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Murthy S, Nongthomba U. Role of the BCL11A/B Homologue Chronophage (Cph) in Locomotor Behaviour of Drosophila melanogaster. Neuroscience 2024; 551:1-16. [PMID: 38763224 DOI: 10.1016/j.neuroscience.2024.05.015] [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: 01/09/2024] [Revised: 05/08/2024] [Accepted: 05/13/2024] [Indexed: 05/21/2024]
Abstract
Functioning of the nervous system requires proper formation and specification of neurons as well as accurate connectivity and signalling between them. Locomotor behaviour depends upon these events that occur during neural development, and any aberration in them could result in motor disorders. Transcription factors are believed to be master regulators that control these processes, but very few linked to behaviour have been identified so far. The Drosophila homologue of BCL11A (CTIP1) and BCL11B (CTIP2), Chronophage (Cph), was recently shown to be involved in temporal patterning of neural stem cells but its role in post-mitotic neurons is not known. We show that knockdown of Cph in neurons during development results in animals with locomotor defects at both larval and adult stages. The defects are more severe in adults, with inability to stand, uncoordinated behaviour and complete loss of ability to walk, climb, or fly. These defects are similar to the motor difficulties observed in some patients with mutations in BCL11A and BCL11B. Electrophysiological recordings showed reduced evoked activity and irregular neuronal firing. All Cph-expressing neurons in the ventral nerve cord are glutamatergic. Our results imply that Cph modulates primary locomotor activity through configuration of glutamatergic neurons. Thus, this study ascribes a hitherto unknown role to Cph in locomotor behaviour of Drosophila melanogaster.
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Affiliation(s)
- Smrithi Murthy
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru 560 012, India.
| | - Upendra Nongthomba
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru 560 012, India.
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2
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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.
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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.
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3
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Sleep M, Landaverde S, Lacoste A, Tan S, Schuback R, Reiter LT, Iyengar A. Glial expression of Drosophila UBE3A causes spontaneous seizures modulated by 5-HT signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.08.579543. [PMID: 38370819 PMCID: PMC10871353 DOI: 10.1101/2024.02.08.579543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Misexpression of the E3 ubiquitin ligase UBE3A is thought to contribute to a range of neurological disorders. In the context of Dup15q syndrome, excess genomic copies of UBE3A is thought to contribute to the autism, muscle tone and spontaneous seizures characteristic of the disorder. In a Drosophila model of Dup 15q syndrome, it was recently shown glial-driven expression of the UBE3A ortholog dube3a led to a "bang-sensitive" phenotype, where mechanical shock triggers convulsions, suggesting glial dube3a expression contributes to hyperexcitability in flies. Here we directly compare the consequences of glial- and neuronal-driven dube3a expression on motor coordination and neuronal excitability in Drosophila. We utilized IowaFLI tracker and developed a hidden Markov Model to classify seizure-related immobilization. Both glial and neuronal driven dube3a expression led to clear motor phenotypes. However, only glial-driven dube3a expression displayed spontaneous immobilization events, that were exacerbated at high-temperature (38 °C). Using a tethered fly preparation we monitored flight muscle activity, we found glial-driven dube3a flies display spontaneous spike discharges which were bilaterally synchronized indicative of seizure activity. Neither control flies, nor neuronal- dube3a overexpressing flies display such firing patterns. Prior drug screen indicated bang-sensitivity in glial-driven dube3a expressing flies could be suppressed by certain 5-HT modulators. Consistent with this report, we found glial-driven dube3a flies fed the serotonin reuptake inhibitor vortioxetine and the 5HT 2A antagonist ketanserin displayed reduced immobilization and spike bursting. Together these findings highlight the potential for glial pathophysiology to drive Dup15q syndrome-related seizure activity.
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Cuddapah VA, Hsu CT, Li Y, Shah HM, Saul C, Killiany S, Shon J, Yue Z, Gionet G, Putt ME, Sehgal A. Sleepiness, not total sleep amount, increases seizure risk. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.30.560325. [PMID: 37873373 PMCID: PMC10592838 DOI: 10.1101/2023.09.30.560325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Sleep loss has been associated with increased seizure risk since antiquity. Despite this observation standing the test of time, how poor sleep drives susceptibility to seizures remains unclear. To identify underlying mechanisms, we restricted sleep in Drosophila epilepsy models and developed a method to identify spontaneous seizures using quantitative video tracking. Here we find that sleep loss exacerbates seizures but only when flies experience increased sleep need, or sleepiness , and not necessarily with reduced sleep quantity. This is supported by the paradoxical finding that acute activation of sleep-promoting circuits worsens seizures, because it increases sleep need without changing sleep amount. Sleep-promoting circuits become hyperactive after sleep loss and are associated with increased whole-brain activity. During sleep restriction, optogenetic inhibition of sleep-promoting circuits to reduce sleepiness protects against seizures. Downregulation of the 5HT1A serotonin receptor in sleep-promoting cells mediates the effect of sleep need on seizures, and we identify an FDA-approved 5HT1A agonist to mitigate seizures. Our findings demonstrate that while homeostatic sleep is needed to recoup lost sleep, it comes at the cost of increasing seizure susceptibility. We provide an unexpected perspective on interactions between sleep and seizures, and surprisingly implicate sleep- promoting circuits as a therapeutic target for seizure control.
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Tepe B, Macke EL, Niceta M, Weisz Hubshman M, Kanca O, Schultz-Rogers L, Zarate YA, Schaefer GB, Granadillo De Luque JL, Wegner DJ, Cogne B, Gilbert-Dussardier B, Le Guillou X, Wagner EJ, Pais LS, Neil JE, Mochida GH, Walsh CA, Magal N, Drasinover V, Shohat M, Schwab T, Schmitz C, Clark K, Fine A, Lanpher B, Gavrilova R, Blanc P, Burglen L, Afenjar A, Steel D, Kurian MA, Prabhakar P, Gößwein S, Di Donato N, Bertini ES, Wangler MF, Yamamoto S, Tartaglia M, Klee EW, Bellen HJ. Bi-allelic variants in INTS11 are associated with a complex neurological disorder. Am J Hum Genet 2023; 110:774-789. [PMID: 37054711 PMCID: PMC10183469 DOI: 10.1016/j.ajhg.2023.03.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 03/18/2023] [Indexed: 04/15/2023] Open
Abstract
The Integrator complex is a multi-subunit protein complex that regulates the processing of nascent RNAs transcribed by RNA polymerase II (RNAPII), including small nuclear RNAs, enhancer RNAs, telomeric RNAs, viral RNAs, and protein-coding mRNAs. Integrator subunit 11 (INTS11) is the catalytic subunit that cleaves nascent RNAs, but, to date, mutations in this subunit have not been linked to human disease. Here, we describe 15 individuals from 10 unrelated families with bi-allelic variants in INTS11 who present with global developmental and language delay, intellectual disability, impaired motor development, and brain atrophy. Consistent with human observations, we find that the fly ortholog of INTS11, dIntS11, is essential and expressed in the central nervous systems in a subset of neurons and most glia in larval and adult stages. Using Drosophila as a model, we investigated the effect of seven variants. We found that two (p.Arg17Leu and p.His414Tyr) fail to rescue the lethality of null mutants, indicating that they are strong loss-of-function variants. Furthermore, we found that five variants (p.Gly55Ser, p.Leu138Phe, p.Lys396Glu, p.Val517Met, and p.Ile553Glu) rescue lethality but cause a shortened lifespan and bang sensitivity and affect locomotor activity, indicating that they are partial loss-of-function variants. Altogether, our results provide compelling evidence that integrity of the Integrator RNA endonuclease is critical for brain development.
