title: Postsynaptic gephyrin clustering controls the development of adult-born granule cells in the olfactory bulb.
abstract: In adult rodent olfactory bulb, GABAergic signaling regulates migration, differentiation, and synaptic integration of newborn granule cells (GCs), migrating from the subventricular zone. Here we show that these effects depend on the formation of a postsynaptic scaffold organized by gephyrin-the main scaffolding protein of GABAergic synapses, which anchors receptors and signaling molecules to the postsynaptic density-and are regulated by the phosphorylation status of gephyrin. Using lentiviral vectors to selectively transfect adult-born GCs, we observed that overexpression of the phospho-deficient gephyrin mutant eGFP-gephyrin(S270A), which facilitates the formation of supernumerary GABAergic synapses in vitro, favors dendritic branching and the formation of transient GABAergic synapses on spines, identified by the presence of α2-GABAA Rs. In contrast, overexpression of the dominant-negative eGFP-gephyrin(L2B) (a chimera that is enzymatically active but clustering defective), curtailed dendritic growth, spine formation, and long-term survival of GCs, pointing to the essential role of gephyrin cluster formation for its function. We could exclude any gephyrin overexpression artifacts, as GCs infected with eGFP-gephyrin were comparable to those infected with eGFP alone. The opposite effects induced by the two gephyrin mutant constructs indicate that the gephyrin scaffold at GABAergic synapses orchestrates signaling cascades acting on the cytoskeleton to regulate neuronal growth and synapse formation. Specifically, gephyrin phosphorylation emerges as a novel mechanism regulating morphological differentiation and long-term survival of adult-born olfactory bulb neurons.
authors.affiliation: University of Zurich, Institute of Pharmacology and Toxicology, 8057, Zurich, Switzerland.|Neuroscience Center Zurich, ETH and University of Zurich, Switzerland.
authors.forename: Francine
authors.initials: F
authors.lastname: Deprez
authors.affiliation: Circuit Dynamics and Connectivity Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Marta
authors.initials: M
authors.lastname: Pallotto
authors.affiliation: University of Zurich, Institute of Pharmacology and Toxicology, 8057, Zurich, Switzerland.
authors.forename: Fabia
authors.initials: F
authors.lastname: Vogt
authors.affiliation: University of Zurich, Institute of Pharmacology and Toxicology, 8057, Zurich, Switzerland.
authors.forename: Marta
authors.initials: M
authors.lastname: Grabiec
authors.affiliation: Department of Neurosciences Fondamentales CMU, University of Geneva, 1211, Geneva, Switzerland.
authors.forename: Mari A
authors.initials: MA
authors.lastname: Virtanen
authors.affiliation: University of Zurich, Institute of Pharmacology and Toxicology, 8057, Zurich, Switzerland.|Neuroscience Center Zurich, ETH and University of Zurich, Switzerland.
authors.forename: Shiva K
authors.initials: SK
authors.lastname: Tyagarajan
authors.affiliation: University of Turin, Department of Neuroscience Rita Levi Montalcini, Turin, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Panzanelli
authors.affiliation: University of Zurich, Institute of Pharmacology and Toxicology, 8057, Zurich, Switzerland.|Neuroscience Center Zurich, ETH and University of Zurich, Switzerland.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Fritschy
mesh_terms: D000367:Age Factors; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D002465:Cell Movement / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D009154:Mutation / Q000235:genetics; D055495:Neurogenesis / Q000502:physiology*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism*; D009830:Olfactory Bulb / Q000166:cytology*; D057907:Post-Synaptic Density / Q000378:metabolism* / Q000648:ultrastructure; D011963:Receptors, GABA-A / Q000378:metabolism; D014161:Transduction, Genetic; D050598:Vesicular Glutamate Transport Protein 1 / Q000378:metabolism; D050495:Vesicular Inhibitory Amino Acid Transport Proteins / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D011963:Receptors, GABA-A; C493465:Slc17a7 protein, mouse; D050598:Vesicular Glutamate Transport Protein 1; D050495:Vesicular Inhibitory Amino Acid Transport Proteins; C492244:Viaat protein, mouse; C485184:enhanced green fluorescent protein; C073441:gephyrin; D049452:Green Fluorescent Proteins
keywords: GABA; RRID:AB_10000240; RRID:AB_1501344; RRID:AB_1586992; RRID:AB_2315546; RRID:AB_887717; RRID:AB_887725; RRID:AB_887869; adult neurogenesis; dendrites; lentiviruses; phosphorylation; postsynaptic density; spines