title: Simultaneous impairment of neuronal and metabolic function of mutated gephyrin in a patient with epileptic encephalopathy.
abstract: Synaptic inhibition is essential for shaping the dynamics of neuronal networks, and aberrant inhibition plays an important role in neurological disorders. Gephyrin is a central player at inhibitory postsynapses, directly binds and organizes GABAA and glycine receptors (GABAARs and GlyRs), and is thereby indispensable for normal inhibitory neurotransmission. Additionally, gephyrin catalyzes the synthesis of the molybdenum cofactor (MoCo) in peripheral tissue. We identified a de novo missense mutation (G375D) in the gephyrin gene (GPHN) in a patient with epileptic encephalopathy resembling Dravet syndrome. Although stably expressed and correctly folded, gephyrin-G375D was non-synaptically localized in neurons and acted dominant-negatively on the clustering of wild-type gephyrin leading to a marked decrease in GABAAR surface expression and GABAergic signaling. We identified a decreased binding affinity between gephyrin-G375D and the receptors, suggesting that Gly375 is essential for gephyrin-receptor complex formation. Surprisingly, gephyrin-G375D was also unable to synthesize MoCo and activate MoCo-dependent enzymes. Thus, we describe a missense mutation that affects both functions of gephyrin and suggest that the identified defect at GABAergic synapses is the mechanism underlying the patient's severe phenotype.
authors.affiliation: Department of Chemistry, Institute of Biochemistry University of Cologne, Cologne, Germany b.dejanovic@uni-koeln.de sarahweck@hotmail.com gschwarz@uni-koeln.de.
authors.forename: Borislav
authors.initials: B
authors.lastname: Dejanovic
authors.affiliation: Neurogenetics Group, Department of Molecular Genetics, VIB, Antwerp, Belgium Laboratory of Neurogenetics, Institute Born-Bunge University of Antwerp, Antwerp, Belgium.
authors.forename: Tania
authors.initials: T
authors.lastname: Djémié
authors.affiliation: Department of Chemistry, Institute of Biochemistry University of Cologne, Cologne, Germany.
authors.forename: Nora
authors.initials: N
authors.lastname: Grünewald
authors.affiliation: Neurogenetics Group, Department of Molecular Genetics, VIB, Antwerp, Belgium Laboratory of Neurogenetics, Institute Born-Bunge University of Antwerp, Antwerp, Belgium GENOMED, Center for Medical Genetics, University of Antwerp, Antwerp, Belgium.
authors.forename: Arvid
authors.initials: A
authors.lastname: Suls
authors.affiliation: Department of Chemistry, Institute of Biochemistry University of Cologne, Cologne, Germany.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Kress
authors.affiliation: Division Cell Physiology, Zoological Institute Technische Universität Braunschweig, Braunschweig, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Hetsch
authors.affiliation: Pediatric Neurology Clinic, Al Obregia Hospital, Bucharest, Romania Department of Neurology, Pediatric Neurology, Psychiatry, Child and Adolescent Psychiatry, and Neurosurgery, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.
authors.forename: Dana
authors.initials: D
authors.lastname: Craiu
authors.affiliation: Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Zemel
authors.affiliation: Wellcome Trust Sanger Institute Wellcome Trust Genome Campus, Hinxton, UK Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) University of Cologne, Cologne, Germany Psychiatric & Neurodevelopmental Genetics Unit, Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Padhraig
authors.initials: P
authors.lastname: Gormley
authors.affiliation: Cologne Center for Genomics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) University of Cologne, Cologne, Germany Department of Neuropediatrics, University Medical Faculty Giessen and Marburg, Giessen, Germany.
authors.forename: Dennis
authors.initials: D
authors.lastname: Lal
authors.affiliation: Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA, USA.
authors.forename: Candace T
authors.initials: CT
authors.lastname: Myers
authors.affiliation: Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA, USA.
authors.forename: Heather C
authors.initials: HC
authors.lastname: Mefford
authors.affiliation: Wellcome Trust Sanger Institute Wellcome Trust Genome Campus, Hinxton, UK Psychiatric & Neurodevelopmental Genetics Unit, Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland Program in Medical and Population Genetics, The Broad Institute of MIT and Harvard, Cambridge, MA, USA The Stanley Center for Psychiatric Research, The Broad Institute of MIT and Harvard, Cambridge, MA, USA Analytic and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Aarno
authors.initials: A
authors.lastname: Palotie
authors.affiliation: Department of Neuropediatrics, University Medical Center Schleswig-Holstein Christian Albrechts University, Kiel, Germany Division of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
authors.forename: Ingo
authors.initials: I
authors.lastname: Helbig
authors.affiliation: Division Cell Physiology, Zoological Institute Technische Universität Braunschweig, Braunschweig, Germany.
authors.forename: Jochen C
authors.initials: JC
authors.lastname: Meier
authors.affiliation: Neurogenetics Group, Department of Molecular Genetics, VIB, Antwerp, Belgium Laboratory of Neurogenetics, Institute Born-Bunge University of Antwerp, Antwerp, Belgium Division of Neurology, Antwerp University Hospital, Antwerp, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: De Jonghe
authors.affiliation: Neurogenetics Group, Department of Molecular Genetics, VIB, Antwerp, Belgium Laboratory of Neurogenetics, Institute Born-Bunge University of Antwerp, Antwerp, Belgium Inserm U 1127 CNRS UMR 7225 Sorbonne Universités UPMC Univ Paris 06 UMR S 1127 Institut du Cerveau et de la Moelle épinière, ICM, Paris, France Centre de reference épilepsies rares, Epilepsy unit, AP-HP Groupe hospitalier Pitié-Salpêtrière, F-75013, Paris, France b.dejanovic@uni-koeln.de sarahweck@hotmail.com gschwarz@uni-koeln.de.
authors.forename: Sarah
authors.initials: S
authors.lastname: Weckhuysen
authors.affiliation: Department of Chemistry, Institute of Biochemistry University of Cologne, Cologne, Germany Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) University of Cologne, Cologne, Germany b.dejanovic@uni-koeln.de sarahweck@hotmail.com gschwarz@uni-koeln.de.
authors.forename: Guenter
authors.initials: G
authors.lastname: Schwarz
mesh_terms: D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D003067:Coenzymes / Q000378:metabolism; D004827:Epilepsy / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D008667:Metalloproteins / Q000378:metabolism; D000090006:Molybdenum Cofactors; D020125:Mutation, Missense; D011621:Pteridines / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism; D013569:Synapses / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D003067:Coenzymes; D008565:Membrane Proteins; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D011621:Pteridines; D011963:Receptors, GABA-A; C073441:gephyrin; C022261:molybdopterin
keywords: Dravet syndrome; GABAA receptors; epileptic encephalopathy; gephyrin; molybdenum cofactor