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Involvement of pertussis toxin‐sensitive GTP‐binding proteins in sphingosine 1‐phosphate‐induced activation of phospholipase CCa 2+ system in HL60 leukemia cells
Author(s) -
Okajima Fumikazu,
Tomura Hideaki,
Sho Kimie,
Nochi Hiromi,
Tamoto Koichi,
Kondo Yoichi
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01526-4
Subject(s) - pertussis toxin , sphingosine 1 phosphate , sphingosine , hl60 , phospholipase c , leukemia , g protein , gtp' , chemistry , toxin , phospholipase , microbiology and biotechnology , biology , biochemistry , immunology , enzyme , receptor
Exogenous sphingosine 1‐phosphate (S1P) induced Ca 2+ mobilization, in association with an increase in inositol polyphosphate production reflecting activation of phospholipase C in HL60 leukemia cells. The increase in intracellular Ca 2+ concentration ([Ca 2+ ] i ) induced by S1P was inhibited by an appropriate treatment of the cells with pertussis toxin (PTX), U73122 (a phospholipase C inhibitor) or phorbol 12‐myristate 13‐acetate (PMA). In parallel with the Ca 2+ response, these agents also inhibited inositol polyphosphate production. The S1P‐induced Ca 2+ response was also attenuated in the dibutyryl cAMP‐induced differentiated cells, where GTP‐binding protein‐induced Ca 2+ response is suggested to be enhanced. Lysophosphatidic acid (LPA) also increased [Ca 2+ ] i in the cells, but the maximal response was about half of that of S1P, and furthermore PTX and dibutyryl cAMP treatment hardly affected the LPA‐induced Ca 2+ mobilization. We conclude that exogenous S1P mobilizes Ca 2+ through phospholipase C activation. The S1P‐induced enzyme activation is at least partly mediated by PTX‐sensitive GTP‐binding protein‐coupled receptors which may be different from LPA receptors.