Modulation of NMDA‐mediated excitotoxicity by protein kinase C

• Published in: Journal of neurochemistry Vol. 78; no. 4; pp. 715 - 726
• Main Authors: Wagey, R., Hu, J., Pelech, S. L., Raymond, L. A., Krieger, C.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-08-2001; Blackwell
• Subjects: amyotrophic lateral sclerosis; Amyotrophic Lateral Sclerosis - metabolism; Animals; Biological and medical sciences; Cell Death - drug effects; Cell Fractionation; Cell Line; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Down-Regulation; Enzyme Activation; Enzyme Inhibitors - pharmacology; Excitatory Amino Acid Agonists - toxicity; Fundamental and applied biological sciences. Psychology; glutamate; HEK cells; Humans; Immunoblotting; Indoles - pharmacology; Isoenzymes - metabolism; Mitogen-Activated Protein Kinases - metabolism; N-Methylaspartate - toxicity; neuron death; phorbol ester; Phosphorylation; Protein Isoforms - metabolism; Protein Kinase C - antagonists & inhibitors; Protein Kinase C - metabolism; protein kinases; Protein Structure, Tertiary; Protein Subunits; Pyrroles - pharmacology; Rats; Receptors, N-Methyl-D-Aspartate - genetics; Receptors, N-Methyl-D-Aspartate - metabolism; Tetradecanoylphorbol Acetate - pharmacology; Transfection; Vertebrates: nervous system and sense organs; Nervous system diseases; Protein kinase C; Enzyme; Toxicity; Transferases; Amyotrophic lateral sclerosis; Glutamate receptor; In vitro; Genetic disease; Cell line; Excitotoxicity; Modulation; Central nervous system disease; Degenerative disease; NMDA receptor; Spinal cord disease; Apoptosis
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.2001.00459.x

Excessive activation of N‐methyl‐d‐aspartate (NMDA) receptors leads to cell death in human embryonic kidney‐293 (HEK) cells which have been transfected with recombinant NMDA receptors. To evaluate the role of protein kinase C (PKC) activation in NMDA‐mediated toxicity, we have analyzed the survival of transfected HEK cells using trypan blue exclusion. We found that NMDA‐mediated death of HEK cells transfected with NR1/NR2A subunits was increased by exposure to phorbol esters and reduced by inhibitors of PKC activation, or PKC down‐regulation. The region of NR2A that provides the PKC‐induced enhancement of cell death was localized to a discrete segment of the C‐terminus. Use of isoform‐specific PKC inhibitors showed that Ca2+‐ and lipid‐dependent PKC isoforms (cPKCs), specifically PKCβ1, was responsible for the increase in cell death when phorbol esters were applied prior to NMDA in these cells. PKC activity measured by an in vitro kinase assay was also increased in NR1A/NR2A‐transfected HEK cells following NMDA stimulation. These results suggest that PKC acts on the C‐terminus of NR2A to accentuate cell death in NR1/NR2A‐transfected cells and demonstrate that this effect is mediated by cPKC isoforms. These data indicate that elevation of cellular PKC activity can increase neurotoxicity mediated by NMDA receptor activation.