EXPRESSION OF MESSENGER-RNA FOR THE PROTOONCOGENE C-FOS IN RAT BASOPHILIC LEUKEMIA-CELLS

Recently, the expression of the mRNA for the proto-oncogene c-fos foll owing activation of the high-affinity receptor for immunoglobulin E in rodent mast cells has been reported. In the present study we investig ated different biochemical events that may play a role in signal trans duction pathways culminating in the expression of c-fos mRNA in rat ba sophilic leukaemia cells. Similar to IgE-mediated cell degranulation w e demonstrated inhibition of the c-fos signal in the absence of calciu m and after preincubation of cells with the protein tyrosine kinase in hibitor genistein. Activation of RBL-2H3 cells by short term PMA treat ment failed to induce cell degranulation or expression of mRNA for c-f os. Depletion of protein kinase C by PMA pre-treatment resulted in sub stantial inhibition of the c-fos signal. In contrast to IgE-mediated c ell degranulation, expression of mRNA for c-fos was not dependent on c ontinued receptor aggregation. In addition, we demonstrate that c-fos mRNA expression is not restricted to Fc epsilon RI activation but can be induced by a variety of IgE independent mechanisms including calciu m influx by ionophore A 23187 and stimulation of G proteins. Copyright (C) 1997 Elsevier Science Inc.