Stimulation of EAAC1 in C6 glioma cells by store-operated calcium influx

Biochim Biophys Acta. 2009 Feb;1788(2):551-8. doi: 10.1016/j.bbamem.2008.12.005. Epub 2008 Dec 24.


This study investigated how modulation of intracellular calcium alters the functional activity of the EAAC1 glutamate transporter in C6 glioma cells. Pre-incubation of C6 glioma cells with the endoplasmic reticulum Ca2+ ATP pump inhibitor, thapsigargin (10 microM) produced a time-dependent increase in the Vmax for D-[3H]aspartate transport that reached a maximum at 15 min (143% of control; P<0.001) that was accompanied by increased plasma membrane expression of EAAC1 and was blocked by inhibition of protein kinase C. Pre-incubation of C6 glioma cells with phorbol myristate-3-acetate (100 nM for 20 min) also caused a significant increase in the Vmax of sodium-dependent D-[3H]aspartate transport (190% of control; P<0.01). In contrast, in the absence of extracellular calcium, thapsigargin caused a significant inhibition in D-[3H]aspartate transport that was not mediated by protein kinase C. Blockade of store-operated calcium channels with 2-aminoethoxydiphenyl borate (50 microM) or SKF 96365 (10 microM) caused a net inhibition of D-[3H]aspartate uptake. Co-incubation of C6 glioma cells with both thapsigargin and 2-aminoethoxydiphenyl borate (but not SKF 96365) prevented the increase in D-[3H]aspartate transport that was observed in the presence of thapsigargin alone. Furthermore, 2-aminoethoxydiphenyl borate, but not SKF 96365, reduced the increase in intracellular calcium that occurred following pre-incubation of the cells with thapsigargin. It is concluded that, in C6 glioma cells, stimulation of EAAC1-mediated glutamate transport by thapsigargin is dependent on entry of calcium via the NSCC-1 subtype of store operated calcium channel and is mediated by protein kinase C. In contrast, in the absence of store operated calcium entry, thapsigargin inhibits transport.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aspartic Acid / metabolism
  • Biological Transport
  • Calcium / metabolism*
  • Cell Line, Tumor
  • Excitatory Amino Acid Transporter 3 / metabolism*
  • Extracellular Space / drug effects
  • Extracellular Space / metabolism
  • Glioma / metabolism*
  • Mice
  • Protein Kinase C / metabolism
  • Protein Kinase Inhibitors / pharmacology
  • Tetradecanoylphorbol Acetate / pharmacology
  • Thapsigargin / pharmacology


  • Excitatory Amino Acid Transporter 3
  • Protein Kinase Inhibitors
  • Slc1a1 protein, mouse
  • Aspartic Acid
  • Thapsigargin
  • Protein Kinase C
  • Tetradecanoylphorbol Acetate
  • Calcium