The role of phosphatidylethanolamine methylation in the secretion of very low density lipoproteins by cultured rat hepatocytes: rapid inhibition of phosphatidylethanolamine methylation by bezafibrate increases the density of apolipoprotein B48-containing lipoproteins
Abstract
The role of phosphatidylcholine (PC) synthesis via the phosphatidylethanolamine (PE) methylation pathway in the secretion of very low density lipoproteins (VLDL) by cultured rat hepatocytes has been investigated by determining the effects of inhibitors. We have shown that bezafibrate and clofibric acid, known hypolipidemic agents, are potent inhibitors of PE methylation (see accompanying paper by Nishimaki-Mogami et al. (1996) Biochim. Biophys. Acta 1304). In hepatocytes incubated with ethanolamine, which maintained cellular PE levels and PE methylation activity, bezafibrate (200 microM) decreased the secretion of triacylglycerol (TG), PC, apolipoproteins B48, and E in VLDL by 50-75%. In contrast, bezafibrate at this concentration had marginal effect on VLDL secretion (83-115% of control) by hepatocytes that had been cultured in the absence of ethanolamine. In these cells PE levels and PE methylation activity had decreased by approx. 40%. VLDL secretion was decreased at concentrations similar to those required to inhibit PE methylation, and was accompanied by an increase in cellular TG levels. The same ethanolamine-dependent effects were produced by clofibric acid and also by 3-deazaadenosine (DZA), an inhibitor of cellular met...Continue Reading
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Hepatotoxicity and mechanism of action of haloalkanes: carbon tetrachloride as a toxicological model
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