title: Seizure control through genetic and pharmacological manipulation of Pumilio in Drosophila: a key component of neuronal homeostasis.
abstract: Epilepsy is a significant disorder for which approximately one-third of patients do not respond to drug treatments. Next-generation drugs, which interact with novel targets, are required to provide a better clinical outcome for these individuals. To identify potential novel targets for antiepileptic drug (AED) design, we used RNA sequencing to identify changes in gene transcription in two seizure models of the fruit fly Drosophila melanogaster The first model compared gene transcription between wild type (WT) and bangsenseless1(parabss), a gain-of-function mutant in the sole fly voltage-gated sodium channel (paralytic). The second model compared WT with WT fed the proconvulsant picrotoxin (PTX). We identified 743 genes (FDR≤1%) with significant altered expression levels that are common to both seizure models. Of these, 339 are consistently upregulated and 397 downregulated. We identify pumilio (pum) to be downregulated in both seizure models. Pum is a known homeostatic regulator of action potential firing in both flies and mammals, achieving control of neuronal firing through binding to, and regulating translation of, the mRNA transcripts of voltage-gated sodium channels (Nav). We show that maintaining expression of pum in the CNS of parabssflies is potently anticonvulsive, whereas its reduction through RNAi-mediated knockdown is proconvulsive. Using a cell-based luciferase reporter screen, we screened a repurposed chemical library and identified 12 compounds sufficient to increase activity of pum Of these compounds, we focus on avobenzone, which significantly rescues seizure behaviour in parabssflies. The mode of action of avobenzone includes potentiation of pum expression and mirrors the ability of this homeostatic regulator to reduce the persistent voltage-gated Na+current (INaP) in an identified neuron. This study reports a novel approach to suppress seizure and highlights the mechanisms of neuronal homeostasis as potential targets for next-generation AEDs.
authors.affiliation: Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK.
authors.forename: Wei-Hsiang
authors.initials: WH
authors.lastname: Lin
authors.affiliation: Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK.
authors.forename: Carlo N G
authors.initials: CN
authors.lastname: Giachello
authors.affiliation: Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK Richard.Baines@manchester.ac.uk.
authors.forename: Richard A
authors.identifier: 0000-0001-8571-4376
authors.initials: RA
authors.lastname: Baines
mesh_terms: D000818:Animals; D000927:Anticonvulsants; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000187:drug effects / Q000235:genetics*; D004827:Epilepsy / Q000188:drug therapy / Q000235:genetics / Q000473:pathology; D020022:Genetic Predisposition to Disease; D006706:Homeostasis / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D011427:Propiophenones / Q000494:pharmacology / Q000627:therapeutic use*; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D012640:Seizures / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D017423:Sequence Analysis, RNA; D014158:Transcription, Genetic / Q000187:drug effects; D019076:Transgenes; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D000927:Anticonvulsants; D029721:Drosophila Proteins; D011427:Propiophenones; D016601:RNA-Binding Proteins; C074333:pum protein, Drosophila; C049935:avobenzone
keywords: Anticonvulsant; Drosophila; Epilepsy; Pumilio; Sodium current; Translational repression