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Affiliation(s)
- Burak Tepe
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Erica L Macke
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Marcello Niceta
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Monika Weisz Hubshman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | | | - Yuri A Zarate
- Division of Genetics and Metabolism, University of Kentucky, Lexington, KY, USA
| | - G Bradley Schaefer
- Section of Genetics and Metabolism, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Jorge Luis Granadillo De Luque
- Division of Genetics and Genomic Medicine, Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Daniel J Wegner
- Edward Mallinckrodt Department of Pediatrics, Washington University in St. Louis School of Medicine and St. Louis Children's Hospital, St. Louis, Missouri, USA
| | - Benjamin Cogne
- Laboratory of Molecular Genetics, CHU de Nantes, Nantes, France
| | | | | | - Eric J Wagner
- Department of Biochemistry and Biophysics, Center for RNA Biology, University of Rochester School of Medicine, Rochester, NY 14642, USA
| | - Lynn S Pais
- Division of Genetics and Genomics, and Howard Hughes Medical Institute, Boston Children's Hospital, and Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA, USA; Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Jennifer E Neil
- Division of Genetics and Genomics, and Howard Hughes Medical Institute, Boston Children's Hospital, and Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA, USA
| | - Ganeshwaran H Mochida
- Division of Genetics and Genomics, and Howard Hughes Medical Institute, Boston Children's Hospital, and Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, and Howard Hughes Medical Institute, Boston Children's Hospital, and Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA, USA
| | - Nurit Magal
- The Raphael Recanati Genetic Institute, Rabin Medical Center, Petach Tikva, Israel
| | - Valerie Drasinover
- The Raphael Recanati Genetic Institute, Rabin Medical Center, Petach Tikva, Israel
| | - Mordechai Shohat
- Cancer Research Center, Chaim Sheba Medical Center, Ramat Gan, Israel; Medical Genetics Institute of Maccabi HMO, Rechovot, Israel
| | - Tanya Schwab
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Chris Schmitz
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Karl Clark
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Anthony Fine
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Brendan Lanpher
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
| | - Ralitza Gavrilova
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
| | - Pierre Blanc
- APHP, Département de génétique, Sorbonne Université, GRC n°19, ConCer-LD, Centre de Référence déficiences intellectuelles de causes rares, Hôpital Armand Trousseau, 75012 Paris, France
| | - Lydie Burglen
- APHP, Département de génétique, Sorbonne Université, GRC n°19, ConCer-LD, Centre de Référence déficiences intellectuelles de causes rares, Hôpital Armand Trousseau, 75012 Paris, France
| | - Alexandra Afenjar
- APHP. SU, Centre de Référence Malformations et maladies congénitales du cervelet, département de génétique et embryologie médicale, Hôpital Trousseau, 75012 Paris, France
| | - Dora Steel
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, UCL Great Ormond Street Institute of Child Health, London, UK; Department of Neurology, Great Ormond Street Hospital for Children, London, UK
| | - Manju A Kurian
- Developmental Neurosciences, Zayed Centre for Research into Rare Disease in Children, UCL Great Ormond Street Institute of Child Health, London, UK; Department of Neurology, Great Ormond Street Hospital for Children, London, UK
| | - Prab Prabhakar
- Department of Neurology, Great Ormond Street Hospital for Children, London, UK
| | - Sophie Gößwein
- Institute for Clinical Genetics, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
| | - Nataliya Di Donato
- Institute for Clinical Genetics, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden, Germany
| | - Enrico S Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Michael F Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Marco Tartaglia
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Eric W Klee
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA; Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
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6
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Co-dependent regulation of p-BRAF and potassium channel KCNMA1 levels drives glioma progression. Cell Mol Life Sci 2023; 80:61. [PMID: 36763212 PMCID: PMC9918570 DOI: 10.1007/s00018-023-04708-9] [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: 10/07/2022] [Revised: 01/03/2023] [Accepted: 01/23/2023] [Indexed: 02/11/2023]
Abstract
BRAF mutations have been found in gliomas which exhibit abnormal electrophysiological activities, implying their potential links with the ion channel functions. In this study, we identified the Drosophila potassium channel, Slowpoke (Slo), the ortholog of human KCNMA1, as a critical factor involved in dRafGOF glioma progression. Slo was upregulated in dRafGOF glioma. Knockdown of slo led to decreases in dRafGOF levels, glioma cell proliferation, and tumor-related phenotypes. Overexpression of slo in glial cells elevated dRaf expression and promoted cell proliferation. Similar mutual regulations of p-BRAF and KCNMA1 levels were then recapitulated in human glioma cells with the BRAF mutation. Elevated p-BRAF and KCNMA1 were also observed in HEK293T cells upon the treatment of 20 mM KCl, which causes membrane depolarization. Knockdown KCNMA1 in these cells led to a further decrease in cell viability. Based on these results, we conclude that the levels of p-BRAF and KCNMA1 are co-dependent and mutually regulated. We propose that, in depolarized glioma cells with BRAF mutations, high KCNMA1 levels act to repolarize membrane potential and facilitate cell growth. Our study provides a new strategy to antagonize the progression of gliomas as induced by BRAF mutations.
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Fischer FP, Karge RA, Weber YG, Koch H, Wolking S, Voigt A. Drosophila melanogaster as a versatile model organism to study genetic epilepsies: An overview. Front Mol Neurosci 2023; 16:1116000. [PMID: 36873106 PMCID: PMC9978166 DOI: 10.3389/fnmol.2023.1116000] [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: 12/04/2022] [Accepted: 01/23/2023] [Indexed: 02/18/2023] Open
Abstract
Epilepsy is one of the most prevalent neurological disorders, affecting more than 45 million people worldwide. Recent advances in genetic techniques, such as next-generation sequencing, have driven genetic discovery and increased our understanding of the molecular and cellular mechanisms behind many epilepsy syndromes. These insights prompt the development of personalized therapies tailored to the genetic characteristics of an individual patient. However, the surging number of novel genetic variants renders the interpretation of pathogenetic consequences and of potential therapeutic implications ever more challenging. Model organisms can help explore these aspects in vivo. In the last decades, rodent models have significantly contributed to our understanding of genetic epilepsies but their establishment is laborious, expensive, and time-consuming. Additional model organisms to investigate disease variants on a large scale would be desirable. The fruit fly Drosophila melanogaster has been used as a model organism in epilepsy research since the discovery of "bang-sensitive" mutants more than half a century ago. These flies respond to mechanical stimulation, such as a brief vortex, with stereotypic seizures and paralysis. Furthermore, the identification of seizure-suppressor mutations allows to pinpoint novel therapeutic targets. Gene editing techniques, such as CRISPR/Cas9, are a convenient way to generate flies carrying disease-associated variants. These flies can be screened for phenotypic and behavioral abnormalities, shifting of seizure thresholds, and response to anti-seizure medications and other substances. Moreover, modification of neuronal activity and seizure induction can be achieved using optogenetic tools. In combination with calcium and fluorescent imaging, functional alterations caused by mutations in epilepsy genes can be traced. Here, we review Drosophila as a versatile model organism to study genetic epilepsies, especially as 81% of human epilepsy genes have an orthologous gene in Drosophila. Furthermore, we discuss newly established analysis techniques that might be used to further unravel the pathophysiological aspects of genetic epilepsies.
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Affiliation(s)
- Florian P Fischer
- Department of Epileptology and Neurology, RWTH Aachen University, Aachen, Germany
| | - Robin A Karge
- Department of Epileptology and Neurology, RWTH Aachen University, Aachen, Germany
| | - Yvonne G Weber
- Department of Epileptology and Neurology, RWTH Aachen University, Aachen, Germany.,Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany
| | - Henner Koch
- Department of Epileptology and Neurology, RWTH Aachen University, Aachen, Germany
| | - Stefan Wolking
- Department of Epileptology and Neurology, RWTH Aachen University, Aachen, Germany
| | - Aaron Voigt
- Department of Neurology, RWTH Aachen University, Aachen, Germany.,JARA-BRAIN Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich GmbH and RWTH Aachen University, Aachen, Germany
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8
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Lu S, Ma M, Mao X, Bacino CA, Jankovic J, Sutton VR, Bartley JA, Wang X, Rosenfeld JA, Beleza-Meireles A, Chauhan J, Pan X, Li M, Liu P, Prescott K, Amin S, Davies G, Wangler MF, Dai Y, Bellen HJ. De novo variants in FRMD5 are associated with developmental delay, intellectual disability, ataxia, and abnormalities of eye movement. Am J Hum Genet 2022; 109:1932-1943. [PMID: 36206744 PMCID: PMC9606480 DOI: 10.1016/j.ajhg.2022.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 09/09/2022] [Indexed: 01/25/2023] Open
Abstract
Proteins containing the FERM (four-point-one, ezrin, radixin, and moesin) domain link the plasma membrane with cytoskeletal structures at specific cellular locations and have been implicated in the localization of cell-membrane-associated proteins and/or phosphoinositides. FERM domain-containing protein 5 (FRMD5) localizes at cell adherens junctions and stabilizes cell-cell contacts. To date, variants in FRMD5 have not been associated with a Mendelian disease in OMIM. Here, we describe eight probands with rare heterozygous missense variants in FRMD5 who present with developmental delay, intellectual disability, ataxia, seizures, and abnormalities of eye movement. The variants are de novo in all for whom parental testing was available (six out of eight probands), and human genetic datasets suggest that FRMD5 is intolerant to loss of function (LoF). We found that the fly ortholog of FRMD5, CG5022 (dFrmd), is expressed in the larval and adult central nervous systems where it is present in neurons but not in glia. dFrmd LoF mutant flies are viable but are extremely sensitive to heat shock, which induces severe seizures. The mutants also exhibit defective responses to light. The human FRMD5 reference (Ref) cDNA rescues the fly dFrmd LoF phenotypes. In contrast, all the FRMD5 variants tested in this study (c.340T>C, c.1051A>G, c.1053C>G, c.1054T>C, c.1045A>C, and c.1637A>G) behave as partial LoF variants. In addition, our results indicate that two variants that were tested have dominant-negative effects. In summary, the evidence supports that the observed variants in FRMD5 cause neurological symptoms in humans.
