We examined the mechanism of action of lysophosphatidylcholine (LPC), which is suggested to be involved in the pathogenesis of atherosclerosis and inflammatory disorders, in HL-60 leukaemia cells. Extracellular 1-palmitoyl LPC increased the intracellular Ca2+ concentration in association with production of inositol phosphate. These actions of LPC were markedly inhibited by treatment of the cells with pertussis toxin and U73122, a phospholipase C inhibitor. The lipid-induced stimulation of the phospholipase C/Ca2+ system was also attenuated in the dibutyryl cAMP-induced differentiated (neutrophil-like) cells, in which phospholipase C activation induced by NaF or formyl-Met-Leu-Phe was enhanced. In contrast with the stimulatory action of 1-palmitoyl LPC, 1-stearoyl LPC was inhibitory for the phospholipase C/Ca2+ system stimulated by NaF as well as by 1-palmitoyl LPC or other Ca2+-mobilizing agonists. In a cell-free system, only an inhibitory effect on phospholipase C activity was observed even by 1-palmitoyl LPC; 1-stearoyl LPC was more inhibitive than 1-palmitoyl LPC. Taken together, these results suggest that atherogenic and inflammatory LPC exerts both stimulatory and inhibitory actions on the phospholipase C/Ca2+ system depending on the species of fatty acid residue of the lipid; the stimulatory effect is possibly mediated through G-protein-coupled receptors; the inhibitory effect might be caused by dysfunction of the components involved in the enzyme system owing to the amphiphilic nature of the lipid. 1-Palmitoyl LPC prefers the former receptor stimulation at least in intact cells, but 1-stearoyl LPC preferentially exerts the latter inhibitory action.
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Research Article|
December 01 1998
Stimulatory and inhibitory actions of lysophosphatidylcholine, depending on its fatty acid residue, on the phospholipase C/Ca2+ system in HL-60 leukaemia cells
Fumikazu OKAJIMA;
Fumikazu OKAJIMA
1
*Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan
1To whom correspondence should be addressed (e-mail fokajima@news.sb.gunma-u.ac.jp).
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Koichi SATO;
Koichi SATO
*Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan
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Hideaki TOMURA;
Hideaki TOMURA
*Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan
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Atsushi KUWABARA;
Atsushi KUWABARA
*Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan
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Hiromi NOCHI;
Hiromi NOCHI
†Department of Microbiology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-02, Japan
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Koichi TAMOTO;
Koichi TAMOTO
†Department of Microbiology, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-02, Japan
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Yoichi KONDO;
Yoichi KONDO
*Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi 371-8512, Japan
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Yukiko TOKUMITSU;
Yukiko TOKUMITSU
‡Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 011, Japan
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Michio UI
Michio UI
§The Tokyo Metropolitan Institute of Medical Science, Honkomagome 3-18-22, Tokyo, Japan
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Publisher: Portland Press Ltd
Received:
July 20 1998
Revision Received:
September 07 1998
Accepted:
September 30 1998
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1998
1998
Biochem J (1998) 336 (2): 491–500.
Article history
Received:
July 20 1998
Revision Received:
September 07 1998
Accepted:
September 30 1998
Citation
Fumikazu OKAJIMA, Koichi SATO, Hideaki TOMURA, Atsushi KUWABARA, Hiromi NOCHI, Koichi TAMOTO, Yoichi KONDO, Yukiko TOKUMITSU, Michio UI; Stimulatory and inhibitory actions of lysophosphatidylcholine, depending on its fatty acid residue, on the phospholipase C/Ca2+ system in HL-60 leukaemia cells. Biochem J 1 December 1998; 336 (2): 491–500. doi: https://doi.org/10.1042/bj3360491
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