Leukotriene D 4-induced activation of protein kinase C in rat basophilic leukemia cells

Abstract

We studied the subcellular distribution of protein kinase C (PKC) in the particulate and cytosolic fractions of rat basophilic leukemia (RBL-1) cells treated with leukotriene D 4 (LTD 4) and compared these results with those of phorbol myristate acetate (PMA). Consistent with the earlier reports, treatment of RBL-1 cells with PMA resulted in a time- and dose-dependent translocation of PKC from cytosolic to the particulate fractions, sustained for at least 10 min. When RBL-1 cells were treated with LTD 4, a small, transient decrease in PKC activity in cytosolic fraction was observed within 7.5 s after LTD 4 treatment. This was accompanied by a significant increase of PKC in the particulate fraction. However, at 15 and 30 s, both particulate and cytosolic PKC activities were increased with LTD 4 treatment. The activation induced by LTD 4 was dose- and time-dependent with maximal effects occuring within 30 s, declining at the later time points. Pretreatment of the cells with 2(R)-hydroxy-3(S)-carboxyethylthio-3-[2-(8- phenyloctyl, phenyl]propanoic acid (SK & F 104353), a high affinity specific LTD 4 receptor antagonist, and also with staurosporine, a potent inhibitor of PKC, completely inhibited the LTD 4-induced activation of PKC both in the particulate and cytosolic fractions. These results suggest that activation of PKC by LTD 4 is different from that elicited by PMA. The ability of SK&F 104353 to block LTD 4-induced activation of PKC further suggests that stimulation of PKC might be an important intermediate step in the signal transduction mechanism of the LTD 4 receptor in RBL-1 cells.