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Affiliation(s)
- Shenzhao Lu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Mengqi Ma
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Xiao Mao
- National Health Commission Key Laboratory for Birth Defect Research and Prevention, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan 410008, China; Department of Medical Genetics, Maternal and Child Health Hospital of Hunan Province, Changsha, Hunan 410008, China
| | - Carlos A Bacino
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - Joseph Jankovic
- Parkinson's Disease Center and Movement Disorders Clinic, Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - James A Bartley
- Loma Linda University Children's Hospital, Loma Linda, CA 92354, USA
| | - Xueying Wang
- Department of Pediatrics, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710004, China
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics Laboratories, Houston, TX 77021, USA
| | - Ana Beleza-Meireles
- Clinical Genetics Department, St Michael's Hospital, University Hospitals Bristol and Weston, Bristol BS1 3NU, UK
| | - Jaynee Chauhan
- Yorkshire Regional Genetics Service, Leeds Teaching Hospitals NHS Trust, Chapel Allerton Hospital, Leeds LS7 4SA, UK
| | - Xueyang Pan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Megan Li
- Invitae, San Francisco, CA 94103, USA
| | - Pengfei Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Baylor Genetics Laboratories, Houston, TX 77021, USA
| | - Katrina Prescott
- Yorkshire Regional Genetics Service, Leeds Teaching Hospitals NHS Trust, Chapel Allerton Hospital, Leeds LS7 4SA, UK
| | - Sam Amin
- Paediatric Neurology Department, Bristol Royal Pediatric Hospital, University Hospitals Bristol and Weston, Bristol BS1 3NU, UK
| | | | - Michael F Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Texas Children's Hospital, Houston, TX 77030, USA
| | - Yuwei Dai
- National Health Commission Key Laboratory for Birth Defect Research and Prevention, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan 410008, China; Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
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9
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Lu S, Hernan R, Marcogliese PC, Huang Y, Gertler TS, Akcaboy M, Liu S, Chung HL, Pan X, Sun X, Oguz MM, Oztoprak U, de Baaij JH, Ivanisevic J, McGinnis E, Guillen Sacoto MJ, Chung WK, Bellen HJ. Loss-of-function variants in TIAM1 are associated with developmental delay, intellectual disability, and seizures. Am J Hum Genet 2022; 109:571-586. [PMID: 35240055 DOI: 10.1016/j.ajhg.2022.01.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 01/27/2022] [Indexed: 12/13/2022] Open
Abstract
TIAM Rac1-associated GEF 1 (TIAM1) regulates RAC1 signaling pathways that affect the control of neuronal morphogenesis and neurite outgrowth by modulating the actin cytoskeletal network. To date, TIAM1 has not been associated with a Mendelian disorder. Here, we describe five individuals with bi-allelic TIAM1 missense variants who have developmental delay, intellectual disability, speech delay, and seizures. Bioinformatic analyses demonstrate that these variants are rare and likely pathogenic. We found that the Drosophila ortholog of TIAM1, still life (sif), is expressed in larval and adult central nervous system (CNS) and is mainly expressed in a subset of neurons, but not in glia. Loss of sif reduces the survival rate, and the surviving adults exhibit climbing defects, are prone to severe seizures, and have a short lifespan. The TIAM1 reference (Ref) cDNA partially rescues the sif loss-of-function (LoF) phenotypes. We also assessed the function associated with three TIAM1 variants carried by two of the probands and compared them to the TIAM1 Ref cDNA function in vivo. TIAM1 p.Arg23Cys has reduced rescue ability when compared to TIAM1 Ref, suggesting that it is a partial LoF variant. In ectopic expression studies, both wild-type sif and TIAM1 Ref are toxic, whereas the three variants (p.Leu862Phe, p.Arg23Cys, and p.Gly328Val) show reduced toxicity, suggesting that they are partial LoF variants. In summary, we provide evidence that sif is important for appropriate neural function and that TIAM1 variants observed in the probands are disruptive, thus implicating loss of TIAM1 in neurological phenotypes in humans.
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10
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Cho TS, Beigaitė E, Klein NE, Sweeney ST, Bhattacharya MRC. The Putative Drosophila TMEM184B Ortholog Tmep Ensures Proper Locomotion by Restraining Ectopic Firing at the Neuromuscular Junction. Mol Neurobiol 2022; 59:2605-2619. [PMID: 35107803 PMCID: PMC9018515 DOI: 10.1007/s12035-022-02760-3] [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: 09/13/2021] [Accepted: 01/20/2022] [Indexed: 11/29/2022]
Abstract
TMEM184B is a putative seven-pass membrane protein that promotes axon degeneration after injury. TMEM184B mutation causes aberrant neuromuscular architecture and sensory and motor behavioral defects in mice. The mechanism through which TMEM184B causes neuromuscular defects is unknown. We employed Drosophila melanogaster to investigate the function of the closely related gene, Tmep (CG12004), at the neuromuscular junction. We show that Tmep is required for full adult viability and efficient larval locomotion. Tmep mutant larvae have a reduced body contraction rate compared to controls, with stronger deficits in females. In recordings from body wall muscles, Tmep mutants show substantial hyperexcitability, with many postsynaptic potentials fired in response to a single stimulation, consistent with a role for Tmep in restraining synaptic excitability. Additional branches and satellite boutons at Tmep mutant neuromuscular junctions are consistent with an activity-dependent synaptic overgrowth. Tmep is expressed in endosomes and synaptic vesicles within motor neurons, suggesting a possible role in synaptic membrane trafficking. Using RNAi knockdown, we show that Tmep is required in motor neurons for proper larval locomotion and excitability, and that its reduction increases levels of presynaptic calcium. Locomotor defects can be rescued by presynaptic knockdown of endoplasmic reticulum calcium channels or by reducing evoked release probability, further suggesting that excess synaptic activity drives behavioral deficiencies. Our work establishes a critical function for Tmep in the regulation of synaptic transmission and locomotor behavior.
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Affiliation(s)
- Tiffany S Cho
- Department of Neuroscience, University of Arizona, 1040 E 4th Street, Tucson, AZ, 85721, USA
| | - Eglė Beigaitė
- Department of Biology, University of York, York, YO10 5DD, UK.,York Biomedical Research Institute, University of York, York, YO10 5DD, UK
| | - Nathaniel E Klein
- Department of Neuroscience, University of Arizona, 1040 E 4th Street, Tucson, AZ, 85721, USA
| | - Sean T Sweeney
- Department of Biology, University of York, York, YO10 5DD, UK.,York Biomedical Research Institute, University of York, York, YO10 5DD, UK
| | - Martha R C Bhattacharya
- Department of Neuroscience, University of Arizona, 1040 E 4th Street, Tucson, AZ, 85721, USA.
