Interaction of normolipidemic very low density lipoproteins with receptors in human skin fibroblasts.

Very low density lipoproteins (VLDL) from normolipidemic subjects were able to bind to the cultured human skin fibroblasts almost as efficiently as low density lipoproteins (LDL). The rate of esterification of cholesterol in the fibroblasts was enhanced by VLDL to the same extent as by LDL. Trypsin treatment of VLDL abolished the binding capacity completely. When trypsin-treated VLDL was partially delipidated with heptane, part of the binding capacity to the fibroblasts was restored. SDS polyacrylamide gel electrophoresis showed that apolipoprotein E (apo E) in VLDL was digested completely by trypsin. Although normal VLDL are recognized by the cells through apolipoprotein E, the major apoprotein of VLDL, that is apolipoprotein B (apo B), is not functional unless the core triglycerides are removed. In contrast to the previous reports which indicate that only hypertriglyceridemic VLDL and not normal VLDL interact with fibroblast receptors, our results clearly show that VLDL from normolipidemic subjects can also bind to these receptors.