title: Seizures are regulated by ubiquitin-specific peptidase 9 X-linked (USP9X), a de-ubiquitinase.
abstract: Epilepsy is a common disabling disease with complex, multifactorial genetic and environmental etiology. The small fraction of epilepsies subject to Mendelian inheritance offers key insight into epilepsy disease mechanisms; and pathologies brought on by mutations in a single gene can point the way to generalizable therapeutic strategies. Mutations in the PRICKLE genes can cause seizures in humans, zebrafish, mice, and flies, suggesting the seizure-suppression pathway is evolutionarily conserved. This pathway has never been targeted for novel anti-seizure treatments. Here, the mammalian PRICKLE-interactome was defined, identifying prickle-interacting proteins that localize to synapses and a novel interacting partner, USP9X, a substrate-specific de-ubiquitinase. PRICKLE and USP9X interact through their carboxy-termini; and USP9X de-ubiquitinates PRICKLE, protecting it from proteasomal degradation. In forebrain neurons of mice, USP9X deficiency reduced levels of Prickle2 protein. Genetic analysis suggests the same pathway regulates Prickle-mediated seizures. The seizure phenotype was suppressed in prickle mutant flies by the small-molecule USP9X inhibitor, Degrasyn/WP1130, or by reducing the dose of fat facets a USP9X orthologue. USP9X mutations were identified by resequencing a cohort of patients with epileptic encephalopathy, one patient harbored a de novo missense mutation and another a novel coding mutation. Both USP9X variants were outside the PRICKLE-interacting domain. These findings demonstrate that USP9X inhibition can suppress prickle-mediated seizure activity, and that USP9X variants may predispose to seizures. These studies point to a new target for anti-seizure therapy and illustrate the translational power of studying diseases in species across the evolutionary spectrum.
authors.affiliation: Department of Pediatrics, The University of Iowa, Iowa City, Iowa, United States of America; Interdisciplinary Program in Genetics, The University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Lily
authors.initials: L
authors.lastname: Paemka
authors.affiliation: Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa, United States of America; Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America; Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Vinit B
authors.initials: VB
authors.lastname: Mahajan
authors.affiliation: Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America; King Abdullah International Medical Research Center, King Abdulaziz Medical City, Riyadh, KSA.
authors.forename: Salleh N
authors.initials: SN
authors.lastname: Ehaideb
authors.affiliation: Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa, United States of America; Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Skeie
authors.affiliation: Eskitis Institute for Drug Discovery, Griffith University, Brisbane, Australia.
authors.forename: Men Chee
authors.initials: MC
authors.lastname: Tan
authors.affiliation: Department of Pediatrics, The University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Shu
authors.initials: S
authors.lastname: Wu
authors.affiliation: Department of Pediatrics, The University of Iowa, Iowa City, Iowa, United States of America; Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Allison J
authors.initials: AJ
authors.lastname: Cox
authors.affiliation: Interdisciplinary Graduate Program of Neuroscience, Department of Veterans Affairs Medical Center, Iowa City, Iowa, United States of America.
authors.forename: Levi P
authors.initials: LP
authors.lastname: Sowers
authors.affiliation: School of Paediatrics and Reproductive Health, Robinson Institute, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Jozef
authors.initials: J
authors.lastname: Gecz
authors.affiliation: School of Paediatrics and Reproductive Health, Robinson Institute, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Lachlan
authors.initials: L
authors.lastname: Jolly
authors.affiliation: Department of Pediatrics, The University of Iowa, Iowa City, Iowa, United States of America; Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Polly J
authors.initials: PJ
authors.lastname: Ferguson
authors.affiliation: Department of Pediatrics, The University of Iowa, Iowa City, Iowa, United States of America; Interdisciplinary Program in Genetics, The University of Iowa, Iowa City, Iowa, United States of America; Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Darbro
authors.affiliation: Epilepsy Research Centre, Department of Medicine, University of Melbourne, The Florey, Austin Health, Heidelberg, Melbourne, Australia.
authors.forename: Amy
authors.initials: A
authors.lastname: Schneider
authors.affiliation: Epilepsy Research Centre, Department of Medicine, University of Melbourne, The Florey, Austin Health, Heidelberg, Melbourne, Australia.
authors.forename: Ingrid E
authors.initials: IE
authors.lastname: Scheffer
authors.affiliation: Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, United States of America.
authors.forename: Gemma L
authors.initials: GL
authors.lastname: Carvill
authors.affiliation: Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, Washington, United States of America.
authors.forename: Heather C
authors.initials: HC
authors.lastname: Mefford
authors.affiliation: Department of Pediatrics, The University of Iowa, Iowa City, Iowa, United States of America; Qatar Biomedical Research Institute Medical Genetics Center, Doha, Qatar.
authors.forename: Hatem
authors.initials: H
authors.lastname: El-Shanti
authors.affiliation: Eskitis Institute for Drug Discovery, Griffith University, Brisbane, Australia.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Wood
authors.affiliation: Department of Pediatrics, The University of Iowa, Iowa City, Iowa, United States of America; Interdisciplinary Program in Genetics, The University of Iowa, Iowa City, Iowa, United States of America; Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America; Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America; Interdisciplinary Graduate Program in Molecular and Cellular Biology, The University of Iowa, Iowa City, Iowa, United States of America; Interdisciplinary Graduate Program in Neuroscience, The University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: J Robert
authors.initials: JR
authors.lastname: Manak
authors.affiliation: Department of Pediatrics, The University of Iowa, Iowa City, Iowa, United States of America; Interdisciplinary Program in Genetics, The University of Iowa, Iowa City, Iowa, United States of America; Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa, United States of America; Interdisciplinary Graduate Program in Molecular and Cellular Biology, The University of Iowa, Iowa City, Iowa, United States of America; Interdisciplinary Graduate Program in Neuroscience, The University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Bassuk
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster; D006801:Humans; D013058:Mass Spectrometry; D051379:Mice; D012640:Seizures / Q000188:drug therapy / Q000378:metabolism*; D043222:Ubiquitin Thiolesterase / Q000235:genetics / Q000378:metabolism*
chemical_list: C506234:USP9X protein, human; D043222:Ubiquitin Thiolesterase