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11
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Abstract
Hypersynchronous neural activity is a characteristic feature of seizures. Although many Drosophila mutants of epilepsy-related genes display clear behavioral spasms and motor unit hyperexcitability, field potential measurements of aberrant hypersynchronous activity across brain regions during seizures have yet to be described. Here, we report a straightforward method to observe local field potentials (LFPs) from the Drosophila brain to monitor ensemble neural activity during seizures in behaving tethered flies. High frequency stimulation across the brain reliably triggers a stereotypic sequence of electroconvulsive seizure (ECS) spike discharges readily detectable in the dorsal longitudinal muscle (DLM) and coupled with behavioral spasms. During seizure episodes, the LFP signal displayed characteristic large-amplitude oscillations with a stereotypic temporal correlation to DLM flight muscle spiking. ECS-related LFP events were clearly distinct from rest- and flight-associated LFP patterns. We further characterized the LFP activity during different types of seizures originating from genetic and pharmacological manipulations. In the 'bang-sensitive' sodium channel mutant bangsenseless (bss), the LFP pattern was prolonged, and the temporal correlation between LFP oscillations and DLM discharges was altered. Following administration of the pro-convulsant GABAA blocker picrotoxin, we uncovered a qualitatively different LFP activity pattern, which consisted of a slow (1-Hz), repetitive, waveform, closely coupled with DLM bursting and behavioral spasms. Our approach to record brain LFPs presents an initial framework for electrophysiological analysis of the complex brain-wide activity patterns in the large collection of Drosophila excitability mutants.
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Affiliation(s)
- Atulya Iyengar
- Department of Biology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA
| | - Chun-Fang Wu
- Department of Biology, and Iowa Neuroscience Institute, University of Iowa, Iowa City, IA, USA
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12
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Characterization of Seizure Induction Methods in Drosophila. eNeuro 2021; 8:ENEURO.0079-21.2021. [PMID: 34330816 PMCID: PMC8387149 DOI: 10.1523/eneuro.0079-21.2021] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/02/2021] [Accepted: 06/10/2021] [Indexed: 02/07/2023] Open
Abstract
Epilepsy is one of the most common neurologic disorders. Around one third of patients do not respond to current medications. This lack of treatment indicates a need for better understanding of the underlying mechanisms and, importantly, the identification of novel targets for drug manipulation. The fruit fly Drosophila melanogaster has a fast reproduction time, powerful genetics, and facilitates large sample sizes, making it a strong model of seizure mechanisms. To better understand behavioral and physiological phenotypes across major fly seizure genotypes we systematically measured seizure severity and secondary behavioral phenotypes at both the larval and adult stage. Comparison of several seizure-induction methods; specifically electrical, mechanical and heat induction, show that larval electroshock is the most effective at inducing seizures across a wide range of seizure-prone mutants tested. Locomotion in adults and larvae was found to be non-predictive of seizure susceptibility. Recording activity in identified larval motor neurons revealed variations in action potential (AP) patterns, across different genotypes, but these patterns did not correlate with seizure susceptibility. To conclude, while there is wide variation in mechanical induction, heat induction, and secondary phenotypes, electroshock is the most consistent method of seizure induction across known major seizure genotypes in Drosophila.
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13
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Abstract
One in three epilepsy cases is drug resistant, and seizures often begin in infancy, when they are life-threatening and when therapeutic options are highly limited. An important tool for prioritizing and validating genes associated with epileptic conditions, which is suitable for large-scale screening, is disease modeling in Drosophila. Approximately two-thirds of disease genes are conserved in Drosophila, and gene-specific fly models exhibit behavioral changes that are related to symptoms of epilepsy. Models are based on behavior readouts, seizure-like attacks and paralysis following stimulation, and neuronal, cell-biological readouts that are in the majority based on changes in nerve cell activity or morphology. In this review, we focus on behavioral phenotypes. Importantly, Drosophila modeling is independent of, and complementary to, other approaches that are computational and based on systems analysis. The large number of known epilepsy-associated gene variants indicates a need for efficient research strategies. We will discuss the status quo of epilepsy disease modelling in Drosophila and describe promising steps towards the development of new drugs to reduce seizure rates and alleviate other epileptic symptoms.
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Affiliation(s)
- Paul Lasko
- Department of Human Genetics, Radboud University Medical Centre, Nijmegen, Netherlands
- Department of Biology, McGill University, Montréal, Québec, Canada
| | - Kevin Lüthy
- Department of Human Genetics, Radboud University Medical Centre, Nijmegen, Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, Netherlands
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14
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Muir AM, Cohen JL, Sheppard SE, Guttipatti P, Lo TY, Weed N, Doherty D, DeMarzo D, Fagerberg CR, Kjærsgaard L, Larsen MJ, Rump P, Löhner K, Hirsch Y, Zeevi DA, Zackai EH, Bhoj E, Song Y, Mefford HC. Bi-allelic Loss-of-Function Variants in NUP188 Cause a Recognizable Syndrome Characterized by Neurologic, Ocular, and Cardiac Abnormalities. Am J Hum Genet 2020; 106:623-631. [PMID: 32275884 PMCID: PMC7212259 DOI: 10.1016/j.ajhg.2020.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 03/11/2020] [Indexed: 02/08/2023] Open
Abstract
Nucleoporins (NUPs) are an essential component of the nuclear-pore complex, which regulates nucleocytoplasmic transport of macromolecules. Pathogenic variants in NUP genes have been linked to several inherited human diseases, including a number with progressive neurological degeneration. We present six affected individuals with bi-allelic truncating variants in NUP188 and strikingly similar phenotypes and clinical courses, representing a recognizable genetic syndrome; the individuals are from four unrelated families. Key clinical features include congenital cataracts, hypotonia, prenatal-onset ventriculomegaly, white-matter abnormalities, hypoplastic corpus callosum, congenital heart defects, and central hypoventilation. Characteristic dysmorphic features include small palpebral fissures, a wide nasal bridge and nose, micrognathia, and digital anomalies. All affected individuals died as a result of respiratory failure, and five of them died within the first year of life. Nuclear import of proteins was decreased in affected individuals' fibroblasts, supporting a possible disease mechanism. CRISPR-mediated knockout of NUP188 in Drosophila revealed motor deficits and seizure susceptibility, partially recapitulating the neurological phenotype seen in affected individuals. Removal of NUP188 also resulted in aberrant dendrite tiling, suggesting a potential role of NUP188 in dendritic development. Two of the NUP188 pathogenic variants are enriched in the Ashkenazi Jewish population in gnomAD, a finding we confirmed with a separate targeted population screen of an international sampling of 3,225 healthy Ashkenazi Jewish individuals. Taken together, our results implicate bi-allelic loss-of-function NUP188 variants in a recessive syndrome characterized by a distinct neurologic, ophthalmologic, and facial phenotype.
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Affiliation(s)
- Alison M Muir
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195, USA
| | - Jennifer L Cohen
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Sarah E Sheppard
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Pavithran Guttipatti
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Tsz Y Lo
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Natalie Weed
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195, USA
| | - Dan Doherty
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195, USA; Seattle Children's Hospital, Seattle, WA 98105, USA; Brotman Baty Institute for Precision Medicine, Seattle, WA 98195, USA
| | - Danielle DeMarzo
- Department of Pediatrics, University of Oklahoma, Oklahoma City, OK 73104, USA
| | | | - Lars Kjærsgaard
- Hans Christian Andersen Children's Hospital, Odense University Hospital, Denmark
| | - Martin J Larsen
- Department of Clinical Genetics, Odense University Hospital, Denmark
| | - Patrick Rump
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Katharina Löhner
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Yoel Hirsch
- The Committee for Prevention of Jewish Genetic Diseases, Dor Yeshorim, Jerusalem, Israel
| | - David A Zeevi
- The Committee for Prevention of Jewish Genetic Diseases, Dor Yeshorim, Jerusalem, Israel
| | - Elaine H Zackai
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Elizabeth Bhoj
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Yuanquan Song
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Heather C Mefford
- Department of Pediatrics, Division of Genetic Medicine, University of Washington, Seattle, WA 98195, USA; Seattle Children's Hospital, Seattle, WA 98105, USA; Brotman Baty Institute for Precision Medicine, Seattle, WA 98195, USA.
