Activation of p42erk2MAPK and p90rskby IL-2 Occurs Independently of Protein Kinase C

Abstract

Stimulation of the human interleukin-2 (IL-2)-dependent cell line, Kit225, with IL-2 resulted in the rapid activation of microtubule-associated protein-2 kinase (MAPK), as demonstrated by the tyrosine phosphorylation of p42erk2, the reduced mobility of MAPK in SDS–PAGE gels, and the increased ability of lysates from these cells to phosphorylate myelin basic protein. Measurements of kinase activity in immunoprecipitates of p90 ribosomal S6 kinase (p90rsk) demonstrated that stimulation of this cell line with IL-2 also resulted in the activation of p90rsk. Further, increased MAPK activity occurred following IL-2 stimulation, but not following phorbol 12-myristate 13-acetate (PMA) stimulation in cells depleted of PKC by prolonged treatment with a high concentration of PMA. These results demonstrate that IL-2 stimulation results in the activation of MAPK and p90rskand that this activation occurs in a PKC-independent manner.