Inactivation of JNK activity by mitogen-activated protein kinase phosphatase-2 in EAhy926 endothelial cells is dependent upon agonist-specific JNK translocation to the nucleus

We have investigated the termination of agonist-stimulated mitogen-activated protein (MAP) kinase activity in EAhy926 cells by MAP kinase phosphatase-2 (MKP-2). Zn cells expressing either wild-type (WT) or catalytically inactive (CI)MKP-2, there was no significant differences in TNF alpha -stimulated JNK or p38 MAP kinase activity, however hydrogen peroxide (H2O2)-stimulated JNK activity was substantially reduced in WT-MKP-2 expressing clones and enhanced in cells expressing CI-MKP-2. Consistent with these findings, we observed substantial nuclear translocation of JNK occurred in response to H2O2 but not TNF alpha. Using a phosphospecific anti-JNK antibody, we found that TNF alpha -stimulated JNK activity was associated principally with the cytosol while in response to H2O2, JNK activity was found within the nucleus. These results show that the role of MKP-2 in terminating JNK activity is determined by the translocation of JNK to the nucleus, which is under agonist-specific regulation and not a universal cellular response to stimulation. (C) 2001 Elsevier Science Inc. All rights reserved.