Tyrosine kinases enhance the function of glycine receptors in rat hippocampal neurons and human alpha(1)beta glycine receptors

J Physiol. 2002 Mar 1;539(Pt 2):495-502. doi: 10.1113/jphysiol.2001.013508.

Abstract

Glycine receptors (GlyRs) are transmitter-gated channels that mediate fast inhibitory neurotransmission in the spinal cord and brain. The GlyR beta subunit contains a putative tyrosine phosphorylation site whose functional role has not been determined. To examine if protein tyrosine kinases (PTKs) regulate the function of GlyRs, we analysed whole-cell currents activated by applications of glycine to CA1 hippocampal neurons and spinal neurons. The role of a putative site for tyrosine phosphorylation at position 413 of the beta subunit was examined using site-directed mutagenesis and expression of recombinant (alpha(1)beta(Y413F)) receptors in human embryonic kidney (HEK 293) cells. Lavendustin A, an inhibitor of PTKs, depressed glycine-evoked currents (I(Gly)) in CA1 neurons and spinal neurons by 31 % and 40 %, respectively. In contrast, the intracellular application of the exogenous tyrosine kinase, cSrc, enhanced I(Gly) in CA1 neurons by 56 %. cSrc also accelerated GlyR desensitization and increased the potency of glycine 2-fold (control EC(50) = 143 microM; cSrc EC(50) = 74 microM). Exogenous cSrc, applied intracellularly, upregulated heteromeric alpha(1)beta receptors but not homomeric alpha(1) receptors. Substitution mutation of the tyrosine to phenylalanine at position beta-413 prevented this enhancement. Furthermore, a selective inhibitor of the Src family kinases, PP2, down-regulated wild-type alpha(1)beta but not alpha(1)beta(Y413F) receptors. Together, these findings indicate that GlyR function is upregulated by PTKs and this modulation is dependent on the tyrosine-413 residue of the beta subunit.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Down-Regulation / drug effects
  • Electrophysiology
  • Enzyme Inhibitors / pharmacology
  • Hippocampus / cytology
  • Hippocampus / enzymology
  • Hippocampus / metabolism*
  • Humans
  • In Vitro Techniques
  • Kinetics
  • Male
  • Neurons / enzymology
  • Neurons / metabolism*
  • Patch-Clamp Techniques
  • Phosphorylation
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Protein-Tyrosine Kinases / metabolism*
  • Rats
  • Receptors, Glycine / biosynthesis
  • Receptors, Glycine / genetics
  • Receptors, Glycine / metabolism*
  • Receptors, Glycine / physiology*
  • Recombinant Proteins / metabolism
  • Spinal Cord / physiology
  • Synaptic Transmission / physiology
  • Tyrosine / physiology
  • Up-Regulation / drug effects

Substances

  • Enzyme Inhibitors
  • Receptors, Glycine
  • Recombinant Proteins
  • Tyrosine
  • Protein-Tyrosine Kinases