Stimulatory Action of Polyunsaturated Fatty Acids on Pyruvate Oxidation

Repercussion on HMG-CoA Reductase Activity and Cholesterol Turnover in Cultured Infant Liver Cells
  • D. Lapous
  • C. Loriette
  • J. Raulin
  • C. Wolfrom
  • M. Gautier
Part of the GWUMC Department of Biochemistry Annual Spring Symposia book series (GWUN)


In a previous report, we have shown that short-term exposure of cultured infant skin fibroblasts (ISF) to various radioactive long-chain fatty acids gave different rates of labeled acetyl-CoA incorporation into cholesterol. The present work was extended to infant liver cells (ILC). We also examined whether nonradioactive unsaturated and polyunsaturated fatty acids (PUFAs) could individually influence the level of acetyl-CoA and/or HMG-CoA, substrates for cholesterogenesis: any modification in the flow of acetyl-CoA, a product of both ß-oxidation and pyruvate dehydrogenase (PDH) activity. would affect HMG-CoA level, HMG-CoA reductase (HMGR) activity, and then cholesterol synthesis.

The lipoprotein-deprived medium currently used to stimulate HMGR activity in cultured cells 24-36 hr before determination also provoked a moderate PUFA deficiency, which was progressively cancelled by addition of linoleic (LI) or arachidonic (AR) acid to the medium. During the 6-hr period of rehabilitation, the level of acetyl-CoA from LI and AR ß-oxidation was rather low and without effect on PDH deactivation compared to cells incubated with oleic acid (OL). In fact, adding 0.25 mM PUFA to the lipoprotein-poor medium proved more effective in increasing PDH activity than incubation of control cells with 5 mM dichloroacetate, an inhibitor of PDH kinase.

Addition of LI, and especially of AR, had a stimulatory effect on PDH and HMGR activity. The PDH activity was more responsive to the increase in PUFA concentration in ISF (up to 47% stimulation) than in ILC (10%). The HMGR activity was very sensitive to LI and AR concentration, and the increase in activity reached 39% and 70%, respectively. In contrast, the addition of 0.25 mM OL had inhibitory effect on PDH and HMGR activity (7–19% and 30–35% lower than controls, respectively). These differences in PDH and HMGR activity between the groups had repercussion on cholesterol specific radioactivity, determined after cell incubation with labeled fatty acids. When cells were kept in the medium supplemented with fetal bovine serum and not transferred to lipoprotein-deprived medium, addition of OL again provoked reduction of PDH activity (20% lower than controls), whereas adding LI or AR had only a slight (if any) inhibitory effect (7–13%).

Therefore, the slight inhibitory effect of the added PUFAs on pyruvate (and then on glucose) oxidation—contrasting with the significant inhibitory effect of OL, considered a risk factor of cardiovascular disease—suggests one of the mechanisms of their beneficial function. This interpretation also takes into account the possible impact on cholesterol turnover.


Pyruvate Dehydrogenase Cellular Lipid Cellular Cholesterol Label Fatty Acid Pyruvate Oxidation 


