Prostacyclin-induced rundown of N-methyl-D-aspartate receptor currents in HEK293 cells is protein kinase A-dependent and NR2 subunit-selective.
Previous studies in neurons have demonstrated a rapid decrease in NMDA receptor currents following tyrosine kinase inhibition or exposure to platelet-derived growth factor (PDGF). Inhibitors of protein kinase A (PKA) block the PDGF-induced rundown suggesting a multistep pathway that leads to decreased amplitudes of NMDA-activated currents. In this study, HEK293 cells expressing different NMDA receptor subunits were used to study the effects of prostacyclin receptor-mediated PKA activation on the magnitude of glutamate-activated currents. The prostacyclin agonist iloprost induced a rapid and time-dependent depression of otherwise stable glutamate-activated currents in cells expressing NR1-2a/2A or NR1-2a/2D receptors but not NR1-2a/2B or NR1-2a/2C receptors. This rundown was prevented by treatment of cells with the PKA inhibitor H89. The iloprost effect persisted in cells coexpressing NR1-2a/2A receptors and either wild-type or mutant Src kinase (SrcS17A). Co-expression of PSD-95 with NR1-2a/2A receptors reduced but did not eliminate the extent of rundown. Iloprost also produced current rundown in cells expressing NR1-2a and a C-terminal truncated NR2A subunit (NR2A1050stop) but not in those transfected with an NR2A tyrosine mutant (Y842F). The iloprost-induced rundown of wild-type NR1-2a/2A receptors was prevented by prior exposure of cells to hypertonic sucrose. These results suggest that PKA influences the functional activity of NMDA receptors in an NR2 subunit-selective fashion.
Woodward
John J
JJ
Department of Physiology and Neuroscience, MUSC, Charleston, USA. woodward@musc.edu
D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011464:Epoprostenol / Q000819:agonists; D018698:Glutamic Acid / Q000494:pharmacology; D006801:Humans; D016285:Iloprost / Q000494:pharmacology*; D007668:Kidney / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D021122:Protein Subunits; D044006:Receptors, Epoprostenol; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism*; D011982:Receptors, Prostaglandin / Q000819:agonists / Q000378:metabolism; D014162:Transfection; D014665:Vasodilator Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D021122:Protein Subunits; D044006:Receptors, Epoprostenol; D016194:Receptors, N-Methyl-D-Aspartate; D011982:Receptors, Prostaglandin; D014665:Vasodilator Agents; D018698:Glutamic Acid; D011464:Epoprostenol; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D016285:Iloprost; D002118:Calcium