VLDL-bound lipoprotein lipase facilitates the cholesteryl ester transfer protein-mediated transfer of cholesteryl esters from HDL to VLDL

In recent years, it has been established that lipoprotein lipase (LPL) is p artly associated with circulating lipoproteins. This report describes the e ffects of physiological amounts of very low density lipoprotein (VLDL)-boun d LPL on the cholesteryl ester transfer protein (CETP)-mediated cholesteryl ester transfer (CET) from high density lipoprotein (HDL) to VLDL, Three pa tients with severe LPL deficiency exhibited a strong decrease in net mass C ET that was more than 80% lower than that of common hypertriglyceridemic su bjects. Recombination experiments showed that this was due to an abnormal b ehavior of the VLDL fraction. Replacement of the latter by normal VLDL tota lly normalized net mass GET. We therefore prepared VLDL containing controll ed amounts of bound LPL that we used as CE accepters in experiments involve d unidirectional radioisotopic CET measurements. These were carried out eit her in the absence or in the presence of inhibitors of LPL lipolytic activi ty. When LPL-induced lipolysis was totally blocked, the stimulating effect of the enzyme on the CETP-dependent CET was only reduced by about 50%, show ing that it did not entirely result from its lipolytic action, These data w ere dependent upon neither the type of LPL inhibitor (E600 or THL) nor the source of CETP (delipidated plasma or partially purified CETP). Thus, in ad dition to the well-known stimulating effect of LPL-dependent lipolysis on G ET, our work demonstrates that physiological amounts of VLDL bound LPL may facilitate CET through a mechanism partially independent of its lipolytic a ctivity.-Pruneta, V., T. Pulcini, F. Lalanne, C. Marcais, F. Berthezene, G. Ponsin, and P. Moulin. VLDL-bound lipoprotein Lipase facilitates the chole steryl ester transfer protein-mediated transfer of cholesteryl esters from HDL to VLDL.