Association of gephyrin with synaptic and extrasynaptic GABAA receptors varies during development in cultured hippocampal neurons

Mol Cell Neurosci. 2003 Jun;23(2):264-78. doi: 10.1016/s1044-7431(03)00069-1.

Abstract

Several studies have reported extrasynaptic clusters of GABAA receptors in hippocampal neurons. Yet their functional relevance as well as their evolution in relation with gephyrin during synaptogenesis remain unknown. We have analyzed the expression pattern of the main proteins of the GABAergic synapses during synaptogenesis in cultured hippocampal neurons. We found that GABAergic terminals, characterized by VIAAT and GAD-65 expression, differentiated 3 to 7 days after the glutamatergic endings. At the postsynaptic side, the GABAAR- beta3 subunit was first diffuse and then clustered when GABAergic terminals differentiated and gephyrin formed large clusters. Colocalization of these proteins was high and increased with development. At later stages, GABAAR beta3 clusters colocalized with gephyrin at synaptic but also at extrasynaptic sites. GABAAR gamma2 subunits were directly expressed as clusters which were first extrasynaptic and not associated with gephyrin. Subsequently, the GABAAR gamma2 subunits associated with gephyrin at synaptic and/or extrasynaptic sites. Our data indicate that formation of GABAAR gamma2 subunit clusters is gephyrin independent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Transport Systems*
  • Animals
  • Carrier Proteins / metabolism*
  • Cell Differentiation / physiology
  • Cells, Cultured
  • Fetus
  • Glutamate Decarboxylase / metabolism
  • Glutamic Acid / metabolism
  • Hippocampus / cytology
  • Hippocampus / embryology*
  • Hippocampus / metabolism
  • Immunohistochemistry
  • Isoenzymes / metabolism
  • Membrane Proteins / metabolism*
  • Neural Inhibition / physiology
  • Presynaptic Terminals / metabolism*
  • Presynaptic Terminals / ultrastructure
  • Protein Subunits / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, GABA-A / metabolism*
  • Synaptic Membranes / metabolism*
  • Synaptic Transmission / physiology
  • Vesicular Inhibitory Amino Acid Transport Proteins
  • Vesicular Transport Proteins*
  • gamma-Aminobutyric Acid / metabolism

Substances

  • Amino Acid Transport Systems
  • Carrier Proteins
  • Isoenzymes
  • Membrane Proteins
  • Protein Subunits
  • Receptors, GABA-A
  • Vesicular Inhibitory Amino Acid Transport Proteins
  • Vesicular Transport Proteins
  • Viaat protein, rat
  • gephyrin
  • Glutamic Acid
  • gamma-Aminobutyric Acid
  • Glutamate Decarboxylase
  • glutamate decarboxylase 2