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15
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Chi W, Iyengar ASR, Albersen M, Bosma M, Verhoeven-Duif NM, Wu CF, Zhuang X. Pyridox (am) ine 5'-phosphate oxidase deficiency induces seizures in Drosophila melanogaster. Hum Mol Genet 2020; 28:3126-3136. [PMID: 31261385 DOI: 10.1093/hmg/ddz143] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/31/2019] [Accepted: 06/04/2019] [Indexed: 12/12/2022] Open
Abstract
Pyridox (am) ine 5'-phosphate oxidase (PNPO) is a rate-limiting enzyme in converting dietary vitamin B6 (VB6) to pyridoxal 5'-phosphate (PLP), the biologically active form of VB6 and involved in the synthesis of neurotransmitters including γ-aminobutyric acid (GABA), dopamine, and serotonin. In humans, PNPO mutations have been increasingly identified in neonatal epileptic encephalopathy and more recently also in early-onset epilepsy. Till now, little is known about the neurobiological mechanisms underlying PNPO-deficiency-induced seizures due to the lack of animal models. Previously, we identified a c.95 C>A missense mutation in sugarlethal (sgll)-the Drosophila homolog of human PNPO (hPNPO)-and found mutant (sgll95) flies exhibiting a lethal phenotype on a diet devoid of VB6. Here, we report the establishment of both sgll95 and ubiquitous sgll knockdown (KD) flies as valid animal models of PNPO-deficiency-induced epilepsy. Both sgll95 and sgll KD flies exhibit spontaneous seizures before they die. Electrophysiological recordings reveal that seizures caused by PNPO deficiency have characteristics similar to that in flies treated with the GABA antagonist picrotoxin. Both seizures and lethality are associated with low PLP levels and can be rescued by ubiquitous expression of wild-type sgll or hPNPO, suggesting the functional conservation of the PNPO enzyme between humans and flies. Results from cell type-specific sgll KD further demonstrate that PNPO in the brain is necessary for seizure prevention and survival. Our establishment of the first animal model of PNPO deficiency will lead to better understanding of VB6 biology, the PNPO gene and its mutations discovered in patients, and can be a cost-effective system to test therapeutic strategies.
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Affiliation(s)
- Wanhao Chi
- Committee on Genetics, Genomics and Systems Biology.,Department of Neurobiology, University of Chicago, Chicago, IL, USA
| | - Atulya S R Iyengar
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA, USA
| | - Monique Albersen
- Section Metabolic Diagnostics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, EA, The Netherlands
| | - Marjolein Bosma
- Section Metabolic Diagnostics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, EA, The Netherlands
| | - Nanda M Verhoeven-Duif
- Section Metabolic Diagnostics, Department of Medical Genetics, University Medical Center Utrecht, Utrecht, EA, The Netherlands
| | - Chun-Fang Wu
- Department of Biology, College of Liberal Arts and Sciences, University of Iowa, Iowa City, IA, USA
| | - Xiaoxi Zhuang
- Department of Neurobiology, University of Chicago, Chicago, IL, USA
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16
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Parkinson's disease-associated iPLA2-VIA/PLA2G6 regulates neuronal functions and α-synuclein stability through membrane remodeling. Proc Natl Acad Sci U S A 2019; 116:20689-20699. [PMID: 31548400 PMCID: PMC6789907 DOI: 10.1073/pnas.1902958116] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The mechanisms of α-synuclein aggregation and subsequent Lewy body formation are a key pathogenesis of Parkinson’s disease (PD). PARK14-linked PD, which is caused by mutations of the iPLA2-VIA/PLA2G6 gene, exhibits a marked Lewy body pathology. iPLA2-VIA, which belongs to the phospholipase A2 family, is another causative gene of neurodegeneration with brain iron accumulation (NBIA). Here, we demonstrate that iPLA2-VIA loss results in acyl-chain shortening in phospholipids, which affects ER homeostasis and neurotransmission and promotes α-synuclein aggregation. The administration of linoleic acid or the overexpression of C19orf12, one of the NBIA-causative genes, also suppresses the acyl-chain shortening by iPLA2-VIA loss. The rescue of iPLA2-VIA phenotypes by C19orf12 provides significant molecular insight into the underlying common pathogenesis of PD and NBIA. Mutations in the iPLA2-VIA/PLA2G6 gene are responsible for PARK14-linked Parkinson’s disease (PD) with α-synucleinopathy. However, it is unclear how iPLA2-VIA mutations lead to α-synuclein (α-Syn) aggregation and dopaminergic (DA) neurodegeneration. Here, we report that iPLA2-VIA–deficient Drosophila exhibits defects in neurotransmission during early developmental stages and progressive cell loss throughout the brain, including degeneration of the DA neurons. Lipid analysis of brain tissues reveals that the acyl-chain length of phospholipids is shortened by iPLA2-VIA loss, which causes endoplasmic reticulum (ER) stress through membrane lipid disequilibrium. The introduction of wild-type human iPLA2-VIA or the mitochondria–ER contact site-resident protein C19orf12 in iPLA2-VIA–deficient flies rescues the phenotypes associated with altered lipid composition, ER stress, and DA neurodegeneration, whereas the introduction of a disease-associated missense mutant, iPLA2-VIA A80T, fails to suppress these phenotypes. The acceleration of α-Syn aggregation by iPLA2-VIA loss is suppressed by the administration of linoleic acid, correcting the brain lipid composition. Our findings suggest that membrane remodeling by iPLA2-VIA is required for the survival of DA neurons and α-Syn stability.
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17
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Hill AS, Jain P, Folan NE, Ben-Shahar Y. The Drosophila ERG channel seizure plays a role in the neuronal homeostatic stress response. PLoS Genet 2019; 15:e1008288. [PMID: 31393878 PMCID: PMC6687100 DOI: 10.1371/journal.pgen.1008288] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 07/04/2019] [Indexed: 11/24/2022] Open
Abstract
Neuronal physiology is particularly sensitive to acute stressors that affect excitability, many of which can trigger seizures and epilepsies. Although intrinsic neuronal homeostasis plays an important role in maintaining overall nervous system robustness and its resistance to stressors, the specific genetic and molecular mechanisms that underlie these processes are not well understood. Here we used a reverse genetic approach in Drosophila to test the hypothesis that specific voltage-gated ion channels contribute to neuronal homeostasis, robustness, and stress resistance. We found that the activity of the voltage-gated potassium channel seizure (sei), an ortholog of the mammalian ERG channel family, is essential for protecting flies from acute heat-induced seizures. Although sei is broadly expressed in the nervous system, our data indicate that its impact on the organismal robustness to acute environmental stress is primarily mediated via its action in excitatory neurons, the octopaminergic system, as well as neuropile ensheathing and perineurial glia. Furthermore, our studies suggest that human mutations in the human ERG channel (hERG), which have been primarily implicated in the cardiac Long QT Syndrome (LQTS), may also contribute to the high incidence of seizures in LQTS patients via a cardiovascular-independent neurogenic pathway.
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Affiliation(s)
- Alexis S. Hill
- Department of Biology, College of the Holy Cross, Worcester, Massachusetts, United States of America
| | - Poorva Jain
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Nicole E. Folan
- Department of Biology, College of the Holy Cross, Worcester, Massachusetts, United States of America
| | - Yehuda Ben-Shahar
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, United States of America
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18
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Kasuya J, Iyengar A, Chen HL, Lansdon P, Wu CF, Kitamoto T. Milk-whey diet substantially suppresses seizure-like phenotypes of paraShu, a Drosophila voltage-gated sodium channel mutant. J Neurogenet 2019; 33:164-178. [PMID: 31096839 DOI: 10.1080/01677063.2019.1597082] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The Drosophila mutant paraShu harbors a dominant, gain-of-function allele of the voltage-gated sodium channel gene, paralytic (para). The mutant flies display severe seizure-like phenotypes, including neuronal hyperexcitability, spontaneous spasms, ether-induced leg shaking, and heat-induced convulsions. We unexpectedly found that two distinct food recipes used routinely in the Drosophila research community result in a striking difference in severity of the paraShu phenotypes. Namely, when paraShu mutants were raised on the diet originally formulated by Edward Lewis in 1960, they showed severe neurological defects as previously reported. In contrast, when they were raised on the diet developed by Frankel and Brousseau in 1968, these phenotypes were substantially suppressed. Comparison of the effects of these two well-established food recipes revealed that the diet-dependent phenotypic suppression is accounted for by milk whey, which is present only in the latter. Inclusion of milk whey in the diet during larval stages was critical for suppression of the adult paraShu phenotypes, suggesting that this dietary modification affects development of the nervous system. We also found that milk whey has selective effects on other neurological mutants. Among the behavioral phenotypes of different para mutant alleles, those of paraGEFS+ and parabss were suppressed by milk whey, while those of paraDS and parats1 were not significantly affected. Overall, our study demonstrates that different diets routinely used in Drosophila labs could have considerably different effects on neurological phenotypes of Drosophila mutants. This finding provides a solid foundation for further investigation into how dietary modifications affect development and function of the nervous system and, ultimately, how they influence behavior.
