The effect of 3-methylindole on the rates of phospholipid and neutral lipid synthesis in cultured fibroblasts.
The present study was designed to test the hypothesis that a pneumotoxin, 3-methylindole, alters the basic metabolic pathways involved in phospholipid and neutral lipid synthesis in cultured fibroblasts. Rat skin fibroblasts were obtained from day-old pups. Confluent monolayers were preincubated for up to 24 h with a range of concentrations (0-0.76 mM) of 3-methylindole. Following these treatments, the cell lipids were labelled by incubation for 6 h with [14C]glycerol. The lipids were extracted, separated by thin layer chromatography, and the radioactivity in each fraction was determined. 3-Methylindole had no effect on the total incorporation of [14C]glycerol into lipids, but significantly altered the distribution among lipid fractions. Incubation with 3-methylindole caused a decrease in the incorporation of [14C]glycerol into phosphatidylcholine, while radioactivity accumulated in the neutral lipid fraction. The other lipid fractions responded variably. Similarily, Flow 2000 human diploid lung fibroblasts were incubated for 24 h with 3-methylindole followed by treatment with [14C]glycerol, resulting in a 74% decrease in the incorporation of [14C]glycerol into phosphatidylcholine and a 50% increase in its accumulation in neutral lipid. The results indicate that 3-methylindole inhibits the synthesis of phosphatidylcholine from diacylglycerol precursors on the endoplasmic reticulum in cultured fibroblasts. This is an important observation as it shows that 3-methylindole affects the synthesis of phospholipids required for membrane turnover in cells that are not specialized for the production of phospholipids for surfactant.
Department of Nutritional Sciences, College of Biological Science, University of Guelph, Ont., Canada.
J B
JB
Kirkland
T M
TM
Bray
W J
WJ
Bettger
D000818:Animals; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D007700:Kinetics; D008055:Lipids / Q000096:biosynthesis*; D008168:Lung / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis*; D051381:Rats; D012862:Skatole / Q000494:pharmacology*; D012867:Skin / Q000378:metabolism
D007211:Indoles; D008055:Lipids; D010743:Phospholipids; D012862:Skatole; D005990:Glycerol