Kainate receptor-mediated apoptosis in primary cultures of cerebellar granule cells is attenuated by mitogen-activated protein and cyclin-dependent kinase inhibitors

Abstract

1. Previous studies have suggested that neuronal apoptosis is the result of an abortive attempt to reenter the cell cycle, and more recently the cyclin-dependent (CDKs) and the mitogen-activated protein (MAP) kinases, two superfamilies of kinases that influence and control cell cycle progression, have been implicated in neuronal apoptosis. 2. Here, to examine whether CDK/ MAPK related pathways are involved in excitotoxicity, we studied the actions of various kinase inhibitors on apoptosis induced by the ionotropic glutamate (Glu) receptor agonist, kainate (KA), in primary cultures of murine cerebellar granule cells (CGCs). 3. KA-mediated neurotoxicity was concentration-dependent, as determined by a cell viability assay monitoring the reduction of 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and largely apoptotic in nature, as shown by morphological examination and labeling of DNA fragmentation in situ using terminal deoxynucleotidyl transferase (TDT)-mediated dUTP digoxigenin nick-end labelling (TUNEL). 4. KA-mediated neurotoxicity and apoptosis was completely attenuated by the mixed CDK and MAP kinase inhibitor, olomoucine, in a concentration-dependent manner (50-600 μM), and partially by roscovitine (1-100 μM), a more selective CDK inhibitor. 5. The p38 MAP kinase inhibitor, SB203580 (1-100 μM), partially attenuated KA receptor-mediated apoptosis, as did the MAP kinase kinase inhibitors PD98509 (1-100 μM) and U0126 (1-100 μM). 6. These findings provide new evidence for a complex network of interacting pathways involving CDK/MAPK that control apoptosis downstream of KA receptor activation in excitotoxic neuronal cell death.