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Affiliation(s)
- Junko Kasuya
- a Department of Anesthesia, Carver College of Medicine , University of Iowa , Iowa city , IA , USA
| | - Atulya Iyengar
- b Department of Biology, College of Liberal Arts and Sciences , University of Iowa , Iowa city , IA , USA.,c Interdisciplinary Graduate Program in Neuroscience , University of Iowa , Iowa city , IA , USA
| | - Hung-Lin Chen
- d Department of Medical Research , Tung's Taichung MetroHarbor Hospital , Taichung , Taiwan 43503 , ROC
| | - Patrick Lansdon
- e Interdisciplinary Graduate Program in Genetics , University of Iowa , Iowa city , IA , USA
| | - Chun-Fang Wu
- b Department of Biology, College of Liberal Arts and Sciences , University of Iowa , Iowa city , IA , USA.,c Interdisciplinary Graduate Program in Neuroscience , University of Iowa , Iowa city , IA , USA.,e Interdisciplinary Graduate Program in Genetics , University of Iowa , Iowa city , IA , USA
| | - Toshihiro Kitamoto
- a Department of Anesthesia, Carver College of Medicine , University of Iowa , Iowa city , IA , USA.,c Interdisciplinary Graduate Program in Neuroscience , University of Iowa , Iowa city , IA , USA.,e Interdisciplinary Graduate Program in Genetics , University of Iowa , Iowa city , IA , USA
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19
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Reynolds ER. Shortened Lifespan and Other Age-Related Defects in Bang Sensitive Mutants of Drosophila melanogaster. G3 (BETHESDA, MD.) 2018; 8:3953-3960. [PMID: 30355763 PMCID: PMC6288826 DOI: 10.1534/g3.118.200610] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/18/2018] [Indexed: 11/28/2022]
Abstract
Mitochondrial diseases are complex disorders that exhibit their primary effects in energetically active tissues. Damage generated by mitochondria is also thought to be a key component of aging and age-related disease. An important model for mitochondrial dysfunction is the bang sensitive (bs) mutants in Drosophila melanogaster Although these mutants all show a striking seizure phenotype, several bs mutants have gene products that are involved with mitochondrial function, while others affect excitability another way. All of the bs mutants (parabss , eas, jus, ses B, tko are examined here) paralyze and seize upon challenge with a sensory stimulus, most notably mechanical stimulation. These and other excitability mutants have been linked to neurodegeneration with age. In addition to these phenotypes, we have found age-related defects for several of the bs strains. The mutants eas, ses B, and tko display shortened lifespan, an increased mean recovery time from seizure with age, and decreased climbing ability over lifespan as compared to isogenic CS or w1118 lines. Other mutants show a subset of these defects. The age-related phenotypes can be rescued by feeding melatonin, an antioxidant, in all the mutants except ses B The age-related defects do not appear to be correlated with the seizure phenotype. Inducing seizures on a daily basis did not exacerbate the phenotypes and treatment with antiepileptic drugs did not increase lifespan. The results suggest that the excitability phenotypes and the age-related phenotypes may be somewhat independent and that these phenotypes mutants may arise from impacts on different pathways.
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20
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Marcogliese PC, Shashi V, Spillmann RC, Stong N, Rosenfeld JA, Koenig MK, Martínez-Agosto JA, Herzog M, Chen AH, Dickson PI, Lin HJ, Vera MU, Salamon N, Graham JM, Ortiz D, Infante E, Steyaert W, Dermaut B, Poppe B, Chung HL, Zuo Z, Lee PT, Kanca O, Xia F, Yang Y, Smith EC, Jasien J, Kansagra S, Spiridigliozzi G, El-Dairi M, Lark R, Riley K, Koeberl DD, Golden-Grant K, Yamamoto S, Wangler MF, Mirzaa G, Hemelsoet D, Lee B, Nelson SF, Goldstein DB, Bellen HJ, Pena LDM. IRF2BPL Is Associated with Neurological Phenotypes. Am J Hum Genet 2018; 103:245-260. [PMID: 30057031 PMCID: PMC6081494 DOI: 10.1016/j.ajhg.2018.07.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/02/2018] [Indexed: 12/23/2022] Open
Abstract
Interferon regulatory factor 2 binding protein-like (IRF2BPL) encodes a member of the IRF2BP family of transcriptional regulators. Currently the biological function of this gene is obscure, and the gene has not been associated with a Mendelian disease. Here we describe seven individuals who carry damaging heterozygous variants in IRF2BPL and are affected with neurological symptoms. Five individuals who carry IRF2BPL nonsense variants resulting in a premature stop codon display severe neurodevelopmental regression, hypotonia, progressive ataxia, seizures, and a lack of coordination. Two additional individuals, both with missense variants, display global developmental delay and seizures and a relatively milder phenotype than those with nonsense alleles. The IRF2BPL bioinformatics signature based on population genomics is consistent with a gene that is intolerant to variation. We show that the fruit-fly IRF2BPL ortholog, called pits (protein interacting with Ttk69 and Sin3A), is broadly detected, including in the nervous system. Complete loss of pits is lethal early in development, whereas partial knockdown with RNA interference in neurons leads to neurodegeneration, revealing a requirement for this gene in proper neuronal function and maintenance. The identified IRF2BPL nonsense variants behave as severe loss-of-function alleles in this model organism, and ectopic expression of the missense variants leads to a range of phenotypes. Taken together, our results show that IRF2BPL and pits are required in the nervous system in humans and flies, and their loss leads to a range of neurological phenotypes in both species.
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Affiliation(s)
- Paul C Marcogliese
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Vandana Shashi
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Rebecca C Spillmann
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Nicholas Stong
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mary Kay Koenig
- Division of Child & Adolescent Neurology, Department of Pediatrics, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Julián A Martínez-Agosto
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Child and Adolescent Psychiatry, Resnick Neuropsychiatric Hospital, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Matthew Herzog
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Agnes H Chen
- Department of Pediatrics, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA
| | - Patricia I Dickson
- Department of Pediatrics, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA
| | - Henry J Lin
- Department of Pediatrics, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA
| | - Moin U Vera
- Department of Pediatrics, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA
| | - Noriko Salamon
- Department of Radiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - John M Graham
- Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Damara Ortiz
- Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Elena Infante
- Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, University of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Wouter Steyaert
- Department of Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
| | - Bart Dermaut
- Department of Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
| | - Bruce Poppe
- Department of Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
| | - Hyung-Lok Chung
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Fan Xia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yaping Yang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Edward C Smith
- Division of Neurology, Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Joan Jasien
- Division of Neurology, Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Sujay Kansagra
- Division of Neurology, Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Gail Spiridigliozzi
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC 27710, USA
| | - Mays El-Dairi
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Robert Lark
- Department of Orthopedic Surgery, Duke University School of Medicine, Durham, NC 27710, USA
| | - Kacie Riley
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Dwight D Koeberl
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA
| | - Katie Golden-Grant
- Division of Genetic Medicine, Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael F Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Ghayda Mirzaa
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98105, USA; Department of Pediatrics, University of Washington, Seattle, WA 98105, USA
| | - Dimitri Hemelsoet
- Department of Neurology, Ghent University Hospital, 9000 Ghent, Belgium
| | - Brendan Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stanley F Nelson
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY 10032, USA
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Loren D M Pena
- Division of Medical Genetics, Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA.
