title: Extracellular signal-regulated kinase and glycogen synthase kinase 3β regulate gephyrin postsynaptic aggregation and GABAergic synaptic function in a calpain-dependent mechanism.
abstract: Molecular mechanisms of plasticity at GABAergic synapses are currently poorly understood. To identify signaling cascades that converge onto GABAergic postsynaptic density proteins, we performed MS analysis using gephyrin isolated from rat brain and identified multiple novel phosphorylation and acetylation residues on gephyrin. Here, we report the characterization of one of these phosphoresidues, Ser-268, which when dephosphorylated leads to the formation of larger postsynaptic scaffolds. Using a combination of mutagenesis, pharmacological treatment, and biochemical assays, we identify ERK as the kinase phosphorylating Ser-268 and describe a functional interaction between residues Ser-268 and Ser-270. We further demonstrate that alterations in gephyrin clustering via ERK modulation are reflected by amplitude and frequency changes in miniature GABAergic postsynaptic currents. We unravel novel mechanisms for activity- and ERK-dependent calpain action on gephyrin, which are likely relevant in the context of cellular signaling affecting GABAergic transmission and homeostatic synaptic plasticity in pathology.
authors: Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, Zurich, 8057 Switzerland. Electronic address: tyagarajan@pharma.uzh.ch.
authors: Shiva K
authors: SK
authors: Tyagarajan
authors: Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, Zurich, 8057 Switzerland.
authors: Himanish
authors: H
authors: Ghosh
authors: Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland.
authors: Gonzalo E
authors: GE
authors: Yévenes
authors: Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520 Turku, Finland.
authors: Susumu Y
authors: SY
authors: Imanishi
authors: Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, Zurich, 8057 Switzerland; Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, 8093 Switzerland.
authors: Hanns Ulrich
authors: HU
authors: Zeilhofer
authors: Functional Genomics Center Zurich, 8057 Zurich, Switzerland.
authors: Bertran
authors: B
authors: Gerrits
authors: Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, Zurich, 8057 Switzerland.
authors: Jean-Marc
authors: JM
authors: Fritschy
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D004594:Electrophysiology / Q000379:methods; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D057809:HEK293 Cells; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D008565:Membrane Proteins / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D009474:Neurons / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D051381:Rats; D013569:Synapses / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; C073441:gephyrin; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D048052:Mitogen-Activated Protein Kinase 3; D038362:Glycogen Synthase Kinase 3; D002154:Calpain