ACTIVATION OF P42(ERK2) MAPK AND P90(RSK) BY IL-2 OCCURS INDEPENDENTLY OF PROTEIN-KINASE-C

Stimulation of the human interleukin-2 (IL-2)-dependent cell line, Kit 225, with IL-2 resulted in the rapid activation of microtubule-associa ted protein-2 kinase (MAPK), as demonstrated by the tyrosine phosphory lation of p42(erk2), the reduced mobility of MAPK in SDS PAGE gels, an d the increased ability of lysates from these cells to phosphorylate m yelin basic protein. Measurements of kinase activity in immunoprecipit ates of p90 ribosomal S6 kinase (p90(rsk)) demonstrated that stimulati on of this cell line with IL-2 also resulted in the activation of p90( rsk). Further, increased MAPK activity occurred following IL-2 stimula tion, but not following phorbol la-myristate 13-acetate (PMA) stimulat ion in cells depleted of PKC by prolonged treatment with a high concen tration of PIMA. These results demonstrate that IL-2 stimulation resul ts in the activation of MAPK: and p90(rsk) and that this activation oc curs in a PKC-independent manner. (C) 1996 Academic Press, Inc.