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21
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Johan Arief MF, Choo BKM, Yap JL, Kumari Y, Shaikh MF. A Systematic Review on Non-mammalian Models in Epilepsy Research. Front Pharmacol 2018; 9:655. [PMID: 29997502 PMCID: PMC6030834 DOI: 10.3389/fphar.2018.00655] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 05/31/2018] [Indexed: 02/03/2023] Open
Abstract
Epilepsy is a common neurological disorder characterized by seizures which result in distinctive neurobiological and behavioral impairments. Not much is known about the causes of epilepsy, making it difficult to devise an effective cure for epilepsy. Moreover, clinical studies involving epileptogenesis and ictogenesis cannot be conducted in humans due to ethical reasons. As a result, animal models play a crucial role in the replication of epileptic seizures. In recent years, non-mammalian models have been given a primary focus in epilepsy research due to their advantages. This systematic review aims to summarize the importance of non-mammalian models in epilepsy research, such as in the screening of anti-convulsive compounds. The reason for this review is to integrate currently available information on the use and importance of non-mammalian models in epilepsy testing to aid in the planning of future studies as well as to provide an overview of the current state of this field. A PRISMA model was utilized and PubMed, Springer, ScienceDirect and SCOPUS were searched for articles published between January 2007 and November 2017. Fifty-one articles were finalized based on the inclusion/exclusion criteria and were discussed in this review. The results of this review demonstrated the current use of non-mammalian models in epilepsy research and reaffirmed their potential to supplement the typical rodent models of epilepsy in future research into both epileptogenesis and the treatment of epilepsy. This review also revealed a preference for zebrafish and fruit flies in lieu of other non-mammalian models, which is a shortcoming that should be corrected in future studies due to the great potential of these underutilized animal models.
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Affiliation(s)
- Muhammad Faiz Johan Arief
- MBBS Young Scholars Program, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia.,Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Brandon Kar Meng Choo
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Jia Ling Yap
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia.,School of Science, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Yatinesh Kumari
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Mohd Farooq Shaikh
- Neuropharmacology Research Laboratory, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
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22
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Unraveling Synaptic GCaMP Signals: Differential Excitability and Clearance Mechanisms Underlying Distinct Ca 2+ Dynamics in Tonic and Phasic Excitatory, and Aminergic Modulatory Motor Terminals in Drosophila. eNeuro 2018; 5:eN-NWR-0362-17. [PMID: 29464198 PMCID: PMC5818553 DOI: 10.1523/eneuro.0362-17.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 01/27/2018] [Accepted: 02/02/2018] [Indexed: 11/21/2022] Open
Abstract
GCaMP is an optogenetic Ca2+ sensor widely used for monitoring neuronal activities but the precise physiological implications of GCaMP signals remain to be further delineated among functionally distinct synapses. The Drosophila neuromuscular junction (NMJ), a powerful genetic system for studying synaptic function and plasticity, consists of tonic and phasic glutamatergic and modulatory aminergic motor terminals of distinct properties. We report a first simultaneous imaging and electric recording study to directly contrast the frequency characteristics of GCaMP signals of the three synapses for physiological implications. Different GCaMP variants were applied in genetic and pharmacological perturbation experiments to examine the Ca2+ influx and clearance processes underlying the GCaMP signal. Distinct mutational and drug effects on GCaMP signals indicate differential roles of Na+ and K+ channels, encoded by genes including paralytic (para), Shaker (Sh), Shab, and ether-a-go-go (eag), in excitability control of different motor terminals. Moreover, the Ca2+ handling properties reflected by the characteristic frequency dependence of the synaptic GCaMP signals were determined to a large extent by differential capacity of mitochondria-powered Ca2+ clearance mechanisms. Simultaneous focal recordings of synaptic activities further revealed that GCaMPs were ineffective in tracking the rapid dynamics of Ca2+ influx that triggers transmitter release, especially during low-frequency activities, but more adequately reflected cytosolic residual Ca2+ accumulation, a major factor governing activity-dependent synaptic plasticity. These results highlight the vast range of GCaMP response patterns in functionally distinct synaptic types and provide relevant information for establishing basic guidelines for the physiological interpretations of presynaptic GCaMP signals from in situ imaging studies.
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23
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Dean D, Weinstein H, Amin S, Karno B, McAvoy E, Hoy R, Recknagel A, Jarvis C, Deitcher D. Extending julius seizure, a bang-sensitive gene, as a model for studying epileptogenesis: Cold shock, and a new insertional mutation. Fly (Austin) 2017; 12:55-61. [PMID: 29125376 DOI: 10.1080/19336934.2017.1402993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
The bang-sensitive (BS) mutants of Drosophila are an important model for studying epilepsy. We recently identified a novel BS locus, julius seizure (jus), encoding a protein containing two transmembrane domains and an extracellular cysteine-rich loop. We also determined that jussda iso7.8, a previously identified BS mutation, is an allele of jus by recombination, deficiency mapping, complementation testing, and genetic rescue. RNAi knockdown revealed that jus expression is important in cholinergic neurons and that the critical stage of jus expression is the mid-pupa. Finally, we found that a functional, GFP-tagged genomic construct of jus is expressed mostly in axons of the neck connectives and of the thoracic abdominal ganglia. In this Extra View article, we show that a MiMiC GFP-tagged Jus is localized to the same nervous system regions as the GFP-tagged genomic construct, but its expression is mostly confined to cell bodies and it causes bang-sensitivity. The MiMiC GFP-tag lies in the extracellular loop while the genomic construct is tagged at the C-terminus. This suggests that the alternate position of the GFP tag may disrupt Jus protein function by altering its subcellular localization and/or stability. We also show that a small subset of jus-expressing neurons are responsible for the BS phenotype. Finally, extending the utility of the BS seizure model, we show that jus mutants exhibit cold-sensitive paralysis and are partially sensitive to strobe-induced seizures.
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Affiliation(s)
- Derek Dean
- a Department of Biology , Williams College , Williamstown , MA USA
| | - Hannah Weinstein
- a Department of Biology , Williams College , Williamstown , MA USA
| | - Seema Amin
- a Department of Biology , Williams College , Williamstown , MA USA
| | - Breelyn Karno
- a Department of Biology , Williams College , Williamstown , MA USA
| | - Emma McAvoy
- a Department of Biology , Williams College , Williamstown , MA USA
| | - Ronald Hoy
- b Department of Neurobiology and Behavior , Cornell University , Ithaca , NY USA
| | - Andrew Recknagel
- b Department of Neurobiology and Behavior , Cornell University , Ithaca , NY USA
| | - Casey Jarvis
- b Department of Neurobiology and Behavior , Cornell University , Ithaca , NY USA
| | - David Deitcher
- b Department of Neurobiology and Behavior , Cornell University , Ithaca , NY USA
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24
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Karan KR, Satishchandra P, Sinha S, Anand A. Rare SLC1A1 variants in hot water epilepsy. Hum Genet 2017; 136:693-703. [DOI: 10.1007/s00439-017-1778-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 03/11/2017] [Indexed: 11/30/2022]
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25
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Seizure Suppression by High Temperature via cAMP Modulation in Drosophila. G3-GENES GENOMES GENETICS 2016; 6:3381-3387. [PMID: 27558668 PMCID: PMC5068957 DOI: 10.1534/g3.116.034629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bang-sensitive (BS) Drosophila mutants display characteristic seizure-like activity (SLA) and paralysis after mechanical shock . After high-frequency electrical stimulation (HFS) of the brain, they generate robust seizures at very low threshold voltage. Here we report an important phenomenon, which effectively suppresses SLA in BS mutants. High temperature causes seizure suppression in all BS mutants (parabss1, eas, sda) examined in this study. This effect is fully reversible and flies show complete recovery from BS paralysis once the temperature effect is nullified. High temperature induces an increase in seizure threshold after a brief pulse of heat shock (HS). By genetic screening, we identified the involvement of cAMP in the suppression of seizures by high temperature. We propose that HS induces adenylyl cyclase which in turn increases cAMP concentration which eventually suppresses seizures in mutant flies. In summary, we describe an unusual phenomenon, where high temperature can suppress SLA in flies by modulating cAMP concentration.
