We investigated which isoforms of PKCs can be modulated and what their roles are during L-buthionine-S,R-sulfoximine (BSO)-induced neuronal death. We observed the isoform specific translocation of PKC-epsilon from the soluble fraction to the particulate in cortical neurons treated with 10 mM BSO. The translocation of PKC-epsilon by BSO was blocked by antioxidant trolox, suggesting the PKC-epsilon as a downstream of reactive oxygen species (ROS) elevated by BSO. Trolox inhibited the ROS elevation and the neuronal death in BSO-treated cortical cells. The BSO-induced neuronal death was remarkably inhibited by both the pharmacological inhibition of PKC-epsilon with epsilonV1-2 and the functional blockade for PKC-epsilon through overexpression of PKC-epsilon V1 region, suggesting the detrimental role of PKC-epsilon. These results suggest that PKC-epsilon is the major PKC isoform, involved in the pathways triggered by ROS, leading to neuronal death in BSO-treated cortical neurons. (C) 2004 Elsevier Inc. All rights reserved.