Lysophosphatidylcholine-induced taurine release in HeLa cells involves protein kinase activity

It has recently been demonstrated that exogenous addition of low concentrat ions (< 15 muM) of lysophosphatidyl choline (LPC, palmitic acid in the sn-1 position) induces a transient increase in taurine efflux from HeLa cells i n a process that seems to involve generation of reactive oxygen species (RO S) and tyrosine phosphorylation U. Membrane Biol. 176 (2000) 175-185). We n ow demonstrate that LPC also induces release of taurine under isotonic cond itions in mouse fibroblast (NIH/3T3) and Ehrlich ascites tumor cells. Furth ermore, we show that in the case of HeLa cells addition of the calmodulin a ntagonist W-7 (50 muM) or the calmodulin-dependent kinase II (CaMKII) inhib itor KN-62 (10 muM) reduces the LPC-induced taurine release under isotonic conditions. Conversely, addition of a standard protein kinase C (PKC) inhib itor chelerythrine (10 muM) leads to a potentiation of the LPC-induced taur ine efflux, whereas direct activation of PKC by the phorbol ester PMA has n o effect. It is suggested that the putative generation of ROS following add ition of LPC is modulated by calmodulin/CaMKII, and that the effect of chel erythrine is more likely related to the ROS production than to PKC inhibiti on. (C) 2001 Elsevier Science Inc. All rights reserved.