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26
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Lucey BP, Leahy A, Rosas R, Shaw PJ. A new model to study sleep deprivation-induced seizure. Sleep 2015; 38:777-85. [PMID: 25515102 DOI: 10.5665/sleep.4674] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 11/07/2014] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND AND STUDY OBJECTIVES A relationship between sleep and seizures is well-described in both humans and rodent animal models; however, the mechanism underlying this relationship is unknown. Using Drosophila melanogaster mutants with seizure phenotypes, we demonstrate that seizure activity can be modified by sleep deprivation. DESIGN Seizure activity was evaluated in an adult bang-sensitive seizure mutant, stress sensitive B (sesB(9ed4)), and in an adult temperature sensitive seizure mutant seizure (sei(ts1)) under baseline and following 12 h of sleep deprivation. The long-term effect of sleep deprivation on young, immature sesB(9ed4) flies was also assessed. SETTING Laboratory. PARTICIPANTS Drosophila melanogaster. INTERVENTIONS Sleep deprivation. MEASUREMENTS AND RESULTS Sleep deprivation increased seizure susceptibility in adult sesB(9ed4)/+ and sei(ts1) mutant flies. Sleep deprivation also increased seizure susceptibility when sesB was disrupted using RNAi. The effect of sleep deprivation on seizure activity was reduced when sesB(9ed4)/+ flies were given the anti-seizure drug, valproic acid. In contrast to adult flies, sleep deprivation during early fly development resulted in chronic seizure susceptibility when sesB(9ed4)/+ became adults. CONCLUSIONS These findings show that Drosophila is a model organism for investigating the relationship between sleep and seizure activity.
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Affiliation(s)
- Brendan P Lucey
- Department of Neurology, Washington University School of Medicine, Saint Louis, MO
| | - Averi Leahy
- Department of Anatomy and Neurobiology, Washington University School of Medicine, Saint Louis, MO
| | - Regine Rosas
- Department of Anatomy and Neurobiology, Washington University School of Medicine, Saint Louis, MO
| | - Paul J Shaw
- Department of Anatomy and Neurobiology, Washington University School of Medicine, Saint Louis, MO
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27
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Katzenberger RJ, Chtarbanova S, Rimkus SA, Fischer JA, Kaur G, Seppala JM, Swanson LC, Zajac JE, Ganetzky B, Wassarman DA. Death following traumatic brain injury in Drosophila is associated with intestinal barrier dysfunction. eLife 2015; 4. [PMID: 25742603 PMCID: PMC4377547 DOI: 10.7554/elife.04790] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 03/05/2015] [Indexed: 12/15/2022] Open
Abstract
Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Unfavorable TBI outcomes result from primary mechanical injuries to the brain and ensuing secondary non-mechanical injuries that are not limited to the brain. Our genome-wide association study of Drosophila melanogaster revealed that the probability of death following TBI is associated with single nucleotide polymorphisms in genes involved in tissue barrier function and glucose homeostasis. We found that TBI causes intestinal and blood–brain barrier dysfunction and that intestinal barrier dysfunction is highly correlated with the probability of death. Furthermore, we found that ingestion of glucose after a primary injury increases the probability of death through a secondary injury mechanism that exacerbates intestinal barrier dysfunction. Our results indicate that natural variation in the probability of death following TBI is due in part to genetic differences that affect intestinal barrier dysfunction. DOI:http://dx.doi.org/10.7554/eLife.04790.001 Traumatic brain injury (TBI) caused by a violent blow to the head or body and the resultant collision of the brain against the skull is a major cause of disability and death in humans. Primary injury to the brain triggers secondary injuries that further damage the brain and other organs, generating many of the detrimental consequences of TBI. However, despite decades of study, the exact nature of these secondary injuries and their origin are poorly understood. A better understanding of secondary injuries should help to develop novel therapies to improve TBI outcomes in affected individuals. To obtain this information, in 2013 researchers devised a method to inflict TBI in the common fruit fly, Drosophila melanogaster, an organism that is readily amenable to detailed genetic and molecular studies. This investigation demonstrated that flies subjected to TBI display many of the same symptoms observed in humans after a brain injury, including temporary loss of mobility and damage to the brain that becomes worse over time. In addition, many of the flies die within 24 hr after brain injury. Now Katzenberger et al. use this experimental system to investigate the secondary injuries responsible for these deaths. First, genetic variants were identified that confer increased or decreased susceptibility to death after brain injury. Several of the identified genes affect the structural integrity of the intestinal barrier that isolates the contents of the gut—including nutrients and bacteria—from the circulatory system. Katzenberger et al. subsequently found that the breakdown of this barrier after brain injury permits bacteria and glucose to leak out of the intestine. Treating flies with antibiotics did not increase survival, whereas reducing glucose levels in the circulatory system after brain injury did. Thus, Katzenberger et al. conclude that high levels of glucose in the circulatory system, a condition known as hyperglycemia, is a key culprit in death following TBI. Notably, these results parallel findings in humans, where hyperglycemia is highly predictive of death following TBI. Similarly, individuals with diabetes have a significantly increased risk of death after TBI. These results suggest that the secondary injuries leading to death are the same in flies and humans and that further studies in flies are likely to provide additional new information that will help us understand the complex consequences of TBI. Important challenges remain, including understanding precisely how the brain and intestine communicate, how injury to the brain leads to disruption of the intestinal barrier, and why elevated glucose levels increase mortality after brain injury. Answers to these questions could help pave the way to new therapies for TBI. DOI:http://dx.doi.org/10.7554/eLife.04790.002
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Affiliation(s)
- Rebeccah J Katzenberger
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States
| | | | - Stacey A Rimkus
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States
| | - Julie A Fischer
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States
| | - Gulpreet Kaur
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States
| | - Jocelyn M Seppala
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States
| | - Laura C Swanson
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States
| | - Jocelyn E Zajac
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States
| | - Barry Ganetzky
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, United States
| | - David A Wassarman
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, United States
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28
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Iyengar A, Wu CF. Flight and seizure motor patterns in Drosophila mutants: simultaneous acoustic and electrophysiological recordings of wing beats and flight muscle activity. J Neurogenet 2014; 28:316-28. [PMID: 25159538 PMCID: PMC5555410 DOI: 10.3109/01677063.2014.957827] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Abstract Tethered flies allow studies of biomechanics and electrophysiology of flight control. We performed microelectrode recordings of spikes in an indirect flight muscle (the dorsal longitudinal muscle, DLMa) coupled with acoustic analysis of wing beat frequency (WBF) via microphone signals. Simultaneous electrophysiological recording of direct and indirect flight muscles has been technically challenging; however, the WBF is thought to reflect in a one-to-one relationship with spiking activity in a subset of direct flight muscles, including muscle m1b. Therefore, our approach enables systematic mutational analysis for changes in temporal features of electrical activity of motor neurons innervating subsets of direct and indirect flight muscles. Here, we report the consequences of specific ion channel disruptions on the spiking activity of myogenic DLMs (firing at ∼5 Hz) and the corresponding WBF (∼200 Hz). We examined mutants of the genes enconding: 1) voltage-gated Ca(2+) channels (cacophony, cac), 2) Ca(2+)-activated K(+) channels (slowpoke, slo), and 3) voltage-gated K(+) channels (Shaker, Sh) and their auxiliary subunits (Hyperkinetic, Hk and quiver, qvr). We found flight initiation in response to an air puff was severely disrupted in both cac and slo mutants. However, once initiated, slo flight was largely unaltered, whereas cac displayed disrupted DLM firing rates and WBF. Sh, Hk, and qvr mutants were able to maintain normal DLM firing rates, despite increased WBF. Notably, defects in the auxiliary subunits encoded by Hk and qvr could lead to distinct consequences, that is, disrupted DLM firing rhythmicity, not observed in Sh. Our mutant analysis of direct and indirect flight muscle activities indicates that the two motor activity patterns may be independently modified by specific ion channel mutations, and that this approach can be extended to other dipteran species and additional motor programs, such as electroconvulsive stimulation-induced seizures.
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Affiliation(s)
- Atulya Iyengar
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242, USA
| | - Chun-Fang Wu
- Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa City, IA 52242, USA
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA
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