title: Endosomal Phosphatidylinositol 3-Phosphate Promotes Gephyrin Clustering and GABAergic Neurotransmission at Inhibitory Postsynapses.
abstract: The formation of neuronal synapses and the dynamic regulation of their efficacy depend on the proper assembly of the postsynaptic neurotransmitter receptor apparatus. Receptor recruitment to inhibitory GABAergic postsynapses requires the scaffold protein gephyrin and the guanine nucleotide exchange factor collybistin (Cb). In vitro, the pleckstrin homology domain of Cb binds phosphoinositides, specifically phosphatidylinositol 3-phosphate (PI3P). However, whether PI3P is required for inhibitory postsynapse formation is currently unknown. Here, we investigated the role of PI3P at developing GABAergic postsynapses by using a membrane-permeant PI3P derivative, time-lapse confocal imaging, electrophysiology, as well as knockdown and overexpression of PI3P-metabolizing enzymes. Our results provide the first in cellula evidence that PI3P located at early/sorting endosomes regulates the postsynaptic clustering of gephyrin and GABAAreceptors and the strength of inhibitory, but not excitatory, postsynapses in cultured hippocampal neurons. In human embryonic kidney 293 cells, stimulation of gephyrin cluster formation by PI3P depends on Cb. We therefore conclude that the endosomal pool of PI3P, generated by the class III phosphatidylinositol 3-kinase, is important for the Cb-mediated recruitment of gephyrin and GABAAreceptors to developing inhibitory postsynapses and thus the formation of postsynaptic membrane specializations.
authors.affiliation: From the Department of Molecular Biology, Center of Biochemistry and Molecular Cell Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany, theofilos.papadopoulos@med.uni-goettingen.de.
authors.forename: Theofilos
authors.identifier: 0000-0002-0684-2407
authors.initials: T
authors.lastname: Papadopoulos
authors.affiliation: the Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany.
authors.forename: Hong Jun
authors.initials: HJ
authors.lastname: Rhee
authors.affiliation: the European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Devaraj
authors.initials: D
authors.lastname: Subramanian
authors.affiliation: From the Department of Molecular Biology, Center of Biochemistry and Molecular Cell Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany.
authors.forename: Foteini
authors.initials: F
authors.lastname: Paraskevopoulou
authors.affiliation: the European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Mueller
authors.affiliation: the European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.|the Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon 97239-3098.
authors.forename: Carsten
authors.initials: C
authors.lastname: Schultz
authors.affiliation: the Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Brose
authors.affiliation: the Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany.
authors.forename: Jeong-Seop
authors.initials: JS
authors.lastname: Rhee
authors.affiliation: the Department of Neurochemistry, Max Planck Institute for Brain Research, Deutschordenstrasse 46, 60528 Frankfurt am Main, Germany, and.|the Max Planck Institute of Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany.
authors.forename: Heinrich
authors.initials: H
authors.lastname: Betz
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism*; D059330:GABAergic Neurons / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors / Q000378:metabolism; D013570:Synaptic Membranes / Q000378:metabolism*; D055366:Synaptic Potentials / Q000502:physiology*
chemical_list: C577404:Arhgef9 protein, rat; D002352:Carrier Proteins; D008565:Membrane Proteins; D018129:Phosphatidylinositol Phosphates; D011963:Receptors, GABA-A; D064067:Rho Guanine Nucleotide Exchange Factors; C073441:gephyrin; C055525:phosphatidylinositol 3-phosphate; D019869:Phosphatidylinositol 3-Kinases
keywords: GABA receptor; inositol phospholipid; phosphatidylinositol phosphatase; synapse; vesicles