Endosomal phosphatidylinositol 3-phosphate promotes gephyrin clustering and GABAergic neurotransmission at inhibitory postsynapses

Theofilos Papadopoulos, Hong Jun Rhee, Devaraj Subramanian, Foteini Paraskevopoulou, Rainer Mueller, Carsten Schultz, Nils Brose, Jeong Seop Rhee, Heinrich Betz

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13 Scopus citations

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 Cbbinds 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, timelapse 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 GABAA receptors 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 Cbmediated recruitment of gephyrin and GABAA receptors to developing inhibitory postsynapses and thus the formation of postsynaptic membrane specializations.

Original languageEnglish (US)
Pages (from-to)1160-1177
Number of pages18
JournalJournal of Biological Chemistry
Volume292
Issue number4
DOIs
StatePublished - Jan 27 2017

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Papadopoulos, T., Rhee, H. J., Subramanian, D., Paraskevopoulou, F., Mueller, R., Schultz, C., Brose, N., Rhee, J. S., & Betz, H. (2017). Endosomal phosphatidylinositol 3-phosphate promotes gephyrin clustering and GABAergic neurotransmission at inhibitory postsynapses. Journal of Biological Chemistry, 292(4), 1160-1177. https://doi.org/10.1074/jbc.M116.771592