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  1. Brown, M. S., Dana, S. E., and Goldstein, J. L., 1974, Regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in cultured human fibroblasts. Comparison of cells from a normal subject and from a patient with homozygous hypercholesterolemia, J. Biol. Chem. 249:789–796.PubMedGoogle Scholar
  2. Carreau, J. P., Lapous, D., and Raulin, J., 1980, Cholesterol synthesis in the liver, kidneys and brain after injection of uniformly 14C-labeled oleic or linoleic acid to developing rats, Ann. Nutr. Metab. 26:217–226.CrossRefGoogle Scholar
  3. Cenedella, R. J., 1982, Digitonide precipitable sterols: Reevaluation with special attention to lanosterol, Lipids M3-AA.PubMedCrossRefGoogle Scholar
  4. Faust, J. R., Luskey, K. L., Chin, D. J., Goldstein, J. L., and Braun, M. S., 1982, Regulation of synthesis and degradation of 3-hydroxy-3-methylglutaryl-CoA reductase by low-density lipoprotein and 25-hydroxycholesterol in UT-1 cells, Proc. Natl. Acad. Sci. U.S.A. 79:5205–5209.PubMedCrossRefGoogle Scholar
  5. Galli, G., and Paoletti, E. G., 1967, Separation of cholesterol-desmosterol acetates by thin-layer and column chromatography on silica gel-G silver nitrate, Lipids 2:72–75.PubMedCrossRefGoogle Scholar
  6. Gebhard, R. L., Stone, B. G., and Prigge, W. F., 1985, Three hydroxy-3-methylglutaryl-coenzyme A reductase activity in the human gastrointestinal tract, J. Lipid Res. 26:47–53.PubMedGoogle Scholar
  7. Gibbons, G. F., 1985, The relationship between cholesterol synthesis and other metabolic processes, in: Journées du G.E.R.L.I., Le Cholesterol ,(C. Lutton, ed.), Orsay, France, pp. 6–7.Google Scholar
  8. Gibbons, G. F., and Pullinger, C. R., 1977, Measurement of the absolute rates of cholesterol biosynthesis in isolated rat liver cells, Biochem. J. 161:321–330.Google Scholar
  9. Gibbons, G. F., and Pullinger, C. R., 1979, Utilization of endogenous and exogenous sources of substrate for cholesterol biosynthesis by isolated hepatocytes, Biochem. J. 177:255–263.PubMedGoogle Scholar
  10. Gibbons, G. F., Björnsson, O. G., and Pullinger, C. R., 1984, Evidence that changes in hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity are required partly to maintain a constant rate of sterol synthesis, J. Biol. Chem. 259:14399–14405.PubMedGoogle Scholar
  11. Gregg, R. G., and Wilce, P. A., 1985, Effect of assay temperature and the kinetics of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in rat liver and Morris hepatoma 5123 C., Int. J. Biochem. 17:707–711.PubMedCrossRefGoogle Scholar
  12. Grundt, I. K., Loriette, C., Lapous, D., and Raulin, J., 1985, Effect of fatty acids from cod-liver oil and sunflower oil on HMG-CoA reductase activity in cultured brain cells, in: Proceedings 13th Scandinavian Symposium on Lipids (R. Marcuse, ed.), Lipidforum, Göteborg, Sweden, pp. 31-36.Google Scholar
  13. Hansen, T. L., 1982, Determination of pyruvate dehydrogenase in cultured human fibroblasts and amniotic fluid cells, Clin. Chem. Acta 123:45–50.CrossRefGoogle Scholar
  14. Hillmar, I., Henze, K. A., and Barth, C. A., 1983, Influence of fatty acids on cholesterol synthesis of hepatocytes in monolayer culture, J. Nutr. 113:2239–2244.PubMedGoogle Scholar
  15. Lemonnier, F., Gautier, M., Moati, N., and Lemonnier, A., 1976, Comparative study of extracellular amino-acids in culture of human liver and fibroblasts, In Vitro 12:460–466.PubMedCrossRefGoogle Scholar
  16. Loriette, C., Vignikin, R., Lapous, D., Wolfrom, C., Polini, G., Gautier, M., and Raulin, J., 1987, Permissive role of n-6 polyunsaturated fatty acids on carbohydrate oxidation in infant skin fibroblasts. One possible mechanism of their intervention on coronary heart disease and diabetes, J. Am. Coll. Nutr. 6(4):(in press).Google Scholar
