimulated, but not audiogenic, seizures. In addition, regardless of seizure type, CNO nearly eliminated epileptiform activity that occurred proximal to the tonic phase; however, the seizure behaviors, notably the tonic phase and concomitant apnea, were unchanged. We interpret these results to indicate that while cortical neurons are likely critical for epileptogenesis and seizure initiation, the behavioral manifestations of tonic seizures are generated by neural circuitry in the mid- and/or hindbrain.
Collapse
|