ISSN:
0730-2312
Keywords:
cell growth
;
egg lecithin
;
ether-linked phospholipids
;
phosphatidylcholine
;
phosphatidylinositol
;
PI-3-kinase
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Phosphatidylcholine (PC) from marine invertebrates is enriched in ether-linked forms. PCs from ray fish, Dasyatis sp., and bivalve, Macoma birmanica, used in the present study, contain 65% and 75% (w/w of total PC) of ether-linked forms, respectively. Ether-linked PCs also occur in mammalian membranes. Agonist-mediated hydrolysis of PC generates second messengers which participate in cellular responses. In this study, we tested whether PCs from marine invertebrates directly affect mammalian cell growth and activity of phosphatidylinositol (PI-3-kinase). PI-3-kinase participates in mitogenesis initiated by a variety of growth factors. PI-3-kinase converts polyphosphoinositides to 3′ phosphorylated isomers and these products accumulate in response to mitogenic stimuli. Whether cell membrane lipids regulate PI-3-kinase activity is not known. The marine animal-derived PCs and dioleoyl DAG (dioleoylglycerol) stimulated growth of murine pre-B lymphocytes, whereas chicken PC (egg lecithin) inhibited growth of these cells. Egg lecithin is also a potent inhibitor of PI-3-kinase activity in vitro. We studied the effect of PCs and DAG on PI-3-kinase activity. Unlike egg lecithin, marine animal PCs enhanced PI-3-kinase activity. We investigated the effect of lipids on PI-3-kinase substrate utilization. PCs enriched in ether-linked species increased utilization of substrates by PI-3-kinase. PCs purified from marine organisms also contain a substantially higher percentage of the cis-unsaturated fatty acids, especially of the - ω3 series (25% and 30% of total fatty acids for Dasyatis sp. and Macoma birmanica, respectively), as compared to vertebrate sources. In spite of differences in fatty acid composition, marine PCs and dioleoyl DAG showed similar effects on cell growth and PI-3-kinase activity. These findings indicate that ether-linked phospholipids activate PI-3-kinase and may participate in mitogenic responses. © 1994 Wiley-Liss, Inc.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcb.240550116
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