Phosphatidylinositol-3-kinase activation and atypical protein kinase C ζ phosphorylation characterize the DMSO signalling in erythroleukemia cells

Here we provide evidence for a role of phosphatidylinositol-3-kinase (PI-3-kinase) and for its product phosphatidylinositol-3,4,5-triphosphate (PI3,4,5P3) in the occurrence of the metabolic differentiation state induced by DMSO in murine Friend erythroleukemia cells. Of note, the activation of PI-3-kinase correlated with the modulation of the activation of another enzyme, the atypical protein kinase C zeta (aPKC zeta). In particular, the expression of PI-3-kinase was substantially unaffected by DMSO treatment while its phosphorylation and the production of PI3,4,5P3 was strongly increased within 24 h of DMSO. Such a result was paralleled by an evident phosphorylation of a PKC zeta. Treatment of the cells with the two unrelated PI-3-kinase inhibitors wortmannin and LY 294002 impaired the recovery of the number of differentiated cells, therefore indicating that PI-3-kinase might be involved in the induction of erythroid differentiation, possibly engaging a protein kinase C zeta as downstream effector. (C) 2000 Elsevier Science Inc. All rights reserved.