  17. Lowry, O. H., Rosebrough, N. J., Farr, A. L., and Randall, R. J., 1951, Protein measurement with the Folin phenol reagent, J. Biol. Chem. 193:265–275.PubMedGoogle Scholar
  18. Pullinger, C. R., and Gibbons, G. F., 1981, Biphasic effect of exogenous oleate and the rate of cholesterol biosynthesis by rat hepatocytes, Biochem. Biophys. Res. Commun. 99:37–43.PubMedCrossRefGoogle Scholar
  19. Pullinger, C. R., and Gibbons, G. F., 1983, The role of substrate in the regulation of cholesterol biosynthesis in rat hepatocytes, Biochem. J. 210:625–632.PubMedGoogle Scholar
  20. Radin, N. S., 1981, Extraction of tissue lipids with a solvent of low toxicity, Methods Enzymol. 72:5– 7PubMedCrossRefGoogle Scholar
  21. Ramatullah, M., and Roche, T. E., 1985, Modification of bovine kidney pyruvate dehydrogenase kinase activity by CoA esters and their mechanism of action, J. Biol. Chem. 260:10146–10152.Google Scholar
  22. Raulin, J., and Grndt, I. K., 1980, Incorporation of l4C from carboxyl-labeled oleoyl-, linoleoyl-and arachidonoyl-CoA into water soluble and insoluble fractions of rat liver slices. Methodology for in vitro experiments, Anal, biochem. 101:204–214.CrossRefGoogle Scholar
  23. Raulin, J., Lapous, D., Bouchéne, M., Loriette, C., Wolfrom, C., Polini, G., and Gautier, M., 1983, Extent of l4C incooration into cholesterol of infant skin fibroblasts incubated with carboxyllabeled oleic, linoleic or arachidonic acids, Biochimie 65:389–396.PubMedGoogle Scholar
  24. Raulin, J., Loriette, C., Lapous, D., Wolfrom, C., Polini, G., and Gautier, M., 1984, Influence of essential fatty acids of pyruvate dehydrogenase activity. Resultant effect upon cholesterol specific radioactivity of infant skin fibroblasts incubated with l4C-labeled fatty acids, in: Fats for the Future (S. C. Brooker, A. Renwick, S. F. Hannan, and L. Eyres, eds.), Duromarck, Auckland, pp. 125-127.Google Scholar
  25. Raulin, J., Loriette, C., Lapous, D., Wolfrom, C., and Gautier, M., 1985, Hypothetical elicitation of the beneficial effect of PUFAs as slight inhibitors of glucose oxidation in cultured liver cells, in: 28th Annual Meeting of American College of Nutrition,.Google Scholar
  26. Raulin, J., Lapous, D., Loriette, C., and Grundt, I. K., 1986, 3-Hydroxy-3-methylglutaryl-CoA reductase activity in cultured rat brain cells. Sensitivity to n-3 and n-6 polyunsaturated fatty acids from cod-liver and sunflower oils, in: Proceedings NATO Workshop: Enzymes in Lipid Metabolism II ,NATO ASI Series, Plenum, NY, pp. 479–484.Google Scholar
  27. Rosenthal, M. D., and Whitehurst, M. C., 1982, Selective utilization of omega-6 and omega-3 polyunsaturated fatty acids by human skin fibroblasts, J. Cell. Physiol. 113:298–306.PubMedCrossRefGoogle Scholar
  28. Schofield, P. J., Griffiths, L. R., Rogers, S. H., and Wise, G., 1980, An improved method for the assay of platelet pyruvate dehydrogenase, Clin. Chem. Acta 108:219–227.CrossRefGoogle Scholar
  29. Vance, D. E., and Pelech, S. L., 1984, Enzyme translocation in the regulation of phosphatidylcholine biosynthesis, Trends Biochem. Sci. 9:17–20.CrossRefGoogle Scholar
  30. Vrána, A., Raulin, J., Loriette, C., and Kazdová, L., 1983, Pyruvate dehydrogenase activity in the liver, adipose-tissue and brain of rats with fructose-induced hypertriglyceridemia, Nutr. Rep. Int. 28:1437–1444.Google Scholar
  31. Young, N., and Berger, B., 1981, Assay of S-3-hydroxy-3-methylglutaryl-CoA reductase, Methods Enzymol. 71:498–509.PubMedCrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • D. Lapous
    • 1
  • C. Loriette
    • 1
  • J. Raulin
    • 1
  • C. Wolfrom
    • 2
  • M. Gautier
    • 2
  1. 1.Laboratoire Biologie CellulaireUniversité Paris 7Paris 05France
  2. 2.INSERM U56, Département Cultures CellulairesHôpital de BicêtreLe Kremlin-BicetreFrance

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