Regulation of the excitatory amino acid transporter EAAT5 by the serum and glucocorticoid dependent kinases SGK1 and SGK3

Biochem Biophys Res Commun. 2005 Apr 8;329(2):738-42. doi: 10.1016/j.bbrc.2005.02.035.

Abstract

In the mammalian retina, glutamate re-uptake is mediated by the sodium dependent cotransport systems EAAT1-5 thus terminating neuronal excitation and preventing neuroexcitotoxicity. In retinal amacrine and ganglion cells, EAAT5 is colocalized with the serum and glucocorticoid inducible kinase SGK1, a serine/threonine kinase known to regulate transport. The study explored the possible regulation of EAAT5 by SGK1, its isoform SGK3, and the closely related protein kinase B. EAAT5 was coexpressed in Xenopus laevis oocytes with or without the respective kinases. Transport activity was quantified by electrophysiology and cell surface expression was determined by chemiluminescence. Both EAAT5 mediated currents and EAAT5 protein abundance at the cell surface were increased by a factor of 1.5-2 upon coexpression of SGK1 or SGK3 but not following coexpression of PKB. In conclusion, the kinases SGK1 and SGK3 increase EAAT5 activity by increasing cell surface abundance of the carrier.

MeSH terms

  • Amino Acid Substitution
  • Amino Acid Transport Systems / genetics
  • Amino Acid Transport Systems / metabolism*
  • Animals
  • Cells, Cultured
  • Excitatory Amino Acid Transporter 5
  • Gene Expression Regulation / physiology
  • Humans
  • Immediate-Early Proteins
  • Membrane Potentials / physiology*
  • Mutagenesis, Site-Directed
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Oocytes / physiology*
  • Photoreceptor Cells / metabolism*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • Recombinant Proteins / metabolism
  • Signal Transduction / physiology*
  • Structure-Activity Relationship
  • Xenopus laevis

Substances

  • Amino Acid Transport Systems
  • Excitatory Amino Acid Transporter 5
  • Immediate-Early Proteins
  • Nuclear Proteins
  • Recombinant Proteins
  • SLC1A7 protein, human
  • Protein Serine-Threonine Kinases
  • serum-glucocorticoid regulated kinase